Program Report for 1999

Research programsIrrigated rice ecosystem

BREEDING TO BREAK YIELD CEILINGS:A SYSTEMS APPROACH 4Comparison of dry and wet season performance

of new plant type lines (APPA, PBGB) 4Dry season NPT yields 5Wet season NPT yields 5

Hybrid rice (PBGB) 5Release of IRRI hybrids 6Elite hybrids 6New cytoplasmic male sterile lines 7Development of thermosensitive genic

male sterile (TGMS) lines 7IR lines named as varieties 7Hybrid rice network 7

Genetic divergence of maintainer and restorerlines used to breed tropical rice hybrids (PBGB) 7

Association between SSR diversity, pedigree record,quantitative trait variation, and hybrid performance(PBGB) 9

Toward a synthetic apomixis for rice (PBGB) 10Inducing the asexual embryo in

the rice nucellus 11Arresting the sexual embryo development 11

Characterization of root system in a newplant type (APPA) 13

Japonica germplasm utilization for valueadded (PBGB) 14

Inheritance of RTSV resistance in TW5, the near-isogenic line from Utri Merah (EPP, PBGB) 14

Breeding rice for resistance to tungro (PBGB) 15

SUSTAINING SOIL QUALITY IN INTENSIVERICE SYSTEMS 16Yield declines in long-term rice experiments

in Asia (SS, SWS) 16

IMPROVING THE PRODUCTIVITY ANDSUSTAINABILITY OF RICE-WHEATSYSTEMS 18Improving rice-wheat systems (SWS, APPA, EPP,

SS) 18Ecoregional approach to natural resource management

(APPA, SS) 18Soil- and seedborne pathogens of rice in

a rice-wheat system (EPP) 19Field sampling and disease assessment 19Disease incidence in farmers’ fields 19Results from a principal component analysis 20Interpretation of trends 20

IMPROVING PEST MANAGEMENT 20Determinants of farmers’ pest management

decisions (EPP) 20Field evaluation of prototype Tungro Screen B

kits (EPP) 21Alternative prey in irrigated rice: implications

for biological control of hoppers (EPP) 21

PROGRESS OF UNREPORTED PROJECTS 22Increasing water use efficiency in rice culture

(SWS, APPA, SS) 22Coping with global climate change: reducing

methane emission from rice fields (SWS) 23

IRRIGATED RICE RESEARCH CONSORTIUM 23Coordination 23Research 23

PROGRAM OUTLOOK 23

4 IRRI program report for 1999

Irrigated rice ecosystem

Breeding to break yield ceilings:a systems approach

Comparison of dry and wet seasonperformance of new plant type linesS. Peng, G.S. Khush, R. Visperas, and A. Pamplona

We reported in 1998 that the average yield of 43new plant type (NPT) lines was 7.5 t ha–1 as com-pared with 8.1 t ha–1 of check cultivar IR72 in thedry season (DS). However, 51 NPT lines had anaverage yield of 5.2 t ha–1, higher than 5 t ha–1 ofthe check cultivar IR72 in the wet season (WS) (Ta-ble 1). These data suggest that the relative perform-ance of NPT is better in WS than in DS.

Because of limited irrigation, the area planted torice during DS is decreasing in Southeast Asia whilethe WS area is increasing. That makes increasingWS yield by developing new rice cultivars as im-portant for overall rice production as increasingyield potential in DS.

Fifty-two lines were grown in 1999 DS and 58NPT lines were grown in 1999 WS. The checkcultivar was PSBRc 52 in DS and IR72 in WS. ForDS, 22-d-old seedlings were transplanted on 22 Dec1998. WS transplanting was done 1 Jul 1999 with21-d-old seedlings. Hill spacing was 0.10 × 0.15 mwith 1 seedling hill–1. Fertilizer N was 120 kg ha–1.Samples were taken at maturity from a 0.5-m2 areato determine panicle number, spikelets per panicle,grain-filling percentage, and 1000-grain weight.Grain yield was determined from a 5-m2 area andadjusted to moisture content of 0.14 g H2O g–1 freshweight.

Rice production will have to increase as much as 60%in the next 20–30 years to meet growing demand forfood, sustain global food security, and mitigatepoverty. Most of that production will come fromintensive irrigated rice systems.

Competition for land and labor will require in-creased productivity to meet needs for rice. Rates ofyield increase have recently declined in some coun-tries, indicating that further increases in productivitymay be difficult to achieve. A critical issue is mainte-nance of environmental quality while achievingincreases in rice productivity.

The irrigated rice ecosystem research programfocuses on

● breaking current yield barriers,● increasing efficiency of crop production inputs,● closing the yield gap and sustaining the irrigated

lowlands, and● mitigation of the interaction between irrigated

rice and global and atmospheric changes.

Irrigated rice ecosystem 5

Table 1. Minimum, maximum, and average yield (t ha–1) ofnew plant type (NPT) lines and a check cultivar grown inthe dry (DS) and wet season (WS) of 1998-99. The checkcultivar was PSBRc 52 in the dry season of 1999 and wasIR72 in the other seasons. IRRI, 1999.

1998 1999

DS WS DS WS

NPT lines (no.) 43 51 52 58Minimum NPT yield 6.6 3.7 3.7 2.9Maximum NPT yield 8.8 7.7 7.4 6.5Av NPT yield 7.5 5.2 5.6 4.9Yield of check 8.1 5.0 6.7 4.3NPT 3 checka (no.) 7 30 4 49

aNumber of NPT lines with the same or greater yield than the check.

DRY SEASON NPT YIELDS

Four NPT lines produced the same or greater yieldthan PSBRc 52 in 1999 DS. NPT line IR70479-45-2-3 had highest yield at 7.4 t ha–1, about 10% higherthan PSBRc 52. Daily average radiation from Janu-ary to April was 12% lower than the 10-year aver-age and yields were low.

Grain-filling percentage limited the yield ofPSBRc 52, which was below 70%. There was anegative relationship between grain-filling percent-age and spikelets per panicle. Six NPT lines(IR66160-121-4-4-2, IR66160-121-4-5-3,IR65600-42-5-2, IR66160-121-4-1-1, IR68552-84-3-1, and IR65600-54-6-3) had better than 75% grainfilling but their panicle size was small, ranging from110 to 135 spikelets panicle–1. All NPT lines hadbigger panicles than PSBRc 52.

Nine NPT lines had more than 200 spikelets perpanicle, but their grain filling was only 25-50%. SixNPT lines had 150-200 spikelets panicle–1 and 65-75% of grain filling. The next step in the NPTbreeding program is to improve the grain filling ofthose lines.

WET SEASON NPT YIELDS

Forty-nine NPT lines produced the same or greateryield than IR72 in 1999 WS. The average yield ofNPT lines was 4.9 t ha–1 compared with 4.3 t ha–1

for IR72. NPT line IR68552-55-3-2 produced thehighest yield of 6.5 t ha–1, about 50% higher than

IR72. The results confirm that performance of NPTlines is better in WS than in DS.

There are several reasons that may explain thebetter performance of NPT lines in WS.

● NPT lines have better lodging resistance thanthe semidwarf indica type. More lodging oc-curs in WS than in DS.

● Most NPT lines have larger panicles than theindica type. In WS when solar radiation islimiting, panicle-weight type is morefavorable than panicle-number type becauseradiation has a large effect on tillering capac-ity and productive tiller percentage.

● NPT lines usually have a better canopy struc-ture for light interception than the semidwarfindica type, an important characteristic whenlight is a limiting factor.

● Preliminary results suggest that NPT lineshave better shading tolerance than the indicatype in terms of single-leaf photosyntheticrate.

Hybrid riceS.S. Virmani, R. Toledo, C. Casal, R. Ona,D. Sanchez, M. Nas, and M. Ilyas Ahmed

Hybrid rice research at IRRI seeks to exploit thephenomenon of hybrid vigor to increase yield po-tential of rice cultivars beyond that of high-yieldingsemidwarf varieties.

During 1999, 531 elite inbred lines were testedfor their ability to maintain sterility or restore fertil-ity of three cytoplasmic male sterility (CMS) sys-tems (CMS-WA, CMS-ARC, CMS-mutagenizedIR62829B) used in the breeding program. In all,1,554 test crosses were evaluated and 330 newbackcrosses initiated to develop new CMS lines inBC1 to BC6 generations.

We evaluated 454 experimental hybrids in obser-vational yield trials, 245 in preliminary yield trials,and 61 in advanced yield trials. Twenty rice hybridswere nominated for national trials by the PhilippineRice Research Institute (PhilRice) and 37 hybridswere nominated for inclusion in the InternationalRice Hybrid Observation Nursery (IRHON). Nu-cleus and breeder seeds of 81 CMS lines and 31 re-storer lines were also produced for sharing withpublic and private sector institutions working onhybrid rice in national programs.


Table 2. Growth duration and yield of three elite rice hybrids in comparison withcheck variety PSBRc 28 in advanced yield trials. IRRI, 1999.

1999 DS 1999 WS

Hybrid or check variety Growth Yield Growth Yieldduration (t ha–1) duration (t ha–1)

(d) (d)

IR68888A/IR62161-184-3-1-3-2R(IR75207H) 112 7.2 115 4.6IR58025A/IR59606-119-3R (IR69688H) 110 7.0 111 4.6IR68897A/IR59673-93-2-3-3R (IR75582H) 111 6.9 113 4.9PSBRc 28 (check) 115 6.2 116 4.3

LSD (5%) 0.69 .15LSD (1%) 0.91 .20

Table 3. IRRI-bred CMS lines designated in 1999.

CMS line Source Female parent Male parent

IR76765A BCN 0022 G46A/6*IR71564B IR71564BIR76766A BCN 0030 G46A/6*IR69628B IR69628BIR76767A BCN 0042 D297A/6*IR58025B IR58025BIR76768A BCN 0054 D297A/6*IR70959B IR70959BIR76769A BCN 0064 D297A/6*IR69628B IR69628BIR76770A BCN 0072 IR68897A/6*IR68903-4-1-1-3 IR68903-4-1-1-3IR77285A BCN 0862 G46A/8*IR69623B IR69623BIR77286A BCN 0868 GA46A/7*IR69618B IR69618BIR77287A BCN 0874 G46A/*PMS1B PMS1BIR77288A BCN 0880 D297A/7*IR69618B IR69618BIR77289A BCN 0884 D297A/7*IR72079B IR72079BIR77290A BCN 0890 IR68897A/7*IR68907-9-3-1-1 IR68907-9-3-1-1IR77291A BCN 0894 IR68897A/7*IR68908-3-1-2-2 IR68908-3-1-2-2IR77292A BCN 0902 IR68897A/7*IR68908-9-3-2-1 IR68908-9-3-2-1IR77293A BCN 0944 IR68281A/7*Basmati 385-1 Basmati 385-1IR77294A BCN 0924 IR68897A/7*IR68952-8-1-9-4 IR68952-8-1-9-4

RELEASE OF IRRI HYBRIDS

The IRRI hybrid IR69690H (IR58025A/BR 827-35-3-1-1-1R), earlier released in Maharashtra Stateof India, was released for the Red River Delta inVietnam, the first IRRI hybrid released in northernVietnam. IR69690H has better grain quality andadaptability to the summer season than (and yieldcomparable with) Chinese hybrids already commer-cialized in the region. IR69690H has also been reg-istered (along with IR68877H) for on-farm testingin Bangladesh.

ELITE HYBRIDS

Nine hybrids showed significant yield advantage inadvanced yield trials at IRRI during 1999. Three ofthose hybrids yielded consistently high in both sea-sons (Table 2).

NEW CYTOPLASMIC MALE STERILE LINES

Sixteen new CMS lines (Table 3) were designatedpossessing WA (6), Gambiaca (5), and Dissi (5)cytoplasm, indicating a diverse cytoplasmic base ofnew IRRI-bred CMS lines.

A CMS line IR70369A, designated in 1994, wasfound stable for complete pollen sterility, has goodoutcrossing, good phenotypic acceptability, accept-able grain quality (without aroma), and good com-bining ability. During 1999, several heterotic com-binations derived from IR70369A were identified inobservation and preliminary yield trials. Evaluationof maintainer lines for different biotic stresses re-sulted in identification of IR69618B and IR72079Blines possessing multiple resistance to diseases andinsects and showing high phenotypic acceptabilityscore. The corresponding CMS lines had fair to ex-cellent outcrossing scores. These lines will be usedextensively to develop new heterotic combinations.


DEVELOPMENT OF THERMOSENSITIVE

GENIC MALE STERILE (TGMS) LINES

We evaluated 2,149 F3-F6 progenies in the pedigreenursery. Among F5-F6 progenies, 215 good lookingmale sterile plants were selected and transferred tothe phytotron (temperature 27 °C/20 °C) to inducefertility. Fifty-three plants reverted to partial fer-tility. Seeds produced from them were used forevaluation of male sterility in the field at high tem-perature (above 30 °C). Based on their goodphenotypic acceptability score (1–5), good fertilityexpression (score 1–5), and complete male sterilityin the field (using the natural temperature variation),six TGMS lines were identified for sharing withnational programs. Those are IR71007-9-5–1-2-12-2, IR72085-21-19-15-19, IR72093-10-13-26-4,IR72094-12-1-3-30, IR72096-14-10-4-12, andIR72097-10-1-11-25.

IR LINES NAMED AS VARIETIES

Nine IRRI lines from the irrigated breeding prog-ram were named as varieties in six countries (Table4). This brought the number of IRRI breeding linesnamed as varieties by national programs to 317.

HYBRID RICE NETWORK

Several consultancies were completed by the IRRI/Asian Development Bank (ADB) project on Devel-opment and Use of Hybrid Rice in Asia. A con-sultancy organized by IRRI in Bangladesh prepareda national plan for hybrid rice research and devel-opment for the next 5 years. IRRI also had

consultancies in India, Indonesia, and Sri Lanka toreview ongoing research and development activitiesfor hybrid rice.

Training on hybrid rice breeding was presentedat IRRI during Mar-Apr 1999 and special on-the-job training was organized for research personnelfrom Bangladesh, Indonesia, and Vietnam.

A coordinated international hybrid rice trial in-volved 10 elite hybrids, two international checks,and two national-local checks in six member coun-tries. The trial helped identify specific hybridsadaptable to the countries. These data are beinganalyzed to develop a breeder-friendly selection in-dex using the ranks of mean and cv under low- andhigh-yielding environments.

A benchmark survey in member countries as-sessed their current capacity to develop and use hy-brid rice technology. Good progress was made indeveloping new parental lines useful for developingrice hybrids for the member countries.

Consultancies in collaboration with the Food andAgriculture Organization (FAO) assessed the seedindustry support available for large-scale hybridrice seed production and distribution and gave rec-ommendations for establishment of large-scale seedproduction on a sustainable basis. A consultancyorganized in collaboration with the Asia PacificSeed Association identified policy and institutionalconstraints to development and use of hybrid rice inthe member countries and recommended somepolicy interventions to develop and promote thetechnology.

China was accepted as a full member of the net-work effective January 2000.

Genetic divergence of maintainerand restorer lines used to breedtropical rice bybridsS.S. Virmani, Z.K. Li, Weijun Xu, J.E. Hernandez,1

L.S. Sebastian,1 and E.D. Redoña1

The success of three-line hybrid rice in China sincethe late 1970s is known to be partially due to highlevel of heterosis in crosses between the Chineselocal maintainer lines and the restorers from tropi-cal areas, which are considered to represent twoheterotic groups within indica rice. In order to iden-tify heterotic groups further, IRRI, the University ofthe Philippines Los Baños (UPLB), and PhilRice

Table 4. IRRI breeding lines from the irrigated breedingprogram named as varieties in 1999.

CountryBreeding line Name given where

named

IR35366-90-3-2-1-2 (IR72) Yezin 1 MyanmarIR59606-119-3 OMCS94 VietnamIR61328-1-136-2 Bajo Kaap 2 BhutanIR61331-2-148 Bajo Kaap 1 BhutanIR62032-189-3-2-2 IR62032 VietnamIR62141-114-3-2-2-2 PSBRc80 PhilippinesIR62871-166-2-2 Baghlan 98 AfghanistanIR64446-7-10-5 Dianchao 3 ChinaIR64683-87-2-2-3-3 PSBRc82 Philippines


collaborated to investigate molecular divergence ofsome maintainer and restorer lines of the WA-CMSsystem used in tropical hybrid rice breeding pro-grams.

Thirty-seven simple sequence repeat (SSR)markers distributed in 12 rice chromosomes wereselected for the molecular diversity assay of 37maintainer lines (B) from IRRI and 43 restorer (R)lines from PhilRice. The SSR assays followed thestandard procedure and Nie and Li’s statistic was

Table 5. Microsatellite markers, allele distribution, and gene diversity in parentallines of tropical hybrid rice.

Relative gene diversity

Chromosomea Markers Alleles Within Within Between Totaldetected B lines B and R gene

(no.) lines lines diversity

1 RM1 8 0.25 0.22 0.53 0.77RM5 4 0.25 0.25 0.50 0.69RM212 3 0.07 0.35 0.58 0.35

2 RM6 4 0.11 0.32 0.57 0.45RM221 2 0.18 0.33 0.49 0.07RM250 4 0.10 0.38 0.52 0.13

3 RM16 4 0.11 0.38 0.52 0.23RM22 5 0.19 0.31 0.50 0.20RM168 3 0.22 0.25 0.53 0.56

4 RM226 7 0.22 0.26 0.52 0.71RM241 3 0.23 0.27 0.50 0.40RM261 4 0.20 0.27 0.53 0.62RM255 3 0.36 0.12 0.51 0.19

5 RM164 5 0.25 0.22 0.53 0.69RM13 6 0.18 0.27 0.55 0.63RM122 2 0.22 0.28 0.50 0.34

6 RM3 4 0.16 0.32 0.52 0.23RM30 5 0.25 0.22 0.53 0.56RM217 4 0.21 0.27 0.52 0.63

7 RM10 2 0.19 0.32 0.49 0.13RM11 5 0.21 0.28 0.50 0.22RM18 3 0.24 0.26 0.50 0.54

8 RM25 5 0.20 0.29 0.52 0.60RM80 9 0.25 0.24 0.51 0.69RM42 3 0.24 0.24 0.52 0.45

9 RM215 5 0.24 0.26 0.50 0.37RM201 4 0.18 0.26 0.55 0.53

10 RM216 4 0.25 0.25 0.50 0.62RM228 6 0.24 0.22 0.54 0.78RM258 6 0.24 0.25 0.51 0.69

11 RM167 2 0.27 0.24 0.49 0.09RM254 3 0.26 0.24 0.50 0.61RM209 7 0.10 0.34 0.55 0.49

12 RM19 5 0.24 0.21 0.55 0.70RM17 2 0.12 0.34 0.54 0.32RM12 3 0.12 0.35 0.53 0.31

Unmapped RM15 3 0.14 0.34 0.51 0.18 Av 4.24 0.20 0.28 0.52 0.45 SE 1.71 0.22

aThe assignment of markers on each of the rice chromosomes was based on Chen et al (1997).

used as a measure of genetic similarity. Gene diver-sity was partitioned into B population, within Rpopulation, and between B and R populations.

The mean number of alleles per SSR locus was4.24 ± 1.71, ranging from 2 to 9 (Table 5). Therewere 14 loci where more than five alleles were de-tected. Among 157 detected alleles, 115 (73.2%)alleles were common to both B and R lines, 11alleles at 9 loci were unique to B lines, and 3 allelesat 14 loci were unique in R lines. The frequency of


group-specific alleles ranged from 0.02 to 0.16.Relative gene diversity averaged 0.20 within Blines, 0.28 within R lines, and 0.52 between twogroups of lines, suggesting a significant divergencebetween the parental groups.

Significant allelic frequency differences betweenB and R groups were present for the two most com-mon alleles at a majority of the SSR loci. The meangenetic distance was 0.39 between pairwise B lines,and 0.49 between R lines, indicating the B linesshared greater similarity within group than that ofR lines. This is understandable because, among thetropical indica elite lines, frequency of B lines (lessthan 5%) is much lower than that of R lines (20-30%) for the WA-CMS system.

Cluster analyses were performed based on Nei’sgenetic distances between lines within the B and Rgroups (Figs. 1 and 2). The B lines formed four clus-ters. Cluster A consisted of 33 cultivars (87%).Cluster B contained three closely related lines, B38(IR72081B), B40 (IR64608B), and B16(IR69616B). Cluster C contained only a single lineB39 (IR72082B), which was known to have wide-compatible genes from BPI 76 and Palawan. Theline B2 (IR62829B) formed another single line clus-ter, D. The 43 R lines formed three clusters withcluster A containing 40 most recently developedadvanced lines. Cluster B consisted of only twolines, R54 (C4160-B-3–1) and R7 (MRC 2219-482–156), which are respectively derived fromcrosses of Ostralia/Pinilian and BE-3/BPI 121. Theline R62 (PR23765-23R) formed a single line clus-ter.

Our results indicate a clear differentiation be-tween the B and R lines in tropical hybrid ricebreeding programs. Future research should be devo-ted to increasing diversity among B lines and be-tween B and R lines to broaden the genetic base ofrice hybrids.

Association between SSR diversity,pedigree record, quantitative traitvariation, and hybrid performanceS.S. Virmani, Z.K. Li, Weijun Xu, J.E. Hernandez,1

L.S. Sebastian,1 and E.D. Redoña1

Knowledge of genetic diversity among prospectiveparental lines is important for the success of a hy-brid rice breeding program. Genetic diversity is usu-ally measured using pedigree information, pheno-

B1B6B33B35B24B32B17B18B4B7B10B11B20B21B3B9B14B8B15B28B27B5B34B36B13B22B31B25B37B30B29B38B40B18B39B2

0.32 0.48 0.64 0.80 0.96

B

CD

A

1. Dendrogram of 37 maintainer lines of hybrid rice based onNei and Li distance using UPGMA clustering. IRRI, PhilRice,and UPLB, 1999.

R5R83R72R66R10R63R38R65R18R81R60R33R85R71R64R76R17R13R37R75R13R15R59R56R32R57R58R52R53R61R23R82R28R51R17R36R55R20R29R15R7R51R62

0.32 0.48 0.64 0.80 0.96

BC

A

2. Dendrogram of 43 restorer lines of hybrid rice based on Neiand Li distance using UPGMA clustering. IRRI, PhilRice, andUPLB, 1999.


typic data of plant characteristics, and molecularmarkers. We studied the relationship between thosemeasures and hybrid performance in rice.

Materials used included 37 maintainer and 43restorer lines of the WA-CMS system, which repre-sented germplasm of different origins (IRRI, Philip-pines, and China) used in the hybrid rice breedingprogram of PhilRice, IRRI, and UPLB. The pedi-grees of those parental lines could be traced back toultimate ancestors that had no known pedigree in-formation.

Ten maintainer and 18 restorer lines were ran-domly selected to produce 34 F1 hybrids in 1997.Field evaluation of the hybrids and their parentswere accomplished at three sites in the Philippinesduring 1997 and 1988 DS. Coefficients of co-ances-try were calculated for the parental lines using thepedigree information. Euclidean distances, on theother hand, were derived with data from 12 quanti-tative characters—days to flowering, flagleaf lengthand width (cm), plant height (cm), number of pro-ductive tillers, panicle length (cm), 100-grainweight (g), grain yield per plant (g), grain lengthand width (mm), and panicle weight (g).

SSR assays with 37 primer pairs were made atthe PhilRice Genetic Laboratory and Nei-Li coef-ficients were derived. Correlation analysis betweenvarious diversity measures and hybrid performance,or mid-parent heterosis, was performed on plantheight, grain yield, total plant weight, 100-grainweight, grain length, and grain width.

In analysis of variance across three sites, signi-ficant to highly significant differences were ob-served for all quantitative traits investigated, exceptflagleaf width. The mean number of alleles per SSRlocus was 4.24 ± 1.71, ranging from 2 to 9. Therewere 14 loci where more than five alleles were re-solved.

There was no, or poor, correlation among dif-ferent measurements of diversity for both B and Rlines. These results suggest that the methods formeasuring genetic diversity are not consistently as-sociated with each other.

There was no correlation between the diversitymeasure based on SSR markers and F1 performanceor the midparent heterosis, indicating that molecu-lar diversity at a random set of SSR markers is notuseful in predicting hybrid performance or mid-

parent heterosis. Prediction power may be improvedif selected markers are linked to QTLs affecting het-erosis. Genetic diversity measured by the pedigree-based coefficient of co-ancestry was significantlycorrelated with the F1 mean performance but notwith midparent heterosis for 100-grain weight,grain length, and plant height, which are known tohave high heritability. It appears that pedigree infor-mation can be useful to trace genes of additive ac-tion.

Euclidean distance (D2) estimates based on thequantitative trait differences between the parentswere significantly associated with F1 performancefor plant height and midparent heterosis for the to-tal plant weight, plant yield, and 100-grain weight.

Toward a synthetic apomixis for riceX.Z. Bi, A. Kathiresan, J. Bennett, and G.S. Khush

Cost of seed production limits adoption of hybridrice technology. Whether the three-line or two-linesystem is used, hybridization must occur on thefield scale, where yields are low (typically 1-3 tha–1). Scientists at IRRI and elsewhere have beensearching for several years for apomictic relatives ofrice with the idea that this form of asexual repro-duction could simplify the hybrid rice industry.

If an apomictic mechanism of reproductioncould be activated in a manually produced hybrid,seed could be multiplied asexually in subsequentgenerations without loss of hybridity. Seed pro-duction would be cheaper, more convenient andversatile, and farmers would be able to reproducetheir own apomictic hybrid seed. Apomixis occursin a large number of plant species, including wildrelatives of cereals such as maize, pearl millet, andwheat, but a careful search has failed to reveal anyapomictic rice.

We began exploring the possibility of synthe-sizing a form of apomixis resembling the adven-titious embryony seen in citrus. Although severalapomictic mechanisms exist, the generation of ad-ventitious embryony would in principle require onlytwo steps: 1) induction of an asexual embryo in thenucellar tissue around the embryo sac and 2) re-moval of the sexual embryo. Endosperm productionwould be unaltered.


INDUCING THE ASEXUAL EMBRYO

IN THE RICE NUCELLUS

The nucellus is the large mass of cells surroundingthe embryo sac within the ovary. About 10 d priorto fertilization, a single nucellar cell develops intothe megaspore mother cell and undergoes meiosisand mitosis to form the embryo sac. This sac con-tains eight haploid nuclei, of which one is found inthe egg cell and two are found in the central cell.After pollination, the egg cell is fertilized by onesperm cell and the central cell is fertilized by a sec-ond sperm cell. The embryo develops from the fer-tilized egg and the endosperm develops from thefertilized central cell.

At about the time of fertilization, the nucellusbegins to undergo programmed cell death (PCD) tosupply the young zygotic embryo and the youngendosperm with nutrients. This time would also besuitable for the start of adventitious embryo forma-tion.

We sought to isolate a rice promoter that couldtrigger embryogenesis in the nucellus. The nucellingene of barley is expressed exclusively in the nucel-lus, starting about 1 d prior to fertilization. It ap-pears to encode an aspartate protease involved inPCD. We used published data on that gene to iso-late the rice homologue by a technique based on thepolymerase chain reaction (PCR).

Basing our PCR primer design on those seg-ments of the barley nucellin gene that show its rela-tionship to aspartate proteases, we used reversetranscriptase-PCR (RT-PCR) to amplify a partialcomplementary DNA (cDNA) from RNA isolatedfrom the ovary 1 d prior to fertilization. The se-quence of the cDNA fragment confirmed its rela-tionship to barley nucellin.

We used the rice cDNA fragment to determinegene copy number and found only a single copy ofthis gene. Mapping of the gene using the IR64/Azucena mapping population showed that it is lo-cated on chromosome 11. We used the cDNA probeto isolate a series of clones from the IRRI library ofbacterial artificial chromosomes (BAC) derivedfrom IR64 DNA. The clones all proved to containthe same gene, which has now been sequenced from>3 kb upstream to >0.5 kb downstream of thenucellin coding sequence. The upstream sequencewill presumably contain the desired promoter.

RT-PCR of RNA isolated from a range of ricetissues and from the panicle at various stages of de-velopment established that it is ovary-specific andexpressed from about 1 d before fertilization to atleast 5 d after fertilization. Preliminary in situ hy-bridization with a fluorescent anti-sense probe de-rived from the 3’-untranslated region (3’UTR) ofthe nucellin gene showed that the gene is indeedexpressed in the nucellus (Fig. 3).

The next step is to splice the nucellin promoterwith the coding regions of rice homologues of genesimplicated in inducing embryogenesis inArabidopsis (e.g., lec1 and mi-2). The resulting con-structs will then be introduced into rice to determinewhether they induce adventitious embryony.

ARRESTING THE SEXUAL EMBRYO DEVELOPMENT

The simplest way of arresting the development ofthe sexual embryo is to generate an inhibitory pro-tein under the control of an egg- or zygote-specificpromoter. Because such a promoter is to date un-known for plants, we took a more involved (two-gene) approach to achieve the same goal. In thisapproach, we required two promoters—one ex-pressed specifically during meiosis and another ex-pressed during early embryo development. Themeiosis-specific promoter is required to activate theembryo-specific promoter only in embryos derivedfrom meiosis (sexual embryo). As the adventitious

3. In situ hybridization of rice ovary tissue (5 d after fertilization)with nucellin cDNA. Paraffin-embedded ovary sections (8 µm)were probed with DIG-labeled sense (A) and antisense (B) RNAtranscribed from a 363-bp nucellin cDNA fragment. IRRI, 1999.

A B


4. Expression profile for rice DMC1B. Embryogenic calli, leaves, and roots from3-wk-old seedlings, and various lengths of panicles from primary tillers of IR64were harvested. RT-PCR was done using 1 mg DNase-treated total RNA each astemplate and DMC1B sequence-specific primers. The primers flank two intronstotaling a size of 511 bp. The expected size of RT-PCR product is 553 bp and thatof the genomic product is 1064 bp. IRRI, 1999.

embryo is derived from nonmeiotic cells, its devel-opment should not be arrested by this mechanism.

Following a published report that theArabidopsis recA homologue DMC1 is meiosis-specific, we decided to clone and characterize riceDMC1. Based on Genbank sequence data, we de-signed primers complementary to DMC1 and am-plified a rice genomic fragment. Southern blottingwith this partial fragment showed that the rice ge-nome contains two copies of DMC1. We isolatedand sequenced both copies (DMC1A and DMC1B)from IR64 BAC library. At the nucleotide level, thetwo DMC1 copies show 97.4% identity for codingregions and 70% identity for 3'-UTR. RT-PCRshowed that although expression of both copies co-incides with meiosis in panicles, they are also ex-pressed in mitotically active cells such as calli. Fig-ure 4 shows the data for DMC1B.

It is clear that DMC1 in plants is not strictlymeiosis-specific, unlike homologues in yeast andanimals. We are now exploring the potential utilityof the rice homologue of SPO11, another meiosis-specific protein of yeast (type II topoisomerasesubunit).

For a promoter that is embryo-specific amongpost-meiotic cells, we turned to REE5, a 254-bp ricecDNA clone isolated from zygotic embryos. REE5-specific primers and DNA gel blots showed that therice genome contains at least two REE5-like genes.To generate gene-specific probes, we cloned the 3’-UTR of REE5 that is expressed in spikelets 2 d af-ter fertilization through rapid amplification of3'cDNA ends (3'-RACE). Using the 3'-UTR of theRACE clone, we screened IR36 lambda genomiclibrary and subcloned a 5.0-kb HindIII fragment.Sequence analyses suggested that REE5 encodes anovel phosphoprotein. We are currently determin-ing its expression pattern in rice ovules.

1 Kb

600 bp

1 K

b pl

us0-

34-

67-

910

-12

13-1

516

-18

19-2

122

-24

calli

leav

esro

ots

dWat

erIR

72 g

enom

eB

AC

clo

ne (

DM

CIE

)10

0 bp

ladd

er


Characterization of root systemin a new plant typeS. Kubota, H. Samejima,2 E. Laureles, and O. Ito

A vigorous root system has been given as one ofselection criteria in breeding of the NPT, but its rootsystem has not been studied in detail. There is noevidence to show morphological and physiologicalsuperiority of NPT’s root system over existing IRRIvarieties.

A 1997 WS field experiment at IRRI examinedroot systems. Seedlings (14 d old) of IR72 and NPT(IR65598-112-2) were transplanted on 27 Jun. Fer-tilizers were applied 1 d before transplanting as abasal application of 150 kg N ha–1, 60 kg P ha–1 and60 kg K ha–1 combined with four types of slow-re-lease coated urea—LP40, LP70, LP100, andLP140. Plant density was 25 hills m–2 for IR72 and50 hills m–2 for NPT. Root samples of 1 hill of IR72and 2 hills of NPT were taken by a monolith (20 cm× 20 cm × 50 cm) at 3-wk intervals from trans-planting to panicle initiation (PI), and at 2-wk inter-vals from PI onward.

The soil and roots inside the monolith were di-vided into six horizons—0–2, 2–5, 5–10, 10–20,20–30, and 30–40 cm from the soil surface. Col-lected roots were washed and measured by imageanalysis. Stem sap was sampled at 35, 46, 61, 76,90, and 104 d after transplanting (DAT). Four hillsof each plot were cut at 15 cm height at 1800 h onthe sunny day and absorbent cotton was put on eachstump until 0600 h the next morning. The cottonwas covered with a plastic bag and a black plasticpot to avoid vaporization and night dew. Amount ofstem sap was estimated by weighing the cottons.Eight hills were harvested for the measurement ofyield and yield components and grain yield was ad-justed to 14% moisture content.

Total dry matter at harvest was larger in NPTthan in IR72. IR72 had significantly larger paniclenumber, higher grain filling, and larger 1,000-grainweight than NPT. On the other hand, number ofgrains was larger for NPT than for IR72. There con-sequently was no significant difference betweenIR72 and NPT in rice yield.

Total root length was longer in NPT than in IR72throughout the growth stage (Fig. 5) and NPT re-corded maximum root length (ML) two timeslonger than IR72 at 55 DAT. After 55 DAT, NPTshowed a sharp decline in root length. The length

decreased by 50% of ML at flowering (FL), fol-lowed by further reduction. In contrast, IR72 flow-ered at 6 d after ML, resulting in slower reductionin length than NPT at FL. Changes in total root dryweight (DW) of both varieties were almost identi-cal with the changes in root length (Fig. 6). The rootDW was significantly larger in NPT than in IR72.Difference in the DW was particularly obvious at 0–2 cm and 2–5 cm of soil profiles, suggesting thatNPT developed a vigorous root system in relativelyshallow soil profiles.

40

30

20

10

0

MT and PI

FL

MTFL

PI

0 30 60 90 120

NPTIR72

Days after transplanting

Root length (km m-2)

5. Changes in root length of NPT and IR72. IRRI, 1997 WS.

6. Changes in root dry weight of whole root and each soil profilein NPT and IR72. IRRI, 1997 WS.

5-10 cm40302010

0

2-5 cm40302010

0

Days after transplanting0 30 60 90 120

10-20 cm302010

00 30 60 90 120

Below 20 cm302010

0

0-2 cm605040302010

0

120100

80604020

0

Whole root

NPT

IR72

Root dry weight (g m-2)


Table 6. Plant characteristics and grain yield of promising elite lines developed from japonicagermplasm at IRRI during 1992-99. IRRI, 1999.

1999 DS 1999 WS

Line HDa PLb NPc Yield HD PL NP Yield(d) (cm) (no. hill–1) t ha–1) (d) (cm) (no. hill–1) (t ha–1)

IR68333-R-R-B-22 74 20.4 10.9 7.2 76 18.3 10.6 4.6IR68349-131-2-2-3 64 20.1 9.4 6.0 68 18.5 11.0 4.7IR68352-14-1-1-1 62 20.1 10.1 6.6 68 18.7 10.3 4.8IR68399-78-2-3-3-1 62 22.4 8.9 6.4 74 19.7 10.0 4.4IR68373-R-R-B-22-2-2 68 20.0 10.3 6.0 72 19.4 9.8 4.7Jinmibyeo check) 70 20.1 9.8 5.6 68 19.4 11.1 4.1

aHd = heading date. bPL = panicle length. cNP = no. of panicles.

NPT

FL

IR72

FL

600

500

400

300

200

100

0

Amount of stem sap (g m-2)

0 20 40 60 80 100 120

Days after transplanting

7. Changes in the amount of stem sap in NPT and IR72. IRRI,1997 WS.

IR72 recorded 300 to 380 g m–2 of stem sap until62 DAT, which was just before FL. Stem sap lin-early decreased after FL (Fig. 7). NPT showed themaximum amount of 570 g m–2 at 46 DAT, whichwas 40 d before FL. Decline in stem sap in NPTstarted during the vegetative stage and decreased byan estimated 200 g m–2 at FL.

This study indicates that the root system andstem sap as an index of root function in NPT is su-perior to IR72 at the early vegetative stage, but se-nescence of the root system begins earlier in NPT,resulting in poor root activities during the reproduc-tive stage.

Japonica germplasm utilizationfor value addedM.H. Lee, J.R.T. Chavez, and G.S. Khush

Since 1992, 475 IR designated crosses have beenselected as advanced generations in research to de-velop japonica germplasm for use in the tropics.More than 3,000 pedigree lines were maintainedeach season to accommodate breeding selectionpressures.

Grain yield improved gradually from a fluctuat-ing low potential yield of 3 t ha–1 to an average ofmore than 5 t ha–1. Twenty-five elite lines weretested at IRRI during 1999. Five of those lines hadyield equal to, or greater than, yield of the checkvariety (Table 6). These new elite lines are adaptedto tropical cultural management. Entries were sentto the International Network for Genetic Evaluationof Rice (INGER) and PhilRice to test their yieldpotential in different tropical regions.

Inheritance of RTSV resistance in TW5,the near-isogenic line from Utri MerahO. Azzam, T. Imbe, R. Ikeda, P.D. Nath,3 M. Muhsin,4 and E. Coloquio

Adaptation in green leafhopper populations and thepresence of virus variants for the RNA (rice tungrospherical virus [RTSV]) and DNA (rice tungrobacilliform virus [RTBV]) viruses of tungro, sug-gest that tungro resistance, when deployed, will beeasily overcome. Hence, an integrated approach for


combining several sources of resistance may be ef-fective in tungro management. Understanding themode of inheritance of currently available tungroresistance genes will allow integration of a diversi-fied type of resistance. Utri Merah (IRGC 16680and referred to as UM80) is highly resistant toRTSV and tolerant of RTBV in artificial inoculationand field evaluation. Analysis of a large number ofF3 progenies derived from UM80/TN1 revealed thatUM80 may have two independent recessive genesto RTSV (tsv-1 and tsv-2). In addition, the near-isogenic lines (TW5 and TW6), which were derivedby backcrossing UM80 with IR22, a recurrenttungro-susceptible parent, also showed resistance totungro infection by artificial inoculation. Based ontheir reaction with different RTSV variants, TW5and TW6 were thought to have the recessive genetsv-1.

We studied the inheritance of that gene using F3progenies of TW5/TN1 combination and two RTSVvariants: RTBV + RTSV-V and RTSV-VI. The in-oculation conditions were standardized and theRTSV inocula were monitored by enzyme-linkedimmunosorbent assay (ELISA) and RT-PCR to en-sure the quality and type of inoculum. Thirty plantsper line were insect-inoculated and their reactionwas evaluated at 3 wk post inoculation by ELISA.The F3 analysis of 203 lines inoculated with RTBV+ RTSV-V inoculum showed complete suscep-tibility to RTBV infection and a segregation ofRTSV resistance into 13 resistant lines and 190 seg-regating and susceptible lines, resulting in a good fitto a 1:15 ratio rather than to a 1:3 as expected.

These results triggered the retesting of the F3lines with RTSV-VI, the avirulent RTSV inoculumsource that is maintained on TN1 plants.

Among 203 progenies, 118 were insect-ino-culated and evaluated by ELISA for their resistanceto the virus. Results showed that the F3 progeniessegregated into 34 resistant lines and 84 segregat-ing and susceptible lines, resulting in a good fit to a1:3 ratio. These results suggest that the inheritanceof resistance to RTSV in TW5 depends on the na-ture of RTSV inoculum used.

Because of the differential reaction of TW5/TN1F3 progenies to two RTSV inocula, the evolutionaryrelationships between RTSV variants were eval-uated using sequence analysis of the amplified RT-PCR coat protein region of the RTSV genome (nt

2453-3607). The currently used RTSV-V andRTSV-VI inocula and their corresponding 1997 and1996 purified virus stocks were included. In addi-tion, the sequence of the original RTSV avirulentsource (PgA) and that of the current RTSV-Vt6(PgVt6-III) were also used.

For general comparison, field RTSV isolateswere included when phylogenetic grouping was at-tempted with the parsimony method. The tree gen-erated for the coat protein nucleotide sequencealignment revealed a separate clustering for each ofthe four RTSV variants found at IRRI greenhouse(Fig. 8). Although Pg16VI and Pg08V variants wereoriginally derived from PgA, the current data showthat they are distinct variants. These results confirmthat RTSV inoculum maintained with RTBV sourceon TN1 differs from the one maintained alone onthe same host.

Breeding rice for resistance to tungroG.S. Khush, E.R. Angeles, A.M. Pamplona,and P.S. Virk

Resistance to tungro has always been emphasized inIRRI’s breeding program. Most of the IR varietiesdeveloped to date have resistance to green leaf-

8. Parsimony tree for RTSV coat protein sequence alignments(1.1 kb) of IRRI greenhouse and field isolates in the Philippines.Pg = IRRI-greenhouse isolates; Pc = isolates from northCotabato, Pe = isolates from Nueva Ecija. PgA = RTSV-avilurent strain sequenced in 1988; PgVt6 = RTSV-virulentsource on TKM6 sequenced in 1996; Pg16VI and 09VI = RTSV-avirulent source on TN1; Pg08V and Pg05V = tungro source onTN1. IRRI, 1999.

4880

96

99

9874

100

99

72

52

34

100

89

80

Pg16VI, 1999

Pg09VI, purified virus stock-1996Pc03VPg08V, 1999

PgA, 1988

Pe21IIPc88II

Pc41IIPc20IPc34I

P71III

Pc17IIIPc46III

Pc12V

Pg05V, purified virus stock-1997

PgVt6-lll, 1994

CP1-CP2- 1.1kb


hopper, the vector of the tungro virus. However, thevector resistance erodes after several years. Wehave tried for the last 10 years to develop improvedgermplasm with resistance to the virus.

Several donors for resistance were used, such asHabiganj DW8 from Bangladesh, Utri Merah andUtri Rajapan from Indonesia, and Oryza rufipogon.Donors were crossed with improved-plant-typelines susceptible to green leafhopper, and severalbackcrosses made. We were able, in the absence ofvector resistance, to select for tungro resistance inthe segregating generations. Several lines with vi-rus resistance were selected from the crosses of eachof the donors (Table 7). These lines have high yieldpotential, excellent grain quality, and short growthduration. They were tested for tungro resistance atMidsayap, Mindanao, Philippines, where tungro in-cidence is always high and showed tungro resist-ance. Evaluation with ELISA shows that these linesare resistant to RTSV.

Table 7. Elite tungro-resistant lines developed fromcrosses with donors of tungro resistance and improvedplant types. IRRI, 1999.

Donor for GrowthSelection resistance duration

(d)

IR71606-1-1-4-2-3-1-2 Habiganj DW8 116IR71606-1-2-1-3-2-3-1 Habiganj DW8 116IR73885-1-4-3-2-1-4 O. rufipogon 119IR73885-1-4-3-2-1-6 O. rufipogon 120IR73885-1-4-3-2-1-10 O. rufipogon 118IR73888-1-2-7 O. rufipogon 120IR69726-41-2-3 Utri Merah 123IR69726-41-2-3 Utri Merah 127IR70458-87-2-2-3-1 Utri Rajapan 132IR69727-37-2-1-3-2 Utri Rajapan 118IR72 (check) None 122

menon in long-term experiments (LTE) in Asia, weanalyzed data from 30 LTEs at 24 different sites inChina, India, Indonesia, Bangladesh, Vietnam, Phil-ippines, and Malaysia. The data represent a varietyof soil types and constitute all the experiments forwhich we were able to obtain data sets (data for oneparticular season) for at least 9 years. Twenty-twoLTEs were from rice monoculture systems. Eightrice-upland crop LTEs included five rice-wheatsites and three experiments with triple-cropping—rice-rice-wheat (Sichuan), rice-rice-barley(Zhejiang),and rice-wheat-jute (Barrackpore).

The only data included in the analysis are thosefrom the treatment with the NPK rate that con-sistently produced the highest yield. Rice varietiesused in all LTEs were modern varieties with a har-vest index of 0.45–0.50 and a growth duration of110–130 d. Transplanting was used for rice cropestablishment. Yields were measured from a 4- to5-m2 harvest area in each replicate plot per treat-ment. Soil and plant data were collected over time,but had widely differing frequencies and samplingand measurement procedures, and are not includedin the formal statistical analysis. However, they areused in the interpretation of the results where appro-priate.

To test the hypothesis that yield trends over aperiod of at least 9 years are significantly differentfrom zero, data were analyzed by ordinary leastsquares linear regression of yields (in logarithmicform) against a time trend variable:

ln(Y) = a + bt

where Y is the grain yield (kg ha–1), a is a constant, tis the year, and b is the slope or magnitude of theyield trend (percentage change in yield per year). Astatistically significant positive or negative yieldtrend was recorded only if the null hypothesis of azero slope for the time trend variable could be re-jected at a 5% level of significance (two-tail test).The WS and DS data were analyzed separately.

Only two of the 21 data sets from the 15 sitesoutside of IRRI showed declining DS yield trendsthat were statistically different from zero at a 5%level of significance or less. Eight of these 21 datasets showed positive yield trends, with one statis-tically different from zero (Omon-LTFE, +4.63%y–1). In contrast, DS experiments at IRRI had statis-

Sustaining soil quality in intensiverice systems

Yield declines in long-term rice experimentsin AsiaD. Dawe, A. Dobermann, P. Moya,S. Abdulrachman,5 Bijay-Singh,14 P. Lal,7

S.Y. Li,17 B. Lin,19 G. Panaullah,20 O. Sariam,21

Y. Singh,7 A. Swarup,18 P.S. Tan,22

and Q.-X. Zhen23

Yield declines are an important phenomenon atIRRI. To investigate how widespread this pheno-


tically significant yield declines ranging from –1.45% to –1.61% y–1.

High DS grain yields of 7–8 t ha–1, with no sub-stantial decline over time, were measured in the fourLTEs at the PhilRice and Bicol, Philippines, sites.By the late 1980s, yields in those experiments ex-ceeded those in comparable experiments at IRRI by1 t ha–1, although yields at the IRRI experiments hadstarted out at higher levels. The DS Omon-LTFEexperiment that showed a statistically significantpositive yield trend started on a P-deficient, acid-sulfate-influenced soil and regular P addition hasbeen the main factor causing the yield increase.

In the WS, two of the 14 data sets from 11 sitesoutside of IRRI showed a statistically significantdeclining yield trend—the PhilRice LTFE (–1.35%y–1) and the Omon-LTFE (–2.22% y–1). Four ofthese 14 data sets showed positive yield trends, al-though none were statistically significant. In con-trast, all four WS data sets at IRRI showed yielddeclines, and three of them were statistically signifi-cant. Yield declines appear to be more common inthe WS, although most of these declines are not sta-tistically significant.

Of the eight rice-upland crop LTEs, there was astatistically significant yield decline in only one of10 rice data sets—the Pantnagar-LTFE (–2.3% y–1).The rice crop at the Ludhiana-LTE suffered a sub-stantial yield decline of –2.7% y–1, but it was notstatistically significant and 2 of the years with lowyields were due to pest outbreaks. In all other LTEs,rice yields in the best fertilizer treatments remainedvirtually unchanged over periods of 10–25 years.Four of the 10 data sets showed positive yieldtrends, and the average yield trend was relativelysmall at just –0.45% y–1. Of the seven wheat datasets, there were no statistically significant yield de-clines, but one statistically significant yield increaseoccurred in the Pantnagar LTE (+2.4% y–1). Threeof the seven data sets showed a positive yield trend,and the average yield trend was slightly positive at+0.04% y–1.

On the sodic soil of the Karnal-LTE, high riceyields of about 7 t ha–1 and wheat yields of about 5 tha–1 were sustained for 12 years, and continuousrice-wheat cropping decreased the soil pH from 9.2to 8.5. The Nangong-LTE is noted because of highrice yields (6–8 t ha–1) sustained for 14 years. TheSichuan-LTE with three crops grown per year (rice-rice-wheat), where annual grain production was

sustained at a level of 15 t ha–1 for 10 years, had nodistinct trend of a decline or increase.

Our results question whether the yield declinesobserved in various LTEs at IRRI are currently rep-resentative of other irrigated rice areas in Asia. Nev-ertheless, yield declines do occur in some LTEs, andtheir causes must be understood. Based on a reviewof the evidence from these LTEs, several possibleimportant causes stand out.

● One possibility is a decline in indigenous Nsupply associated with increased phenol con-tent of soil organic matter (SOM). That couldabiotically immobilize N or reduce the rate ofN mineralization per unit of organicallybound N. With increased frequency of crop-ping (longer anaerobic vs aerobic periods),more partly degraded lignin residues accumu-late, the phenolic content of SOM increases,and the degree of humification of SOM de-creases. The IRRI-LTCCE, with short andwet fallow periods, might represent the mostextreme case of such SOM changes. For ex-ample, a long, dry fallow period occurs atPhilRice before the DS, whereas soil dryingin this period is much less intense at IRRI.This difference may explain why there was nosignificant decline in DS rice yields atPhilRice but a significant decline in all DSexperiments conducted at IRRI.

● Phosphorus deficiency in the form of low ini-tial available soil P, or a negative P balance,appears to have contributed to yield declinesin several LTEs, including Luisiana,Pantnagar, Shipai, Jinxian, and Omon.

● In several LTEs, fertilizer K rates were notsufficient to sustain a neutral or positive Kinput-output balance so that soil K depletionoccurred, often much below a commonlyused critical level (1 N NH4OAc-extractableK) of 0.2 cmolc kg–1. Such LTEs includeGazipur, PhilRice, Pantnagar, Jinxian, andShipai. Available information suggests thatthe K rates used in many LTEs were sufficientin the initial years, but not after a period ofdecline in soil K reserves.

● A decline in the quantity of SOM may also bean important factor in some rice-upland cropLTEs (e.g., Pantnagar), but this appears not tobe a serious issue in rice monoculture LTEs.


Prolonged submergence, insufficient soil dryingduring fallow periods, and soil P depletion or soil Kdepletion, or both, were associated with many of theyield declines that did occur. If gradual changes insoil nutrient supply or root nutrient uptake aremainly driven by oxygen and carbon supply, theycould be generic in nature for particular croppingsystems. Yield declines caused by nutrient miningare less troublesome because they can be correctedmore easily. The proper interpretation of futureLTEs will require more detailed measurements thanhave been done in the past

Improving the productivity andsustainability of rice-wheat systems

Improving rice-wheat systemsThe rice-wheat production system in the Asian sub-tropics occupies nearly 24 million ha in South Asiaand another 10.5 million ha in central China. Thefavorable production environment has inducedfarmers to use a highly intensified production sys-tem with increased use of chemical fertilizers andpesticides. Those contributed to an impressive in-crease in per capita cereal production in the regionduring 1965-85.

The 1965-85 gains in per capita cereal produc-tion from the rice-wheat system are threatened bystagnant yields of both rice and wheat and a dec-lining trend in total factor productivity. The declinein SOM, imbalances of soil nutrients, the loweringof groundwater tables, and buildup of insect anddisease pressures are indicators of the threat tosustainability of the system.

The Rice-Wheat Consortium for the Indo-Gangetic Plains was formed in 1994. Bangladesh,India, Nepal, and Pakistan provide the leadership inpartnership with IRRI, the International Maize andWheat Improvement Center (CIMMYT), the Inter-national Crops Research Institute for the Semi-AridTropics (ICRISAT), and the International IrrigationManagement Institute (IIMI).

Ecoregional approach to natural resourcemanagementR. Roetter, P.K. Aggarwal,6 N. Kalra,6

A.G. Laborte, and C.T. Hoanh

New approaches and methods are being developedfor research at the systems level to project future

food demand in relation to nutrient managementand possible effects on environment. IRRI’s Sys-tems Research Network for Ecoregional Land UsePlanning in Tropical Asia (SysNet) aims to developand evaluate methodologies for exploring land useoptions at the subnational level. For that purpose,regional case studies were set up in Haryana State(India), Kedah-Perlis Region (Malaysia), IlocosNorte Province (Philippines), and Can Tho Prov-ince (Vietnam).

During a stakeholder-scientist workshop forHaryana in March 1999, various scenarios were for-mulated and analyzed. Stakeholders gave the fol-lowing priority objectives:

● Double food production for Haryana.● Maximize agricultural production while set-

ting limits on labor migration. In the future,the supply of labor from outside Haryana maybe more restricted.

● Minimize nitrogen loss.● Minimize pesticide residues.● Improve water management-intervention

measures to reduce groundwater depletion.● Maximize income from agriculture.Initial explorations for the scenario to maximize

food production suggest that, with currently availa-ble land and water, annual cereal production couldbe increased to 16 million t (currently 10.7 milliont) if appropriate technologies were adopted by farm-ers. When actual capital and labor were taken intoaccount as constraints, the result did not change,which indicates that water is the most limiting fac-tor. The scenarios assume that improved technolo-gies that lead to increased fertilizer and water useefficiency can be applied.

We used five levels of technology that led to dif-ferent efficiencies of nutrient use. With technologylevel 5 (N use efficiency 75% for wheat), the ferti-lizer requirement (200–250 kg ha–1) and leachinglosses of N (10% of applied N) are lower for achiev-ing the maximum attainable (90% of potential)yield, but this requires extra capital for procuringthe inputs. At the current technology level (N useefficiency 50% for wheat), however, the existinginputs will do, but fertilizer requirements (400–500kg ha–1) as well as leaching losses of N (25–30% ofapplied N) will be high for the same target yield.With current technology (average farmers’ practice)and current input use, the model suggested foodproduction 10% higher than it is now being


achieved. This shows the potential of the model todevelop, analyze, and optimize different scenariosalong with their impacts on food production, re-quired resources, production technologies, and en-vironmental consequences to help stakeholdersidentify feasible solutions and select the best option.

Soil- and seedborne pathogens of rice in arice-wheat systemL. Willocquet, S. Savary, A. Kumar,7

and U.S. Singh7

Pests (insects, weeds, pathogens) are an importantcomponent for sustainability of the rice-wheat sys-tem and soil- and seedborne pathogens may play aspecific role. Cropping practices may affect the dy-namics of those pathogens, both for their survivaland their epidemic phases. Interaction amongpathogens may also alter the patterns of diseases ina given field.

FIELD SAMPLING AND DISEASE ASSESSMENT

Quantification of disease incidence due to soilborneand seedborne pathogens was done in farmers’fields. Pathogens included sheath blight (ShB,Rhizoctonia solani), stem rot (SR, Sclerotiumoryzae), brown spot (BS, Cochliobolusmiyabeanus), sheath rot (ShR, Sarocladiumoryzae), panicle blast (PB, Pyricularia grisea),crown sheath rot (CShR, Gaeumannomycesgraminis), and false smut (FS, Ustilaginoideavirens). Some (BS, ShR, PB, CShR) can be trans-mitted by seeds. Others (ShB, SR, BS, PB, CShR,FS) survive as propagules in the soil or in plant de-bris. Glume discoloration was also condidered be-cause it is associated with the presence of differentfungi, among which are P. grisea and C.miyabeanus.

Assessments were done in eight fields selected torepresent a range of crops preceding rice. We moni-tored two fields with wheat (B3 and B6), one fieldwith rice (B4), one field with sorghum (B1), onefield with maize (PP5), one field with lentil (B9),one field with a fallow (PP2), and one field withmint (PP3) as a crop preceding rice.

Disease assessments were done at milk stage bya 20-hill sample. Total number of tillers, number oftillers infected by ShB, SR, BS, and CShR, total

number of panicles, number of panicles infected byShR, PB, and FS, and number of panicles showingglume discoloration were recorded for each hill.

DISEASE INCIDENCE IN FARMERS’ FIELDS

SB, SR, ShB, BS, SHR and glume discolorationwere observed in all fields (Fig. 9). The other dis-eases, when present, occurred at low incidences (0-8%) and were not considered for multivariate analy-ses (see below). Highest incidences were observedfor SB (up to 68%) and BS (up to 85%), whereasShR incidence remained below 20% in all the fields.

Sheath blight incidence was relatively high in allthe fields (around 20%) and reached 75% in fieldPP5. Brown spot incidence varied from 8 to 90%among fields. Stem rot was also extremely variabletoo, but within a smaller range of incidence(2–35%). Sheath rot was observed in all fields, butat low incidence. Glume discoloration incidencewas around 25% in all fields except B4 and PP5,which had lower levels.

Pearson coefficients of correlation were com-puted based on the disease incidence data collected

9. Fraction of infected tillers or panicles in eight farmers’fields under rice-wheat in West Uttar Pradesh, India,1999.

0.6

0.4

0.2

0

B9 PP2

CS

hR

ShB

SR

ShR

PB

FS

GD

BS

PP50.8

0.6

0.4

0.2

0

PP3

CS

hR

ShB

SR

ShR

PB

FS

GD

BS

0.8

0.6

0.4

0.2

0

B1 B3

Fraction of infected tillers or panicles

0.4

0.2

0

B4 B6


BSGD

ShR

SRShB

1.0

0.5

0.0

-0.5

-1.0-1.0 -0.5 0.0 0.5 1.0

Factor 2

Factor 1

Factor 3

BS

GD

ShR

SR

ShB

-1.0 -0.5 0.0 0.5 1.0Factor 1

Factor 3

BS

GD

ShR

SR

ShB

-1.0 -0.5 0.0 0.5 1.0

Factor 2

at the hill scale. Sheath blight and SR were nega-tively correlated (–0.388; P<0.001), and BS waspositively correlated with glume discoloration(+0.19; P=0.013). Panicle blast correlated positivelywith SB, negatively with SR, and negatively withglume discoloration, but those correlations shouldbe interpreted cautiously, given the low levels of PBencountered.

RESULTS FROM A PRINCIPAL COMPONENT ANALYSIS

A principal component analysis was done based onthe disease incidence data collected at the hill level(Fig. 10). The two first axes explained 54% of thetotal variability. The third axis explained 19% of thetotal variability. The first axis mainly reflects astrong opposition between SB and SR incidence.Axis 2 reflects the association between glume dis-coloration and BS. Axis 3 reflects the oppositionbetween ShR and BS.

INTERPRETATION OF TRENDS

Our preliminary results point at trends that must beinterpreted with caution, given the small number ofsampled fields:

● SB and SR appear to be negatively correlated.This may be due to differences in environ-ments that favor these two diseases, or tocompetition between the two types of propa-gules, or both.

● Glume discoloration is correlated with BS.Indeed, C. miyabeanus is reported as a fungusassociated with glume discoloration.

● Sheath rot seems negatively associated withBS but that must be further documented.

● Linkages between rotations and disease lev-els can be cautiously hypothesized because ofsmall number of fields monitored. For in-stance, field PP5 shows the ShB level nearlytwice that of other fields. PP5 was previouslyplanted with maize, which can host R. solaniAG 1–1A. The effect of a maize-rice systemon ShB blight must be further documented.

Improving pest management

Determinants of farmers’ pest managementdecisionsK.L. Heong

Farmers make decisions on pest managementpractices every season. Those decisions often seemto lack economic rationality. We introduced twoconcepts from social psychology to gain better un-derstanding of the determinants of farmers’ stemborer management decisions: 1) the pest beliefmodel and 2) Fishbein and Ajzen’s theory of rea-soned action.

Farmers spent an average of US$39 ha–1 on in-secticides, believing that they would lose an aver-age of 1,004 kg ha–1 or US$402 if no action wastaken. Farmers’ estimates of the worst attack lossfrom stem borers averaged 1,038 kg ha–1 orUS$415, which was similar to farmers’ loss esti-mates for last season. This implied that farmers’decisions were based on preventing the worst case

10. Output of the principal component analysis on incidence of different diseases in eight farmers’ fields.IRRI, 1999.


occurring. However, farmers’ estimates of the high-est number of whiteheads averaged 19 whiteheadsm–2 and the loss computed from known agronomiccharacteristics of IR64, the most commonly plantedvariety, was only 351 kg ha–1 valued at US$140 ha–

1. We found that more than 50% of the farmers spentmore than US$18 ha–1 on stem borer control andexpected to prevent a loss equivalent to $237 ha–1,a cost-benefit ratio of 1:13. The cost-benefit fromthe worst infestation was only 1:4, implying thatfarmers’ perceived benefits were about three timeshigher than the worst case.

Perceived benefits from insecticides were di-rectly related with farmers’ insecticide use and per-ceived severity. Perceived susceptibility was alsohigh, with 59% of farmers believing that a loss of450 kg ha–1 would be likely. Farmers believed in-secticides could destroy natural enemies but placedonly moderate importance on conserving them. Hu-man health was believed to be important but farm-ers had mixed beliefs that spraying could cause poorhealth.

This study also provided evidence suggestinghigh peer pressure on farmers’ spray decisions,which directly influenced perceived benefits fromsprays, insecticide expenditures, and spray fre-quency.

Field evaluation of prototypeTungro Screen B kitsO. Azzam, P. Nath,4 P. Cabauatan, R. Cabunagan,T. Chancellor, and L. Kenyon8

A diagnostic screen kit was successfully developedfor RTBV (Fig. 11) and tested by collaborators inBangladesh, India, Indonesia, and Philippines. En-couraging results were obtained. Collaborators were asked to complete a ques-tionnaire on the utility of the kit after completing theindexing of rice samples for the presence of RTBV.Based on their responses, the prototype kit was thenmodified to improve its efficacy.

The kit was field-tested in July 1999 at six sitesin north Cotabato, Philippines. Rice stems fromplants at different growth stages were collectedfrom six known and three unknown varieties andtested locally. Plant material was retained for latertesting by DAS ELISA at IRRI. There was a highlevel of similarity in the scoring of the membranes

by different assessors, with between 83% and 89%of the positive assessments from the kit also posi-tive for RTBV in DAS ELISA tests. The kit had agood degree of accuracy, which can be improvedwith further refinement of the method. The methodis sufficiently robust to be used outside the labora-tory and simple enough to be used by persons afterlimited training.

Alternative prey in irrigated rice: implicationsfor biological control of hoppersL. Sigsgaard, S. Toft,9 and S. Villareal

The sheet web spider (Atypena formosana) is themost important linyphiid in the rice ecosystem.Adults and immature spiders prefer to live in the

11. An example of a tissue printing blot for field testingof rice samples collected from North Cotabato, Philip-pines, in July 1999. The prints were scored based on thepositive (+) and negative (–) reference checks found atthe bottom of the page. IRRI, 1999.


rice stem or at the base of rice hills, where they huntfor nymphs of planthoppers and leafhoppers, col-lembola, and small dipterans.

The sheet web spider and the wolf spider(Pardosa pseudoannulata) are the dominant pre-dators in rice until about 35 DAT in the Philippines.Indirect evidence of A. formosana’s associationwith brown planthopper (BPH) and green leaf-hopper (GLH) is that populations fluctuate with thedensities of BPH, GLH, whitebacked planthopper,and all other hoppers.

Previous research at IRRI suggests that spiderscan make a significant contribution to a reduction inthe number of BPH and GLH, if there is a high den-sity of predators in the field early in the croppingseason.

We made a laboratory assessment of the survivaland development time of A. formosana juveniles ondifferent diets that represented the most commonprey in the field. We tested the hypothesis that dif-ferences in diets would have different effects ontheir survival.

Survival and development differed significantlyamong diets. No spider survived until adulthood onthe diet of GLH, only a single male individual sur-vived on a diet of BPH, 70% survived until adult-hood on a collembola diet, and all spiders survivedon the mixed diet. Spiders developed fastest on themixed diet and the collembola diet.

Because no adult females developed on the twohopper diets, it was possible to compare fecunditiesonly on collembola and mixed diets. Of these, thefemales on mixed diet had the highest fecundity.

We concluded that alternative prey not only in-crease the population of predators but are a neces-sity because BPH and GLH alone did not providefood enough to increase the number of predators.

Progress of unreported projects

Increasing water use efficiencyin rice cultureT.P. Tuong, A.M. Mortimer, B.A.M. Bouman,and D.C. Dawe

● Established a database on results of 31 his-toric water-saving irrigation (WSI) experi-ments. The analysis shows that WSI generallysaves water and increases water productivity

(grains produced per unit water used) at thefield scale, but that land productivity (yield)decreases. The crop growth and water balancesimulation model ORYZA was developedfrom former ORYZA1 and ORYZA-W mod-els to support the empirical data analysis ofWSI experiments.

● Started multilocation field monitoring of wa-ter flows within 1) District I of the UpperPampanga River Integrated Irrigation Sys-tem; 2) Sta Cruz irrigation systems in Laguna,Philippines; and 3) Cu Chi irrigation systemin Vietnam to study water (re-use and waterproductivity at different spatial scale levels.

● Started a field water balance study at threespatial scale levels (field, irrigation sub-system, and whole irrigation system) in theZang He irrigation system, China, togetherwith field experiments into cropping underthe ACIAR-SWIM project.

● Conducted a survey of farmers in China toassess the economic profitability of water-saving irrigation (in collaboration with scien-tists from WUHEE).

● Analyzed the impact of large-scale adoptionof direct seeding on water productivity in theMuda irrigation scheme and completed a sur-vey of 200 farm households to analyze theeconomics of alternative crop establishmentmethods.

● Analyzed secondary time-series data on pro-duction, area, and yield for the Philippines.Found that El Niño events (which causedrought in the Philippines) are responsible formost of the important fluctuations in pro-duction at the national level. In relation to theEl Niño drought of 1998, found that mostfarmers were unable to plant alternativecrops, and that the most common copingmechanism was to rely on monetary transfersfrom family and friends who had access tosources of nonfarm income.

● Completed a survey of rice crop establish-ment practices of farmers in Nueva Ecija,Philippines. The results indicate that farmersare likely to establish rice early by seedingonly when irrigation authorities are able toassure water supply when rainfall is insuf-ficient.


● Characterized variation in growth traits ofweedy rice populations in the Philippines.Found that variation in trait combination washighly population (farm)-specific, suggestingstrong inter-population selection.

● Developed and began validation of a simula-tion model DSRICE1 for examining weed-crop competition for direct-seeded rice. Illus-trated the importance of vertical leaf canopydistribution in governing yield determinants.

● Conducted experiments into role of nitrogenin governing root-shoot bioma allocation inweed species and its subsequent effect on riceweed competition and yield.

● Developed methodology for measuring microfield levels in dry and saturated soils and ofmethods to quantify variability of emergencein wet direct-seeded fields.

● Fabricated a ride-on boom sprayer suitablefor small Asian rice fields for improved pes-ticide application and safety.

Coping with global climate change:reducing methane emission from rice fieldsR. Wassmann and R. Lantin

● Comprehensively evaluated, documented,and published data obtained over 6 years ateight stations of the UNDP project.

● Overall, assessed mitigation technologies re-garding their potential for emission reductionand specifics of application.

● Clarified the ultra-structural pathway ofmethane gas through the different plant com-partments.

● Upscaling of emission rates through a processmodel and GIS techniques yielded conclusiveestimates on national source strengths.

Irrigated Rice Research Consortium

Coordination● Provided general coordination of the IRRC:

membership, agenda, resource allocation, etc.● Continued implementation of the nutrient-

pest interaction research.● Supported training workshop (Uttar Pradesh,

India) on database management and a sitevisit (Tamil Nadu, India) for the nutrient-pestinteraction research collaborators.

● Supported participants from the Consortium(networks) to participate in IRRI/Network-conducted training course (SRINM, SWBE,Ethnoscience).

● Conducted the second joint meetings of theIRRC, INMNet, and IPMNet steering com-mittees and the IRRC external review (Hanoi,Vietnam).

Research● Conducted data management workshop for

pest impact assessment (PIA) research colla-borators.

● Conducted pest survey in RTDP farms (PIA)for three seasons at seven IRRC sites (crop 1data had been collated and initially analyzed;crop 2 data had been collated; and most ofcrop 3 data are still with research collabo-rators).

● Conducted crop residue management (CRM)for three seasons (out of 5) of research at foursites (CRM research will be a continuing ac-tivity until the 3rd quarter of 2000).

Program outlook

The Irrigated Rice Ecosystem program will con-tinue research to raise the yield barrier through col-laboration in a systems approach to development ofnew plant types and hybrid rice. High yield-deter-minant growth patterns, new genes for lodging re-sistance, tungro viruses, and stem borer and blastresistance will be the focus, along with improvedgrain-filling capacity in the NPT. Research on high-yielding hybrid rice from CMS and TGMS lineswill continue with advanced breeding materials in-troduced to the national agricultural research sys-tems (NARS).

The program will continue research on soil qual-ity and nutrient management. Research on optimalN applications, internal nutrient efficiencies, andmodeling the nutritional balance will be directedtoward sustainable nutrient management in inten-sively cropped irrigated lowlands. Identificationand quantification of key biotic and soil organic de-terminants of sustainability and ecological resil-ience will also be addressed. Studies on the con-straints to nutrient supply, and the development ofpractical approaches through site-specific nutrientmanagement technologies in partnership with


NARS and farmers are nearing the stage for large-scale technology transfer.

Efforts to improve water use on-farm and in irri-gation districts will focus on land preparation, cul-tivation period, and weed and crop establishment indirect-seeded rice under intermittent irrigation. Re-search on water quality degradation and the devel-opment of feasible mitigation strategies will con-tinue.

Characterization of pest problems and generationof practical pest management strategies will be sus-tained. Adaptation of integrated pest management(IPM) will focus on motivating farmers throughprinted materials and radio. Surrogate taxa analysisof rice invertebrates and assessment of predators’directional movement in irrigated rice are underway.

The IRRC will continue to link with NARS andother institutions to address important inter-disciplinary regional problems. The networks inIRRC will continue to address NARS-driven IPM,integrated nutrient management, and hybrid rice re-search priorities.

Two SDC-supported projects, the IPM Project(within IPMNet) and RTDP Project (withinINMNet), and the ADB-supported Hybrid RiceNetwork (HRNet) have been formally linked in theconsortium. The initial results of the nutrient-pestinteractions research in intensive irrigated rice sys-tems are under analysis and will direct the nextphase of this work.

The IRRC will broaden to include other aspectsof irrigated rice research on water management,farm mechanization, and global climate change.

Research programsRainfed lowland rice ecosystem

CHARACTERIZING AND ANALYZING RAINFED RICE ENVIRONMENTS 26Water-balance modeling to study regional drought risk and crop management strategies (SS, SWS) 26Land use dynamics and changes in rice production in the Mekong River Delta in the 1990s (SS) 29Rice yield and yield stability patterns in eastern India (APPA) 32

Categorizing rice systems according to yield and yield stability 32Production systems within ecosystems 32

ADDRESSING GENDER CONCERNS IN RICE RESEARCH AND TECHNOLOGY DEVELOPMENT 33Eliciting male and female farmers’ perceptions of rice varieties (SS, APPA) 33

Description of the farming systems 34Gender division of labor 35Male and female farmers’ criteria for traits of rice varieties 36Farmer participation in rice varietal selection 37

RAINFED LOWLAND RICE RESEARCH CONSORTIUM 38Climate, agrohydrology, and management of rainfed rice production in Central Java:

a modeling approach (SWS) 38Effect of climate and agrohydrology on rice production 38Management options to increase yield 39

Dynamics, balance, and recycling of residual soil N in a lowland rice-sweet pepper system (SWS) 39Rice yield, N uptake, and N use efficiency 40Nitrogen balance 40

Carbon management for sustainability of an intensive rice-based cropping system (SWS) 41

PROGRESS OF UNREPORTED PROJECTS 43Managing crop, soil, and water resources for enhanced productivity and sustainability of lowland areas 43Germplasm improvement for rainfed lowland rice 44

PROGRAM OUTLOOK 45


Rainfed lowland rice ecosystem

Characterizing and analyzingrainfed rice environments

Research through 1997 developed the methodologyand database for characterizing the biophysical as-pects of the systems at different scales and quanti-fied biotic stresses in rainfed ricefields. Since 1997,research on socioeconomic components has in-creased. Focus has been on integrating various com-ponents of the biophysical components to better de-scribe the complex environment.

Water-balance modeling to study regionaldrought risk and crop managementstrategiesS.P. Kam, T.P. Tuong, B. Bouman, S. Fajardo,and J.P. Reyes

Drought is a main cause of low and unstable riceyields in the Korat Plateau of Thailand. An under-standing of its temporal and spatial occurrence isimportant for identifying strategies for geographicaltargeting of improved varieties. A water-balancemodel that takes into account climatic, soil, and cropfactors was developed to quantify the frequency andseverity of drought at different stages of lowlandrice.

The weekly field-water balance components werecalculated as follows:

Wt = Wt-1 + Pt – ETt – Gt – Rt

where W = field-water storage (mm) (includes wa-ter storage within the root zone and standing wateron the soil surface); P = precipitation (mm wk–1); ET= evapotranspiration (mm wk–1). When the soil isbare, this is replaced by evaporation from bare soil

Rainfed lowland rice is grown on more than 48 millionha, with one-third of that in South and Southeast Asia.In most rainfed lowland areas, rice is often the onlycrop grown. The objectives of the rainfed lowlandprogram are:

● improve the understanding of the biotic andsocioeconomic constraints to increaseproductivity and stability of rice yield;

● develop technology for better management ofsoil, water, and biotic resources to increase riceyield and sustain the natural resource base; and

● improve germplasm to overcome the constraintsimposed by poor soils, drought, andsubmergence.

Rainfed lowland rice ecosystem 27

[ES]; G = percolation (mm wk–1), which occurswhen there is standing water in the field; R = runoff(mm wk–1), which occurs when the depth of stand-ing water (H) in the field is higher than the effectivebund height (Hmax); subscript t signifies the weekunder calculation; and t-1 signifies the previousweek.

Starting with a given field-water storage of theprevious week (Wt-1), the model consecutively cal-culates ETt (or ESt if the soil is bare), Gt, Rt, and Wt.

The water-balance model was run using data ofthree typical soil types ranging from the coarsest(sandy loam) to the finest (clayey loam) soils en-countered in the Korat Plateau. Percolation rates anddetailed measurement of water retention functionsreported by previous investigators were used. Thewater-balance model also took into account the ef-fect of late planting on delayed flowering and har-vest. The week of disappearance of standing waterat the end of the rainy season was determined rela-tive to the flowering week. That and the relationshipbetween yield and number of weeks of water disap-pearance before flowering were used to determine

the relative yield reduction due to late-seasondrought stress.

The model was used for 1) a time-series analysisand 2) a spatial surface analysis by linking with geo-graphic information systems (GIS). The time-seriesanalysis used yearly records of weekly climatic datato model annual variations in weekly field-waterstorage. That analysis was done at eight sites. Fre-quency analysis covered the effect of drought on thetimeliness of transplanting, harvest week, and yieldreduction due to late-season drought stress.

In the spatial-surface analysis, long-term averagerainfall data of 126 stations and average Penmanevapotranspiration data of eight stations were inter-polated to generate gridded surfaces as input into thewater-balance model. The outputs of this analysisincluded 5- × 5-km gridded surfaces of weekly field-water storage, timeliness of transplanting, residualsoil moisture at harvest, and yield reduction due tolate-season drought stress.

Figure 1 illustrates the spatial distribution of thefield-water storage at week 31 for clay loam soil.Similar figures were produced for each week of the

1. Field water storage at week 31, based on average weekly rainfall on clay loam soil. Korat Plateau, Thailand, 1999.

103 mm

297 mm

237 mm

NakhonPhanom

Sakon Nakhon

Loei

Khon Kaen

Roi Et

UbonRatchathani

SurinChok Chai

0

50

100

1 50

200

2 50

300

3 50

1 5 9 13 17 21 25 29 33 37 4 1 45 49

0

50

100

150

200

250

300

350

1 5 9 13 17 21 25 29 33 37 41 45 49

0

1 0 0

2 0 0

3 0 0

4 0 0

1 6 1 1 1 6 2 1 2 6 31 36 4 1 4 6 5 1

-5 0

5 0

15 0

25 0

35 0

1 6 11 1 6 2 1 2 6 3 1 3 6 4 1 4 6 51

0

1 0 0

2 0 0

3 0 0

4 0 0

1 6 1 1 1 6 21 2 6 3 1 3 6 4 1 4 6 51

- 50

50

1 50

2 50

3 50

1 6 1 1 1 6 2 1 2 6 31 3 6 41 4 6 51

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

1 6 1 1 1 6 2 1 2 6 3 1 36 41 4 6 5 1

0

50

100

150

200

250

300

350

1 5 9 13 17 21 25 29 33 37 41 45 4 9

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

1 4 7 1 0 1 3 1 6 1 9 2 2 2 5 2 8 3 1 3 4 3 7 4 0 4 3 4 6 4 9 5 2

Stand ard meteorol ogical week

Field Capacity


year. Field-water storage decreases markedly acrossthe Korat Plateau from the northeast to the south-west. Table 1 shows the frequency at which trans-planting was possible (when there were at least 3consecutive wk of standing water) before week 35(start of September) for three soil types at eight se-lected sites. Sites in the northeastern and easternparts of the plateau had higher frequency of trans-planting than sites in the western part.

Figure 2a shows yield reduction due to late-sea-son drought stress for transplanted rice on clay loam.Figure 2b is the yield reduction for direct-seededrice. Comparison of the two maps suggests threemajor zones, indicated in Figure 3, for which differ-ent crop management strategies may be relevant.

Zone A (east-northeastern belt): Transplantinginduces less yield reduction when compared with

direct seeding. However, because rainfall ceasesrather abruptly at the end of the season, late-matur-ing photoperiod-sensitive varieties (such as KDML105) may encounter drought around anthesis, caus-ing yield reduction. The main strategy here is toavoid late drought by the use of nonphotoperiod-sensitive varieties.

Zone B (lower central part of the plateau): Trans-planting is possible but often occurs later in themonsoon season (between wk 26 and 34) and is nor-mally later than direct seeding. Under optimum cropmanagement, direct seeding would be more advan-tageous.

Zone C (western part): Yield loss in transplantedrice is distinctly higher than dry direct-seeded rice.Drought risk in this zone occurs in the early part ofthe season and midseason. Therefore the more ap-propriate management strategy here is the use ofdirect-seeded, drought-tolerant varieties.

Figure 2c depicts the yield reduction for late-sea-son drought stress on direct-seeded rice for the loamysand soil. Percolation rates used in Figures 2b and2c were similar. The clay loam soil in Figure 2b,however, had higher water retention than the loamysand soil in Figure 2c. The high degree of similaritybetween Figures 2b and 2c shows that percolation,rather than the inherent water retention properties ofthe soil, is the overriding factor that influences field-water storage. This suggests potential for improvingwater storage through management such as soilcompaction to reduce percolation losses.

Table 1. Effect of soil type on possibility of transplantingrice (TPR) before week 35 for eight selected sites in theKorat Plateau, Thailand, 1999.

Years of possible TPR in 12 years (no.)Site

Sandy loam Loamy sand Clay loam

Nakhon Phanom 12 12 12Sakon Nakhon 6 8 12Ubon Ratchathani 8 10 11Surin 3 4 10Roi Et 0 3 10Khon Kaen 1 1 8Loei 0 3 10Chok Chaia 0 0 2

aOnly 8 years of weather data available.

2. Simulated yield reduction due to late-season drought stress of a photoperiod-sensitive rainfed lowland rice variety. Korat Plateau,Thailand, 1999.

% Yield Reduction

a. Transplanting case,clay loam scenario

b. Direct seeding case,clay loam scenario

c. Direct seeding case, loamy sandscenario, with halving of percolation rate

481521324873Not applicable


The accuracy of the output of this study is con-strained by a paucity of data for key soil variables,particularly percolation rates. Nevertheless, the studydemonstrates how a simple water-balance modellinked with GIS can be used for regional droughtanalysis. It has implications for broad-scale geogra-phical targeting of crop management strategies. Theresults provide the basis for selecting target areas forin-depth studies of agrohydrological influence onfield-water balance.

Land use dynamics and changes in riceproduction in the Mekong River Deltain the 1990sC. Edmonds, S.P. Kam, L. Villano, and H.C. Viet10

Biophysical and socioeconomic constraints influ-ence land use decisions and affect the production andincome of rice farmers. Characterizing both types ofconstraints and understanding the relationship bet-ween them are essential to development of tech-nologies and policies to increase rice production andincome.

Research in collaboration with the Institute ofAgricultural Sciences, Vietnam, characterizedchanges in agricultural environment and farm res-ponses to changes that enabled production increasesof about 6.3% y–1 in the Mekong River Delta dur-ing the 1990s.

Farm-level changes in rice output were capturedin farm survey data (1994-97) for 149 farms (eightvillages) in the Mekong River Delta. The villagesrepresent a range of agroecological and productionsituations. GIS data on soil types, flooding, watersalinity levels, and transport routes were used tocharacterize the biophysical environment.

Integration of econometric techniques with dataorganized in GIS offers promise for modeling theeffect of the main constraints to rice production. Weapplied microeconomic modeling to explorerelationships between biophysical and socio-economic characteristics, to derive hypotheses, andto form an estimation equation that can be testedusing available data. Estimates assess the importanceof new technology adoption, changes in inputapplication, increased cropping intensity, and localinfrastructure development in explaining observedproduction increases.

Figure 4 superimposes land use as reported byfarms in each of the eight villages on a 1996 land-use map for the Mekong Delta. The figure highlightsthe benefit of integrating GIS with farm survey data.The map gives a complete characterization of landuse, while information from the survey adds a timedimension and provides detailed data on farm re-sources and activities.

For our model, accessibility to markets and riceplots plays a key role in determining the rice crop-ping intensity likely to be adopted by farms. The GISgenerates accessibility indicators. These are used topredict land use and production decisions. Estimatespredicting the rice cropping intensity of farms weresignificant in each of the 4 years. Greater distancesbetween farms and markets were associated with areduced probability of intensive rice cultivation. Thedistance between the farm plot and homesteads hada negative and statistically significant effect on ricecropping intensity in 1995 and 1997 estimates.

The study estimated other land use, as well as riceproduction and supply functions implied by the ana-lytical model or basic microeconomic theory, whichincluded general cropping intensity, farm croppingpattern, and rice production and farm supply of riceto the market. Together, the estimates provide a clearindication of the factors driving farmland use, pro-duction, and marketing decisions.The availability of saline-free irrigation water tofarms had positive and statistically significant effectson the intensity of land use. The magnitude of the

3. Zonation (A,B,C) for rice crop management strategies tocope with drought stress. Korat Plateau, Thailand, 1999.

Zone C

Zone A

Zone B


4. Land use in the Mekong River Delta in the 1990s. Source of land use map is the Soil Science Department, Can Tho University,Vietnam, and the IAS-IRRI project. IRRI, 1999.


effect of high-quality irrigation was much greaterthan the effects of other variables included in themodel.

The level of rainfall had a mixed effect on crop-ping intensity. In years with normal to above-aver-age rainfall, higher levels of rainfall were associatedwith increased cropping intensity. In 1996, increasedrainfall was associated with significantly reducedcropping intensity. The size of families’ land-holdings relative to their available labor had mixedsigns across models and years, but in general sup-ported the hypothesis that relative scarcity of landin relation to labor led to higher cropping intensity.Other variables such as education, age, or farmingexperience had inconsistent or insignificant effectson land use. The estimates of price elasticity of sup-ply ranged between 0.145 and 0.319 in yearly esti-mates.

The implications of regression model estimatesare made clearer by using them to formulate a simu-lation model to assess the effect of policy changes,or investments in infrastructure, on land use and riceproduction. The results of a model derived from ourempirical estimates are summarized in Tables 2 and3. Table 2 shows the distribution of mono-, double-, and triple-cropped rice among surveyed farms for1994-97 with three alternative infrastructure invest-ment scenarios. The implied changes in the share offarms with double- or triple-cropped rice can be usedto derive an implied increase in aggregate rice out-put using results from production function estimates.The estimated changes in total rice production areseen on Table 3.

The simulation illustrates how the results of landuse and production estimates based on the observedbehavior of farms can be used to assess the likelyeffects of different investments on rice productionlevels. In this case, it shows the large effect of in-vestments in irrigation, and a more moderate effectof improvements in the transportation system, on riceproduction. The integration of behavioral parametersfrom econometric estimates is broadly applicableand can provide an empirical foundation to largersimulation models. Because this study relied on ex-isting data, we encountered severe data constraints.However, the research provided insight into thefarm-level changes in land use and production sys-tems that enabled the rice production increases in theMekong River Delta in the 1990s.

Tabl

e 2

. Sim

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ion

of e

ffec

ts o

f inf

rast

ruct

ure

inve

stm

ents

on

dist

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tion

of f

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ity

in t

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ekon

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iver

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ta, V

ietn

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IRR

I, 1

99

9.

Actu

alPr

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utio

na :Pr

edic

ted

dist

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iona:

Ric

e cr

oppi

ngdi

strib

utio

nale

ss t

han

10 m

in t

rave

lho

me

to p

lot

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ced

10%

bet

ter

wat

er m

anag

emen

tsy

stem

to m

arke

tby

1 k

m

19

94

1995

1996

1997

1994

1995

1996

1997

1994

1995

19

96

1997

1994

1995

1996

1997

Mon

ocro

p3

733

31

12

36

21

26

12

40

29

33

12

15

13

0

12

Dou

ble

crop

ped

7

55

51

45

7

62

51

45

6

57

51

44

8

67

52

38

Trip

le c

ropp

ed1

626

32

20

17

31

37

20

14

28

30

21

37

34

62

27

a Fa

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(no.

)


Rice yield and yield stability patternsin eastern IndiaV.P. Singh and A.S.R.A.S. Sastri24

Quantification of yield, yield stability, and their re-lationship to environmental parameters is beneficialto identifying strategies for sustainable rice produc-tion. The districtwise yearly average rice databasesfrom 1970-71 to 1994-95 were used to calculate theyield coefficient of variation (CV) and do a time-trend analysis of the yield for all of Bihar, Orissa,West Bengal, and eastern parts of Uttar Pradesh andMadhya Pradesh.

CATEGORIZING RICE SYSTEMS ACCORDING

TO YIELD AND YIELD STABILITY

Yields and CV values in each state vary consi-derably. Therefore, criteria were developed (Table4) for categorizing the rice production systems basedon yield and its variability. From those, rice produc-tion can be categorized in four groups (Table 5). Thespatial distribution of the four groups in Bihar ispresented in Figure 5.

The overall analysis of eastern India shows thatamong 93 districts, 54 have a low and unstable sys-tem of rice production, 16 have a low and stablesystem, 22 have a high and unstable system, and onlyone has a high and stable system.

PRODUCTION SYSTEMS WITHIN ECOSYSTEMS

District rice area under different categories of pro-duction systems was classified under different riceecosystems (Table 6). Almost 16 million ha of riceare in the low and unstable category, of which 26.1%is in the upland ecosystem, 45.3% is in the rainfedlowland ecosystem, 12% is in the deepwater ecosys-tem, and the remaining 16.6% is in the irrigated sys-tem.

About 2.7 million ha of rice area are in the lowand stable category of production system. This en-tire area has a good potential for increasing rice yield.Likewise, about 5.7 million ha are in the high andunstable category, which would need intervention tostabilize yields.

Long-term strategies would be required for im-proving rice production in the low and unstable pro-duction system. The logical approach would be in

Tabl

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. S

imul

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effec

ts o

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19

94

1995

1996

1997

1994

1995

1996

1997

1994

1995

1996

1997

1994

1995

1996

1997

Mon

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11

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26

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23

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17

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51

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44

85

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44

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steps—increase some yield and stabilize it at thatlevel before taking the next step of increasing yield,and so on.

The stepwise approach would not require largeexpenditure on inputs at once and the yield stabili-zation period would provide options for building theresource base to some extent. That can then be usedfor increasing the yield to the next level.

Addressing gender concerns in riceresearch and technology development

Research in this project aims to incorporate wom-en’s knowledge and concerns in identifying andadapting mechanical postharvest technologies thatadd value to rice and byproducts. It also examinesmethodologies for incorporating male and femalefarmers’ knowledge of traditional cultivars and theircriteria for varietal selection into plant breeding strat-egies. IRRI participates in the CGIAR systemwideinitiative on Participatory Research and GenderAnalysis for Technology Development and Institu-tional Innovation.

Table 4. Rice yield and variability classification for eastern India. 1999.

Yield Variability

(t ha-1) Code Classification CV (%) Code Classification

<0.8 1 Extremely low <10.0 6 Very stable

0.81 to 1.0 2 Very low 10.1- 15.0 5 Stable1.01 to 1.20 3 Low 15. -20.0 4 Moderately stable

1.21 to 1.40 4 Moderately high 20.1-25.0 3 Moderately unstable

1.41 to 1.60 5 Fairly high 25.1-30.0 2 Unstable>1.60 6 High >30.0 1 Very unstable

Table 5. Rice production system classification in easternIndia. 1999.

Combination of the codes ofCategory of rice

Yield Variability production system

1, 2, & 3 1, 2, & 3 Low and unstable

1, 2, & 3 4, 5, & 6 Low and stable4, 5, & 6 1, 2, & 3 High and unstable

4, 5, & 6 4, 5, & 6 High and stable

Eliciting male and female farmers’perceptions of rice varietiesT R. Paris, A. Singh,11 M. Hossain, J. Luis,H.N. Singh,11 O.N. Singh,11 S. Singh,11

and R.K. Singh

Encouraging women farmers to participate in theprocess of germplasm enhancement and conserva-tion is important for achieving positive impact onrice farming families in rainfed environments.

Farmer participatory plant breeding (PPB) forrainfed rice was developed at IRRI in 1997 in col-laboration with national agricultural research sys-tems (NARS) in eastern India. The aims were to testthe hypothesis that farmer participation for rainfedrice breeding can help develop suitable varietiesmore efficiently. The research has two components:

● a plant breeding component, which aims todevelop and evaluate a methodology forscreening improved germplasm for hetero-geneous environments through farmer partici-pation; and

● a social science component, which aims toestablish a farmers’ typology to guideestablishment of breeding goals that suit theneeds of various groups.

In 1998, we began to incorporate gender concernsin the ongoing PPB project. The strategies were

● Develop methodologies for assessing maleand female farmers’ criteria of useful traits ofrice varieties.

● Develop participatory approaches that includemale and female farmers in selecting new ricelines.


WestSinghbhum

Gumla

Ranchi

DaltenganjHazaribag

Giridih

Dhanbad

Deoghar Dumka

Rohtas

GayaAurangabad

Nawada

Munger

Bhagalpur Godda

Sahibganj

Patna

Nalanda

Bhojpur

Saran

VaishaliSamastipur

Katihar

Purnia

Begusarai

Darbhanga

Saharsa

Madhubani

MuzaffarpurSiwan

GopalganjE. Champaran

W. Champaran

Sitamarhi

Low and unstable

Low and stable

High and unstable

High and stable

Data not available

Madhepura

Jehanabad

EastSinghbhum

5. Rice production systems in Bihar District, India. 1999.

● Enhance women’s knowledge and skills ingermplasm conservation.

● Enhance NARS capacities for conductingmale and female farmer participatory ap-proaches in rice germplasm enhancement andconservation in rainfed rice environments.

DESCRIPTION OF THE FARMING SYSTEMS

We initiated the gender study in Mungeshpur inFaizabad District and Basalatpur in SiddathnagarDistrict, eastern Uttar Pradesh. PPB research hadincluded the same villages. Basalatpur representsfavorable lowland rainfed areas and Mungeshpur


Table 6. Area under various rice production systems and ecosystems in eastern India. 1999.

Rice area ('000 ha)Rice productionsystem and Eastern Easternecosystem Bihar Orissa Uttar Madhya West Total

Pradesh Pradesh Bengal

Low and unstableUpland 531 691 714 1,349 883 4,168Rainfed lowland 1,142 1,667 1,723 2,695 – 7,227Irrigated 552 844 648 608 – 2,652Deepwater 807 495 606 – – 1,908Total 3,032 3697 3,691 4,652 883 15955

Low and stableRainfed lowland 762 437 – – 563 1,762Irrigated 100 41 – – 260 401Deepwater 187 55 – – 268 510Total 1,049 533 – – 1,091 2,673

High and unstableRainfed lowland 248 125 451 – 1,592 2,416Irrigated 660 177 334 – 1,064 2,235Deepwater 30 – 183 – 792 1,005Total 938 302 968 – 3,448 5,656

High and stableRainfed lowland 11 – – – – 11Irrigated 200 – – – – 200Deepwater 30 – – – – 30Total 241 – – – – 241

TotalUpland 531 691 714 1,349 883 4168Rainfed lowland 2,163 2,229 2,174 2,695 2,155 11416Irrigated 1,512 1,062 982 608 1,324 5,488Deepwater 1,054 550 789 – 1 060 3,453Total 5,260 4,532 4,659 4,651 5,422 24525

represents shallow and submergence-prone areasthat are favorably rainfed during years of low rain-fall. Although modern varieties are grown inMungeshpur, they are not suitable for cultivation asrainfed lowland rice and often suffer from submer-gence and drought and stress at the reproductive andripening phases when the crop is planted late.

Farmers in Mungeshpur have more access to sup-plementary irrigation than farmers in Basalatpur,which enables farmers to grow vegetables and toincrease crop diversification during the winter sea-son (Nov-Dec to Mar-Apr). Most farm householdsin Mungeshpur belong to the lower caste (backwardand scheduled), while Muslims dominate the popu-lation in Basalatpur. The Yadavs, a subcaste of thecaste in Mungeshpur, take care of milch animals.

Degree of market orientation is high inBasalatpur, which is near a city. Rice grown in

Mungeshpur is mainly used for home consumption.Rice/wheat mixed with mustard is the dominantcropping pattern in both villages, occupying morethan half the cultivated area.

GENDER DIVISION OF LABOR

The extent of female participation in rice productionis high in both villages. Land preparation and appli-cation of chemicals are mostly men’s responsibili-ties.

In Mungeshpur, women from the lower socialstatus dominate in pulling of seedlings (100%),transplanting (70%), weeding (80%), application offarmyard manure (60%), harvesting (82%), andthreshing (82%). In Basalatpur, men and womenequally share in the pulling of seedlings and har-vesting. Women do the transplanting of seedlings


(100%), and most of the weeding (75%) with mendoing most of the spraying (90%). Basalatpur farmsare mechanized, using tractors for land preparationand threshing, but in Mungeshpur bullocks are usedfor land preparation and threshing is done by hand.Livestock is more important in Mungeshpur than inBasalatpur. Postharvest activities such as seed selec-tion, storage, manual dehulling, hand threshing, par-boiling rice, and making rice puffs are major respon-sibilities of the women of small farming households.Aside from their significant contributions in cropproduction, they take care of dairy cattle, collectgreen animal fodder, and feed and tend livestock.

MALE AND FEMALE FARMERS’ CRITERIA

FOR TRAITS OF RICE VARIETIES

We interviewed 15 males and 15 females from sepa-rate households and different social groups inMungeshpur and Basalatpur. Each farmer was askedwhat traits he, or she, considered in selecting ricevarieties for each major land type in their fields. Weasked: “If you had 100 paisa, how much would you

Table 7. Traits farmers mentioned as useful when selecting rice varieties in Basalatpur and Mungeshpur, eastern UttarPradesh, India, 1999.

Basalatpur Mungeshpur

Upland Lowland Upland LowlandTraita

Male Female Male Female Male Female Male Female(%) (%) (%) (%) (%) (%) (%) (%)

Grain yield 36.8 39.5 48.7 49.7 41.6 36.0 42.1 40.4Duration 25.9 34.5 0.7 1.0 20.5 25.9 20.6 15.0Grain price 0.0 0.0 15.6 16.0 1.7 2.8 3.0 1.8Resistance to abiotic stress 8.4 6.5 0.8 0.5 5.6 6.2 5.1 5.0Biomass quality 3.3 2.5 5.3 5.7 5.0 2.3 5.4 8.6Taste 1.7 0.5 10.3 12.3 2.8 2.8 2.1 3.2Bold and pure grain 7.7 1.5 1.7 0.0 4.4 4.4 3.4 5.0Adaptation to specific soil type 3.0 3.0 2.3 0.7 5.0 4.4 5.4 6.4Postharvest quality 0.8 3.0 6.7 7.8 0.0 5.1 0.0 2.3Resistance to biotic stress 4.2 2.5 1.0 1.3 3.9 1.7 4.3 3.2Cooking characteristics 0.8 1.0 1.7 2.0 3.9 3.9 3.4 5Response to fertilizer 2.5 1.0 2.7 1.3 5.0 2.3 4.3 1.8Competitiveness with weeds 0.0 0.0 0.0 1.0 0.0 2.2 0.0 2.3Resistance to lodging 1.7 0.0 2.3 0.7 0.0 0.0 0.9 0.0Early vegetative vigor 0.9 0.5 0.3 0.0 0.6 0.0 0.0 0.0Culm strength/diameter 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0Adaptation to several preparations 1.8 3.5 0.0 0.0 0.0 0.0 0.0 0.0

aGrain yield includes tillering, panicle length, and number of grain; resistance to biotic stress includes resistance to pests, bugs, and blast;resistance to abiotic stress includes resistance to Zn deficiency and drought; biomass quality includes height, quality, and quantity of straw;postharvest quality includes easiness to dehull and milling recovery; and cooking characteristics include cooking time, elongation ability,aspect after cooking, and impression in the stomach.

pay for each trait?” to obtain the weight or impor-tance given by farmers to a particular trait. Wesummed the weights per trait of all respondents ineach land type and took the proportion of each traitto all traits mentioned. Table 7 shows the selectioncriteria of male and female farmers for different landtypes and villages.

Male and female farmers in Basalatpur agreedthat grain yield, grain price, and taste are the mostimportant traits they consider in choosing rice vari-eties. Grain price is an important consideration forcommercial farmers. Many produce the traditionalvariety, Kalanamak, as it commands a higher pricebecause of good taste and aroma even though ityields 1.5–2 t ha –1. In contrast, grain price is not animportant consideration in Mungeshpur because riceis mainly used for home consumption.

Male and female farmers in Mungeshpur citedgrain yield and duration (125–135 d) as the mostimportant traits they consider in growing rice.Women, but not men, mentioned competitivenesswith weeds and postharvest quality as importanttraits in selecting rice varieties. Weeds are the ma-


jor problem in the uplands, particularly when rice isdirect seeded. In the lowlands, weeds are moreprevalent during drought. Gender-specific tasks in-fluenced choice of variety. Tradeoffs among the dif-ferent traits in variety selection between men andwomen representing different socioeconomic groupswill be studied in 2000.

FARMER PARTICIPATION IN RICE VARIETAL

SELECTION

Two farmers from each of the villages ofMungeshpur and Sariyawan (rainfed neighboringvillage) and Basalatpur were selected to check theperformance of 13 rice cultivars on their fields dur-ing the 1998 monsoon season. Included were 10advanced lines and three released varieties for low-lands. Two were scented varieties: Kamini, whichflowers in 136 d, and Sugandha, which flowers in124 d. Seed was distributed through the PPB projectand breeders selected the most promising lines withfarmers’ input. Female farmers were included to givethem an equal chance to participate in decisions inselecting rice genotypes. Ten farmers (five femalesand five males) visited individual plots on farmers’fields and ranked the genotypes at maturity. Farm-ers were asked to rank the lines from 1 (excellent)

to 13 (worst) on the basis of visual assessment. Thefarmer rankings generated an n × k matrix, where nare the lines being evaluated and k are the farmersevaluating the crop performance. Kendall’s coeffi-cient of concordance (W) was used to measure theagreement in rankings among male farmers and fe-male farmers, and the correlation between male andfemale farmers’ ranking. High and significant cor-relation values indicate close agreement on the rank-ing of the 13 rice genotypes by men and women inthe sample.

Table 8 shows that male and female evaluatorsin the two villages were in close agreement in theranking of the 13 lines. The Ws were highly signi-ficant, revealing that farmers’ ranking is acceptable.In Mungeshpur, NDR973004 was ranked highest byboth males and females because it matures early andyields better than the local check (Mashuri). BothNDR973003 and NDR9730012 are resistant todrought. In Basalatpur, both male and female farm-ers rated Kamini as the best variety because of itshigher yields (3–3.5 t ha–1) and early maturity com-pared with Kalanamak, which matures in 160–165d.

The initial findings indicate that although womenhave less access to education and extension services,they are as knowledgeable as men in identifying the

Table 8. Average scores and farmers’ rankings of 13 rice genotypes in on-farm plots at Basalatpur and Mungeshpur,Uttar Pradesh, India, 1999.

Basalatpur Mungeshpur

Genotypea Males Females Males Females

Av score Rankb Av score Rank Av score Rank Av score Rank

NDR-40032 3.6 2 3.8 3 5.2 5 4.8 5Kamini-KMJ-1-17-2 2.0 1 1.4 1 8.0 7 3.8 3NDR-973004 5.4 5 4.0 4 1.2 1 1.4 1NDR-95003 7.0 7 7.4 8 3.4 3 4.2 4Satyam-Sugandha 5.8 6 6.8 7 11.2 11 12.6 13NDR-973000 7.0 8 6.6 6 8.6 9 12.0 12NDR-9730015 3.6 3 3.3 2 8.4 8 10.8 11NDR-9730020 8.2 9 9.0 10 9.6 10 9.4 9Malasia-Mashuri 11.0 11 11.2 11 5.6 6 7.0 7RAU-136- RAU-1306 11.6 12 11.6 12 4.6 4 6.0 6NDR-9730012 4.2 4 4.2 5 1.8 2 1.6 2RAU-1326 13.0 13 13.0 13 11.8 13 7.4 8NDR-9730025 8.6 10 8.8 9 11.6 12 10.0 10

Kendall’s Wc 0.75* 0.85* 0.87* 0.88*

aWhere genotypes differ, the first given is that used in Basalatpur, the second is that used in Mungeshpur. bRankings from 1 (excellent) to 13(worst) on basis of visual assessment. cKendall’s coefficient of concordance (W); * = significant at P = 0.01


useful traits in rice. If given proper guidance, tech-nical knowledge, and access to new seeds suited totheir environment and needs, women can contributestrongly to faster adoption of improved rice varie-ties. We will continue to validate these findings atother sites and further develop methodologies forinvolving women in variety selection and sensoryevaluation.

Rainfed Lowland Rice ResearchConsortium

The Rainfed Lowland Rice Research Consortium(RLRRC) implements research in rainfed lowlandenvironments in Bangladesh, India, Indonesia, Phil-ippines, and Thailand. Each site represents asubecosystem for research focus.

Climate, agrohydrology, and managementof rainfed rice production in Central Java:a modeling approachA. Boling, T.P. Tuong, B.A.M. Bouman,M.V.R. Murty, and S.Y. Jatmiko4

The typical rainfed cropping system in Central Javaincludes dry-seeded rice (DSR) grown from Novem-ber to February (gogorancah), followed by a trans-planted rice (TPR) from March to June (walikjerami). Earlier studies showed that the yield of thewalik jerami crop was lower and less stable than thatof the gogorancah crop.

We collaborated with the Central Research Insti-tute for Food Crops, Indonesia, to assess the climaticand agrohydrologic constraints to rice productionand explore management strategies to increase theyield and yield stability of the double rice croppingsystem in Central Java. The crop growth simulationmodel ORYZA was used.

The ORYZA model was validated with data from1995-96 field experiments at Jakenan. Long-termsimulation of the potential and rainfed rice yield wasdone for IR64 grown on a 15-d planting interval for1977-98. Three water table depth scenarios (me-dium, shallow, and deep), corresponding to themean, mean + standard error, and mean – standarderror of measurements in six rice cropping seasonswere used in the simulation. A series of simulationruns explored the effect on yield of supplementaryirrigation and of varieties with duration shorter thanIR64.

O N D J F M A M J J A S O

12

10

8

6

4

2

0

O N D J F M A M J J A S O

Dryseeded Transplanted Dry

seeded

Day of seeding

Simulated yield (t ha-1)

Rainfed, shallow water tableRainfed, medium water tableRainfed, deep water tablePotential

6. Simulated potential and rainfed rice yield (mean±SE)in Jakenan, Central Java, Indonesia. IRRI, 1999.

EFFECT OF CLIMATE AND AGROHYDROLOGY

ON RICE PRODUCTION

Potential yield. The simulated, long-term averagepotential rice yield ranged from 6 to 8 t ha–1 (Fig.6). The standard errors of the average values are low,indicating little variation in potential yields acrossyears. Rice sown in the typical walik jerami periodhad a higher yield potential than rice planted in thetypical gogorancah period. Radiation and tem-perature regime are thus not the determinant factorsfor the reportedly low and unstable yield of the walikjerami rice.

Rainfed yield. Figure 6 shows that the yield of ricesown from mid-November to the end of March dif-fered significantly among the three water tabledepths. Rice yields reached the potential yield levelwith the shallow water table, but yields were muchreduced in the other two water table depths. Forcrops sown at the end of the wet season (WS) andin the dry season (DS) (roughly April-November),the yield was low and yield differences among thewater table scenarios diminished. The low yields inthis season were attributed to a deep water table(>1.2 m) and to inadequate rainfall.

The results highlight the important effect of thegroundwater depths on rice yield. More research isneeded to better quantify groundwater depth.


MANAGEMENT OPTIONS TO INCREASE YIELD

Establishment date. Figure 6 shows that the yield ofrainfed rice started to decline at different seedingdates in the three water table scenarios. The yielddecline was attributed to drought stress during thereproductive stage of the crops.

The results indicate that timely planting is criti-cal to sustain yield of the walik jerami crop. Cut-offdates could be determined for transplanting of walikjerami. Beyond those dates, the farmer could chooseto forgo the walik jerami crop or plant it and risk lowyield.

Supplementary irrigation. Yield increase in irri-gation scenarios is seen in Figure 7. Irrigation when-ever the topsoil fell below field capacity (scenarioI1) increased the yields of crops sown in a typicalwalik jerami period (Feb–Mar) by 2.1–3.2 t ha–1

when compared with yields as nonirrigated rainfedrice. A daily irrigation of 7.5 mm water from pani-cle initiation to maturity of the crop (scenario I2)increased the yield by 1.5–3.1 t ha–1, and a daily ir-rigation of 3.3 mm water from panicle initiation tomaturity (scenario I3) increased the yield by 0.5–1.2 t ha–1.

The maximum yield increases for every m3 ofirrigation water applied in the three scenarios oc-curred for crops sown in early March. Water storedin on-farm reservoirs (now widespread in CentralJava) can thus be used effectively to increase yieldand yield stability of walik jerami crop. The simu-lation study may supply necessary information for

7. Yield increase in three irrigation scenarios for rice plantedfrom February to April in Jakenan. Irrigation scenarios includeirrigation when moisture of the topsoil falls below field capacity(0.34 cm3 cm–3, I

1); and when irrigated daily with 7.5 mm (I

2)

and 3.3 mm (I3) from panicle initiation to maturity. IRRI, 1999.

8. Combined yield of gogorancah and walik jerami rice cropsusing IR64 (V

1) and a variety with a 10-d reduction in duration

(V3) with three seeding dates. IRRI, 1999.

the required capacity of the reservoirs as well as forthe cost-benefit of using the reservoirs for supple-mentary irrigation.

Short-duration rice variety. The combined yieldof the gogorancah and walik jerami crops for IR64(V1) and for a hypothetical variety (V3) with 10-dreduction in growth duration as function of sowingdate of the gogorancah crop is shown in Figure 8.In these simulations, a 10-d turnaround time betweenthe harvest of the gogorancah and the transplantingof the walik jerami crop was used. The combinedyield of variety V3 sown on 15 Nov was lower thanthat of IR64, but the combined yield when thegogorancah was sown in December was higher thanthat of IR64 at all probability levels. Early planting(and hence early harvest) of gogorancah did not ex-pose the succeeding walik jerami to late-seasondroughts and switching to shorter duration varietiesreduced the combined yield because the potentialyield was reduced with shorter duration. In the yearswith late arrival of rainfall, growing a short-durationvariety in the gogorancah season advanced the trans-planting of the walik jerami crop and helped it es-cape the late-season droughts. In such years, plant-ing varieties with shorter duration may help increaseyield and yield stability.

Dynamics, balance, and recycling of residualsoil N in a lowland rice-sweet pepper systemJ.K. Ladha, R.K. Shrestha, and S.R. Pascua25

Lowlands in Ilocos Norte, Philippines, have a sys-tem of WS rice followed by one or two nonrice, high-value DS crops (sweet pepper, tomato, garlic,

Day of seeding

J F M A M

I1: 0.34 cm3 cm-3

I2: PI to M, 7.5 mm d-1

I3: PI to M, 3.3 mm d-1

Yield increase (kg ha-1 m-3 irrigation)

1.0

0.8

0.6

0.4

0.2

0.0

I1: 0.34 cm3 cm–3

I2: PI to M, 7.5 mm d–1

I3: PI to M, 3.3 mm d–1

Probability of exceedance

0.00 0.20 0.40 0.60 0.80 1.00

16

12

8

4

0

Yield (t ha-1)

Nov 15 V1 Nov 15 V3Dec 01 V1 Dec 01 V3Dec 15 V1 Dec 15 V3


mungbean, maize, and tobacco). Farmers usuallyapply high rates of N fertilizer to the DS crops, re-sulting in N losses ranging from 34 to 549 kgha–1. The largest N loss is in rice-sweet pepper, apredominant cropping sequence. The reasons for theexcessive use of N fertilizer are not known, but higheconomic returns discourage farmers from beingconcerned about sustainability. The N not used bythe crop is prone to loss through leaching or deni-trification or both, which results in a net reductionof the mineral N pool at the beginning of the ricecrop.

A fallow period during the dry-to-wet season(DTW) transition provides an opportunity to growa crop to capture NO3–-N and recycle it through resi-due incorporation. Experiments with rice-sweet pep-per in farmers’ fields at four sites aimed to1) quantify the amounts of N released from theresidues of different transition crops and their effectson rice yields and N use efficiency, and 2) estimatethe soil mineral N balance.

Nitrate catch crops were grown during the DTWtransition period. At site 1, the DTW transition treat-ments differed in the species of transition cropsgrown—indigo, indigo+mungbean, and maize inaddition to fallow (farmer practice). Transition cropresidues equivalent to 87 kg N ha–1, after deter-mining the N content of all transition crops on theday of harvest, were returned to the soil during WS.Nitrogen fertilizer (87 kg N ha–1) for rice, if applied,was prilled urea (PU) or tablet urea (TU). At othersites, the DTW transition treatments included fallowand indigo, and WS treatments included no fertilizerN, fertilizer N, and residue N equivalent to 87 kg Nha–1.

RICE YIELD, N UPTAKE, AND N USE EFFICIENCY

Rice grain yield ranged from 3.1 to 6.6 t ha–1 acrosssites and treatments, with a corresponding N uptakeof 48 to 146 kg ha–1 (Table 9). Grain yield and Nuptake were significantly different with residue vswithout residue, and with PU vs TU. But both pa-rameters did not differ among residues.

At site 1, yield with TU was about 1.2 t ha–1

higher than with the equivalent amount of PU. Yieldswere similar with the integrated use of indigo ormungbean, or both, with mineral N. At site 2, riceyield and N uptake were similar in the control and

residue treatments because of high residual soil min-eral N. At site 3, yield and N uptake with residuewere lower than with PU for an unknown reason.The increase in grain yield from catch-crop residueN ranged from 39% to 90% of fallow, which wasequivalent to, or higher than, the equivalent amountof N (87 kg PU N ha–1).

Although NH4+-N release was highest with resi-

due or residue with PU, N uptake was highest withfertilizer N, especially with TU. However, grainyields with residue alone or in combination with ei-ther PU or TU were similar to those with fertilizerN but significantly higher than those with the con-trol (zero N). The results indicate a better synchronyof N release and crop demand when a slow-releasefertilizer such as TU or residue plus urea is used.

NITROGEN BALANCE

An apparent mineral N balance was calculated toevaluate the effect of DTW transition and WS man-agement on reducing N loss (Table 10). At site 1,the N loss from the 100-cm soil profile ranged from208 to 516 kg ha–1. It was highest in fallow and low-est in the plot with maize grown during the DTWtransition and its residue incorporated. The effi-ciency of DTW transition crops in decreasing N losswas in the order of maize > indigo+mungbean > in-digo. Maize was highly efficient due to its ability tocapture a larger amount of soil N (177 kg ha–1) thanindigo (151 kg ha–1) and indigo plus mungbean (118kg ha–1). At sites 2 and 3, losses were similar to thosefor site 1. At site 4, the loss in the indigo plot wasnegligible.

The reduction in N loss due to integration of acatch crop during DTW and its incorporation for riceranged from 33% to 72% of the N lost in the fallow.The inability of the transition crop to reduce N lossat sites 1, 2, and 3, as compared with site 4, was dueto the high buildup of soil mineral N (range from 494to 908 kg ha–1 with 97% as NO3–-N), which wasbeyond the capacity of the transition crop to capture.At site 4, indigo was able to reduce N loss by 72%due to lower soil mineral N (260-313 kg ha–1).

Residual mineral N was 2–3 times higher thanthe uptake by the transition crop at sites 1, 2, and 3.That resulted in as much as 83% loss of residual N.This indicates that the strategy of use of a N transi-tion crop alone is not effective enough to reduce sig-


Table 9. Effect of dry-to-wet season (DTW) transition crops on grain yield, N up-take, and agronomic N use efficiency of rice in Ilocos Norte, Philippines. IRRI,1999.

Treatment Agronomic NGrain yield N uptakeb use efficiency

DTW transition Wet seasona (t ha–1) (kg ha–1) (kg grain kgN–1 applied)

Site 1Fallow 0 N 3.1 48 -Fallow PU 4.9 87 22Fallow TU 6.1 101 35Indigo IR 5.4 79 27Indigo IR+PU 5.7 74 31Indigo IR+TU 5.4 78 27Indigo + mungo IMR 4.7 72 19Indigo + mungo IMR+PU 5.2 80 25Indigo + mungo IMR+TU 5.8 83 32Maize MR 4.3 68 14Maize MR+PU 4.9 71 22Maize MR+TU 5.1 73 24

F test ** ** **LSD (5%) 1.0 13 12

Site 2Fallow 0 N 5.9 106 -Indigo IR 6.6 146 8

F-test Ns **LSD (5%) 18Site 3

Fallow 0 N 3.3 48 -Fallow PU 5.3 94 23Indigo IR 4.3 64 11

F-test * ** nsLSD (5%) .69 10

Site 4Fallow 0 N 3.9 53 -

2 Fallow PU 5.4 89 173 Indigo IR 4.9 62 12

F-test ** ** nsLSD (5%) .612 15

a0 N= no applied N, PU = prilled urea, TU = tablet urea, IR = indigo residue, IMR = indigo +mungo residue, MR = maize residue. b Aboveground N uptake including BNF-N.

nificant N loss. There is an urgent need to exploreother avenues such as optimizing N applications toDS crops.

Carbon management for sustainabilityof an intensive rice-based cropping systemJ.K. Ladha and R.K. Shrestha

The sustainability of agroecosystems depends onmaintaining the reserve of soil organic matter(SOM). The release of nutrients from SOM is largelythrough microbial activity, so a supply of readilyusable C is essential to maintain nutrient release. Itis important to differentiate SOM pools into labile(active) and nonlabile (stable) pools because they

play different roles in regulating C and nutrient flowsof soil and in maintaining all aspects of soil fertil-ity. A procedure based on the degree of oxidationof organic C by KMnO4 was used to fractionate la-bile C. That technique allows monitoring the impactof different cropping systems on the change inlability of SOM and hence a measure ofsustainability of the system.

Experiments in four rice-sweet pepper fields inBatac, Magnuang, Ilocos Norte, Philippines, aimedto

● examine the effects of the integration of dif-ferent NO3 catch crops grown during the DTWtransition,


Table 10. Apparent mineral N balance (kg ha–1) from the 0–100 cm soil depth insweet pepper transition crops for a rice cropping system in Ilocos Norte, Philip-pines. IRRI, 1999.

KCl-extractable Soil N ApparentTreatment soil mineral N uptaked loss of soil

(kg ha–1) (kg ha–1) mineral N(kg ha–1)

DTW Wet Maximumb Minimumc Transition Rice (A-B-C-D)transition seasona (A) (B) crope (D)

(C)

Site 1Fallow 0 N 602 43 – 43 516Fallow PU 602 44 – 78 480Fallow TU 602 55 – 91 456Indigo IR 604 51 151 71 338Indigo IR+PU 604 51 151 66 343Indigo IR+TU 604 53 151 70 337Indigo + IMR 539 40 118 65 318mungoIndigo + IMR+PU 539 55 118 72 303mungoIndigo + IMR+TU 539 50 118 74 299mungoMaize MR 494 49 177 61 208Maize MR+PU 494 43 177 64 211Maize MR+TU 494 43 177 66 209

Site 2Fallow 0 N 908 216 – 95 597Indigo IR 744 156 205 131 252

Site 3Fallow 0 N 506 43 – 38 425Fallow PU 506 76 – 80 350Indigo IR 514 54 126 57 277

Site 4Fallow 0 N 313 58 – 47 208Fallow PU 313 78 – 80 155Indigo IR 260 46 131 58 25

a0 N = zero N; PU = prilled urea; TU = tablet urea; IR = indigo residue; IMR = indigo + mungoresidue; MR = maize residue. bMaximum KCl extractable mineral N in most of the transitioncrop was at 29 May, whereas in fallow it was at 23 Jun. About 97% of mineral N was NO

3-N.

cMinimum KCl extractable mineral N in most of the treatment was observed at 30 Sep samplingbut some on 30 Oct. About 90% of mineral N was NO

3-N. dSoil N uptake = aboveground N

uptake-BNF-N. eTransition crops were not planted in fallow plot during DTW transition period.

● examine the effect of incorporation of cropresidues on total C (CT) and labile soil C (CL)pools, and

● determine whether the CL pool and the Cmanagement index (CMI) are suitable para-meters to explain the C status of a soil.

All transition treatments (either fallow or used togrow indigo, an indigo/mungbean intercrop, ormaize) followed a DS sweet pepper crop and WS ricecrop. Residues were returned to the soil. Nitrogenfertilizer for rice was either not applied (0), appliedas PU, or applied as TU.

CT measured by combustion and the amount ofoxidizing agent (KMnO4) consumed were used to

calculate two fractions of organic C—labile C = Coxidized by 333 mM KMnO4 and nonlabile C (CNL)= the remainder. After determining the concentra-tion of CL in the soil, a CMI was calculated.

Across all sites and residue treatments, the CLdecreased (9%) with cropping and increased (47%)with residue incorporation, but CT remained un-changed (Fig. 9). An apparent balance of the CL pool(difference between initial and final) in the sweetpepper-rice system showed the highest positive bal-ance (2.5–3 t ha–1) when an indigo catch crop wasgrown and incorporated, either alone or in relay withmungbean, during DTW transition at site 1 (Table11). Fallow during the DTW transition resulted in a


Catch crop management in an intensive systemcan play a role in maintaining soil health, as indi-cated by improvement in CL. Labile C is sensitiveto soil management practices and provides a bettermeasurement of C dynamics in the short- to medium-term than CT alone, and CMI provides an expressionof C pools or changes in C pools.


Managing crop, soil, and water resourcesfor enhanced productivity and sustainabilityof lowland areas

● Completed special issue of Field CropsResearch, featuring two manuscripts derivedfrom the nutrient + water (N+W) research: onecharacterizing site conditions and the otherexamining nutrient requirements of rice inrainfed lowlands. Over 78 locations, yieldobtained without applied fertilizer were notclosely related to soil test values. The greatestnutrient response was to N, with NPK increas-ing yields from 2.25 to 4.00 t ha-1 on average.The effect of adding micronutrients was smalland PK was of little benefit unless N wasadded. But the magnitude of the N responsevaried substantially with the water regime.Substantial yield grains were possible inrainfed systems by application of appropriatenutrients, especially if used in conjunctionwith cultivars suitably adapted to the targetenvironments.

● Continued studies into selective effects ofwater depth in determining germination andsurvivorship of selected weed species.Continued long-term monitoring of the impactof rotational cropping systems on weedspecies shifts in direct-seeded rice. Quanti-tative differences were found in relativeabundance of weed species in the WS, whichwere related to DS farming practices. Weedcommunity composition after weed manage-ment was characterized in gogorancah rice(Indonesia) in relation to toposequence andnutrient status. Relative abundance of majorweeds was correlated with position ontoposequence and soil K status.

9. Total and labile C as affected by crop and residuemanagement. IRRI, 1999.

Table 11. Apparent labile soil C (CL) balance (kg ha–1) fromthe 0- to 25-cm depth during catch crop and rice. IRRI,1999.

Treatment Residual CL gain orCL before CL left in loss in

Dry-to-wet catch crop soil after soiltransition Ricea (A) rice harvest (B-A)(DTW) (B)

Fallow 0 N 6107 5971 –136 PU 6107 5462 –645 TU 6107 6140 33

Indigo IR 6107 8708 2601IR+PU 6107 8809 2702IR+TU 6107 9142 3035

Indigo + IMR 6107 8659 2552 mungbean

IMR+PU 6107 9037 2930IMR+TU 6107 9184 3077

Maize MR 6107 7850 1743MR+PU 6107 8815 2708MR+TU 6107 7359 1252

a0 N = no N, PU = prilled urea, TU = tablet urea, IR = indigo residue,IMR = indigo/mungbean residue, MR = maize residue.

negative to low positive balance (–1.4 to 0.8 t ha–1)of CL at all sites. The maize residue mixed with PUproduced a CL balance that was equivalent to thatof the indigo systems. Maize alone or in combina-tion with TU did not have a highly positive balance.The CMI increased with residue incorporation com-pared with the conventional practice adopted byfarmers of keeping the DTW transition fallow. In-digo alone or relayed with mungbean produced abetter CMI than maize. The major effect of residueincorporation on CMI was observed in the soil sur-face layer at all four sites.

7.5

7.0

6.5

6.0

3.0

2.5

2.0

1.5

Total carbon (mg g-1) Labile carbon (mg g-1)

9 Nov 25 Jul 30 Oct

Total C

Labile C

Soil sampling date


● Analyzed research data from past 4 years frommechanical seeder development project inJakenan, Indonesia. Along with NARS col-laborators, designed and initiated a new on-farm participatory study to assess acceptabil-ity of the developed seeder technology.

● Repeated the experiment on yield constraintanalysis in Jakenan for two seasons.

● Analyzed the panel data for 6 years on riskmanagement practices of farmers from easternIndia (Faizabad). The results indicate the im-portance of income diversification strategiesin managing risk at the farm level. Wherefarmers have highly diversified income strate-gies, benefits from stabilization of rice yieldwere quite small. However, in rainfed areaswhere income diversification is constraineddue to environmental conditions or policy fac-tors, stabilization of rice yield can result inmajor gains, especially to poor farmers whohave very limited means for coping with risk.

● Completed a study of the economic cost ofdrought in eastern India and farmers’ copingmechanisms in the event of severe drought.The average production loss in eastern Indiawas estimated to be 8% of the total value ofrice and nonrice output. Drought caused a re-duction in the output not only of rice but alsoof nonrice post-rainy season crops such aspulses and oilseeds. Using farm-level datafrom Orissa, additional costs such as the lossin future production potential due to asset de-pletion, loss of land, deterioration of humanhealth, and other long-term environmental andsocial costs were also documented.

● Completed two papers analyzing the changesin variability of rice area, yield, and produc-tion in eastern India. District-level time seriesdata for 71 districts from eastern India cover-ing the period 1969-94 were analyzed. Themajor findings of the study are: a) productiv-ity growth in eastern India as a whole has ledto an increase in production variance, but therelative variability as measured by the coef-ficient of variation has declined; b) increasedyield instability (both absolute and relative) inparts of Bihar and Orissa are the major con-tributors to increased production instability ineastern India; c) even though there has been a

substantial growth in productivity in easternUttar Pradesh and West Bengal due to expan-sion of irrigation, the yield variability stillclosely tracts the variability of rainfall; and d)the correlation between yield and area has in-creased over time in most eastern districts.

● Conducted stochastic dominance analyses offarm- and district-level yields of modern andtraditional varieties. The results indicate thatmodern varieties are often ‘less risky’ than thetraditional varieties. In several cases, modernvarieties had not only a higher average yieldbut their probability distributions did not inter-sect with those of traditional varieties.

● Assessed the economic value of rainfall fore-cast to rainfed rice farmers in the Philippines.Farm-level panel data showed that the eco-nomic value of simple forecasts such as rain-fall being above or below average was sub-stantial.

● Initiated a joint ICAR/IRRI project to studythe patterns of changes in rice production sys-tems. This comprehensive project uses a com-mon methodology and cover all states of east-ern India.

Germplasm improvement for rainfed lowlandrice

● In Thailand, IR62558-SRN-17-2-1-B was rec-ommended for release as Chao Surin 72 and inLao PDR, IR43070-UBN-501-2-1-1-1 was re-leased as Tha Dawk Kam 4. CN1035-61(IR57540) was recommended for release insemi-deep water (40–70 cm) in West Bengal.Six lines were retained in the All India Coordi-nated Testing Program in 1999.

● In G × E studies, combined analysis of 47 va-rieties across 37 environments confirmed re-peatable G × E interaction across widely dis-persed sites in the rainfed lowlands, which waswell characterized by pattern analysis and pro-vided interpretable groupings of genotypesand environments. Hydrology is identified asthe major discriminating factor and strategiesof drought and submergence tolerance as themain feature of adaptation groups.

● In hybrid rice studies, RL lines were checkedfor the CMS maintainer and restorer traits, andthese appear to be less common than in irriga-


ted lines. Some existing CMS lines and hy-brids from the irrigated program were testedfor adaptability to RL conditions.

● Developed and deployed methodologies foreliciting male and female farmers’ perceptionsof useful traits in rice varietal selection inFaizabad District and Raipur, MadhyaPradesh, and Orissa as well as in the Philip-pines and Vietnam.

● Conducted phenotypic evaluation of a DHpopulation for root-pulling resistance at Ubon.QTLs for this trait were located on chromo-some 4. In addition, identified QTLs associa-ted with root penetration and root thickness onthe same chromosome and located QTLs forosmotic adjustment on chromosome 8.

● Conducted fine mapping of genes controllingsubmergence tolerance at Kasetsart Universityusing the DH population of CT6241/IR49830and the RIL population of FR13A/CT6241.The genes controlling submergence toleranceare located on chromosome 9. Started a MASprogram for selection of genotypes tolerant ofthis stress using F2 and BC populations.

● Found significant QTL × environment inter-action for constitutive root traits with fewQTLs common over populations or runswithin populations. Found a large trans-gressive segregation for deep roots in CT9993/IR62266 and for thick roots in IR58821/IR52561.

● In drought studies, showed that genotypes dif-fered in their ability to perform under droughtand recover on rewatering. Those that ex-tended roots to deeper layers, extracted water,and maintained LAI in drought also recoveredon rewatering. Early vigor and capacity to de-velop roots under drought conditions were ad-vantageous.

● Data from studies of enzyme activity in sub-mergence-tolerant and -intolerant varietiessuggest that an active oxygen-scavenging sys-tem is involved in alleviating damage causedby submergence and desubmergence.

● With several lines identified for cross-toler-ance to submergence and drought by ourbreeders, obtained a close correlation betweenvisual score of damage cause by submergenceand drought separately imposed in the green-house.

● With a computer model, compared andanalyzed (in terms of root-induced solubiliza-tion of P) growth and P uptake by RL cultivarsin soil that was either continuously flooded,continuously moist, or flooded then moist. Inall moisture regimes, the plants relied on solu-bilization for the bulk of their P, but solubili-zation was less effective in re-oxidized,flooded soil than continuously moist soil.

● Tested a screening technique for external Znefficiency based on oxygen release from rootsby comparing an efficient genotype(Madhukar) with an inefficient one (IR26).

● Confirmed varietal differences for bacterialrhizosphere associations governing am-monium oxidation. Based on molecular gene-tic analyses covering a broad spectrum of ni-trifying bacteria including N2-fixing bacteria,variety IR63087-1-17 strongly suppressed thistarget group in its rhizosphere in contrast toMahsuri and KDML 105.

● Through field experiments at URRC (Thai-land), confirmed that root-associated micro-bial communities, unlike those of the bulk soil,maintain their richness of functions inbiogeochemical C and N cycling during anentire cropping season.

Program outlook

Starting in 2000, the Rainfed Lowland Rice Ecosys-tem program will be restructured to include researchin the flood-prone ecosystem.

Ecosystem characterization and resource manage-ment activities will be combined into one project,with emphasis on understanding biophysical andsocioeconomic constraints, characterizing weed andpest problems, developing management practices forefficient use of nutrients and water, and understand-ing farmers’ risk management strategies.

The crop physiology and breeding activities forrainfed lowland and flood-prone environments willbe in a project for germplasm improvement. Thiswill also include activities on farmer participatorybreeding and gender-related studies.

Collaborative interaction with NARS partnerswill continue through the RLRRC and a new col-laborative project, the Flood-Prone Research Con-sortium (FPRC). FPRC’s main objective will be toestablish collaboration and partnerships among sci-


entists and institutes in developing new technologyand to create a mechanism for rapid disseminationof technology to flood-prone rice farming commu-nities.

Research programsUpland rice ecosystem

GENETIC IMPROVEMENT OF UPLAND RICE 48Marker-assisted transfer of quantitative trait loci for root depth to IR64 (PBGB) 48Understanding genetic control of yield loss due to water stress at flowering (APPA, PBGB) 51Rice—a model plant for allelopathy research (APPA, PBGB) 52

Confirmation of allelopathic potential in rice cultivars 52Progress in identification of rice allelochemicals 52Identifying quantitative trait loci correlated with allelopathy 53

Candidate gene profiling to accumulate qualitative and quantitative blast resistance (PBGB, EPP) 53Progress toward a perennial upland rice (PBGB, APPA) 54

Evaluation of perenniality in O. sativa/O. rufipogon F1 progeny 54

Growth and partitioning in perennial rice in flooded and aerobic soils 55Drought tolerance in annual and perennial Oryza species 56

Participatory varietal selection of upland rice in eastern India (PBGB, SS) 58Upland rice research consortium (URRC) 58

PROGRESS OF UNREPORTED PROJECTS 60Improved productivity and sustainability of farming systems in upland rice areas (APPA, SS, SWS) 60

PROGRAM OUTLOOK 60


Upland rice ecosystem

Genetic improvement of upland rice

IRRI has focused germplasm improvement on thegenetic control of plant response to drought anddisease. Different breeding approaches are eval-uated and high priority placed on sharing informa-tion and germplasm with NARS partners. Novelsources of genetic variation are used to developvarieties that can reduce weed pressure and reduceerosion. Grain quality and plant acceptability to thefarmer are particularly important in many small-holder systems where upland rice is grown. Parti-cipatory approaches to varietal evaluation are usedto address that issue.

Marker-assisted transfer of quantitativetrait loci for root depth to IR64B. Courtois, L. Shen, K. McNally, S. Robin,and Z. Li

Drought is a main abiotic constraint in upland riceproduction. A deep root system contributes to themaintenance of crop water status during stress. In1997, we performed quantitative trait loci (QTL)analysis for root parameters on a double haploid(DH) population of rice derived from the crossIR64/Azucena and started a marker-assisted back-cross program to transfer four of the QTLs detectedon chromosomes 1, 2, 7, and 9 from selected DHlines to IR64. The selection scheme is outlined in

Upland rice is grown on about 17 million ha, mostly inAsia (10.5 million ha). About 3.7 million ha of uplandrice are grown in Latin America and 2.8 million ha aregrown in Africa. High levels of rural poverty generallycharacterize upland rice areas. Technological interven-tions are needed to increase the productivity,profitability, and stability of all upland rice-basedsystems.

The goal of upland rice ecosystem research is todevelop technology that will improve the productivityand sustainability of the crop, with the ultimateobjective of reducing poverty. Much of the research inthe upland rice ecosystem program generatesknowledge with application to other rice ecosystemsand other upland crops.

New tools in the field of functional genomics arebeing applied to problems of drought and blastdisease. A novel approach to improving the sustain-ability of upland rice systems in sloping areas is thedevelopment of a perennial upland rice through widehybridization with wild rice species. Crop managementresearch seeks to develop soil-specific recommenda-tions for economical fertilizer rates.

Because rice competes poorly with weeds in direct-seeded (DSR) systems, weed control options that arespecific to rice are required. Research is under way tounderstand the underlying biology of weed inter-ference, both in terms of competition for resourcesand in terms of allelopathic effects.

Socioeconomic factors are particularly significant inupland cropping systems. Improved technologies havetraditionally been adopted slowly by upland ricefarmers and improved understanding of farmers’circumstances and logic is required to developtechnologies that will be adopted.

The diversity of upland systems requires thattechnology be developed and adapted throughexperimentation in the target regions. This is achievedthrough collaboration with national agriculturalresearch system (NARS) partners in the Upland RiceResearch Consortium.

Upland rice ecosystem 49

Table 1. We selected plants with the proper alleliccombination at the target regions based strictly onthe genotype up to BC2F2.

Microsatellite and restriction fragment lengthpolymorphism (RFLP) markers flanking the tar-geted regions used for the genotyping included

● RZ19, RG690, RZ730, and RZ801 for thetarget region of chromosome 1;

● RM29, RG171, RG157, and RZ318 for thetarget region of chromosome 2;

● RM234, CDO418, RZ978, CDO38, andRM248 for the target region of chromosome7; and

● RZ228 and RZ12, replaced by RM201 andRM242 after BC2 generation, for the targetregion of chromosome 9.

We evaluated the proportion of remaining allelesfrom Azucena in the nontarget areas of the BC2F2plants. The theoretical frequency of Azucena allelesin BC3 is 3.1% or less. The whole genome surveywith microsatellite markers showed that the fre-quency of the Azucena alleles in the nontarget re-gions ranged from 0.0 to 6.7% with an average of2.4%. The selected BC3F2 plants are regarded asnear-isogenic lines (NILs) for the target QTLs. Weevaluated the root system of 30 BC3F3 NILs se-lected to represent various recombinant genotypesin the target regions and compared it with that ofIR64 in a replicated greenhouse experiment. Threeof the lines carried Azucena alleles at the target re-gion of chromosome 1 (target 1), five carried target2, seven carried target 7, eight carried both target 1and target 7, and six carried target 9.

The design was an alpha-lattice with six rep-lications, five blocks per replication, and the checkIR64 replicated in all blocks. The plants were grownin tubes 1 m long and 0.2 m diameter filled uni-formly with sandy loam soil. The plants were wa-tered three times a week. The root measurementswere made 43 d after sowing. Maximum root length(point reached by the longest nodal root), total rootweight in the column, and deep root weight (rootweight below 30 cm) were determined.

The main characteristics of the NIL root systemare presented in Table 2. Of the three NILs carryingtarget 1, one had significantly improved deep rootweight over IR64. Three of the seven NILs carryingtarget 7 as well as three of the eight NILs carryingboth targets 1 and 7 showed significantly improvedroot mass at soil depths below 30 cm. This confirms

Tabl

e 1

. S

eque

nce

of o

pera

tion

s in

the

mar

ker-a

ided

sel

ecti

on s

chem

e fo

r in

trog

ress

ion

of Q

TL f

or r

oot

dept

h us

ing

four

DH

lin

es d

eriv

ed f

rom

the

cros

s IR

64

/A

zuce

na a

s do

nors

and

IR

64 a

s re

curr

ent

pare

nt. IR

RI, 1

999.

Plan

tsPl

ants

sele

cted

Sel

ectio

nS

elec

tion

Type

Theo

retic

alPl

ants

with

for

furt

her

Bac

kcro

ssS

easo

nafo

rfo

rof

Prod

uct

stat

usge

noty

ped

desi

red

back

-ge

nera

tion

prim

ary

seco

ndar

ypl

ant

of t

he(n

o.)

geno

type

scr

ossi

ngta

rget

targ

etse

lect

edpr

oduc

t(n

o.)

or s

elfin

g(n

o.)

Hyb

ridiz

atio

n1

99

6 D

SN

oN

oF 1

see

ds75.0

% IR

64

DH

line

s/IR

64

25.0

% A

zuce

naB

C1

19

96

WS

No

No

BC

1F 1

see

ds87.5

% IR

64

12.5

% A

zuce

naB

C2

19

97

DS

Yes

No

Het

eroz

ygou

sB

C2F 1

see

ds93.7

% IR

64

120

33

18

6.3

% Az

ucen

aB

C3

19

97

WS

Yes

Yes

Het

eroz

ygou

sB

C3F 1

see

ds96.9

% IR

64

120

50

15

3.1

% A

zuce

naS

elfin

g1

99

8 D

SYe

sYe

sH

omoz

ygou

sB

C3F 2

see

ds96.9

% IR

64

3.1

% A

zuce

na74

32

32

Who

le-g

enom

e1

99

8 W

SYe

sYe

sB

C3F 3

see

ds312

66

58

s

urve

y

a DS

= d

ry s

easo

n, W

S =

wet

sea

son.


Table 2. Root characteristicsa and other important agronomic traits of the NILs of IR64 evalu-ated at IRRI, 1999.a

Line Target MRL TRW DRW HGT HMG TIL(cm) (kg) (kg) (cm)

IR64 69.1 1.392 0.175 107.4 H 26.3IR74392-108-6 1 75.9 1.699~* 0.146 107.7 H 21.9**IR74392-118-4 1 73.5 1.645 0.279* 150.2** H 23.4*IR74392-135-1 1 70.7 1.669~* 0.233 112.0* OT 27.4

IR74392-201-14 2 72.1 1.230 0.154 110.8 H 19.4**IR74399-204-10 2 65.0 1.173 0.117 105.3 H 20.0**IR74401-215-5 2 70.4 1.333 0.127 101.6** H 23.3*IR74401-215-18 2 73.2 1.424 0.228 . - .IR74401-216-7 2 72.6 1.656 0.194 100.8* H 23.6*

IR74405-711-1 7 64.3 1.510 0.116 101.9* H 24.6IR74405-720-7 7 70.8 1.593 0.278* 122.7** S 25.1IR74405-720-12 7 78.5* 1.572 0.260* 119.5** S 21.0**IR74409-730-8 7 67.9 0.988* 0.100 99.0** H 20.9**IR74409-730-9 7 65.5 1.288 0.103 94.9** H 20.3**IR74409-730-10 7 68.2 1.897** 0.265* 137.1** H 24.5IR74409-734-4 7 65.6 1.471 0.082* 101.9* H 24.7IR74409-735-2 1+7 66.2 1.411 0.222 120.9** S 21.4**IR74409-735-12 1+7 71.6 1.365 0.185 124.3** S 20.9**IR74409-736-11 1+7 74.9 1.807** 0.263* 148.4** H 23.9IR74409-737-5 1+7 75.6 1.616 0.308** 147.4** H 20.2**IR74409-737-12 1+7 69.7 1.685~* 0.302** 123.8** S 23.0*IR74409-738-11 1+7 66.8 1.353 0.150 142.1** H 22.2**IR74409-739-4 1+7 67.9 1.467 0.135 165.8** H 23.8IR74409-739-7 1+7 68.5 1.581 0.106 155.6** H 24.9

IR74418-910-2 9 88.7** 1.585 0.225 109.0 H 23.3*IR74418-910-3 9 71.5 1.271 0.187 107.0 H 22.0**IR74418-910-12 9 72.8 1.212 0.143 109.8 H 23.3*IR74418-913-7 9 79.7* 1.160 0.148 105.8 H 20.6**IR74419-921-1 9 77.9* 1.430 0.153 107.4 H 21.6**IR74419-921-8 9 88.1** 1.306 0.187 105.2 H 21.7**

aMRL = maximum root length, TRW = total root weight, DRW = root weight below 30 cm, HGT = plant height,HMG = homogeneity for plant height (H = homogeneous, S = segregating, OT = off-types), TIL = no. of tillers.~*, *, ** = significantly different from IR64 at 10%, 5%, and 1% thresholds, respectively.

the existence of both QTLs and narrows their loca-tions. Five NILs carrying target 2 were phenotyped,but none had a root phenotype significantly dif-ferent from IR64. A re-analysis of the initial datawith composite interval mapping technique showedthat two QTLs with opposite effects existed in thisarea, even though the initial analysis, which wasconducted using regression on flanking markers,detected only one. The tested lines did not include aroot-increasing recombinant for this segment. Fourof the six NILs carrying target 9 had significantlyimproved maximum root length. Their other rootcharacteristics were similar to those of IR64.

We looked at the influence of these segments onother traits in a field experiment using an alpha-lat-tice design with four replications. Most introgres-

sions seem to decrease tiller number. Improveddeep-root mass (over IR64) seems to be linked withthe presence of the tall allele at the sd-1 locus orheterozygosity at this locus. sd-1 is a recessivesemidwarfism gene located on chromosome 1 be-tween RZ730 and RZ801. However, some tallplants did not display improved root mass. Thiscould indicate tight linkage rather than pleiotropy.

The rate of QTL transfer was not high in thisstudy. There are several possible reasons for that.The first relates to the quality of the initial QTLanalysis—risk of type I error on the QTL existence,uncertainty on QTL position, or existence of non-allelic interactions. The second is that the targetQTL can be lost during the successive backcrossesthrough double crossovers between markers flank-


ing the QTLs. The size of some of the intervals wewere manipulating does not rule out this possibility.Moreover, the fact that the root measurementmethod is destructive and prevents phenotypingduring the NIL production process does not allowelimination of such recombinants.

Our results demonstrated that it is possible totransfer QTLs for root system characteristics in riceand record significant improvement in the root sys-tem. The lines with improved root systems are be-ing tested in the field.

Understanding genetic control of yield lossdue to water stress at floweringR. Lafitte and B. Courtois

The reproductive stage is the period when watershortage most affects grain yield. Our objective wasto document genetic variation in tolerance for waterdeficit during flowering and grain filling among DHlines from a japonica/indica cross, to identify ge-netic markers associated with performance, and toidentify secondary traits that cosegregate with yieldor yield components.

Evaluating drought tolerance at flowering iscomplicated by the fact that genotypes flower at dif-ferent times. Three approaches have addressed thatproblem: sprinkler irrigation with staggered plant-ing dates (1995), furrow irrigation with repeatedmild stress periods that spanned flowering for allentries (1998), and individual plot drip irrigation(1999). The upland japonica cultivar Azucena andthe lowland indica cultivar IR64 were sown in 1999DS along with DH lines from the Azucena/IR64mapping population.

The stress treatment with staggered planting con-sisted of no irrigation for 10 d, with the stress start-ing at anthesis of most of the lines followed by 1 hof irrigation every 3 d until the end of the season.The control was irrigated 1 h d–1 by sprinkler (appli-cation of about 10 mm daily). Irrigation was appliedtwice a week in the future irrigation experiment ex-cept for two periods near flowering (52–64 and 70–84 d after sowing [DAS]) in the stress treatment. Inthe individual drip irrigation experiment, water waswithheld from the stress plots 10 d before 50%flowering of the control plots, and was reappliedafter 14 d.

The staggered sowing in 1995 was not com-pletely effective in inducing synchronous flower-

ing. Some of the lines started to flower well into thestress period. All lines that flowered more than 15 dafter the start of the stress were fully sterile, as weresome that flowered 10 d after start of stress. Linesthat flowered late were eliminated, and the popula-tion used in the analysis comprised 85 DH lines.Genetic differences were observed for most traits.As intended, the stress primarily affected sterility,yield, biomass after stress, and harvest index.

The objective of having two stress periods in1998 was to ensure that all lines would experiencestress during the sensitive period. Water deficit hadlittle effect on tiller number or spikelets per panicleand primarily affected the sterility of panicles andspikelets, and final grain weight. Genetic diffe-rences were detected for these yield componentsand for most other traits.

Data from the first two experiments were sub-jected to QTL analysis, using the genetic map avail-able for the population. Means for each entry wereused to map QTLs for each trait using QTL Mapper1.0. The QTLs identified were compared with thosefound when the population was examined in a low-land ecosystem, under vegetative stress in otherstudies, and with other published data on rice QTLsfor leaf traits and root penetration. They were alsocompared with QTLs for osmotic adjustment iden-tified in other rice populations.

QTLs were identified for almost all traits. Somewere common between stress and control treat-ments, particularly in 1995. When common QTLswere observed, their effects were in the same direc-tion in the two environments, indicating minimalcrossover interaction for those QTLs. A number ofthe QTLs identified for yield components were alsoidentified when the population was grown in fullyirrigated lowland in other studies. On the otherhand, some QTLs were not common across thestress and control plots. These loci represent varia-tion that is water treatment-specific.

Common QTLs were identified across the twoexperiments for plant height, panicle length, tiller-ing, and sterility in the region of chromosome 1 thatcontains the sd1 locus and confers the semidwarfhabit. The same interval has been shown to be asso-ciated with root parameters and also with fieldscores of leaf rolling and drying under water stress.There were several areas where QTLs were associa-ted in repulsion phase (e.g,. for thousand-grainweight under stress on chromosome 3 and for yield


under stress on chromosome 6). QTLs for some sec-ondary traits were found to cosegregate with inter-vals associated with yield or yield components. Formany traits, both parents contributed alleles withpositive effects. Epistasis seemed to explain a non-negligible part of the variability for most traits.Our results show the potential of molecular mark-ers to identify chromosome regions that control theresponse of yield to water deficit at flowering. Fur-ther studies under other drought conditions and withother populations are needed to evaluate therepeatability of these QTLs. It should be possible toidentify QTLs for performance under stress that arenot linked with biomass, and introduce themthrough marker-aided selection into varieties withgood yield potential.

Rice—a model plant for allelopathy researchM. Olofsdotter, L. Bach-Jensen, and B. Courtois

Attempts to increase the competitive ability of ricehave had limited success, in part because of limitedunderstanding of the components and mechanismsof competition. The importance of chemical inter-ference, including allelopathy, in crop competitionhas often been debated. The goals for research onallelopathy have included

● laboratory, greenhouse, and field studies toillustrate the effect of released allelo-chemicals;

● isolation, identification, and characterizationof allelochemicals;

● establishment of correlation between growthinhibition and allelochemicals in controlledexperiments;

● genetic mapping of QTLs correlated withallelopathy; and

● development of cultivars with confirmedallelopathic potential.

IRRI’s research on allelopathy in rice has fo-cused on these goals and has been conducted in col-laboration with several institutions. Rice has be-come a model plant for progress toward utilizationof allelopathy.

CONFIRMATION OF ALLELOPATHIC POTENTIAL

IN RICE CULTIVARS

Field evaluation of weed suppressive activity of ricecultivars was conducted against Echinochloa crus-galli in irrigated lowland fields and againstTrianthema portulacastrum and E. colona in uplandfields. Weeds and rice were direct seeded the sameday in all experiments. During establishment andearly growth of rice and weeds, a range of variableswas measured—e.g., tillering, height, and density ofrice and weed dry weight 8 wk after seeding. TwoN levels were included in the experiments with E.colona to test if N availability interacted with weedsuppressive ability. The results indicated cultivardifferences in the ability to suppress weeds in up-land and lowland irrigated fields.

Rice height was the single most important factorinfluencing weed suppression, accounting for 15–50% of weed reduction. However, looking only atthe most weed suppressive cultivars, rice height wasnot an important factor, meaning that allelopathy insome cases plays a more significant role than any ofthe other features measured. The number of weedsin the field was not affected by rice cultivars butweed height and biomass were strongly dependenton cultivar. The experiments also indicated thatmaximum weed suppression is obtained in cultivarsthat have both allelopathy and competitive traits.

PROGRESS IN IDENTIFICATION OF RICE

ALLELOCHEMICALS

Phenolic acids have frequently been described asallelochemicals, but it is unlikely that they are re-sponsible for allelopathic potential in rice. In col-laboration with the Natural Compound UtilizationLaboratory, USA, isolation and identification ofrice allelochemicals by use of bioassay-guided iso-lation have started. Several putative allelochemicalshave been isolated from roots of Taichung Native 1.Ten of at least 23 compounds have been identified,but none of those alone explains the allelopathic ef-fect seen in the laboratory and the field. If theallelochemicals involved are identified, and if theallelochemicals correspond to genes that are alreadysequenced, the genes will be used as candidateprobes to detect whether they cosegregate withQTLs detected in mapping populations.


IDENTIFYING QUANTITATIVE TRAIT LOCI

CORRELATED WITH ALLELOPATHY

A population from the cross IAC165/Co 39 wasused for mapping the genes involved in allelopathy.The population of 144 recombinant inbred lines wasderived through single-seed descent. A molecularmap of this population contains 184 markers, bothmicrosatellite and RFLPs. The length of the geneticmap is close to 2000 cM. This population wasevaluated both for allelopathic potential and also forcharacteristics related to drought tolerance.

The upland cultivar IAC165 showed strong andconsistent allelopathic activity against E. crus-galliin a study using a relay seeding technique, while theirrigated cultivar Co 39 was weakly allelopathic.

IAC165 is a highly allelopathic cultivar fromBrazil. Laboratory screening showed that a largeproportion of the Brazilian upland rice germplasmis allelopathic. However, weed selectivity, auto-toxicity, and residual effects from Brazilian ricegermplasm differ from those for Asian germplasm.

Candidate gene profiling to accumulatequalitative and quantitative blast resistanceJ.L. Wu,12 P.K. Sinha,13 K.L. Zhang,12 B. Courtois,and H. Leung

Genetic resistance to blast in upland rice is oftenshort-lived due to the disease-conducive environ-ment in the upland ecosystem and the high varia-bility exhibited by the pathogen. Previous work hasdemonstrated that both qualitative and quantitative

resistances are important components of durableresistance, but the masking effect of major resist-ance genes has made it difficult to combine comple-mentary resistance mechanisms.

We have developed an advanced backcrosspopulation (BC3F3) using Moroberekan as the do-nor of qualitative and quantitative blast resistanceand Vandana as the recurrent parent with good qual-ity traits and adaptation to eastern India. EightyBC3F3 lines were evaluated at seedling stage in thegreenhouse and in the blast nursery at IRRI. Wheninoculated with a single pathogen isolate in thegreenhouse, the BC3F3 lines segregated in a bimo-dal pattern, suggesting the presence of major resist-ance gene or genes. In the blast nursery, the BC3F3and BC3F4 populations showed different levels ofresistance among the lines against a diverse patho-gen population, indicating successful introgressionof resistance genes from Moroberekan (Fig. 1).

Molecular markers associated with both qualita-tive and quantitative resistance were identified byuse of 26 candidate resistance genes from rice,maize, and barley as probes to analyze DNA of the80 BC3F3 lines by Southern hybridization. The can-didate genes included 1) major resistance geneswith nucleotide-binding site (NBS) and leucine-richrepeats (LRR), which are conserved domains in-volved in pathogen recognition, and 2) disease-re-sponse genes involved in general defense mecha-nisms. Five NBS-LRR sequences and three disease-response genes showed significant contribution todisease resistance (Table 3).

Table 3. Candidate resistance genes associated with resistance observed in BC3F3lines derived from Vandana/Moroberekan. IRRI, 1999.

Gene categorya

Marker (specific name) Source Chromosomeb Fc P

CG54a NBS-LRR Maize 9 16.01 0.0001 (Rxo-6.31)

CG36b NBS-LRR (Rp1) Maize 1,2 22.54 0.0001CG52 NBS-LRR Maize 10.16 0.0001CG7b PR protein Barley 11 11.49 0.0011

(PR5 thaumatin)CG16a PR protein Barley 11.25 0.0013CG1 PR protein Barley 5.83 0.0181R2d NBS-LRR Rice 11 5.46 0.022R6e NBS-LRR Rice 11 4.7 0.0333

aPR = pathogenesis-related. bChromosomal locations determined using a recombinant inbredmapping population derived from Gumei 2/Zhong 156. cF values from analysis of variance usingthe general linear model. A significant F value supports the hypothesis that the gene markerhas an effect on reducing disease severity as measured by percent diseased leaf area.


To determine whether phenotypic expression ofresistance is associated with specific profiles of can-didate genes, the backcross lines were clusteredbased on the similarity of their DNA banding pat-terns produced by candidate gene probing. About20% of the top performing lines were found in threedistinct clusters in the dendrogram. Genotypes inone cluster were associated with a high level of re-sistance, whereas genotypes in the other two clus-ters showed partial resistance. In contrast, the samehigh-performing lines were scattered in adendrogram generated by microsatellite markers,which are presumably not associated with diseaseresistance except through linkage. The results sug-gest that candidate gene profiling is indicative offunctional resistance and may provide an effectivemeans of combining both qualitative and quantita-tive resistance in advanced breeding lines.

Because the backcross lines have a substantialamount (theoretically 87%) of the Vandana back-ground, suitable commercial varieties could be ex-tracted directly from the backcross lines, or pro-duced by an additional cycle of selection andintercrossing. We are working to extend the pheno-typic analysis to correlate seedling resistance withneck blast resistance in upland sites with high dis-ease pressure.

Progress toward a perennial upland riceE. Sacks, K. McNally, S. Kubota, L. Liu,R. Lafitte, and O. Ito

Upland rice is the main subsistence crop in the hillyareas of Southeast Asia, providing food security vialow (~1 t–1 ha) but stable yields using little or nopurchased inputs. It is grown in a traditional shift-ing cultivation system that has long rotations and isrelatively sustainable, but there is a trend towardshorter rotations and more intensive use of marginallands because of increasing population pressure.The resulting soil degradation directly limits uplandrice yields and indirectly limits water availabilityand farm productivity in lowlands because of silta-tion of reservoirs. A perennial upland rice is one ofseveral possible interventions to address the prob-lem of erosion.

Efforts to develop a perennial upland rice focuson combining genes for perenniality and droughttolerance from O. rufipogon and O. longistaminata,with genes for agronomic acceptability from uplandcultivars of O. sativa. Work in 1999 included morethan 500 cross combinations, initial field testing ofmore than 1,500 O. sativa/O. rufipogon F1 progeny(32 families), and field testing of more than 7,000O. sativa/O. longistaminata progeny (98 S1 fami-lies). A backcross intermating scheme for the O.sativa/O. longistaminata population was estab-lished. Mapping populations were developed fromO. sativa/O. longistaminata crosses, and wereevaluated for rhizome formation. Production of thegenetic map is under way to allow identification ofgenetic markers for rhizome formation.

EVALUATION OF PERENNIALITY IN O. SATIVA/O.

RUFIPOGON F1 PROGENY

Variation for perenniality and drought tolerancewas observed among and within 10 accessions of O.rufipogon in a previous study (IRRI Program Re-port for 1997). Selections from that experimentwere crossed with upland rice cultivars to produceF1 seed. We evaluated perenniality and drought tol-erance of the F1s during 1998-99.

A total of 51 O. sativa/O. rufipogon F1 combina-tions were obtained from six accessions of O.rufipogon crossed with one or more of 14 annualupland rice cultivars. The upland parents included

20

16

12

8

4

0

BC3F3BC3F4

Mor

ober

ekan V

anda

na

5 10 15 20 25 30 35 40 45 50 55Diseased leaf area (%)

Lines (no.)

1. Percent disease leaf area (DLA) of BC3F

3 and BC

3F

4lines derived from Vandana/Moroberekan. The plantswere exposed to natural pathogen popul1ation in the blastnursery at IRRI. Note the normal distribution of thephenotypes. IRRI, 1999.


Table 4. Variation in survival and vigor associated with O.rufipogon parents of F1 hybrids of upland rice cultivars af-ter 1 year of cultivation and 2.5 mo of moderate droughtstress. IRRI, 1999.

Vigorb

Accession Hybrids Survival Rankno.-plant no.a (no.) (%) Mean Std dev

105832-1 73 10 9 5.6 2.6105832-11 26 8 10 7.0 0.0105832-18 7 71 1 5.8 1.3106114-11 8 25 5 4.5 3.5106133-9 54 0 12 – –106138-4 29 66 3 3.8 2.1106138-7 92 35 4 6.0 2.3106138-18 10 70 2 3.4 2.5106144-2 42 7 11 4.7 2.3106144-18 26 12 7 6.3 2.1106340-1 93 11 8 4.2 1.5106340-2 41 12 6 5.4 4.5

aIdentification of O. rufipogon parents of F1 hybrids. bData for survi-

vors only. Based on a 1-9 scale, where 1 is best.

indica and japonica varieties from Asia, LatinAmerica, and Africa.

We evaluated 501 F1 individuals and their annualparents in an IRRI upland field. Plots were estab-lished in Jul 1998 as two rows of plants in each of10 concrete-lined beds. To evaluate drought toler-ance, no supplemental irrigation was provided from15 Mar 1999 (during DS) until the end of the experi-ment. Due to above-average rainfall for March,April, and May, entries were exposed to modestdrought stress. Entries were scored for survival 30Jun 1999 and survivors were rated for vigor. Sur-vival of the F1 individual O. sativa parent and O.rufipogon parent, and their interaction, were as-sessed using SAS procedures CATMOD andFREQ.

None of the annual controls had survived by theend of the experiment, indicating that the O. sativaparents were not perennial. Ninety-five F1 plants(~19%) survived, indicating that genes forperenniality from O. rufipogon were expressed insome F1s. Moreover, the perenniality observed inthe F1s and derived from the O. rufipogon parentsmust have been the result of nonrecessive gene ac-tion.

Interactions among the O. sativa and O.rufipogon parents and the main effect of O. sativaparent were not significant. Although the O. sativaparent and parental combination did not have a de-tectable effect on survival, we interpret these datacautiously in light of the incomplete crossing de-sign. The effect of O. rufipogon parent was highlysignificant (P <0.001 for chi-square of 115 with 11df). Survival of F1s ranged from 0% for parentalaccession 106133 (plant 9) to 71% for accession105832 (plant 1) (Table 4). The second, third, andfourth ranked O. rufipogon parents for survivalwere from accession 106138 and the fifth rankedparent was from accession 106114. Those two ac-cessions were the best in a previous report ofperenniality in wild species (IRRI Program Reportfor 1997).

Our results are encouraging. Recombination andselection should allow identification of progeny thatare perennial and agronomically desirable. F1s thathad the highest vigor scores at the end of the studyare currently being intercrossed using nested andfactorial designs.

GROWTH AND PARTITIONING IN PERENNIAL RICE

IN FLOODED AND AEROBIC SOILS

An experiment determined how different soil condi-tions (flooded vs moist-aerobic) and daylength af-fected growth and development in O.longistaminata, O. sativa, and their interspecificprogeny. Two O. longistaminata accessions(WL02-2 and SL313-13), two O. sativa cultivars(BS125 and UPLRi-5), two BCLF2, and two BCLF1intercrosses were studied. Culm emergence was re-corded each day, and flowering date was recordedfor each culm. Five plants of each genotype werecollected at flowering, separated by plant part (rhi-zome, aboveground shoots, and roots), freeze-dried,and weighed.

The upland cultivars and perennial genotypesgrew better in flooded soil than in moist aerobicsoil, producing more culms, panicles, total plant dryweight, aboveground shoot dry weight, and root dryweight in flooded soil (Table 5). The perennialgenotypes had greater rhizome dry weight inflooded soil than in aerobic soil. The data (Table 5)demonstrate that variation in tolerance for aerobicsoils exists in O. sativa and O. longistaminata.

For the perennial genotypes, the proportion ofrhizome dry weight to total dry weight was largerfor aerobic soil than for flooded soil, primarily be-cause plants maintained the production of rhizomesbetter than the production of aboveground parts.The maintenance of rhizome mass under moisture


Table 5. Dry weight of each plant part, fraction of dry matter in rhizome, culm and panicle production at flowering forannual and perennial rice grown in flooded and moist aerobic soil. IRRI, 1999.

Distribution TotalSoil Entry Total Top Rhizome Root ratio in culms Panicles

(g plant–1) (g plant–1) (g plant–1) (g plant–1) rhizome (%) (no. plant–1) (no. plant–1)

Flooded BS125 86.3 78.4 0.0 4.9 0.0 8.1 8.1UPLRi-5 42.8 39.5 0.0 3.2 0.0 5.9 5.9WL02-2 135.3 107.3 16.1 5.5 12.0 26.7 8.6SL313-13 76.2 58.3 12.7 3.1 17.0 37.9 9.5IR73352.30-4 127.0 105.6 4.3 7.8 3.4 83.4 26.0IR73354.3-2 56.8 51.1 2.4 2.2 4.0 43.3 15.7B52.19/54.36-1 129.4 109.3 5.6 6.4 4.4 49.5 26.0B54.17/6-2 66.0 61.4 1.7 2.0 2.6 37.0 22.8

Moist, BS125 21.5 18.0 0.0 2.0 0.0 2.7 2.7aerobic UPLRi-5 22.2 18.4 0.0 2.1 0.0 2.7 2.7

WL02-2 43.1 25.1 11.7 3.3 26.6 8.9 2.1SL313-13 37.4 22.7 10.3 2.9 30.2 10.2 1.0IR73352.30-4 27.9 21.3 1.6 3.8 5.7 38.3 3.9IR73354.3-2 13.0 10.2 1.0 0.8 7.8 18.7 4.8B52.19/54.36-1 32.2 23.4 1.9 3.6 5.9 19.8 7.0B54.17/6-2 18.0 14.8 1.3 1.1 7.9 8.4 1.2

Signifi- Water ** ** ** ** ** ** **cance Progenies ** ** ** ** ** ** **

stress should allow long-term survival in difficultenvironments.

The perennial genotypes flowered over a longertime period (45–60 d) than the cultivars (~20 d).The ability to flower over a long period of time maybe a useful trait for developing cultivars that havestable yield because some panicles will avoid waterstress at critical stages. The effect of flowering du-ration on yield stability and yield potential shouldbe investigated further because subsistence farmerstypically prefer yield stability over yield potential.The number of flowering culms produced by the O.longistaminata genotypes was similar to that of thecultivars even though the wild species producedmany more culms. The plants grown in aerobic soilshowed patterns of shoot development and flower-ing similar to the plants in flooded soil. Because ofpoor seed set in the perennial plants, it was not pos-sible to determine the implications of competitionbetween vegetative and reproductive sinks duringgrain filling.

DROUGHT TOLERANCE IN ANNUAL

AND PERENNIAL ORYZA SPECIES

Perennial upland rice will have to survive a dry sea-son (DS) and also withstand dry periods during therainy season.

Fifteen genotypes, including upland and lowlandvarieties of O. sativa and accessions of O. rufipogonand O. longistaminata, were evaluated in long tubesin the greenhouse during DS. Treatments includedwell-watered, medium water stress, and severe wa-ter stress. Stomatal resistance and root bleeding dif-ferences were detected early in the water-stress pe-riod. The correlation between stomatal resistanceand biomass production, root depth, and root dryweight was significant. A close correlation was alsofound between stomatal resistance and visualdrought screening score (r=0.84**) and stomatalresistance and leaf relative water content (RWC)(r=0.88**), traits that are often used to assessdrought tolerance under severe water deficit.


Significant differences in drought tolerance(measured as biomass production) were foundamong the varieties and among accessions of thewild species. All O. longistaminata accessions andmost O. rufipogon accessions were more tolerantthan O. sativa, but only one O. rufipogon accessionwas as tolerant as the O. longistaminata entries. Thewild species produced relatively more biomass un-der stress, had deeper root systems and higher leafRWC and stomatal conductance (Table 6). Somewild accessions had much greater membrane stabil-ity, root sap production, and osmotic adjustmentthan the cultivated varieties. Contrasting strategiesfor productivity and survival were apparent amongthe genotypes tested. The superiority of the tolerantO. rufipogon accession was confirmed in fieldevaluations of O. sativa/O. rufipogon progeny.

Among all the traits tested, root dry weight dis-tribution with depth appeared to be particularly im-portant (Table 6). This trait was closely correlatedwith other traits, such as leaf RWC, stomatal resist-ance, shoot biomass production, and root sap pro-duction. Under water deficit, varieties with dramati-cally reduced shoot biomass production also suf-fered reductions in root growth. No decline was ob-served in root growth in varieties that maintainedbetter shoot biomass production. Furthermore, theroot systems of tolerant varieties showed a redistri-bution of dry matter to deeper soil levels understress. Differences in root growth and distributionbetween drought-tolerant and -susceptible rice va-rieties may be due to abscisic acid analog (ABA) orother chemical signals.

Although root characteristics may be importantfor drought tolerance, it is difficult to analyze rootdry weight and distribution in large-scale screening.Our results indicate that stomatal resistance undermoderate water deficit may reflect root distribution.Shoot traits such as leaf membrane stability and os-motic adjustment are important for survival undermore severe stress and for recovery ability. Plantsthat combine superior root and shoot traits will besought among the interspecific progeny being pro-duced.

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Participatory varietal selection of upland ricein eastern IndiaB. Courtois, D. Chaudhary, G.N. Mishra,13

N.P. Mandal,13 K. McAllister, S. Pandey,T. Paris, K. Prasad,13 A.T. Roy,26 R.K. Sahu,24

V.N. Sahu,24 S. Sarkarung, S.K. Sharma,24

A. Singh,11 H.N. Singh,11 O.N. Singh,11

N.K. Singh,27 R.K. Singh,13 S. Singh,11 P.K. Sinha,13

B.V.S. Sisioodia,11 and R. Takhur27

A participatory plant breeding project for rainfedrice was developed by plant breeding institutes ineastern India in collaboration with IRRI to test thehypothesis that farmer participation in one or moresteps of the breeding process can substantially in-crease the suitability of modern rice varieties forrainfed environments. The project includes the up-land and rainfed lowland ecosystems and encom-passes plant breeding and social science. Plantbreeders and social scientists work with farmers ina participatory mode.

Field trials represented various hydrological situ-ations in three to five villages in areas where uplandand rainfed lowland rice is grown. Sets of 15–25varieties were tested both in farmers’ fields and on-station in 1997 and 1998 and ranked by farmers andbreeders. The quality of their agreement was meas-ured by the Kendall coefficient of concordance forthe agreement within group (W=1.0 in case of per-fect agreement) and by rank correlation coefficientsfor the agreement between groups. Coefficients ofconcordance among farmers were generally signifi-cant, showing that farmers’ rankings were not ran-domly allocated, even though the agreement withinthe group was not always strong. This indicates thatsocioeconomic diversity among farmers, which weassumed would have generated differences in selec-tion criteria, was lower than expected. Concordanceamong breeders was high, except at one site, but alimited number of scorers was involved and it wasseldom significant. In about two-thirds of the cases,there was a good agreement among farmers’ andbreeders’ rankings. The consensus was particularlystrong when severe constraints induced contrastingbehavior in the genotypes.

Genotype-by-environment (G × E) interactionsfor grain yield were evaluated through variousmethods, showing more effect of G × E interactionsat some sites than at others. Crossover interaction,

which changes varietal ranks from site to site, andis the most damaging G × E interaction componentfor breeders, represented a limited part of the yearlyG × E interactions at all sites.

Farmers in several villages identified varieties ofinterest among the ones they evaluated and decidedto test them in their own fields to confirm their firstimpression. This indicates that access to new varie-ties can also be a constraint to adoption.

Postharvest traits such as cooking quality andtaste are additional factors that influence the proba-bility of a variety’s adoption. A sensory evaluationof varieties was conducted with farmers in Korahar,Bihar. Twenty-four farmers (12 women and 12men) evaluated 15 upland varieties as raw rice andparboiled rice for milled rice appearance, cookedrice appearance, color, odor, texture, stickiness,taste, and overall acceptability. The rice sampleswere milled and cooked by the women farmers fol-lowing their ordinary practices.

One variety recorded good results with bothmodes of preparation (Table 7). The preferences ofwomen and men farmers did not differ significantly.Most of the traits ranked by farmers were highlycorrelated with overall acceptability, indicating thatit is possible to reduce the number of traits scoredby farmers. The rankings based on preferences werepoorly correlated with the rankings of the varietiesfor various physicochemical characteristics meas-ured in the laboratory. The correlation betweenranking based on preferences and ranking based onfield performance of the varieties was positive forraw rice and negative for parboiled rice. The farm-ers’ trade-off between field performance and grainquality is therefore important to assess, at least forparboiled rice. The results of the first sensory evalu-ation will be used to simplify the methodology, ex-tend it to other villages involved in the project, andimprove varietal evaluation in the formal breedingprocess.

Upland Rice Research Consortium (URRC)R. Lafitte

Workplan meetings for 1999 were held at eachURRC site. The annual Steering and TechnicalCommittee Meeting was held at Ranchi, India,11–14 Oct. Sixteen scientists from India, 23 scien-tists from other NARS, and 12 IRRI scientists at-


Tabl

e 7

. S

um o

f sc

ores

a gi

ven

by 2

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r co

okin

g qu

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terist

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of u

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998.

Mill

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ure

appe

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(sof

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tyR

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72

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812

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11

20

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120

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613

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512

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614

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51

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711

14

12

12

16

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713

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12

215

915

11

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516

811

812

912

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tended. Participants examined farmer-participatoryvarietal selection experiments as well as on-stationtrials in Hazaribagh.

More than 40 collaborative URRC experimentswere conducted among IRRI and NARS scientists.A complete flora of upland weeds was publishedand distributed to research partners. More than 20research publications and communications werepublished based wholly or in part on collaborativestudies undertaken under the URRC.

Through collaboration with Centre de coopera-tion internationale en recherche agronomique pourle developpement (CIRAD, France), computer soft-ware for climate analysis and prediction of waterdeficit in upland rice cropping areas was translatedinto English and made available to URRC partners.


Improved productivity and sustainabilityof farming systems in upland rice areasT. George, S. Pandey, M. Kondo, J.C. Castella,M. Mortimer, V. Murty, and G. Kirk

● A survey of 980 upland farmers in northernVietnam indicated that land and labor pro-ductivity and income were highest in market-accessible areas. Upland rice provided foodsecurity in areas with poor market access. Amethodology to study village accessibility tomarket, education, health services, and tech-nical information has been developed.

● Work started on an inventory of technicalinnovations for upland rice-based croppingsystems. Interventions that might increaseproduction in sloping areas include the intro-duction of short-duration upland varieties,setting up production groups for high-qualityseeds of Bao Thai rice in partnership withGRET (a French NGO), and introduction ofcover crops and mulching techniques. Theseare being evaluated.

● A mechanistic mathematical model describingthe processes involved in amelioration of sub-soil acidity was developed. We concluded thatmanagement options could be developedbased on the ideas of leaching down the effectsof surface-applied lime and using acid-tolerantrice to help capture the leached solutes in thesubsoil.

● Field- and laboratory-determined P buffer co-efficients from the Long-Term PhosphorusExperiment sites are being compared to arriveat better estimates of this coefficient. Labora-tory-determined coefficients seem to be stableacross crop seasons. In contrast, field coeffi-cients decline with time after an initial spikethat follows P fertilization.

● Collaborative experiments with the PhilippineRice Research Institute indicated high produc-tion potentials for Philippine upland Ultisolswhen adequate lime, N, and P were applied.Ultisols cover more than 8 million ha in thePhilippines. Yields of 2 t ha–1 for peanut and 6t ha–1 for maize were achieved on an uplandsite previously considered unsuitable for crop-ping. Data are being used to test model param-eters for a Decision Support System and a Nu-trient Management Support System, and toevaluate the yield predictions from these mod-els.

● Upland rice in field experiments in India, Phil-ippines, and Thailand was found to be moresensitive to water stress than N uptake and sen-sitivity was greater during the reproductivestage. Water stress seemed to cause a rapiddecrease in water potential in the stem basebefore leaf water potential decreased, possiblyindicating poor water extraction by upland riceroots compared with water transport within theplant.

Program outlook

The Upland Program will continue to focus on ar-eas where problems of poverty, population pressure,and environmental degradation demand improvedtechnologies.

The largest area of upland rice in Asia is in east-ern India, where upland rice is grown in permanentrice-based cropping systems. We will increase ouremphasis on understanding the socioeconomic cir-cumstances of farmers in the area and their capacityto adopt improved technologies.

We will continue to use emerging technologiesin functional genomics to discover the genes andtraits that confer greater drought tolerance and dis-ease resistance. We will develop additionalpopulations from superior donor lines and evaluatethose in target environments through collaboration


with NARS. This upstream research is being linkedto impact by involving endusers of technology inthe evaluation process, through farmer-participatoryvarietal selection.

The long-term sustainability and profitability ofhigher yielding upland rice systems is being exam-ined in multiyear fertility trials. Much of this workwill have direct application to upland rice systemsin Bangladesh and elsewhere.

Another important upland rice system is found inIndonesia and the Philippines. Key issues in thesehighly market-integrated systems include yieldlosses due to disease and the need for technologiesto reduce production costs. We will build on our ini-tial candidate gene analysis to understand the spe-cific resistance genes in different varieties and seekdurable resistance to blast disease.

Upland rice grown in zero-tillage systems ishighly profitable in Brazil. We will work to bringzero-tillage technology to Asian upland rice farm-ers.

Upland rice area in the traditional sloping re-gions of Southeast Asia has declined in the past dec-ade due to government policies, improved marketintegration, and declining yields due to reduced fal-low periods in traditional swidden systems. None-theless, recent reports indicate that adequate uplandrice production remains essential for the food secu-rity of rural households in remote and marginal ar-eas. Even when rice surpluses exist in the lowlandsin a country, these do not translate into adequate ricefor upland farm families.

Our project on perennial upland rice has madesignificant progress, and we anticipate that cultivarswill soon be available for testing by farmers in ero-sion-prone upland areas. Spillover benefits fromthis project include the identification of valuabletraits for nematode resistance and tolerance for wa-ter deficit in wild Oryza species. We will work totransfer these traits to annual varieties.

Weeds are a major constraint to upland rice pro-duction. We will continue to evaluate genetic varia-tion in weed competitiveness, with allelopathy as acomponent trait. We will focus the allelopathy re-search on identifying the chemicals responsible forobserved variation and on its underlying geneticcontrol. We will also examine management andgermplasm options to improve the early growth ofupland rice, to make the crop more competitive withweeds.

Upland rice area is increasing dramatically in thetropical and subtropical areas in China due to scar-city of irrigation water to grow lowland rice. To im-prove the ability of rice to function as a fully aero-bic crop in these systems, we will undertake workto clarify the underlying biology of aquatic adapta-tion. At the same time, we will devise managementsystems that will control weeds and supply nutrientseffectively to aerobic rice.

Our research focus will be guided by the priorityproblems identified through our URRC partners.We will reorganize our consortium activities tobuild on the capacity for upland rice research thathas developed in NARS.

Research programsFlood-prone rice ecosystem

CROP AND RESOURCE MANAGEMENT TO IMPROVE PRODUCTIVITYAND SUSTAINABILITY OF FLOOD-PRONE RICE 64Land and water management effect on acid sulfate soils, Mekong Delta, Vietnam (SWS) 64

GERMPLASM IMPROVEMENT 65Genetic analysis of rice grain mineral density (PBGB) 66

Rice grain mineral density 66Combining ability analysis of rice 66

QTL underlying phosphorus deficiency tolerance in rice (PBGB, SWS) 69Phenotypic performance to P deficiency 69AFLP-RFLP-SSLP map 70QTLs for P-deficiency tolerance 70

IRRI lines named as varieties for saline-prone areas (PBGB) 76

PROGRAM OUTLOOK 76


Flood-prone rice ecosystem

Crop and resource management toimprove productivity and sustainability offlood-prone rice

The project objectives are:● evaluate socioeconomic and biotic constraints

to productivity of flood-prone rice,● analyze the role of mineral elements in

flooding tolerance and productivity of ricecultivars, and

● determine the potential effects of globalwarming and changing weather on flood-prone rice land.

Land and water management effect on acidsulfate soils, Mekong Delta, VietnamT.P. Tuong

Understanding of changes in soil quality as affectedby land use and water management will help in de-velopment of land and water management strategiesfor fragile acid sulfate soil environments. We col-laborated with the Southern Institute of Water Re-sources Planning, Vietnam, to investigate 1)changes in chemical properties of a newly re-claimed acid sulfate soil with different land uses(rice cultivation vs fallow) and 2) variations in soilproperties as a function of distance from adjacentdrainage canals.

The research was done at the Tan Thanh experi-mental farm in the Mekong River Delta. Soil at thesite was classified as very fine Typic sulphaquept.The whole area is subjected to annual flooding to adepth of 1–1.5 m from September to December. The5-ha farm was divided into four plots. Drainage ca-nals at 100-m intervals were along the length of the

There are about 12 million ha of flood-prone riceworldwide, 95% of which is in South and SoutheastAsia. Priorities of the flood-prone ecosystem programinclude socioeconomic studies on changes occurringin the ecosystem, research on nutrient availability andsoil toxicity, and resource management. The researchis in three projects: 1) crop and resource manage-ment, 2) germplasm improvement, and 3) the Flood-prone Rice Research Consortium. The consortium wasestablished in partnership with concerned nationalagricultural research systems (NARS). The main goalis to formulate and test technology that will promotesustainable, stable production systems.

Flood-prone rice ecosystem 65

plots. Two plots were left fallow in their naturalcondition. The other plots were cleared. They hadbeen in rice cultivation since 1990 with two ricecrops annually from January to August. Aluminumconcentration at 10–20 cm and 40–50 cm depth inall plots was measured monthly at 3, 9, 25, and 50m from the adjacent canals.

Figure 1 shows Al3+ concentration in soil solu-tion for both types of plot as a function of distancefrom the adjacent canal. Aluminum concentrationtended to increase in both plot types as distancefrom the drainage canals increased.

The surface soil (0–20 cm depth) in the culti-vated plots had been tilled, during which farmersdrained surface water to remove acidity. Those ac-tivities made the soil more homogeneous across thefield, resulting in no significant differences in Al3+

concentration across the field (Fig. 1a).Soils in the fallow plots and at 40–50 cm depth

in the rice plots were not affected by land prepara-tion and their Al3+ concentration depended on ver-tical leaching. As a result, Al3+ concentrations werehighest at the center of the field. Leaching was ef-fective only at distances less then 25 m from thecanals. Thus drainage canals should be no morethan 50 m apart.

Figure 2 shows the 1990-93 changes in soil so-lution Al3+ concentration at 40-50 cm depth. TheAl3+ concentration in the rice plots decreased sig-nificantly (p <0.001), while there was no significant

30

25

20

15

10

5

03 9 25 50 3 9 25 50

a b

Al3+ (meq L-1)

Distance from drainage canal (m)

LSD5% depth 10/20 cm

LSD5% depth 40-50 cm

Depth (cm)10-2040-50

1. Soil solution aluminum (Al3+) concentration at 10–20 cm and 40–50 cm depths in (a) plot double-cropped with riceand (b) fallow plot, as affected by distance to adjacent drainagecanals. Tan Thanh, 1999.

2. Temporal changes in soil solution aluminum (Al3+)concentration at 40–50 cm depths in (a) plot double-cropped withrice and (b) fallow plot. Points designate the means of sevensampling site; vertical bars are standard deviations of the means.Tan Thanh, 1999.

change in the Al3+ concentration in the fallow plots.Leaching by the ponded water layer was responsi-ble for the decrease of Al3+ in the rice plot.

Land preparation, surface water drainage, andleaching by ponded surface water improved the top-soil of acid sulfate rice fields. Flushing and leach-ing activities, however, transfer acidity from thefields to the surrounding area and may contribute toenvironmental degradation.

Germplasm improvement

Germplasm improvement focuses on developingcultivars adapted to flood-prone environments.DNA-based molecular marker-aided selection(MAS) techniques were used to increase selectionefficiency and permit simultaneous selection for anumber of traits. Research focused on abioticstresses and high micronutrient in rice grain.

Al3+ (meq L-1)20

15

10

5

0

25

20

15

10

5

0May 1991May 1990 May 1992 May 1993

Time

a

b

10-20

40-50


Genetic analysis of rice grain mineral densityTin Htut, G.B. Gregorio, D. Senadhira,R.D. Graham,28 G.S. Khush, R.O. Mendoza,and A.N.R. Monroy

Enhancing essential micronutrients in food cropsthrough breeding requires understanding of the na-ture of combining ability among donor and recipi-ent rice germplasm and development of appropriatebreeding strategies. Only limited information isavailable for such a study in rice.

Crossing nine parental rice varieties in all pos-sible combinations developed a nine-parent diallelpopulation. The parental rice varieties involvedwere Azucena, Basmati 370, BG300, IR64,IR68144-2B-2-2-3, IR72, IR74, Madukhar, andXua Bue Nuo.

Azucena, Basmati 370, Madukhar, and Xua BueNuo were selected as donor rices for their high grainFe and Zn density as a result of preliminary germ-plasm screening at IRRI. Azucena is an upland va-riety classified as a tropical japonica. Basmati 370is an aromatic variety classified as indica.Madhukar is a traditional Indian variety adapted toZn-deficient soils. Xua Bue Nuo is a Chinese tradi-tional red variety whose name means iron. The re-cipient parental varieties (BG300, IR64, IR72, andIR74) have high yield potential. IR68144-2B-2-2-3is an improved rice line with enhanced micronutri-ent density.

Seedlings of all 72 crosses and 9 parental geno-types were transplanted in experimental plots. Ex-tra care was taken to avoid mineral contaminationof seeds throughout sampling and sample prepara-tion. Manually dehulled rice samples were analyzedfor grain mineral density by inductively coupledplasma atomic emission spectrometry at the PlantScience Laboratory, Waite Agriculture ResearchInstitute, University of Adelaide, Australia. Themean of two subsamples for grain Fe, Zn, Ca, Mg,Cu, Mn, P, S, and K density was subjected to diallelanalysis. Only F1s and reciprocal F1s were includedin the data analysis for unbiased estimates of gen-eral combining ability (GCA) of the parent rice va-rieties.

RICE GRAIN MINERAL DENSITY

The mean grain mineral density (GMD) values ofthe nine parents, when compared with their respec-tive crosses, exhibited large differences in eitherpositive or negative direction, suggesting heterosisof GMD. The range of grain Fe density was from9.01 to 19.18 ppm, with maximum value in thecross Azucena/Basmati 370 followed by IR68144-2B-2-2-3/Madukhar, Azucena/Madukhar, Basmati370/Xua Bue Nuo, and Azucena/Xua Bue Nuo, andthen by Madukhar/Xua Bue Nuo and Azucena/IR68144-2B-2-2-3. All high-Fe density crosseswere also found to be high for grain Zn and otherGMD. The maximum value (49.25 ppm) of grainZn density was observed for Azucena/Basmati 370followed by IR68144-2B-2-2-3/Madukhar andAzucena/Madukhar. The variability of the crossesfor GMD was determined by their coefficient ofvariation (CV) across the population. The largestCV was observed for grain Zn (30.38%), followedby Fe (19.54%), Mn (17.31%), and P (14.56%). Thediallel crosses varied largely for grain Zn densityfollowed by grain Fe. Thus the selection for grainZn density would be the most effective in this set ofcrosses.

COMBINING ABILITY ANALYSIS OF RICE

Highly significant variations among 72 crosses forthe density of Fe, Zn, Ca, Mg, Cu, Mn, P, S, and Kin grain were observed (Table 1). Highly significantGCA, specific combining ability (SCA), and recip-rocal mean square for all GMD were also observedwhen variations among the crosses were partitionedinto GCA, SCA, and reciprocal sums of square.Except for grain Cu density, R2 (coefficient of de-termination) for all GMD was high, indicating fit-ness with the additive dominance model.

The GCA effects of the parent rice varieties wereboth positive and negative for all GMD. Varietieswith positive GCA effect for most of the grain min-erals were Azucena, Basmati 370, IR68144-2B-2-2-3, Madukhar, and Xua Bue Nuo (Table 2). This sug-gests GMD is heritable. All high-yield-potentialvarieties showed negative GCA for GMD, suggest-ing that they did not contribute to increase in min-eral density traits of rice. Xua Bue Nuo showedhighest GCA effect on grain Fe density. Madhukar


Tabl

e 1

. A

naly

sis

of v

aria

nce

for

rice

gra

in m

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1999.

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licat

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21

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ns8.2

3ns

351.9

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15468.5

2*

0.0

8ns

10.1

86ns

9594.9

1ns

3272.6

9ns

328692.1

3*

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sses

7

21

8.1

3**

188.2

6**

324.1

4**

90820.9

7**

1.6

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94.7

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1030020.8

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70142.9

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281390.1

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com

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941.7

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2101.0

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429487.5

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627.3

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129.9

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Because magnitude of the GCA effect of a par-ent varies depending on the mineral elements, theassociation of GCA effects of parents on nine min-eral nutrients was examined. High correlation coef-ficients among GCA effects on some mineral den-sity were generally observed (Table 3). However,GCA effects of the parents on Zn and Ca mineraldensities showed low correlation.

The GCA effects of the parent rice varieties ongrain Mn and other grain minerals, except S, alsohad low correlation coefficients. This suggests thatbasing parental selection on GCA to breed for en-hancing the GMD cannot be applied for enhancingthe overall mineral concentration of the rice grain.This may be due to the fact that parental varietieswere originally selected only for high Fe and Zn.

Choosing parent rice varieties based on one ortwo mineral nutrients may upset the biologicallyimportant ratio of grain minerals in future rice vari-eties. Therefore, breeding for enhancing grain min-eral elements should aim for optimization of min-eral elements important for human nutrition and forselection strategies for multiple mineral traits.

Highly significant SCA across mineral elementswas observed (Table 3). However, there were sig-nificant negative correlation coefficients betweenSCA effect on grain Ca and other minerals such asMg, Mn, P, S, and Zn. The SCA effect on grain Mnalso showed negative correlated effect on grain Cu,Fe, K, Mg, Mn, P, S, and Zn. Therefore, selectionbased on SCA of specific crosses for GMD wouldhave negative effect on other grain minerals.

Our results suggest that selection based on SCAshould be done on the most nutritionally limitedgrain minerals and with the condition that negativeconsequences on other minerals not alter either thehuman or plant nutritional requirement. An alter-native is selection based on the index form of mul-tiple GMD. The correlation among GCA and SCAeffects on the nine mineral densities could be con-sidered as genotypic correlation. This relationshipcan still be modified by environment, cancellationeffect, and opposition between GCA and SCA ef-fects as shown in phenotypic correlation among themean density of each mineral nutrient based on F1sand reciprocal F1s. There is no negative relation-ship, suggesting some cancellation effect of GCA


Table 2. General combining ability effects of nine rice genotypes for grain mineral density in 9 × 9 diallel population.IRRI, 1999.

Mineral elementsParent

Fe Zn C Mg Cu Mn P S K

Azucena 1.13 6.26 –6.59 124.51 0.14 4.38 395.11 34.22 298.2Basmati 370 0.61 3.10 –2.19 22.13 –0.20 6.74 171.30 –12.57 126.85BG300 –1.84 –6.24 –2.37 –138.11 –0.57 –4.17 –451.32 –61.73 –177.91IR64 –1.55 –4.72 –6.25 –94.66 –0.52 –3.36 –362.04 –51.49 –188.62IR68144 0.87 –0.03 9.79 44.63 0.02 3.41 108.20 16.01 37.57IR72 –1.63 –4.15 3.33 –102.16 –0.04 –1.03 –367.99 –79.35 –199.34IR74 –1.18 –2.56 –9.95 –62.28 0.20 –2.44 –266.80 –92.21 –181.48Madhukar 1.75 6.50 7.54 91.30 0.07 –2.57 351.06 160.77 119.71Xua Bue Nuo 1.82 1.83 6.68 114.63 0.88 –0.96 422.49 86.36 164.95 SE 0.15 0.28 0.74 9.64 0.10 0.34 27.99 9.57 22.12

Table 3. Correlation coefficients among general combining ability (GCA) effect and specific combiningability (SCA) (in parenthesis) of parent rice varieties on grain mineral density. IRRI, 1999.

Ca Cu Fe K Mg Mn P S

Cu 0.35(–.15)

Fe 0.53 0.66*(–.29) (0.79**)

K 0.27 0.52 0.91**(–.27) (0.66**) (0.74**)

Mg 0.39 0.69* 0.97** 0.95**(–38*) (0.74**) (0.92**) (0.88**)

Mn 0.07 0.15 0.49 0.66 0.53(0.69**) (–6**) (–3**) (–35*) (–0**)

P 0.41 0.67* 0.98** 0.96** 0.99** 0.54(–38*) (0.75**) (0.90**) (0.91**) (0.99**) (–9**)

S 0.61 0.49 0.89** 0.75* 0.83* 0.14 0.85**(–34*) (0.81**) (0.91**) (0.83**) (0.96**) (–2**) (0.95**)

Zn 0.26 0.49 0.90** 0.92* 0.92** 0.56 0.94** 0.81*(–44*) (0.73**) (0.89**) (0.83**) (0.96**) (–0**) (0.96**) 0.94**

and SCA or environment. Phenotypic correlationamong GMD also showed that Fe and Zn werelargely and significantly correlated with P, S, and K(Table 4).

Crosses with high SCA effects were IR64/XuaBue Nuo, IR72/Madukhar, IR68144-2B-2-2-3/IR72, IR64/IR74, and IR64/IR72. However, selec-tions based on SCA alone cannot guarantee higherGMD because SCA was composed of dominanceand some type of epistasis components. When therelative importance of GCA and SCA for GMD wasconsidered, the suggested ratio of GCA and SCAshowed 0.87 and higher for all grain minerals (Ta-ble 5).

Our results indicate that GMD of a single crosscan be highly predictable based on the GCA of the

parent rice varieties. Primary selection should bedone based on GCA, followed by selection based onSCA for better cross combination coupled with theirmean performance. When the correlation betweenSCA effects of each cross and their GMD were con-sidered, only moderately-significant correlation wasobserved in each mineral density. Therefore, selec-tion based on GCA is more warranted than selectionbased on SCA effect. There were significant recip-rocal effects on GMD traits, but those were not con-sidered important because the size of reciprocalmean square was relatively smaller than for GCAand SCA effects.

Parents and crosses selected by GCA and SCAeffects were mostly traditional rice varieties andtheir combinations require further breeding to com-


Table 4. Phenotypic correlations among grain mineral density of 71 crosses (F1 + RF1) of 9 × 9 diallelpopulation. IRRI, 1999.

Ca Cu Fe K Mg Mn P S

Cu 0.25*Fe 0.31** 0.66**K 0.13ns 0.51** 0.84**Mg 0.16ns 0.64** 0.94** 0.90**Mn 0.23ns 0.10ns 0.21ns 0.38** 0.20nsP 0.20ns 0.63** 0.94** 0.93** 0.99** 0.25*S 0.30* 0.58** 0.89** 0.77** 0.88** –.07ns 0.88**Zn 0.07ns 0.55** 0.89** 0.87** 0.93** 0.22ns 0.94** 0.86**

Table 5. Suggested ratio of general combiningability (GCA) to specific combining ability (SCA)determined by 2 MSGCA/(2 MSGCA+MSSCA) foreight minerals. IRRI, 1999.

Grain mineral GCA/SCA

Fe 0.92Zn 0.91Ca 0.97Cu 0.95Mn 0.97P 0.92S 0.87K 0.93

bine high GMD and agronomically important char-acteristics. Evidence of existing heterosis should beexploited and needs to characterize for GMD. Theheterosis and significant SCA in this diallel popula-tion indicates need for in-depth genetic analysis toinvestigate the possibility of releasing the existinglatent genetic variability by either epistasis or link-age for GMD. It is essential to understand the na-ture of GMD in rice grain so as to not upset the bio-logically important ratio of all grain minerals.

QTL underlying phosphorus deficiencytolerance in riceJ. Ni, G.B. Gregorio, P. Wu,29 G.V. Vergara, Z. Li,C. Quijano-Guerta, and G. Kirk

Phosphorus deficiency is a major limiting factor forrice production in highly weathered soils in manyparts of the world. In addition to the natural lowlevel of P of those soils, there is high P fixation inrice soils such as acid, acid sulfate, and alkalinesoils. Genotypic variation in P-deficiency tolerance

by rice has been extensively documented, and it ispossible to develop varieties with increased P defi-ciency tolerance.

A previous study used a recombinant inbred (RI)population for genetic mapping. The marker locilinked to a major quantitative trait locus (QTL) un-derlying P deficiency tolerance were identifiedbased on segregation of phenotypic parameters insolution culture. Because of the heterogeneity andcomplexity of soils, it is crucial to confirm the re-sult in soil culture before initiating MAS or map-based cloning programs.

Based on the results from the previous study, 42each of the tolerant and sensitive RI populationswere used in mapping P-deficiency tolerance QTLs.The RI lines were from the cross IR20/IR55178-3B-9-3, where IR20 is P-deficiency tolerant andIR55178-3B-9-3 is sensitive.

PHENOTYPIC PERFORMANCE TO P DEFICIENCY

The selected RI lines (RIL) were phenotyped fortolerance for P deficiency in a greenhouse pot ex-periment using soil collected from a P-deficientfield in Pangil, Laguna, Philippines (soil pH =4.7;Olsen P = 3 mg kg–1). The field had not received Pfertilizer for at least 30 years. The soil was air-dried,ground to pass a 2-mm sieve, and fertilized at eitherlow P level (0.01 g P2O5 kg soil–1) or medium Plevel (0.06 g P2O5 kg soil–1) with sufficient N (0.08g N kg soil–1) and K (0.06 g K2O kg soil–1) for allthe treatments. Four pregerminated seeds of eachRIL were sown in pots containing 6.5 kg soil witheither low P or medium P level. Sixteen plants ofeach parent were also sown in pots with two dif-ferent P levels.


At 2, 3, 4, 5, and 6 wk after sowing, the tillers ofeach plant were counted. At 42 d after sowing, theshoots of each plant were removed, oven-dried at65 °C for 3 d and weighed to determine shoot dryweight (SDW). The dry plant tissue was ground andanalyzed for P content. P uptake (PUP as mgplant–1) and P use efficiency (PUE as plant dryweight mg–1 of absorbed P) were calculated.

Relative values of the growth parameters (rela-tive parameter) were calculated. The parametersdetermined were relative tillering ability (RTA),relative shoot dry weight (RSDW), relative P uptake(RPUP), and relative P use efficiency (RPUE) (Ta-ble 6). IR20 had higher RTA and RSDW thanIR55178, a result consistent with earlier reports, in-dicating that IR20 was more tolerant of low-P stressthan IR55178.

Segregation among the 84 selective RILs forRTA and RSDW was observed and the distributionsof the parameters were normal after log-trans-formation. The population means of the parameterswere near the parental means. Transgressive varia-tions in all four parameters were observed. ForRSDW, about 18.9% of the 84 selective RILs had aRPUP higher than IR20, and 38.9% had lowerRPUP than IR55178. Correlation analysis amongRSDW and RTAs for the 84 RILs showed highlysignificant correlation among these relative para-meters.

AFLP-RFLP-SSLP MAP

Amplified fragment length polymorphism (AFLP)-restriction fragment length polymorphism (RFLP)genotyping and map construction of the RI popu-lation were done earlier. The parents were also sur-

Table 6. Means and standard deviation of relative tillering ability (RTA) and relative shoot dryweight (RSDW) for the parents and selected genotypes grown in soil culture. IRRI, 1999.

Parent Selective genotype

Parametera IR20 IR55178 Tolerant Sensitive Range

RSDW (%) 34.1±3.7 25.2±2.9 38.9± 7.8 14.5± 5.1 2.9–146.5RTA2w 45.8±4.8 32.5±1.5 66.4±25.9 53.6±19.5 30.8–116.7RTA3w 60.3±5.7 28.2±2.6 59.3±25.9 38.6±14.2 18.2–155.6RTA4w 47.5±5.5 23.6±3.3 44.9±18.4 27.7±10.8 10.8–130.0RTA5w 49.4±8.4 25.2±4.1 47.2±30.2 22.7±12.2 8.0–155.6RTA6w 51.6±7.3 33.1±4.7 49.0±30.4 21.9±10.5 8.3–160.0

aRSDW = relative shoot dry weight, RTA2w = relative tillering ability 2 wk after sowing, RTA3w = RTA 3 wk aftersowing, RTA4w = RTA 4 wk after sowing, RTA5w = RTA 5 wk after sowing, RTA6w = RTA 6 wk after sowing.

veyed for simple sequence length polymorphism(SSLP) and polymorphic markers were used for se-lected RILs. Using SSLP markers together with pre-vious AFLP and RFLP anchors, all other AFLPmarkers were assigned to the 12 linkage groups atLOD >3.0 based on their linking to the anchormarkers. The map distances were estimated by theKosambi function.

The parental survey revealed 27 polymorphicSSLP markers. All these SSLP markers weremapped to the expected location verifying the pre-vious AFLP-RFLP map. The 27 SSLP markers, 26RFLP markers, and 30 AFLP markers were used asanchor markers to generate the linkage map (Fig. 3).The linkage map had a total map length of 1830.1cM. The average interval size was 8.39 cM with thesmallest on chromosome 4 (2.96 cM) and largest onchromosome 7 (17.23 cM).

QTLs FOR P-DEFICIENCY TOLERANCE

Data for RTA, RSDW, RPUP, and RPUE were usedfor QTL analysis after being normalized by logtransformation. Single-marker locus analysis at aprobability of less than 0.005 for error I and inter-val mapping with LOD value >2.4 were used fordetecting marker loci associated with the variationsin the parameters measured and most likely positionof the gene loci. The mean comparisons amongmarker genotypes for each trait were conducted us-ing t-test analysis. The proportion of the phenotypicvariance explained by the marker loci linked toQTLs detected was provided by regression analysis.

The RSDW and RTAs were used for both single-marker analysis and interval mapping analysis (Ta-bles 7, 8). For RTA2w, only one QTL accounting


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P3M

9_7

P3M

1_6

OS

R33

E5M

6_5

P1M

4_3

P4M

10_3

E3M

7_10

E7M

6_2

E4M

3_12

P1M

5_3

P2M

8_3

E6M

1_4

E6M

1_5

P1M

4_4

P1M

1_4

P2M

2_3C

H

E7M

5_8

42.5

45.9

47.1

49.0

52.8

57.6

61.1

66.2

74.7

90.8

111.

011

6.2

118.

312

1.7

129.

414

0.4

143.

314

4.9

146.

614

6.6

149.

415

0.8

160.

9

37.7

25.70.0

cMM

arke

r

CH

RO

.10

(E3M

6-7,

E7M

6-4)

(P3M

5-1,

P3M

9-2

P4M

1-2,

P4M

1-3)

(P3M

1-4,

E1M

3-9)

(E

5M4-

1)

(P3M

6-5,

E5M

4-11

)

(P3M

10-4

)(P

3M6-

2)

Dis

t(cM

)M

arke

r

0.0

RZ

797

(E4M

6-6)

E4M

2_7

P1M

6_4C

H

P2M

4_8

P1M

5_2C

HP

3M2_

1P

3M2_

3

P2M

2_4C

H

E5M

4_12

RM

209

RM

21

P4M

8_2

13.9

21.1

35.1

35.1

47.7

54.5

65.8

85.1

91.8

106.

0

54.5

(P2M

1-4)

(P4M

4-3)

(P1M

7-1)

(E4M

3-16

,

E4M

3-17

)

(P3M

2-2

P3M

9-3)

(P1M

7-6)

(E4M

2-4,

E4M

6-1)

Dis

t(cM

)M

arke

r

0.0

128.

411

8.9

96.1

92.8

88.0

84.0

77.9

75.2

73.2

64.2

57.2

49.0

39.4

29.3

22.7

20.0

15.48.6

OS

R32

RG

9P

1M7_

7

P1M

9_2

E5M

6_3

P2M

9_2

E1M

5_7

P1M

4_2

P1M

7_12

RM

235

E7M

5_9

P2M

1_1

E1M

5_12

E3M

6_5

CD

O34

4R

G41

3R

Z26

1

RZ

76

E1M

5_9(R

G24

1)

CH

RO

.11

CH

RO

.12

(P2M

4-IC

H, E

5 M

4-7)

(P1M

7-9,

E3M

8-8)

(P1M

1-5C

H,E

4M2-

1)

(P1M

10-2

, E5

M6-

6)

(P1M

7-3,

P2

M9-

6)

E5M

4-7)

E5M

6-6)

P2M

9-6)


Table 7. Putative QTLs underlying tolerance for P stress detected using intervalmapping program based on relative parameters measured. IRRI, 1999.

Traita Marker Chromosome Additive % VARb LODc

effect

RSDW E3M8-3~ E1/M7-7 6 0.200 28.6 4.96OSR32~RG9 12 –0.228 36.4 6.97

RTA2w E3M8-3~ E1/M7-7 6 0.180 27.8 4.39RTA3w E3M8-3~ E1/M7-7 6 0.109 33.2 6.17

OSR32~ RG9 12 –0.121 40.0 7.45RTA4w E3M8-3~ E1/M7-7 6 0.115 28.0 5.12

OSR32~ RG9 12 –0.128 34.6 6.25RG413~CDO344 12 –0.086 15.9 2.83

RTA5w E3M8-3~ E1/M7-7 6 0.149 28.5 5.09OSR32~ RG9 12 –0.177 38.4 7.13

RTA6w E3M8-3~ E1/M7-7 6 0.151 31.7 5.65OSR32~ RG9 12 –0.193 50.1 10.11RG413~CDO344 12 –0.116 19.2 3.48

aRSDW = relative shoot dry weight, RTA2w = relative tillering ability 2 wk after sowing, RTA3w =RTA 3 wk after sowing, RTA4w = RTA 4 wk after sowing, RTA5w = RTA 5 wk after sowing, RTA6w= RTA 6 wk after sowing. bVariation contributed by single QTL across the population. cLODscores (log10-likelihood ratio).

Table 8. Mean comparisons for the relative parameters measured between genotypic classes of markerloci linked to QTLs detected. IRRI, 1999.

Genotype

Parametera Marker Chromosome IR20 IR55178 Peb Fc R+ Av.(%)d

RSDW E3M8-3 6 14.21 33.62 –19.41 10.99 0.133 –72.6E1/M7-7 6 15.53 36.79 –21.26 13.61 0.155 –79.6OSR32 12 36.27 16.69 19.58 9.40 0.107 73.3RG9 12 39.17 11.91 27.26 26.28 0.268 102.0

RTA2w E1/M7-7 6 50.67 70.99 –20.32 16.14 0.172 –34.1RTA3w E3M8-3 6 35.52 59.55 –24.03 23.74 0.253 –49.1

E1/M7-7 6 37.80 61.77 –23.97 26.14 0.262 –49.0OSR32 12 60.79 35.99 24.80 27.47 0.269 50.7RG9 12 60.47 36.90 23.57 24.22 0.246 48.2

RTA4w E3M8-3 6 25.70 44.13 –18.43 18.81 0.208 -50.9E1/M7-7 6 27.11 47.31 –20.2 24.70 0.248 -55.8

OSR32 12 45.49 26.42 19.07 20.65 0.212 52.7RG9 12 44.98 26.56 18.42 21.78 0.224 50.9RG413 12 40.71 27.52 13.19 8.98 0.104 36.4

RTA5w E3M8-3 6 21.46 44.82 –23.36 18.19 0.204 –66.9E1/M7-7 6 23.12 48.77 –25.65 22.70 0.234 –73.5OSR32 12 47.31 21.57 25.74 22.35 0.229 73.7RG9 12 45.89 22.27 23.62 20.33 0.214 67.6

RTA6w E3M8-3 6 21.99 45.29 –23.3 18.32 0.205 –65.8E1/M7-7 6 23.53 49.19 –25.66 22.81 0.235 –72.4

OSR32 12 48.36 21.24 27.12 24.52 0.246 76.7RG9 12 47.61 21.23 26.38 27.64 0.273 74.5RG413 12 39.95 23.35 16.60 8.83 0.103 46.9CDO344 12 43.74 26.06 17.68 9.42 0.112 49.9

aRSDW = relative shoot dry weight, RTA2w = relative tillering ability 2 wk after sowing, RTA3w = RTA 3 wk after sowing,RTA4w = RTA 4 wk after sowing, RTA5w = RTA 5 wk after sowing, RTA6w = RTA 6 wk after sowing. bPhenotypic effects.cThe F statistic as determined by the PROC GLM procedure of SAS. dCoefficient of determination, the percent ofphenotypic variation explained by individual markers as determined from the PROC GLM procedure of SAS.


Table 9. IRRI breeding lines from the flood-prone breeding program named as varieties in thePhilippines, 1999.

Breeding line Parentage PSB Localname name

IR65185-3B-8-3-2 CSR10/TCCP266-B-B-B-10-3-1 PSBRc84 SipocotIR65195-3B-13-2-3 IR10198-66-2/TCCP266-B-B-B-B-10-3-1 PSBRc86 MatnogIR52713-2B-8-2B-1-2 IR64//IR4630-22-2-5-1-3/IR9764-45-2-2 PSBRc88 Naga

for about 27.8% of the total variations was closelylinked to P3M8-3 and and E1/M7-7 on chromosome6. For RSDW and RTA3w~6w, two common QTLswere detected by using both single-marker analysisand interval mapping. First common QTL flankedby marker loci RG9 and OSR32 on chromosome 12,respectively, explained about 36.4% and 33.2–50.1% of the total variations across the 84 selectivelines for RSDW and RTA3w~6w. Second commonQTL accounting for about 28.6% and 28.0–33.2%of the total variations in RSDW and RTA3w~6wwere closely linked to E3/M8-3 and E1/M7-7 onchromosome 6. For RTA4w and RTA6w, anothercommon QTL flanked by marker loci RG413 andCDO344 on chromosome 12 was identified, and itexplained about 15.9–19.2% of total variation.

To investigate allelic information of the QTLsfor P-deficiency tolerance, mean comparisons wereperformed for the relative parameters betweengenotypic classes of IR20 and IR55178 at themarker loci linked to the detected QTLs. For mostof significant marker loci, the genotypic class of thetolerant parent, IR20, was superior to other markerclasses. However, the classes identified by the sen-sitive genotype, at E3/M8-3 and E1/M7-7 on chro-mosome 6, were superior to tolerant classes (Table8).

IRRI lines named as varietiesfor saline-prone areasG.B. Gregorio, D. Senadhira, R.O. Mendoza,J.P. Roxas, G.S. Khush, P.S. Bonilla,1

H.C. dela Cruz,1 and T.F. Padolina1

Three IRRI breeding lines—PSBRc 84, PSBRc 86,and PSBRc 88—from the flood-prone breeding pro-gram were named as varieties for saline-prone areasin the Philippines (Table 9). These varieties hadimproved tolerance for salinity, were early matur-ing, resistant to diseases, and had good grain quali-ties.

This brought the number of IRRI breeding linesnamed as varieties in saline-prone areas in the Phil-ippines to five. Two others were released in 1995.In addition, the Rice Varietal Improvement Groupof the Philippines identified another salt-tolerantline, IR58443-6B-10-3, for pre-release, multiplica-tion, and distribution to farmers in coastal areas.

Program outlook

The program will merge with the Rainfed LowlandEcosystem Program in 2000. Flood-prone ecosys-tem research will be combined under two projects—crop and resource management and breeding. Useof MAS techniques will continue in screening andin understanding abiotic stresses in flood-prone riceareas.

Research programsCross-ecosystems research

BIOTECHNOLOGY TO ACCELERATE RICEBREEDING AND BROADEN THE RICEGENEPOOL 78Construction of a genomewide physical map of rice

using the IR64 BAC library (PBGB) 78Molecular cloning of xa5 (PBGB) 79

Physical map position of xa5 80Identification of candidate cDNA clones 80

BLAST analysis of the terminal sequences of clonedmarkers from the genetic map of rice 81

Development and field evaluation of transgenic IR72,M.H. 63, and hybrid rice Shan You 63 with a Btgene for stem borer resistance (PBGB, EPP) 81

Evaluation of transgenic IR72 with Xa21 for bacterialblight resistance (PBGB, EPP) 83

Evaluation of transgenic rice with Xa gene for bacterialblight resistance (EPP, PBGB) 84

NARS development of elite lines through breeding andmarker-aided selection (EPP, PBGB) 85Philippines 85India 85Indonesia 86

EXPLOITING BIODIVERSITY FOR SUSTAINABLEPEST MANAGEMENT 86Rice blast management through varietal diversification

(EPP) 86Field variants of tungro (EPP) 87

BIOLOGICAL NITROGEN FIXATION 88Diazotrophic endophytic bacteria (SWS) 89Growth-promoting activities (SWS) 89Working group meeting 89

RICE—A WAY OF LIFE FOR THE NEXTGENERATION OF RICE FARMERS 89Using multisector partners to deliver IRRI rice

technology to rainfed rice farmers in northeasternThailand (SSD, AE, TC, CIAP) 901998-99 activities 90Lessons learned (1998-99) 91

Post-production systems research (AE) 91Philippine Post-production Research Consortium 91

Rice quality management (AE) 92

SOCIOECONOMIC STUDIES FOR TECHNOLOGYIMPACT, GENDER, AND POLICY ANALYSIS 92Production of improved rice varieties in South and

Southeast Asia (SS, PBGB, Biometrics) 93Production of varieties 93NARS uses of IRRI materials 93

Demand for specialty rices: implications for technologydevelopment (SS) 98Changing structure in food demand 98Policy implications 98

IMPLEMENTING ECOREGIONAL APPROACHESTO IMPROVE NATURAL RESOURCEMANAGEMENT IN ASIA 98Market integration, agricultural diversification and

erosion risk in northern Thailand (APPA, SS) 99Changes in cropping systems to reduce erosion

risk 99Erosion risk decrease 99

PROGRAM OUTLOOK 99


Cross-ecosystems research

Biotechnology to accelerate rice breedingand broaden the rice genepool

Biotechnology research at IRRI covers a broadspectrum of activities. Notable successes wereachieved throughout the spectrum during 1999. Atthe basic end, the development of a physical map forchromosomes 11 and 12 of rice passed the half-waypoint and terminal sequencing was conducted on350 cloned markers from the genetic map of rice. Atthe applied end of the spectrum, several transgenicplants, with enhanced resistance to bacterial blightor stem borers, were tested in China. Molecularbreeding through marker-aided selection wassuccessfully applied in several NARS laboratories.

Construction of a genomewide physical mapof rice using the IR64 BAC libraryA.C. Sanchez, B. Fu, J. Talag, R. Maghirang,C. Aquino, S. Yu, J. Domingo-Rey, J. Mendoza,L. Nguyen, D. Brar, G.S. Khush, and Z. Li

A physical map consists of a series of ordered, con-tiguous recombinant DNA clones spanning the en-tire genome. It is measured physically in terms ofthe number of base pairs in the DNA and is essen-tial for the analysis of genome structure. A physicalmap is also the first requirement for the isolationand characterization of agronomically importantgenes based on their map positions. Our objectiveis to use the IR64 bacterial artificial chromosome(BAC) library to construct a physical map of ricethat has overlapping BAC clones spanning all therice chromosomes and to facilitate more efficientcloning of important rice genes-quantitative traitloci (QTLs).

The Cross-Ecosystems Research Program is designedto develop knowledge and tools to solve problemsthat are common across rice-growing ecosystems. Theprogram is anticipatory and seeks to create newopportunities, in addition to research on currentproblems that can enhance ecosystem-based re-search.

The program includes six research projects thatspan the disciplines of biological science, naturalresource management, and anthropology and socio-economics. One focus of the program is to applyadvances in biological sciences to develop practicaltools to improve germplasm and pest management,and to explore opportunities in biological N2 fixation inrice.

The biotechnology project involves the applicationof molecular and genetic tools to assist plant breed-ing. The Asian Rice Biotechnology Network (ARBN)establishes close collaboration with national agricul-tural research systems (NARS) to develop elitebreeding lines that address local problems.

Systems analysis is used to delineate the bio-physical and socioeconomic factors affecting land useand resource allocation and their implications to riceproduction. Through the Systems Analysis andSimulations in Rice Production Systems (SysNet), weform partnerships with NARS to develop methodol-ogies and tools for improving land use planning at thenational level and below.

The program examines factors affecting technologyadoption and the mechanisms needed to acceleratetechnology transfer to improve the livelihood offarmers. The socioeconomic component is concernedwith how rice technologies can benefit farmers andwith its impact on socioeconomic equality andpoverty.

Cross-ecosystems research 79

The physical map was constructed in three steps.First, the BAC library was screened with anchor re-striction fragment length polymorphism (RFLP)and sequence-tagged site (STS) markers to establishanchor BAC islands across the genome. Second, theexpected gaps between anchor BAC contigs werefilled by random chromosome landing. In doing so,three-dimensional DNA pools prepared from thewhole library were amplified with large numbers ofrandom primers to generate random BAC islandsfor gap filling. Putative-positive clones identified byrandom primers were isolated and confirmed indi-vidually with the corresponding DNA markers. As-signment of these random BAC islands to indi-vidual chromosomes was simultaneously conductedby genetic mapping (randomly amplified polymor-phic DNA [RAPD] markers associated with BACclones were mapped to their corresponding chromo-somes using a recombinant inbred mapping popu-lation) and by hitting anchor BAC islands. In thethird step, BAC contigs were assembled from theBAC islands by HindIII fingerprinting.

A total of 453 RFLP and STS markers have beenused to screen the BAC library, establishing the an-chor BAC islands across the genome. On average,3.3 BAC clones were identified by each marker,agreeing with the size of the BAC library (3.28 ge-nome equivalents) although chromosomes 7–10have the least number of assigned BAC clones. Wealso screened the BAC library with 498 RAPDprimers. Of those, 262 RAPD primers identified614 BAC islands consisting of 1,600 clones.Eighty-nine of the 614 BAC islands were localizedto respective chromosomes by hitting clones of the

anchor BAC islands. Hence, a total of 546 islandsconsisting of more than 1,800 clones have been as-signed to the different chromosomes (Table 1).

Based on these results, the framework physicalmaps for chromosomes 11 and 12 were largely es-tablished. The physical map of chromosome 11 con-sisted of 93 anchor BAC islands and 34 randomBAC islands with a total of 438 clones. This physi-cal map is estimated to cover 50% of chromosome11. The primary physical map of chromosome 12was constructed with a total of 414 clones, whichwere assembled into 54 large contigs, giving an ap-proximate coverage of 52% of the whole chromo-some. Physical maps for several gene-rich regionson chromosomes 3, 4, 5, and 9 have also been con-structed. This physical map will be useful for map-based cloning of important rice genes-QTLs andhelp in understanding the genomic structures ofmany chromosomal regions.

Molecular cloning of xa5A.C. Sanchez, B. Fu, D. Yang, G.S. Khush, and Z. Li

The project goal is to clone a recessive gene, xa5,which confers resistance to bacterial blight (BB) bypositional cloning. Rice genes conferring resistanceto BB have been the targets of intensive investiga-tion of the host and bacterial pathogen relationshipsin plants. Two of these resistance genes, Xa21 andXa1, had been cloned. Xa21 was reportedly a trans-membrane protein containing extracellular leucine-rich-repeat (LRR) and a cytoplasmic kinase domainwhile Xa1 contains a nucleotide-binding site and anLRR. Unlike the dominant resistance genes such as

Table 1. Chromosomal distribution of anchor BAC islands. IRRI, 1999.

Chromo- RFLP STS RAPD SSR Total Total Clonessome markers markers markers markers markers clones marker–1

number (no.) (no.) (av no.)

1 20 16 7 43 122 2.8 2 12 12 8 32 78 2.8 3 46 7 7 60 162 2.7 4 51 11 2 64 133 2.1 5 16 14 6 36 140 3.9 6 15 12 9 36 101 2.8 7 4 9 2 15 56 3.7 8 13 8 – 21 40 1.9 9 12 8 5 25 76 3.010 6 5 4 15 43 2.911 68 13 34 12 127 438 3.812 74 5 5 12 96 414 4.8 Total 337 120 89 570 1803 3.3


Xa21 and Xa1, our target gene for cloning, xa5, isrecessive. This gene has been physically mappedand a single BAC clone carrying the gene identified.Information on the gene product of xa5 will help tofurther elucidate the molecular mechanisms behindspecific host-pathogen recognition in plants.

PHYSICAL MAP POSITION OF XA5

The xa5 gene has been mapped to the distal end ofthe short arm of chromosome 5, tightly linked tothree RFLP markers—RG556, RG207, and RZ390.We used these three tightly linked markers as aprobe to screen the IR64 BAC library by colonyhybridization. Through fingerprinting of the BACclones and chromosome walking, a physical map ofthe xa5 region of chromosome 5, consisting of 14BAC clones, was established. The integrated physi-cal and genetic map indicates that xa5 is probablyin the region between RG556 and RG207.

IDENTIFICATION OF CANDIDATE CDNA CLONES

To check if xa5 is expressed in the homozygous re-sistance plants and to identify the candidate cDNAclone, an expression library from an incompatibleBB strain (race 2, PXO 85)-induced mRNA ofIRBB5 plants were constructed into the pSPORT1(GIBCO BRL) vector. We dot-hybridized three

overlapping BAC clones (44B4, 9E8, and 28N22)with total RNA isolated from induced IR24 andIRBB5 and obtained a differential signal with 9E8and 28N22. The cDNA library was then screenedwith the BAC clones 9E8 and 28N22. The clone28N22 identified 14 cDNA clones while 9E8 hy-bridized to two clones. The common cDNA cloneidentified by both 28N22 and 9E8 was 5P2. Hy-bridization of 5P2 to the BAC clones revealed twostrong bands (8 and 4 kb) and a weak band (2 kb)on 28N22 and only the 2-kb band on 9E8(Fig. 1). Northern hybridization of 5P2 indicated a5-kb RNA band, suggesting that 5P2 appeared to beconstitutively expressed.

The clone 5P2 was sequenced, revealing a com-plete insert length of 1.7 of 5P2. Database search ofthe 5P2 sequence using BLAST 2.0 shows that agreat length (~1.5 kb) of the sequence is homolo-gous to a rice retrotransposon while the remaining200 bp has homology to some known kinases.Analysis using the GENESCAN program predictsa single peptide of 72 amino acids potentially en-coded in the initial 218 bp of the 5P2 sequence. ThePROSITE program identified five probable kinasedomains within the 72-amino-acid-long peptide.The 8-kb subclone from the BAC clone 9E8 is be-ing transformed into IRBB5 plants and sequencingof the whole 9E8 clone is in progress. We expect toclone xa5 in the near future.

1. Southern hybridization of BAC clones on the xa5 contig using 5P2 cDNA as probe.IRRI, 1999.


BLAST analysis of the terminal sequences ofcloned markers from the genetic map of riceS. Constantino, A. Resurreccion, B. Albano,J.A. Champoux, C. Villareal, G.S. Khush,and J. Bennett

Functional genomics seeks to assign biologicalfunction to the sequences of genes and intergenicregions. This assignment may be accomplished bya variety of approaches, including sequence compa-rison with known genes. We attempted to sequence350 of the markers of the rice genetic map that wasestablished principally at Cornell University. Thesedata supplement the large database assembled fromsequenced markers of the genetic map developed bythe Rice Genome Research Project, Tsukuba, Japan.Terminal sequencing was conducted principally onboth RZ clones (cDNA clones derived from RNAof etiolated leaves of IR36) and RG clones (ge-nomic clones derived from IR36 DNA). Some bar-ley (BCD) and oat (CDO) cDNA clones were alsosequenced. Both ends of each clone were sequencedto allow polymerase chain reaction (PCR)-basedamplification of longer DNA segments than is pos-sible with data derived from the single-passsequencing. The nucleotide sequences and the de-duced amino acid sequences of each terminus werethen compared with the Genbank databases usingprograms of the Basic Local Alignment Search Tool(BLAST). Table 2 shows hits with the BLAST-Nprogram accessed through the Entrez Web site atwww.ncbi.nlm.nih.gov.

A total of 76 mapped clones, representing all 12chromosomes of rice, recorded hits on known se-quences. The termini of each clone were designatedas F or R, depending on whether they weresequenced using the universal forward (F) or re-verse (R) sequencing primer. As all inserts had beenspliced into the vectors in random orientation, therewas no relationship between the F and R ends andthe direction of transcription of the gene. Most ofthe hits (71%) were among the RZ clones, consist-ent with these clones being from a cDNA library.Relatively few hits (24%) were found among theRG clones, which were random PstI genomicclones. The remaining hits (5%) were BCD andCDO cDNA clones. In 20% of the 76 clones regis-tering hits, both termini hit on known genes, and inall of these cases, the same class of protein was re-

vealed, even if the name was different, as in the caseof RZ244. For the remaining 80% of clones, onlythe F or R terminus hit on a known gene. The usualreason for the lack of homology at the other termi-nus was that the terminus corresponded to a poorlyconserved region of the gene such as the 3’-untranslated region.

This research was supported in part by grantsfrom the Rockefeller Foundation and the GermanFederal Ministry for Economic Cooperation andDevelopment (BMZ).

Development and field evaluation oftransgenic IR72, M.H. 63, and hybrid riceShan You 63 with a Bt gene for stem borerresistanceS.K. Datta, K. Datta, J. Tu, G.S. Khush,Q. Zhang,30 G.Y. Ye,29 M. Cohen, and Y.L. Fan19

The plasmid pFHBT1, which contains a hybrid Bttoxin gene made from synthetic cryIA(b) andcryIA(c) under control of rice ActinI promoter withits first intron, was used for rice transformation inthis study. The recipient genomes included eliteindica rice IR72 and Chinese cytoplasmic male ster-ile (CMS) restorer line Minghui 63 (M.H. 63). Bothcultivars are restorer lines that have been used inrice production for more than a decade and are stillconsidered among the best for their yield potentialand combining ability.

Rice transformation was done by the biolisticmethod. The transgenic plants obtained were evalu-ated on the different criteria such as DNA integra-tion, protein production, and phenotypic acceptabil-ity. Homozygous transgenic lines were then evalu-ated in field plots in collaboration with HuazhongAgricultural University and Zhejiang University,China. The target insects included yellow stemborer, striped stem borer, and leaffolder.

Molecular analysis and bioassay demonstratedthat the hybrid Bt toxin gene made from the syn-thetic cryIA(b) and cryIA(c) was successfully inte-grated and expressed in the genome of both IR72and M.H. 63. The typical expression levels of Bt-endotoxin detected in both rices was estimated to be0.01–0.2% of the total soluble protein in leaf tissueor stem tissue. The bioassay results showed that lar-val mortality after feeding on cutting stems for 4 dreached 100% on all tested Bt-expressing plants.


Tabl

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The data from the field trial confirmed that sea-son-long protection from heavy infestation of Lepi-doptera insects was obtained in both IR72 and M.H.63 transgenic lines as well as the M.H. 63-producedrice hybrid (Fig. 2). This protection was achievedwithout affecting the combining ability of originalrestorer line M.H. 63 and its resultant hybrid ShanYou 63. Twenty-eight percent yield advantage wasrecorded using Bt hybrid rice when compared withnon-Bt hybrid rice.

Evaluation of transgenic IR72 with Xa21for bacterial blight resistanceS. K. Datta, J. Tu, K. Datta, G.S. Khush,Q. Zhang,30 and T.W. Mew

Gene Xa21 is known to confer resistance to mostknown bacterial blight (BB) races in India and thePhilippines. We introduced Xa21 into the genomeof IR72 via the biolistic method. The transformantobtained was designated as TT103. Molecularanalysis of T0 and T1 plants of TT103 demonstratedthat the intact coding sequence of Xa21 is presentin the recipient genome, without rearrangement, andthe inheritance of the transgene in the T1 generationfits the one-locus integration pattern. The T1 plantspositive for the transgene proved to be highly resist-ant to prevalent races 4 and 6 of Xoo.

Based on the characterization of resistancephenotype and molecular analysis, several homo-zygous lines carrying Xa21 were obtained from thetransformed IR72. The homozygous line, TT103-10, with the best phenotype and seed-setting was

2. Pest reaction of transgenic line T51-1 (right) and non-transgenic Minghui 63 control plants (left) to a heavy infestationof yellow stem borer. IRRI, 1999.


repeatedly tested in the field in Wuhan, China, in1998 and 1999 to evaluate its levels of resistance toBB.

The races of Xoo used in the experiments wereisolated from the Philippines, Japan, and China. Theresults demonstrated that the transgenic homo-zygous line expressed the same resistance spectrum,but with a shorter lesion length, to each inoculatedrace as Xa21 donor line IRBB21 (Table 3).Nontransformed control IR72 carrying Xa4 was re-sistant to Philippine races 1 and 5, Chinese race 4,and Japanese race 2 but susceptible to Philippineraces 6 and 3. Negative control variety IR24 wassusceptible to all races.

The Xa21 transgene led to excellent field per-formance of the induced-BB resistance trait on therecipient plants. The yield performance of thetransgenic homozygous line TT103-10 is com-parable with that of IR72 in field plots.

Table 3. Resistance performance of transgenic homozygous line, TT103-10,against multiple races of Xoo in field trials at Huazhong Agricultural University,Wuhan, China, 1999.

Plants tested Lesion lengthXoo race Variety (no.) (cm) Performancea

Philippine race 1 IR72 90 1.04 ± 0.12 R (PXO 61) TT103 90 0.31 ± 0.05 HR

IR24 90 16.43 ± 1.32 HSIRBB21 90 0.97 ± 0.24 HR

Philippine race 3 IR72 90 9.00 ± 0.86 S (PXO 79) TT103 90 0.61 ± 0.24 HR

IR24 90 14.11 ± 1.46 HSIRBB21 90 0.82 ± 0.40 HR

Philippine race 6 IR72 90 9.37 ± 1.21 S (PX O99) TT103 90 2.43 ± 0.53 R

IR24 90 15.69 ± 1.24 HSIRBB21 90 8.00 ± 1.20 S

Philippine race 5 IR72 90 0.72 ± 0.13 HR (PXO 112) TT103 90 0.39 ± 0.09 HR

IR24 90 7.60 ± 1.11 SIRBB21 90 1.02 ± 0.62 R

Chinese race 4 IR72 90 1.41 ± 0.53 R (Zhe 173) TT103 90 0.79 ± 0.31 HR

IR24 90 11.16 ± 1.89 SIRBB21 90 1.58 ± 0.73 R

Japanese race 2 IR72 60 0.71 ± 0.45 HR (T2) TT103 60 0.61 ± 0.31 HR

IR24 60 20.01 ± 1.89 HSIRBB21 60 1.94 ± 0.91 R

aR = resistant, S = susceptible, HS = highly susceptible, MS = moderately susceptible, HR =highly resistant.

Evaluation of transgenic rice with Xa genefor bacterial blight resistanceT.W. Mew, S.K. Datta, A. Ona, and C.M. Vera Cruz

A microplot experiment was done on the basis of aprotocol approved by the National Biosafety Com-mittee of the Philippines. The Xa21 gene in thetransgenic line TT103 significantly reduced BB in-fection. Transgenic rice had a slow rate (r) of dis-ease increment (r = 0.11, 0.07, and 0.17 caused re-spectively by races, 1, 3, and 6) when comparedwith nontransformed IR72 (r = 0.41, 0.41, and0.51).

Five rows of purple rice (recessive gene for pur-ple color and highly susceptible to BB) were grownaround each plot to determine the gene flow fromtransgenic to nontargeted rice. A pathogenicity testof purple rice grown from seeds of the first row(closest to transgenic plants) showed that all plantsremained purple and were highly susceptible to BB,suggesting no evidence of gene flow in screenhousetests.


NARS development of elite lines throughbreeding and marker-aided selectionH. Leung, D. Brar, C.M. Vera Cruz, L. Sebastian,1

R. Tabien,1 D. Tabanao,1 S. Singh,14 M. Sodhi,14

G.S. Mangat,14 Y. Vikal,14 M. Bustamam,15

Suwarno,15 E. Lubis,15 A. Warsun,15

S. Christiyanthy,15 D. Agisimanto,15

and T. Kadir15

Current research in the Philippines, Indonesia, andIndia has focused on pyramiding genes for BB re-sistance to improve local commercial cultivars be-fore release to farmers (Table 4).

PHILIPPINES

Molecular markers associated with xa5, Xa21, andthe gene from Oryza minuta were used by the Phil-ippine Rice Research Institute (PhilRice) inpyramiding genes for BB resistance in PSBRc 14,BPI Ri-10 and IR64. The markers were used in theinitial plant selection during three backcrosses madein the three recurrent parents. Lines from six crosseswere evaluated at three different stages of breeding,and the homogeneous lines were included in twoyield trials.

In a nonreplicated yield trial, 10 of 30 lines wereas good as, or better than, the check PSBRc 28. The

Table 4. Elite lines carrying one, or a combination of, bacterial blight resistance genes developed by NARS institutesthrough marker-aided selection into popular commercial cultivars, 1998–99.

Yield(t ha–1)a

NARS Cross combination Generation Genes1999 DS 1999 WS

Philippines BPI Ri-10 3*/IRBB5-21 BC3F6 (4 lines) xa5, Xa21 6.2–7.2 4.3–5.7BPI Ri-10 3*/IR59183 BC3F6 (4 lines) O. minuta gene 7.1–7.8 3.9–5.1PSBRc 14 3*/IRBB5-21 BC3F6 (1 line) xa5, Xa21 7.0 4.0IR64//IR59183/PSBRc 14 BC3F6 (1 line) O. minuta gene 7.9 5.0IR72 (control) – Xa4 6.2 4.6PSBRc 28 (control) – – 5.9 4.4

India PR106 3*/NH56 BC3F3 xa5 – –PR106 3*/NH56 BC3F3 xa13 – –PR106 3*/NH56 BC3F3 Xa21 – –PR106 3*/NH56 BC3F3 xa5 + xa13 – –PR106 3*/NH56 BC3F3 xa5 + Xa21 – –PR106 3*/NH56 BC3F3 xa13 + Xa21 – –PR106 3*/NH56 BC3F3 xa5 +xa13 + Xa21 – –

Indonesia Bio9-Mr-V-V/4-8-Pn-1 BC5F5 Xa7 – –Bio9-Mr-V/4-5-Kn-5-1 BC5F5 Xa7 – –Bio10-Mr-V1/1-1-Pn-1-1 BC6F4 xa5 – –Bio8-Mr-V/3-4/Pn-3-1 BC5F5 xa5 – –

a– = no data available.

highest yield of 4.9 t ha–1 was obtained from AR32-2-82-6, a progeny of IR64//IRBB5-21/PSBRc 14.In a wet-season (WS) replicated yield trial, 10 elitelines yielding 4-5 t ha–1 performed well despite highdisease and insect pressure (Table 4). Crosses aimedto combine the three genes (xa5, Xa21, and genefrom O. minuta) into PSBRc 14, IR64, and BPI-Ri-10 were made and will be advanced in 2000 dry sea-son (DS).

INDIA

A cross was made at Punjab Agricultural University(PAU) between local commercial cultivar PR106and pyramid line NH56 carrying xa5, xa13, andXa21. BC3F3 lines were developed from this crossby subsequent backcrossing with PR106. Three se-quence-tagged site (STS) markers corresponding toxa5, xa13, and Xa21 were used to pyramid the genesinto PR106. A combination of two or more geneswas more effective in providing resistance to Pun-jab and Philippine BB strains than the individualgenes. A PR106 pyramid line carryingxa5+xa13+Xa21 genes showed a high level of re-sistance to BB strains from both countries.

BC3F3 lines of PR106 carrying individual genesand their combinations were evaluated at 31 farm-ers’ fields in Punjab for resistance to the predo-


minant field population of BB. Replicated yield tri-als of the BC3F3 pyramided lines are in progress atPAU. BC4F1 of PR106/PR106 (xa5+xa13+ Xa21)were planted in the field to advance gene pyramidswith xa5, xa13, and Xa21.

INDONESIA

The genes xa5, Xa7, and Xa21 were respectivelyintrogressed singly in IR64 from the IR24 near-isogenic lines, IRBB5, IRBB7, and IRBB21. Thesegenes were effective against the predominantpopulation of BB pathogen in Indonesia. STS prim-ers for xa5 and Xa21, and G1091 probe for Xa7were used in selecting and confirming linesintrogressed with the genes (Table 4). Field andgreenhouse evaluation of the lines for resistance todiagnostic strains at Sukamandi Rice Research In-stitute and IRRI showed a high level of resistancewhen compared with the donor cultivars. Bio-xa5,the IR64 line carrying xa5, showed higher resist-ance to the diagnostic strain in the Philippines thanto the donor cultivar due to quantitative comple-mentation of xa5 from IRBB5 and Xa4 in the recur-rent parent IR64. Both Bio-xa5 and Bio-Xa7 (IR64line carrying Xa7 gene) are currently at BC5F5 gen-eration and are comparable with IR64 in agronomiccharacters such as height, maturity, tillering ability,and amylose content, but are more resistant to BB.Lines carrying either xa5 or Xa7 have been selectedby STS marker and DNA probe for seed purity formultilocation tests at different collaborating institu-tions and in farmers’ fields.

Selected breeding lines of Bio-xa5+Xa7 andBio-Xa21 are being evaluated for their resistance tothe diagnostic BB strains in Indonesia. Incor-poration of tungro resistance into Bio-xa5+Xa7 iscurrently under way.

Exploiting biodiversity for sustainablerice pest management

Rice pest management can be made more effectiveand sustainable by increasing biodiversity at thegenetic, species, and community levels.

Rice blast managementthrough varietal diversificationZhu Youyong,16 Chen Hairu,16 Fan Jinghua,16

Wang Yunyue,16 Li Yan,16 Fan Jinxiang,16

Yang Shisheng,16 Wang Zonghua, C. Mundt,T. Mew, and H. Leung

Increasing the genetic diversity of crop populationsthrough deployment of multilines or mixture of va-rieties has been successfully used to manage cerealdiseases, such as stripe rust of wheat and powderymildew of barley. An Asian Development Bank-funded project, Exploiting Biodiversity for Sustain-able Rice Pest Management, supported collabora-tive research by Yunnan Agricultural Universityand IRRI to diversify varieties in farmers’ field as ameans to control blast.

On-farm field trials started in 1997 found thatinterplanting glutinous varieties (Huangkenuo orZinuo) with indica hybrid varieties (Xianyou 63 orXianyou 22) significantly reduced the incidence andseverity of rice blast. The field design was a repeat-ing pattern of one row of glutinous rice interplantedwith four or six rows of indica rice. Interplantingjaponica varieties Hexi 41, Chujing 12, and Luxuan1 did not result in disease reduction.

Farmers in Yunnan adopted interplanting on 812ha in 1998 and 3,342 ha in 1999. Yield and diseasedata obtained in 1999 from 15 demonstration fieldsat five sites in Jiangsui county are in Table 5. Dis-ease incidence and severity were lower for varietiesused when grown in mixture than when grown inpure stand. Reductions were remarkable in gluti-nous varieties Zinuo and Huangkenuo where con-trol efficiency ranged from 83.8 to 96.5%. Totalyield in mixtures was 0.8–0.9 t ha–1 higher than withyield of pure indica rice.

The effectiveness of interplanting to control blastseemed to be associated with the functional diver-sity of the component varieties. DNA fingerprintsgenerated by polymerase chain reaction (PCR)primers corresponding to the conserved motifs ofdisease resistance genes, reveal a high degree ofgenetic polymorphism between the glutinous andthe indica varieties but not among the japonica va-rieties used. The genetic relationships among thevarieties interplanted are depicted in the dendro-gram shown in Figure 3. Data from studies at IRRIalso indicate that the polymorphism revealed by re-


Table 5. Performance of varieties in mixture and pure stands during the 1999cropping season in Jianshui County, Yunnan Province, China.

Blast Disease Yield of Combined YieldTreatment Variety severity control components yield increase

index (%) (t ha–1) (t ha–1) (t ha–1)

Mixture Xianyou 63/ 1.16 69.1 9.6 10.5 0.86 Huangkenuo 1.65 95.4 0.9

Mixture Xianyou 63/ 1.57 58.1 9.6 10.5 0.8 Zinuo 1.83 85.3 0.8

Mixture Xianyou 22/ 2.24 50.7 9.1 10.0 0.9 Huangkenuo 1.25 96.5 0.9

Mixture Xianyou 22/ 2.28 49.8 9.1 10.0 0.9 Zinuo 2.01 83.8 0.9

Pure Xianyou 63 3.75 9.7Pure Xianyou 22 4.55 9.1Pure Huangkenuo 36.19 5.1Pure Zinuo 12.45 4.9

sistance gene analogs (RGA markers) correlateswith the diversity in resistance to blast and is poten-tially useful as predictor of functional diversity forblast resistance.

The mechanisms by which interplanting diversevarieties reduces blast disease may involve physi-cal obstruction to the spread of inoculum on sus-ceptible plant, inoculum density reduction, micro-climate change, and induced resistance as a resultof incompatible interaction. PCR fingerprints ofblast isolates obtained from mixture and mono-culture fields showed that mixtures tend to supportdiverse blast pathogen populations with no singledominant strain. However, pathogen populations inmonoculture fields tended to be dominated by oneor few dominant strains.

The interplanting approach presented an oppor-tunity for Yunnan farmers to successfully grow glu-tinous varieties, which are highly valued but sus-ceptible to blast, without high inputs of fungicide.The gain in yield and reduction in fungicide usetranslated to about US$189 ha–1 improvement infarmers’ income during 1999. Interplantig is ex-pected to extend to more than 100,000 ha by 2002.

Field variants of tungroO. Azzam, K. Umadhay, F. Sta Cruz,and K. McNally

The heterogeneity of field populations of both ricetungro bacilliform virus (RTBV) and rice tungrospherical virus (RTSV) was previously establishedusing genetic markers. However, to examine theextent of sequence variability and the possible evo-lutionary relatedness among the different tungroisolates, an RTBV genome region (nt 7747-289),which includes the intergenic region and part of theopen reading frame I, was amplified from nine dif-ferent isolates and sequenced directly. In addition,the RTSV coat protein region 2 (nt 3070-3607) wasamplified from 24 different isolates and sequenceddirectly.

Three RTBV isolates from the Philippines, threefrom Vietnam, and two from Indonesia were exam-ined. The published sequence of Serdang, aMalaysian isolate, was also included as a check. ForRTSV, 13 isolates from Indonesia and eight fromthe Philippines were examined. The published se-quence of two more isolates from the Philippinesand one from Malaysia was included.

3. Dendrogram constructed using RGA profiles generated withthe PCR primers XLRR, Pto kinase, and NLRR for varieties usedin interplanting trials. Variety 8126 is a sister line of Luxuan 1,the japonica variety used in interplanting experiments and isgenetically similar to Hexi 41 and Chujing 12. Jianshui County,Yunnan Province, China, 1999.

Xianyou 63

Xianyou 22

Zhinuo

Huangkenuo

Hexi 41

Chujing 12

8126

0.45 0.56 0.67 0.79 0.90Coefficient


Sequence alignment and phylogenetic groupingwere attempted on the sequences with the neighbor-joining, parsimony, and maximum likelihoodmethod of quartets. Sequence alignment was per-formed using CLUSTALW. Phylogenetic recon-struction by neighbor-joining and parsimony meth-ods was conducted with programs from PHYLIP3.5c, whereas the maximum likelihood analysis wasaccomplished by the quartet puzzling method ofPUZZLE 4.0. Graphics of the trees were drawn us-ing TREEVIEW 1.5.

Phylogenetic analysis of RTBV sequences showthree well-defined groups. The first group clusteredthe isolates from the Philippines, the second clusterhad the Vietnamese isolates, and the third group theIndonesian isolates. The Malaysian isolate ofSerdang, which was included as a check, did notcluster with any of the three groups. Bootstrap val-ues for the parsimony analysis indicated that thesethree major groups were respectively observed inmore than 70%, 54%, and 92% of the 1,000 treesdetermined.

Phylogenetic analysis of RTSV coat protein re-gion 2 sequences also showed three major lineages(Fig. 4). Most of the Indonesian isolates clustered inthe first lineage with high significances found forthe nodes in the bootstrap analysis of the puzzle tree(74%). The other two lineages also had highsignificances for nodes clustering mostly the Phil-ippines isolates (47% and 88%).

These results confirm the geographical distribu-tion of both RTBV and RTSV populations but showa less discrete distribution because two RTSV Indo-nesian and Philippine isolates cluster in one lineageof RTSV puzzle 2 tree. Migration or gene flowseems to occur between some RTSV populations,while location-specific isolates were detected aswell. The geographic isolation of tungro popula-tions has implications for the deployment of tungroresistance. Disease outbreaks may be localized andthe appearance of resistance-breaking strains in onegeographic location may not mean that they willeasily spread to other locations. Therefore, targeteddeployment of relevant resistance genes to a par-ticular environment may be effective.

4. Puzzle tree for nucleotide sequence alignments for coat protein2 of 24 RTSV isolates. The numbers above an internal branchare percentages of times a grouping occurred in 500 bootstrapreplicates of the data. Isolate name includes the country (I forIndonesia and P for Philippines), the province (Ib for Bali or Isfor Subang or Pc for North Cotabato, Pe for Nueva Ecija, Pg forIRRI-Philippines greenhouse isolates), the isolate field number,if any, and the coat protein genotype of that isolate. The barindicates the branch length corresponding to a maximumlikelihood distance of 0.01. IRRI, 1999.

Is76IVIb60M

Ib121

Ib22VIII

Is72M

9760

744732

23 Is75VIIIIs73M

Is85M6.819

Ib36V5293

5776

Ib52VIb01VIs81V

PgA

Pg08V

Pc03Vl

Pg09VlPgVt6lll

Pc17lll

P71lllM70lll

Pc34llb42ll

Pc41llPe21ll

43

64

88

41

47

100

5.2

0.01

9449

90

75

Biological nitrogen fixation

J.K. Ladha, P.M. Reddy, P. Gyaneshwar,32

N. Mathan,33 S. Peng, B. Reinhold-Hurek,34

W.L. Barraquio,35 A.K. Tripathi,36 A. Kumar,36

F.B. Dazzo,37 B.G. Rolfe,38 and Y.G. Yanni39

The strategies for developing endophytic/symbioticnitrogen fixation in rice include the establishmentof effective endophytic associations and thedevelopment of legume-like nodulation.


Diazotrophic endophytic bacteriaPredominant diazotrophic endophytic bacteria wereisolated from surface-sterilized roots and stems aswell as seeds of several rice varieties grown innonsterile soil. Most abundant stem- and rootbornediazotrophs were identified by 16S rDNAsequencing and SDS-PAGE analysis. A dominantendophyte identified as Serratia marcescens repre-sents a novel diazotroph and seems to possess alter-nate nitrogenase. The seedborne endophytes weregrouped by fingerprinting using PCR with BOXprimers. Some of these promising endophytes werefurther characterized by whole cell protein analysisand 16S rDNA sequencing, and identified as speciesbelonging to Alcaligenes, Rhizobium, and Kleb-siella.

Several endophytes, including seedborne bacte-ria, showed the ability to systemically spread tovarious rice plant parts during plant growth. Seedtransmission as an important mechanism of endo-phytic establishment has an advantage in the devel-opment of seed-based bacterial inocula.

A novel DNA-based detection method to tagbacteria by using signature sequence for monitoringin field was developed. The detection method willallow the verification of the abundance of the inocu-lated bacterial strains in rice tissues and soils fromvarious agroecosystems.

Growth-promoting activitiesSix diazotrophs from a wide host range were in-vestigated to determine their growth-promoting ac-tivities in the lowland rice cultivar Pankaj. Ino-culation with Rhizobium leguminosarum bv. trifoliiE11, Rhizobium sp. IRBG74, and Bradyrhizobiumsp. IRBG271 respectively increased grain and strawyields by 8–22% and 4–19%. Nitrogen, P, and Kuptake were increased by 10–28% due to rhizobialinoculation. Iron uptake increased by 15–64% atdifferent N rates. Inoculated diazotrophs producedabout 2 mg L–1 indole-3-acetic acid in rice root exu-date. It is likely that the increases in rice growth andnutrient uptake were due to growth-stimulating sub-stances produced by rhizobia.

Inoculation with Rhizobium sp. IRBG74 signi-ficantly and consistently promoted the single-leafnet photosynthetic rates in rice with different Ntreatments.

Working group meetingThe third biological N2 fixation working groupmeeting was held at IRRI. Twenty-four researchpapers covering a wide range of topics on rice-en-dophyte and rice-rhizobial interactions and nif genetransfer were presented. The working group formu-lated future directions for research and recom-mended the inclusion of studies on rice-mycorrhizalassociations as part of the program to understand thegenetic predisposition of rice to form symbiotic as-sociations.

A project review by a panel of external expertswas conducted during the working group meeting.The panel recommended

● assessment of N2 fixation and plant growthpromotion by endophytic diazotrophs in thelaboratory, greenhouse, and field;

● initiation of studies on rice-mycorrhizalassociations with an aim to identify symbioticgenes common between legumes and rice, andfunctional genomics to characterizesymbiosis-related genes in rice;

● investigations to incorporate N2 fixation (nif)genes into rice; and

● establishment of international steering com-mittees to function as advisory bodies to helpidentify appropriate research on biological N2fixation in rice.

Rice, a way of life for the next generationof rice farmers

This research acknowledges the growing knowl-edge gap between researchers and farming commu-nities and seeks to bridge that gap. This is donethrough identifying and fostering partnerships withcommunity development and extension organiza-tions including nongovernment organizations(NGO), the private sector, farming organizations,and kinship networks. The main objectives are:

● Improve rural incomes and reduce drudgery inrice farming through the introduction of appro-priate engineering and knowledge-intensivecrop management systems.

● Understand the social, economic, and techni-cal factors that influence knowledge acqui-sition and absorption, and develop commu-nication mechanisms for faster adoption oftechnologies.


Using multisector partners to deliverIRRI rice technology to rainfed ricefarmers in northeastern ThailandC. Edmonds, M.A. Bell, R. Raab, S. Morin,and J. Rickman

Thailand’s Population and Community Develop-ment Association (PDA), Department of Agri-culture (DOA), and IRRI are principal partners in aproject in a rainfed area of Buriram Province. Theobjective is to improve understanding of institu-tional arrangements to enhance rural livelihoods.The project includes participation in and researchabout nontraditional partnerships in technology de-velopment and local adaptation. The participatingorganizations form a unit in which the DOA assistsIRRI with the diagnostic and technical phase, andthe PDA delivers the technology to farmer groupsthrough existing community networks.

Alhough PDA’s services were focused on urbanareas, it identified a need to set up programs in ruralareas to improve the earnings of rural householdsand thereby preempt the migration of families tourban areas. PDA established community-based in-tegrated rural development (CBIRD) centers in sev-eral towns throughout Thailand. A key componentof the centers involves hosting of small private sec-tor manufacturing facilities. The centers providerelatively high-paying manufacturing jobs to ruralworkers—often the children of farming families—without requiring the families to leave the country-side. PDA’s interest in increasing the agriculturalincome of rural families where rice is an importantcrop led to the development of the multisector part-ners’ project.

1998-99 ACTIVITIES

Project development involved IRRI scientists ac-companying PDA and DOA staff members to meetwith farmers. A series of problems were collectivelyidentified (water stress, nutrient and weed manage-ment, blast, and timeliness of input availability)along with technological options that interested thefarmers and appeared to offer potential to increasefarm welfare.

Work in 1998 involved families in two localitiesaround Nan Rong and Lam Plaimat. Demonstration

plots were established on each participating farmand a combination of interventions (including landleveling, integrated weed management, improvednutrient management, and a new blast managementtechnology) were applied. Early in the implemen-tation of the project, a need for greater input in fieldtechnical support became evident and the activeparticipation of DOA increased.

PDA field staff and a few participating farmerswere trained in the fundamentals of rice cultivation.Project field staff were provided with additionaltraining and technical backstopping by IRRI andThai DOA scientists. Training materials included aCD ROM-based rice pest compendium and instruc-tional materials on proper rainfed rice crop manage-ment. Farmer field days just prior to harvest pro-vided scientists and project staff members an oppor-tunity to discuss the technologies and issues of con-cern with local farmers. The field days highlightedsubstantial farmer interest and identified additionalproblems of seed health and grain quality.

The demonstration plots during 1998 had aver-age yield increases of more than 840 kg ha–1—or45% higher than average yields reported by farmsfor 1995-97. The average yield increase on the dem-onstration plots across all farms for 1998 was 83 kgha–1, a 25% increase. The yield increases variedacross technologies applied and participating farms.

Additional collaborators from the private sectorjoined the project in 1999. Word-of-mouth regard-ing results from the initial year, farmer field days,and advertising at the PDA-CBIRD centers substan-tially increased the number of farmers participatingin the project. The interest of local private-sectorfirms in collaborating with the project increased aswell. A number of political conflicts unfortunatelyemerged and required the attention of project lead-ers from the various organizations. The conflictsslowed progress for the project. In addition, earlyrains hampered land leveling, the most promising ofthe technological interventions tried.

Despite setbacks, more than 100 farmers fromthe same two localities participated in 1998. KrungThai Bank joined the project as a partner in 1999and initiated a rice seed cultivation component.DOA training on nutrient and weed managementand seed health continued.


Table 6. Issues and lessons learned during 1998-99 inprojects in Bangladesh and Thailand aimed at on-farmidentification and evaluation of technology and knowledgedelivery in partnership arrangements.

Issue Lessons learned

Stability ● It is vital that all partners have organi-zational stability (including financial,personnel, and institutional stability).Projects in Bangladesh and Thailandwere slowed because of changes inkey NGO staff.

Money ● Good programs and powerful partner-ships will fail without the financial re-sources for program activities. Pro-grams require adequate resources tocarry out activities and pay staff.

● An additional potential benefit ofmultisector partnerships may be anincrease in the public profile of pro-grams to assist the rural poor. Thiscan help to build a coalition of supportfor these issues, therefore assistingfund-raising efforts.

Institutional ● In implementing partnerships, it iscommitment important that project leaders talk to

the leaders from each participating or-ganization and ensure buy-in at thetop, middle, and bottom.

● Fostering trust and commitment to thestated goals of the partnership is es-sential. It should be recognized at theoutset that it takes time and sharedexperiences in working together tobuild trust and establish the confi-dence that each partner has the goodof the project and each other at heart.

● Individual self-interest or egos canoverride any institutional commitmentto partnerships.

Project driver ● An individual or individuals (preferablyon-site) from one of the organizationsmust assume a leadership role in theproject. This person, or persons,should coordinate project activities,control quality, and ensure that dead-lines and project commitments aremet on time.

Transaction ● There are considerable transactioncosts costs involved in establishing and

maintaining working relationships.Time is required for project staff toestablish a certain level of trustthrough meetings and project imple-mentation.

Private and ● Expect differences in the organi-public sector zational cultures of partners. This canperspectives lead to misunderstandings and mis-

communications in the early stages ofthe project.

LESSONS LEARNED (1998-99)

A number of issues emerged and lessons werelearned through pilot projects in Bangladesh andThailand. Those are summarized in Table 6.

Post-production systems research

PHILIPPINE POST-PRODUCTION RESEARCH

CONSORTIUM

R. Bakker, D.B. de Padua, and M.A. Bell

IRRI signed a memorandum of agreement in June1999 with the four main Philippine agencies in-volved in rice post-production research—the Na-tional Food Authority (NFA), the Bureau ofPostharvest Research and Extension, the College ofEngineering and Agrotechnology of the Universityof the Philippines Los Baños, and PhilRice—toform a research consortium. The objective is a com-prehensive approach in rice post-production re-search, better communication of results, and an in-crease in the participation of technology end-users.

Consortium staff members visited rice farmers,cooperatives, rice processing centers, and govern-ment grain handling facilities to identify problemsand prioritize research activities. Case studies ofsuccessful and failed technology introductions de-fined an appropriate dissemination strategy for post-production technologies.

The consortium initiated a partnership with theManufacturing Industries Association of the Philip-pines (MIAP) with the objective to localize produc-tion of needed post-production technologies in thePhilippines. Consortium members will provide theknow-how for technology design and development.MIAP members will produce prototypes for testingand eventually standardize parts for mass produc-tion under a subcontracting scheme. A 3-d mecha-nical dryer design workshop was conducted duringwhich consortium engineers and members of MIAPreviewed suitability of different drying concepts.Four different mechanical drying systems were con-ceptualized, and a multi-agency dryer design groupwas formed. The first dryer design was transferredto MIAP in November 1999. The prototype, a 6-trecirculating batch dryer, will be field-tested earlyin 2000.


Table 6 continued.

Issue Lessons learned

● These differences need to be consid-ered in the design of the project andthe strategy for carrying it out. For ex-ample, working with the private sectortypically introduces a sense of ur-gency, which can be an advantage ordisadvantage.

Change and ● When proposing and carrying outdealing with change, a common byproduct is anfallout upset in the status quo and vested in-

terests.● Expect opposition to the project and

attempt to engage potential critics.Project responses to criticism shouldconsider the underlying motivation forthe criticism. Also consider how to en-courage many sectors or organizationson-board and how to avoid unfoundedor unnecessary criticism, while re-sponding to genuine concerns in de-veloping partnerships.

● Recognize that opposition to changederives from several motives—opposi-tion to change itself, opposition to theobjectives of the project, disagree-ment with the approach applied, differ-ent agendas (e.g., political or indi-vidual attacks), or misunderstandingsof project activities.

● Recognize that because multisectorpartnerships involve organizations withtheir own unique histories, prejudicesmay already exist on the part of somecritics.

Develop project ● Engage all the collaborating organi-goals collect- zations in the development of projectively, explicitly, goals and its guiding principles.and openly ● Project development should be con-

ducted openly with proactive efforts toexplain the project to potential critics.

● Project partners should define projectmilestones and set up a system formonitoring project implementation andperformance.

Rice quality managementR. Bakker, D.B. de Padua, A.R. Elepaño,R.D. Billate, I.R. Barredo, and M.A. Bell

Quality of milled rice in many countries is low dueto inappropriate management techniques in all as-pects of grain handling. Changes in post-productionmanagement practices will occur only if there is suf-ficient economic incentive. In this respect, imple-mentation of proper standards and grades for milled

rice that are based on consumer preferences areneeded.

We made an exploratory assessment of rice qual-ity from selected retail markets in Laguna Provinceand Metro Manila, Philippines. The objectives wereto evaluate the quality of the milled rice with respectto the existing grades and standards, and to makerecommendations based on our quality assessment.Among 55 samples obtained from rice retailers,only 18 had grades indicated on the label or pack-age. Milled rice quality in terms of head rice wascomparatively low based on NFA standards, withthe majority falling in Grades 2 and 3 (Fig. 5). Evi-dence of mislabeling was observed. The persistenceof names of traditional varieties that are no longergrown suggested that consumers associate particu-lar quality characteristics with these varietal names,standards, and grades. Results of our study werepresented at two major national conferences, andrecommendations were communicated to the appro-priate government agencies. The research method-ology we developed will be used in a nationwidefollow-up study in which IRRI and NFA will col-laborate.

Drying is a key operation to maintain rice qual-ity. As part of a study that explores drying charac-teristics of modern rice cultivars, a series of expe-riments determined the effects of drying air tempe-rature on grain quality, including head rice, white-ness, and seed viability. A two-stage drying ap-proach was used to optimize drying time whilemaintaining grain quality. Results indicated that

5. Head rice and retail market price of 55 milled rice samplescollected in Laguna province and Metro Manila, Philippines.IRRI, 1999.

Not gradedGraded

Grade 350-65%

Grade 265-80%

Grade 180-95%

40

35

30

25

20

15

1040 50 60 70 80 90 100

Price (P kg-1)

Premium95-100%

Head rice (%)


higher drying rates can be used without com-promising head rice recovery and whiteness, andresult in reductions of drying time compared withsingle-stage drying (Table 7). However, results alsoshowed that grain subjected to drying air of 60 °Cor higher lose their seed viability. This study pro-vided useful guidelines for the design of mechani-cal dryers for rough rice.

Socioeconomic studies for technologyimpact, gender, and policy analysis

This research generates information to support plan-ning and prioritization of rice research and to im-prove the understanding of the interface betweenthe diffusion of new technology, socioeconomicequity (including the gender dimension), andalleviation of poverty.

Production of improved rice varietiesin South and Southeast AsiaM. Hossain, V. Cabanilla, D. Gollin,31 G.S. Khush,and G. McLaren

The Impact Assessment and Evaluation Group ofthe Consultative Group on International Agricul-tural Research (CGIAR) initiated a study on theeconomic evaluation of germplasm improvementresearch conducted by the CGIAR centers. TheIRRI Social Sciences Division did the study on ricefor South and Southeast Asia.

Table 7. Drying rate, drying time, and head rice as affectedby drying air temperature in thin layer drying of rough rice(PSBRc 54, first stage = 25–18% moisture content, sec-ond stage = 18–14% moisture content). IRRI, 1999.

Drying air Dryingtemperature rate

(°C) (% h–1) Total Headdrying rice

First Second First Second timea (%)stage stage stage stage

40 40 2.5 1.00 91.6a50 40 10.9 2.3 0.52 90.1a60 40 22.4 2.5 0.44 87.6a70 40 34.6 2.1 0.49 88.5a80 40 60.2 2.3 0.35 84.9b50 50 6.79 0.36 79.3c60 50 21.6 5.3 0.24 84.7c70 50 38.4 5.4 0.20 84.2c80 50 62.0 5.8 0.17 83.4c

aRelative to continuous drying at 40 °C.

We surveyed 28 rice breeding stations in Southand Southeast Asia to collect information on

● number of varieties released,● crosses involved in the released varieties,● breeding objectives,● pool of genetic materials used in breeding, and● most popular varieties adopted by farmers in

the area served by the breeding stations.Rice breeders were asked to enumerate the ge-

netic traits they sought from each parent in each ofthe crosses. Pedigree analysis identified geneticmaterials used in the development of multiple-traitvarieties and determined the contribution of IRRIand NARS in the development of varieties widelygrown by farmers.

PRODUCTION OF VARIETIES

Since 1960, the NARS of South and Southeast Asiahave released about 1,100 varieties of rice (Table 8).They have developed about 35 new varieties peryear since the mid-1970s.

Vietnam’s research system has increased its re-leases of new varieties dramatically since the 1980s.Laos released a number of varieties in the 1990s af-ter a long period with few releases. Cambodia’s re-search system also increased the pace of variety re-leases in the 1990s. In all of these countries, the in-creased rate of releases corresponded to recent in-vestments in the human capital for the rice researchsystem, as well as to increased cooperation with theinternational scientific community. IRRI contrib-uted directly to the germplasm improvement re-search in these countries through bilateral countryprograms.

NARS USES OF IRRI MATERIALS

Direct release of IRRI lines or varieties. Of the1,132 released varieties in the data for which ances-try could be traced, 161 (14%) were IRRI lines re-leased directly in other countries. Differences acrosscountries are noted from the data. Vietnam, Cambo-dia, and Laos released many IRRI lines in recentyears. In earlier years, the Philippines was a majoruser of IRRI-developed varieties. By contrast, Thai-land did not release any IRRI-developed varieties.India and Sri Lanka had fewer than 10% of releasesas direct IRRI-developed varieties.


IRRI-developed varieties appear to have reachedtheir highest level in the late 1970s, when more than20% of all releases in South and Southeast Asiawere IRRI-developed lines (Fig. 6). This cor-responds with the period in which the first modernvarieties were developed with resistance to anumber of important diseases and pests.

Across countries, the proportion of IRRI-devel-oped varieties is notably high in Cambodia,Myanmar, the Philippines, and Vietnam, accountingfor about one-fourth to one-third of total releasedvarieties.

Uses of IRRI materials as parents. We estimatethat about 44% of released varieties originated fromone or more parents developed at IRRI. The numberof IRRI-parents releases appears to have reached apeak in the 1976-80 period (Fig. 7), but there is evi-

dence for a later increase in the 1990s period due toIRRI participation in the germplasm improvementresearch in Cambodia, Laos, and Vietnam. Bangla-desh had the highest proportion of releases in thiscategory, with 48% of all locally bred varieties us-ing at least one IRRI parent. By contrast, only 8%of Thai varieties had an IRRI parent.

In a number of major rice-producing countries,the use of IRRI parents has decreased since the earlyyears of the Green Revolution. In India, for exam-ple, 45% of varieties released during 1971-75 pe-riod had at least one IRRI parent (in addition to the10% of releases that were wholly IRRI-developed).By the 1990s, however, only about 20% of Indianreleases had an IRRI parent. This suggests a changein the respective roles of IRRI and the Indian na-tional program.

Table 8. Number of improved rice varieties released, by country and by time period. IRRI, 1999.

Country Varieties (no.) VarietiesRiceland (no. million

Pre-1970 1971-80 1981-90 1991-98 Total (million ha) ha–1)

Bangladesh 11 24 19 19 73 10.2 7.2Cambodia 0 0 6 24 30 1.9 15.8India 35 151 202 66 454 42.5 10.7Indonesia 16 21 24 14 75 11.2 6.7Laos 8 0 0 8 16 0.57 28.1Malaysia 10 14 12 5 40 0.65 61.5Myanmar 5 16 27 5 53 5.6 9.5Pakistan 18 4 4 1 27 2.3 11.8Philippines 9 32 16 37 94 3.5 26.9Sri Lanka 23 10 13 11 57 0.66 86.4Thailand 61 12 15 8 96 9.2 10.4Vietnam 30 9 35 43 117 7.1 16.5 Total 226 292 373 241 1132 95.4 11.9

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00Pre-1970 1971-75 1981-85 1986-90 1991-95 1996-98

Time period

0.05

1976-80

0.420.39

0.32

0.24

0.31

0.39

0.25

0.20

0.15

0.10

0.05

0.00Pre-1970 1971-75 1976-80 1981-85

Time period

0.10

0.18

0.21

0.15

1996-981986-90 1991-95

0.050.04

0.14

6. IRRI crosses released as varieties, as percent of total releases.IRRI, 1999.

7. Releases with IRRI parents, as percent of total releases. IRRI,1999.


IRRI provision of other ancestors. As NARS ca-pacity grew, IRRI increasingly provided them withelite lines for use in breeding. Those were used asparents of released varieties but sometimes they ap-pear as grandparents or more remote ancestors. Thishas begun to create a pool of genetic resources thathave IRRI ancestry but not at the parental level.Excluding IRRI crosses and varieties with IRRI par-ents, this pool accounted for 78 released varieties(7% of the total). The varieties that fall in this cat-egory are of relatively recent origin (Fig. 8).

The overall contribution of IRRI to the improvedgermplasm released by NARS can be seen from

Table 9. The contribution was highest in the Philip-pines, Bangladesh, and Indonesia and lowest inThailand, Cambodia, and Laos, where farmers arestill growing mainly traditional varieties.

Types of IRRI materials in use. Are national pro-grams today using IRRI materials that were alreadyavailable a decade or two ago? To what extent arenewer IRRI materials being used? To answer thosequestions, we identified the date of crossing forevery IRRI material appearing in the genealogy ofa released variety. We then asked how many of thereleased varieties make use of materials crossed atIRRI after 1990, after 1980, etc. The aggregateddata for all 12 countries are summarized in Table10.

IRRI’s first semidwarf varieties (IR5 and IR8)were crossed during 1962-64, although they did notreach a usable stage for breeding or multiplicationuntil 1966. A second generation of IRRI materialswas developed from crosses made in the periodfrom 1965 to 1971. This included the widely usedvarieties IR20, IR22, and IR24, along with lesswidely used IR26, IR28, and IR29. Some of thosevarieties displayed useful insect and disease resist-ance, with several drawing on the hardy Indian va-riety TKM6. In our data set, 137 released varietiescan be traced to the second-generation IRRI materi-als, but have no subsequent IRRI lines in theirgenealogies.

Table 9. Contribution of IRRI to released varieties in 12 countries of South andSoutheast Asia. Numbers are proportion (%) of total releases. IRRI, 1999.

IRRI crosses Varieties with Varieties linkedreleased as Varieties with IRRI material with IRRI

Country varieties an IRRI parent in the previous materialsancestors

Bangladesh 0.12 0.48 0.10 0.70Cambodia 0.27 0.03 0.03 0.33India 0.06 0.31 0.07 0.44Indonesia 0.20 0.36 0.11 0.67Laos 0.00 0.38 0.00 0.38Malaysia 0.13 0.30 0.07 0.50Myanmar 0.30 0.30 0.00 0.64Pakistan 0.26 0.22 0.00 0.48Philippines 0.35 0.32 0.04 0.71Sri Lanka 0.04 0.23 0.26 0.53Thailand 0.00 0.08 0.03 0.11Vietnam 0.32 0.30 0.05 0.67 Total 0.14 0.29 0.07 0.50

0.00

0.01

0.03

0.12

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00Pre-1970 1971-75 1976-80 1981-85

Time period

0.11

1996-981986-90

0.100.10

1991-95

8. Percent of released varieties with IRRI ancestry other thandirect release or immediate parents. IRRI, 1999.


In the succeeding years, disease and insect resist-ance continued as a major goal of IRRI breeding. Amajor innovation was the incorporation of Oryzanivara, conferring resistance to the grassy stunt vi-rus into the IRRI breeding pool. Varieties based onthat germplasm developed from 1972 to 1976 in-cluded IR32, IR38, and IR40. Another set of varie-ties with multiple disease resistance was rep-resented by IR36 and IR42. This third generation ofmaterial provided the foundation for 20% of the va-rieties released in the 1980s and the early 1990s.The following generation of IRRI breeding materialconsisted of crosses made at IRRI from 1977through 1980. Those incorporated the charac-teristics of shorter growth duration and improvedgrain quality. An additional 49 varieties in the dataset include crosses made at IRRI in this period intheir pedigrees. All but three of those were releasedafter 1986, accounting for about 11% of all releasesin the period. The total number of varieties based onthis germplasm is not large, but is significant. Oneof the crosses made resulted in IR64, which is themost widely cultivated rice variety in the world.

Only 17 varieties (2%) include crosses made atIRRI in 1981-98 in their pedigrees. Varieties in thedata set from such relatively recent IRRI crosseswere not effected. It is normal to see time lags of 10years or more between the time a cross is made atIRRI and the time it results in a variety released bya national program.

IRRI as a source of traits. IRRI materials wereinitially attractive to national breeding programs asa source of a single trait—the semidwarfing gene.However, IRRI varieties soon incorporated bundlesof other useful traits and characteristics.

The number of landraces in the genealogy of areleased variety offers a useful measure of breedingintensity or complexity. To assess the IRRI contri-bution to the overall bundling process, we measuredthe number of distinct landraces in the genealogiesof released varieties and the extent to which thatnumber is dependent on IRRI breeding.

The average number of landraces per releasedvariety is just above 6.4 for the whole data set. Froma low of about two landraces released variety–1 inthe pre-1970 period, the average number increasedto more than 11 for 1996-98. This implies a substan-tial increase in the genealogical complexity of suc-ceeding generations of varieties and substantial ge-netic diversity within a single variety. In turn, thisimplies greater bundling of desirable traits. Of the6.4 landraces in the genealogy of an average re-leased variety, IRRI has contributed about 4.6,meaning that national programs are typically com-bining an IRRI variety with a single landrace (Ta-ble 11).

IRRI has put together packages of traits that thenational programs find useful. The IRRI rices areoccasionally useful in their existing form and arereleased directly by NARS. But more often, theIRRI rices lack one or more locally important traits.In those cases, the NARS use IRRI materials asbuilding blocks to get desirable bundles of traits.

Farmer adoption of improved rices. By the early1990s, nearly 75% of the rice area in Asia wasgrowing so-called high-yielding or modern varie-ties. The rate of adoption varied across countries,often depending on the development of irrigationinfrastructure. The adoption of modern varieties inEast Asia, where most of the rice land is irrigated,

Table 10. Distribution of released varieties by the generation of IRRI materials intheir genealogies. IRRI, 1999.

Period of Without IRRI With IRRI material (%) crossed duringrelease material

(%) Pre-1965 1965-71 1972-76 1977 and later

Pre-1970 90.3 8.7 0.0 0.0 0.01971-75 41.0 34.4 12.3 12.3 0.01976-80 32.9 28.2 19.4 19.4 0.01981-85 38.3 25.5 16.5 18.1 1.61986-90 47.0 16.2 9.2 21.6 5.91991-98 52.5 5.8 5.8 20.6 15.3 Total 48.2 18.1 12.1 15.8 5.8


was complete in the 1970s. In Myanmar, Cambodia,and Laos, where rice is grown mostly as rainfedlowland, farmers still grew traditional varieties inthe early 1990s. The Philippine rate is more than90% and Indonesia is about 75%. In Bangladesh,farmers grow more than 700 varieties, with 40 mod-ern varieties accounting for 60% of land use.

IRRI’s contribution to popularly grown varie-ties. National-level data on the actual use of specificvarieties by farmers are typically lacking except for

Indonesia and Bangladesh. We created a list ofpopular varieties grown in several regions from vil-lage studies and sample surveys IRRI conducted incollaboration with NARS. For regions for which theinformation was not available, we requested breed-ers to report the five most widely grown varieties inthe area served by their station. The popularlygrown varieties are listed in Table 12. We did apedigree analysis of those varieties to assess therelative contribution of IRRI vis-à-vis the NARS.

IR64 is the most popular variety in the regionand is grown in extensive areas in Indonesia, Philip-pines, and Vietnam and in the Indian states ofAndhra Pradesh and Orissa. We estimate that IR64is grown to nearly 13 million ha of rice land in Asia.IR8 and Jaya, which were released in 1960s, stillremain popular among farmers in several Indianstates and in Bangladesh. Other IRRI varietiesamong the top five popular varieties are IR36, IR42,and IR66. Mashuri, a variety introduced in the early1960s, and Swarna, a selection from Mashuri in theearly 1980s, are the most popular varieties grown inseveral Indian states and in Nepal.

An earlier IRRI study similar to ours found thatin 1975, Jaya (a semidwarf short-duration varietydeveloped in India) was the most popular variety inAsia, followed by IR8. By 1982, IR8 was replacedby IR36 and was estimated grown on about 11 mil-

Table 12. Top five most popular rice varieties grown by farmers in 12 countries ofSouth and Southeast Asia. IRRI, 1999.

Country Popular varieties

Bangladesh BR11, BR14, BR3, IR8, BR10Cambodia IR66, Kesar, Neang Minh, Phka KhneyIndia

Andhra Pradesh BPT5204,IR64, MTU5182, Swarna, BPT3291, Tella HamsaBihar Sita, Rajashree, IR36, Mashuri, KaniharMadhya Pradesh Safri, IR36, Swarna, Mahamaya, KrantiPunjab PR111, Pusa44, PR106, PR113, IR8Orissa Swarna, CR1030, Mashuri, Sabiti, IR64Karnataka MTU1001, Jaya, IR64, IR20, IR8Tamil Nadu Ponni (Mashuri), ADT36, ADT39, IR50, CO 43Uttar Pradesh Sarjoo 52, Pant Dhan 4, Mashuri, NDR118, NDR97

West Bengal Swarna, IET5656, IET4786, IR36, JoyaIndonesia IR64, Cisadane, Membermo, IR42, IR36Laos TDK1, RD6, KDML 105, Dokmay, Mueng NgaMalaysia MR84, MR167, MR77, IR42, SemerakMyanmar IR13240, IR92224, Mashuri, IR5, InmayebawPhilippines IR64, PSBRc 14, PSBRc 28, PSBRc 18, PSBRc 34Pakistan Super Basmati, Basmati 1385, KS 282, IR6, Basmati 198Thailand RD6, KDML 105, SPR60, RD23, RD10Sri Lanka BG300, BG352, BG94, BG350, BG450Vietnam IR64, OM997, IR50404, IR56279, DT10

Table 11. Average number of landraces in released varie-ties. IRRI, 1999.

Landraces Landraces Landracesper variety introduced introduced

Country (no.) through IRRI independentmaterial (no.) of IRRI (no.)

Bangladesh 6.6 4.9 1.7Cambodia 6.9 5.8 1.1India 5.1 3.1 2.0Indonesia 9.4 6.9 2.5Laos 6.2 5.3 0.9Malaysia 7.2 4.6 2.6Myanmar 7.4 6.1 1.3Pakistan 3.9 2.6 1.3Philippines 12.0 10.8 1.2Sri Lanka 6.6 2.8 3.8Thailand 2.1 0.8 1.3Vietnam 8.4 7.3 1.1 Total 6.4 4.6 1.8


lion ha. By the early 1990s, the most popular posi-tion was taken over by IR64.

In 1975, about 60% of the widely grown varie-ties were locally developed, 30% were introducedfrom IRRI, and 10% from another country. Thesituation has changed little since then. Our datashow that 67% of the popular varieties were devel-oped in the country, 29% came from IRRI, and only4% originated from another country.

We analyzed the distribution of the origin of alldistinct ancestors that appeared in the genealogy ofthe widely grown varieties. Of the total ancestors,45% originated from IRRI materials, 23% from In-dia, 7% from Sri Lanka, and 4% each from Indone-sia and Thailand. IR8 was the most frequently usedIRRI material occurring in the ancestry of thesepopular varieties, followed by IR8608 (51%). Ofthe 24 IRRI materials that were found in the ances-try of 15% or more of these popular varieties, 11were developed in 1960s and 13 in 1970s. Materi-als developed since then have had insignificant con-tribution to the development of the popularly grownvarieties.

Demand for specialty rices: implicationsfor technology developmentM.A. Sombilla and M. Hossain

Rice regarded as a top-quality variety in one coun-try may be considered low-quality rice in anothercountry. Quality is primarily classified based ongrain length, head rice content, and method of mill-ing. A secondary classification is based on amylosecontent, which accounts for degree of stickiness andaroma. Of the different types of rice, long- and me-dium-grain rice with intermediate amylose content(nonglutinous) dominates production, consumption,and trade.

CHANGING STRUCTURE IN FOOD DEMAND

A notable pattern in rice consumption is that withgrowing income, people express preferences forhigher quality rice once caloric needs have beenmet.

With respect to incomes and prices, demand forbetter quality rice is more elastic than demand forquantity. This means that as income grows, demand

for rice grows less than proportionately and suchdemand shifts to better quality rice. Similarly, asrice prices decline, consumers do not propor-tionately increase quantity consumed but shift topurchasing more expensive, better quality rice.

POLICY IMPLICATIONS

The evidence suggests that grain quality will be-come increasingly important in demand for rice.This has strong implications on future developmentof production and marketing technologies. Rice sci-entists need to continue focusing on the develop-ment of varieties that are able to yield high and atthe same time have the potential to capture the pricemargin currently existing between the higher priced(high-quality) traditional varieties and the lowerpriced (low-quality) modern varieties. Iron- and Zn-enriched traditional varieties as well as those withhigh vitamin A content are being crossed with mod-ern rice varieties to increase yields and improve re-sistance to insects and diseases. The availability ofthose varieties will prove valuable to millions ofpoor people in Asia and Africa.

The absence of formal grades and standards ofrice in the international markets adds to market in-efficiency in the commodity. The proxy measure-ments used, based on physical quality (head rice re-covery, length, and cleanliness), do not tell the en-tire story of quality preferences. A reliable methodfor variety classification that takes into considera-tion all characteristics, including cooking quality, isneeded for rice trading to gain more credence.

Implementing ecoregional approachesto improve natural resource managementin Asia

The focus of the ecoregional approach is conserva-tion and management of natural resources to devel-op sustainable food production systems, taking intoaccount socioeconomic factors in biophysically de-fined ecoregions. One focus of the ecoregional ap-proach in natural resource management is to iden-tify agricultural production systems that are sustain-able and have least impact on the state of the natu-ral resource base.


Market integration, agriculturaldiversification, and erosion risk in northernThailandG. Trebuil, S.P. Kam, T. Boch, Charal Thong-Ngam, F. Turkelboom, and A. Begue

In the fragile agroecosystems of mountainous areasin Southeast Asia, accelerated erosion by concentra-ted runoff is a major problem that limits theproductivity and sustainability of cropping systems.Cropping systems are rapidly diversifying in manyof the upland areas, often with less emphasis on up-land rice and more on cash crops. The effect ofchanges in cropping systems on erosion risk ispoorly documented.

A study in the uplands of northern Thailanddocumented land use changes between 1990 and1994 and assessed the impact of the changes on ero-sion risk at the field- and small-watershed level. Thestudy site is the Mae Salaep watershed in the ex-treme northern region of Thailand. This watershed,which is farmed by Akhas highlanders, is at an ad-vanced stage of diversification of agricultural pro-duction systems. Most of the cultivated fields are onslopes of 10–40%, and sometimes as steep as 60%.Expansion of farmland into surrounding forest areasis limited due to a national forest protection law. Asa result, the land is subjected to more intensive cul-tivation.

A multiscale approach was adopted. We linkedresults of a 2-year field-level agronomic survey(1998 Program Report) with a geographic informa-tion system (GIS) analysis of the spatial distributionof land use changes in the study sites. From the de-tailed, field-level agronomic survey, we identifiedkey indicators and critical thresholds of soil erosion.

CHANGES IN CROPPING SYSTEMS

TO REDUCE EROSION RISK

Figure 9 shows the spatial distribution of farm lotsand crops in the Mae Salaep watershed in the 1990and 1994 WS. A number of features of the changesin the cropping systems during this 4-year periodhad the effect of reducing erosion risk:

● A decrease in the size of fields, hence reducingtheir slope lengths (Fig. 10).

● An increase in the share of fallow land,especially on steep slopes (Fig. 11).

● A decrease in the production of upland rice,which is a subsistence and high erosion-riskcrop.

● Limited expansion of irrigated rice on benchterraces (Fig. 9).

● Recent appearance of a diversity of horti-cultural and perennial cash crops as indicatedby map legends in Figure 9.

EROSION RISK DECREASE

Table 13 summarizes the categories of erosion risk,based on critical thresholds of slope length andslope steepness, for the main cropping systems inthe Mae Salaep watershed. Figure 12 shows the spa-tial pattern of erosion risk in the Mae Salaep water-shed for the 1990 WS. Figure 13 shows the changesin erosion risk between 1990 and 1994, displayed inthree-dimensional perspective in relation with thetopography of the Mae Salaep watershed.

The agricultural diversification process for theMae Salaep watershed observed during the early1990s tends to decrease the risk of land degradationcaused by accelerated erosion. The cropping situa-tions that are of high erosion risk in the watershedcan be identified spatially for on-farm soil and wa-ter conservation interventions to decrease erosionrisk in Mae Salaep fields.

Program outlook

A new functional genomics project will be in fulloperation in 2000. It provides the backbone for genediscovery that will drive germplasm improvement.Through the use of genomewide approaches, weaim at understanding complex biological pathwayscontrolling desirable agronomic traits. We havebuilt considerable genetic resources essential forassigning biological functions to DNA sequencesproduced by genome sequencing projects of riceand allied species. The utility of these genetic mate-rials will be amplified with the application of genearray analysis.

We will continue to build infrastructure and fa-cilities to apply high-throughput, genomewideanalysis of genetic stocks. We will strengthen thebioinformatics component with recruitment of newstaff members. Emphasis will be on building pheno-type databases that would link with internationalgenome databases.


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10. Distribution of field size in the Mae Salaep, Thailandwatershed in the 1990 and 1994 wet seasons. IRRI, 1999.

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10%

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11.Land use dynamics in the Mae Salaep, Thailand watershed between 1990 and 1994. IRRI, 1999.

Table 13. Matrix of erosion risk for main cropping systems in the Mae Salaep, Thailand water-shed, 1990 WS. IRRI, 1999.

Slope Land use classescharacteristics

Fallow perennial Cash crop Cash cropAngle (5) Length (m) paddy with low value with high value Upland rice

paddy/soy added added

<47 <25 Low Low Low Low>25 Low Medium Medium Medium

<47 <25 Low Medium High High>25 Low Medium High High


13. Changes in erosion risk in the Mae Salaep, Thailand watershed between 1990 and 1994, IRRI, 1999.

12. Spatial distribution of erosion risk in the Mae Salaep, Thailandwatershed in 1990. IRRI, 1999.

Ban Mae

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Our biotechnology project will be strengthenedby investment in functional genomics research. Theproject will emphasize development of tools andproducts for immediate applications. Priority willbe given to delivery of products that help removekey constraints in different rice ecosystems. We willalso emphasize the development of productive va-rieties in heterogeneous and marginal lands whererice is often the only source of nutrients in people’sdiet. The ARBN will continue to be our pipeline todeliver these products to NARS.

Because of the inherent variability of pest-in-duced problems, there is a continual need to developmanagement tactics using sound ecological princi-ples. We will foster strong disciplinary research inpest science to address issues central to sustainablepest management. In particular, we will continueefforts to understand the role of biodiversity in theprevention of pest outbreak in environments withdifferent levels of production intensity. We will ap-ply ecological principles to develop practices infarmers’ fields where sustainable pest managementand economic impact can be achieved.

Knowledge-intensive technologies will be in-creasingly important in rice farming. However,without effective means to transfer knowledge andtechnologies, there will be a delay in bringing im-proved technology to benefit farmers. We will fo-

cus on identifying and evaluating technology andknowledge delivery systems. We will continue touse case studies to determine the social, economic,and technical factors that determine successfultransfer of technology and knowledge acquisition.

Our project on socioeconomic studies will beclosely linked to work on transfer of technology andknowledge acquisitions in that we are interested inunderstanding technology diffusion and impact.The primary goal is to generate information to pro-vide the rationale for effective planning andprioritization of rice research in the near and longterm. The unique feature of this project is to under-stand socioeconomic dimensions of technologicalimpact on poverty alleviation. The use of improvedgermplasm will continue to be central to improvingproductivity and food security in marginal lands.We will analyze the implications of quality prefer-ence of rice and marketing on research priority andincome generation for farmers.

In research initiated as a systemwide initiative toaddress issues on natural resource management at aregional scale, focus will be on integrating method-ologies and available data to develop practical rec-ommendations on resource management policiesrelevant to rice production. We will concentrate onpilot areas to generate data for natural resourcemanagement in larger regions.

Research programsRice genetic resources: conservation, safe delivery, and use

CONSERVATION OF RICE AND BIOFERTILIZER GENETIC RESOURCES 106Germplasm and information exchange 106

Indonesia 106Lao PDR 106Madagascar 106Malaysia 107Myanmar 107Nepal 107Philippines 107Swaziland 107Vietnam 107

Genebank management 107Germplasm characterization 108Data management 108Training 108Conservation of biofertilizer germplasm 108Biosystematic studies of wild rices 108Dynamic systems of genetic conservation 108

DELIVERY OF GENETIC RESOURCES: THE INTERNATIONAL NETWORKFOR GENETIC EVALUATION OF RICE (INGER) 1121999 INGER nurseries 112

Distribution of nurseries 112Preparation of the 2000 INGER nurseries 112Utilization of 1998 INGER entries 112Data management 113

Processing and distribution of test materials for the Upland Rice Research Consortium and Breeding Network 113Maintaining genetic diversity of blast inoculum in the International Rice Blast Nursery (IRBN) 113

THE INTERNATIONAL RICE INFORMATION SYSTEM 113ICIS development 114IRIS development 114

SEED HEALTH TESTING SERVICES 115

PROGRAM OUTLOOK 116


Rice genetic resources: conservation,safe delivery, and use

Conservation of rice and biofertilizergenetic resources

Germplasm and information exchangeM.T. Jackson, B.R. Lu, G.C. Loresto,and S. Appa Rao

IRRI received more than 3,300 samples of Oryzasativa and 41 samples of wild species for long-termconservation.

INDONESIA

A collecting trip to Irian Jaya resulted in 29 samplesof wild species from Merauke—O. officinalis (9),O. longiglumis (7), O. rufipogon (6), and O.meridionalis (7). Eight traditional rice varietieswere also collected. The collection of O.meridionalis, an annual diploid species consideredendemic to Australia, was its first documentation inIrian Jaya. Seventeen wild rice samples and eightcultivated rice were brought to IRRI for long-termconservation.

LAO PDR

IRRI and Lao PDR collectors brought 2,402 sam-ples of cultivated rice and 16 samples of wild riceto IRRI for long-term preservation.

MADAGASCAR

National personnel explored the provinces of thenortheast coastal area (Toamasina, Vavatenina,Fenoarivo-Est, and Soanierana-Ivongo) in mid-January. The varieties Marotia and Botojingo werecollected.

Applications of information technology for datamanagement were important program activities in1999. Improvements were made to the genebankdata management system, the recently developedintegrated data management system for the Inter-national Network for Genetic Evaluation of Rice(INGER) was installed on the Institute’s intranet, anda database for the Seed Health Unit was implemen-ted. Additional modules were developed for Interna-tional Rice Information System (IRIS), and morepedigree data were added. A genetic resources homepage was opened on the IRRI web site.

This was the last year of the rice biodiversityproject funded by the Swiss Agency for Developmentand Cooperation (SDC). Partners in national agri-cultural research systems (NARS) completed most ofthe germplasm collecting planned at the initiation ofthe project in 1995.

Rice genetic resources: conservation, safe delivery, and use 107

Three upland varieties were collected in thefield. Nine photoperiod-sensitive varieties were col-lected from on-farm storage. Populations of O.longistaminata were found along a river near thevillage of Anisobe, 20 km from Toamasina. Theirpanicles were sterile and only vegetative sampleswere taken.

IRRI received 253 samples of cultivated rice col-lected during 1997-99. Seed samples collected in1997 were multiplied in Madagascar.

MALAYSIA

Researchers and extension workers from the Malay-sian Agriculture and Research Development Insti-tute, the Agricultural Research Center of Sarawak,and extension workers from Sabah collected 435samples of cultivated rice from Sarawak, Sabah,and Peninsular Malaysia. Nineteen samples of wildspecies and six samples of weedy rice were col-lected from Terengganu and Kelantan areas of Pe-ninsular Malaysia.

MYANMAR

Extension workers from Kachin, Kayah, Kayin,Rakhine, and Shan states and from Magwe,Sagaing, and Tanintharyi divisions collected 647samples of cultivated rice during 1998-99. Morethan 45 wild rice samples were collected fromYangon and Bago divisions. IRRI received 649samples of cultivated rice and eight samples of wildrice for long-term conservation.

NEPAL

Scientists from the Agricultural Botany Division,Nepal Agricultural Research Council, and an IRRIcollector, collected wild rice species in central andeastern Nepal. Fifty samples of O. rufipogon, O.nivara, and some weedy types were collected.Three rare local rice varieties were also collected.

Oryza rufipogon is less common in the centraland eastern Nepal than in mid-western and westernNepal. It is found as large populations in swampsand fishponds with adequate water supply. Allpopulations of O. rufipogon encountered appearedto be photoperiod-sensitive.

Duplicates of the 53 samples collected werebrought to IRRI for long-term conservation.

PHILIPPINES

The Philippine Rice Research Institute sent 51 sam-ples of O. sativa to IRRI for long-term conservation.They were collected from Surigao del Sur,Catanduanes, Quirino, and Palawan provinces.

SWAZILAND

IRRI received 17 samples of wild species and onecultivated rice from Swaziland.

VIETNAM

Work in three Vietnam provinces in the north, onein the central plateau, and three in the south resultedin 157 varieties collected. Seeds collected in 1997were regenerated in 1998 and processed for duplica-tion at IRRI. Germplasm collected in 1998 was re-generated during 1999.

Genebank managementM.T. Jackson, F. de Guzman, R. Reaño, andS. Almazan

Germplasm multiplication activities during the1999 dry season (DS) included 4,600 newly ac-quired samples of O. sativa and 508 samples of wildspecies. An additional 3,100 O. sativa accessionswere rejuvenated with 71 entries transferred to thenursery screenhouse because they were either pho-toperiod-sensitive or had poor germination. High-quality seeds were harvested from all but four ofthose accessions. About 250 O. glaberrima acces-sions were also successfully rejuvenated. About 300wild species accessions were rejuvenated in thenursery screenhouse.

We added 5,278 accessions from the 1998 wetseason (WS), 1998 DS, and 1999 DS harvests forlong-term conservation in the International RiceGenebank Collection. The viability of about 10,000seed samples from the Active Collection was moni-tored. The viability of more than 5,200 samples wasdetermined before assigning new accession num-bers and placing them in long-term conservation. Amarked decline in viability was observed for theglutinous varieties, and some wild species acces-sions that had been stored for more than 6 years. Aspecial study of glutinous varieties will be initiatedto understand their poor storage potential.


We distributed more than 6,000 seed samples inresponse to 169 from 26 countries. Furthermore werestored 1,189 samples to Bangladesh (700), India(487), and Surinam (2). As part of the existingagreement for security backup storage, 9,321 acces-sions were sent to the USDA’s National Seed Stor-age Laboratory (NSSL) at Fort Collins, Colorado.More than 95% of IRRI-registered accessions arenow safely duplicated at the NSSL.

Germplasm characterizationM.T. Jackson, R. Reaño, and S. Almazan

We completely characterized 2,600 accessions forvegetative and reproductive traits during 1999 WS.Panicles were taken for postharvest characteri-zation. Almost 200 O. glaberrima and about 90% ofthe more than 2,000 O. sativa accessions from the1998 WS planting were completely described forpostharvest traits. Newly acquired wild speciessamples (370) were characterized for both vegeta-tive and reproductive traits during their initial mul-tiplication in the nursery screenhouse.

Data managementM.T. Jackson. A.P. Alcantara, and E.B. Guevarra

We made several modifications to the InternationalRice Genebank Collection Information System(IRGCIS) to improve its operation, to generate re-ports on the status of the newly acquired samples,and to facilitate selection of samples for initial seedincrease and seed management. Because theIRGCIS database was developed in Oracle v.7.2and its application was in Developer 2000 v.1.2, wereviewed the system for Y2K compliance and madenecessary modifications to upgrade the system toOracle v.8 and Developer 2000 v.1.5.

During 1999, we updated IRGCIS with informa-tion on newly received samples (22 batches with atotal of 8,497 samples). Master files were upgradedwith morphoagronomic characterization data fromthe 1995 WS (2,297 O. sativa accessions), and the1996 WS (1,707 O. sativa and 197 O. glaberrimaaccessions). We responded to 36 requests fromIRRI staff members and 29 requests from outsideIRRI for information on conserved germplasm. Thestatus of germplasm designated to the Food andAgriculture Organization (FAO) was reviewed anda revised list submitted to FAO.

Our data management staff improved severalfeatures of the Lao genebank data management sys-tem (LaoRIS). That work included automatic gen-eration of different reports on germplasm conservedsuch as the lists of unique variety names and theirmeaning, and conserved germplasm by provinceand district. LaoRIS was updated with more than2,400 newly collected accessions.

TrainingG.C. Loresto, S. Appa Rao, B.R. Lu, and M.T.Jackson

A 2-d workshop in Irian Jaya covered identification,field collection, and conservation of wild rice spe-cies. Fifteen workers from the agricultural exten-sion offices of Wamena, Monokwari, and Merauke,the agricultural research station of Merauke, andfrom different government units of Jayapura partici-pated.

A Lao PDR scientist worked with Laogermplasm in long-term conservation at IRRI dur-ing a 3-wk on-the-job training in genebank and datamanagement.

Conservation of biofertilizer germplasmJ.K. Ladha and T.S. Ventura

During 1999, we supplied 10 Azolla, 45 N2-fixingbacteria, 28 Rhizobium, 11 blue-green algae, and 30aquatic legume samples in response to 25 requestsfrom 10 countries. We sent duplicate samples of thebacteria and Rhizobium collections at IRRI to thePhilippine Network of Microbial Culture Collec-tions.

Biosystematic studies of wild ricesB.R. Lu, M.T. Jackson, A. Juliano, and M.E. Naredo

Intraspecific crosses of African O. longistaminataand interspecific hybridization between O.longistaminata and AA genome species from Asia,South America, and Australia resulted in more than300 hybrids from more than 1,000 crosses and30,000 pollinated spikelets. The crossability of O.longistaminata with other AA species was rela-tively high. However, germination of the hybridseeds was low compared with those fromintraspecific crosses of O. longistaminata and frominterspecific combinations between other AA ge-


nome rice species. A post-fertilization barrier be-tween O. longistaminata and other rice species isevident. The reproductive isolation mechanism ofO. longistaminata is therefore different from otherAA genome rice species studied.

The biosystematic relationships of the O. ridleyicomplex were studied through morphologicalanalysis, inter- and intraspecific hybridization, mei-otic analysis, and fertility determinations of the pa-

rental accessions and inter- and intraspecific hy-brids. Seed set of the crosses was largely variableamong the combinations. Meiosis was normal inintraspecific hybrids of O. ridleyi and O.longiglumis, as well as in hybrids between O. ridleyiand O. longiglumis (Fig. 1), indicating a close ge-nomic relationship between the two species. Thefertility data showed a more complicated pattern(Tables 1 and 2), suggesting a geographic differen-tiation pattern of the populations of the two species.The taxonomy of the O. ridleyi complex must berevised to take into account the geographical distri-bution and associated variation patterns of popula-tions within the complex. Morphological and ran-domly amplified polymorphic DNA (RAPD) data(Fig. 2) strongly support the geographic differentia-tion pattern of the O. ridleyi complex.

The genetic diversity of O. meridionalis (35 ac-cessions) was studied using RAPD and isozymemarkers. O. meridionalis samples from Queenslandhave RAPD variation patterns distinct from those insamples from the Northern Territory and WesternAustralia, demonstrating the genetic diversity of thespecies across its geographic distribution in north-ern Australia.

The herbarium of wild species was upgraded, theidentity of the samples was confirmed, and a data-base in Microsoft Access 7 was developed to sup-

1. Meiosis of the interspecific hybrid between Oryza longiglumis(IRGC 106525) and O. ridleyi (IRGC 100821), showing fullchromosome pairing (24 ring bivalents). IRRI, 1999.

Table 1. Origin and pollen and panicle fertilities of O. ridleyi and O. longiglumisaccessions. IRRI, 1999.

Species and Pollen stainability PanicleIRGC accession Origin (%)a fertility (%)a

number

O. ridleyi100820 Thailand 63.0 (56.1–69.9) 40.2 (29.3–47.0)100821 Thailand 81.2 (60.5–97.2) 46.8 (30.9–61.5)100877 Thailand 63.0 (10.8–91.6) 43.9 ( 5.1–66.6)101453 Malaysia 84.1 (83.6–97.0) 34.0 (16.7–58.5)105366 Thailand 85.3 (78.6–91.1) 36.3 (19.2–57.4)105973 Indonesia 71.7 9.6106028 Thailand 96.6 61.6 (46.7–79.9)106259 Papua New Guinea 63.0 53.5106471 Malaysia 57.4 0.9

O. longiglumis100974 Indonesia 69.8 (23.4–87.2) 39.5 ( 1.2–60.8)105147 Indonesia 46.1 ( 3.2–93.4) 21.4 ( 1.4–51.4)105148 Indonesia 84.0 (79.0–89.7) 59.8 (55.2–64.4)105562 Indonesia 61.2 (50.9–66.7) 67.9 (52.9–63.8)106525 Papua New Guinea 76.3 (63.9–93.3) 70.4 (52.1–79.2)

aRange (%) in parentheses.


Table 2. Pollen and panicle fertilities of intra- and interspecific hybrids of O. ridleyiand O. longiglumis. IRRI, 1999.

Combination Pollen stainabilitya (%) Panicle fertilitya (%)

O. ridleyi × O. ridleyi101453 × 105366 88.1 (72.5–97.4) 50.9 (40.5–63.8)105366 × 106259 1.0 ( 0 – 2.0) 1.6 (0.67– 2.5)106259 × 105366 2.7 0.2

O. longiglumis × O. longiglumis105147 × 106525 81.4 (67.6–92.8) 59.0 (51.0–70.6)106525 × 105147 80.6 66.4106525 × 105148 71.1 (40.2–90.3) 51.4 (40.9–64.2)

O. ridleyi × O. longiglumis105366 × 105147 10.1 (1.0–21.0) 3.9 (1.0–9.0)105366 × 106525 4.8 0.6106259 × 106525 1.4 (0–2.8) 0

O. longiglumis × O. ridleyi105147 × 106028 11.9 (0.1–18.9) 4.6 ( 0.8– 8.8)106525 × 100821 13.9 (3.4–27.5) 20.4 (17.7–22.2)106525 × 100877 7.0 (2.4–10.5) 26.3 (16.2–31.3)106525 × 101453 5.6 (0 –13.0) 15.0 ( 9.5–18.4)106525 × 105366 9.5 (3.1–20.2) 4.4 ( 0.2–19.2)106525 × 106259 10.7

aRange (%) in parentheses.

port the biosystematic studies and conservation ofthe wild rice collection.

Dynamic systems of genetic conservationJ.L. Pham, S.R. Morin, M. Calibo, M. Belen, andS. Quilloy

The continuation of genetic and socioeconomicstudies in India, Vietnam, and the Philippines led toa more detailed description and analysis of the ricediversity on-farm and its management by farmers.

We analyzed the genetic diversity of 179 acces-sions (78 variety names) from 16 central Vietnamvillages. Surveys had shown the sets of varietiesgrown by farmers for DS and WS are different. InDS, traditional and modern varieties respectivelycontribute three and nine specific alleles (i.e., allelesnot found in the other category), but in WS, the re-verse is true with traditional and modern varietiesrespectively contributing nine and three specificalleles. However, when only the five most fre-quently grown traditional or modern varieties areconsidered, we observed that WS varieties had onlythree specific alleles contributed by modern varie-ties vs 11 by the traditional ones. The contributions

of traditional and modern DS varieties were identi-cal (five specific alleles).

These results demonstrate that traditional andmodern varieties contribute specifically to the over-all genetic diversity. This is particularly true for thevarieties grown during WS, the main rice-croppingseason. It also shows that the diversity contributedby the modern varieties in DS is threatened becauseit is essentially contributed by rare varieties. On-farm conservation strategies should take into ac-count both traditional and modern varieties.

In India, the analysis of the distribution of varie-ties across eight villages on the Bastar Plateaushowed that most modern varieties were locally dis-tributed. They were present in a small number ofvillages. Moreover, they were grown by a smallnumber of farmers per village (less than three out ofthe 14 farmers per village surveyed).

On the other hand, traditional varieties may bewidespread or only locally distributed. When lo-cally distributed, they may be grown by few or bymany farmers. This reflects the fact that specificvarieties are limited in their distribution becausethey fulfill critical functions within given situations.Others have a more general distribution because


2. A UPGMA dendrogram generated from cluster analysis of 15 accessions of Oryza ridleyi (R) and O.longiglumis (L), from Indonesia (I), Malaysia (M), Papua New Guinea (P), and Thailand (T), based on135 RAPD markers (including the monomorphic and polymorphic bands). IRRI, 1999.

100820_R/T100820_R/T100820_R/T100820_R/T100821_R/T100821_R/T100821_R/T100821_R/T101453_R/M101453_R/M101453_R/M101453_R/M106028_R/T106028_R/T106028_R/T106028_R/T100877_R/T105366_R/T105366_R/T105366_R/T105366_R/T100877_R/T100877_R/T100877_R/T100974_L/I105146_L/I105146_L/I105146_L/I105562_L/I105562_L/I100974_L/I100974_L/I100974_L/I105148_L/I105148_L/I105148_L/I105148_L/I105146_L/I105562–L/I105147_L/I105147_L/I105147_L/I105147_L/I106525_L/P106525_L/P106525_L/P106525_L/P106259_R/P106259_R/P106259_R/P106259_R/P105973_R/I105973_R/I106471_R/M106471_R/M106471_R/M106471_R/M

0.40 0.50 0.60 0.70 0.80 0.90 1.00

Similarity coefficient


they perform better across environments. Farmerschoose specific or general varieties based on severalcriteria, such as soils, hydrology, and slope.

Most farmers grow between two and five varie-ties. We observed no significant farm-level correla-tion between landholding size and number of varie-ties grown. The number of varieties grown is alsohighly variable within a class of landholding. How-ever, landholding is a limiting factor to the numberof varieties grown by a farmer. We also observedthat large landholders tend to grow fewer varieties.

Preliminary results from the microsatellite analy-sis of 26 varieties using 15 primers showed theirhigh diversity, and 49 alleles were detected. Thisconfirms the analysis of agromorphological traits ofmore than 300 samples that revealed an impressivecontinuum of diversity for vegetative and reproduc-tive traits.

Overall, these results demonstrate the need todefine on-farm conservation strategies based on athorough assessment of the agronomic, genetic, andsocioeconomic criteria.

We conceptualize two different approaches toon-farm conservation: 1) make diversity a viableoption for farmers and 2) strengthen farmers’ accessto diversity. Research examined the two ap-proaches.

In the Philippines, we designed a new croppingpattern for the traditional Wagwag varieties in or-der to shorten their duration. We implemented tri-als in the Cagayan Valley to check whether a de-layed planting date would permit rainfed-lowlandfarmers to grow Wagwag varieties without losingthe opportunity to grow modern varieties during thefollowing cropping season.

We initiated an experiment in Huê, central Viet-nam, to test a new strategy for on-farm conser-vation. The first generation of three compositepopulations was multiplied, with two objectives:1) build genetic pools to represent and help preservethe overall genetic diversity grown in this region,and 2) involve farmers in the conservation of ge-netic resources. The three populations will be splitinto subpopulations to be grown by farmers. Thisapproach to on-farm conservation is expected to bedynamic in terms of evolution, and additionally in-crease farmers’ exposure and access to diversity.

Delivery of genetic resources: TheInternational Network for GeneticEvaluation of Rice (INGER)

1999 INGER nurseriesE.L. Javier, S.W. Ahn, C. Toledo, V. Lopez, andR. Reaño

Four hundred and thirty-one breeding lines from 41NARS and 189 lines from IRRI, the InternationalInstitute of Tropical Agriculture (IITA), the Inter-national Center for Tropical Agriculture (CIAT),and the West Africa Rice Development Association(WARDA) were organized into five ecosystem-ori-ented and four stress-oriented nurseries. The stress-oriented nurseries were composed to screen for coldtolerance and resistance to bacterial blight, brownand whitebacked planthopper, and gall midge.

DISTRIBUTION OF NURSERIES

Two hundred and thirty-nine nursery sets were dis-tributed to 30 countries and evaluated at 129 testsites. Seventy-six percent of INGER trials wereconducted by 22 NARS in Asia. Cooperators in Af-rica (Nigeria, Senegal, and WARDA), LatinAmerica (Bolivia, Brazil, Surinam, and CIAT), andEurope (Italy) tested the remaining nursery sets.

Rice scientists from 32 countries requested 358breeding lines and varieties.

NARS and international agricultural researchcenters nominated 786 breeding lines for evaluationin 15 nurseries. They were multiplied during the1998-99 DS to be included as test materials in 2001INGER nurseries.

PREPARATION OF THE 2000 INGER NURSERIES

Observational nurseries for four ecosystems (irri-gated, rainfed lowland, upland, deepwater) andscreening sets for tungro, blast, and problem soilswere processed for evaluation in 2000.

UTILIZATION OF 1998 INGER ENTRIES

Numbers of INGER entries used by participatingNARS for yield testing and hybridization in 1998are in Table 3. Three hundred and ninety-two en-tries from the ecosystem-based nurseries and 283from the stress-oriented nurseries were used as par-


ents in the varietal improvement programs of 13countries. Sixteen NARS evaluated 491 nursery en-tries in advanced yield trials.

DATA MANAGEMENT

INGER data were managed in several databasesbefore 1999. During 1999, we developed theINGER Information System (INGERIS), with ap-plications running in Oracle Version 8, on a dedi-cated server. Three modules that manage data onprocessing incoming seeds, the seed inventory, andnursery data processing were completed and areused routinely by staff members. Modules for seedmultiplication, nursery composition, and makingqueries were also completed. Pedigree and trial dataare managed within the Data and Genealogy Man-agement Systems of the IRIS.

Processing and distribution of test materialsfor the Upland Rice Research Consortiumand Breeding NetworkB. Courtois, S.W. Ahn, and M. Laza

We processed 124 upland rice breeding lines fromBrazil, Colombia, France, India, Côte d’Ivoire,Thailand, and IRRI for evaluation at key test sitesin China, India, Indonesia, and Vietnam.

Maintaining genetic diversity of blastinoculum in the International Rice BlastNursery (IRBN)S.W. Ahn

Effective evaluation of blast resistance requiresmaintenance of a diverse blast race with differentgenetic backgrounds at a test site. The use of a mix-ture of broadly susceptible rice cultivars is recom-mended for spreader rows on which the blast patho-gen can multiply and spread as the inoculum source.

We monitored the population dynamics of theblast pathogen over 11 cycles of sequentialplantings of spreader rows of different compositions(Table 4). The sequential planting technique per-mits monitoring of the long-term interaction of ricecultivar and blast population. We found that a mix-ture of several broadly susceptible cultivars couldsustain a high diversity of blast pathotypes. A mix-ture of several host cultivars for a distinct blast lin-eage also maintained a high diversity of lineage-pathotype combinations. However, use of only onesusceptible cultivar as the spreader row did not sup-port a wide range of pathogenic diversity. There-fore, we recommend use of a mixture of susceptiblecultivars at sites where there is no genetic informa-tion on blast population structure.

The International Rice Information SystemC.G. McLaren

We continued to refine the dynamic link library(DLL) for the Genealogy Management System(GMS) to ensure compatibility with Microsoft Ac-cess and Oracle database systems, and have alsodeveloped a functional DLL for the Data Manage-ment System (DMS). DLLs contain the programsthat allow access to the International Crop Informa-tion System (ICIS) data in any database system. TheICIS installation program was improved and modi-

Table 3. Utilization of 1998 INGER nursery entries by par-ticipating NARS.

Entries utilized (no.)Region and country

Yield testing Hybridization

East AsiaChina 5 48Taiwan (China) – 15

Southeast AsiaCambodia 54 4Indonesia 70 29Malaysia 10 1Myanmar 82 35Philippines 16 32Thailand 61 30Vietnam 10 13

South AsiaBangladesh 38 22India 81 83Nepal 9 –Pakistan 13 8

West Asia and North AfricaEgypt 16 42Iran 16 –Turkey 5 3

Latin AmericaColombia 5 –


fied to make it more reliable and easier to use. It wasalso modified to install the Texas–InternationalWheat and Maize Improvement Center (CIMMYT)interface for the ICIS CD release.

ICIS development

The plant breeding interface for ICIS comprisingSETGEN and FLDBK was redesigned and im-proved at IRRI in response to feedback from breed-ers. The new versions are easy to use, are quick, andlink to familiar Microsoft Excel outputs as well ascustomized field books. A prototype ICIS Work-book was developed at IRRI as a DMS input andquery tool, consisting of a series of Excel macrosthat access the DMS DLL.

A GMS input program was developed at IRRI todownload large sets of breeding cross histories andaccession lists. This tool facilitates the capture ofhistorical data in the development of new ICIS im-plementations. It was used to link IRIS to theSystemwide Information Network for Genetic Re-sources (SINGER) and to form a base imple-mentation for maize (International Maize Informa-tion System—IMIS) by downloading CIMMYTmaize accession genealogy from SINGER to ICIS.The GMS Browse program was improved to allowcalculation of coefficients of parentage, tracing theuse and distribution of genetic resources, and analy-sis of contributions of different sources to particu-lar lines.

IRRI hosted an ICIS Workshop for 43 partici-pants from CIAT, CIMMYT, the International

Center for Agricultural Research in the Dry Areas(ICARDA), the International Centre for Research inAgroforestry (ICRAF), IITA, IRRI, and the Interna-tional Service for National Agricultural Research aswell as NARS representatives from China, India,Korea, Philippines, Australia, France, and the USA.We verified that the DMS can store data from mo-lecular studies, and a start was made on the designof the Gene Management System to handle uniqueidentification, nomenclature, source, location, andfunction of genetic elements, including molecularpolymorphisms, sequences, and traditional genes.

IRIS development

Further capture of historical pedigrees has enlargedIRIS to more than 700,000 lines. Breeding recordsfrom Thailand (20,000), Malaysia (7,573), and Pa-kistan (4,939) were added. CIAT breeding records(5,000) were updated as well as IRGC and GRINrice accessions. Considerable effort went into veri-fying and correcting pedigrees for released varietiesas part of the Economic Evaluation of GermplasmImprovement Impact Study. There are now recordson 3,000 released varieties from 72 countries. His-torical characterization and evaluation data from thePlant Breeding, Genetics, and Biochemistry Divi-sion and the Genetic Resources Center were loadedinto the IRIS DMS—155 studies including the hy-bridization block data, observational yield trial data,and replicated yield trial data from 1977 to 1996.Characterization data for 65,315 genebank acces-sions have also been loaded, and response data from

Table 4. Genetic diversity of blast pathogen population of Pyricularia griseaafter 11 cycles of sequential plantings of mixed rice cultivars in differentcombinations. IRRI, 1999.

Treatmenta

Level 1 2 3 4

Hgb Hs Hg Hs Hg Hs Hg Hs

Lineage 1.1 0.8 0.5 0.6 1.0 1.0 1.1 1.1Pathotype 3.1 2.2 4.9 2.7 3.8 2.4 4.2 2.5Lineage-pathotype 3.5 2.3 3.2 1.4 4.5 2.6 4.8 2.6

Total isolatesc 17/28 9/27 18/30 15/28

a1= IR50, 2 = mixture of broadly susceptible varieties, 3 = six host cultivars, 4 = nine cultivars.bGenetic diversity indices: Hg = Gleason index; Hs = Shannon index. cIsolates used for lineageanalysis/isolates used for pathotype analysis.


two INGER nurseries (International Rice Soil StressNursery 1980-91 and International Irrigated RiceYield Nursery-Early 1984-96) were added to DMS.

IRIS is fully deployed in the irrigated rice breed-ing program at IRRI and is used by the Upland Per-ennial Rice Breeding project. It is also being de-ployed in the Rainfed Lowland Shuttle BreedingProgram. The features of IRIS that allow full par-ticipation in data sharing are ideal for managementof data from a shuttle-breeding program. However,the number of nodes in the network and their distri-bution make training and logistics difficult.

NARS partners in Cambodia, China, India, Indo-nesia, Laos, Philippines, and Thailand are interestedin using IRIS. Researchers from all those countrieshave been trained in various aspects of its use.China, Korea, Philippines, and Thailand have re-turned historical genealogy data and some countriesare now setting up local databases for use in man-aging breeding programs.

Seed health testing services

T.W. Mew S.D. Merca, P.G. Gonzales,C.C. Huelma, and J.O. Guevarra

The Seed Health Unit processed 59 incoming seedshipments from 22 countries for post-entry clear-ance (Table 5). Their consignment is shown in Ta-ble 6.

Post-entry examination showed that 32 ship-ments were contaminated with quarantinable ob-jects such as soil, insects, and weed seeds. Contami-nation with weed seeds was only 0.6%, mainlyEchinochloa sp. and Ischaemum rugosum. Seed lotsaffected by insects were 11.3%, mainly bySitophilus granarius and S. oryzae. Seed health tests

showed that Bipolaris oryzae affected 66% of theseed lots, followed by Microdochium oryzae (40%),Fusarium moniliforme (22%), Sarocladium oryzae(19%), Tilletia barclayana (14%), Aphelenchoidesbesseyi (2%), and Pyricularia oryzae (1%). Theprescribed ASEAN standard seed treatments wereapplied to all incoming seeds. Incoming seeds weremultiplied only in the designated post-entry area onthe Experiment Station and were monitored for crophealth.

Almost 13,000 entries were inspected for pre-export certification, of which 12% were affectedwith leaf scald, 6% with tungro virus, and 6% withbacterial leaf streak. In WS crop selection, seedlingblight affected 11% of the entries, leaf scald 73%,and bacterial leaf streak 25%.

Crop health inspections were made on 8,035 en-tries in the DS and 3,339 in the WS. The most com-mon DS disease was sheath rot, affecting 34% of theentries, while bacterial leaf streak affected 23%. Nodiseases were seen on 46% of the entries. Fewer dis-eases were observed in WS than in DS.

Table 5. Origin of incoming seed shipments to IRRI, 1999.

Region Countries Shipments Seed lots Weight (no.) (no.) (no.) (kg)

East Asia 3 19 3,552 34.5South Asia 4 8 92 40.9Southeast Asia 7 18 7,969 166.4Latin America 1 1 15 0.9North America 1 4 110 2.7Sub-Saharan Africa 3 5 344 36.1West Asia and North Africa 3 4 127 4.6 Total 22 59 12,209 286.1

Table 6. IRRI consignees of imported rice seed shipmentsin 1999.

Division Shipments Seed lots Weight(no.) (no.) (kg)

APPAa 5 1,249 15.9EPPDb 3 329 10.2GRCc

INGERd 10 78 22.1IRGe 13 3,491 120.8

PBGBf 28 7,062 117.1Total 59 12,209 286.1

aAgronomy, Plant Physiology, and Agroecology. bEntomology andPlant Pathology. cGenetic Resources Center. dInternational Networkfor Genetic Evaluation of Rice. eInternational Rice Genebank. fPlantBreeding, Genetics, and Biochemistry.


Phytosanitary certificates were issued for 426rice seed shipments covering 67,176 seed lots(1,975.5 kg) sent to 54 countries worldwide (Table 7).Routine seed health testing of 9,440 nontreated, out-going seed lots revealed that S. oryzae (sheath rot)affected 58% of the seed lots, followed by F.moniliforme (41%), B. oryzae (36%), M. oryzae(10%), T. barclayana (1%), P. oryzae (0.7%), andA. besseyi (0.3%).

All exported rice seeds were cleaned for quaran-tinable objects, tested for health, and treated withprescribed ASEAN standard seed treatment forrice—hot-water 52-57 °C/15 min. This was fol-lowed by fungicide slurry treatment with benomyland mancozeb both at 0.1% by seed weight, exceptfor countries that do not allow seed treatment.Fumigation with phosphine was also administeredto all outgoing seeds.

A database for the management of the SeedHealth Unit operations was developed in MS-SQL7.0. Researchers from Bangladesh (5), Cambodia(1), China (1), Indonesia (1) Lao PDR (1), Thailand

(1), and Vietnam (1) were trained in rice seed healthfor crop management.

Program outlook

Satisfying demand for information on germplasmand its characteristics and performance will be amajor challenge for the next year. We are workingto place the genebank database, IRGCIS, and IRISon the World Wide Web to permit interactive accessto germplasm data. We are evaluating differentways of improving the distribution and testing ofgermplasm through INGER. The SDC-fundedproject will terminate in mid-year, and much of thegermplasm collecting in many countries will becompleted by that date. Our biosystematic and ge-netic diversity studies continue to provide a frame-work for management and use of the wild species.Seed health testing protocols will continue to bemodified in response to demands from plant quar-antine authorities around the world.

Table 7. Distribution of rice seed shipments with phytosanitary certification bythe Seed Health Unit, IRRI, 1999.

Region Countries Shipments Seed lots Weight(no.) (no.) (no.) (kg)

East Asia 5 101 14,517 425.8South Asia 6 97 13,496 483.1Southeast Asia 9 95 14,774 487.4Europe 11 44 1,933 133.0Latin America 8 16 1,743 57.1North America 2 23 10,614 156.2Oceania 1 10 2,563 15.8Sub-Saharan Africa 8 20 2,628 62.1West Asia and North Africa 4 20 4,908 155.0

Total 54 426 67,176 1,975.5

Accelerating the impact of rice research

STRENGTHENING PARTNERSHIP WITH NARS 120Institutionalization of rice research in Cambodia 120Rice research in the Lao PDR 121

DELIVERY OF KNOWLEDGE-INTENSIVE TECHNOLOGIES: CROP AND RESOURCE MANAGEMENTNETWORK (CREMNET) 122Paddy drying practices and evaluation of a simple dryer 122

Bangladesh 123India 123Myanmar 123

Farming systems technology in Cambodia 123

COLLECTING, EXCHANGING, AND DISTRIBUTING KNOWLEDGE AND INFORMATIONABOUT RICE 124Scientific publishing 125Public awareness 125IRRI visitors, exhibitions, and conferences 126Library and documentation service 126

HUMAN CAPITAL DEVELOPMENT OF NARS RICE PROFESSIONALS 126Degree and postdegree training 126

Language proficiency development for scholars and trainees 126Development and implementation of short-term group courses 129Development of new training methodology 129Training materials development 130Collaborative in-country training 132

Regional courses 132National courses 132

PROGRAM OUTLOOK 132International Programs Management Office (IPMO) 132Training Center 132CREMNET 132Access to IRRI's media assets 133Computer Services 133


Accelerating the impact of rice research

Strengthening partnership with NARS

The need for strengthening of NARS in Asia is de-clining and IRRI focuses on technical support andtraining in strategic research areas for the advancedNARS. For NARS at an earlier stage of develop-ment, IRRI provides technical support for strength-ening national research infrastructure, with fundingderived mainly from bilateral sources.

Institutionalization of rice research inCambodiaH.J. Nesbitt

Agricultural research in Cambodia received re-newed attention over the past decade. Thirty-fournew rice varieties were released, an agronomicbased soil identification system was developed, andrecommendations extended to improve soil produc-tivity. Pest prediction tables and control recom-mendations using integrated pest management(IPM) techniques adapted to local conditions werereleased. Farming systems techniques, includingagricultural engineering, to improve overall farmproductivity were developed and extended.

These research programs were implementedwithin a framework of improving resources, espe-cially in human capital. The Cambodia-IRRI-Aus-tralia Project (CIAP) played a significant role, train-ing 1,128 individuals between 1987 and 1998, witheach person attending an average of three courses.Thirteen project participants either completed or arein the process of fulfilling the requirements for PhDor MS degrees in Australia.

Concurrent improvement in the physical infra-structure of research stations over the past 10 years

The impact of rice research on low-income riceproducers and consumers is our foremost concern.The ability to make positive and lasting contributionsto poverty alleviation, food security, and sustainablemanagement of natural resources depends on two keyfactors:

● quality and relevance of research, and● effective evaluation, adaptation, and delivery of

research products to clients/users.Accelerating the Impact of Rice Research (IM)

takes results from research programs, works thoseinto usable technologies, evaluates the technologies,and adapts them to specific rice-growing conditions incollaboration with national agricultural researchsystems (NARS). Technical support and infrastructurestrengthening are provided to NARS. IM has fourprojects:

● Strengthening partnership with NARS● Delivery of knowledge-intensive technologies:

Crop and Resource Management Network(CREMNET)

● Collecting, exchanging, and distributingknowledge and information about rice

● Human capital development of NARS riceprofessionals

Accelerating the impact of rice research 121

facilitated the installation of research trials. That in-frastructure, and some research, was assisted by anumber of nongovernment organizations (NGO)and the United Nations. All agencies work in closecollaboration with the Cambodian Ministry of Ag-riculture, Forestry and Fisheries (MAFF). About200 of 11,500 MAFF staff members work in agro-nomic research under the Department of Agronomy(DOA). Their research is supported by a central ad-ministrative office, a soils laboratory, and a plantprotection center. The DOA has 14 research centersthat cover a range of crops.

A new agricultural research and extension policywas adopted by the MAFF in August 1999. Re-search and extension became separate functions ofMAFF and will soon have separate budget alloca-tions. An Agricultural Research Council (ARC) willoversee the direction and monitoring of researchinstitutes. Research institutes will be semi-autono-mous with a charter of responsibilities under the di-rection of the ARC. Technical departments will beresponsible for production, statistics, regulation,surveillance, compliance, and technicalbackstopping for the provinces.

The newly formed Cambodian Agricultural Re-search and Development Institute (CARDI) wasdesigned to fit into the new system to take primaryresponsibility for rice-based farming systems re-search in addition to overseeing upland crops, for-age crops, and horticulture research.

The research priority-setting process had consid-erable activity during 1997-99. Setting a charterunder which CARDI will operate was initiated andthe charter will be developed further in 2000 tospecify the nature and scope of the institute. CARDIwill receive support from

● government (staff and laborer salaries, opera-ting costs);

● foreign donors (infrastructure, salary support,technical assistance);

● international institutes (technical assistance,collaborative research funds, knowledge andinformation databases); and

● private sector (contract research, levies andresearch equipment).

CARDI and other semi-autonomous instituteswill receive overall direction from the ARC andthrough MAFF and a Board of Directors.

CARDI now has the physical and personnel re-sources plus the institutional support to carry itselfinto the 21st century. The institute is expanding itsfunding base to cover operational costs for anotherdecade.

Rice research in the Lao PDRJ. Schiller

Rice is the single most important crop in the LaoPDR, occupying more than 80% of the cropped areaand accounting for 80% of the caloric intake of peo-ple in rural areas. Most of the planted area is rainfed,which makes rice production highly susceptible toclimatic variations. Significant levels of rice deficitexist in some areas, particularly in the upland envi-ronment.

The Swiss Agency for Development and Coop-eration (SDC)-funded Lao-IRRI Project was initi-ated in 1990 to address rice research, development,and training. Almost 95% of the rainfed lowlandand 100% of the uplands were being planted to tra-ditional varieties and there was no defined nationalrice research program. The level of fertilizer inputswas also low. Yields in the lowlands often did notexceed 2 t ha–1.

By the end of 1999, with the cooperation of theMinistry of Agriculture and Forestry and provincialagriculture and forestry offices, a rice research net-work had been established throughout the country.Seven research centers serve the central, southern,and northern agricultural regions. Research activi-ties are coordinated by the National AgriculturalResearch Center (NARC) located in Vientiane Mu-nicipality. At the end of 1999, more than 130 coor-dinators, scientists, and technicians were collaborat-ing in the national rice research network and a Na-tional Agricultural Training Center had been estab-lished at NARC.

The national rice research network includes va-rietal improvement, germplasm conservation, soilfertility management, plant protection (IPM andweed research), agronomy, seed technology, andintegrated production systems research. The alloca-tion of resources and related research emphasis isdivided among the three rice environments at about60% for rainfed lowland, 25% for irrigated, and15% for upland rice.


Improved rice varieties (with mostly IRRI par-entage) contributed to more than 80% of productionin the rainfed lowland in 1999. All Lao improvedvarieties are glutinous. Soil fertility research hasdeveloped fertilizer recommendations for therainfed lowland and irrigated environments. Farm-ing systems research has demonstrated the benefitsof adopting an integrated package of technical rec-ommendations in rainfed lowland.

Training has been a major part of the Lao Na-tional Rice Research Program. By the end of 1999,more than 1,070 places had been provided in vari-ous types of in-country training, including Englishlanguage studies. Lao language versions of IRRInondegree training on Basic Rice Research andFarming Systems Research were developed andadopted to local needs. A total of 197 NARC staffmembers were supported in various kinds of non-degree training and special work experience at IRRIand in third countries during 1990-99. Five researchstaff members either completed or are in the proc-ess of completing their MS studies.

Constraints still being faced in relation to thesustainability of the Lao National Rice ResearchProgram include the need for

● greater Lao leadership of the program;● improved systems for monitoring, evaluation,

and review; and● development of a greater critical mass of

trained staff such that the effect of the move-ment of individual staff on the researchprograms is minimized.

The upland component of the research programhas yet to develop technical recommendations thatcan achieve the objectives of food security, reduc-tion of income disparities, and ecological stabili-zation of upland areas. Further development of thenational extension services is also essential to maxi-mize the potential benefits of research to small-scaleproducers.

Delivery of knowledge-intensivetechnologies: Crop and ResourceManagement Network (CREMNET)

Rice production technologies are becoming morelocation-specific, complex, and knowledge-inten-sive as crop intensification achieves high yields (8-10 t ha-1) in farmers’ fields. CREMNET is designedto facilitate the identification, free exchange, parti-cipatory evaluation, and promotion of promisingrice farming technologies.

Paddy drying practices and evaluationof a simple dryerV. Balasubramanian, A.C. Morales,M.A. Baqui,20 Myint Wai,40 and S. Hooper41

Drying of harvested rough rice (paddy), especiallyduring rainy season, is a major problem for rice pro-ducers in many Asian countries. More than 80% offarmers sun-dry paddy on open floors with highlosses in quantity and quality of grain. Many farm-ers lack drying floors and use public roads to drypaddy. Farmers need a simple, low-cost dryer to drypaddy economically and efficiently.

The University of Agriculture and Forestry(UAF), Vietnam, participated during 1994-95 in atechnical cooperation project with IRRI and the do-nor agency, German Agency for Technical Coope-ration, Germany, to develop a low-cost, low-tem-perature dryer called the SRR-1. It can dry 1 t ofpaddy in 2–3 d, with the same unit used as storage.Targeted users are resource-poor farmers with lessthan 0.5-ha rice land and who need to store 1–2 tpaddy each season.

The dryer consists of a 1/2-hp, two-stage axialfan, a 1000-watt electric heater, and a drying bin ofbamboo mat or other material. The drying bin hastwo concentric bamboo-mat cylinders of 0.4 m and1.5 m diameter, with a height of 1.1 m. The innercylinder is supported by a frame made of 6-mmsteel wire. A 0.5-hp, single-phase, 2800-rpm elec-tric motor drives the fan. Two 350-mm-diameter,seven-blade plastic rotors are mounted on both endsof the motor shaft and enclosed in a steel-wire cas-ing. The fan is positioned on top of the inner bam-boo-mat cylinder. At 40 Pa static pressure, the air-flow is 0.3 m3 s–1.


The heater is a 1000-w resistor from an electricstove, mounted beneath the motor. Supplementalheat from the resistor is used at selective times—e.g., cool nights or during continuous rains. TheSRR-1 dryer costs US$55 in Vietnam, and the cal-culated drying cost is US$6 t–1.

We surveyed the paddy drying practices in se-lected areas in Bangladesh, India, and Myanmar ina collaborative project with UAF and NARS. Localengineers and technicians, with the help of UAFengineers, built and commissioned a prototypedryer in each area and collected users’ feedback forfollowup action.

BANGLADESH

Selected Bangladesh villages of Sylhet andChittagong districts were surveyed. About 54% ofthe sample farmers were educated above secondaryschool level and 83% had the national medium levelof income. Only 27% of total income came fromagricultural sources. Almost all farmers had a land-holding of less than 2 ha and mean rice yield was 3t ha–1. All farmers used the traditional methods ofrice harvesting with sickles, manual threshing, andsun drying. About 65% of the farmers reported adrying loss of 1–3%, and 95% expressed the needfor a simple mechanical dryer.

Respondents stored paddy for 1–7 mo. Mostfarmers (82%) sold their paddy in different lots 1–4mo after harvest.

Pilot testing of the SRR-1 dryer was conductedat the Bangladesh Rice Research Institute station,Gazipur. The cost of the locally manufactured dryerwas US$117 and the drying cost was US$6.57 t–1

paddy. The head rice recovery was higher for paddydried in the dryer than for sun-dried paddy. Farm-ers, extension workers, farm machine manufactur-ers, and rice millers witnessed the dryer demonstra-tion. Ten dryers were produced in 1998 for tests anddemonstrations in 1999 and 2000.

INDIA

Three villages in Pondicherry State, India, were sur-veyed. Farmers faced difficulties in drying rice har-vested in wet weather in September. Many farmerssell excess paddy immediately after harvest. Mostof the farmers sun-dried paddy for home consump-

tion on hard mud-plastered surfaces near the home-stead or sometimes on public roads.

The SRR-1 dryer was installed on a farm atSivaranthakam village and the drying of wet paddywas demonstrated to about 100 farmers assembledfrom nearby villages. One SRR-1 unit was given tothe LAM Research Institute, Andhra Pradesh, fortesting and demonstration to farmers in the coastaldistricts of Andhra Pradesh where drying is a seri-ous problem for rice harvested in wet season.

MYANMAR

A survey covered six villages from five townshipsin Yangon and Bogo divisions. Among farmers inthe study area, landholding ranged from 2.4 to 5.8ha, with a mean of 4.1 ha. Farm income constituted87–100% of the total income.

Harvested paddy is kept on the threshing floorfor 5–10 d before threshing, a practice that can ad-versely affect grain quality and head rice recovery.About 70% of the farmers use hired mechanicalthreshers. The machine threshing requires about 4 hha–1 at a cost of US$10 ha–1.

Traditional sun-drying of rice is predominant.About 13–15 workers ha–1 are employed for sun-drying at a cost of US$6.85–7.17 t–1. The estimateddrying loss is 3.0–4.3%. The dried paddy is storedin bamboo bins for 3-5 mo.

The dryer was demonstrated to farmers, engi-neers, and technicians of the Agricultural MachineManufacturers Cooperative. The farmers preferreda high-capacity, village-level dryer. Moreover, elec-tricity to operate the SRR-1 dryer is not available invillages.

Farming systems technology in CambodiaC. Phaloeun, T. Vuthy, S. Sakkhunthea,and H.J. Nesbitt

Constraints to rice production in Cambodia are re-lated to infertile soils, poor on-farm water control,pest incidence, and low-yielding indigenous varie-ties. The CIAP has developed soil fertility improve-ment recommendations for each soil group, appro-priate land leveling and on-farm water conservationtechniques, and environment-friendly pest controltechniques that decrease crop damage and reduceproduction costs.


Project plant breeders have released a range ofvarieties suitable for most of the rice-growing envi-ronments in Cambodia. Farming systems agrono-mists have combined these technologies into pack-ages to evaluate in farmers’ fields. A study during1996-99 compared the technology packages withfarmers’ practices on recession (partially irrigated)and rainfed lowland rice grown in a series of soiltypes and water depths.

CIAP technology increased yields in the rainfedlowland ecosystem by as much as 140% based oncomparisons with neighboring farms. Farmers re-ceived an average 69% additional net income byusing CIAP technology if the cost of the landleveling was not included and if loans were not nec-essary to purchase inputs. It is, however, necessaryfor the farmer to increase the level of purchased in-puts to adopt the technology, thus increasing eco-nomic risk.

Farmers were surveyed twice during the growingseason to monitor farm activities, labor use, andcash flows. Cash values were placed on home-pro-duced and -consumed products by surveying theirpotential value at local markets. Off-farm incomewas calculated on a family basis and, in some cases,included the sale of gold or other valuables. Expen-ditures were composed of farm, off-farm, andhousehold and hired labor. Family farm labor wasnot charged to the budget.

Major farm activities of all farms were culti-vation of rice and attending to cattle. Time was alsospent on caring for other animals, nonrice crops, andcatching fish in rice fields and nearby streams. Fourof the farms surveyed raised fish on their properties.Working persons constituted just over half of thefamily members and each worked on the farm foran average 100 d y–1.

Farm sizes ranged from 0.9 to 3.8 ha with an av-erage of 1.7 ha. Household sizes were 1.5 personsabove the national average of 5.5, making it diffi-cult for the smaller farms to produce surpluses forsale. The 12 farms averaged net cash incomes of$254 in 1 year, with income ranging from a loss of$31 to an income of $914. Two-thirds of the farmsreceived off-farm incomes. These were usuallyfrom off-farm labor or small businesses. Farm in-come was regularly derived from the sale of rice butsale of pigs or other animals, including fish, was themajor cash income source.

Except in those cases where the farmers hadsmall businesses, household costs consumed a ma-jor proportion of the cash income. Only a smallamount of money was spent on purchasing farm in-puts each year. Surplus funds were generally usedfor medicine or school fees. Where off-farm acti-vities were minimal, net income was extremelysmall or negative.

Nine of the 12 farm families were highly depend-ent on farm-grown products, foraging, and fishing.The average value of food produced or gathered orcaught near the farm exceeded the net cash incomeby about 50%.

The study emphasizes the high degree of risk thefarmers in southeastern Cambodia face if their cashincome or subsistence product levels are destabil-ized. It is important that one farm component is notimproved at the risk of decreasing overall farm pro-ductivity. The development of technology suitablefor these farmers must take into consideration thelow levels of household cash income and the factthat they are dependent on home-produced goodsfor survival. Acceptance of new technology formany farmers will be a gradual process with thelow-cost technologies being adopted first and dif-ferent approaches being taken to reduce input costs.Other farmers may opt to work off-farm to purchasethe technology they believe will provide sustainablefarm productivity increases.

Collecting, exchanging, and distributingknowledge and information about rice

G. Hettel, B. Hardy, D. Macintosh,S. Inciong, M. Ramos, M. Movillon, and staff

IRRI’s mandate requires that the Institute publishand disseminate research findings and promote cur-rent rice research knowledge to scientists world-wide. Activities include

● publishing and disseminating high-quality sci-entific materials about rice;

● promoting IRRI and rice research throughpublic awareness activities;

● maintaining the IRRI Library and Docu-mentation Service as the world’s foremostcollection of materials on rice;

● maintaining and further developing the Rice-world Museum and Learning Center; and


● taking advantage of new information deliverytechnologies, particularly in the area of elec-tronic communication media, to speed theexchange of information among rice scientistsworldwide.

Scientific publishing

IRRI’s four web sites—the IRRI Home site(www.cgiar.org/irri), Riceweb, Riceworld, and theIRRI Library site—continue to grow in popularity.There were nearly 120,000 visitors to our web sitesduring 1999. They made more than 500,000 hits ormovements within the sites.

The web sites were improved by addition of elec-tronic versions of

● 1999 issues of the International Rice ResearchNotes (www.cgiar.org/irri/irrn.htm),

● the 1998 Program Report (www.cgiar.org/irri/98programreport.htm),

● INGER-derived rice varieties (www.cgiar.org/irri/INGERforeword.html),

● popular discussion papers,● the Medium-Term Plan 2000-2002,● IRRI’s monthly newsletter Sandiwa

(www.cgiar.org/irri/Sandiwa.htm), and● abstracts of recent IRRI conference and work-

shop proceedings (www.cgiar.org/irri/absidx.htm).

More than 200 direct links to useful web siteswere added to the Library web site.

Improvements continued to the in-house IRRIIntranet. Several Intranet sites, created by IRRI’sdivisions, centers, units, programs or research net-works, were elevated to the external Internet—ge-netic resources (www.cgiar.org/irri/geneticresources.htm),Asian Rice Biotechnology Network (www.cgiar.org/irri/ARBN/arbnindex.htm), and the Systems ResearchNetwork for Ecoregional Land Use Planning inTropical Asia (www.cgiar.org/irri/sysnet/index.htm).

Credit card sales of IRRI books continued suc-cessfully on the Internet via the German vendorTRIOPS.

Twenty-five titles were produced and distrib-uted, including six IRRI books, eight installments ofthe IRRI discussion paper series, six installments ofthe new technical bulletin series, and one install-ment of the new limited proceedings series. One ofthe books, A rice village saga: three decades ofgreen revolution in the Philippines, was a triple im-

print with Macmillan Press Limited and Barnes &Noble. A bibliography is provided in the section onpublications and seminars near the end of this pro-gram report. The 25-year-old International Rice Re-search Notes (IRRN) was given a fresh new formatwith expanded features and sections.

More than 1,100 h of historic videotapes wereindexed, work that will continue into the IRRI stillphotography collection in 2000. With an appro-priate search engine, IRRI staff and clients will thenbe able to search for available photos and videos onCD.

Staff members in Communication and Publica-tions Services received one Outstanding Profes-sional Skill Award, three Gold Awards, and oneBronze Award at the 1999 meeting of the U.S.-based Agricultural Communicators in Education asrecognition of outstanding skills in writing, photo-graphy, and graphic design in publications and websites.

Public awareness

A new head of public awareness (PA) arrived inMay. New initiatives focused on donor organiza-tions, the international media, and other key audi-ences, including IRRI’s local community.

In August, the PA Unit launched The IRRI Hour,a three-times-a-week chat and music program onthe FM radio station on the campus of the Univer-sity of the Philippines Los Baños. Many IRRI sci-entists have been local radio guests.

PA arranged 25 radio or television interviews inwhich IRRI scientists appeared before internationalaudiences. About 60 news releases and more than100 photographic releases were issued to the worldnews media during the year, covering research de-velopments, new appointments, important visitors,and major conferences.

Four issues of the Hotline newsletter wereprinted and distributed.

PA helped organize 19 special events, includingNGO, Host Country, and Ambassador days. PAalso arranged the first corporate sponsorship of anIRRI event during which the airline Lufthansa spon-sored a week-long IRRI-Germany event in Novem-ber. The PA unit will continue seeking corporatesponsorship to carry word of IRRI achievements tothe international public.


IRRI visitors, exhibitions, and conferences

1999 was an active year for international exhi-bitions. IRRI staff members staged eight inter-national displays, and one in the Philippines, includ-ing first-ever appearances at the World Bank annualconference in Washington and the American Soci-ety of Agronomy meeting, as well as the week-longIRRI-Germany event.

A fire in Chandler Hall in September extensivelydamaged the popular Riceworld Museum andLearning Center, depriving IRRI of its principalshowpiece for visitors. Renovations began immedi-ately to the fire-, smoke-, and water-damaged mu-seum and a new, updated Riceworld was ready forIRRI’s 40th anniversary celebration in April 2000.

Four months without Riceworld and the Chan-dler Hall auditorium reduced the number of visitorsin 1999. Despite the disruption, more than 38,250people visited IRRI, including a royal head of state,8 state ministers, 39 ambassadors and members ofthe diplomatic corps, and 11 representatives of vari-ous international and donor organizations.

IRRI sponsored or cosponsored and hosted 24regional and international conferences, workshops,symposia, reviews, and meetings, attended by morethan 1,150 participants from 48 countries (Table 1).

Library and documentation service

During 1999, 7,445 references were added to therice bibliography at the IRRI Library, bringing thetotal to nearly 180,000. One hundred four disserta-tions, mainly from China and the Philippines, wereacquired.

The library’s computer equipment was upgradedto scan and transmit documents via email. An au-diovisual learning center was opened at the libraryfor use by the IRRI staff.

Plans were announced for expansion of the li-brary’s rice database and its online public accesscatalog, and for placing 50 year of citations from itsRice Literature Update on CD-ROM.

Human capital developmentof NARS rice professionalsR. Raab and staff

IRRI’s training efforts anticipate, and respond to,the needs of rice research and development pro-grams. It simultaneously addresses the human re-source development needs of NARS and the objec-tives of IRRI in fulfilling its global mandate.Between 1961 and 1999, IRRI’s training programprovided 12,439 opportunities for degree andpostdegree scholarships, and headquarters and in-country group training. That training benefitedNARS rice scientists and professionals from 98countries.

Degree and postdegree training

The objective of degree and postdegree training isto increase the number of highly trained profession-als in NARS institutions and develop leaders in ricescience. In 1999, a total of 130 rice scientists from19 countries participated in the degree andpostdegree training program: 74 PhD scholars, 23MS scholars, 22 on-the-job (postdegree) fellows,and 11 interns (Table 2). Fifty-five scholars and fel-lows completed their program during the year: 22PhD scholars, 7 MS scholars, 21 on-the-job fellows,and 5 interns (Table 3).

LANGUAGE PROFICIENCY DEVELOPMENT FOR

SCHOLARS AND TRAINEES

Scholars and trainees require a good level of profi-ciency in the English language for success in learn-ing. During 1999, we offered four language profi-ciency development courses: Basic English, Self-editing, Conversational English, and English forAgriculture. Sixty-three individuals from 13 coun-tries, including scholars, trainees, IRRI staff mem-bers, and some spouses, participated in the courses.The English as a Second Language (ESL) lab pro-vided a parallel service for those who had individualprogrammed lessons. Six graduating scholars hadassistance in the editing of their thesis manuscriptsfor grammar and style.


Table 1. International and regional conferences, workshops, symposia, and meetings hosted or cosponsored by IRRI,1999.

Participants CountriesDate Title Venue (no.) (no.)

11–22 Jan Workshop on Data Analysis of the Participatory IRRI 10 1Plant Breeding Project

7–16 Mar SysNet Workshop on Methodologies for India 31 5Land Use Planning for Haryana State, India

8–12 Mar International Crop Information System IRRI 43 13(ICIS) Development Workshop

7–12 Apr SysNet Workshop on Analysis of Land Use Malaysia 51 5Scenarios for Kedah-Perlis Region, Malaysia

15–16 Apr Mid-Term Meetings of the Agricultural IRRI 29 3Technology and Utilization and Transfer (ATUT)

16–19 Apr SysNet Workshop on Methodologies for Land Vietnam 45 4Use Planning for Can Tho Province, Vietnam

19–22 Apr Workshop on Carbon and Nitrogen IRRI 25 8Dynamics in Flooded Soils

21–26 Apr The Red River Basin Ecoregional Project(RRBEP) Vietnam 28 2Regional Working Group Meeting andTechnical meetings

21–24 Apr Rice Orientation Workshop for News Media IRRI 24 9

3–12 May Pest Impact Assessment Research: Workshop on India 25 6Data Management and Analysis; Discussion on“Red Stripe” Disease, and visit to IRRC site

7–12 May Workshop on Analysis of Land Use Scenarios Philippines 57 4for Ilocos Norte and Stakeholders’ Meeting

12–14 May Bioinformatics Workshop IRRI 14 5

24–26 May Workshop on Geo-Information Techniques for India 50 2Understanding and Analyzing Rainfed RiceEnvironments in Eastern India

9–12 Aug Third Working Group Meeting and Review IRRI 49 9of the Project on Assessing Opportunities forNitrogen Fixation in Rice

23–27 Aug Second CREMNET-India Workshop Cum Group India 52 8Meeting on Innovative Nitrogen and Other CropManagement Technologies for Intensive RiceSystems of South Asia

24–27 Aug Workshop on Genebanks and Comparative Genetics Netherlands 52 21

6–10 Sep Workshop on Decision Processes for Determining Philippines 54 20Diagnostic and Predictive Criteria for Soil NutrientManagement

28–29 Sep PhilRice-UPLB-IRRI Tripartite Meeting IRRI 75 1

5–7 Oct Human Nutrition Workshop IRRI 93 20


Table 1 continued.

Participants CountriesDate Title Venue (no.) (no.)

11–13 Oct SysNet 99: Systems Research for Optimizing IRRI 75 8Future Land Use

11–14 Oct Upland Rice Research Consortium Steering and India 50 11Technical Committee Meeting

26–29 Oct Planning Workshop on Ecoregional Approaches Thailand 50 3to Natural Resource Management in theKorat Basin, Northeast Thailand

17–19 Nov Workshop on Seed Health for Disease Management Thailand 41 10

27–28 Nov Council for Partnership on Rice Research Thailand 19 11

29 Nov.–3 Dec Redesigning Rice Photosynthesis Workshop IRRI 25 6

5–9 Dec International Workshop on Understanding and Indonesia 70 10Characterizing Rainfed Environments

10 Dec 10th Rainfed Lowland Rice Research Indonesia 15 5Consortium Steering Committee Meeting

Samejima, Hiroaki JapanAndrianilana, Fidelis J. MadagascarRamanantsoanirina, Alain Mari MadagascarRazafinjara, Aime Lala MadagascarHtet, Kyu MyanmarHtut, U Tin MyanmarThet, Khin Maung MyanmarWinn, Tun MyanmarBhandari, Hum Nath NepalOjha, Gana Pati NepalRegmi, Anant Prasad NepalTrolove, Stephen Neil New ZealandArif, Muhammad PakistanFaiz, Faiz Ahmad PakistanHussain, Fayyaz PakistanIjaz, Muhammad PakistanBriones, Lucia M. PhilippinesCabuslay, Gloria Philippinesdelos Reyes, Jeannelyn B. PhilippinesEnriquez, Emilie C. PhilippinesLumbo, Susanita G. PhilippinesRubia, Leila G. PhilippinesMnzava, Moses N.W. TanzaniaLersupavithnapa, Boontium ThailandLinwattana, Grisana ThailandNieuwenhuis, Pailin ThailandGraw, Stephen M. United StatesCuong, Ngo Luc VietnamHuu Ho, Nguyen VietnamLe, Cam Loan VietnamLe, Thi Phuong VietnamNghia, La Tuan VietnamNgo, Ngoc Hung VietnamNguyen, My Hoa VietnamNguyen, Van Hong VietnamThanh, Duong Ngoc Vietnam

PhD scholarsAlam, Muhammed Murshedul BangladeshAlam, Murshed BangladeshCui, Kehui ChinaFu, Binying ChinaJianli, Wu ChinaLi, Luping ChinaLiu, Bin ChinaLu, Wenjing ChinaXu, Jianlong ChinaYuequi, He ChinaZhong, Daibin ChinaZhong, Xuhua ChinaZiqi, Wang ChinaBagali, Prashanth G. IndiaBaisakh, Niranjan IndiaDeka, Nivedita IndiaDey, Moul IndiaKaur, Jatinder IndiaLourdusamy, Gabriel Stephen IndiaMathan, Natarajan IndiaMitra, Sudip IndiaNarayanan, Narayanan N. IndiaNath, Palash Deb IndiaRangan, Latha IndiaSreevidya, V.S. IndiaAbdullah, Buang IndonesiaMuhsin, Muhammad IndonesiaEsfahany, Masoud IranFallah, Allahyar IranHosseini Salekdeh, Seyed G. IranMoradi, Foad IranMoumeni, Ali IranKobayashi, Sohei JapanNaoyoshi, Kawano JapanOkada, Kanako Japan

Table 2. Participants in degree and postdegree training at IRRI, 1999.


Thi Ut, Tran+A26 VietnamTran, Chi Thien VietnamTruong, Van Tuyen Vietnam

MS scholarsJensen, Morten DenmarkShoatatek, Negussie EthiopiaSingh, Bhupinder Pal IndiaVarghese, Pulickal A. IndiaSattarai, Majid IndonesiaSuganda, Husein IndonesiaWidowati, Ladiyani Retno IndonesiaChung, Dae-Hwan KoreaInthavong, Soulaphone Lao-PDRRakotomalala, R. Mbolarinosy MadagascarBhattarai, Kiran NepalJoshi, Madan Raj NepalUpadhyay, Bhawana NepalDe Vries, Sander C. NetherlandsAlcantara, Jovencio PhilippinesAvendano, Bita S. PhilippinesMadamba, Reina Suzette B. PhilippinesPantua, Sheila Marie E. PhilippinesUlat, Victor Jun PhilippinesNgo, Dang Phong VietnamNguyen, Thi Phong Lan VietnamThach, Thi Ngoc Anh VietnamThao, Hoang Thi Bich Vietnam

Postdegree on-the-job traineesHossain, Shahadat BangladeshRahman, Shamsur BangladeshBounphanousay, Chay Cambodia

Table 2 continued.

Development and implementation of short-term group courses

Specialized short-term group training courses assistNARS professionals in increasing their competen-cies in rice science and in disseminating appropri-ate technology to end-users in NARS. Ten grouptraining courses were conducted in 1999, with par-ticipation by 95 scientists from 18 countries (Table4). Two of the courses were offered for the first timein 1999:

● Modern Rice Farming for Asia● Transgenic Rice Production and Deployment

with Special Reference to Sheath Blight andStem Borer Resistance

Development of new training methodology

We continued to improve our distance educationcapability. A 3-d meeting on the use of informationcommunication technology (ICT) in support of thetraining program was organized. Thirteen distance

Mot, Sana CambodiaPao, Sinath CambodiaNath, Palash Deb IndiaSikdar, Samir Ranjan IndiaPrasetiyono, Joko IndonesiaAdachi, Shimpei JapanKi-Do, Park KoreaBoualaphan, Chanthakhone Lao-PDRKhangsuthor, Khamdok S. Lao-PDRShrestha, Sundar M. NepalPedrera, Maria Jehan G. PhilippinesParakam, Jagkrit ThailandSengpaseuth, Rasabandith ThailandUrairong, Hathairat ThailandCuong, Nguyen Minh VietnamLuo, Wen Yong VietnamLuu, Van Quynh VietnamPhan, Van Tuan VietnamTran, Duc Thach Vietnam

InternsManio, DeniseChung, Carrie LeeGolinowsky, Shawn Paul AustraliaGray-Donald, James CanadaScholosser, David CanadaSchaffer, Sebastian CanadaWidharto CanadaDe Ponti, Tomek GermanyOort, Pepjin IndonesiaPonsioen, Thomas Christian NetherlandsRiksen, Barbara Netherlands

education and ICT experts from the US, UK,Canada, Japan, India, Thailand, the Philippines, andorganizations such as the World Bank, Common-wealth of Learning, and the International Develop-ment Research Centre (IDRC), attended and pro-posed strategies to upgrade the IRRI ICT capabil-ity.

Development of the IDRC-funded project Appli-cation of Distance Learning Technologies to Hu-man Capital Development continued. Simon FraserUniversity finalized the design for the online courseon Experimental Design and Data Analysis and isdeveloping its components. IRRI and the Directo-rate for Rice Research, Hyderabad, India, identifiedtwo priority online courses for their scientists: Dig-ital Literacy and Presentation Skills for Scientists.The online course on digital literacy was developed.The course on presentation skills was designed andcontent is being developed.

We used net-based video conferencing for re-mote delivery of topics to participants in a Rice Pro-duction Research course in Thailand. It was also


Table 3. Number of scholars and postdegree trainees who completed training atIRRI in 1999.

Type Ia Type IIa Type IIIa

CountryPhD MS PhD MS ND interns Total

AfricaMadagascar 0 0 2 0 0 2

Subtotal 0 0 2 0 0 2

AsiaAustralia 0 0 0 0 1 1Bangladesh 0 0 1 0 2 3Cambodia 0 0 0 0 3 3China 2 0 0 0 0 2India 4 0 0 0 1 5Indonesia 0 0 0 0 1 1Iran 1 0 0 0 0 1Japan 1 0 0 0 1 2Korea 0 1 0 0 1 2Lao-PDR 0 0 0 1 2 3Myanmar 0 0 1 0 0 1Nepal 1 0 0 0 1 2Pakistan 0 0 1 0 0 1Philippines 2 3 0 0 1 6Thailand 0 0 1 0 3 4Vietnam 3 0 1 2 5 11

Subtotal 14 4 5 3 22 48

EuropeGermany 0 0 0 0 1 1Netherlands 0 0 0 0 1 1New Zealand 1 0 0 0 0 1

Subtotal 1 0 0 0 23

North AmericaCanada 0 0 0 0 2 2

Subtotal 0 0 0 0 2 2 Total 15 4 7 3 26 55

aType I = MS and PhD scholars, thesis research only at IRRI. Type II = MS and PhD scholars,coursework and thesis at IRRI. Type III = on-the-job nondegree trainees and interns.

used for an interactive lecture by a resource personat Nanyang University, Singapore, to participants ina bioinformatics course at IRRI.

Training materials development

Training materials development supports groupcourse implementation, both at IRRI and in-coun-try. Twelve sets of training materials were producedin 1999:

● five course and reference manuals for threenew headquarters courses: Application ofMolecular Tools to Study Rice Viruses, Trans-genic Rice Production and Deployment, andSoil and Water Biochemistry and Ecotoxi-cology;

● two instructional video materials on the leafcolor chart (LCC) and the portable chlorophyllmeter;

● three Web publications based on print orsound-slide presentation formats of thetraining module on Growth Stages of the RicePlant, the course manual for the Trainers’Training Course, and the skills developmentbooklet How to Take Notes; and

● two manuals on tungro disease identificationand management to support a two-level coursefor field technicians and for farmers.


Hybrid Rice Breeding1 Mar–23 AprHaque, Md. Azizul BangladeshEl-Mowafi, Hamdi Fetouh EgyptKanwar, Omvir S. IndiaMutchukota, Subba Rao IndiaMaibam, Rohinikumar S. IndiaMukherjee, Sumita IndiaLekkala, Madan Mohan Reddy IndiaKitani, Shigekazu JapanKaskon, Mohd. Asrore Bin MalaysiaAye, Mar Mar MyanmarCheema, Md. Bashir Pakistandela Rosa, Analen M. PhilippinesGaspar, Manuel G. PhilippinesSilva, Jayasena T. Sri LankaDao, Thi Phuong Vietnam

Introduction to IRRISTAT Statistical Software1 Mar–23 AprRoongrawee, Puttana ThailandTacho, Chonticha Thailand

Modern Rice Farming for Asia3–28 MayRahman, Habibur BangladeshUddin, Md. Mahatab BangladeshThol, Nou CambodiaSarun, Sam CambodiaLang, Mondul CambodiaSarith, Hin CambodiaPoch, Kep CambodiaRavi, Venkatachalam IndiaVijayalakshmi, B. IndiaIbrahim, M. Nur IndonesiaMindarti, Susi IndonesiaCorpuz, Artemio A. PhilippinesChaikot, Kaensri ThailandLacornket, Chainarong ThailandSatienras, Worwit ThailandHuan, Tran Thi Ngoc VietnamSau, Tran Van Vietnam

Advanced Experimental Design31 May–4 JunMollah, Md. Islam Uddin BangladeshHun, Yadana CambodiaJatmiko, Sigit Yuli IndonesiaTirtoutomo, Susanto IndonesiaPhan, Van Tuan VietnamQuynh, Luu Van VietnamTran, Duc Thach Vietnam

Instructional Video Production7 Jun–2 JulQuraishi, Nazrul BangladeshNorbu, Tandin BhutanQin, Zelin ChinaPrayogo, Kuscahyo Budi IndonesiaVarquez, Frenciso L. PhilippinesLe, Don Dai Vietnam

Introduction to New Developments in G × E Analysisand Interpretation of Results7–11 JunSarom, Men CambodiaSingh, Ashok Kumar IndiaRoy, Ashutosh IndiaSarwoto IndonesiaSengpaseuth, Rasabandith Lao-PDRBhandari, Hem Singh NepalBordeesorn, Juntra ThailandSuriya-Arunroj, Duangjai ThailandChatwachirawong, Prasert ThailandYoungsuk, Piboonwat ThailandQuynh, Luu Van VietnamTran, Duc Thach VietnamPhan, Van Tuan Vietnam

Soil and Water Biochemistry and Ecotoxicology23 Aug–10 SepMin, Liao ChinaKalaichelvan, Gurumurthy IndiaCollado, Wilfredo B. PhilippinesMalabayabas, Myrna D. PhilippinesRuensuk, Nittaya ThailandKunnoot, Laddawan ThailandTrang, Le Thi Dieu Vietnam

Rice Seed Health for Crop Management30 Aug–8 OctHarun, M. Eusuf BangladeshJahan, Quazi Shireen Akhter BangladeshIslam, Md. Shahidul BangladeshHossain, Mohammod BangladeshHossain, Md. Mosaddeque BangladeshKhiev, Bunnarith CambodiaWei, Zhang ChinaSuprihanto IndonesiaSengsoulivong, Viengkham Lao-PDRThavong, Porntip ThailandThuan, Tran Thi Vietnam

Transgenic Rice: Production and Deployment withSpecial Reference to Sheath Blight andRice Stem Borer Resistance11–29 OctAlam, Mohammad Firoz BangladeshIslam, Rafiqul BangladeshGongyin, Ye ChinaSobhakumari, Valiya P. IndiaTummala, Rama Kumar IndiaAyyagari, Phani Padma K. IndiaSellapan, Krishnan IndiaDaradjat, Aan Andang IndonesiaMachmud, Muhammad IndonesiaKim, Hyun-Soon KoreaAbad, Joseph D. PhilippinesAngeles, Amelita T. PhilippinesSoontrajarn, Kasem Thailand

Applications of Molecular Tools to Study Rice Viruses2 Nov–3 DecRai, Ramesh C. IndiaNath, Palash Deb IndiaShrestha, Chandra Laxmi NepalQuan, Hoang Anh Vietnam

Table 4. Participants in short-term group training at IRRI, 1999.


Collaborative in-country training

Collaborative in-country training is a 10-y-old ini-tiative to help develop NARS institutions’ trainingcapability and to complement IRRI training activi-ties at headquarters through partnerships for groupcourses away from IRRI. Fourteen courses wereconducted collaboratively with NARS partner insti-tutions. Those had 361 participants—211 rice sci-entists and 150 farmers—in 12 countries.

REGIONAL COURSES

Regional in-country courses are conducted collabo-ratively with a NARS institution for an internationalgroup of trainees. Two courses were conducted in1999. One was the eighth offering of the course onRice Production Research in collaboration with thePathumthani Rice Research Center of Thailand. Itattracted 18 rice professionals from six countries.The other course was the second offering of thecourse on Adaptive Research in Farming SystemsDevelopment done in collaboration with the Farm-ing Systems Research Institute of the University ofthe Philippines Los Banos (UPLB) for eight partici-pants from four countries.

NATIONAL COURSES

National in-country courses are IRRI courses re-vised to address the specific needs of requestingNARS. Twelve in-country courses were conductedby IRRI for 185 rice professionals in nine countries.Among the courses was the sixth offering of thecourse on Problem-based Technology Generationfor Rice Environments conducted in Cambodia.Twenty rice scientists and agriculture educators par-ticipated in the course.

Program outlook

During 2000, IM will develop its role as a deliveryfacilitation program and its role in linking researchand development. Although IRRI has a long historyof linkage with development organizations, thatlinkage is not widely recognized. Various groupswithin IM will review their roles, functions, prod-ucts, clients, and targets to improve the visibility oftheir activities.

The IM program will increase integration of itsactivities with research. The number of projects willbe reduced to bring similar activities closer to-gether. It is anticipated that many of the TrainingCenter, CREMNET, and the International ProgramsManagement Office activities will merge. Simi-larly, CPS, Library, and Computer Services activi-ties expect greater integration. The aim will then beto imbed IM activities in the research activities. TheIrrigated Rice Research Consortium will be an ini-tial focal point for the merging.

International ProgramsManagement Office (IPMO)The year 2000 will be a period of review and con-solidation of IPMO’s existing mandate and respon-sibilities. The goal is to have better integration ofcountry activities with other research and trainingactivities and to better tap the country repre-sentatives as sources of research needs, priorities,and opportunities. A review of existing protocolswill continue the standardization of operating pro-cedures. The review will include assessment of ourpresence in different countries and the roles neededwith collaborating NARS. We will develop invest-ment criteria and databases that refine IRRI strate-gies for involvement in the different countries. Amulticountry coverage for smaller countries in im-plementing collaboration will be considered.

Training CenterThe activities of the Training Center will be high-lighted by a pro-active posture in the design anddelivery of training events and materials. We are inthe process of seeking opportunities to assist in thedevelopment and delivery of field training based onthe research product and in association with theIRRI research program. Examples of this pro-activeapproach are:

● Indonesian AARD/World Bank TraineeProgram. Ten trainees from Indonesia whohave been through the Rice Production andBio-Statistics courses are currently enrolled inthe Farming Systems course, and willcomplete their 3+-mo on-the-job training withan IPM course. Under past procedure, theywould develop a survey instrument andimplement the practice study at IRRI. For2000, they will return to Indonesia to


implement the farming systems study,including IPM. This will provide the field testof the document and the method and, at thesame time, serve as a baseline study for theIndonesian scientists.

● An example of our proactive approach withour research program is with the Hybrid RiceWorking Group. We are in the process ofdesigning a model workshop with thePhilippine Rice Research Institute that will useIRRI research output in seed breeding andseed production. A multiorganizational teamwill create the materials and workshop design.The workshop will then be replicated in theparticipating countries, with the materialsadapted to local conditions, facilitated byNARS partners, and backstopped by IRRIspecialists.

CREMNETPlans for 2000 include the tighter integration ofCREMNET’s applied research activities with otherIRRI and NARS research partners. Activities willbe defined in light of their fit with other nutrientmanagement research activities. For example,CREMNET will continue to refine the chlorophyllmeter technique with variable rate N applicationbased on a range of SPAD threshold values ob-served at critical crop growth stages. Village-levelevaluation and promotion of the LCC, impact evalu-ation of the LCC method in Vietnam, and the evalu-ation of controlled-release fertilizers for hybrid rice,rice-rice and rice-wheat systems will continue inthree countries.

Development and adaptation of technologies forintegrated crop management for direct-seeded riceand the refinement and promotion of drum seederswill continue in four countries. CREMNET will de-

velop and evaluate TRC, a location-specific pack-age of improved technologies for sustaining highrice productivity in the irrigated ecosystem, in onecountry.

Access to IRRI’s media assetsWe will follow up the 1999 creation of a searchabledatabase for video by adding IRRI’s still photo-graphy collection (an estimated 40,000 images asprint and transparency). Key rice-related imageswill be selected, indexed, and digitized. The videoand still image databases will then be merged to al-low IRRI staff members and clients to access themfor their communication needs in rice research andtraining.

Computer ServicesComputer Services will move across campus to theCPS building for better integration of activities andincreased efficiency of operation. Other improve-ments in efficiency include the planned imple-mentation of several changes to the IRRI network.Staff housing will be brought onto the network, be-ginning with the guesthouse and then with thehomes of scientists. IRRI’s IVDN connection willalso be upgraded to provide a redundant connectionto Manila. Operating system software will be up-graded to Windows 2000 on servers and on selectedPCs.

Computer Services will collaborate actively withCPS in helping the organization shift away frompaper-based information flows. The improvementof IRRI’s Intranet and a move toward electronicrather than printed forms will be key steps in this.The benefits of increasing digitalization and im-proved communications will flow also to IRRI’scountry activities.


Affiliations of collaborating researchers

1Philippine Rice Research Institute, Philippines.2Hokkaido University, Japan.3Assam Agricultural University, India.4Research Institute for Rice, Indonesia.5Central Research Institute for Food Crops, Indonesia.6Indian Agricultural Research Institute, India.7G.B. Pant University of Agriculture and Technology, India.8Natural Resources Institute, UK.9University of Aarhus, Denmark.10Institute of Agricultural Sciences, Vietnam.11Narendra Deva University of Agriculture and Technology, India.12China National Rice Research Institute, China.13Central Rice Research Institute, India.14Punjab Agricultural University, India.15Research Institute for Food Crop Biotechnology, Indonesia.16Yunnan Agricultural University, China.17Zhejiang Academy of Agricultural Sciences, China.18Indian Institute of Soil Science, India.19Chinese Academy of Agricultural Sciences, China.20Bangladesh Rice Research Institute, Bangladesh.21Malaysian Agricultural Research and Development Institute, Malaysia.22Cuu Long Delta Rice Research Institute, Vietnam.23Sichuan Academy of Agricultural Sciences, China.24Indira Gandhi Agricultural University, India.25Mariano Marcos State University, Philippines.26Orissa University of Agricultural Technology, India.27Rajendra Agricultural University, India.28University of Adelaide, Australia.29Zhejiang Agricultural University, China.30Huazhong Agricultural University, China.31Williams College, USA.32Indian Institute of Science, Center for Genetic Engineering, India.33Murugappa Chettiar Research Center, India.34Universitat Bremen, Germany.35University of the Philippines Diliman, Philippines.36Banaras Hindu University, India.37Michigan State University, USA.38Australian National University, Australia.39Sakha Agricultural Research Station, Egypt.40Myanmar Agricultural Service, Myanmar.41M.S. Swaminathan Research Foundation, India.


ANALYTICAL SERVICE LABORATORIES

The Analytical Service Laboratories (ASL) pro-vides analytical and analysis-related services toIRRI research projects. Guidelines for a User Labo-ratory were developed and distributed during 1999.Aside from providing facilities for projects invol-ving the use of radionuclides, the User Laboratoryoffers use of equipment and facilities for organicextraction and chromatography.

Analytical servicesASL completed 61,191 routine analyses for soil,plant, fertilizer, and water samples; elementalanalysis for total C/N, stable isotope ratio analysisfor 13C and 15N, and N and carbohydrates by near-infrared reflectance (NIR) (Table 1).

Improvement of protocolsA library of NIR spectral information for rice plantsamples was developed from an assortment of sam-ples (different plant parts collected at variousgrowth stages) sent for different analyses for the

Research support services

past 3 years. This necessitated the development ofspecific calibrations for the diverse types of samplesand resulted in a large collection of NIR spectra ofsamples with reference chemical analyses. Thespectral library was organized by analyses, plantpart, sample presentation (cup insert used), and bygrowth stage. Spectra of new samples can now bereadily matched to the samples in the library andappropriate samples selected for developing thecalibration.

NIR analysis was initially routine after ASL de-veloped global calibrations applicable to plant sam-ples commonly submitted for N analysis. However,certain analyses required specific calibrations, e.g.,analysis of sugar and starch in rice seedlings. Also,the small amounts (<100 mg) of samples availablefor NIR scanning demanded careful packing andcleaning of the sample cups. A protocol was devel-oped to allow researchers to perform their own NIRanalysis. With ASL training and supervision, a sci-entist researcher can do NIR scanning, select suit-able samples from the library, and perform the cali-bration and prediction.

Table 1. Analyses completed by ASL for IRRI research programs, 1999.

Research programsa served (no. of analyses)Analysis

I R U F C IM Others

Plant analysis 12,427 10,733 2,084 1,270 286 3,592 2,895Soil analysis 4,081 2,185 651 68 – 91 2,236Water analysis 377 619 676 – 278 350 2,301Fertilizer – 12 – – – – 55Mass spectrometry 2,952 30 4,741 132 3,154 – 747Radioisotope counting 1,056 – 1,057 – – – 55

Total 20,893 13,579 9,209 1,470 3,718 4,033 8,289

aI = irrigated, R = rainfed, U = upland, F = flood-prone, C = cross-ecosystems, IM = accelerating impact.

Research support services 139

WINISI v1.02a software was acquired to up-grade NIR data management software from theDOS to Windows version. A new and useful featureis the local calibration, which automaticallymatches each individual sample to the library, se-lects similar samples, and performs calibration foreach sample. This was found to be as much as 25%more accurate than global calibration wherein equa-tions are developed from all samples in the productlibrary.

Data managementASL was successful in implementing electronictransactions (submission of sample identificationforms, receipt notification, analysis query or re-quest) over the IRRI Intranet. ASL clients have ac-cess to the ASL database anytime, anywhere in theworld. Moreover, requests for various services canbe submitted anytime. The only form without an on-line equivalent is the Charge Slip Form.

A software program was developed to imple-ment a secure, reliable, and fast system to validatebudget code and user ID number in electronicforms. The program still needs permission to accesshuman resources development and accounting cen-tral databases and has to go through beta testing be-fore it can be implemented.

User LaboratoryGuidelines for the use of special analytical instru-ments and facilities by non-ASL staff were devel-oped. The User Laboratory includes facilities forchromatography (high-performance liquid chroma-tography, gas chromatography (GC), GC-massspectrometry), radioisotope work (LSC, radio-isotope management), and organic extraction.These facilities serve a multidisciplinary demandand require particular expertise for operation andmaintenance. ASL staff members are available tohelp develop and optimize instrument parametersfor specific applications in collaborative arrange-ments.

Soil organic matter characterization bythermochemolysis with tetramethylam-monium hydroxide (TMAH)ASL continued to provide run-ready facilities forsoil organic matter characterization by thermo-chemolysis as part of the User Laboratory.

Thermochemolysis involves the breakdown of or-ganic macromolecules such as humic acids intosmaller fragments by reaction with 25% TMAH inmethanol at elevated temperature (250 °C).

In a trial run, four humic acid samples from arice-upland crop rotation experiment were analyzedto identify chemical changes associated with timingof crop residue incorporation or crop rotation. Pre-liminary results suggest that aerobic decompositionof crop residues might provide small amounts ofseveral phenolic compounds, implying a more de-composed and possibly less cross-linked nature.This finding agreed with independent conclusionsdrawn from crop nutrient uptake and soil N miner-alization data of the same experiment, indicatingthat early residue incorporation leads to formationof more easily mineralizable organic matter. Thetypes of phenolic compounds detected did not varyby treatment. More reliable conclusions will be pos-sible in 2000 after a complete set of samples fromthis experiment has been analyzed.

Radioisotope LaboratoryThe ASL provided liaison with the Philippine Nu-clear Research Institute on matters related to the useof radioactive materials. The following are newprojects that benefited from those services:

● Use of amplified fragment lengthpolymorphism in the study of variability inrice root-knot nematode populations

● Perenniality and nematode resistance,genomic mapping, and quantitative trait locus(QTL) analysis

● Drought tolerance, root morphology, andallelopathy genetic mapping and QTL analysis

● Transferring osmotic adjustment to japonicaupland rice genotypes through marker-aidedselection

● Allelopathy in upland rice breeding programs● Fine-mapping the major gene underlying P-

deficiency tolerance in rice

BIOMETRICS

The Biometrics Unit’s functions involve researchand service activities. Service activities include pro-viding a consultation facility, quality assurance ad-vice, biometrics training, statistical software, andcomputer services. Research activities include in-


volvement of staff members in the statistical anddata management aspects of research projects and inthe development of statistical techniques and soft-ware required by IRRI research programs.

Service functionsBiometrics provided consultation services to re-searchers, scholars, and fellows ranging from plan-ning and layout of experiments, data collection andanalysis, to interpretation and presentation of re-sults. Ad hoc consultations involved problems inSAS, IRRISTAT, and other software, database de-sign, and questions on statistical concepts. Someconsultations during 1999 were for

● dynamics of rice tungro bacilliform virus(RTBV) accumulation on a susceptible andtolerant host infected with RTBV alone or co-infected with rice tungro spherical virus(RTSV),

● dispersal of yellow stem borers in the field,● estimation of heritability of root-pulling

resistance in rainfed lowland rice,● assessment of milled rice quality in the Philip-

pines,● survey of RTBV/RTSV occurrences in dif-

ferent sites in the Philippines, and● assessment of resistance to brown plant-

hoppers and whitebacked planthoppers ofseveral A, B, and R lines.

TrainingBiometrics participates in Training Center coursesthat contain a statistical component and providestraining workshops and courses for IRRI research-

ers, scholars, and trainees on special topics (Table2).

Software developmentInternational Crop Information System (ICIS) de-velopment continued with refinement of a breeder’sinterface and development of the Data ManagementSystem (DMS). An Excel program called Work-book was developed to access the DMS. It was usedto load INGER data and breeder’s data to a localDMS.

The local DMS for PBGB data for the irrigatedrice ecosystem now contains the evaluation datafrom 1997 DS to 1999 WS for the replicated yieldtrial, observational yield trial, and hybridizationblock trial. IRIS is used for all data management.

The DMS structure is being revised to accommo-date multiple labeling of factors. Simultaneous withthe Workbook revision is the modification of thecentral DMS, the local DMS for the irrigated eco-system, the DMS for the Hybrid Rice project, andthe DMS for INGER.

COMMUNICATION SUPPORT

The Communication and Publications Services unitof the Information Center provides communicationsupport for the entire institute. The services includeediting, graphic design, art and illustration, audio-visual, photography, video, and printing.

The unit printed 1,935,244 pages of text, not in-cluding IRRI books, which were contracted out.About 19,965 original slides were produced; 3,728slides duplicated; and 3,469 black-and-white photo-

Table 2. Training by the Biometrics Unit at IRRI, 1999.

Training Duration Students Comments(no.)

Experimental design and data analysis (EDDA1) 1–12 Feb 15 Includes demonstration of distanceeducation

Introduction to IRRISTAT for Windows 1–5 Mar 14Introduction to SAS for Windows 8–12 Mar 9Introduction to SAS for Windows 26–30 Apr 9Advanced experimental design 31 May–4 Jun 9 Participants from different IRRI outreach

offices.Hybrid rice breeding training course 1 Mar–23 Apr Resource persons for experimental design

and G×EIntroduction to new developments in G×E 7–11 Jun 21 Participants from different RLRRC countries

analysis and interpretation plus Cambodia, Laos, and VietnamRice seed health Aug 30 – 8 Oct Resource person for experimental design,

in-class sampling experiment,and IRRISTAT


graphs printed. IRRI graphic artists produced 204 il-lustrations, laid out 1,335 pages for publication, andprepared 116 posters.

Other activities of the Information Center (pub-lic awareness, scientific publication, library anddocumentation service, and conference and work-shops) are reported in the Accelerating the Impactof Rice Research Program. In addition to the workreported there, IRRI editors worked on 129 journalarticles and miscellaneous papers (conference pa-pers, proposals, and others) totaling about 2,745pages of text, tables, and figures.

COMPUTER SERVICES

Computer Services began work to ensure year 2000(Y2K) compliance in 1998. Computer hardware,software, and other equipment were examined forcompliance. IRRI intranet facilities were used todisseminate information and software. Remedialactions during 1999 included

● shutting down old information systems andmoving applications and data to new systemsand media;

● amending and recompiling IRRI softwareapplications;

● replacing or updating commercial softwareapplications (IRRI accounting system);

● patching operating systems software(Windows 95, NT);

● adding software corrections for noncomplianthardware or disposal or replacement ofnoncompliant hardware; and

● updating affected noncomputer systems(telephone).

CommunicationsExpenditures in all areas of communications cameunder scrutiny in 1999 and a number of areas wereidentified as offering significant potential for sav-ings, most notably in fax costs. Close attention tobilling and cost control detected fraudulent use of aSITA line by email. The password required for ac-cess was changed, and negotiations for a rebate ofthe charges are ongoing.

New email and communications software wasdispatched to outposted staff members, along withup-to-date antivirus software.

IRRI electronic mailA change from an old VAX-based email system toMicrosoft Exchange and an upgrade to a server ca-pable of supporting more than 1,000 mailboxeswere completed. One mail server is reserved for useas a standby system in future.

Dial-in facilities for the campus network wereimproved with the installation of additional phonelines and the replacement of old modems.

Integrated voice and data network (IVDN)The IVDN was upgraded from a 64-k leased line toa 128/256-k frame relay circuit with TMI via HongKong. The old circuit was grossly overloaded withemail queues routinely backing up half a day andlonger.

A contractual standoff with Globe Telecom-munications continued unresolved. A proposal toreplace Globe is expected in the first quarter of2000.

IRRI and the University of the Philippines LosBanos (UPLB) agreed to interconnect their campusnetworks. Shared aims were to improve communi-cations between them (currently routed via theUnited States), improve joint access to commu-nication facilities off campus, and interconnect sat-ellite locations—IRRI staff housing and the OpenUniversity. Connection is expected in 2000 afterUPLB upgrades its campus network.

IRRI staff members have used historically theIVDN as a convenience. In 1999, staff memberswere given detailed information on the costs of us-ing the IVDN vs international direct dialing andmany began to use the cheaper alternative. At 1999prices, IRRI can save a further $25,000–$30,000 perannum on telephone calls.

Monitoring of the use of the IRRI Internet linkwas introduced and tested and found useful in dis-couraging nonbusiness use.

Asset managementThe Y2K inventory and assessment exercise provedto be a wake-up call for asset management. Prob-lems were identified in existing records and man-agement. Computer Services worked on possiblesolutions and initiated discussions on terms of ref-erence with potential outside providers.


EXPERIMENT STATION

The Experiment Station (ES) served 222 requestsfor land and facilities. Land use was:

Division Dry season Wet season(ha) (ha)

PBGB 42.88 55.93GRC 14.41 4.29APPA 8.69 9.43ES1 4.54 5.92CIAT 4.25 4.25EPPD 3.91 5.11SWS 1.99 1.99AED 1.36 1.36

Total 92.03 88.28

A total of 7.3 ha (4 ha dry bed and 3.3 ha wetbed) of nurseries were provided and maintained byES. The dry-bed nurseries were constructed with amodified tractor-powered rototiller with a flutedroller used to mark rows as furrows. The wet-bednurseries were used mainly by PBGB for rice hybridtrials. Sixty-eight tons of different kinds of fertiliz-ers were used in 1999.

ES planted and harvested breeder seed increaseand seed production materials on 20.46 ha of low-land. Kabesilya transplanters were used for seed in-crease plots and a mechanical transplanter, seedblower-spreader, and direct seeding were used forseed production plots. A Thai combine harvesterwas used for all seed harvesting. Integrated pestmanagement (IPM) eliminated the need for insecti-cide applications in all seed increase and productionplots.

A total of 143 t of different rice materials wereprocessed from harvests of seed increase, seed pro-duction, and border rows.

Underground irrigation systems using polyvinylchloride (PVC) pipes were installed in Blocks UE1-4, UU1, and UU4. Five hundred irrigation anddrainage manhole covers were fabricated and in-stalled. Drainage outlets were developed and con-structed in plots C27-37, D10-D14, D15-D23, E6-E27, F1-F10, G2-G21, J2-J13, K2-K10, L2-L8,Lower MN1-7, and Upper MN1-8. Drainage reha-bilitation continued at Blocks 518-531, 602-617,UE, UK, UU, and UV.

Land development work consisted of reorienta-tion of Block UE (4 ha) and conversion of upland tolowland use in Blocks UU1 and UU4 (2 ha) as anadditional area for post-entry quarantine. The upperhalf of Blocks UF4-5 was developed as alternatewet-bed area.

Major road rehabilitation and repair covered 4.5km at Blocks E, F-KL, 706-733, series 900, UC-UF,UE, UJ-UK, US, UT, UY2, and the road betweenthe upland farm and the Institute of Plant Breeding,UPLB.

Pesticide use increased by 31% in 1999, mainlydue to increased molluscicide use on experimentalfields and herbicide use in perimeter fences, fallowareas, and levees. Application of sublethal doses ofnonselective herbicides reduced the cost of mowingin maintaining fallow areas, levees, and perimeterfences.

ES provided rat control services consisting of1,866 baiting stations with 1,800 kg of rat baits forfield and outreach areas. Likewise, 0.92 ha of birdnet and 115 ha of rat fences with 2,259 live trapswere installed.

Expenditures on contract work are 21% higher in1999 than for 1998. Birdboy hours were 10.5%higher than last year but expenditures grew by 82%mainly from an increase in pay rate.

One hundred sixty-five requests for repair andmaintenance of light and heavy equipment and res-ervoir pumps were serviced. Pumps at Blocks JK,MN, UT, and UW reservoirs were converted fromturbine to submersible units. A multipurpose boomsprayer mounted on a ride-on mechanical trans-planter with dual nozzles was tested for field use.

CONTROLLED GROWTH FACILITIES AND GROUNDS

Controlled Growth Facilities and Grounds (CGFG)supported 48 experiments at the phytotron, 143 ex-periments in greenhouses, and more than 16 experi-ments in the confinement level 4 (CL4) transgenicgreenhouses. A total of 1,174 maintenance servicerequests were served. Those included provision of728 t of ground soil to experiments in the green-houses and the fields.


Controlled growth facilitiesWork in controlled growth facilities during 1999covered:

● New, reliable, user-friendly software andhardware were installed for the upgrade of thephytotron automatic climate control system.

● Renovation of the cooling system and thecanopies of the 12 outdoor growth cabinets(OGC) was completed.

● Rewiring and reconditioning of the indoorgrowth cabinets pumping system and the sumppit tank was completed.

● Twelve stainless humidifier tanks werefabricated specifically for the OGCs to replaceold units, facilitate shutdown operations, andreduce OGC humidifier servicing time.

● Repair and replacement of 16 solar panels wasdone as part of a gradual upgrade of the 64units of solar panels of the phytotron heatingsystem.

● The quarantine screenhouse and associatedwork areas plus the cooling tower that servicesthe indoor growth cabinets were refurbished.

● Brackets of the condenser fan motors of theCL4 greenhouse cooling system weremodified to protect the motors from theelements and simplify machine maintenanceand operation procedures.

The greenhouse unit maintained 44 glasshouseand screenhouse structures and provided a widerange of services to facilitate conduct of experi-ments. Increased demand for soil and expandednumber of experiments in the greenhouses madesoil grinding the main workload. Acquisition of anadditional soil grinder with associated coveredspace, plus an appropriate soil hauling mini-dumptruck, was recommended to improve productivityand efficiency of the unit.

Industrial grade exhaust fans were installed in 16glasshouses in cluster B and cluster N to improve aircirculation and help reduce inside summer tempe-ratures. The lighting and environment control sys-tems of the cluster N darkrooms were renovated.Extended roofing and concrete flooring were in-

stalled in one processing area in cluster B. Concretewalls were installed in one cluster A screenhouse toreplace rusted metal walls.

Refurbishment of the structures and replacementof the screening of the screenhouse in the uplandarea was completed.

An annual, staggered, 1-mo shutdown periodwas fully implemented as a standard procedure forall greenhouses, CL4, and the phytotron plant-growing areas. This allowed general cleanup andwashdown of all structures and provided for pro-phylactic treatment against pests, as well as preven-tive maintenance of cooling systems and structures.The shutdown disrupted insect and disease cyclesand reduced the frequency of chemical sprayingagainst pests by as much as 40%.

GroundsThe grounds unit provided landscape maintenanceand development services including garbage collec-tion for the research center and 104 residential units.Garbage collection routes and schedules were re-vised to improve efficiency of the service.

A waste segregation program for residences andthe research center resulted in high earnings fromsale of materials. Sales in the 1999 last-quarter scrapauction were about US$1.2 million pesos.

Two indoor gardens in the F.F. Hill Hall werelandscaped to improve aesthetic appeal and reducemaintenance costs.

Improvements in the safety, security, and mobil-ity in the plant propagation work areas were donethrough installation of fences, plant benches, andground surface cover, and through improvements inthe blocking and arrangement of pot plants. Re-moval of some more hedges in applicable areas ofthe research center further streamlined groundsmaintenance operations. Other improvements togrounds and landscaping were construction of a py-lon marker at the entrance of the research center andinstallation of an underground sprinkler system inlawn areas fronting Chandler Hall and F.F. HillHall.

Publications and seminars 145

Publications and seminars

Institute publications

BooksGenetic improvement of rice for water–limited

environments. 1999. 353 p.Increasing rice production in Bangladesh: chal-

lenges and strategies. 1999. 167 p.INGER-derived rice varieties directly released in

various countries. 1999. 37 p.IRRI 1998-1999: Rice–hunger or hope. 1999. 57 p.Program report for 1998. 1999. 187 p.Resource management in rice systems: nutrients.

1999. 355 p.Upland rice weeds of South and Southeast Asia.

1999. 156 p.

Periodicals/serialsInternational rice research notes, vol. 24, nos. 1-3.IRRI discussion paper series, No. 37.IRRI limited proceedings series, No. 1.IRRI technical bulletin series, Nos. 1-6.

Agricultural Engineering

Bell MA. 1999. A brighter future. Resource:13-14.Bell MA, Cedillo P. 1999. Mechanization in Asia:

statistics and principles for success. Agric.Mech. Asia, Africa, Latin Am. 30(4):70-75.

Agronomy, Plant Physiology,and Agroecology

Azmi M, Mortimer AM. 1999. Effect of tillagepractices, seeding rates and herbicides onbarnyardgrass infestation (Echinochloa crus-galli) in direct seeded rice. In: Proceedings ofthe 17th Asian-Pacific Weed Science SocietyConference, Bangkok, Thailand. p 199-204.

Bach Jensen L, Courtois B, Olofsdotter MO, ShenL, Mauleon RP, Li Z. 1999. See Plant Breed-ing, Genetics, and Biochemistry.

Banziger M, Edmeades GO, Lafitte HR. 1999. Se-lection for drought tolerance increases maizeyields across a range of nitrogen levels. CropSci. 39:1035-1040.

Bird JA, Horwath WR, van Kessel C, Hill JE. 1999.Effect of flooding and straw residue manage-ment on soil bulk density in two floodedVertisols: implications for nutrient cycling re-search. ASA-CSSA-SSSA Annual MeetingAbstracts, Salt Lake City, Utah, 31 Oct-4 Nov.p 237.

Breen JL, Hill JE, Kusanagi T. 1999. Tiller densitydetermines competitive outcome between wa-ter-seeded rice (Oryza sativa L.) andMonochoria vaginalis var. vaginalis. J. WeedSci. Technol. 44(3):180-188.

Castella J-C, Gayte O, Do Minh Phuong. 1999. Be-tween micro- and macrolevel studies, the questfor a meso-level for effective community-basednatural resource management in Vietnam up-lands. In: Kam SP, Hoanh CT, editors. Scalingmethodologies in ecoregional approaches fornatural resource management. Limited pro-ceedings of an international workshop, 22-24Jun 1998, Ho Chi Minh City, Vietnam. MakatiCity, Philippines: Intenational Rice ResearchInstitute. p 93-107.

Castella J-C, Husson O, Le Quoc Doanh, Ha DinhTuan. 1999. Implementing the ecoregional ap-proach in the Red River Basin uplands, Viet-nam. In: Kinh NN et al, editors. Towards anecoregional approach for natural resource man-agement in the Red River Basin of Vietnam.Hanoi, Vietnam: The Agricultural PublishingHouse. p 75-94.


Castella J-C, Husson O, Le Quoc Doanh, Ha DinhTuan. 1999. Mise en oeuvre de l’approcheécorégionale dans les montagnes du bassin duFleuve Rouge au Vietnam [in French]. Cah.Rech.-Dév. 45:114-134.

Castella J-C, Jourdain D, Trébuil G, Napompeth B.1999. A systems approach to understandingobstacles to effective implementation of IPM inThailand: key issues for the cotton industry.Agric. Ecosyst. Environ. 72:17-34.

Castella J-C, Kam SP, Hoanh CT. 1999. The RedRiver Basin (Vietnam) pilot region for opera-tional ecoregional approach: new mechanismsfor reconciling macro and micro studies, bio-physical and socioeconomic perspectives innatural resource management. Contribution toSAAD-3. The Third International Symposiumon Systems Approaches for Agricultural De-velopment: Methodologies for Interdiscipli-nary, Multi-scale Perspectives, 8-10 Nov 1999,Lima, Peru. 15 p.

Caton BP, Foin TC, Hill JE. 1999. A plant growthmodel for integrated weed management in di-rect-seeded rice. I. Development and sensitiv-ity analyses of monoculture growth. FieldCrops Res. 62:129-143.

Caton BP, Foin TC, Hill, JE. 1999. Plant growthmodel for integrated weed management in di-rect-seeded rice. II. Validation testing of water-depth effects on monoculture growth. FieldCrops Res. 62:145-155.

Caton BP, Foin TC, Hill JE. 1999. A plant growthmodel for integrated weed management in di-rect-seeded rice. III. Interspecific competitionfor light. Field Crops Res. 63(1):47-61.

Caton BP, Mortimer AM, Foin TC, Hill JE, GibsonKD, Fischer AJ. 1999. Weed morphology ef-fects on competitiveness for light in direct-seeded rice. In: Proceedings of the 17th Asian-Pacific Weed Science Society Conference,Bangkok, Thailand. p 116-120.

Chauhan RPS, Singh BB, Singh VP. 1999. Strate-gic nutrient management for sustained rice pro-duction in sodic soils. Fert. Newsl. 44(8):13-26.

Chopart LJ, Siband P. 1999. Development and vali-dation of a model to describe root length den-sity of maize from root counts on soil profiles.Plant Soil 214:61-74.

Cohen MB, Jackson MT, Lu BR, Morin SR,Mortimer AM, Wade LJ. 1999. Predicting theenvironmental impact of transgene outcrossingto wild and weedy rices in Asia. In: LutmanPJW, editor. Gene flow and agriculture: rel-evance for transgenic crops. British Crop Pro-tection Council Symposium. p 151-157.

Cooper M, Fukai S, Wade LJ. 1999. How canbreeding contribute to more productive andsustainable rainfed lowland rice systems? FieldCrops Res. 64:199-209.

Dizon MA, Migo TR, Mortimer AM. 1999. Under-standing weed competition in direct seededrice: an examination of Echinochloa crus-galliat the plant level. Philipp. J. Crop Sci. 2:81.

Eagle AJ, van Kessel C, Horwath WR, Bird JA, HillJE. 1999. Nitrogen cycling dynamics under al-ternative rice straw management practices.ASA-CSSA-SSSA Annual Meeting Abstracts,Salt Lake City, Utah, 31 Oct-4 Nov. p 220.

Edmeades GO, Bolanos J, Chapman SC, LafitteHR, Banziger M. 1999. Selection improvesdrought tolerance in tropical maizepopulations. I. Gains in biomass, grain yield,and harvest index. Crop Sci. 39:1306-1315.

Fukai S, Cooper M, Wade LJ. 1999. Adaptation ofrainfed lowland rice. Field Crops Res. 64:1-2.(Preface)

Fukai S, Cooper M, Wade LJ. 1999. Adaptation ofrainfed lowland rice. Field Crops Res. 64:1-210. (Special issue)

Garcia CO, Piggin CM, Janiya JD, Bell MA, Castro E,Razote E, Hill JE. 1999. Establishment of irri-gated lowland rice under zero and conventionaltillage systems in the Philippines. In: Proceed-ings of the 17th Asian-Pacific Weed ScienceSociety Conference, Bangkok, Thailand. p226-231.

George T, Quiton J, Manoharan V, Corton T, Yost R.1999. Adaptation of the nutrient managementsupport system (NuMaSS) in Asia. In: Pro-ceedings of the International Symposium onSystems Research for Optimizing Future LandUse. International Rice Research Institute, 11-13 Oct 1999, Los Baños, Laguna, Philippines.

Huang S, Yu L, Watson AK. 1999. Study of conidiaproduction characterization of barnyardgrassfungi Alternaria alternata and Curvularia lu-nata. In: Proceedings of the 6th Weed Science


Conference of China, 19-21 Mar 1999,Nanning, China. p 165-169.

Inderjit, Olofsdotter M. 1999. Allelopathy inagroecosystem. In: Proceedings of the 11th

EWRS (European Weed Research Society)Symposium, Basel. p 63.

Janiya JD, Dizon MA, Mortimer AM, Piggin C, HillJE. 1999. The impact of cropping practices onrice-weed communities. In: Proceedings of the17th Asian-Pacific Weed Science Society Con-ference, Bangkok, Thailand. p 146-151.

Kam SP, Castella J-C, Hoanh CT. 1999. Methodol-ogy Integration under the Ecor(I)Asia. Contri-bution to the Symposium on Systems Researchfor Optimizing Future Land Use (SysNet’99),11-13 Oct 1999, International Rice ResearchInstitute, Los Baños, Philippines. 5 p.

Kamoshita A, Wade LJ, Siopongco J, Sarkarung S,Nguyen HT. 1999. Phenotyping and tagginggenes for constitutive root traits. Philipp. J.Crop Sci. 24:8.

Kamoshita A, Wade LJ, Yamauchi A. 1999. Pros-pect for crop-soil research for rainfed lowlandrice improvement. In: Horie T, Geng S, AmanoT, Inamura T, Shiraiwa T, editors. World foodsecurity and crop production technologies fortomorrow. Kyoto: Crop Science Society of Ja-pan. p 217-220.

Kim JK, Peng S, Park ST. 1999. Direct seedingtechnology for irrigated rice in Asia. J. KoreanSoc. Int. Agric. 11(3):225-233.

Kinh NN, Teng PS, Hoanh CT, Castella JC. 1999.Towards an ecoregional approach for naturalresource management in the Red River Basinof Vietnam. Hanoi, Vietnam: The AgriculturalPublishing House. 254 p.

Kumar D, Chauhan RPS, Singh BB, Singh VP.1999. Response of rice to zinc sulfate incubatedand blended with organic materials. Indian J.Agric. Sci. 66(6):402-405.

Kyu H, Amarante ST, Gomez A, Samonte HP,Robles RP, Wade LJ. 1999. Variation in seedand seedling vigor in wet-seeded rice. Philipp.J. Crop Sci. 24:42.

Latore J, Gould P, Mortimer AM. 1999. Effects ofhabitat heterogeneity and dispersal strategieson population persistence in annual plants.Ecol. Model. 58:382-389.

Lhoste P, Tonneau JP, Trebuil G. 1999. Rechercheécorégionale et développement régional:enjeux, démarche et outils [in French]. Cah.Rech.-Dév. 45:7-36.

Mabbayad MO, Watson AK. 1999. Rejection ofFusarium pallidoroseum as a biological controlagent of Mimosa invisa in upland rice. In: Pro-gram Abstracts, Tenth International Sympo-sium on Biological Weed Control, 4-14 Jul1999, Bozeman, Montana. p 121.

Manichon H, Trebuil G. 1999. An ecoregional ap-proach for development-oriented research onagricultural systems. In: Kinh NN, Teng PS,Hoanh CT, Castella JC, editors. Towards anecoregional approach for natural resource man-agement in the Red River Basin of Vietnam.Hanoi, Vietnam: The Agricultural PublishingHouse. p 13-28.

Masangkay RF, Mabbayad MO, Paulitz TC,Watson AK. 1999. Host range of Alternariaalternata f. sp. sphenocleae causing leaf blightof Sphenoclea zeylanica. Can. J. Bot. 77:103-112.

Masangkay RF, Paulitz TC, Hallett SG, WatsonAK. 1999. Factors influencing biological con-trol of Sphenoclea zeylanica with Alternariaalternata f. sp. sphenocleae. Plant Dis.83:1019-1024.

Mortimer AM, Caton BP, Hill JE. 1999. On eco-logical issues in the development of sustainableweed management. In: Proceedings of the 17th

Asian-Pacific Weed Science Society Confer-ence, Bangkok, Thailand. p 45-50.

Mortimer AM, Hill JE. 1999. Weed species shiftsin response to broad-spectrum herbicides insub-tropical and tropical crops. BCPC 2:425-437.

Murchie EH, Chen Y, Hubbart S, Peng S, Horton P.1999. Interactions between senescence and leaforientation determine in situ patterns of photo-synthesis and photoinhibition in field-grownrice. Plant Physiol. 119:553-563.

Olofsdotter M. 1999. Allelopathy–a future compo-nent in weed management. In: Proceedings ofthe 16th Danish Crop Protection Conference onWeeds. p 101-112.

Olofsdotter M. 1999. Lessons to be learned fromrice allelopathy. In: Proceedings of the SecondWorld Congress on Allelopathy–Critical


Analysis and Future Prospects, Thunder Bay,Canada, 8-13 Aug 1999. (Abstract). p 141.

Olofsdotter M, Inderjit. 1999. Allelopathy. In:Jensen JE, Andreasen, Sieden P, editors. Weedscience. KVL. p 337-355.

Olofsdotter M, Navarez D, Rebulanan M, StreibigJC. 1999. Weed suppressing rice cultivars–does allelopathy play a role? Weed Res.39(6):441-454.

Peng S, Cassman KG, Virmani SS, Sheehy JE,Khush GS. 1999. Yield potential trends oftropical rice since the release of IR8 and thechallenge of increasing rice yield potential.Crop Sci. 39:1552-1559.

Peng S, Sanico AL, Garcia FV, Laza RC, VisperasRM, Descalsota JP, Cassman KG. 1999. Effectof leaf phosphorus and potassium concentra-tion on chlorophyll meter reading in rice plant.Plant Prod. Sci. 2(4):227-231.

Pheng S, Adkins S, Olofsdotter M, Jahn G. 1999.Allelopathic effects of rice (Oryza sativa) onthe growth of awnless barnyardgrass(Echinochloa colona (L.) Link.): A new formfor weed management. Cambodian J. Agric.2(1):42-49.

Pheng S, Adkins S, Olofsdotter M, Jahn G. 1999.The search for allelopathic rice in Cambodia:allelopathic effects of modern rice varieties,Cambodian traditional rice varieties (Oryzasativa L.) and wild rice (Oryza nivara Sharmaet Shastry and Oryza rufipogon Griff.) on awn-less barnyardgrass [Echinochloa colona (L.)Link]. Proceedings of the 17th Asian-Pacificweed Science Society Conference, Weeds andEnvironmental Impact, Bangkok, 22-27 Nov1999.

Ram PC, Singh AK, Singh BB, Singh VK, SinghHP, Setter TL, Singh VP, Singh RK. 1999.Characterization of floodwater in eastern India:relevance to submergence tolerance of rice.Exp. Agric. 33:141-152.

Rodriguez R, Mazid MA, Harnpichitvitaya D,Wade LJ, Raab R, Balasubramanian V, BellMA, Teng PS. 1999. Transfer of rice-relatedtechnologies in partnership with researchers,farmers, and nongovernment organizations.Philipp. J. Crop Sci. 24:31.

Roetter R, Hoanh CT. 1999. Exploring land use op-tions under multiple goals in support of natural

resource management at subnational level. In:Kinh NN, Teng PS, Hoanh CT, Castella JC,editors. Towards an ecoregional approach fornatural resource management in the Red RiverBasin of Vietnam. Hanoi, Vietnam: The Agri-cultural Publishing House. p 29-57.

Roetter R, Van de Geijn SC. 1999. Climate changeeffects on plant growth, crop yield and live-stock. Clim. Change 43:651-681.

Sheehy JE, Mitchell PL, Tsukaguchi T, DionoraMJA, Ferrer A, Torres R. 1999. Breaking theyield barrier in rice: problems and solutions.Does radiation use efficiency limit rice yield inthe tropics. In: Horie T, Geng S, Amano T,Inamura T, Shiraiwa T, editors. World food se-curity and crop production technologies for to-morrow. Kyoto University, Kitashirakawa,Sakyou-ku, Kyoto, Japan. p 147-151.

Sinclair TR, Sheehy JE. 1999. Erect leaves and pho-tosynthesis in rice. Science 283:1456-1457.

Singh G, Singh OP, Singh RK, Singh VP, Nayak R.1999. Production potential of rice-based crop-ping systems in rainfed lowland situations.Oryza 36(1):57-62.

Singh U, Patil SK, Das RO, Padilla JL, Singh VP,Pal AR. 1999. Nitrogen dynamics and cropgrowth on an alfisol and vertisol under rainfedlowland rice-based systems. Field Crops Res.61:237-252.

Singh VP, Minh VQ, Singh AN, Kam SP. 1999.Ecosysem analysis-based methodology fortechnology extrapolation. In: BalasubramanianV et al, editors. Resource management in ricesystems: nutrients. The Netherlands: KluwerAcademic Publishers. p 213-229.

Singh VP, Singh RK, Sastri ASRAS, Baghel SS,Chaudhry JL. 1999. Agroclimatic atlas of East-ern India. Indira Gandhi Agricultural Univer-sity and Makati (Philippines): InternationalRice Research Institute. 76 p.

Smitaman P, Panyafoo S, Watson AK. 1999.Screening of selective biocontrol agents forLeptochloa chinensis (L.) Nees. in Thailand.In: Proceedings of the 17th Asian-Pacific WeedScience Society Conference, 22-27 Nov, Bang-kok, Thailand. p 567-572.

Srivastava PC, Gangwar MS, Singh VP. 1999. Ad-sorption-desorption of zinc in mollisols andtheir relationship with the uptake of fertilizer


applied zinc by rice. Commun. Soil Plant Anal.30(3-4):471-481.

Srivastava PC, Ghosh D, Singh VP. 1999. Evalua-tion of different zinc sources for lowland riceproduction. Biol. Fertil. Soil 30(1 & 2):168-172.

Tsukaguchi T, Sheehy JE, Ito O, Horie T. 1999.Analysis of grain filling of individual tillers ofrice based on their emergence time and NSVcontent in genotypes of IR72 and new planttype. In: Horie T, Geng S, Amano T, InamuraT, Shiraiwa T, editors. World food security andcrop production technologies for tomorrow.Kyoto University, Kitashirakawa, Sakyou-ku,Kyoto, Japan. p 298-299.

Turkelboom F, Trebuil G. 1999. Approche intégréede l’érosion des sols en milieu paysan : appli-cation aux collines du nord de la Thaïlande. In:Gestion agrobiologique des sols et dessystèmes de culture. Rasolo F, Raunet M, edi-tors. Actes de l’atelier international, Antsirabe,Madagascar, 23-28 mars 1998, Anae, Cirad,Fafiala, Fifamor, Fofifa, Tafa. Montpellier,France, CIRAD, Collection Colloques. p 367-383.

Van Keer K, Trebuil G, Thiraton A. 1999. Le sel:un herbicide populaire sur riz pluvial au nord-Thaïlande. Agric. Dév. 21:99-109.

Wade LJ. 1999. Research balance, impact deliveryand future challenges in crop-soil managementsystems. In: Horie T, Geng S, Amano T,Inamura T, Shiraiwa T, editors. World food se-curity and crop production technologies for to-morrow. Crop Science Society of Japan,Kyoto. p 247-249.

Wade LJ, Amarante ST, Olea A, HarnpichitvitayaD, Naklang K, Wihardjaka A, Sengar SS,Mazid MA, Singh G, McLaren CG. 1999. Nu-trient requirements in rainfed lowland rice.Field Crops Res. 64:91-107.

Wade LJ, Fukai S, Samson BK, Ali A, Mazid MA.1999. Rainfed lowland rice: physical environ-ment and cultivar requirements. Field CropsRes. 64:3-12.

Wade LJ, McLaren CG. 1999. Exploiting varietaland genetic suitability in variable environ-ments—exploiting the E in GXE. In: Geo-in-formation techniques for understanding andanalysing rainfed rice environments in easternIndia. Lucknow, India, 24-26 May 1999.

Wade LJ, McLaren CG, Quintana L,Harnpichitvitaya D, Rajatasereekul S, SarawgiAK, Kumar A, Ahmed HU, Sarwoto, SinghAK, Rodriguez R, Siopongco J, Sarkarung S.1999. Genotype by environment interactionsacross diverse rainfed lowland rice environ-ments. Field Crops Res. 64:35-50.

Watson AK. 1999. Can viable weed control be at-tainable with microorganisms? In: Hong LW,Sastroutomo SS, Caunter IG, Ali J, Yeang LK,Vijaysegaran S, Sen YH, editors. Biologicalcontrol in the tropics. 18-19 Mar 1999,Serdang, Malaysia. CAB International. p 59-63.

Zhang W, Watson AK. 1999. Isolation and partialcharacterization of phytotoxins produced byExserohilum monoceras, a potentialbioherbicide for control of Echinochloa spe-cies. In: Program abstracts. Tenth InternationalSymposium on Biological Weed Control, 4-14Jul 1999, Bozeman, Montana. p 71.

Zhong X, Peng S, Sheehy JE, Liu H, Visperas RM.1999. Parameterization, validation and com-parison of three tillering models for irrigatedrice in the tropics. Plant Prod. Sci. 2(4):258-266.

Yu L, Watson AK, Huang S, Xu Z, Wang Y. 1999.Control of Monochoria vaginalis in rice withthe indigenous pathogenic fungi. China RiceRes. Newsl. 7(2):6-7.

CREMNET

Balasubramanian V. 1999. Farmer adoption of im-proved nitrogen management technologies inrice farming: technical constraints and oppor-tunities for improvement. Nutr. Sci.Agroecosyst. 53:91-101.

Balasubramanian V, Fischer KS. 1999. Rice: globalachievements and advances in innovative tech-nology development and dissemination. In:Proceedings of the 19th Session of the Interna-tional Rice Commission, Cairo, Egypt, 7-9 Sep1998. International Rice Commission on as-sessment and orientation towards the 21st cen-tury. Food and Agriculture Organization,Rome, Italy. p 181-193.

Balasubramanian V, Morales AC, Cruz RT,Abdulrachman S. 1999. On-farm adaptation ofknowledge-intensive nitrogen management


technologies for rice systems. Nutr. Cycl.Agroecosyst. 53:59-69.

Balasubramanian V, Morales AC, Nagarajan R,Ramanathan SP. 1999. Efficiency of resin +wax- and polyolefin-coated urea in tropicalflooded rice. 1999 Annual Meeting Abstracts.ASA-CSSA-SSSA, Salt Lake City, Utah, 31Oct–4 Nov 1999. p 40.

Chuahan RPS, Singh BB, Singh RK, Singh VP.1999. Strategic nutrient management for sus-tained rice production in sodic soil. Fert. News44(8):13-16, 19-23, 25-26.

Cox P, Jahn GC, Mak S, Chhorn N. 1999. Farmerparticipatory research for the design of im-proved rat management systems. Workshop onDeveloping a Research Framework for FarmerParticipation in Rat Management, 19-23 July1999, Ho Chi Minh, Vietnam.

Cox P, Mak S. 1999. Participatory farmer researchfor the management of rats in Cambodia. Cam-bodian J. Agric. 2(1):23-28.

Jahn GC, Mak S, Cox PG, Chhorn N. 1999. Farmerparticipatory research on rat management inCambodia. In: G. Singleton, Hinds L, Leirs H,Zhang Z, editors. Ecologically based rodentmanagement. p 358-371. Canberra (Australia):Australian Centre for International AgriculturalResearch.

Khiev B, Jahn GC, Pol C, Chhorn N. 1999. Simu-lating rice pest damage to determine effects onyield. Cambodian J. Agric. 2(1):29-31.

Kongchum M, Wuti Niponkit, Buresh RJ,Puckridge DW. 1999. Soil nitrate as a source ofnitrogen for rainfed and deep-flooded rice. ThaiAgric. Res. J. 17(2):174-184.

Lantican M, Lampayan RM, Bhuiyan SI, YadavMK. 1999. Determinants of improving produc-tivity of dry-seeded rice in rainfed lowlands.Exp. Agric. (35):127-140.

Mohanty SK, Singh U, Balasubramanian V, Jha KP.1999. Nitrogen deep-placement technologiesfor productivity, profitability, and environmen-tal quality of rainfed lowland rice systems.Nutr. Cycl. Agroecosyst. 53:43-57.

Phaloeun C, Vuthy T, Sakkhunthea S, Nesbitt HJ.1999. New technology and farming systems inCambodia. Cambodian J. Agric. 2(1):38-41.

Pheng S, Adkins S, Olofsdotter M, Jahn G. 1999.Allelopathic effects of rice on awnless

barnyardgrass. Cambodian J. Agric. 2(1):42-48.

Pheng S, Adkins S, Olofsdotter M, Jahn GC. 1999.The search for allelopathic rice in Cambodia.In: Proceedings of the 17th Asian-Pacific WeedScience Society Conference, 22-27 Nov 1999,Bangkok, Thailand.

Ram PC, Singh AK, Singh BB, Singh VK, SinghHP, Setter TL, Singh VP, Singh RK.1999. En-vironmental characterization of flood water ineastern India: relevance to submergence toler-ance of lowland rice. Exp. Agric. 35(2):141-152.

Rickman JF, Som B, Pao S, Meas P. 1999. Ricemilling in Cambodia. Cambodian Agric. J.2(1):49-51.

Singh G, Singh OP, Singh RK, Singh VP, Nayak R.1999. Production potential of rice-based crop-ping systems in rainfed lowland situation ofeastern Uttar Pradesh, India. Oryza 36(1):57-62.

Singh RK, Prasad K. 1999. Farmers' participatoryplant breeding. In: Proceedings of SummerSchool on Advances in Seed Sciences andTechnology, New Delhi, India, 28 Apr-27 May1999. p 263-270.

Singh ON, Singh S, Singh RK, Sarkarung S. 1999.Screening for submergence tolerance usingdouble-haploid rice lines for rainfed lowlands.Oryza 36(1):38-41.

Singh RK. 1999. Genetic resources and the role ofinternational collaboration in rice breeding.Genome 42:635-641.

Singh RK. 1999. Planning for improved productiv-ity and sustained rice production in eastern In-dia. India Grains 1(3):15-16.

Singh VP, Singh RK, Sastri ASRAS, et al. 1999.Rice-growing environments of eastern India:an agro-climatic atlas. IRRI-GAU. 76 p.

Tang SX, Ding L, Wang ZQ. 1999. Exploitingbiodiversity for sustainable pest managementin rice field. World Agric. (237):28.

Tang SX, Jiang YZ, Li SS. 1999. Observation onthe amyloplasts in endosperm of early Indicarice with scanning electron microscpe. ActaAgron. Sin. 25(2):269-272.

Tang SX, Jiang YZ, Zhang BD, Lu YL. 1999.Biodiversity of rice growing regions in China.Chin. Biodiversity 7(1):73-78.


Tang SX, Zhang WX, Liu J. 1999. The study on theBi-Peak-tubercle on lemma of Hemudu andLuojiajiao ancient excavated rice grains withelectric scanning microscope. Acta Agron. Sin.25(3):269-272.

White PF, Seng V, Ros C, Nesbitt HJ, Chan P.1999. Nutrient and organic matter managementin cash-poor, rice-based cropping systems inCambodia: research and extension needs in nu-trient and organic matter management in cash-poor rice-based farming systems. In: SE Asia:research and adoption needs in Laos, Thailand,Cambodia and Vietnam. Proceedings of an in-ternational workshop held in Vientiane, Laos,21-22 Apr 1999. Canberra (Australia): Austral-ian Centre for International Agricultural Re-search.

Wade LJ, Amarante ST, Olea A, HarnpichitvitayaD, Naklang K, Wihardjaka A, Sengar SS,Mazid MA, Singh G, McLaren CG. 1999. Nu-trient requirements in rainfed lowland rice.Field Crops Res. 64:91-107.

Wade LJ, CG McLaren, L Quintana,Harnpichitvitaya D, Rajatasereekul S, SarawgiAK, Kumar A, Ahmed HU, Sarwoto, SinghAK, Rodriguez R, Siopongco J, Sarkarung S.1999. Genotype by environment interactionsacross diverse rainfed lowland rice environ-ments. Field Crops Res. 64:35-50.

Entomology and Plant Pathology

Adhikari TB, Basnyat RC, Mew TW. 1999. Viru-lence of Xanthomonas oryzae pv. oryzae onrice lines containing single resistance genesand gene combinations. Plant Dis. 83:46-50.

Arboleda M, Azzam O. 1999. Inter- and intrasitegenetic diversity of natural field populations ofrice tungro bacilliform virus in the Philippines.Arch. Virol. 144:1-15.

Arboleda M, Sta Cruz F, Azzam O. 1999. Prelimi-nary analysis of genetic variation of rice tungrobacilliform virus in two provinces of the Phil-ippines. In: Chancellor TCB, Azzam O, HeongKL, editors. Proceedings of the Workshop onRice Tungro Disease Management, 9-11 Nov1998, Los Baños, Philippines.

Azzam O, Yambao Ma. LM, Muhsin M, McNallyK, Umadhay K. 1999. Genetic diversity of ricetungro spherical virus in tungro-endemic prov-

inces of the Philippines and Indonesia. Arch.Virol. 145:1183-1197.

Cabauatan PQ, Melcher U, Ishikawa K, Omura T,Hibino H, Koganezawa H, Azzam O. 1999.Sequence changes in six variants of rice tungrobacilliform virus and their phylogenetic rela-tionships. J. Gen. Virol. 80 (8):2229-2237.

Cohen MB, Jackson MT, Lu BR, Morin SR,Mortimer AM, Wade LJ. 1999. Predicting theenvironmental impact of transgene outcrossingto wild and weedy rices in Asia. In: Gene flowand agriculture: relevance for transgenic crops.BCPC Symposium Proceedings no. 72. BritishCrop Protection Council: Brighton. p 151-156.

Datta K, Velazhahan R, Oliva N, Ona I, Mew T,Khush GS, Muthukrishnan S, Datta SK. 1999.See Plant Breeding, Genetics, and Biochem-istry.

Escalada MM, Heong KL, Huan NH, Mai V. 1999.Communications and behavior change in ricefarmers’ pest management: the case of usingmass media in Vietnam. J. Appl. Commun. 83(1):7-26.

Heong KL. 1999. From research to farmer prac-tice—a case study in rice pest management. In:Balasubramanium V, Ladha JK, Denning GL,editors. Resource management in rice systems:nutrients. The Netherlands: Kluwer AcademicPublishers. p 199-212.

Heong KL. 1999. New paradigms and research op-portunities in rice pest management. In: ZhangR, Gu D, Zhang W, Zhou C, Pang Y, editors.Proceedings of the International Symposiumon IPM in Rice-Based Ecosystems,Guangzhou, Peoples’ Republic of China. 20-24Oct 1997. Guangzhou, (China): ZhongshanUniversity. p 3-14.

Heong KL, Escalada MM. 1998. Changing ricefarmers’ pest management practices throughparticipation in a small-scale experiment. Int. J.Pest Manage. 44:191-197.

Heong KL, Escalada MM. 1999. Quantifying ricefarmers’ pest management decisions — beliefsand subjective norms in stem borer control.Crop Prot. (18):315-322.

Huan NH, Mai V, Escalada MM, Heong KL. 1999.Changes in rice farmers’ pest management be-tween 1992 and 1997 in the Mekong Delta, Vi-etnam. Crop Prot. (18):557-563.


Islam Z, Heong KL. 1998. Abundance and preda-tory behavior of wasps of non-rice habitats inrice ecosystems in the Philippines. BangladeshJ. Entomol. 8:31-44.

Islam Z, Heong KL. 1999. Effects of tillage on ar-thropod predators of rice insect pests in irri-gated rice. In: Zhang R, Gu D, Zhang W, ZhouC, Pang Y, editors. Proceedings of the Interna-tional Symposium on IPM in Rice-Based Eco-systems, Guangzhou, Peoples’ Republic ofChina, 20-24 Oct 1997. Guangzhou (China):Zhongshan University. p 198-208.

Mew TW, Merca SD, Tuazon ED. 1999. In: KahnRP, Mathur SB, editors. Containment facilitiesand safeguards for exotic plant pathogens andpests. St. Paul, Minnesota: APS Press. p. 38-43.

Mew TW, Castilla CP, Huelma CC. 1999. Currentstatus and future needs for inoculum thresholdof seedborne pathogens—the basis for plantquarantine regulations. Abstract. p 9. Proceed-ings of the 3rd International Seed Testing Asso-ciation-PDC, 16-19 Aug 1999, Ames, Iowa,USA.

Mun JH, Song YH, Heong K. Roderick GK. 1999.Genetic variation among Asian populations ofrice planthoppers, Nilaparvata lugens andSogatella furcifera (Hemiptera:Delphacidae):mitochondrial DNA sequences. Bull. Entomol.Res. 89:245-253.

Soriano IR, Schmit V, Brar DS, Prot J-C, Reversat G.1999. Resistance to rice root-knot nematodeMeloidogyne graminicola identified in Oryzalongistaminata and O. glaberrima. Nematol-ogy 1(4):395-398.

Sta Cruz FC, Boulton MI, Hull R, Azzam O. 1999.Agroinoculation allows the screening of ricefor resistance to rice tungro bacilliform virus.J. Phytopathol. 147(12):653-659.

Wang GL, Leung H. 1999. Molecular biology ofhost-pathogen interactions in rice diseases. In:Shimamoto K, editor. Molecular biology ofrice. Berlin: Springer-Verlag. p 201-232.

Zhang R, He X, Heong KL. 1999. Assessing im-pacts of climate change on paddy borerScirpophaga incertulas (Walker) in Guang-dong province, China. In: Zhang R, Gu D,Zhang W, Zhou C, Pang Y, editors. Proceed-ings of the International Symposium on IPM inRice-Based Ecosystems, Guangzhou, Peoples’

Republic of China. 20-24 Oct 1997.Guangzhou (China): Zhongshan University.p 245-253.

Genetic Resources Center

Cohen MB, Jackson MT, Lu BR, Morin SR,Mortimer AM, Pham JL, Wade LJ. 1999. Pre-dicting the environmental impact of transgeneoutcrossing to wild and weedy rices in Asia. In:1999 PCPC Symposium Proceedings No. 72.Gene flow and agriculture: relevance fortransgenic crops. Proceedings of a symposiumheld at the University of Keele, Staffordshire,UK, 12-14 Apr 1999. p 151-157.

Ge S, Sang T, Lu BR, De-Yuan Hong. 1999.Phylogeny of rice genomes with emphasis onorigins of allotetraploid species. Proc. Natl.Acad. Sci. 96:14400-14405.

Jackson MT. 1999. Managing genetic resources andbiotechnology at IRRI’s rice genebank. In:Cohen JI, editor. Managing agricultural bio-technology—addressing research program andpolicy implications. The Hague, The Nether-lands: International Service for National Agri-cultural Research (ISNAR), and UK: CAB In-ternational. p 102-109.

Naredo MEB, Juliano AB, Lu BR, de Guzman F,Jackson MT. 1998. Responses to seed dor-mancy-breaking treatments in rice species(Oryza L.). Seed Sci. Technol. 26:675-689.

Parsons B, Newbury HJ, Jackson MT, Ford-LloydBV. 1999. The genetic structure and conserva-tion of aus, aman and boro rices from Bangla-desh. Genet. Res. Crop Evol. 46:587-598.

Thurston HD,Salik J, Smith M, Trutmann P, PhamJL, McDowell R. 1999. Traditional manage-ment of agrobiodiversity. In: Wood D, LenneJM, editors. Agrobiodiversity: characteriza-tion, utilization and management. CABI. p211-244.

Zhu JH, Stephenson P, Laurie DA, Li W, Tang D,Jackson MT, Gale MD. 1999. Towards ricegenome scanning by map-based AFLP finger-printing. Mol. Gen. Genet. 261:184-295.


Plant Breeding, Genetics, and Biochemistry

Aggarwal RK, Brar DS, Nandi S, Huang N, KhushGS. 1999. Phylogenetic relationships amongOryza species as revealed by AFLP markers.Theor. Appl. Genet. 98:1320-1328.

Alam MF, Datta K, Vasquez A, Tu J, Virmani SS,Datta SK. 1999. Transgenic insect resistantmaintainer line (IR68899B) for improvementof hybrid rice. Plant Cell Rep. 18:572-575.

Alam MF, Datta K, Abrigo E, Oliva N, Tu J,Virmani SS, Datta SK. 1999. Transgenic in-sect-resistant maintainer line (IR68899B) forimprovement of hybrid rice. Plant Cell Rep.18:571-575.

Arakawa A, Fukuta Y, Yagi T, Tamura K, Kudo K.1999. QTL analysis of awn length in riceMilyang23/Akihikari recombinat Inbred linesusing DNA marker. Hokuriku Crop Sci. 34:94-96.

Ashikawa I, Fukuta Y, Tamura K, Yagi T. 1999.Application of AFLP technique that uses non-radioactive fluorescent primers to the detectionof genetic diversity in Japanese rice cultivarsand cloning of DNA sequences derived from anIndica genome. Breed. Sci. 49:225-231.

Chareonpornwattana S, Krishnarajapuran VT,Wang L, Datta SK, Panbangred W,Muthukrishnan S. 1999. Inheritance, expres-sion, and silencing of a chitinase transgene inrice. Theor. Appl. Genet. 98:371-378.

Cho Y-C, Shui Y-S, Ahn S-N, Gregorio GB, KangK-H, Brar DS, Moon HP. 1999. DNA finger-printing of rice cultivars using AFLP andRAPD markers. Korean J. Crop Sci. 44:26-31.

Datta K, Datta SK. 1999. Transformation of rice viaPEG-mediated DNA uptake into protoplasts.In: Hall RD, editor. Methods in molecular bi-ology, plant cell culture protocols. Vol. 3. NewJersey: Humana Press, Inc. p 335-347.

Datta K, Muthukrishnan S, Datta SK. 1999. Expres-sion and function of PR-protein genes intransgenic plants. In: Datta SK, MuthukrishnanS, editors. Pathogenesis-related proteins inplants. USA: CRC Press. p 261-277.

Datta K,Velazhahan R, Oliva N, Mew T, Khush GS,Muthukrishnan S, Datta SK. 1999. Over ex-pression of cloned rice thaumatin-like protein(PR-5) gene in transgenic rice plants enhancesenvironmental friendly resistance to

Rhizoctonia solani causing sheath blightdisease. Theor. Appl. Genet. 98:1138-1145.

Datta SK, Muthukrishnan S, editors. 1999.Pathogenesis-related proteins in plants. USA:CRC Press.

Datta SK. 1999. Transgenic rice: development,products, acceptance and economic impact. In:Plant biotechnology and in vitro biology in the21st century. The Netherlands: Kluwer Aca-demic Publisher. p 737-740.

Datta SK. 1999. Transgenic cereals: Oryza sativa(rice) In: Vasil IK, editor. Molecular improve-ment of cereal crops. Vol. 5. The Netherlands:Kluwer Academic Publisher. p 149-187.

Fukuta Y, Fujita Y, Tamura K, Yagi T. 1999. QTLanalysis for resistance to rice leaf blast usingMilyang 23/Akihikari recombinant inbredlines. Hokuriku Crop Sci. 34:90-93.

Fukuyama T, Sasahara H, Fukuta Y. 1999. Varia-tion of vascular bundle system corresponds toindica, tropical- and temperate-japonica differ-entiation of Asian rice (Oryza sativa L.). Breed.Sci. 49:15-19.

Graham RD, Senadhira D, Beebe S, Iglesias L,Monasterio I. 1999. Breeding for micronurientdensity in edible portions of staple food crops:conventional approach. Field Crop Res. 60:57-80.

Jelodar NB, Blackhall NW, Hartman TPV, Brar DS,Khush GS, Darvey MR, Cocking EC, PowerJB. 1999. Intergeneric somatic hybrids of rice[Oryza sativa L. (+) Porteresia coarctata(Roxb.) Tateoka]. Theor. Appl. Genet. 99:570-577.

Jensen LB, Courtois B, Olofsdotter M, Shen LS,Mauleon RP, Li ZK. 1999. Locating genes con-trolling allelopathic effects againstEchinochloa crus-galli in upland rice. In: Pro-ceedings of the Second World Congress onAllelopathy—Critical Analysis and FutureProspects, Thunder Bay, Canada, 8-13 Aug1999. (Abstract). p 53.

Khush GS. 1999. New plant type of rice for increas-ing the genetic yield potential. In: Nanda JN,editor. Rice breeding and genetics–Researchpriorities and challenges. Enfield, New Hamp-shire (USA): Science Publishers, Inc. p 99-108.

Khush GS, Bennett J, Datta SK, Brar DS, Li Z.1999. Advances in rice genetics and biotech-nology. In: Proceedings of the 19th Session of


the International Rice Commission, Cairo,Egypt, 7-9 Sep 1998. International Rice Com-mission. Rome: FAO. p. 64-76.

Khush GS, Sombilla MA, Hossain M. 1999. Live-stock, ethics and quality of life in Asia: thefood-feed dimension of grain demand. In:Hodges J, Han IK, editors. Livestock, ethicsand quality of life. Wallingford, UK: CABIPublishing. p 175-198.

Li ZK, Luo L, Tabien R, Mei H, Paterson AH, ZhaoXH, Zhong DB, Wang DL, Wang YP, YingCS, Stansel JW. 1999 A ‘defeated’ resistancegene acts as a QTL against a virulent strain ofXanthonomas oryzae pv. oryzae. Mol. Gen.Genet. 261:58-63.

Li ZK, Paterson AH, Pinson SRM, Stansel JW.1999. RFLP facilitated analysis of tiller andleaf angles in rice (Oryza sativa L.). Euphytica109(2):79-84.

Lijun L, Li ZK, Mei H, Wang D, Zhou X, Wang Y,Zhong D, Yu X, Ying C, Paterson A. 1999.Heterosis performance and parental genetic di-versity. Chin. J. Rice Sci. 13(1):6-10.

Mei HW, Li ZK, Wang YP, Yu XQ, Zhong DB,Luo LJ, Ying CS, Paterson AH. 1999 Classifi-cation of the recombinant inbred lines fromLemont/Teqing cross based on the six indica-japonica differentiation characteristics. Chin. J.Rice Sci. 11(4):193-197.

Mei HW, Luo LJ, Wang YP, Yuan XP, Zhao XH,Zhong DB, Yu XQ, Wang DL, Ying CS,Paterson AH, Li ZK. 1999. QTL mapping ofhorizontal resistance to bacterial blightXanthomonas oryzae pv. oryzae in rice. ActaGenet. Sin. 26(4):345-349.

Peng S, Cassman KG, Virmani SS, Sheehy J, KhushGS. 1999. Yield potential trends of tropical ricesince the release of IR8 and the challenge ofincreasing rice yield potential. Crop Sci.39:1552-1559.

Reddy PM, Aggarwal RK, Ramos MC, Ladha JK,Brar DS, Kouchi H. 1999. See Soil and WaterSciences.

Sanchez AC, Khush GS. 1998. Inheritance and link-age relationships of twenty-one genes in rice,Oryza sativa L. SABRAO J. 30:51-60.

Sanchez AC, Ilag LL, Yang DC, Brar DS, AusubelF, Khush GS, Yano M, Sasaki T, Li ZK, HuangN. 1999. Genetic and physical mapping of

xa13, a recessive bacterial blight resistancegene in rice. Theor. Appl. Genet. 98:1022-1028.

Sasahara H. Fukuta Y, Fukuyama T. 1999. Mappingof QTLs for vascular bundle system and spikemorphology in rice, Oryza sativa L. Breed. Sci.49:75-81.

Singh KN, Nandi R, Shanmugasundram P,Sadasivam S, Huang N, Brar DS, Khush GS.1999. High-resolution DNA fingerprinting ofIndian rice (Oryza sativa L.) varieties by am-plified fragment length polymorphism.Euphytica 46:427-433.

Soriano IR, Schmit V, Brar DS, Prot JC, ReversatG. 1999. Resistance to rice root-knot nematodeMeloidogyne graminicola identified in Oryzalongistaminata and O. glaberrima. Nematol-ogy 14:395-398.

Tamura K, Fukuta Y, Hirae M, Oya S, Ashikawa I,Yagi T. 1999. Mapping of the Grh1 locus forgreen rice leafhopper resistance in rice usingRFLP markers. Breed. Sci. 49:11-14.

Virk PS, Pooni HS, Syed NH, Kearsey MJ. 1999.Fast and reliable validation of lines and crossesusing microsatellite markers in Arabidopsisthaliana. Theor. Appl. Genet. 98:462-464.

Social Sciences

Ballabh V, Pandey S. 1999. Transitions in rice pro-duction systems in Eastern India: evidencesfrom two villages in Uttar Pradesh. Econ. Polit.Week.

Estudillo JP, Fujimura M, Hossain M. 1999. Newrice technology and comparative advantage inrice production in the Philippines. J. Dev. Stud.35(5):162-184.

Godilano EC, DeGloria SD. 1998. Spatial analysisframework for community-based watershedmanagement in the Philippines. Philipp. Re-mote Sensing Newsl. 9(1).

Hayami Y, Marciano E, Kikuchi M. 1998. Did Phil-ippine land reform reduce inequality? A per-spective from a Laguna village. J. Agric. Econ.Dev. 26(1 and 2):17-38.

Hossain M. 1999. Long-term outlook of the de-mand-supply balance for staple grains in Asiandeltas: implications for food security strategy.In: Proceedings of the First International Sym-


posium on Sustainable Ecosystem Manage-ment, Planetary Garden 99, Chambery, 14-18Mar 1999. p 348-357.

Hossain M. 1999. Longterm perspective of the de-mand-supply balance for rice in Asia: implica-tions for technological challenges. In: Horie Tet al., editors. Proceedings of the InternationalSymposium on World Food Security and CropProduction Technologies for Tomorrow. KyotoUniversity, 8-9 Oct 1999. p 31-39.

Hossain M. 1999. Grassroots organizations for pro-moting sustainable agriculture and food secu-rity: the experience of Grameen Bank in Bang-ladesh. In: Balasubramanian V, Ladha JK,Denning GL, editors. Resource management inrice systems: nutrients. The Netherlands:Kluwer Academic Publishers. p 297-311.

Hossain M, Sombilla M. 1999. Emerging trends indemand for cereal crops. In: Bindraban PS etal., editors. Food security at different scales:demographic, biophysical and socioeconomicconsiderations. Wageningen: DLO ResearchInstitute for Agrobiology and Soil Fertility andThe C.T. de Wit Graduate School for Produc-tion Ecology.

Hossain M, Sombilla M. 1999. World grains mar-ket: implications for a food security strategy.In: Cabanilla L, Paunlagui M, editors. Food se-curity in the Philippines. Institute of StrategicPlanning and Policy Studies in cooperationwith UP Center for Integrative and Develop-ment Studies. University of the Philippines.

Kinh NN, Kam SP, Hoanh CT, Castella JC. 1999.Ecoregional approaches for natural resourcemanagement in the Red River Basin, Vietnam.Summary Proceedings of a technical workshopheld in MARD Hanoi on 9-10 Nov 1998.MARD-IRRI, Los Banos. 42 p.

Kinh NN, Teng PS, Hoanh CT, Castella JC, editors.1999. Towards an ecoregional approach fornatural resource management in the Red RiverBasin of Vietnam. Ministry of Agriculture andRural Development, Hanoi, Vietnam and Inter-national Rice Research Institute, Los Baños,Philippines. 254 p.

Kinh NN, Kam SP, Hoanh CT, Castella JC. 1999.Summary proceedings of Technical Workshopon Ecoregional Approaches for Natural Re-sources Management in the Red River Basin(RRB), Vietnam. 48 p.

Lapar L, Pandey S. 1999. Adoption of soil conser-vation: the case of the Philippine uplands.Agric. Econ. 21(3):241-246.

Liew SCP, Chen CP, Kam SP, Tuong TP, MinhVQ, Lim H. 1999. Monitoring changes in ricecropping systems using space-borne SAR im-agery. Proceedings of the 1999 InternationalGeoscience and Remote Sensing Symposium.2:741-743.

Lucas MP, Pandey S, Villano RA, Culanay DR,Obien SR. 1999. Characterization and eco-nomic analysis of intensive cropping systemsin rainfed lowlands of Ilocos Norte, Philip-pines. Exp. Agric. 35:211-224.

Pandey S. 1999. Adoption of nutrient managementtechnologies for rice production: economic andinstitutional constraints and opportunities.Nutr. Cycl. Agroecosyst. 53:103-112.

Pandey S, Rajatsereekul S. 1999. Economics ofplant breeding: the value of shorter breedingcycles for rice in northeast Thailand. FieldCrops Res. 64(1/2):187-197.

Pandey S, Masicat P, Velasco L, Villano R. 1999.Risk analysis of a rainfed rice production sys-tems in Tarlac, Central Luzon, Philippines.Exp. Agric. 35:225-237.

Paris T, Singh A, Luis J, Hossain M, Singh HN,Singh S, Singh ON. 1999. Incorporating genderconcerns in participatory plant breeding andvarietal selection: preliminary results fromeastern India”. In: Ashby J, Sperling L, editors.Proceedings of the International Workshop onParticipatory Plant Breeding and GenderAnalysis.”

Roetter R, Hoanh CT. 1999. Exploring land use op-tions under multiple goals in support of naturalresource management at sub-national level. In:Kinh NN, Teng PS, Hoanh CT, Castella JC,editors. Towards an ecoregional approach fornatural resource management in the Red RiverBasin of Vietnam. Ministry of Agriculture andRural Development, Hanoi, Vietnam and Inter-national Rice Research Institute, Los Baños,Philippines. p 29-57.

Truong Thi Ngoc Chi, Price LL, Hossain M. 1998.Effect of IPM-farmer field school on the maleand female rice farmers’ insect managementknowledge and pest control practices in CanTho, Vietnam. Philipp. J. Crop Sci. 23(1): 53-58.


Wang DL, Zhu J, Li ZK, Paterson AH. 1999. Map-ping QTLs with epistatic effects and genotypex environment interactions by mixed linearmodel approaches. Theor. Appl. Genet.99:1255-1264.

Soil and Water Sciences

Adhikari C, Bronson KF, Panuallah GM, RegmiAP, Saha PK, Dobermann A, Olk DC, HobbsPR, Pasuquin E. 1999. On-farm soil N supplyand N nutrition in the rice-wheat system ofNepal and Bangladesh. Field Crops Res.64:273-286.

Agustin EO, Ortal CI, Pascua SR, Sta. Cruz PC,Padre AT, Ventura WB, Obien SR, Ladha JK.1999. Role of indigo in improving the produc-tivity of rainfed lowland rice-based croppingsystems. Exp. Agric. 35:201-210.

Alberto MCR, Arah JRM, Neue HU, Wassmann R,Lantin RS, Aduna JB, Bronson KF. 1999. Asampling technique for the determination ofdissolved methane in soil solution.Chemosphere: Global Change Sci. 2(2000):57-63.

Boling A, To Phuc Tuong, Anil Kumar Singh,Wopereis MCS. 1998. Comparative rootgrowth and soil water extraction of dry-seeded,wet-seeded, and transplanted rice in a green-house experiment. Philipp. J. Crop Sci.23(1):45-52.

Briones Jr. AM, Reichardt W. 1999. Estimatingmicrobial population counts by “most probablenumber” using Microsoft Excel. J. Microbiol.Meth. 35:157-161.

Chalk PM, Ladha JK. 1999. Estimation of legumesymbiotic dependence: an evaluation of tech-niques based on 15N dilution. Soil Biol.Biochem. 31:1901-1917.

Gumtang RJ, Pampolino MF, Tuong TP. 1999.Ground water dynamics and quality under in-tensive cropping systems. J. Exp. Agric.35:153-166.

Kirk GJD. 1999. A model of phosphate solubiliza-tion by organic anion excretion from plantroots. Eur. J. Soil Sci. 50:369-378.

Kirk GJD, Santos EE, Findenegg GR. 1999. Phos-phate solubilization by organic anion excretionfrom rice (Oryza sativa L.) growing in aerobicsoil. Plant Soil 211:11-18.

Kirk GJD, Santos EE, Santos MB. 1999. Phosphatesolubilization by organic anion excretion fromrice growing in aerobic soil: rates of excretionand decomposition, effects on rhizosphere pH,and effects on phosphate solubility and uptake.New Phytol. 142:185-200.

Kouchi H, Takane K, So R, Ladha JK, Reddy PM.1999. Rice Enod40: isolation and expressionanalysis in rice and transgenic soybean rootnodules. Plant J. 18:121-129.

Kouchi H, Takane K, So RB, Ladha JK, Reddy PM.1999. Rice ENOD40: Isolation and expressionanalysis in rice and transgenic soybean rootnodules. Plant J. 18:121-129.

Kronzucker HJ, Siddiqi MY, Glass ADM, KirkGJD. 1999. Nitrate-ammonium synergism inrice: a subcellular flux analysis. Plant Physiol.119:1041-1045.

Kundu DK, Ladha JK. 1999. Sustaining productiv-ity of lowland rice soils: issues and options re-lated to N availability. Nutr. Cycl.Agroecosyst. 53:19-33.

Malarvizhi P, Ladha JK. 1999. Influence of avail-able nitrogen and rice genotype on associativedinitrogen fixation. Soil Sci. Soc. Am. J. 63:93-99.

Pascua SR,Ventura W, Agustin EO, Padre AT, Va-lencia DA, Marcos TF, Sta. Cruz PC, ObienSR, Ladha JK. 1999. Yield trends and apparentnutrient balances in intensified and diversifiedrice-based cropping systems. Exp. Agric.35:181-199.

Reddy PM, Aggarwal PK, Ramos MC, Ladha JK,Brar DS, Kouchi H. 1999. Widespread occur-rence of the homologues of the early nodulin(ENOD) genes in Oryza species and relatedgrasses. Biochem. Biophys. Res. Commun.258:148-154.

Reddy PM, Aggarwal RK, Ramos MC, Ladha JK,Brar DS, Kouchi H. 1999. Widespread occur-rence of the homologues of the early nodulin(ENOD) genes in Oryza species and relatedgrasses. Biochem. Biophys. Res. Commun.258:148-154.

Revsbech NP, Pedersen O, Reichardt W, Briones A.1999. Microsensor analysis of oxygen and pHin the rice rhizobia under field and laboratoryconditions. Biol. Fertil. Soils 29:379-385.


Tuong TP, Bhuiyan SI. 1999. Increasing water useeficiency in rice poduction: farm level perspec-tives. Agric. Water Manage. 40:117-122.

Wihardjaka A, Kirk GJD, Abdulrachman S,Mamaril CP. 1999. Potassium balances inrainfed lowland rice on a light-textured soil.Field Crops Res. 64:237-247.

Rice research seminars

Disease resistance, rice mutants, and functionalgenomics. Dr. H. Leung.

The ecology of plant virus disease. Dr. M. Thresh,chair, Virus Epidemiology Committee, Interna-tional Society of Plant Pathologists, UK.

Plant breeding perspectives: balanced integration ofapproaches. Dr. A. Ashri, Faculty of Agricul-ture, The Hebrew University of Jerusalem, Is-rael.

Rice research development through Thai-IRRI col-laboration. Dr. B. Somrith, candidate, IRRI li-aison scientist (consultant) for Thailand.

Operationalizing the ecoregional approach in theuplands of the Red River Basin. Dr. J.-C.Castella.

Juggling science and management: seven years inthe IRRI circus. Dr. R.S. Zeigler.

A balancing act: nutrient equilibrium for sustainablecrop production. Dr. J.K. Ladha.

Virginia tech’s involvement in global food security,food safety, and natural resources managementissues. Dr. S.K. De Datta, director, Office ofInternational Research and Development, andassociate dean, College of Agriculture and LifeSciences, Virginia Tech, Blacksburg, Virginia,USA.

Temporal and spatial variability of optimal nitrogenapplications. Dr. D. Dawe.

The road to impact. Dr. A. Dobermann.Evaluation, evaluators, and evaluation culture. Dr.

G.T. Castillo.Fertile feedback: an evolutionary approach to

achieving impact. Mr. B. Douthwaite.Proprietary property: what is it and why do I care?

Mr. D. Kryder, intellectual property specialist,International Service for the Acquisition ofAgri-Biotech Applications New York, USA.

Spatial analysis framework for community-basednatural resource management in the Philip-

pines, implications to new CGIAR mission. Dr.S.C. Godilano.

The universe, the evolution of the perverse, and arice problem. Dr. J.E. Sheehy.

Transgenic rice: lab to field, constraints and impact.Dr. S.K. Datta.

Farmer participatory research in rice technologydevelopment and dissemination. Dr. V.Balasubramanian.

Conceptual and methodological issues in rice fieldbiodiversity research: lessons from inverte-brates. Dr. K.G. Schoenly.

Changing rice production situations in lowland riceand implications to plant protection. Dr. S.Savary.

The role of an R&D network in a CGIAR center: thecase of CIP-UPWARD. Dr. D.M. Campilan,social scientist and UPWARD network coordi-nator, International Potato Center.

Rice and the Philippine media: getting through. Mr.J.C. Burgos, Jr., publisher-editor, We Forum,Quezon City, Philippines.

To direct-seed or not to direct-seed: some economicconsiderations. Dr. S. Pandey.

Introducing—the new International Rice ResearchNotes (IRRN): content, creed, and continuingconundrums. Dr. M.B. Cohen.

INM research in Cambodia: the end of one phaseand the beginning of another. Dr. P. White.

Everything you always wanted to know about theIRRI Library…but were afraid to ask. Mr. I.Wallace.

Food security in Asian countries in the 21st century.Dr. K. Ohaga, Professor, Department of GlobalAgricultural Sciences, Graduate School of Ag-ricultural and Life Sciences, The University ofTokyo, Japan.

SysNet methodology development for agriculturalland-use planning in South and Southeast Asia.Dr. R. Roetter.

Molecular markers for common beans at CIAT. Dr.S. Beebe, common bean breeder, CentroInternacional de Agricultura Tropical, Cali,Colombia.

Small RNA viruses of insects: Helicoverpaarmigera stunt virus and new transgenic strate-gies for pest control. Dr. K. Gordon, Biotech-nology Program, Commonwealth Scientificand Industrial Research Organization Entomol-ogy, Canberra, Australia.


Bacillus thuringiensis: an overview. Dr. R. Frutos,Centre de coopération intenationale en recher-che agronomique pour le développement,Montpellier, France.

Pesticides—rumors, gossip, and a few facts. Mr. C.Meek, expert consultant on agrochemical ap-plications, Experiment Station.

Division seminars

Agronomy, Plant Physiology,and Agroecology

System of rice intensification. Dr. N. Uphoff, direc-tor, Cornell International Institute for Food,Agriculture, and Development, Cornell Uni-versity, Ithaca, New York, USA.

Plant-available silicon in slag fertilizer and soil. Dr.N. Kato, visitor collaborator, Laboratory ofLowland Soils, Tohoku National AgriculturalExperiment Station, Omagari, Akita, Japan.

Changes in root water uptake power of water-stressed upland rice. Ms. K. Okada.

Integrated on-farm diagnosis on upland rice crop innorthern Thailand. Dr. G. Trebuil and Dr. K.Van Keer.

Progress toward natural weed suppression in riceand an overview of rice research objectives atthe USDA-ARS Dale Bumpers National RiceResearch Center, Stuttgart, Arkansas, USA. Dr.D. Gealy, plant physiologist, USDA-ARS,Stuttgart, Arkansas, USA.

Upland rice-based research in northern Laos: stabi-lizing swidden systems. Dr. K. Fahrney.

CREMNET

Role of farmer participatory research in rice tech-nology development and dissemination. Dr. V.Balasubramanian.

Entomology and Plant Pathology

Polycistronic expression units for increased andselectable expression of transgenes in rice forengineered resistance to RTD. C. Henrich, In-stitute of Plant Science, ETH, Zurich, Switzer-land.

Dissecting disease resistance pathway by forwardand reverse genetics: progress and application.Dr. Wu Changjian.

Bacterial populations associated with rice seed. Mr.B. Cottyn.

Genetic diversity of the rice blast pathogen and theevolution of races. Dr. J. Correll, visiting sci-entist from the University of Arkansas.

Molecular characterization of tungro biologicalvariants. Dr. O. Azzam and Dr. P. Cabauatan.

Attempts to elucidate the role of rice dwarf virusgenes in multiplication in cells. Dr. I. Uyeda,collaborator, IRRI-Japan Shuttle Research.

Some important issues in stem borer managementand the potential of rice plants to compensatefor insect pest injury. Dr. E. R.-Sanchez.

Using conserved motifs of plant resistance genes tocharacterize rice functional genetic diversity.Dr. Zonghua Wang.

Simulation modeling of rice yield losses due topests, diseases, and weeds. Dr. L. Willocquetand Ms. L.C. Fernandez.

Rice sheath blight research: the disease, its cycleand importance—Dr. S. Savary; Epidemiogy—N. Castilla; Biological control—Dr. T.W.Mew; Crop establishment methods—Dr. L.Willocquet; Transgenic rice for resistance—K.Datta.

Exploring synteny between rice and wild rice. Prof.R. L. Philips, regent professor, Department ofAgronomy and Plant Genetics, University ofMinnesota, USA.

Research needs on seed pathology in developingcountries: a future prospective. Dr. T.W. Mew.

Bt rice for control of yellow stem borer: initial im-pressions. Dr. J.S. Bentur.

Evaluation of a cryIAb -transformed Iranian ricevariety against lepidopterous pests and crylAbresistance development in striped stem borer.Dr. F. Alinia.

Prey-mediated and direct effects of Bt proteins onimmature Chrysoperla carnea. Dr. A. Hilbeck,Swiss Federal Research Station forAgroecology and Agriculture.

Engineering resistance against bacterial blight ofrice. Dr. Wen Yuan Song, Plant Pathology De-partment, University of California Davis, USA.


Plant Breeding, Genetics, and Biochemistry

Biotechnology for enhancement of gall midge re-sistance in rice: present status. Dr. S. Katiyar.

Genetically modified organisms: issues and con-cerns. B.S. Ahloowalia, Agriculture and FoodDevelopment Authority, Dublin, Ireland.

Cytogenetic and molecular analysis of Oryza sativa× O. australiensis and O. sativa × O.brachyantha derivatives. F.M. Abbasi.

Biological significance of programmed cell death inrice. Prof. H. Uchimiya, Institute of Molecularand Cellular Biosciences, University of Tokyo,Japan.

Positional cloning and phylogeny of rice blast re-sistance gene, Pi-b. Dr. S. Kawasaki, NationalInstitute of Agrobiological Resources,Kannondai, Tsukuba, Ibaraki, Japan.

Genetic engineering of wheat for improved phos-phate bioavailability. Dr. P.B. Holm, DanishInstitute of Agricultural Sciences, Denmark.

Stability of performance in plant breeding. Dr. M.S.Kang, Louisiana State University, USA.

Plastid transformation: an ecofriendly approach forcrop improvement. Dr. S.R. Sikdar, Bose Insti-tute, Calcutta, India.

Nutritional and eating quality of rice. Dr. I. Tetens,Research Department of Human Nutrition, TheRoyal Veterinary and Agricultural University,Denmark.

Studies of mineral bioavailability. Dr. M. Hansen,Research Department of Human Nutrition, TheRoyal Veterinary and Agricultural University,Denmark.

Enhancing nutritional protein content in crops: re-sults from sweet potato. Dr. C.S. Prakash,Tuskegee University, USA.

Partial resistance to rice blast and current status ofrice breeding for blast control in Japan. Dr. S.Koizumi, Ms. K. Zenbayashi, and Mr. N.Yokogami, Tohoku National Agricultural Ex-periment Station, Japan.

Management, display, and analysis of expressed se-quence tag (EST) data for the Triticeae in thegraingenes database. Dr. G.R. Lazo, USDA/ARS Western Regional Research Center, Cali-fornia, USA.

Utilizing temperature japonica germplasm for tropi-cal cultivation. Mr. J. Chavez.

Genetic diversity within and between maintainerand restorer lines used to develop tropical ricehybrids in the Philippines. Dr. Weijun Xu.

Social Sciences

Multi-temporal analysis of flooded areas in theMekong River Delta using radar remote sens-ing. Ms. A. Alvaran.

The impact of El Nino in rice production: a case ofBulacan. Ms. S. Valencia.

Assessing the impact of agricultural research onpoverty alleviation. Ms. C. Diaz and Dr. C.Edmonds.

Diversification into fruit production on lowland ricefarms in Thailand: a multiperiod linear pro-gramming analysis. Dr. S. Phuphak.

Gender and economics: its relevance to rice re-search. Dr. S. Floro.

The effects of overseas remittance income on low-land rice producers: a research plan. Dr. S.Graw.

A socioeconomic study of land use and crop pro-duction systems in the uplands of northern Vi-etnam (household survey in Ha Giang Prov-ince, 1998). Dr. D.E. Pemsl.

The conditions of farmer participation in irrigationmanagement: a cross section analysis for thePhlippines. Dr. Y. Hayami and Dr. M. Fujita.

Effect of improved technology on rice productionand impact on income distribution and povertyalleviation: a case of Vietnam. Mr. Tran Thi Ut.

Should developing countries invest more in lessfavored areas? An empirical analysis from ru-ral India. Dr. P. Hazell, director, InternationalProtection and Technology Division, Interna-tional Food Policy and Research Institute,Washington, D.C., USA.

Soil and Water Sciences

Design and management of the RTDP databases (asharing of lessons learned). Mr. G. Simbahan.

Genetic diversity of arbuscular-vesicular fungi andtheir application in Japan. Dr. M. Saito, Na-tional Grassland Research Institute, Tochigi,Japan.

Water and straw management long term study:insights, constraints, and potentials. Ms. Ma. J.Aduna.

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Aagricultural diversification 99Agricultural Research Center of Sarawak 107agrohydrology 38agromorphological traits 112alleles 8, 9, 10, 49, 52, 110, 112allelopathy 52, 53, 61Aphelenchoides besseyi 115apomixis 10aquatic legume 108ASEAN standard seed treatment 115, 116asexual embryo 10Asian Rice Biotechnology Network 78, 125Atypena formosana 21, 22Azolla 108

B

BAC library 12, 78, 79, 80bacterial blight resistance 83, 84, 85tbacterial leaf streak 115Bastar Plateau 110belief model 20biofertilizer germplasm 108bioinformatics 99, 130biological control 21biosystematic relationships 109biotechnology 78, 103biotic constraints 64Bipolaris oryzae 115blast 19, 20, 23, 48, 87t, 90, 112, 113, 114tblast management 86, 87blast resistance 53, 54, 61blue-green algae 108Bolivia 112Brazil 53, 61, 112, 113, 168brown spot 19Bt-endotoxin 81

C

Cagayan Valley 112Cambodia-IRRI-Australia Project 120, 123, 124, 162Cambodian Agricultural Research and Development

Institute 121

candidate genes 53, 54, 61.CARDI (see Cambodian Agricultural Research and Development Institute)Catanduanes 107CIAP (see Cambodia-IRRI-Australia Project)CIAT (see International Center for Tropical Agriculture)CIMMYT (see International Maize and Wheat Improve- ment Center)Colombia 113competitive ability 52consortium 61, 64, 91contig 80fcrop establishment methods 22crop intensification 122crossability 108crown sheath rot 19cytoplasmic male sterility 5

D

data management 23, 106, 108, 139, 140data management system 106,108,113, 114, 115, 140deepwater 32, 112diversity in resistance 87diversity of upland systems 48, 99DLL (see dynamic link library)DMC1 12DMS (see data management system)drought 26, 28, 44, 48dynamic link library 113,114

E

Echinochloa 52, 115ecoregional approach 98ecosystem-based nurseries 112ELISA (see enzyme-linked immunosorbent assay)embryo 10, 11, 12endosperm 11enzyme-linked immunosorbent assay 15,16,21erosion risk 99, 101t, 102f

Keyword index 173

F

false smut 19FAO (see Food and Agriculture Organization)farmer-participatory varietal selection 60, 61farming systems 34, 60, 121, 133Fe density (see Iron density)field water balance 22flood-prone rice 64, 76flooding tolerance 64Food and Agriculture Organization 108food security 4, 54, 60, 61, 103, 120, 122France 60functional genomics 48, 60, 81, 89, 99, 103, 157Fusarium moniliforme 115Ggender concerns 33, 93gene flow 84, 88genealogy 95, 96, 98, 114, 115Genealogy Management System 113, 114genepool 78gene sequence 81, 82t, 83tgenetic diversity 8, 9, 10, 86, 96, 109, 110, 112, 113, 114t, 116, 151, 153, 154, 158geographic information system 23, 27, 29, 99germplasm characterization 108, 116germplasm collection 106germplasm conservation 34,108germplasm improvement 16,26,33, 44, 45, 48,64,78, 93, 94, 95, 99germplasm multiplication 107germplasm utilization 10, 14, 53, 61, 66, 96, 103GIS (see geographic information system)glutinous varieties 86, 87, 107, 122GMD (see grain mineral density)GMS (see Genealogy Management System)grain mineral density 66, 67,68, 69grain quality 6, 16, 58, 90, 92, 96, 98, 123grain yield 10, 13, 14t, 16, 36t, 40, 51, 58green leafhopper 14, 15, 16, 22GRIN 114

Hhead rice recovery 93, 98, 123

IICIS (see International Crop Information System)IITA (see International Institute of Tropical Agricul- ture)improved rice varieties 38, 93, 94tINGER (see International Network for Genetic Evaluation of Rice)INGER Information System 113INGER nurseries 105, 112, 115INGERIS 113integrated pest management 24, 120, 121, 132, 133,International Center for Tropical Agriculture 112, 114International Crop Information System 113, 114, 127, 140

International Institute of Tropical Agriculture 112, 114International Network for Genetic Evaluation of Rice 14, 196, 112, 113, 115, 116, 125, 140International Rice Blast Nursery 105, 113international Rice Genebank Collection 107International Rice Genebank Collection Information System 108, 116International Rice Information System 106, 113, 114, 115, 116, 140International Maize and Wheat Improvement Center 18, 114interplanting 86, 87IPM (see integrated pest management)IR64 bacterial artificial chromosome 78iron density 66IRBN (see International Rice Blast Nursery)IRGC accessions 15, 109, 114IRGCIS (see International Rice Genebank Collection Information System)Irian Jaya 106, 108IRIS (see International Rice Information System)irrigated rice 74 53, 99, 115, 124irrigated rice ecosystem 4, 21, 23, 24, 32, 45, 52, 112, 121, 122, 133irrigation 39, 44, 51, 96Ischaemum rugosum. 115Italy 112

K

Kachin 107Kayah 107Kayin 107kinase domain 79Korea 114, 115, 129t, 130t, 131t

L

land use planning 78LaoRIS 108Laos 93, 94, 95, 96, 97, 115leaf scald 115long-term experiments 16low-cost technologies 124

M

marker-aided selection 48, 52, 65, 78, 85, 139market integration 61meiosis 11, 12micronutrients 43, 66microsatellite analysis 112mixed diet 22multiscale approach 99

N

N uptake 40N2-fixing bacteria 45, 108national rice research network 121natural resource management 18, 78, 98, 103National Seed Storage Laboratory 108


near-isogenic lines 14, 15, 49, 86Nepal 18, 97, 107, 113t, 128t, 129t, 130t, 131tNepal Agricultural Research Council 107new plant type 4, 5, 13nif gene 89Nigeria 112NSSL (see National Seed Storage Laboratory)nucellin gene 11nucellus 11

Oon-the-job training 7, 108O. globerrima 107, 108O. longiglumis 106, 109, 1104 111fO. longistaminata 54, 55, 56, 57, 107, 108, 109O. meridionalis 106, 109O. minuta 85O. nivara 107O. officinalis 106O. ridleyi 109, 110t 111fO. rufipogon 17, 54, 55, 56, 57, 106, 107O. sativa 54, 55, 56, 57, 107, 108ORYZA model 38

PP deficiency 69P uptake 45, 70Pakistan 18, 94t, 95t, 97t, 113t, 114, 128t, 130t, 131tPalawan 9, 107panicle blast 19participatory varietal selection 60, 61perenniality 54perenniality genes 55pest management decisions 20physical map 77, 78, 79, 80potential yield 14, 38, 39poverty 4, 48, 60, 78, 93, 103, 120problem soils 112promoter 11, 12, 81pyramiding genes 85

Qquantitative trait loci 48, 52, 71-74f, 78Quirino 107

Rrainfed lowland ecosystem 28, 35,. 58, 97, 124rainfed lowland rice 26, 32, 35t, 38, 44, 45, 112, 121, 122, 124Rainfed Lowland Shuttle Breeding Program 115Rakhine 107randomly amplified polymorphic DNA markers 79, 109, 111fRAPD markers (see randomly amplified polymorphic DNA markers)recombinant inbred lines/population 53,69, 71-74f, 79REE5 12relative P uptake 70relative P use efficiency 70

relative shoot dry weight 69, 70, 75t, 76relative tillering ability 69, 70, 75t, 76resistance genes 15, 61resistance gene analogs 87Phizobium 89, 108rice blast 86root system 13, 14, 48, 49, 51RTSV resistance 14, 15

S

Sabah 107Sarocladium oryzae 19, 115, 116seed health 90, 116Seed Health Unit 106, 115, 116seedling blight 115semidwarfism gene 50, 96Senegal 112Shan 107Shan You 63 81, 83sheath blight 19sheath rot 19, 115, 116simple sequence length polymorphism 70SINGER (see Systemwide Information Network for Genetic Resources)Sitophilus granarius 115socioeconomic diversity 58soil fertility 41, 121, 123soil organic matter 17, 41, 139spatial distribution 27, 32, 34f, 99, 100fspatial surface analysis 27spider 21, 22stem borers 20, 78, 140Stern rot 19stem sap 13, 14stress-oriented nurseries 112sun drying 123Surigao del Sur 107Surinam 108, 112survival 19, 22, 554 56, 57, 124sustainability 18, 19, 23, 25, 40, 41, 43, 47, 48, 60, 61, 64, 99, 122SysNet (see Systems Research Network for Ecoregional Land Use Planning in Tropical Asia)Systems Research Network for Ecoregional Land Use Planning in Tropical Asia 18, 78, 127t, 128tSystemwide Information Network for Genetic Re- sources 114

T

technology adoption 29, 78terminal sequencing 78Thailand 90, 914 93, 94t, 95, 97t, 98, 99Tilletia barclayana 115trainees 128t, 129t, 130t, 131ttraining 120, 121, 122, 126, 138, 139training courses 23, 129, 132, 140ttraining materials 90, 130, 133training methodology 129transgenic plants 78, 81, 84

Keyword index 175

tungro 14, 15, 16, 17, 23, 87, 88, 112, 115, 140tungro resistance 14, 15, 16, 17, 86, 88tungro virus 16, 115

Uupland ecosystem 32, 48, 53, 54, 58, 60, 61, 66, 99, 112, 121, 122, 138upland rice 48, 53, 54, 55, 56, 58, 594 60, 61, 99, 107, 113, 121upland weeds 60, 61USA 52, 114

Vvector resistance 1.6vertical leaching 65

W

Wagwag 112WARDA (see West Africa Rice Development Association)watei-balance model 26, 27, 29weed competitiveness 36t, 61weed control 48weed suppressive cultivars 52weeds 19, 37, 43, 60West Africa Rice Development Association 112wheat 10, 16,17, 18, 19, 35, 86, 133wild rices 108, 109

Xxa5 gene 79, 80, 85, 86Xa7 gene 86xa13 gene 85,86Xa2l gene 83, 84, 85, 86

Y

yield decline 17, 39yield stability 32, 38, 39, 56yield trends 16, 17

Documents

Program Report for 1999