International Rice Research Notes Vol.19 No.4

International Rice Research Notes

The International Rice Research Notes (IRRN) expedites communication among scientists concerned with the development of improved technology for rice and rice- based systems.

The IRRN is a mechanism to help scientists keep each other informed of current rice research findings. The concise scientific notes are meant to encourage rice scientists to communicate with one another to obtain details on the research reported.

The IRRN is published quarterly in March, June, September, and December by the International Rice Research Institute; annual subject and variety indexes are also produced.

The IRRN is divided into three sections: notes, news about research collaboration, and announcements.

ISSN 0115-0944

Contents December 1994

Germplasm improvement

Genetic resources 4 A new collection of Oryza officinalis species

from western Uttar Pradesh, India

Genetics 4 Fine mapping of major genes for blast

resistance in rice

Breeding methods 5 Restorers and maintainers identified for

developing Basmati hybrids 6 Identifying maintainers and restorers for

three cytoplasmic male sterile lines of rice 7 Influence of stigma extract on in vitro

germination of pollen in Oryza species

Grain quality 8 Effect of temperature regime on grain

8 Scented rice in Jiangxi Province, China 9 Stability of rice grain quality under different

chalkiness in rice

fertilizer levels

Pest resistance—diseases 10 Inheritance of resistance to rice tungro

spherical virus in some rice cultivars

Pest resistance—insects 11 Gall midge biotype 5 identified in

11 Inheritance of whitebacked planthopper

12 Ratnagiri 3: a new gall midge-resistant, late-

Moncompu, Kerala, India

resistance

maturing variety from Maharashtra, India

lntegrated germplasm improvement—irrigated 13 Gan wan Xian 23 (Gan You Wan, SG89320):

13 Heibao, a high-yielding, good quality black

13 Peiliangyou Teqing, a new high-yielding, two-

14 Jinuo 1: a new glutinous japonica variety

a new indica rice variety with high quality

indica rice for China

line hybrid rice

with high yield and good quality

Integrated germplasm improvement—upland 15 A dual purpose rice variety: PNR381

Integrated germplasm improvement—flood-prone 16 NDGR21: a new flood-tolerant promising line

for eastern Uttar Pradesh, India

Crop and resource management

Fertilizer management—inorganic sources 16 Response to nitrogen in semidwarf scented

rice varieties

Fertilizer management—organic sources 17 Effect of methods of Sesbania aculeata

incorporation and nitrogen levels on lowland rice yield

lntegrated pest management—diseases 18 Mass culture of Beauvaria bassiana (Bals.)

Vuill. on rice hull

Integrated pest management—insects 19 Metarrhizium sp.: a new biocontrol agent for

brown planthopper management in ricefields 19 Flight activity of Spodoptera fugiperda (J. E.

Smith) in acid savanna ricefields in northeastern Colombia

20 Applying insecticides at early stage of rice cropping season may cause brown planthopper resurgence

21 Rice hull ash applied to seedbed reduces deadhearts in transplanted rice

22 Prevalent insect pests of upland rice and some associated natural enemies in southeastern Nigeria

Integrated pest management—other pests 23 Rice yield losses to finches in Hill Region,

Karnataka, India

Environment

24 Effect of plant density on methane emission from transplanted rice

Socioeconomic impact

25 Labor allocation in rice cultivation in Western Himalaya, Himachal Pradesh, India

Education and communication Page 7

26 Knowledge gap on agrochemical use in rice farming

Research methodology

27 Path analysis of focus expansion in rice sheath blight

28 Selection of protein content of upland rice grain using chlorophyll content

29 DNA fingerprinting of Xanthomonas oryzae pv. oryzae by ligation-mediated polymerase chain reaction

30 Primers for the amplification of rice tungro bacilliform virus DNA genome by polymerase chain reaction

male sterile lines in rice

mealy bug

31 Clonal propagation of thermosensitive genic

32 Greenhouse rearing and rating scale for rice

News about research collaboration

33 Identifying factors in yield decline 33 A new rainfed lowland rice research institute

in India 33 Extensive rice research training program in

Lao PDR 34 Philippine-based institutions to take responsi-

bility for international pest management training course

Announcements

34 34

35 35 36

36 36 37 37 37 37

Rice dateline Postdoctoral/project scientist positions at IRRI IRRI group training courses for 1995 International Rice Research Conference 1995 2nd International Symposium on Systems Approaches for Agricultural Development Graduate certificate in soils New IRRI publications Cornell University grants New publication Dr. H. P. Moon receives Daesan Prize Call for news

37 IRRI address Rice literature update reprint service

page 23

page 18

37

Germplasm improvement

A new collection of Oryza officinalis species from western Uttar Pradesh, India J. B. Tomar and M. N. Koppar, NBPGR Regional Station, Kilburn Colony, Hinoo House, Hinoo, Ranchi 834002, India

We collected 41 seed samples of wild rices: Oryza nivara (30), O. rufipogon (8), O. spontanea (2), and O. officinalis (I) in the Uttar Pradesh (UP) districts of Sonbhadra, Mirzapur, Allahabad, Fatehpur, Kanpur, Kanpur Dehat, Farukhabad, Badaun, Moradabad, Rampur. Bareilly, Shah,jahanpur, Sitapur, Lucknow, Barabanky, Raibareilly, Faizabad, Sultanpur, Partapgarh, Jaunpur, Azamgarh, Ghazipur, and Mau.

On this exploration, O. officinalis was collected from UP for the first time in addition to being found in areas of Saujanpur village, block Miaun, district Badaun, where rice is not traditionally grown. We characterized this accession of O. officinalis (JBT10/SP-41) for different morphological traits (see table).

Seeds were sown in pots. Data on five plants were recorded and averaged. Plant height was intermediate and culms erect. Leaves were pubescent and horizontal in angle, and the panicles long and well exserted. The spikelets had awns with no pigmentation. The ligule was acute, long, and light green. No pigmentation was observed in the leaf blade, leaf sheath

Morphological traits of Oryza officinalis collected from western Uttar Pradesh, India.

Plant height (cm) 108.5 Leaf length (cm) 42.5 Leaf width (cm) 1.5 Flag leaf length (cm) 37.0 Flag leaf width (cm) 1.6 Effective tillers/hill (no.) 12 Panicle length (cm) 276 Primary branches (no.) 7 Secondary branches (no.) 22 Spikelets/panicle (no.) 145 Spikelet length (mm) 6 Spikelet width (mm) 2.3 Awn length (cm) 5.0 Ligule length (mm) 8.0

~

base, node, and apiculus. The collar and auricle were pale green. Purple lines were observed in internodes and stigma were deeply pigmented. The sterile lemmas were light brown.

The material was not evaluated for resistance to biotic stresses and tolerance

for abiotic stresses. It may, however, have useful genes that could be used in breeding programs to improve modem rice cultivars.

The seeds have been sent for safety duplicate storage at IRRI.

markers (RG, RZ, and CDO) from Cornell University, USA, and NpB from

Fine mapping of major genes Resources, Japan. for blast resistance in rice the National Institute of Agricultural

T. W. Mew, A. Parco, S. Hittalmani, T. Inukai, R. Nelson, R. S. Zeigler, and N. Huang, IRRI

We selected at least 9 RFLP markers close to the region of the blast resistance genes in the chromosome (see table). To identify more polymorphism in the

Major genes for rice blast resistance Pi-1 (t), Pi-2 (t), and Pi-4 (t) have been mapped previously on chromosome 11, 6, and 12, respectively (Yu et al 1991, TAG 81:471-476). Pi-1 (t) is reported to be linked to RFLP marker RZ536 with a distance of 14.0 ± 4.5 cM, Pi-2 (t) is closely linked to RG64 with a distance of 2.8 ± 1.4 cM, and Pi-4 (t) is 15.4 ± 4.7 cM from RG869 and 18.1 ± 5.5 cM from RZ397. The distances between the markers and Pi-1 (t) and Pi-4 (t) are relatively large when compared with Pi-2 (t). On the other hand, flanking markers for Pi-2 (t) have not yet been determined. Tightly linked markers are needed for marker-aided breeding because they facilitate early selection of resistance genes in breeding programs.

Recently, more molecular markers were added to the rice RFLP map. With the saturation of the rice map, the probability of identifying markers more closely linked to the resistance genes has increased. In this study. we fine-mapped the three major genes using RFLP

parental survey, we included more restriction enzymes in addition to the five enzymes previously tested. Three mapping populations (F 2 and F 3 ) were derived from crosses between the recurrent parent (CO 39) and each of the these isolines. DNA samples were extracted from the fresh leaf tissues collected from the F 2 and F 3 mapping populations, CO 39, isolines, and the donor parents (see table). The DNA extracted from the parents and isolines was used for the parental survey filters, and the extracted DNA from the F 2 plants and F 3 lines (15- 20 bulked plants/line) for verification filters for linkage analysis.

inoculated with IRRI blast isolates 101 and V89013 in two separate trials. At least 15 plants per family were grown and inoculated 21 d after sowing. Disease reaction was evaluated 7 d after inoculation and individual plants of an F 3 family were scored as resistant or susceptible based on disease reaction. A family with both resistant and susceptible plants was

The F 3 mapping populations were test-

Number of plant materials, restriction enzymes, and RFLP markers used in Southern hybridization.

Blast resistance Isoline Donor parent Population Restriction RFLP markers Polymorphic gene size enzymes tested tested markers

Pi -1 (t) C101LAC Lac23 160 30 10 5

Pi -4 (t) C101PKT Pai-kan-tao 80 a 30 14 6 Pi -2 (t) C101A51 5173 120 12 9 5

a F 3 lines were used to represent the F 2 genotypes.

4 IRRN 19:4 (December 1994)

Genetic resources

Genetics

Fine-mapping of blast resistance genes.

scored as segregating. Similarly, each F 2

chromosome 12. However, we found the null allele), a score of 4 was assigned. RZ397 to be linked with Pi-4 (t) on homozygous resistant stake (because of a Pi-2 (t) on chromosome 6 and RG869 and was not easily distinguishable from the also found RG64 to be closely linked with RFLP pattern of the heterozygous stake

As reported by previous workers, we heterozygous (2). In cases where the MAPMAKER (see figure). the allele of the susceptible parent (1), or estimated using the computer program the resistant parent (3), homozygous for markers and resistance genes were the F 2 was homozygous for the allele of analysis. The genetic distances between each RFLP marker according to whether phenotype was confirmed by chi-square plant or F 3 family was given a score for Linkage of donor alleles and resistance

members to be closer to the target resistance genes in terms of map units than previously reported. We estimated RG64 to be 2.1 cM from Pi-2 (t), RG869 to be 5.4 cM, and RZ397 to be 3.3 cM away from Pi-4 (t). A new flanking marker, RG241, was identified to be 5.2 cM from Pi-4 (t). For Pi-1 (t), marker NpB181 was found to be more closely linked (3.5 cM) than RZ536 (11.4 cM). The shorter distances that we obtained may be attributed to the use of larger mapping population sizes (see table). With the identification and confirmation of these closely linked flanking markers to blast resistance genes, it is now possible to use these markers for marker- aided breeding. Marker-assisted plant selection with these flanking markers is being used for pyramiding the three major blast resistance genes.

High volume expansion through linear with four cytoplasmic male sterile (CMS) kernel elongation, fluffiness, and appeal- lines: IR58025 A, IR62829 A, PMS10 A,

Restorers and maintainers

Basmati hybrids rice. To develop acceptable Basmati selected based on pollen fertility. Crosses identified for developing ing aroma and taste characterize Basmati and PMS3 A. Thirteen genotypes were

hybrids, both parents must have these restoring ability. Genotypes were catego- cooking and eating characteristics. were repeated to confirm maintaining and

rized as effective restorers (> 80% spike- Basmati germplasm restorers, however, A. K. Sarial, V. P. Singh, and F. U. Zaman, Genetics Division, Indian Agricultural have not been available. let fertility), partial restorers (21-79% Research Institute (IARI), New Delhi 110012, India

We crossed 26 genotypes possessing

Table 1. Fertility restoration and sterility maintenance ability of improved Basmati genotypes. a

spikelet fertility), and maintainers Basmati grain and cooking characteristics (< 1% spikelet fertility).

CMS line

Genotype lR58025 A lR62829 A PMS10 A PMS3 A

Pollen Spikelet Cate- Pollen Spikelet Cate- Pollen Spikelet Cate- fertility (%) fertility (%) gory d fertility (%) fertility (%) gory fertility (%) fertility (%) gory fertility (%) fertility (%) gory

Pollen Spikelet Cate-

R b Kh c Kh R Kh Kh R Kh Kh R Kh Kh

Basmati 385 43.90 71.53 82.91 R e

Chandan 87.40 87.95 81.62 R P1031-8-5- 2.00 6.00 10.43 WM

1-1

IET-12020

Khalsa 7 - 71.60 63.40 PR

HKR241- 86.95 68.80 80.34 R

S.A.F.

Karnal Local 92.47 73.87 81.15 R HKR46 83.80 70.17 78.82 R 59.90 P1173-2-1 72.60 43.62 4.83 PR P1173-4-1 08.00 0.00 0.87 M P615-K-167-

13 27.20 0.00 3.71 WM Hasan Sarai 55.00 45.00 49.08 PR Basmati 370 - 0.00 0.00 M Pusa Basmati 10.00 0.00 0.00 M

64.42 66.47 91.00

38.70

87.24 74.13 72.40 80.57

0.00

0.02 71.19 0.00 0.00

69.07 69.90 80.55

69.02

60.21 69.70 60.08 65.67 5.25

1.63 49.17 0.00 0.00

PR 53.50 76.56 81.10 R 85.40 71.51 82.43 R PR 37.80 60.25 79.17 R 90.25 81.00 80.14 R R 52.00 82.84 79.96 R 61.70 92.80 78.85 R

PR 71.20 64.50 80.29 R 63.15 60.00 80.60 R

PR 84.69 77.60 80.05 R 82.70 78.51 64.52 PR PR 67.80 79.40 79.10 R 90.70 74.00 45.71 PR PR 83.15 81.09 86.35 R 85.30 84.04 66.85 PR PR 81.05 61.00 53.82 PR 77.30 40.25 58.97 PR WM 0.00 0.00 0.47 M 09.00 0.00 0.67 M

WM - 0.00 0.00 M 23.30 1.00 0.00 M PR 43.70 63.50 26.90 PR 37.50 58.82 45.30 PR M - 0.00 0.00 M 0.00 0.00 M M 0.00 0.00 0.00 M 0.00 0.00 0.00 M

a Data pooled over 2 replications. b R = 1993 rabi (wet season). c Kh = 1993 kharif (dry season). d R = restorer, PR = partial restorer, WM =weak maintainer, M = maintainer. e – = Crops not attempted because of nonsynchronization.

IRRN 19:4 (December 1994) 5

Breeding methods

-

Table 2. Grain quality features of promising Basmati restorers and maintainers. a

Genotype Aroma b Before cooking After cooking

Grain Grain L-B Grain Grain L-B Elongation Alkali length breadth ratio length breadth ratio ratio value (mm) (mm) (mm) (mm)

Basmati 385 1 6.6 1.7 3.9 11.9 2.7 4.4 1.8 4.0 Chandan 1 7.3 1.8 4.1 12.4 3.5 3.5 1.7 4.0

1 8.2 1.8 4.6 16.4 2.5 6.6 2.0 5.0

S.A.F. Khalsa 7 4.0

1 7.4 1.8 4.1 15.6 2.6 6.0 2.1 4.0 Karnal Local 1 7.3 1.7 4.3 13.9 3.6 3.9 1.9 HKR46

4.0 6.0

1 5.5 1.7 3.2 8.3 2.4 3.5 1.5 1.0 2 5.5 1.7 3.2 8.8 2.8 3.1 1.6 1.0

Hasan Sarai 2 0.7 1.8 4.5 12.1 1.9 6.4 1.8 7.0

Basmati 370 1 6.9 1.8 3.8 12.4 2.1 5.9 1.8 4.0 4.0

Pusa Basmati 1 2 7.2 1.8 4.0 14.4 2.2 6.5 2.0 6.0

P1031-8-5-1-1 HKR241-IET-12020 1 7.5 1.7 4.4 12.8 3.0 4.3 1.7

2 5.5 1.7 3.2 8.3 1.9 4.4 1.5 P1173-2-1 P1173-4-1 P615-K-167-13 2 6.4 1.7 3.8 12.2 2.5 4.9 1.9

a Data pooled over 2 replications. b 1 = strong; 2 = moderate.

Basmati 385. Chandan, and HKR241- IET- 12020 were found to be effective

A, and S.A.F. Khalsa 7 for PMS10 A

A, PMS10 A, and PMS3 A; and P615-K- and HKR46 for lR58025 A and PMS10 four CMS lines; P1173-4-1 for IR58025 PMS10 A, and PMS3 A; Kamal Local found to be effective maintainers for the PMS3 A; P1031-8-5-1-1 for IR62829 A,

Basmati 370 and Pusa Basmati 1 were restorers for IR58025 A, PMS10 A, and (Table 1).

167-13 for PMS10 A and PMS3 A. The performance of the restorers

varied with CMS line, location, and season of testing. The differential ability to restore fertility in the CMS lines, which all have the wild abortive (WA) cytosterile system, could be because of the influence of the different nuclear backgrounds of the CMS lines.

Among the restorers, Basmati 385, Chandan, P1031-8-5-1-1, HKR241-IET- 12020, S.A.F. Khalsa 7, and Karnal Local possess acceptable grain dimensions and desirable degree of aroma and volume expansion through linear kernel elongation (Table 2). Similarly, among the maintainers, P615-K-167-13, Pusa Basmati 1, and Basmati 370 have acceptable grain and cooking quality characteristics for Basmati rice. These genotypes will contribute to developing Basmati hybrids and provide restorers and maintainers with acceptable key Basmati quality characteristics.

Identifying maintainers and restorers for three cytoplasmic male sterile lines of rice Yog Raj and M. P. Pandey, Plant Breeding and Genetics Department, G.B. Pant University of Agriculture and Technology (GBPUAT), Pantnagar 263145; and A. Kumar, Genetics Division, Indian Agricultural Research lnstitute, New Delhi 110012, India

In hybrid rice breeding programs based on a cytoplasmic genetic male sterility system, identifying effective maintainers and restorers is important.

lines (CMS) V20 A, Zhen Shan 97 A (ZS97 A), and IR46830 A, which all possess wild abortive (WA) cytoplasm, with 18 varieties and elite lines in a line × tester design at the Crop Research Centre, (CRC), GPUAT. The 54 hybrids and their parents were transplanted in two 3-m rows at 20- × 20-cm spacing during 1991 wet season (WS).

Five plants were randomly selected and used for analyzing pollen and spikelet fertility. About 10 spikelets, representing the upper, middle, and lower portions of half emerging panicles, were collected and squashed in 2.2% IKI stain to observe pollen fertility.

We crossed cytoplasmic male sterile

Fertility reaction a of F 1 hybrids involving 3 CMS lines at CRC, Pantnagar, India. 1991 WS.

CMS line

V20 A ZS97 A lR46830 A Variety/elite line

Narendra 118 PR PR PR Kasturi M PM M UPR79-11 R PR R N22 M PR PR Rasi PR R PM Govind R R IR36 R R PR

PR

UPR79-123 R R R BG367-4 PM PM R Pant Dhan 4 M PR PM Sarju 52 R PR PM Pusa 205 PR PR R Suweon 294 R PR R Suweon 325 R R R Manhar R R PM Pusa 702 R R PM Suweon 332 R R R UPR231-28-1-2 R PR PR

a R = restorer (60.100% pollen fertility, 80-100% spikelet fertility), PR = partial restorer (30.60% pollen fertility, 30.80% spikelet fertility), PM = partial maintainer (1.30% pollen and spikelet fertility), and M = maintainer (<1% pollen and spikelet fertility).

Restorers and maintainers identified and Pusa 702 for ZS 97 A; and UPR79-11, were usually different for the three CMS

hybrid rice breeding program. for V20 A: Rasi, Govind, IR36, Manhar, promising restorers and maintainers in o Manhar. Pusa 702, and UPR231-28- 1-2 of maintainers (7.4%). We are using the 11, Govind, IR36. Sarju 52. Suweon 294, of restorers (48.1 %) was higher than that restorers found promising were UPR79- and Kasturi for IRS6830 A. The frequency fertility of all the CMS lines. Some other Kasturi. N22, and Pant Dhan 4 for V20 A 332, and UPR79-123 consistently restored IR46830 A. Maintainers identified were lines (see table). Suweon 325, Suweon BG367-4. Pusa 205, and Suweon 294 for


Influence of stigma extract on in vitro germination of pollen in Oryza species S. R. Venkatachalam and S. R. Sree Rangasamy, Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore 641003, lndia

Pollen germination and pollen tube growth were compared under in vivo and in vitro conditions in five Oryza species. We also studied the effect of stigma extract of one species on the pollen germination and pollen tube growth of other species. The experiment was replicated seven times for both in vivo and in vitro studies. Thirty stigmas per replication were used for in vivo studies and 10 cavity slides per replication were analyzed for in vitro germination. Pollen

grains were germinated in the media. M1 contained 20% sucrose (w/v) and 2 ppm boric acid, and M2 contained M1 medium, to which stigma extract was added from the respective female parent (see table). In vivo pollen germination was studied in corresponding crosses and on selfing (see table).

Pollen germination of IR64 and IR50 was not affected by adding stigma extracts of O. nivara, O. glumaepatula, and O. rufipogon. Similarly, pollen germination of O. glumaepatula and O. rufipogon was not affected by stigma extracts of IR50. Pollen germination was reduced by up to 58% in IR58025 B by O. latifolia stigma extract. Adding stigma extract of O. latifolia to the pollen of O. sativa and vice versa reduced pollen tube growth by up to 50-75%. A significant

positive correlation was obtained between in vivo pollen germination on selfing and in vitro pollen germination. A similar observation was made in in vivo pollen germination in crosses and in in vitro pollen germination (see figures a and b).

In vitro pollen germination reflects in vivo pollen germination. It appears that the stigma extract may contain a substance incompatible with a recognition substance or protein released by the pollen grain. An inhibitory effect of style and stigma extracts occurs in crosses of distantly related Oryza species. Inhibitory substances present in the stigma of unrelated species could be important in wide crosses of Oryza.

In vivo and in vitro pollen germination and pollen tube growth. a

Mean pollen germination b (%) Pollen tube growth C (microns)

In vitro In vivo In vitro In vivo Genotype

M1 medium O. sativa (IR50) 43.6 90.6 1.89 30.00

O. sativa (IR64) 45.3 93.3 2.07 31.00 (41.3) de (72.6) i

(42.1) e O. sativa (IR58025 B) (43.1) e O. glumaepatula 34.0

O. rufipogon 33.7

O. nivara 16.7

O. latifolia 7.6

(35.7) e

(35.4) a

(23.0) c

(15.8) b

(75.6) 90.9

(75.5) 87.9

(69.7) 89.4

(71.2) 72.9

(58.7) 61.8

(51.9)

j 2.03

j 1.89

i 1.94

1.93

1.76

ij

h

g

28.00 28.00

29.00

25.00

23.30

Correlation r = 0.99*d r = 0.69*

M2 medium O. glumaepatula / lR50

IR50 / O. glumaepatula

O. rufipogon / lR50

IR50 / O. rufipogon

O. nivara / lR64

IR64 / O. nivara

O. latifolia / lR580256

IR58025A / O. latifolia

42.3 (40.6) e 30.1

(33.2) b 42.7

(40.8) e 33.3

(34.7) f 44.4

(41.8) e 15.6

(23.2) c 8.1

(16.4) b 3.9

(11.3) a

50.3 1.62 (45.1) f 39.6 1.52

(39.0) e 51.6 1.53

(45.9) f 49.1 1.67

(44.5) f 30.7 1.56

(33.6) f 29.9 1.79

(33.1) c 21.0 0.50

(27.2) b 10.0 0.85

(18.3) a

16.70

6.10

17.20

15.83

15.00

12.08

6.70

4.31

Correlation r = 0.86* r = 0.68*

a Treatments having common letters are at par with each other. Numbers in parentheses are transformed values. b Pollen germination was 60 min after dusting. c Pollen tube growth 6 h after dusting in in vitro study and 24 h after dusting in a vivo study. d * = highly significant at (P = 0.05).

a. In vitro pollen germination of lR58025 B in a chemical medium containing stigma extract 20 min after dusting.

b. Pollen germination and pollen tube growth in parental crosses of IR50 / 0. glumaepatula under in vivo condition, 1 h after pollination.


Effect of temperature regime on grain chalkiness in rice C. Bangwaek, B. S. Vergara, and R. P. Robles, IRRI

Grain quality determines the market price of rice. High-yielding varieties with low grain quality are not well accepted by farmers and consumers.

Chalkiness is an important grain quality characteristic because it causes broken grains and nonuniformity of the physical appearance of grains. Chalkiness varies even in the same variety and location. It may be possible that the factors affecting the accumulation of photosynthate during spikelet filling also affect the compactness of starch granules, causing chalkiness.

Temperature affects almost all proc- esses in plants, and chalkiness is probably

not an exception. We studied the effect of temperature regime on chalkiness in rice grains.

Seeds of three cultivars (LMN111, PG56, and HTA60) were sown in Aug 1992 in pots with puddled Maahas clay soil mixed with 3 g of ammonium sulfate. Three seeds were sown per pot but only one plant per pot was left to grow. One month after emergence, the plants were subjected to a 10-h photoperiod to induce flowering. At flowering, they were placed in temperature-controlled growth chambers, with natural light and 80% relative humidity until maturity. The day/night temperature regimes used were: 22/15, 25/15, 30/20, and 35/20 °C. After harvest, rice grains were dehulled and scored for chalkiness using the procedure of the Rice Grain Quality Laboratory, Rice Research Institute. Thailand: 0 = no chalkiness, 1 = less than 10% chalky area, 2 = 10-20%, 3 = 20-50%, 4 = 50- 75%, and 5 = above 75%.

1. Percentage of filled spikelets of HTA60, LMN111, and PG56 at different temperature regimes.

2. Chalkiness score of deepwater rice (HTA60) and floating rices (LMN111 and PG56) subjected to various temperature regimes in growth chambers. IRRI, Los Baños, Philippines. Oct 1993-Jan 1994.


The experiment was laid out in a randomized complete block design with three replications.

The high temperature regime (35/ 20 °C) had the most adverse effect on percentage of filled spikelets in all cultivars tested. At low temperatures (22/ 15 °C), HTA60 was the least sensitive while LMN111 and PG56 had compara- ble high sensitivity. The 30/20 °C temperature regime resulted in a higher percentage of filled spikelets for the three cultivars tested; HTA60 was the least sensitive to temperature regime (Fig. 1).

Optimum temperatures for low chalkiness were 25/15 °C and 30/20 °C (Fig. 2). Low temperature (22/15 °C) increased chalkiness but not as serious as did high temperature (35/20 °C), although low temperature affected panicle exsertion and percentage of fertile spikelets. Despite low number of spikelets to fill, high temperature resulted in poor spikelet filling, although leaves were still green.

Temperature affected chalkiness. Under field conditions, temperature cannot be controlled, so the best way to reduce chalkiness is to select cultivars that are less sensitive to temperature, such as PG56.

Scented rice in Jiangxi Province, China Yu Chuanyuang and Gan Shuzhen, Rice Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China

Gan-xian-da-he-zi, Gi-shui-xiang-nu, Gi- an-xiang-he-zi, and Long-nan-xiang-he are traditional local scented rice cultivars in Jiangxi Province. All three of these are unsuitable for cultivation because of their tall stature, low yield potential, and poor grain appearance, which does not meet the demands of the modern rice market.

We started to work on breeding new scented rices in 1985. Many aromatic rices, including IR841, Basmati 370, and Khao Dawk Mali 105, were selected for use in the crossing program. We followed the objective of breeding semidwarf, high quality rice with slender grain and at least 5% higher yield than

Grain quality

Shuang-zhu-zhan, a high quality rice variety planted widely in southern China.

Two semidwarf indica scented rice varieties were produced. Gan-wan-xian 22 was released for commercial production in Mar 1994 by the Seed Board of Jiangxi Province. It is the first modem scented variety in Jiangxi Province.

Gan-wan-xian 22 was derived from the cross IR841/84-06, a strain from the cross of IR24/Gui-chao. The selected strain SR4044 has aromatic grain, good grain appearance, intermediate amylose content (AC) and gelatinization temperature (GC), soft gel consistency (GC), and promising agronomic characteristics (see table). It yielded 5.3 t/ha in regional trials for the late rice crop in the double- cropped system in 1992-93 and was not significantly different from the high- yielding check M112. It yielded 15% more than Shuang-zhu-zhan. Its average yield was 4.5-6.8 t/ha. In Oct 1992, Jiangxi-xiang-si-miao rice, a commercial product of Gan-wan-xian 22, won a bronze prize at the First China Agricul- ture Exposition.

SR5041, another preferred scented rice variety was also put into production. It is from the cross of IR841/Zao-xiang 17, has a heavy fragrance, low AC value, low GT, and soft GC (see table). The average yield was about 4.1 t/ha, which

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Quality characteristics of Gan-wan-xian 22, SR5041, and Shuang-zhu-zhan. a

Characteristic Gan-wan-xian 22 SR5041 Shuang-zhu-zhan

Milling quality Brown rice (%) Milled rice recovery (%) Head rice (%)

79.6 70.1 60.1

Grain appearance 1,000-grain whole Milled rice weight (g) 18.4 Kernel length (mm) 6.9 L-W ratio 3.3 Chalky kernels (%) 14.0 Area with chalkiness (%) 1.9

80.1 70.5 61.5

20.2 7.2 3.4 9.0 1.5

Chemical characteristics AC value (%) 20.1 Alkali spreading value 4.1 GC value (mm) 83.0 Protein content of milled rice (%) 6.5

Eating quality Cooked rice elongation 1.6 Aroma Medium Taste Good

16.1 7.0

66.0 7.1

1.7 Strong

Very good

76.4 71.1 67.8

12.1

2.9 9.0 1.3

5.8

26.6 6.0

29.0 6.7

1.2 None Good

a Samples were from late rice crop in the double-cropped system, late 1992.

was 10% more than that of Shuang-zhu- zhan.

Gan-wan-xian 22 has good resistance to blast and brown planthopper. It was cultivated as a late rice variety in Jiangxi Province in 1993 on about 10,000 ha.

SR5041, also a late rice, has a growth duration that is 10 d shorter than that of Gan-wan-xian 22, which is similar to that of Shuang-zhu-zhan. Both scented rices are very popular in the local markets and are being exported to Southeast Asia.

Stability of rice grain quality levels (0 and 30 kg/ha) were combined

under different fertilizer levels machine (model THU-35A) and McGill

into 12 fertilizer levels. Rice was dehulled using a Satake rice husking

Nguyen Duy Bay, Cuu Long Delta Rice Research Institute, Omon, Cantho, Vietnam

We conducted this experiment to study how the levels of fertilizer affect the stability of rice grain quality. Six varieties were grown in the 1993 wet season in a stability model where three N levels (0, 40, and 80 kg/ha), two P levels (0 and 40 kg/ha), and two K

polisher no. 3. The percentages of brown rice, white

rice, and broken rice in all varieties were unstable under different fertilizer levels, with S 2 di significant from zero (Table 1). The responses of milling quality to fertilizer levels did not follow the linear model, suggesting that milling quality was affected by many other factors in addition to fertilizer levels.

Table 1. Stability parameters for milling quality of some varieties.

Brown rice(%) Variety

X bi S2 di

OM987-1 77.8 0.77 0.65 lR58082 76.8 3.63 5.19 MTL 105 78.5 –0.04 0.14 OM269 78.8 0.49 5.49 lR53964-39 77.9 0.91 0.76 IR29723 78.3 0.21 0.35

White rice (%)

X bi S2 di

68.2 0.73 2.09 66.8 2.36 9.46

69.6 0.69 5.68 68.3 0.87 2.69 68.8 1.16 2.09

70.0 0.28 0.56

Broken rice (%)

X bi S2 di

36.1 0.27 35.34 33.8 0.17 16.10 21.5 2.92 54.14 30.4 1.59 66.80 23.3 1.43 40.67 23.0 0.17 30.63


Table 2. Stability parameters for grain dimensions and chemical properties of some varieties.

Grain length (mm) Length-width ratio Chalkiness (%) Variety

X bi S 2 di X bi S 2 di X bi S 2 di

0M987-1 8.7 2.55 0.040 3.16 1.23 0.010 5 0.50 lR58082 7.8 0.15 0.050 3.01 0.83 0.007 5 1.35 0.20

0.30

MTL 105 7.7 OM269

0.51 0.001 2.66 1.76 0.010 1 1.06 0.08 8.5 1.17 0.040 3.41 0.70 0.005 1 0.62 0.05

lR53964-39 8.0 1.22 –0.0006 2.72 0.79 0.002 5 1.17 0.01 lR29723 8.0 0.46 –0.0006 2.88 0.68 0.016 5 1.39 0.40

Amylose content (%)

X bi S 2 di

23.9 1.33 2.07 24.3 0.54 4.41 26.3 0.90 2.75 26.4 1.43 2.45 28.3 0.71 3.58 28 1.18 3.45

Physical dimensions as well as chalkiness were very stable (Table 2), and responses of these varieties followed the linear model. For amylose content, however, responses were quite complex and considered unstable under different fertilizer levels.

Inheritance of resistance to rice tungro spherical virus in some rice cultivars L. A. Ebron and R. R. Yumol, IRRI; R. Ikeda, IRRI and Laboratory of Rice Breeding Methodology, National Agriculture Center (NARC), Kanondal, Tsukuba, lbaraki 305, Japan; and T. Imbe, IRRI

Many rice cultivars serve as sources of resistance to rice tungro spherical virus (RTSV). RTSV resistance could be an important factor in controlling tungro disease because the vector, green leafhopper (GLH) Nephotettix virescens, can transmit the rice tungro bacilliform virus (RTBV) only when it has previ-

The results indicated that milling quality and amylose content were unstable under different fertilizer dosages while grain dimensions and chalkiness were stable.

Reactions to RTSV of F 1 and F 3 progenies from crosses of 3 resistant rice cultivars with TN1 and crosses between resistant parents.

F 3 lines Cultivar/cross Reaction a

Resistant Segregating Susceptible Fit P

Utri Merah Utri Rajapan Pankhari 203 Taichung Native 1 Utri Merah/TN1 (F 1 ) TN1/Utri

Pankhari 203/ Rajapan (F 1 )

TN1 (F 1 ) Utri Rajapan/

Utri Merah (F 1 ) Utri Rajapan/

Pankhari 203 (F 1 )

R R R S S S

M R R

R

62 66 13 21 65 b

41 71 40

118 0 0

167 0 0

7:8:1 2.279 0.25-0.50 1:3 0.010 0.90-0.95

1:2:1 0.671 0.70-0.8

a R = resistant, M = moderately resistant, S = susceptible. b Pooled segregating and susceptible reactions.

ously acquired RTSV. However, the genetics of resistance to RTSV infection in these cultivars is not fully understood.

Histogram of the infection rates with RTSV in the Utri Merah/TN1 F 3 lines.

We undertook this study to efficiently breed cultivars resistant to RTSV.

Utri Merah (IRGC Acc. 16680), Utri Rajapan (Acc. 16684), and Pankhari 203 (Acc. 5999). The F 1 and F 3 progenies of crosses between resistant cultivars and Taichung Native 1 (TN1), a RTSV- susceptible cultivar, were tested to determine the mode of inheritance for resistance to RTSV infection. We also determined the allelic relationships of the resistance genes among the resistant cultivars.

Thirty seedlings in each F 3 line were tested for RTSV, except for the F 3 lines of Utri Merah/TN1, for which 60 seedlings were inoculated per line.

In the artificial inoculation, five 10-d- old seedlings were grown in a clay pot

We studied RTSV-resistant cultivars


Pest resistance— diseases

- - -

- - -

- - - -

- - - -

- - - -

- - - -

- - - -

- - - -

c 2

and confined in a mylar cage for 4 h with 10 viruliferous GLH adults per seedling. The GLH adults were given 3 d of access on TN1 plants doubly infected with RTBV and RTSV to acquire both viruses prior to inoculation. We took 5-cm-long strips of the 2d and 3d youngest leaves of each seedling 2-3 wk after inoculation to detect RTSV by ELISA.

In Utri Merah/TN1, the F 3 progenies segregated into 62 resistant plants (RTSV infection was 0-20%), 66 segregating (21 -75%). and 13 susceptible (76- 100%) (see table), resulting in a good fit to a 7:8:1 ratio (see figure). The F 1 plants of Utri Merah/TN1 were susceptible to RTSV infection, clearly indicating that

Gall midge biotype 5 identified in Moncompu, Kerala, India K. P. V. Nair and D. Ambika Devi, Rice Research Station, Moncompu, Kerala, India

Four biotypes (1 -4) of the Asian rice gall midge ( Orseolia oryzae ) (Wood- Mason) from different rice-growing areas of India have been identified and evaluated. Many gall midge-resistant rice donors and cultures were susceptible at Moncompu, a gall midge-endemic area.

We evaluated 10 differentials in three major groups and susceptible check Taichung Native 1 (TN1), all with known reactions to the biotypes, during 1991-92 wet seasons. The entries were transplanted in early June and late June to allow for peak gall midge infestation. Thirty-day-old seedlings were transplanted in 3-m rows for each variety at 15- × 15-cm spacing. Percentage of plant and tiller damage was recorded at 50 d after transplanting (DAT).

Potential donors Eswarakora (group 1) and Siam 29 (group 2) showed little damage while Velluthacheera (group 3) exhibited more damage. Up to 85% plant damage was recorded in TN1 see tab1e).

Utri Merah has two recessive genes for resistance to RTSV.

The F 3 analysis in TN1/Utri Rajapan gave a segregation ratio of 1:3 and that in Pankhari 203/TN1 a 1:2:1 ratio, indicating monogenic control of resistance in both Utri Rajapan and Pankhari 203. The F 1 plants of the TN1/Utri Rajapan were susceptible to RTSV while those of Pankhari 203/TN1 showed an intermediate infection rate.

The allelism test between Utri Merah and Utri Rajapan revealed no segregation of F 3 progenies for susceptibility. The F 1 plants were resistant to RTSV infection. This suggests that the recessive gene in Utri Rajapan is the same as one of the two recessive genes in Utri Merah.

The F 3 lines of Utri Rajapan/Pankhari 203 also showed no segregation for susceptibility to RTSV infection and the F 1 plants were likewise resistant, suggesting the presence of the same gene that controls RTSV resistance in Pankhari 203. The inconsistency of dominance of both cultivars could be explained by a dominant GLH resistance gene in Pankhari 203, Glh- 1, which might suppress RTSV infection.

From these findings, we propose two gene symbols: tsv- 1, for a gene for RTSV resistance that is common in the three cultivars, and tsv -2, for the other gene in Utri Merah that may be used in breeding programs to diversify gene sources for RTSV resistance.

Reaction of promising cultivars to gall midge biotype 5. Moncompu, Kerala, India. 1991-92 wet seasons.

Mean infestation for two seasons Group Entry Differential

Damaged plants (%) Silvershoots (%)

1 W1263 5.0 4.0 I 2 ARC6605 27.5 5.2 II 3 Phalguna 2.5 3.6

4 ARC5984 2.6 4.6

5 CR-MR1523 40.4 12.3 6 Velluthacheera 37.5 10.9

III 7 Aganni 40.0 22.9 8 Ptb10 37.5 12.8 9 T1477 43.1 22.1

IV 10 TN1 85.0 29.5

Gall midge populations at Moncompu, biotype 5, with the characteristic R-R-S-S Kerala, tend to be distinctly different

earlier. They have been designated as tials. from the four biotypes characterized pattern for the four groups of differen-

Inheritance of whitebacked planthopper resistance Le Thi Sen, University of Cantho, Cantho, Omon, Vietnam

We studied the mode of inheritance for resistance to the whitebacked planthopper (WBPH) Sogatella furcifera (Horvath) in six resistant local cultivars of rice in the Mekong Delta of Vietnam.

Seedlings at the one-leaf stage were artificially infested with second- and third-instar WBPH nymphs. Reactions of the seedlings were recorded when the susceptible check, Taichung Native 1

(TN1), was completely killed. Seedlings were scored as resistant when they showed reactions similar to those of the resistant check, and as susceptible when they were completely killed or severely stunted with signs of wilting. The reactions of F 1 and F 3 lines were scored on a row basis, while F 2 populations were scored on an individual seedling basis. For the F 3 lines, rows were scored as homozygous resistant, segregating, or homozygous susceptible.

The F 1 seedlings in all crosses were resistant, indicating that resistance was dominant in all six cultivars. The F 2


Pest resistance— insects

Gall midge incidence is a constraint that limits rice production in some areas. We undertook a program to develop high- yielding gall midge-resistant rice gena- types that mature late.

Cultivar Ratnagiri 3 was bred from the cross CR57-MR-1523/IOR 36//RTN 68. Maharashtra State released it for general cultivation in 1994. It is a semitall, long-duration variety (142 d) with long, bold grains.

In station trials from 1984 to 1986, Ratnagiri 3 outyielded the check variety in gall midge-endemic areas. In multilocation trials from 1987 to 1989, and

D. S. Sawant, S. A. Chavan, B. M. Jamdgni, and B. B. Jadhav, Agricultural Research Station, Shirgaon 415629, Maharashtra, India

In the cross TNl/IR2035-117-3, the F 2 populations segregated in the ratio of 15 resistant to 1 susceptible, indicating that two dominant genes governed resistance. The F 2 populations of the crosses of TN1/ BR46 and TN1/Xoai Cat segregated in

populations from the crosses of TN1 with Base, Rong Lem, Keo Cha A, and La segregated in the ratio of 3 resistant to 1 susceptible, indicating that a single dominant gene confers resistance (Table 1).

Table 1. Reaction to whitebacked planthopper of F 1 and F 2 populations from crosses of rice cultivars with TN1. University of Cantho, Vietnam, 1993.

F 2 seedlings P Cross

reaction Total Resistant Susceptible 3:1 15:1 13:3 3:1 15:1 13:3 F 1

(no.) (no.) (no.) (%)

TN1/lR2035-117-3 R 1379 1292 87 6 256.94 0.008 140.11 <0.01 90-95 <0.01 TN1/BR46 R 1471 1196 275 18 31.19 388.81 0.003 <0.01 <0.01 90-95 TN1/Xoai Cat R 1468 1193 275 18 30.75 390.40 0.0003 <0.01 <0.01 95-99 TN1/Base R 1221 912 309 25 0.06 756.79 34.46 80-90 <0.01 <0.01 TN1/Keo Cha A R 1220 910 310 25 0.11 764.35 35.52 80-69 <0.01 <0.01 TN1/Rong Lem R 1351 1005 346 25 0.27 864.26 41.74 60-70 <0.01 <0.01 TN1/La R 1227 915 312 23 0.12 770.18 35.92 70-75 <0.01 <0.01

Table 2. Reaction to whitebacked planthopper of F 3 lines from crosses of rice cultivars with TN1. University of Cantho, Vietnam, 1993.

F 3 lines (no.) P Cross

Total Resistant Segregating Susceptible 1:2:1 7:8:1 1:2:1 7:8:1

TN1/lR2035-117-3 335 147 167 21 94.79 0.003 <0.01 >99 TN1/BR46 334 150 162 22 98.41 0.31 <0.01 80-90 TN1/Xoai Cat 328 147 159 22 95.58 0.35 <0.01 80-90 TB1/Base 372 97 185 90 0.27 218.21 80-90 <0.01 TN1/Keo Cha A 374 95 181 98 0.43 267.22 75-85 <0.01 TN1/Rong Lem 363 90 177 96 0.42 266.83 75-85 <0.01 TN1/La 350 89 180 81 0.65 186.80 65-75 <0.01

the ratio of 13:3, suggesting that resistance in the two varieties was governed by one dominant and one recessive gene.

The results from the F 3 progenies confirmed the conclusion drawn from the F 2 data (Table 2). In all crosses, except TN1 /Xoai Cat, TN1 /BR46, and TN1/IR2035-117-3, the observed data agreed with the 1:2:1 resistant, segregating, susceptible ratio expected for monogenic control of resistance. The F 3 data from crosses of TN1/IR2035-117-3, TN1/BR46, and TN1/Xoai Cat agreed with the 7:8:1 ratio expected for digenic control of resistance.

Ratnagiri 3: a new gall midge-resistant, late- maturing variety from Maharashtra, India

Table 1. Grain yield of Ratnagiri 3. Maharashtra, India. 198492.

Grain yield (t/ha)

Ratnagiri 3 Check a

(RTN121) variety

Trial

Station trials, 1984-86 wet season 4.1 3.1 Multilocation trials, 1987-89 wet season (8 locations) 4.4 3.9 All India Coordinated Yield Trial 4.2 3.7 MRVT b 4 1988 wet season (12 locations) Field trial 1990-92 (34 locations) 4.4 3.5

a Vikram for station trials, Ratnagiri 68 for multilocation trials, Pankaj for MRVT 4, and Vidram for field trials. b MRVT = multiresistant variety trial.

Table 2. Ratnagiri 3 reactions to pests and diseases in multiresistant variety trial 4, 12 locations, a

1988 wet season.

Reaction b

Variety Disease Insect pest

Blast Bacterial Sheath Brown Gall midge 1 Gall midge 4 Stem borer leaf blight blight spot

Ratnagiri 3 R MR MR MR R R MR Pankaj MR S MR S S S MR

a Locations had high disease or insect pest pressure. b R = resistant, MR = moderately resistant, S = susceptible.


c 2

c 2

field trials from 1990 to 1992, it outyielded the check variety (Table 1). In the All India Coordinated Yield Trials, it

ranked 7th out of 81 entries during 1988. Ratnagiri 3 has resistance to gall midge

biotypes I and IV and blast disease and

moderate resistance to stem borer, bacterial leaf blight, sheath blight, and brown spot (Table 2).

Peiliangyou Teqing, a new high-yielding, two-line hybrid rice Liao Fuming, Hunan Hybrid Rice Research Center (HHRRC), Changsha 410125 Hunan, China

Peiliangyou Teqing (Pei’ai 64S/Teqing), developed by HHRRC, passed the examination of the Crop Variety Release Committee of Hunan Province in Jan 1994. It is the first two-line hybrid rice combination approved at the

provincial level for release to farmers in China.

Pei’ai 64S, the maternal parent, is a thermosensitive genic male sterile line bred from Nongken 58S/Pei’ai 64//Pei’ai 64. It shows pollen sterility of 99.98% and seed sterility of 100% based on a 50- panicle sample of 1,150 plants in 1990. It has a long sterile period: about 20 d at Shengyang, Beijing, and Guiyang; more than 50 d at Changsha; and nearly 80 d at Guangzhou—and even longer at Hainan.

Gan wan Xian 23 (Gan You Wan, SG89320): a new indica rice variety with high quality Cao Fengsheng and Zhang Bake, Research Division, Application of Atomic Energy and Agro-Information Institute, Jiangxi Acad- emy of Agricultural Sciences, Nanchang 330200, China

Gan wan Xian 23, released in May 1994 by the Jiangxi Provincial Seed Board, is a new semidwarf indica rice variety with high quality and other good traits. It was derived from the cross between IR841 and M79215, which is a strain from the cross Xi Dao 1/5450. The F 3 was irradiated with 60 Co g -rays at the dose of 30 krad.

Gan wan Xian 23 is suitable for the later season in the double-cropped area of southern China and single-cropped area of central China. Because of its high quality, it won the gold medal prize at the First China Agriculture Exposi- tion, sponsored by the Ministry of Agriculture in Oct 1992. In the double- cropped area, its average yield was 4.9- 5.3 t/ha, which was 15% more than that of Shung Zhu Zheng, a check being used for the new high-quality evaluation in southern China. In the single-cropped area, the average yield of Gan wan Xian 23 was 5.3-6 t/ha.

The variety has strong stems, is 92- 105 cm tall, and has a growth duration of 135-140 d. Gan wan Xian 23 has high yield potential under good irrigation and management conditions. It performed Major quality traits of Gan wan Xian 23. Rice Research Institute of China. 1992.

Brown rice (%) 78-80.2 Milled rice recovery (%) 63-66.3 Head rice (%) 58-63 Kernel length (mm) 6.7 L-W ratio 3.3 Chalky kernel (%) 0 Area with chalkiness (%) 0 Amylose content (%) 15 Alkali spreading value 6.9 Gel consistency (mm) 90 Protein content of head rice (%) 7.0

well in regional trials, with yield reaching 6.3 t/ha in Hu Bei Province.

to blast disease. It has long, slender, translucent grains with intermediate amylose content, low gelatinization temperature, and soft gel consistency (see table). The cooked rice of Gan wan Xian 23 is soft and aromatic.

It has a 1,000 grain weight of 23-25.7 g, panicle length of 21.5-29.3 cm, and

Gan wan Xian 23 has good resistance

Heibao, a high-yielding, good quality black indica rice for China

Yan Wenchao, Qui Beiqin, Jin Qingsheng, and Luo Rubi, Crop Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China

Heibao is a newly released semidwarf indica variety with a black pericarp. It is derived from Dong-Lan-Mo-Mi/IR64 and has a 108-112 d duration. Heibao is highly cold tolerant at the seedling stage and is resistant to blast and bacterial blight. During the 1993 early season in Zhejiang, Jiangxi, Hubei, and Anhui, blast attacked many rice varieties but not Heibao. It has wide adaptability as an early rice in the double-cropped Yangtze River area.

Average yield at eight locations was 6.8 t/ha in 1993. The highest yield,

88.7-116 field grains/panicle (82.5- 91.8%). Gan wan Xian 23 is very popular among consumers in Hongkong. Its quality is at par with the high-quality Thai rices. Gan wan Xian 23 is being grown in Jiangxi, Hubei, Guangdong, Anhui, and Guanxi provinces, and is spreading quickly in other provinces of southern and central China.

9.0 t/ha, was 25-40% more than the yields of the local black rice check varieties. Heibao has a 1,000-grain weight of 21.2 g, with 90% seed fertility.

Appearance, milling recovery, chemical properties, cooking, and eating quality meet China’s national index for high quality rice. Heibao’s grain quality is superior to that of most black pericarp indica varieties in China. Grain length is 7.0 mm, with a 3.2 length-breadth ratio. Hulling recovery is 79%; milling recovery, 70.2%; and head rice recovery, 53%. Grain is semitransluscent with 19.3% amylose and 10.4% protein content. Four percent of the grain is chalky, with 0.2% area with chalkiness. It has intermediate gelatinization temperature and gel consistency (5.6 mm). Fe, P, Se, and other minerals are 3-5 times greater in Heibao than in ordinary rice.


Integrated germplasm improvement—irrigated

Table 1. Comparison of grain yield between Peiliangyou Teqing and check Shanyou 63. HRW, Hunan, China, 1992-93.

Combinations and Year Locations varieties Replications Grain yield (t/ha)

Peiliangyou Teqing over check a

(no.) (no.) (no.) Peiliangyou Teqing Shanyou 63 t/ha %

1992 7 6 3 9.5 9.1 0.43** 4.7 1993 6 9 3 7.7 7.3 0.43 ns 5.8

a ** = significant at 1% level by Duncan's SSR test; ns = not significant by Duncan's SSR test.

Table 2. Economic traits and grain quality of Peiliangyou Teqing. HRVRT, Hunan, China. 1992-93.

Days Plant Spikelets/ Filled 1,000-grain Brown Milled Head Year to height panicle spikelets weight rice rice rice Chalkiness

maturity (cm) (no.) (%) (g) (%) (%) (%) (%)

1992 136.7 97.5 140.1 87.9 23.4 79.4 69.8 45.6 5.3 1993 135.8 105.6 144.5 84.6 22.3 82.8 70.6 62.2

Mean 136.3 101.6 142.3 86.3 22.9 81.1 70.2 53.9 5.3

Pei'ai 64S has a low critical sterility demonstration plots in 1991. Planted on temperature of 23.3 °C under short

The combination was cultivated in

Hunan Province, it yielded 7.5-9.0 t/ha. ture is more than 23.3 °C, it is completely 667 ha in 1992 and 1,333 ha in 1993 in daylength. When the daily mean tempera-

The combination matures in 136 d as a medium rice crop (Table 2). It is moderately resistant to blast and bacterial blight. Peiliangyou Teqing is about 100 cm tall and has good plant type, strong tillering ability, sturdy stature, dark green leaves, and large panicles. Its seed setting rate is more than 80%, with a mean of 142 spikelets/panicle and a 1,000-grain weight of 23 g. The yields of brown, milled, and head rice were 81.1 %, 70.2%, and 53.9%, respectively. Chalkiness was 5.3% and the eating quality acceptable.

sterile; when the daily mean temperature is less than 23.3 °C, it becomes partially fertile, thus producing selfed seeds. It has also wide compatibility, and when crossed with either indica or japonica rices, it shows generally normal pollen and seed fertility in the F1 hybrids. Because Pei'ai 64s has a low critical sterility temperature (23.3 °C under short daylength), it is difficult to multiply. Yield during seed multiplication was usually unstable because of fluctuating temperatures, but more than 2.25 t/ha may be obtained by irrigating with low- temperature water.

Teqing, the paternal line, is a high- yielding indica variety developed by the Guangdong Academy of Agricultural Sciences and being grown in southern China.

In the 1992 Hunan Rice Variety Regional Trial (HRVRT) for medium rice, Peiliangyou Teqing yielded an average of 9.5 t/ha across seven locations (Table l), 4.7% (significant at 1% level) higher than the check hybrid Shanyou 63 and the best of six combinations or varieties tested. In the 1993 HRVRT, its yield averaged 7.7 t/ha across six locations, 5.8% higher than that of Shanyou 63 and the best of nine combinations or varieties tested.

Jinuo 1: a new glutinous japonica variety with high yield and good quality Liu Guoqing, Zhang Qixing, Wang Yongxin, Liu Shanzi, Rice Research lnstitute of Hebei, Tanghai 063200, China

Jinuo 1 is a new glutinous japonica rice variety derived from JG954 (58nuo/ Nonghu 6//BL-7) using the system selection method. It was released in Mar 1992 as a special rice variety.

Jinuo 1 is photoperiod-insensitive and has a 170 d growth duration. It is 100 cm tall, with panicle length of 16.5 cm, and a 1,000-grain weight of 28 g. Its fertility is more than 8.58. The yield potential of Jinuo 1 is high and stable, 0.9-32.6%

Yield potential of Jinuo 1 in the Rice Regional Trials of northern China, 1992.

Yield Increase Site (t/ha) over check a

(%)

Beijing 7.5 23.4 Zhuozhou, Hebei 9.5 32.6 Tianjin 8.0 7.32 Baoding, Hebei 10.6 31.78 Tanghai, Hebei 8.9 0.9 Liaoning 5.3 1.15

a Zhonghua 8.

more than the check in the Rice Re- gional Trials of northern China in 1992. Its yield stability was the best among the new varieties being tested (see table).

Jinuo 1 is moderately resistant to leaf blast and bacterial blight and is resistant to whitebacked planthopper. Its resistance to lodging is very strong because of its firm stems.

tics of Jinuo 1 meet China's national index for good quality rice. Hulling recovery was 84.5%: milling recovery, 76.0%; grain length, 5.1 mm; grain length-breadth ratio, 1.6; amylose content, 1.2%; and protein content, 7.4%.

It is the first time that a high-yielding glutinous japonica rice variety with good quality was selected in northern China.

Most of the grain quality characteris-

Jinuo 1 is planted on about 6,000 ha.


Routine research. Reports of screening

trials of varieties, fertilizer, cropping methods, and other routine observations using standard methodologies to establish local recommendations are not ordinarily accepted. Examples are single-season, single-trial field expe-

riments. Field trials should be repeated

across more than one season, in multiple

seasons, or in more than one location as

appropriate. All experiments should

include replications and an inter-

nationally known check or control treatment.

Nadu, India. It has become popular, however, in irrigated areas of Uttar Pradesh, West Bengal, Maharashtra, Madhya Pradesh, and Goa because of its wide adaptability, superior grain quality, and resistance to gall midge, stem borer, leaffolder, rice hispa. whitebacked planthopper, blast, sheath rot, brown spot, rice tungro virus, and sheath blight.

From 1984 to 1988, PNR381 averaged a 73.4% increase in yield over national checks Akashi, 53.8% over Cauvery, and 57.6% over Annada under direct seeded irrigated conditions. It has also outper- formed these checks under direct seeded rainfed and transplanted conditions (Table 1). The variety has shown 102% increase in yield in wet season in eastern Uttar Pradesh and 62.5% increase in yield in dry season in West Bengal over IR36 in on-farm demonstrations under irrigated transplanted conditions (Table 2). The variety is being considered for release for irrigated areas.

Table 1. Grain yield performance (t/ha) of PNR381 in coordinated trials in 1984-88 wet seasons. a

Direct Direct Variety seeded seeded Transplanted

rainfed irrigated 1984-88 1984-88 1985-88

PNR381 Akashi (check) Cauvery (check) Annada (check) -

2.2 3.8 1.8 2.2 1.9 2.5

2.4

4.1 3.8 3.6 3.5

a Pooled data from multiple Iocations.

A dual purpose rice variety: PNR381

IRRN REMINDER

S. N. Chakrabarti, Genetics Division, Indian Agricultural Research Institute, New Delhi 110012, India

PNR381 is a semidwarf, early rice variety with long slender grains, developed from the cross Tainan 3 Mutant (induced)/ Basmati 370. It was released by the Central Varietal Release Committee in 1992 for cultivation in the rainfed uplands of Andhra Pradesh and Tamil

Table 2. Duration and grain yield of PNR381 in on- farm demonstrations and station trials in Uttar Pradesh, India, under irrigated, transplanted conditions. a

1990-94.

Location Av grain yield (t/ha)

Duration (d) PNR381 IR36 Pusa 33 Saket 4 UPR-85-12 (check) NDR3006 (check) NDR3001 (check)

1990 wet season a

Beharaich (Uttar Pradesh) 117 6.4 3.2 Pusa (Bihar) 121 3.3 2.4 3.0 Varanasi (Uttar Pradesh) 105 4.2 3.9

1991-92 wet season a

Karnal (Haryana) 117 6.1 Aduthurai (Tamil Nadu) 122 4.7 3.9

Murshidabad (West Bengal) 130 8.1 5.0 1991-92 dry season a

Uttar Pradesh

Uttar Pradesh

1990-93 b

123 4.5

1993-94 b

123 4.5

4.5

4.3

4.4 4.1

4.2 3.5

a Pooled results from demonstrations conducted by universities or cooperatives. b Pooled results from 9 station trials conducted by the Government of Uttar Pradesh.


Integrated germplasm improvement—upland

- - - - - - - - -

- - - - - -

- - -

NDGR21: a new flood-tolerant Yield, maturity, and plant height of NDGR21 and check Madhukar. a Uttar Pradesh, India. 1989-93

promising line for eastern Ghaghraghat Average Farmer

Uttar Pradesh, India Variety yield field trials Plant Maturity Grain yield (t/ha) (t/ha) mean yield height (d)

P. P. Singh, J. L. Dwivedi, and R. K. Singh, Crop Research Station, Ghaghraghat, P. O. 1989 1992 1993

(t/ha) (cm) 1989-93

Jarwal Road, Uttar Pradesh, India

About two-thirds of the rainfed lowland and deepwater rice area suffers from flooding during the monsoon season every year. Short-term submergence, or and in farmers’ fieIds. NDGR21 yielded

has resistance to stem borer, neck blast, 1.7-3.0 t/ha during 1989-93 wet seasons flash flooding, in flood-prone areas sensitive and flowers in late October. It

Culm strength is intermediate. Lemma table). trait in rice grown in these areas. nonlodging, and matures in 125-150 d. NDGR21 and 1.4 t/ha for Madhukar (see gence tolerance is therefore an important NDGR21 is erect, 125-145 cm tall, Madhukar. Average yield was 2.3 t/ha for ment, resulting in poor yields. Submer- and brown spot under field conditions. compared with 0.8-1.8 t/ha for the check adversely affects initial rice establish-

tolerant traditional variety grown in centage resulting from more panicles/m2 white. and seed coat color is golden rainfed lowland and deepwater areas, is and stable performance under intermittent brown. It does not have awns. Panicles narrowing due to its susceptibility to neck flooding. NDGR21 has consistently are intermediate. L-B ratio is 2.3 and test blast. NDGR21, a selection from shown a high submergence tolerance weight is 27.5 g. Madhukar/Sena, is being developed as its score in screening trials. It can survive Yield potential is up to 3.0 t/ha under substitute. NDGR21 produced stable

areas of eastern Uttar Pradesh because of moderate ability to elongate. flood and drought periods at the early being recommended for flood-prone during the early stage and possesses yields in 1989-93 despite exposure to flash flood conditions. This variety is for 7-10 d under complete submergence

NDGR21 is weakly photoperiod- its consistent performance. seedling stage in experiment station trials

NDGR21 2.1 1.7 3.0 2.3 2.5 135 141 Madhukar 1.7 0.8 1.8 1.4 1.5 155 149

a Crops suffered from severe prolonged flooding during 1990 WS and from drought in 1991 WS at the early growth stages.

The cultivation of Madhukar, a flood- and palea are golden, grains are creamish NDGR21 has a better survival per-

Crop and resource management ~

22 kg P/kg as P 2 O 5 and 33.2 kg K/ha as K 2 O along with-half of the treatment dose of N were applied basally. The remaining

Response to nitrogen in semidwarf scented rice varieties

We conducted a field experiment

on grain yield potential and N response of at 20- × 15-cm spacing with 2-3 seed- five-day-old seedlings were transplanted influence of applying graded levels of N tillering and panicle initiation. Twenty- during 1990-92 wet seasons to study the N was applied in two equal splits at

S. P. Singh, and K. G. Pillai, Directorate of Rice Research (DRR), Rajendranagar, Hyderabad 500030, AP, India

selected rice varieties at the DRR’s

The semidwarf scented varieties in the experimental plots was clay loam were kept uniform. Ramchandrapuram Research Farm. Soil lings/hill. All other management practices

with CEC 45 meq/100 g soil. 0.1% total produced significantly higher grain yields The demand for scented rice varieties for export is growing. To exploit the grain yield potential of recently released semidwarf scented rice varieties, it is necessary to determine their response to added N and their grain yield performance at moderate and high levels of applied N. These varieties are more responsive to N compared with traditional scented varieties, the N response of which is limited to 40-50 kg/ha.

N (modified Kjeldahl method), 10 ppm of available P (Olsen’s), and pH 8.2.

Three semidwarf scented rice varieties (Haryana Basmati 1, Pusa Basmati 1, and Kasturi) were compared with check variety (Basmati 370) at five graded levels of N: 0, 30, 60, 90, and 120 kg/ha. The experiment was laid out in a split- plot design, keeping varieties in main plots and N levels as subplot treatments with four replicates. A uniform dose of

than did Basmati 370 (see table). Grain yield of Haryana Basmati 1 was significantly higher than that of Pusa Basmati 1 and Kasturi but both these varieties were at par with each other during 1990 and 1991. The 3-yr mean indicated an increase in grain yield of 45.0% with Haryana Basmati 1, 41.0% with Pusa Basmati 1, and 45.0% with Kasturi compared with that of Basmati 370.


Integrated germplasm improvement —flood-prone

Fertilizer management—inorganic sources

Incremental doses of N increased grain yield significantly up to 90 kg N/ha, after which it declined. The response to N during the second and third years was low because of stem borer damage, especially in high N treatments. Despite

these variations, the mean grain yield responses to N averaged over different varieties at 30, 60, 90, and 120 kg N/ha were 22.8, 18.4, 16.8, and 10.0 kg grain/ kg N. respectively. The mean grain yield response to NPK at 30, 60, 90, and 120

kg N/ha irrespective of variety used averaged 5.7, 7.4, 8.4, and 5.6 kg grain/ kg NPK, respectively.

The three semidwarf scented rice varieties recorded positive grain yield response to N up to 90 kg N/ha.

Effect of methods of Sesbania aculeata incorporation and nitrogen levels on lowland rice yield R. Loganathan and S. P. Palaniappan, Agronomy Department, Tamil Nadu Agricultural University, Coimbatore 641003, Tamil Nadu. India

We studied the effect of different methods of in situ incorporation of green manure S. aculeata and three N levels on rice yields in two successive field trials, Sep 1992-Jan 1993 and Jun-Sep 1993. Rice cultivars used were ADT38 (13.5 d) and IR50 (10.5 d).

Soil of the experimental field in the first season was clay loam with pH 7.9,

EC 0.5 dS/m, 0.69% organic C, and 205 kg available N/ha, 8 kg available P/ha, and 411 kg available K/ha. Soil in the second season was clay loam with pH 7.8, EC 0.5 dS/m, 0.63% organic C, and 238 kg available N/ha, 7.3 kg available P/ ha, and 37.5 kg available K/ha.

Different methods of in situ green manure incorporation at 45 d of growth were tested. Nitrogen contributed through green manure was 47.3 kg/ka in the first

Grain yield response to N (kg grain/kg N) in semidwarf scented rice varieties. DRR, Hyderabad, India. 1990-92 WS.

Grain yield (t/ha) N response (kg grain/kg N) Nutrient response (kg grain/kg NPK) Treatment

1990 1991 1992 Mean 1990 1991 1992 Mean 1990 1991 1992 Mean

Variety Haryana Basmati 1 3.3 3.1 3.2 3.2 Pusa Basmati 1 3.1 3.0 3.2 3.1 Kasturi 3.0 3.0 3.0 3.5 3.2 Basmati 370 2.4 1.9 2.4 2.2 CD (0.05) 0.2 0.1 0.5

N level (kg N/ha) 0 1.9 1.9 2.3 2.0

30 2.8 2.7 2.7 2.7 29.7 24.7 14.0 22.8 7.4 6.3 3.6 5.7 60 3.1 3.0 3.2 3.1 21.0 18.3 16.0 18.4 8.4 7.3 6.4 7.4 90 3.5 3.1 4.0 3.5 17.7 13.8 18.9 16.8 8.8 6.9 9.4 8.4

120 3.3 3.0 3.3 3.2 11.8 9.4 8.8 10.0 6.6 5.3 5.0 5.6 CD (0.05) 0.2 0.1 0.3

Effects of methods of S. aculeata incorporation in situ and N levels on rice yield. a 1992-93.

Panicles/m 2 (no.) Filled grains/panicle (no.) Treatment

Grain yield (t/ha) Straw yield (t/ha)

Season 1 Season 2 Season 1 Season 2 Season 1 Season 2 Season 1 Season 2

Main plot Incorporation method Sickle cutting + 274 510 89.2 68.2 4.5 4.6 5.8 5.9

Animal-drawn 246 516 85.3 68.6 4.2 4.6 5.4 6.0

Power tiller-operated 264 555 88.4 70.4 5.44 5.1 5.7 6.6

Tractor-drawn 305 561 90.4 70.8 5.2 5.3 6.7 7.0

LSD (0.05) 5 8 0.5 0.5 0.2 0.3 0.2 0.2

country plow

Burmese setoon

cagewheel

cagewheel

(N level (kg/ha) Subplot

0 249 509 3.5 3.9 4.6 84.6 64.9 88.3

5.1 70.2 4.8 6.1 6.4 5.0

92.0 73.5 5.5 5.9 7.0 2 0.4 0.4 0.2 0.1 0.2 0.2

7.6 50 275

100 293 LSD (0.05) 2

541 557

a Interactions were not significant.


Fertilizer management—organic sources

-

- - - - - - - -

season and 61.2 kg/ha in the second season. In both seasons, 100-50-50 kg NPK/ha were applied to rice as urea, single superphosphate, and muriate of potash. The experiments were laid out in a split-plot design with four replications (see table).

Method of incorporation significantly influenced yield attributes and grain and

straw yields. Tractor-drawn cagewheel incorporation positively influenced rice productivity compared with the other methods (see table). This influence may be because of deeper incorporation (12.5 cm in the first season and 16.7 cm in the second season), which reduced consider- ably the loss of N and increased N availability to rice, resulting in higher yields.

Grain yield increased by 0.76 t/ha with tractor-drawn cagewheel incorporation and 0.30 t/ha with power tiller incorporation over animal-drawn implement incorporation. Tractor-drawn cagewheel incorporation with 100 kg added N/ha contributed to the highest yield in both seasons.

Growth pattern (mean + SD conidial density × 10 7 /ml) of Beauveria bassiana on rice hull on different days of inoculation.

Days after inoculation Amount of substrate

Mass culture of Beauvaria

hull 1/2 bag (180 g) (A) 1.50 ± 0.14 5.80 ± 0.60 5.00 ± 0.12 3.90 ± 0.27 bassiana (Bals.) Vuill. on rice

15 30 35 40

3/4 bag (270 g) (B) 1.20 ± 0.19 5.00 ± 0.20 5.00 ± 0.11 4.90 ± 0.24

CV (%) = 7.71; CD 0.01 (between A and B) = 0.1907 and (between days) = 0.2696. D. Mazumder, K. C. Puzari, and L. K. Hazarika, Mycology Research Section, Assam Agricultural University, Jorhat 785013, Assam, India

Beauvaria bassiana (Bals.) Vuill. shows mass culturing was developed. An The bamboo piece was fitted on the potential as a biocontrol agent for many autoclavable polypropylene bag (33 × mouth of the bag with twine or a rubber

band (see figure). Nonabsorbent cotton

Mass culturing was used for plugging. Half to 3/4 of the B. bassiana on bag was filled with rice hull (soaked in rice hull in an water overnight), 2% dextrose, and autoclavable 0.05% chloramphenicol. Bags were polypropylene bag, a) hollow bamboo top, b) repeated for two consecutive days. cotton plug, and Inoculation was made with 1 ml of a c) polypropylene 1.17 × 10 7 conidia/ml suspension and bag with hollow incubated at 25 ± 1 °C for 40 d. The

insect pests of rice. To harvest large

are required. field, an easy, inexpensive process for diameter piece of hollow dry bamboo quantities of propagule to apply in the 17.5 cm) and a 3.5-cm-long × 3.2-cm-

bamboo top and cotton plug fitted on the mouth.

bags were shaken thoroughly every 5 d for uniform growth of fungus. Conidial population was determined at 15, 30, 35, and 40 d after inoculation (DAI). Twenty grams of substrate, obtained after thoroughly mixing the contents within each bag, was mixed in 70 ml of double-distilled water using Rottery mixture (Remi Motors, Remi Udyog, Bombay) for 20 min. The homogenate was filtered through muslin cloth and then through filter paper (Whatman no. 1). Conidia were counted from the filtrate using a haemocytometer (Naubauer, Fein-oplique, Beankenberg, GDR). The experiment was replicated five times and data were analyzed in a factorial complete randomized design.

Maximum fungal growth was obtained after 30-35 DAI (see table). Half-filled polypropylene bags yielded


Integrated pest management—diseases

sterilized at 20 lb pressure for 20 min,

the largest conidial population (5.8 × 10 7

bamboo pieces. This technique is supe- conidial population from 30 to 35 DAI (5 may be used to replace the hollow dry fourths-filled bags showed an unchanged

reduces contamination. Polypropylene pipes (autoclavable) numbers gradually declined. Three- made on the body of the bag because it declining. conidia/ml) at 30 DAI, after which rior to inoculating fungus through a slit × 10 7 conidia/ml), after which it started

Flight activity of Spodoptera fugiperda (J. E. Smith) in

Metarrhizium sp.: a new spray as a control. Pots were observed northeastern Colombia for dead insects every 24 h for 8 d. biocontrol agent for brown acid savanna ricefields in

planthopper management in The pathogen sporulated on the ricefields surface of BPH. Infected hoppers A. Pantoja, C. Garcia, and O. L. Mejia,

Centro lnternacional de Agricultura Tropical (CIAT), AA 6713, Cali, Colombia appeared green and died within a few

days. With the spore concentration used, we observed a significantly high mortal-

integrated pest management (IPM) df = 18). dynamics is needed for implementing ity of 64.8% (t = 16.97 at p = 0.05 and Precise information on pest population

J. M. R. S. Bandara and D. Ahangama, Plant Protection Laboratories, Agricultural Biology Department, University of Peradeniya, Peradeniya, Sri Lanka

Agronomic practices and use of certain In a similar experiment, concentra- programs. Since rice was introduced to insecticides are the reported causes of tions of 0, 6.4 × 10 3 , 6.4 × 10 4 , 6.4 × 10 5 , the acid savanna soils in northeastern increases in brown planthopper (BPH)

yields. Farmers often use up to two age mortality recorded was adjusted for epidemics in Sri Lanka, India, Philip- causes economic damage and reduced plants/pot) with standing water. Percent- reported to be responsible for BPH Spodoptera fugiperda (J. E. Smith) d-old-rice plants raised in pots (20 Continued use of insecticides was that the fall armyworm (FAW) were sprayed onto 18-d-old BPH on 30- Nilaparvata lugens (Stål) populations. Colombia, farmers have complained 6.4 × 10 6 , and 6.4 × 10 7 fungal spores/ml

pines, and Indonesia. mortality in control treatments using insecticide applications per season to We found that the fungus Abbott's formula (see table). The control the pest without knowing the

Metarrhizium sp. isolated from infected highest mortality rate (76%) was pest population dynamics and density. BPH in an untreated Sri Lankan ricefield observed on the seventh day after caused very high mortality in BPH spraying when a spore concentration of determine flying patterns of S. fugi- populations. Pathogenicity of the isolate 6.4 × 10 5 was used. Further increase or perda adults in commercial savanna AB301/1 was studied using BPH decrease in spore concentrations pro- rice-growing areas of Colombia. At collected from wetland ricefields. duced a lower mortality rate. It is each of three localities in the Cauca Healthy BPH were reared on 2-mo-old possible that while lower rates of spore Department, two sticky traps with rice plants of cultivar BG90-2 raised in concentration do not provide enough pheromone lures were placed within clay pots (10 cm diam, 15 cm high), coverage, higher concentrations show ricefields, 1 m above the ground. Lures with 2.5 cm standing water. Plants were self-limiting antagonistic effects on were replaced every 45 d. Adults/trap raised in a greenhouse at 30 ± 4 °C and infection. We propose that Metarrhizium were recorded twice a month. The mean 60-75% RH. Twenty-five 18-d-old BPH sp. be used as an effective agent in number of adults/month was calculated in these pots were later sprayed with an integrated pest management programs in for each locality (see table). atomizer containing 6.4 × 10 6 spores/ml combating BPH problems in wetland In general. the mean number of of Metarrhizium sp. Treatments were rice culture. adults/month was low across three replicated 10 times with distilled water localities. The most collected was 34

A 3-yr study was conducted to

males/trap during January at Santa Rosa

planted from April to early June. Eleven males/trap were counted at Matazul during July, but FAW population was 7 below 5 males/trap during most of the

(AB301/1). a Percentage mortality of Nilaparvata lugens treated with various concentrations of Metarrhizium sp. and La Libertad, although rice is

Days after treatment with spores Metarrhizium spores/ml concentration 1 2 3 4 5 6

6.4 × 10 7 0 0 0 3.3 0 0

6.6 16.6 26.6 30.0

20.0 33.3 year. This high number at Matazul 6.4 × 10 5

50.0 56.6

6.4 × 10 4 0 6.6 10.0 10.0 13.3 6.4 × 10 3

16.6 20.0 0 3.3 3.3 3.3 6.6

growing season, while the higher

6.4 × 10 6

0 6.6 10.0 26.6 33.3 53.3 76.6 coincides with the commercial rice-

6.6 10.0 infestation rates at Santa Rosa and La a Mortality values are adjusted for control treatment values using Abbott's formula. Libertad occur when no rice was in the

fields. This suggests that FAW popula-


Integrated pest management—insects

tion increases at Santa Rosa and La

Mean number of S. fugiperda (±SEM) in pheromone traps in three localties in Colombia, 1990-92.

Insects/trap (no.) (±SEM) Month

Santa Rosa La Libertad Matazul

January 33.2 ± 3.7 28.2 ± 3.2 6.0 ± 1.6 February 1.3 ± .3 1.9 ± 0.4 0.15 ± 0.1 March 4.6 ± 1.3 5.6 ± 1.6 0.81 ± 0.4 April 11.5 ± 1.9 8.0 ± 1.5 0.54 ± 0.2

June 21.3 ± 2.7 21.8 ± 1.9 10.11 ± 1.4 July 23.6 ± 3.9 13.8 ± 2.4 11.6 ± 1.4 August 16.6 ± 2.9 10.7 ± 2.0 2.6 ± 0.6 September 15.2 ± 7.8 7.1 ± 1.5 1.5 ± 0.4 October 17.5 ± 3.1 21.1 ± 10.3 2.9 ± 1.3 November 21.8 ± 2.8 18.6 ± 2.9 2.9 ± 1.3 December 20.5 ± 2.7 16.6 ± 2.9 1.4 ± 0.4

May 16.4 ± 2.3 8.5 ± 1.3 3.5 ± 1.0

Mean 15.6 ± 0.79 12.4 ± 1.00 3.8 ± 0.40

Libertad were related to weeds in the

on 6- to 90-d-old plants. and Santa Rosa was continuous during Matazul, adult flight activity was higher fields. Adult FAW activity at La Libertad the cropping season. However, at

No correlation was found between adult flight activity and larval damage on rice growing in acid soils. Population levels observed during the rice-growing season were low. Population levels observed in our study were low compared with FAW densities in other areas, suggesting that insecticide applications may not be necessary.

These findings will help farmers and IPM personnel make informed decisions about FAW control. Further research is needed to correlate adult flight activity with larval density and yield reduction, and to correlate FAW incidence with availability of alternate hosts.

Applying insecticides at early stage of rice cropping season may cause brown planthopper resurgence Jiaan Cheng and Zeng-Rong Zhu, Plant Protection Department and Institute of Applied Entomology, Zhejiang Agricultural University, Hangzhou, Zhejiang, 310029, China

Five fields (about 0.1 ha each) in northern Zhejiang Province were selected to test the effects of early insecticide application on brown planthopper (BPH) population dynamics during the second irrigated rice cropping season. Japonica rice varieties were transplanted in late July to early August.

In general, macropters immigrate into ricefields after transplanting and produce two generations (called generations 4 and 5 in Zhejiang) during the season. Damage to plants peaks with generation 5, around late September.

Each field was divided into three equal plots. Plot A served as the control, where insecticide was sprayed; plot B received one insecticide application at the early stage (about 20 d after transplanting) to control stem borer; and plot C was the same as B with an additional insecticide (buprofezin) application at the late stage to control BPH if the farmer thought it necessary (see table).


Mobile stages of BPH, its eggs, and main predators (spiders, mirids) were surveyed by tapping plants to make the insects and spiders drop onto a 30- × 40- cm plate that was placed at the base of the plants.

in the plots sprayed with insecticides Growth rates from generations 4 and 5

were significantly higher than those in the control plots of the same fields (t = 3.74, p<0.01) (see table). The key period affecting BPH population growth from generation 4 to 5 after insecticide spraying is during generation 4 nymph peak to generation 5 egg peak. Inappropriate spraying, including both the type of

Comparison of BPH growth rates under different insecticide treatments. Zhejiang, China.

Treatment a G5 b Egg/G4 c Peak G5 Peak/G5 Egg G5 Peak/G4 Peak Plot no. DAT Insecticide Growth Ratio Growth Ratio Growth Ratio

rate d to check rate × 100 to check rate d to check

1A Check e 16.35 18.96 3.11 1B 27 M+D 27.14 1.66 23.33 1.23 6.33 2.04 1C 27 M+D 38.62 2.36 21.96 1.16 8.48 2.73

2A Check 8.47 43.88 3.72 2B 23 M+D 8.70 1.03 41.91 0.96 3.65 0.98 2C 23 M+D 11.61 1.37 45.83 1.04 5.32 1.43

3A Check 27.20 14.16 3.85 3B 21 M+D 32.64 1.20 19.54 1.38 6.38 1.66 3C 21 M+D 39.02 1.43 14.46 1.02 5.64 1.46

4A Check 33.02 7.25 2.40 4B 18 Tri 69.49 2.10 10.48 1.45 7.28 3.03 4C 22 SCS+Tric 62.94 1.91 13.93 1.92 8.76 3.65

5A Check 26.72 36.65 9.79 5B 21 Tri 31.53 1.18 46.92 1.28 14.79 1.51 5C 25 SCS+B 50.00 2.25 32.00 0.87 16.00 1.63

Mean 1.65 1.23 2.01 SE 0.15 0.10 0.27 t 4.33** f 2.18 3.74**

a DAT= d after transplanting; insecticides: M = methamidophos; D = deltamethrin; Tri = triazophos; SCS = shachongshua (cartap-like); Tric = trichlorphon; B = buprofezin. b G5 = generation 5: c G4 = generation 4; d Growth rate = (BPH Count in stage (t+1)/(BPH count in stage t); e Check means no insecticide applied; f ** = mean is significantly greater than 1 (t = test, p<0.01).

BPH and its predator population dynamics in field 5, Jiaxing, Zhejiang, China. Insecticide applications: plot B, 21 Aug, triazophos; plot C, 25 Aug, a cartaplike insecticide + buprofezin.

insecticide used and the timing of an application, may cause BPH resurgence as a result of increased mortality of natural enemies.

An example of BPH resurgence is shown in the figure. The peak number of BPH eggs and nymphs + adults of generation 5 in plot B of field 5 were 1.5 times and twice as great as those in control plot A, respectively. While numbers of spiders and mirids in plot B were generally lower than those in plot A, the BPH-spider ratio was the highest (21.73) in the three plots. BPH and its major predators in plot C, after the first spray with buprofezin, were at the lowest level for the entire season.

Rice hull ash applied to seedbed reduces deadhearts in transplanted rice A. S. Sawant and V. H. Patil, Regional Agricultural Research Station (RARS),

Effect of rice hull ash (RHA) applied to seedbed on SiO 2 , content of seedlings, incidence of deadhearts, and grain yield of transplanted rice.

Konkan Krishi Vidyapeeth (KKV), Karjat 410201, Maharashtra, India, and N. K. Savant, lnternational Fertilizer Development Center (IFDC), Muscle Shoals, Alabama 35662, USA

Silica (SiO 2 ) in rice plants can provide protection from stem borer infestation. Greenhouse experiments conducted in 1990-91 showed that SiO 2 content of rice seedlings (IR36) increased when black or gray rice hull ash (RHA) was applied to the seedbed. We conducted two field trials to investigate the effect of RHA applied to the seedbed on the deadheart incidence due to yellow stem borer (YSB) ( Scirpophaga incertulas ) and on grain yield at a RARS experimental farm during 1991 and 1992 wet seasons.

Blackish-gray RHA, amorphous according to x-ray diffraction analysis, was prepared by burning hulls in an open field. Raised beds, to which RHA at 0, 0.25, 1.0, and 2.0 kg/m 2 was incorporated

The bars represent standard errors of the mean.

into the soil to a depth of 6-10 cm, were

in 1992. In 1991, 60 kg N/ha was split- adequate supply of Zn. and 4 replicates in 1991 and 5 replicates amended with 5% Zn-EDTA to ensure an complete block design with 10 treatments two splits as prilled urea (PU) or as PU experiment was laid out in a randomized Nitrogen was applied @ 4.6 g N/m 2 in 20- × 20-cm spacing (25 hills/m 2 ). The prepared before seeds of Jaya were sown. planted in 0.8- × 0.8-m microplot using

For each treatment, 16 hills of five 4- applied as PU and 15 kg P/ha was basally wk-old rice seedlings/hill were trans- applied as single superphosphate. Basally


deep-placed urea briquettes containing diammonium phosphate were used in 1992 to supply N and P at the same rates as in 1991.

The area surrounding the entire experimental plot was transplanted with Kolamba 540, a rice variety with high susceptibility to YSB. Artificial infestation was created by implanting one egg mass/four hills of Kolamba 540 at about 10 and 20 d after transplanting (DAT).

Total tillers and deadhearts were recorded at 30 DAT for the 16 hills in each plot. Data on percentage of deadhearts (using arcsin transformation) and yield were statistically analyzed. The 4-wk RHA-treated seedlings were

Prevalent insect pests of upland rice and some associated natural enemies in southeastern Nigeria S. O. Emosairue and E. J. Usua, Crop Science Department and Biological Sciences Department, University of Calabar (UC), Calabar, Nigeria

Rice cultivation has increased dramati- cally in Nigeria since 1986 because of the government ban on rice imports.

Rodents, birds, and insects are major contributors to low yields in farmers’ fields in southeastern Nigeria. We conducted this study during 1990 and 1991 early seasons (May-Aug) and late seasons (Sep-Dec) to provide information on prevalent insect pests and natural enemies in this rice agroecosystem.

The studies were conducted at the Teaching and Research Farm, Faculty of Agriculture, UC. ITA150 and ITA257, two popular early-maturing upland rice varieties developed by the International Institute of Tropical Agriculture were used. Each variety was planted in a 28.8 m 2 plot demarcated into four equal blocks of 7.2 m 2 and separated by a 1.75-m path. Four seeds of each variety were sown per hill at a spacing of 30 cm within rows and between rows. Plants were thinned to two per hill 20 d after sowing (DAS). A compound NPK fertilizer (15-15-15) was applied at 450 kg/ha in a split application, the first at 20 DAS and the second at booting.


chemically analyzed for SiO 2 content.

content and percentage of deadhearts. The RHA-treated seedlings looked healthier and stronger, and they produced more biomass than did the untreated seedlings. Increased SiO 2 content of seedlings and decreased deadheart incidence in transplanted rice were observed with up to 1.0 kg RHA/m 2 (see figure). Yields seemed to be protected from losses due to the deadheart damage.

These findings have two practical implications. As an incentive to collect RHA for use in growing healthy rice seedlings, farmers could start using rice hull-fired stoves, such as the Vietnamese

Zn-EDTA had no effect on the SiO 2

Lò Trâú, for cooking. This would help reduce their firewood needs. The lower deadheart incidence can be achieved without using insecticide, thus helping to protect the environment.

tory explanation as to why the yield increased when the SiO 2 content of the seedlings did not. One of our agronomic observations suggest that the RHA treatment improves plant vigor and, at times, increases the number of tillers/hill. This possible improvement in a yield-contributing factor may have increased grain yield. We will investigate this positive effect of RHA treatment on yield.

At this stage, we do not have a satisfac-

Relative abundance of the 15 most common Insect pests associated with upland rice varieties during early and late seasons in southeastern Nigeria.

Relative abundance (%) as affected by planting date a

Order Family Early Late

Species ITA150 ITA257 ITA150 ITA257

Coleoptera Chrysomelidae

Chaetocnema pulla 49.6 62.3 30.3 29.7

Altica nigrita (Lab.) 1.2 0.9 5.1 Dactylispa sp. nr. paucis- 1.7 0.7 0.2 0.3

Monolepta elegans (Allard) 1.5 2.3 0.1 0.0

Chnootriba similis (Mulsant) 10.4 5.1 4.9 4.4

chapuis (=zeae (Bryant))

pina (Weise)

Coccinellidae

Hemiptera Pyrrhocoridae

Dysdercus supertitiosus 0.2 0.0 32.3 26.9 (Fabricius)

Cicadellidae Cofana spectra (Distant) 16.0 10.6 11.9 12.0 Nephotettix modulatus (Mel.) 0.3 0.9 1.2 2.2

Aspavia armigera (Fabricius) 5.7 8.3 10.3 15.0

Stenocoris claviformis (Ahmad) 1.7 0.7 0.6 1.8 Mirperus jaculus (Thunbg.) 0.2 0.0 0.2 2.3

Poophilus costalis Walker 0.3 1.4 0.2 0.7

Cletus notatus (Thunbg.) 0.7 1.2 0.1 0.0

Locris erythromela (Walker) 1.0 0.5 0.2 0.2

Pentatomidae

Alydidae

Aphrophoridae

Coreidae

Cercopidae

Diptera Diopsidae

Diopsis spp. 4.0 4.2 2.2 4.5

Total no. of each species a Relative abundance (%) = x 100. Total no. of prevalent spp. =total number of

Total no. of prevalent species prevalent Insect species collected from the vegetative stage to harvesting of the crop during the different cropping periods.

0.0

Insect collection commenced 3 wk after crop emergence and was done twice a week, usually on Mondays and Fridays between 0700 and 0900 h; 1200 and 1400 h, and 1700 and 1900 h. During each sampling, three double-stroke sweeps were made of each block using a sweep net (30 cm diam, 75 cm deep). Total number of each insect species was recorded. This procedure was followed until rice was harvested.

One hundred arthropod species comprising insect pests, natural enemies, and a few insects with undefined roles were collected. (See table for the 15 most prevalent pests.) The predators encountered were reduviids, Rhinocoris segmentarius (Germ.) and R. bicolor (Fabr.); tettigoniid, Conocephalus conocephalus (L.); coccinellids, Cheilomenes sulphurea (Oliv.), Cheilomenes sp. and Scymnus sp.; and arachnids (spiders). The parasitic species encountered were the braconid, Agathis (subgenus Microdus ) sp., and the eumenid, Odynerus fervidus (Suss.).

Natural enemies were found mainly between the reproductive and ripening phases of the crop. Predators such as Cheilomenes sulphurea and Cheilomenes sp. were observed mainly on rice plants infested with the rusty plum aphid, Hysteroneura setariae (Th.), while spiders were observed feeding on small dipterous insects and cicadellid bugs such as Nephottetix modulatus (Mel.). In general, the overall population of natural enemies was higher on the late season crop. The tettigoniid, C. conocephalus and the teduviid. Rhinocoris spp., were the most abundant during both seasons.

population of grain feeders ( D. superstitiosus [see figure] and A. armigera ) on late season rice may cause some serious damage. Future work will focus on determining yield losses caused by these prevalent pests and on assessing the role of natural enemies in suppressing pests in this upland rice agroecosystem.

In conclusion, we believe that the high

Dysdercus superstitiosus (Fabricius) feeding on the developing grains of upland rice cultivar ITA 150 at the milky stage, Calabar, southeastern Nigeria, during the late season.

Rice yield losses to finches in Hill Region, Karnataka, India A. K. Chakravarthy, N. E. Thyagaraj, and J. B. Narendrakumar, Regional Research Station (RRS), Mudigere 5771 32, Karnataka, India

Six species of finches, house sparrow ( Passer domesticus ), Indian baya ( Ploceus philippenus ), white-throated munia ( Lonchura malabarica ), whitebacked munia ( Lonchura striata ), spotted munia ( Lonchura punctulata ), and black- headed munia ( Lonchura malacca ), were observed feeding on rice grains in the Hill Region of Karnataka. White-backed munia was the principal species. In this region, granivorous birds, such as parakeets and finches, are common.

of finches from the borders of a 4-ha ricefield planted with variety Intan at RRS, Mudigere (13.0° 7' N and 75.0° 37' E), during Nov-Dec 1990 and 1991, when finches begin to damage rice.

Munias arrived at the feeding site at around 0645 h in flocks and remained up to about 1745 h. Munias moved from their roosting sites to perch sites in trees. The birds then flew into the fields. They would alight on a rice plant and feed on

Using binoculars, we observed flocks

the adjacent plant. Their feeding range

Flock size varied from 75 to 280 birds/ha with an average of 105 (n = 50). Feeding period of munias lasted up to 27 d. The feeding rate of white-backed munia was computed at 8 grains/min (n = 55), with each feeding bout lasting up to 12 min (n = 100) and 3-15 min elapsing between bouts. The birds preferred to feed on milky grains, with the munias (irrespective of species) picking significantly more (91%) milky grains than mature grains (21.53%) (t, d.f. @ 0.05 = 8.66) (n = 60) from two adjacent fields. However, birds fed on mature grains in the absence of milky grains.

product of feeding rate/bird × bird/area × time spent in feeding/day × feeding days. Yield loss was converted to an on- weight basis (g) and expressed as a percentage of loss/ha (t/ha) by finding the weight of 1,000 grains (n = 3). Yield losses were categorized as depredative (grain consumed) and extra depredative (grain spilled) at milky (135-140 d) and mature grain (160- 165 d) stages. The depredative loss (43%) exceeded the extra depredative (16%) losses with t test

was 3-4 ha.

Yield loss was measured by a mean


Integrated pest management—other pests

showing significant differences (t, d.f @ 0.05 = 4.76) between the two. Total yield loss caused by finches was about 100 kg/ ha, which is affordable. However, when

Effect of plant density on methane emission from transplanted rice N. K. Savant, G. Carmona, and E. R. Austin, lnternational Fertilizer Development Center (IFDC), P. O. Box 2040, Muscle Shoals, Alabama 35662, USA

An agronomic practice that helps to increase rice production should be environmentally benign. Increasing the plant population is one of the crop management practices considered for increasing rice productivity. However, because the rice plant acts as a conduit through which CH 4 produced in the soil

all species of birds including parakeets, are considered, losses were found economically important.

is transported to the atmosphere, increasing the plant population could have an adverse effect on the environment if CH 4 emission is increased.

density on CH 4 emission by transplanted rice, a greenhouse experiment was conducted in 1993. In plastic-lined wooden boxes (1.0 m × 0.5 m × 0.3 m), 120 kg of Guthrie soil (Typic Fragiaquults, pH 6.5 after flooding, 2.2% organic matter, 48% silt, 30% clay) was submerged for 1 wk and then puddled. Chopped rice straw (about 3 cm) at the rate of 2 t/ha was incorporated 3 wk before transplanting 4-wk-old IR36 rice seedlings. Fertilizers were applied at rates of 60 kg N/ha as prilled urea, 15 kg P/ha as triple superphosphate, and 80 kg K/ha

To investigate the effect of plant

as potassium chloride. Plant densities, geometrics, and spacing used are illus- trated in Figure 1. Four seedlings were transplanted/hill for all spacings; for the regular 20- × 20-cm spacing, 10 seedlings/hill were also transplanted.

Methane emissions were measured from 0800 h to 1100 h, using the static Plexiglas chamber technique (Fig. 2c). Each chamber covered 4 hills. Ten-ml plastic syringes fitted with Mininert syringe valves were used to take air samples from the chambers immediately after installation and after 30 min. A gas chromatograph (Hewlett Packard, Model 5830 A. equipped with a flame ioniza- tion detector and a Poropak Q column) was used to determine CH 4 concentrations of the air samples collected at 26,

1. Transplanting geometries, spacings, plant densities (hills/ m 2 ), and areas covered by Plexiglas chambers used for measuring CH 4 emission from 4 rice hills.

2. Methane emission from transplanted rice (IR36) over time as influenced by plan density. Inset (c) illustrates the static Plexiglas chamber technique used. IFDC, 1993.


Environment

33, 40, 47, and 55 d after transplanting (DAT).

As the number of hills/m 2 increased from 25 to 66 (Fig. 2a) and the seed- seedlings/hill increased from 4 to 10 Fig. 2b), CH 4 emission increased up to 33 DAT. At 26 DAT, emission increased from 20 to 34 mg CH 4 /m 2 per h as the number of hills/m 2 increased from 25 to 66. This effect of plant density on CH 4 emission, however, diminished with time and disappeared at 40 DAT. This suggests that other plant factors, such as root development and tiller formation,

influenced the effect. When the root systems of the transplanted seedlings are small and limited, the additional hills/m 2

and/or tillers/m 2 may effectively serve as additional conduits for transporting more CH 4 from the soil to the atmosphere during the first 33 DAT. Thereafter, the roots of the rice plants develop and spread through a larger soil volume, thereby reaching more CH 4 produced farther away from the plants. During the same period, the number of tillers/hill will increase with time. AT 33 DAT, there were 48 and 41 tillers/4 hills for

plant densities of 25 and 66 hills/m 2 , respectively.

the regular and modified 20- × 20-cm spacing and 4 seedlings/hill were the same (data not reported), probably because both spacings have the same plant density of 25 hills/m 2 (Fig. 1).

These results suggest that plant density is an important factor and therefore should be defined in field measurements of CH 4 emission from flooded rice, especially during the first

The CH 4 emissions from plants with

month after transplanting.

Socioeconomic impact Labor allocation in rice cultivation in Western Himalaya, Himachal Pradesh, India B. Bala, R. K. Sharma. and T. V. Moorti, Agricultural Economics Department, Himachal Pradesh Krishli Vishvavidyalaya, Palampur 176062 (H.P.), lndia

Rice cultivation is a labor-intensive activity that provides employment, particularly to poor and landless female

workers. Despite their active participation in this work, few studies have quantified their labor contributions—particularly for unpaid family labor. Thus, their participation had been underestimated in agricultural statistics. This study was conducted to examine the labor contributions of female and male workers (family and hired) in rice cultivation for different categories of farm and crop operations, to identify constraints to increasing rice productivity with special emphasis on

farm women, and to recommend interven- tions to improve their status.

We hypothesized that female participation decreases as farm size increases. We surveyed 120 households in 10 villages in two blocks of Kangara District of Hima- chal Pradesh. Farms were classified as marginal (<1 ha) (60), small (1-2 ha) (33), and large (>2 ha) (27).

Rice farming is the major source of livelihood in this district. Farmers also grow wheat, maize, millet, and sugarcane.

Share of female labor to total labor input (%) in rice cultivation by activity and farm size. Kangara District, Himachal Pradesh, India.

Farm size

Marginal Small Large All farms

Total labor Female labor Total labor Female labor Total labor Female labor Total labor Female labor input to total labor input to total labor input to total labor input to total labor

Activity

input input input input

Land preparation

Planting

lnterculture

Hatvesting

Postharvest

Others

13.2 (17.16) a

25.0 (32.50)

17.6 (22.88)

32.8 (42.64)

10.3 (13.39)

1.1 (1.43)

45.0 (7.72)

57.2 (18.59)

63.2 (14.46)

51.8 (22.09)

74.0 (9.91)

40.0 (0.57)

11.7 (17.67)

24.9 (37.60)

21.8 (32.92)

30.5 (46.05)

8.9 (13.44)

2.2 (3.32)

41.4 (7.32)

60.8 (22.86)

55.2 (18.17)

55.6 (25.60)

81.7 (10.98)

11.4 (12.31)

24.6 (26.57)

20.9 (22.57)

30.6 (33.05)

9.4 (10.15)

3.1 (3.35)

38.7 (4.76)

57.6 (15.30)

53.3 (12.03)

48.2 (15.93)

71.6 (7.27)

12.1 (15.83)

24.7 (32.31)

20.2 (26.42)

31.3 (40.95)

9.6 (12.56)

2.1 (2.75)

41.6 (6.58)

58.6 (18.93)

57.3 (15.14)

51.8 (21.21)

75.8 (9.49)

13.3 (0.36)

Total 100.0 52.6 100.0 54.8 100.0 51.2 100.0 52.9 (130) (68.38) (151) (82.75) (108) (55.30) (130.82) (69.20)

a Figures in parentheses indicate labor days/ha.


- -

M. Wijeratne and I. R. N. Abeydeera, Agricultural Economics Department, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka

Inappropriate use of agrochemicals has become a major problem in rice farming. Training and extension programs are often conducted to educate village extension workers (VEWs) and farmers on the correct use of agrochemicals.

A study was conducted in Matara District of Sri Lanka to estimate the knowledge gap between VEWs and

farmers for six practices involving agrochemicals: seed treatment, weed control, fertilizer application, insect pest control, disease control, and precautionary techniques. Standard recommendations were used to determine the main knowledge elements for the practices. For example, elements for fertilizer application were dilution rate, dose, application frequency, timing, and method of application. A scoring procedure was applied

Results from the survey showed that total labor input on marginal, small, and large rice farms was 130. 151, and 108 d/ha, respectively, of which 3.4% for marginal, 4% for small, and 14% for large farms was hired labor (see table). Women consistently contribute more labor than men across farms and in all operations except land preparation.

share of total labor input was highest (83%) on small farms, followed by marginal farms (68%) and large farms (55%). Women, particularly from low- income rice farming families, are involved in almost all the rice operations except plowing, although they do help men make embankments and level soil. In land preparation, female laborers from marginal farms contributed 45% and from small farms, 41.4%. Those from large farms contributed 38.7%.

is sown by physical transplanting with family rather than hired labor mostly supplying the labor. Female workers contributed 57.2% of the total labor for transplanting on marginal farms, 60.8% on small farms, and 57.6% on large farms. The extent of hiring labor for

Women’s contribution as a percentage

More than 70% of the rice cultivated

marginal, small, and large farms was 18.6%, 43.2%, and 29.5%, respectively. Only female laborers were hired on all farms because, according to the employ- ers, they are more efficient than men for this task.

Interculture operations, mainly weeding, were generally performed jointly by male and female workers, although females’ contribution was highest (63%) on the marginal farms. Weeding is done in August, which is the time that female family members enrolled in school are on vacation, and they provide the required additional labor in this activity.

Among the different operations, the labor contribution of female workers was highest (more than 70%) in postharvest activities (threshing, winnowing, drying, and hauling). Female workers contribute more labor in postharvest because rice harvesting and postharvest activities must be finished quickly so that farmers may use the residual soil moisture for the following wheat crop. Farmers usually hire women laborers from poor and landless families. Forty-three percent of the labor input for harvesting rice for all farms was hired, 77% of which was supplied by female workers.

Education and communication Knowledge gap on agrochemical use in rice farming

Despite the significant contributions of women, they received lower wages than did men for the same tasks.

Female family members in Kangra District contribute significantly to almost all rice production tasks and provide the bulk of unpaid family labor operations. Female workers contribute a higher percentage to total labor input on marginal and small farms than on large farms.

Because female family members provide most of the labor in rice, they should be trained on improved cultural practices in production. In-depth studies should be done to better understand women’s traditional practices in postharvest methods as well as their knowledge, attitudes, and perceptions about rice seed selection, management, and storage.

extension services in the community. Innovative participatory methods of imparting improved technologies should be designed, taking into consideration women’s levels of education and house- hold responsibilities.

Women should be direct recipients of

Differences in knowledge levels between village extension workers (VEWs) and farmers. a Matara District, Sri Lanka.

Av score t value between Standard

Practice score for Village Farmers Standard Standard VEWs and recommendation extension (n=50) recommendation recommendation farmers

workers and VEWs and farmers (n=25)

Seed treatment 3 2.4 1.18 5.2*** 18.3*** 5.65*** Weed control 6 3.68 2.28 18.4*** 26.2*** 2.50* Fertilizer application 5 3.64 2.82 14.1*** 25.5*** 3.92*** Disease control 4 2.44 1.66 13.4*** 19.9*** 2.71*** Pest control 4 2.96 1.92 12.8*** 18.3*** 4.74** Precautionary techniques 6 4.04 3.06 16.0*** 22.3*** 3.86***

a *, **, *** = significant at 5%, 1%, and 0.1% level, respectively.


to the elements to give each a standard score. A questionnaire was developed to test the knowledge of VEWs and farmers.

The field investigation was conducted during 1992-93 maha (wet) season. Twenty-five VEWs and 50 rice farmers were randomly selected for the survey. An average score for each practice was

calculated separately for VEWs and farmers (see table).

Standard recommendation scores and those of VEWs and farmers were significantly different for all the practices tested. Knowledge levels between VEWs and farmers also show highly significant differences for four practices. This

evidence reveals a knowledge gap between standard recommendations and VEWs’ knowledge level and between VEWs’ and farmers' knowledge level. VEWs would benefit from intensive training programs on agrochemical use, and farmers from effective extension techniques to disseminate this information.

Research methodology Path analysis of focus expansion in rice sheath blight N. P. Castilla, M. A. Ynalvez, and C. G. McLaren, IRRI; and S. Savary, IRRI-lnstitut Français de Recherche Scientifique pour le Développement en Coopération

The effects of four factors on focus expansion in sheath blight were studied in the field: N supply, leaf wetness, contact frequency, and inoculum source characteristics. Experiments were conducted during the 1992-93 wet season (WS) and dry season (DS) at IRRI using IR72 and a 20- × 20-cm spacing. Both experiments were laid out in a split-plot design with eight replications.

Main plots consisted of three N input levels applied as urea: 0, 80, and 120 kg N/ha. Subplots comprised hills spaced at 15 × 15 cm, with the central source hill representing the inoculum source. Five subplot treatments were represented by different structures of the inoculum source resulting from different inoculum amounts and positioning: 5 g or 15 g of inoculum, inoculum placed at the upper or the lower layer of the plant canopy, and a noninoculated control. The inoculum consisted of a 5:1 rice grain/hull mixture colonized by an isolate of Rhizoctonia solani Kühn belonging to anastomosis group 1. The source plants were inoculated during the maximum tillering stage.

the maximum distance in cm between lesions along rows (length of focus, 1) and across rows (width of focus, w) on both sides of the source. It was computed as: a = (1xw)/4. Assessments were made at weekly intervals after inoculation.

The area of a focus (a) was assessed as

Path diagram of the effects of nitrogen content in the leaves (N), area under leaf- to leaf and leaf- to-sheath contact progress curve (C), area under leaf wetness progress curve (W), initial sheath blight severity on the lower layer (L), and initial sheath blight severity on the upper layer (U) of the source plant on the log- transformed mean rate of focus expansion (F) (see table).

Explanatory variables used in path analysis.

Variable Description Unit

N Area under the progress curve of the N % day content in the leaves.

W Overall wetness of the canopy throughout the cropping season (product of mean leaf wetness rating and mean dally rainfall during the cropping season).

C Area under the progress curve of the number of leaf-to-leaf and leaf-to-sheath contacts. % day

L Initial sheath blight severity on the lower layer % of the source plant.

U lnitial sheath blight severity on the upper layer % of the source plant.


The initial sheath blight severity on the source plants was determined 12 d after source establishment as the percent leaf and stem areas covered by lesions on a sample of five tillers. Leaf wetness assessments at the upper, middle, and lower layer of the crop canopy were made using a four-point assessment scale where 0 = dry, 1 = few, scattered, big droplets, 2 = thin film of small droplets, and 3 = dense film of small droplets. All assessments were made at 0600 h and data were taken on 10 dates after inoculation on a sample of 10 hills in each N treatment.

Contact frequency between plants was assessed during stem elongation, booting, and ripening stages from counts of leaf- to-leaf and leaf-to-sheath contacts of a reference hill with its neighbors.

Hills were sampled during the same growth stages to determine the percent N content using the Kjeldahl method.

The mean rate of focus expansion (R) was computed as:

where n = the number of observations (six for each experiment), ai = the focus areas in cm2 at sample time i, and ti= the number of days after inoculation at sample time i.

ments were combined and averaged across replicates. Path analysis was performed with the log-transformed mean rate of focus expansion (F) values as the response variable and the variables listed in the table as regressors.

The path diagram (see figure) suggests a marginal direct effect of N content on the rate of focus expansion, and strong indirect effects via canopy wetness and contact frequency. The analysis suggests that the latter two variables might be major driving factors in disease spread. The direct effect of initial severity on the upper leaf layer of the source plant on focal expansion is stronger than that of initial severity on the lower layer.

The data from the WS and DS experi-


Path analysis can be used to describe complex data sets by means of direct and indirect effects on a response variable despite the confounding effects caused by multicollinearity of the explanatory variables. This study further demonstrates

that path analysis can be a useful tool in understanding the rice-sheath blight pathosystem by showing which variables exert influences on the spread of the disease and by uncovering the influences of these variables on each other.

Selection of protein content of upland rice grain using chlorophyll content H. Nemoto, M. Hirayama, M. Miyamoto, K. Okamoto, and R. Suga, Plant Biotech- nology Institute, lbaraki Agriculture Center, Kamikunii, Mito, lbaraki 311-42, Japan

Breeding for protein content is important to improve the nutritive value and taste of rice. However, the complicated analysis of protein content is inadequate as a breeding technique. We tried to establish a method for selecting protein content of brown rice by measuring chlorophyll content before harvest.

Fourteen varieties of both Japanese upland and lowland rices were cultivated under the usual conditions. The chlorophyll content of the top unfolded leaves of five plants of each variety was measured about every 2 wk with a chlorophyll-measuring instrument (SPAD-502, Minolta). After harvest, protein content

~

of brown rice was measured by Kjeldahl method.

Chlorophyll content and protein content of both upland and lowland rice were not correlated until 15 d before heading (DBH). However, chlorophyll content of upland rice from 15 DBH correlated significantly with protein content. Lowland rice also had a significant relationship between chlorophyll content 15 d after heading and protein content. Chlorophyll content plays an important part in protein accumulation in grain, especially in upland rice.

Parent-offspring correlation was measured in the chlorophyll content of 36 breeding lines in advanced generations between 1992 and 1993. A significant relationship was observed in chlorophyll content between generations ( r = 0.778*). It is therefore possible to select upland rice lines with low or high protein contents by measuring chlorophyll content about 2 wk before heading.

Parent-offspring correlation on chlorophyll content of upland rice lines. Ibaraki, Japan, 1992-93.

Correlation coefficients between protein content of brown rice and chlorophyll content in upland and lowland rice. a Ibaraki, Japan.

Rice Measuring data (day) Variety

No. –45 –30 –15 Heading +10 +15 +25

Upland 14 –0.018 0.297 0.891** 0.872** 0.792* 0.945** 0.942** Lowland 14 –0.512 0.332 0.339 0.614 0.579 0.849* 0.812*

a *, ** = significant at the 5% and 1% probability level, respectively.

n-1 S (a i +1-a i )/(t i +1-t i )

i=1 R =

n-1

DNA fingerprinting of Xanthomonas oryzae pv. oryzae by ligation-mediated polymerase chain reaction

M. L. C. George, IRRI; W. T. Cruz, Philippine Rice Research Institute, Maligaya, Muñoz, Nueva Ecija, Philippines; and R. J. Nelson, IRRI

The polymerase chain reaction (PCR) is a fast and extremely sensitive method that can be used to detect and fingerprint pathogens. In this study, ligation- mediated polymerase chain reaction (LMPCR), a method that amplifies DNA flanking a particular DNA sequence, was used to fingerprint isolates of Xantho- monas oryzae pv. oryzae (Xoo), the causal organism of bacterial blight, and to distinguish between Xoo and another closely related rice pathogen, X.o. pv. oryzicola (Xocola), the causal organism of bacterial leaf streak.

The LMPCR scheme is presented in Figure 1a. The method makes use of two primers and a nonphosphorylated Eco RI- compatible linker (Fig. 1b) that contain sequences found in IS1113, an insertion sequence originally isolated from Xoo that hybridizes to both Xoo and Xocola DNA. The linkers serve as priming sites distal to the insertion sequence.

Genomic DNA samples were diluted to a concentration of 20 ng/µl and digested to completion with 20 units of Eco RI per µg of DNA. Five µ l of digested DNA and 10 µl of the linker (50 pg/µl) were mixed together, warmed to 45 °C for 5 min. then chilled in an ice bath. Five µl of buffer mixture containing 2 µl of 10X ligation buffer (Boehringer Mannheim) and one unit of T4 DNA ligase were added, and the resulting mixture was incubated at 15 °C for at least 4 h.

Amplification was performed in a total volume of 20 µl containing 1 µl of the ligated DNA mixture, 2 µl of 10X Taq incubation buffer (Boehringer Mannheim), 185 µM of each dNTP, 0.5 µM of each primer, and approximately 2.5 units of Taq polymerase. The reaction mixture was overlaid with one drop of mineral oil, initially denatured for 3 min at 94 °C, and then subjected to 30 cycles

1. a) LMPCR scheme. Eco Rl digestion generates cohesive ends compatible with the linkers. Since the linkers are nonphosphorylated, only the 5' ends of the DNA fagment get ligated

to the linkers. Thin arrows represent annealed primers that do not proceed to the amplification step. b) The sequences of the linker and the two primers.


2. LMPCR fingerprints of representa- tive Xoo isolates. Letters denote IS1113-based restriction fragment length polymorphism groupings. Lane c, no template control; and lane m, molecular weight markers.

of PCR (1 min denaturation at 94 °C, 1 min annealing at 62 °C, and 2 min extension at 72 °C) and a final extension for 7 min at 72 °C using a Perkin Elmer Cetus DNA thermal cycler. The products were visualized in a gel containing 0.5% agarose and 0.75% Synergel ™ (Diversi- fied Biotech, Newton, MA, USA) after staining with ethidium bromide.

Using this method, bands were amplified from Eco RI-digested and ligated Xoo DNA. No bands were amplified from the undigested DNA or from the digested and unligated DNA

Primers for the amplification of rice tungro bacilliform virus DNA genome by polymerase chain reaction S. R. Venkitesh, A. C. Dolores-Talens, and H. Koganezawa, IRRI

The polymerase chain reaction (PCR) technique allows the amplification and rapid recovery of specific viral sequences from complex mixtures of DNA derived from infected host plant or viruliferous insect vectors. Optimization of individual reaction component quality and concentrations (Taq polymerase, MgCl 2 template DNA, and primers) as well as optimization of temperature and time profiles are necessary to ensure the best reproducibility and efficiency of PCR.


controls. The Xoo DNA fingerprints consisted of 1-7 amplified fragments, ranging in size from 250 bp to 1.3 kbp long (Fig. 2).

While LMPCR generated consistent and reproducible fingerprints for Xoo, it yielded only a single 2.5-kbp band in 4 of the 29 isolates of Xocola tested. Further- more, this single band or another higher molecular weight band was more fre- quently seen in the digested but unligated Xocola DNA controls. LMPCR of four DNA samples each from Oryza sativa, Magnaporthe grisea, and Pseudomonas

We designed 11 sets of 20-mer primers according to the published sequence of rice tungro bacilliform virus (RTBV). Antisense primer and sense primer of all adjacent primer sets overlapped each other. PCR conditions were optimized to amplify 11 overlapping DNA fragments that covered 100% of RTBV DNA genome (see table).

The total nucleic acid extract was prepared by grinding 2 to 3-cm-long infected leaf pieces in a mortar and pestle containing 2X CTAB buffer plus traces of 2-mercaptoethanol. After grinding, the samples were extracted with chloroform- isoamyl alcohol mixture and precipitated with 70% isopropanol at -20 °C for 2 h. DNA pellets were oven-dried and suspended in TE buffer (10 mM Tris-HCl + 1 mM EDTA, pH 8). For PCR amplifi-

sp. yielded no bands. Southern hybridization of EcoRI-digested DNA using IS1113 as a probe confirmed the absence of IS1113 sequences in these samples.

Visual inspection of the LMPCR fingerprints of 74 Xoo isolates showed a good correspondence with their groupings using IS1113-based restriction fragment length polymorphism patterns (Fig. 2). This study shows that LMPCR has potential as an alternative strategy for fingerprinting Xoo isolates and as a diagnostic tool for differentiating XOO

from Xocola.

cation, about 100 mg of total nucleic acid extract of leaf tissue was incubated in a thin-walled Gene Amp reaction tube containing 1X PCR buffer (50 mM KCl, 10 mM Tris-HCI, pH 8.3), 2.5 units (0.5 µl) Taq polymerase, 0.5 µM each of two primers, 0.2 mM of each dNTPs, and 4 mM MgCl 2 in a total reaction volume of 100 µl. The PCR products were analyzed with an ethidium bromide- stained 2% agarose gel in 1X TBE buffer using two size markers, one ranging from 50 bp to 1000 bp and the other from 1000 bp to 3000 bp. Except for primer sets 3, 4, and 7, all PCR amplifications were carried out for 40 cycles with a denaturation temperature of 94 °C for 1 min, annealing temperature of 53 °C for 2 min and extension temperature of 72 °C for 3 min, followed by final extension tem-

Primer sets for the amplification of RTBV DNA.

Sequence Amplifying region PCR product size

sense and antisense (bp positions) (bp)

5'-TGGTATCAGAGCGATGTCG-3' 1-1052 1052 5'TCAGAGGTTGAATCTTGGGT-3'

Set 2 5'-AGTGGAAGTAGTTCAGCAGG-3' 5'-TTCATTCCCATCTAGGTGTG-3'

893-1740 848

Set 3 5'-GCCGGTTGTGGAGTGTTCTA-3' 1471-2718 1248 5'-TCTACCATCCATCCAAGACC-3'

Set 4 5'-GGTCTTGGATGGATGGTAGA-3' 2669-4165 1467 5'-GCTGAGGTGCTACATAGGTT-3'

Set 5 5'-CCTGTGAAACCCAATACTGC-3' 3596-4669 1074 5'-ATGCTGCTGTTCTATGCCTG-3'

Set 6 5'-CAACAGCCAGACACGAACTT-3' 4271-5481 1211 5'-CCAGCCTTCTTCTGACGCAT-3'

Set 7 5'-CAGATGCGTCAGAAGAAGGC-3' 5459-6612 1154 5'-CAGTCCAGTATCCAGCTTCA-3'

Set 8 5'-AGAGTGCCTAACTAAGGTCG-3' 6011-7169 1159 5'-TGTGGTGCAGGACATTGTGT-3'

Set 9 5'-CCTCGCTGGAACTTCAATGA-3' 6888-7522 5'-AAGACGACTACTCACTGACC-3'

635

Set 10 5'-CAAGGTTCCTGAAGGGCTAC-3' 6794-7891 1098 5'-TTGGTATCCACACTAGCAGA-3'

Set 11 5'-GTACCGTCAGGCCGTGTTAT-3' 5'-GCTCCTGCTGAACTACTTCC-3'

7718-915 1200

PCR products resolved in 2% agarose gel, stained with ethidium bromide, and visualized by UV illumination. Lanes 1 and 13 = size markers (100-300 bp

respectively; lanes 2-12 = PCR products produced from amplification reactions using 11 primer sets (primer set 1 to primer set 11).

and 1000-3000 bp),

perature of 72 °C for 6 min. For primer sets 3, 4, and 7, amplifications were carried out for 38 cycles with a denaturation temperature of 94 °C for 1 min, annealing temperature of 43 °C for 1 min, and extension temperature of 72 °C for 5 min. A 50 µl oil overlay was used to prevent refluxing of the sample. Total nucleic acid extracts from infected and uninfected rice leaves were used as positive and negative controls, respectively, and examined by agarose gel electrophoresis.

Results of the amplification, the corresponding PCR products derived by using each primer set, are shown in the figure. Using these 11 sets of primers, we are now able to amplify any part of the RTBV genome from tungro-infected plant DNA extract.

Clonal propagation of thermosensitive genic male sterile lines in rice Xiao Guoying and Tang Li, Hunan Hybrid Rice Research Center (HHRRC), Changsha 410125, China

A simple and reliable technique for clonal propagation of thermosensitive genic male sterile (TGMS) lines was developed. Mature seeds (735) of a TGMS line were dehulled, soaked in 75% ethanol for 1-3 s, and washed in running tap water for 10 min. Seeds were disinfected for 10 min in 0.1% HgCl 2 solution and then rinsed three times in sterile distilled water. The seeds were germinated in a 100-ml flask containing half strength Murashige and Skoog's (MS) (1962) medium with 0.6% agar and 1.5% sucrose. Shoot base segments (5 mm long) were excised under aseptic conditions from 2-wk-old seedlings. They were then cultured in flasks containing about 5.0 ml of agar-solidified MS medium supplemented with 2 mg benzylamino- purine (BAP)/liter and grown under 10/ 14-h light/dark (L/D) photoperiod at 25°C. After 4 wk of culture, proliferated shoots were counted, and then subcultured under the same conditions. The solidified MS medium with 0.1 mg naphthalene acetic acid (NAA)/liter was used for rooting.


Set 1

Effect of cytokinins on shoot proliferation. a

First subculture Second subculture Third subculture Phytohormone Initial (2 mg/liter) shoots Shoots Shoot Shoots Shoot Shoots Shoot

(no.) (no.) proliferation (no.) proliferation (no.) proliferation (%) (%) (%)

Benzylamino- purine (BAP) 48 139 289.6 498 358.3 1632 327.7

Kinetin 38 74 194.7 184 248.6 475 258.2 Zeatin 73 101 138.4 189 187.1 430 227.5

a Subculture interval = 4 wk.

The medium supplemented with BAP ent concentrations of BAP showed that 2 produces the best response for shoot

proliferation. When the concentration of proliferation (see table). A test of differ- mg BAP/liter is optimum for shoot

BAP is increased to 4 mg/liter, there are some shoots with abnormal plant type and unfavorable leaf color even though the proliferation rate is reasonably high. After getting enough shoots by subculture, the proliferated shoots can be separated and transferred onto rooting medium, on which almost all of the shoots grow roots. About 1,000 regener- ated plantlets were transferred into soil in the summer. Visual observation showed all plants to be normal.

Greenhouse rearing and

bug were produced on each potted plant, and age. rating scale for rice mealy tion (25 DAI), about 360 adult females significantly influenced by host plant

Based on these observations, we 5 d later, crawlers emerged. Gravid developed a procedure for mass-rearing females collected from leaf sheaths were

R. Velusamy and S. Jeyarani, Entomology

University (TNAU), Coimbatore 641003, Using an adhesive (Camilin), five gravid Department, Tamil Nadu Agricultural B. rehi in the greenhouse (see figure).

females were attached to the auricles of Procedure for India; and R. C. Saxena, lnternational Centre potted 60-d-old TN1 plants at the rate of greenhouse rearing of Insect Physiology and Ecology (ICIPE),

one female/tiller. The plants were then of rice mealy bug and Kenya

covered with a mylar film cage (90 cm screening of rice cultivars for

Rice mealy bug Brevennia rehi Lindinger high, 10 cm diam). By 25 d after infesta- resistance. possesses behavioral attributes that made earlier attempts for mass-rearing in the greenhouse unsuccessful: a) at all stages (except crawler), the pests are sedentary and remain under the leaf sheath, making their handling tedious and time consum- ing; b) the soft-bodied females are sensitive to handling and do not settle on plants if disturbed; and c) insect longev- ity, fecundity, and population increase are

Reactions of rice varieties to B. rehi in the bulk seedling test.

Variety Plant damage rating a

Co 9 3 d Co 18 1 e Co 21 1 e Co 22 1 e Co 23 5 c Co 25 7 b Co 26 9 a Co 27 9 a Ptb18 9 a Ptb21 1 e Ptb33 3 d TN1 (susceptible check) 9 a

a Av of 5 replications. See text for definition of scale.

different (P=0.05) by DMRT. Means followed by a common letter are not significantly


held in a petri dish lined with moist filter paper and used for infesting plants. Crawlers that emerged were used for greenhouse screening of rice cultivars.

To screen for resistance, pregermi- nated seeds of 12 rice varieties were sown in seedboxes laid out in a randomized complete block design and replicated five times. When seedlings were 7 d old, the seedboxes were placed in a water-filled galvanized iron tray and

infested with 5-6 crawlers/seedling. TN1 plants loaded with crawlers from the stock culture were held horizontally above the seedboxes and tapped gently so that crawlers were dislodged and distrib- uted uniformly on the test seedlings.

At 20 DAI when about 90% of susceptible check TN1 plants were dead, the varieties were rated for plant damage on a 0-9 scale where 0 = no damage, 1 = slight damage, 3 = first and second leaves

of most plants partially browning, 5 = pronounced browning and stunting or about half of the plants wilting or dead, 7 = more than half of the plants wilted or dead and the remaining plants severely stunted and covered with a mealy coating, and 9 = all plants dead. Plants with negligible damage were considered resistant. Using this test, varieties Co 18, Co 21, Co 22, and Ptb21 were rated resistant (see table).

News about research collaboration Identifying decline

factors in yield

A new method to isolate specific fractions of soil organic matter (SOM) has been developed by IRRI scientists investigating the causes of yield decline that occurs in many long-term experiments on intensive, irrigated rice systems in the tropics. SOM represents the largest soil reservoir of soil nitrogen, and release of nitrogen from the SOM pool supplies

much of the nitrogen required by the rice crop.

A puzzling aspect of the yield decline is that the amount of nitrogen supplied by soil decreases over time despite the conservation or even increase in SOM. Unlike most other crops which are grown in aerated soil, rice is mostly grown in flooded soil in lowland ricefields.

With funding from the United States Agency for International Development, IRRI scientists Dan Olk and Ken

Cassman are trying to determine if changes in the chemical structure of SOM can help explain the decrease in soil N supply that occurs without a corresponding reduction in SOM content.

cal characterization of these SOM fractions will help identify the factors contributing to the yield decline and will increase understanding of soil quality and sustainability of intensive rice systems.

Olk and Cassman believe that chemi-

A new rainfed lowland rice Extensive rice research research institute in India training program in Lao PDR A new rice research institute will soon rise in Assam, India’s most northeasterly state. The institute, supported by a project under development by the Indian Council of Agricultural Research, will be dedi- cated to research in the rainfed ecosystems of eastern India.

Assam has a total rice area of about 2.4 million ha, 90% of which are rainfed. About 2 million ha of its rice area are flooded every year and an average of more than 300,000 ha of rice are de- stroyed due to flooding. Assam is flood- prone because Meghalaya and Chirapunji receive the highest rainfall in the world, more than 5,000 mm each year; and Assam has the world’s largest river island, the Majuli Island.

The 25-ha rainfed lowland rice research station will focus on flood-prone environments. Emphasis will be placed on submergence tolerance of rice. Institutions and key scientists from all states of eastern India will be involved.

One of the most serious constraints to improving agriculture in the Lao People’s Democratic Republic has been the lack of adequate research capacity to support increased food production—especially for rice. the country’s staple cereal.

coupled with land degradation in the uplands, improvements in Lao PDR’s rice production systems are urgently needed. Rice production in the country is among the lowest in Asia. In each of the past 5 years, Lao PDR had to import

With a rapidly increasing population

30,000 - 40,000 tons of rice. IRRI, with support from the Swiss

Development Cooperation (SDC), is helping Lao PDR develop its national rice research program. “Because of the scope and intensity of the training effort, the impact on the national research system is enormous,” says Dr. Glenn L. Denning, head of IRRI’s International Programs Management Office.

More than 350 Lao scientists have participated in training at IRRI since

1991 through a special program supported by SDC. The scientists were trained in subjects including integrated pest management, training of trainers, sustainable rice farming systems, gender analysis, and rice germplasm collection and conservation.

A three-year, US$3.54 million grant from SDC will continue the extensive efforts of IRRI and the country to expand rice research to cover all of the significant rice-growing provinces and to increase the number of agricultural researchers and technicians trained in rice production. Training activities will be accelerated inside Lao PDR, at IRRI headquarters, and in other countries, including Thailand.


Philippine-based institutions to take responsibility for international pest management training course Three Philippine-based research and training organizations have agreed to jointly take over an international course on integrated pest management (IPM) originally developed and run by IRRI.

Signatories to the memorandum of agreement are Dr. Santiago Obien, director of the Philippine Rice Research Institute, Dr. Ruben Villareal, chancellor of the University of the Philippines Los Baños, Dr. Percival Sajise, director of the Southeast Asian Regional Center for Graduate Study and Research in Agricul- ture, and Dr. Klaus Lampe, director general of IRRI.

training course that national research partners in Asia have taken up as a regional responsibility since 1992. The others are Rice Production Research, now at the Pathum Thani Rice Research Center, Thailand. and Irrigation and Water Management, at Kasetsart Univer- sity, Thailand. Plans are also under way for the Indian Institute of Technology, Kharagpur, to take over the Engineering for Rice Agriculture Course in 1995.

“These moves are part of IRRI’s strategy to share responsibility for training with selected universities and national, regional, and international organizations that have the capacity to maintain international training standards and sustain training efforts,” says Dr. Ellis Matheny, head of IRRI’s Training Center.

This is the third IRRI-developed group


Announcements Rice dateline

16-20 Jan DOA Sri Lanka-IRRI Project Planning Meeting

18-19 Jan

30 Jan-10 Feb

13 Feb

13-17 Feb 16 Feb

16 Feb

20-21 Feb 16-17 Mar

22-24 Mar

Sri Lanka .......................................................... G. L. Denning, IRRI

IRRI ..................................................................... R. S. Zeigler, IRRI

Waterlogging and Flooding, IRRI ........................ T. L. Setter, IRRI (jointly with Crawford Fund for

International Agricultural Research, Australia)

Annual Rainfed Lowland Rice Program Meeting

Mechanisms of Tolerance of Crops for

Outstanding Young Women in Rice Science

International Rice Research Conference, IRRI ....... R. S. Zeigler, IRRI Upland Rice Research Consortium Steering

Committee Meeting, IRRI ........................................ J.C. Prot, IRRI Rainfed Lowland Rice Research Consortium

Steering Committee Meeting, .............................. R.S. Zeigler, IRRI ICAR India-IRRI Work Plan Meeting, IRRI ........ G. L. Denning, IRRI PhilRice-UPLB-IRRI Work Plan Meeting,

Nueva Ecija, Philippines .................................. G. L. Denning, IRRI AARD Indonesia-IRRI Work Plan Meeting,

Bogor, Indonesia .............................................. G. L. Denning, IRRI

Awarding Ceremony. IRRI .................................... G. Castillo, IRRI

Postdoctoral/project scientist positions at IRRI The International Rice Research Institute (IRRI) is seeking applicants for four postdoctoral/project scientist positions in the following fields:

Biochemistry and molecular biology. Three scientists are needed to work on a major project, funded by the Japanese Government, aimed at increasing rice productivity through improvements in N use efficiency.

A biochemist is required to determine the limiting factors in the uptake and assimilation of ammoniacal N. Familiar- ity with the physiology of plant nutrition is essential and experience in mathemati- cal modeling is desirable. A second biochemist is required to investigate the role of N in regulating Rubisco synthesis and breakdown in the canopy during the ripening phase. Familiarity with enzymatic assays of Rubisco, glutamine synthetase, and GOGAT is essential, and experience with photosynthesis and leaf senescence is desirable. A molecular

biologist is required to develop construct designed to modify N metabolism in roots, leaves, and grain of transgenic rice plants. Familiarity with molecular biology is essential and experience with cereal transformation is desirable. A Ph D is required in each case. Salaries and perquisites of the positions are internationally competitive. The duration of appointments will be for 2 years with the possibility of extension for an additional year.

Please send curriculum vitae, university transcripts, and three letters of reference by 15 Jan 1995 to Dr. John Bennett, Project Leader, Plant Breeding, Genetics, and Biochemistry Div., IRRI. E- mail:IN%”[email protected]”.

Soil science. One scientist is needed to work in a United Nations Development Programme/World Bank-funded research project seeking to improve soil N use efficiency through rice genotype selection and management practices in rice low- lands. The work involves selecting rice germplasm for higher N use efficiency and identifying soil and crop management

practices during the nonrice season that favorably influence biological N 2 fixation

references (with telephone and fax research experience in chemistry and

position is available from 1 Jan 1995. Please send curriculum vitae, date of have a Ph D degree in soil science, soil biology, Soil and Water Div., IRRI. The special reference to N dynamics. and soil N availability. Applicants should numbers) to Dr. J. K. Ladha, Soil Micro- microbiology of lowland soils with

microbiology, or related discipline with availability, names and addresses of three

IRRI group training courses for 1995 IRRI provides a limited number of scholarships for participation in its short- term group training courses for 1995. To be considered for an IRRI-funded scholarship, a scientist must be affiliated with a national institution that has an official collaborative agreement with IRRI in a rice-related research and

training project. A scientist interested in an IRRI-funded scholarship should apply directly to his or her institution and not to IRRI.

IRRI also accepts scientists from other institutions and agencies for the courses if they are working in rice or rice-related areas. Their applications to participate in courses must be endorsed to IRRI by their employer and specify funding sources to cover costs. IRRI’s group

Date Course

23 Jan-3 Mar

20 Mar- 14 Apr 20 Mar-28 Apr

5 Jun-30 Jun 17 Jul-8 Sep

24 Jul-15 Sep 14-25 Aug 14 Aug-3 NOV

2-27 Oct 9 Oct-1 Dec

6 Nov- 15 Dec

13-24 NOV

20 Nov-1 Dec

Irrigation and Water Management a (Kasetsart University,

Hybrid Rice Seed Production Strategic Research in lntegrated Nutrient Management Training on Video Production Integrated Pest Management b (University of the Philippines

Adaptive Research with a Farming Systems Perspective Scientific Programming Genetic Evaluation and Utilization Geographic Information Systems Rice Production Research c (Pathum Thani Rice Research

Engineering for Rice Agriculture d (India Institute of

Gender Perspective and Analysis in Rural Development e

Thailand)

Los Baños)

Center, Thailand)

Technology; Kharagpur, India)

(International Institute for Rural Reconstruction, Silang, Cavite, Philippines)

Frontiers of Social Science Research Methods for Agricultural Systems Analysis

a Kasetsart University, International Irrigation Management Institute (IIMI), and IRRI.

b University of the Philippines Los Baños, Philippine Rice Research Institute, Southeast Asian Regional Center for Graduate Study and Research in Agriculture, and IRRI.

c Thailand Rice Research Institute and IRRI. d India Institute of Technology and IRRI. e International Institute for Rural Reconstruction and IRRI.

course training fee is approximately US$1,200/month; this does not include participants’ roundtrip international airfare, enroute expenses, or shipping allowance upon return home.

The courses are conducted at IRRI headquarters unless otherwise indicated. For additional information, contact the Head, Training Center, IRRI.

International Rice Research Conference 1995 More than 200 rice researchers from around the world will be convening at IRRI during the International Rice Research Conference (IRRC) 1995, 13- 17 Feb, to assess research progress and identify new research approaches and issues for improving the productivity and sustainability of fragile rice-producing ecosystems.

The IRRC, which is held every two to three years, is the world’s premier conference of rice scientists. It provides a venue to encourage international partner- ships addressing research challenges.

Fragile lives in fragile ecosystems: feeding the world’s poor from neglected rice ecosystems is the conference theme.

Scientists will present papers on different subjects under the subthemes of Fragile lives: rural and urban poor in rainfed rice environments; Fragile environments: sustaining productivity for the future: and Opportunities for fragile environments: expanding the resource base.

For information, contact Dr. R. S. Zeigler IRRI Box 933, Manila 1099 Philippines Fax: (63-2) 818-2087 Telex: (ITT)40890 RICE PM E-mail:

IN%”[email protected]”


2nd International Symposium on Systems Approaches for Agricultural Development The second international Symposium on Systems Approaches for Agricultural Development will be held at IRRI on 6-8 Dec 1995. The objectives of the symposium are to review the status of applications of systems research and modeling in agricultural research, with specific focus on countries where agricultural development is facing major challenges, and to promote international collaborative activities and to increase awareness of the opportunities for using systems approaches as a tool in research and planning.

It is organized by IRRI and the International Consortium for Agricultural Systems Applications (ICASA), and the Systems Analysis and Simulation in Rice Production Network (SARP). For details, contact Dr. M. J. Kropff, IRRI.

Graduate certificate in soils With support of the Victorian Education Foundation. the University of Melbourne, in collaboration with La Trobe Univer- sity, is offering two graduate courses in soil science. The graduate certificate in soil management is a one-semester course intended for graduates in science, applied science, geography and related disciplines or for people with equivalent qualifications and experience who have little or no formal training in soil science. The two-semester graduate diploma in soil science is intended for graduates in agricultural or forest science or for people with equivalent qualifications and experience who wish to study aspects of soil science in greater depth.

For more information, contact Profes- sor R. E. White, Faculty of Agriculture and Forestry, University of Melbourne, Parkville, Victoria 3052, Australia. Tel: (03) 344 4642


New IRRI publications Program report 1993. 1994. 317 pages. US$48.00 in highly developed countries (HDC), US$13.00 in less developed countries (LDC), plus US$8.00 airmail or US$12.00 surface postage.

The IRRI program report for 1993 is the definitive record of achievement in research undertaken by IRRI, much of it in collaboration with others. It is intended to account to donors and to make available to rice researchers worldwide current information about the outcome of the activities projected in the Institute’s work plan for 1990-94.

The report includes brief summaries of research undertaken by the Institute during the year, plus discussions of the international programs that interconnect with the research programs. It continues to be the primary, definitive record of the progress made by the Institute.

IRRI 1993-1994: Filling the world’s rice bowl. 1994. 96 pages. US$18.00 in HDC, US$5.00 in LDC, plus US$6.00 airmail or US$1.50 surface postage.

IRRI’s new corporate report goes beyond just reporting the accomplishments of the Institute over this period. It also looks ahead to the year 2025. The world population then will be about 8.3 billion people, of whom 4.3 billion will be rice consumers.

Filling the world’s rice bowl today and into the future presents an enormous challenge to IRRl and its collaborators. Researchers must find a way to increase rice production by 70 percent over the next 30 years.

was able, before the beginning of its new 1994-98 work plan, to start with confi- dence some of the new and very exciting programs that will help keep supply and demand for rice in 2025 in balance, while sustaining the world’s natural resources base. The report addresses these important issues.

Biology and management of rice insects. 1994. 779 pages, US$50.00 in HDC, US$13.00 in LDC, plus US$26.00 airmail or US$2.50 surface postage.

Building on past achievements, IRRI

Insect pests are severe constraints to rice production throughout the world. Evi- dence indicates that the severity and frequency of attack have increased in recent years.

accepted as the rational approach to the regulation of rice insect populations, since it is economically attractive and ecologically and socially acceptable.

Success in the development and implementation of effective rice insect management programs has been limited in scope and has yet to be even partially achieved in many of the rice-growing areas of the world. The authors have written this book to provide the basic information needed for successful management of a rice pest program.

Hybrid rice technology: new develop- ments and future prospects. 1994. 296 pages. US$21.00 in HDC, US$5.00 in LDC, plus US$6.00 surface postage.

Successful development and use of hybrid rice in China during the past two decades have demonstrated that yield potential can be increased by commercial exploitation of heterosis or hybrid vigor in this self-pollinated crop. Scientists at IRRI and in national rice research programs are exploring the potential of this biological phenomenon to raise rice varietal yields. Results are encouraging and some national programs (India and Vietnam) have recently released hybrid rice for commercial cultivation.

A symposium was held at IRRI in 1992 as a follow-up to the one held in 1986. Eighty scientists and seed production experts from 18 countries, IRRI, and FAO attended. Contributions covered breeding, biotechnology, seed production, agronomy, plant physiology, plant pathology, entomology, and economics. Fourteen country reports and three reports on international collaboration on hybrid rice were also presented by representatives of FAO, IRRI, and China. This book is expected to be a valuable source of information on hybrid rice for the coming years.

Integrated pest management has been

Cornell University grants Cornell University, USA, is sponsoring fellowships in environmental research in international agriculture. They are intended to encourage creative and imaginative research aimed at integrating environmental and natural resource protection with mainline international agriculture research and development. Qualified disciplines include ecology, botany, zoology, resource management, wildlife protection, climatology, entomology, atmospheric sciences, microbiology, and other environment-oriented fields. The program provides a stipend and research support for visiting scientists at international agricultural research centers. Funding is shared between the Rockefeller Foundation and the host institution.

There is no formal deadline for applications, but it is strongly urged that they be submitted at least six months before the requested starting date. Applications should include a written project developed and submitted jointly by the candidate and the host center; curriculum vitae and copies of recent and relevant publications; a letter from the host center’s administration recommend- ing the candidate and the host center; and two letters of recommendation from established scientists familiar with the applicant’s qualifications.

Centers in Colombia, India, Mexico, Nigeria, Peru, Philippines, and Taiwan, China are participating in the program, but others will be considered. For more information, contact Ms. Lyn Hogan, Communications Officer, The Rocke- feller Foundation, 1133 Avenue of the Americas, New York NY 10036, USA. Tel: (212) 869 8500

New publication Feeding and greening the world. Dr. Derek Tribe. Published by CABI. Order from The Crawford Fund for International Agricultural Research, GPO Box 309 Canberra ACT 2601 Australia. Fax: (06) 2486016.

Dr. H. P. Moon receives Daesan Prize Dr. Huhn Pal Moon, plant breeder and director, Rice Breeding Division, Crop Experiment Station, Suweon, Korea, has been awarded the 1994 Daesan Prize. The prize was given in recognition of the significant contribution of Dr. Moon and his research team in the development of new rice varieties in Korea. Their efforts prevented a rice shortage in the country and reduced breeding time from 10-12 years to 5-6 years.

Dr. Moon is associated with IRRI as senior scientist in the Korea-IRRI Project, as national coordinator of the International Network for Genetic Evaluation of Rice (INGER) for Korea, and as a member of the INGER Advisory Committee.

Call for news Individuals, institutions, and organizations are invited to tell readers about upcoming events in rice research or related fields in the Rice dateline. Send announcements to the Editor. Interna- tional Rice Research Notes, IRRI.

IRRI address International Rice Research Institute P.O. Box 933 1099 Manila, Philippines Tel: (63-2) 818-1926 Fax: (63-2) 818-2087 Telex: (ITT) 40890 RICE PM E-mail: IN% [email protected]”

Rice literature update reprint service Photocopies of items listed in the Rice literature update are available from the IRRI Library and Documentation Serv- ice. Reprints of original documents (not to exceed 40 pages) are supplied free to scientists of developing countries. Rice scientists elsewhere are charged US$0.20 for each page or part of a page copied, plus postage. Make checks or money orders payable to Library and Documen- tation Service, IRRI.

Address request to Library and Documentation Service, IRRI. E-mail: IN%”[email protected]”


•

Instructions for contributors

NOTES

General criteria. Scientific notes submitted to the IRRN for possible publication should • be original work, • have international or pan- national relevance, • be conducted during the immediate past three years or be work in progress, • have rice environment relevance, • advance rice knowledge, • use appropriate research design and data collection methodology, • report pertinent, adequate data, • apply appropriate statistical analysis, and • reach supportable conclu- sions.

Routine research. Reports of screening trials of varieties, fertillzer, cropping methods, and other routine observations

using standard methodologies to establish local recommendations are not ordinarily accepted Examples are single- season, single-trial field experiments. Field trials should be repeated across more than one season, in multiple seasons, or in more than one location as appropriate. All experiments should Include replications and an Internation- ally known check or control treatment.

Multiple submissions. Normally, only one report for a single experiment will be accepted Two or more items about the same work submitted at the same time will be returned for merging. Submit- ting at different times multiple notes from the same experiment is highly inappropriate, Detection will result in the rejection of all submissions on that research.

IRRN categories. Specify the category in which the note being submitted should appear. Write the category in the upper right-hand corner of the first page of the note.

GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality pest resistance

diseases insects other pests

stress tolerance drought excess water adverse temperature adverse soils other stresses

ment irrigated rainfed lowland

flood-prone (deepwater and tidal wetlands)

seed technology

CROP AND RESOURCE MANAGEMENT

soils soil microbiology physiology and plant nutrition fertilizer management

inorganic sources organic sources

crop management integrated pest management

insects weeds other pests

water management farming systems farm machinery postharvest technology economic analysis

ENVIRONMENT SOCIOECONOMIC IMPACT EDUCATION AND COMMUNI-

integrated germplasm improve-

upland

diseases

CATION RESEARCH METHODOLOGY

Manuscript preparation. Arrange the note as a brief statement of research objectives, a short description of project design, and a succinct discussion of results. Relate results to the objectives. Do not Include abstracts. Do not cite references or include a bibliog- raphy. Restrain acknowledg- ments.

Manuscripts must be in English. Limit each note to no more than two pages of double- spaced typewritten text. Submit the original manuscript and a duplicate, each with a clear copy of all tables and figures. Authors should retain a copy of the note and of all tables and figures.

Apply these rules, as appropriate, in the note: • Specify the rice production ecosystems as irrigated, rainfed lowland, upland, deepwater, and tidal wetlands. • lndicate the type of rice culture (transplanted, wet seeded, dry seeded) • If local terms for seasons are used, define them by characteristic weather (wet season, dry season, monsoon) and by months. • Use standard, internationally recognized terms to describe rice plant parts, growth stages, and management practices. Do not use local names. • Provide genetic background for new varieties or breeding lines. • For soil nutrient studies, include a standard soil profile description, classification, and relevant soil properties. • Provide scientific names for diseases. insects, weeds, and crop plants. Do not use common names or local names alone. • Quantify survey data, such as infection percentage, degree of severity, and sampling base. • When evaluating susceptibility, resistance, and tolerance, report the actual quantification

of damage due to stress, which was used to assess level or incidence. Specify the measurements used. • Use generic names, not trade names, for all chemicals. • Use international measurements. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) for small-scale studies. • Express all economic data in terms of the US$. Do not use local monetary units. Economic Information should be presented at the exchange rate US$:local currency at the time data were collected. • When using acronyms or abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Use the abbreviation thereafter. • Define any nonstandard abbreviations or symbols used in tables or figures in a footnote, caption, or legend.

Tables and figures. Each note can have no more than two tables and/or figures (graphs, illustrations, or photos). All tables and figures must be referred to in the text; they should be grouped at the end of the note, each on a separate page Tables and figures must have clear titles that adequately explain the contents.

Review of notes. The IRRN editor will send an acknowledg- ment card when a note is received. An IRRI scientist, selected by the editor, reviews each note. Reviewer names are not disclosed. Depending on the reviewer's report, a note will be accepted for publication, rejected, or returned to the author(s) for revision.

(continued on back cover)

Documents

International Rice Research Notes Vol.19 No.4