International Rice Research Notes Vol. 16 No.4

7/30/2019 International Rice Research Notes Vol. 16 No.4

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IRRN GUIDELINES

The International Rice Research

Newsletter objective is:

"To expedite communication

among scientists concerned with

the development of improved

technology for rice and for rice-

based cropping systems. Thispublication will report what

scientists are doing to increase the

production of rice, inasmuch as

this crop feeds the most densely

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current research findings."

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guidelines, and research categories

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suggestions, please write the editor,

IRRN, IRRI, P.O. Box 933, Manila,

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has international, or pan-national,

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reports appropriate, adequate data

applies appropriate analysis, using

appropriate statistical techniquesreaches supportable conclusions

Please examine the criteria,

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relevance

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The International Rice Research

Newsletter is a compilation of brief

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experiments should include

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Limit each report to two pages of

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analysis.

environment (irrigated, rainfed

lowland, upland, deepwater, tidal

wetlands).

Report appropriate statistical

Specify the rice production

Specify the type of rice culture

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seeded).

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abbreviations, write the name in

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Define any nonstandard abbrevia-tions or symbols used in a table orgraph in a footnote or caption/

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Provide scientific names for

When using acronyms or

Categories of research published

GERMPLASM IMPROVEMENTgenetic resources

genetics

breeding methods

yield potentialgrain quality

pest resistance

diseases

insects

other pests

stress tolerance

drought

excess water

adverse temperature

adverse soils

irrigated

rainfed lowland

upland

deepwater

tidal wetlands

seed technology

CROP AND RESOURCEMANAGEMENTsoils

soil microbiology

physiology and plant nutrition

fertilizer management

inorganic sources

organic sources

integrated germplasm improvemen

crop management

integrated pest management

diseases

insects

weeds

other pests

water management

farming systemsfarm machinery

postharvest technology

economic analysis

ENVIRONMENT

SOCIOECONOMIC IMPACT

EDUCATION ANDCOMMUNICATION

RESEARCH METHODOLOGY


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CONTENTS

GERMPLASM IMPROVEMENT

Genetics

5 Contribution of IR crosses to improved cultivars for irrigated rice in Latin

America

Breeding methodhybrid rice5 Photosynthesis and respiration in rice hybrids

6 Effect of low light on F1 rice hybrids

6 Analysis of heterotic relationships among quantitative characters of hybrid

7 Restorers and maintainers for two cytoplasmic male sterile lines

7 Heterosis in physiological attributes of rice hybrids

8 Meiotic behavior of some WA cytosterile lines

9 Maintainers and restorers for WA cytoplasmic source (V20 A)

9 New CMS line Zaoxian A with incomplete dominance of short duration

10 Natural outcrossing on two cytoplasmic male sterile lines in northern India

Yield potential

10 Screening rice varieties and breeding lines for internode elongation ability

12 Elongation ability in deepwater rices

Pest resistancediseases

12 Utilization of sources of resistance to bacterial blight (BB) in China

13 Resistance to tungro in some wild relatives of rice

13 Distribution of rice varieties resistant to bacterial blight (BB) in Yunnan,

14 Presence of rice tungro bacilliform virus (RTBV) in xylem cells of tungro-

rice

under field conditions

China

infected rice

Integrated germplasm improvementup1and

14 Four rice varieties released in Sierra Leone

Integrated germplasm improvementirrigated

15 ASD18, a blast (B1)-resistant rice variety for Tamil Nadu

Integrated germplasm improvementrainfed lowland

15 Three new varieties of short-duration rice released in Cambodia

Integrated germplasm improvementtidal wetland

16 Performance of short-duration rice varieties in tidal swamps of Indonesia

CROP AND RESOURCE MANAGEMENT

Fertilizer management

17 Influence of organic and inorganic amendments, modified urea, and

application methods on ammonia volatilization in saturated calcareous soi

Fertilizer managementorganic sources18 Effect of gypsum-enriched biogas sludge and farmyard manure on ric

yield

Fertilizer managementinorganic sources

18 Effect of irrigation and nitrogen on transplanted summer rice yield and

19 Improving applied phosphorus utilization by rice in Madagascar

Integrated pest managementdiseases

19 Association ofFusarium moniliforme Sheld. with rice seeds and subsequen

20 Effect of grain discoloration in upland rice on some yield components

Integrated pest managementinsects

20 Duration of diapause in white stem borer (SB) Scirpophoga innotata21 Morphometric measurements of green leafhopper (GLH) Nephotetti

21 A new blister mite pest of rice in the Philippines

22 A quadrat insect sampler for direct seeded rice

Farming systemsdeepwater rice

22 Cropping patterns for deepwater rice environments

Farming systemsirrigated rice

23 Transplanted rice-based cropping sequences in an irrigation canal command

23 Rice-based cropping systems for Andhra Pradesh

ANNOUNCEMENT

24 Tropical crops symposium postponed one year

water use efficiency

infection in Pakistan

nigropictus (Stl) head and body during development

area of Rajasthan


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Heterosis in photosynthesis in F1 rice

hybrids is not well established; it is

considered to be mostly cross-specific.

We studied heterosis in photosynthetic

rate (Pn) and maintenance respiration

LMR) in IR54152 A/IR54 and V20 A/

IR36 at the vegetative (35 d after plant-

ing) and flowering stages during the 1990

dry season. MR provides energy for the

biochemical and physiological state of

established tissues. It differs considerablyamong cultivars.

The hybrids, their restorers, and check

variety Swarnaprabha were planted in

pots. Pn in the second leaf at the vegeta-

tive stage and in the flag leaf at flowering

were measured by LI-6000 at full sunlight

(about 1200 E/m2per s). MR was

measured by differential respirometer as

CO2 evolution rate on excised leaves after

incubation in the dark for 8 h.

The hybrids showed higher Pn and

MR than their restorers at both growth

stages (see table). Pn was similar, but MR

was higher in the hybrid with IR36 thanin the hybrid with IR54. Both hybrids had

higher Pn and MR than Swarnaprabha.

Heterosis over restorer was consis-

tently higher in V20 A/IR36. Heterosis

for Pn was higher at the vegetative stage

than at flowering; differences in heterosis

for MR were only marginal. Standard

K. S. Murty and S. K. Dey, Central Rice

Research Institute, Cuttack 753006, India

Photosynthesis andrespiration in rice hybrids

GERMPLASM IMPROVEMENTGenetics

Contribution of IR crosses toimproved cultivars forirrigated rice in Latin

America

Federico Cuevas-Prez, IRRI liaison

scientist for Latin America, Apartado

Areo 6713, Cali, Colombia

Adoption of modern semidwarf rice

varieties in Latin America began in the

late 1960s with the introduction of IR8.

Although yield gains were impressive,

grain quality was below regional stan-

dards. This stimulated additional intro-

ductions and breeding work to select

locally adapted materials.After nearly 20 yr of germplasm

improvement work, modern semidwarf

varieties are planted on 31 % of the rice

area and contribute 56% of total Latin

American rice production. For irrigated

rice, 80% of the area and production are

modern varieties. International collabora-

tion through the International Network

for the Genetic Evaluation of Rice

(INGER, formerly IRTP) has been a

major force behind these technological

improvements.

To determine the contribution of IR

materials to the improvement of irrigated

rice in Latin America, the pedigrees of

143 cultivars released 1971-89 were ana-

lyzed: 85% had at least one IR line in

their parentage.

Chile was the only country with no

cultivar showing IR parentage, probably

because of subtropical growing condi-

tions. Other countries whose materialshad low IR input were the traditional

exporters, Surinam and Uruguay.

Table 1. IR breeding lines in the parentage of

irrigated rice cultivars released in Latin America,1971-89.

IR line Cultivar name Country, year of

release

IR442 Huallaga Peru, 1972

BR2 Brazil, 1978

IR579 IR100

INIAP2

Nicaragua, 1973

Ecuador, 197 I

Navolato A7 1 Mexico, 197 I

Brazil, 1976IR665 IR665

IR822 CR1113 Costa Rica, 1974

IR837 Bamoa A75 Mexico, 1975

IR841 IR841

Piedras Negras A74 Mexico, 1974

Brazil, 1974

EMPASC 104 Brazil, 1985

IR930 BR-IRGA 408 Brazil, 1975

Chancay Peru, 1972

Cica 4

INIAP6

Colombia, 1971

Ecuador, 1972

Naylamp Peru, 1971

IR1055 N

IR1529 IR1529

Guyana, 1975

Cuba, 1978IR2058 Pesagro 102 Brazil, 1983

IR2153 Juma 62 Dominican Republic,

1986

IR4570 PA-3 Peru, 1984

IR5853 Saavedra Bolivia, 1987

IR8208 Pesagro 101

IR18348 INIAP11

Brazil, 1983

Ecuador, 1989

In rice varieties from the rest of the

region, 24 cultivars were direct selections

of IR lines (Table 1). About two-thirds of

them were released 1971-78. IR930 was

named in five countries. Navolato A71

(IR579) in Mexico and INIAP II (IR1834in Ecuador are the most widely grown

direct IR selections. Since 1978, most of

the IR line contributions have been as

parents in local crosses.

Fifty-two IR lines have been used in

national breeding programs; the most

frequently found were IR8, IR579, and

IR930 (Table 2). Some 90% of the 2.1

million ha of irrigated favorable rainfed

rice area of Latin America is currently

planted to cultivars with IR8 in their

parentage.

Table 2. IR lines most frequently found in the

parentage of Latin American irrigated rice culti-vars, 1971-89.

Progenitor Genetic contribution perIR line of released cultivara

cultivars

Mean Maximum

IR8 76.2 0.36 0.75IR262 26.6 0.50 0.50IR579 36.4 0.29 1.001R661 9.1 0.22 0.50IR665 34.3 0.28 1.00IR84I 16.8 0.17 1.00IR930 51.0 0.38 1.00

aAssuming 50% contribution of each parent in a single cross.

A contribution of 1.0 indicates that the IR line was released as

a cultivar.

Breeding methodshybrid rice

IRRN 16:4 (August 1991) 5


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heterosis was also high in V20 A/IR36, standard heterosis over Swarnaprabha in Analysis of heteroticespecially for MR at flowering. Pn/MR, especially at flowering. relationships among

marginal positive heterosis at the restorers to reduce MR and improve Pn hybrid ricevegetative stage and was negative at and Pn/MR would increase photosyn-

flowering. Both hybrids showed negative thetic productivity.

Pn/MR in IR54752 A/IR54 showed These results suggest that selecting quantitative characters of

Peng Junhua and Tian Shoujun, Crop

Photosynthetic rate (Pn) and maintenance respiration (MR) a of F1 rice hybrids in Cuttack, India, 1990 dry

season.b tural Sciences, Chengdu 610066,

Institute, Sichuan Academy of Agricul-

Sichuan, ChinaVegetative Flowering

Hybrid

Pn MR Pn/MR Pn MR Pn/MR In 1987, we used 6 male sterile lines and

IR54752 A/IR54 45.3 1.66 27.2 33.4

(24) (17) (6) (6) (19)1.23

V20 A/IR36 46.1 1.80 25.6 34.7 1.46 23.7 Apr-Oct 1988 was laid out in a random-(11)

(36) (25) (9) (26) (23) (2) ized complete block design with threeSwarnaprabha 36.2 1.28 28.3 29.6 0.90

3.4 0.11 1.9 0.12Standard heterosis and hill spacing was 17 23 cm. The

12 fertility restorer lines to make 72 F127.1 hybrid combinations. A field experiment

LSD (0.05)32.8 replications, with 30 plants per plot. Row

IR54752 A/IR54 25 29V20 A/IR36 27 40

4-10

13 3617 62

-17 center five plants in each plot were

-28 sampled.aPn and MR in mg CO2/dm

2per h.

bFigures in parentheses = heterosis over restorer.

Effect of low light on F1 rice Effect of low light (50% of normal) from 40 dafterplanting to harvest on dry matter and yield of F1rice hybrid restorers and check varieties. Cuttack,

India.

hybrids

K. S. Murty and S. K. Dey, Central Rice Total dry Yield

Research Institute, Cuttack 753006, lndia Cultivar matter (g/m2) (g/m2)

F1 rice hybrids are reported to be more

productive than elite conventional Hybrid

Full Low Full Lowlight light light light

varieties even under such stresses as

drought and salinity. Low light is another

major constraint to rice production during

the rainy season.

We studied tolerance for low light inhybrids IR54752 A/IR54 and V20 A/IR36

and their restorers, with standard checks

Ratna and Swarnaprabha during 1990 dry

season. The crop was grown in 1.2-m2

field plots at 15- 10-cm plant spacing

and fertilized with 80 kg N/ha.

imposed from 40 d after planting to

harvest by shading with wood screens.

Controls were maintained under normal

sunlight (about 420 cal/cm2 per d). The

experiment was laid out in a randomized

complete block design with three replica-tions. Growth durations were 128 d in all

treatments.

Low light (50% sunlight) condition was

The hybrids showed positive heterosis

in total dry matter and yield over the

restorer parent under low light only (see

table).

Yield and heterosis in yield were higher

for IR54752 A/IR54 than for V20 A/IR36.

IR54752 A/IR54 985 643 418 206V20 A/IR36 853 471 345 167

RestorersIR54 993IR36 853

ChecksRatna 803Swarnaprabha 928

Mean 902

LSD (0.05)VarietyTreatmentVariety treatment

Heterosis over restorerIR54752 A/IR54 1V20 A/IR36 0

Standard heterosisIR54152 A/IR54 vs

Ratna 22Swarnaprabha 6

Ratna 6Swarnaprabha 8

V20 A/IR36 vs

537 426 179427 400 164

358 354 144

597 480 243

506 403 183

99 1757 44ns ns

19 2 1511 13 2

79 18 43

8 13 15

33 3 1620 28 31

This could be associated with the higher

yield potential of restorer IR54. The

hybrids also showed strong standard

heterosis over Ratna under low light, but

negative heterosis in yield over Swar-

naprabha, a low light-tolerant variety.

Eleven characters were analyzed

(Table 1): days to heading (DH), culm

number/plant (CN), panicle length (PL,cm), plant height (PH, cm), total spikelet

number/panicle (TSN), filled spikelet

number/panicle (FSN), filled spikelet

percentage (FSP), 1,000-grain weight

(GW, g), biological yield/plant (BY, g),

grain-straw ratio (GSR), and grain yield/

plant (GY, 8). Heterosis was estimated

for each character as

H = F1 - (P1 + P2)/2

Correlation coefficient and stepwise

regression analysis were used to estimate

relationships among characters.Correlations vaned with character

combinations; 31 were significant (Table

1). In the F1 hybrids, correlations of DH

to TSN and FSN; CN to BY; PL to PH,

FSN, GW, and BY; PH to TSN, FSN,

and BY; TSN to FSN and BY, FSN to

FSP, BY, and GSR; FSP to GSR; GW to

GSR; and CY to CN, PL, PH, FSN, FSP,

GW, BY, and GSR were positive and

significant; those of DH to GW, CN to

TSN and FSN, and TSN to FSP, GW,

and GSR were negative and significant.

Some of the character combinationshad more or less the same correlation

trends, except that more character

combinations showed significant correla-

tions in the F1 hybrids than in the parents,

particularly GSR, which had negative

correlation (although nonsignificant) in

the parents with PL, FSN, FSP, GW, and

BY but showed positive correlation

6 IRRN 16:4 (August 1991)


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Restorers and maintainersfor two cytoplasmic malesterile lines

J. S. Bijral, T. R. Sharma, B. B. Gupta,

K. Singh, and C. L. Raina, SKUAST,

Regional Agricultural Research Station

(RARS), R.S. Pura 181102, India

coefficient in the hybrids. It should be

possible to increase GSR and BY simulta-

neously in hybrids, but not in parents.

The multiple regression equation for

GY heterosis was GY= 4.609 + 0.100 DH

+ 1.039 CN+ 0.068 FSN+ 0.429 GW

+ 0.312BY+ 27.286 GSR. This model

was effective in predicting GY heterosis,

accounting for 88% of the total variation

(Table 2). Except for DH, the effect of the

regression was highly significant.

Biological yield was the most important

contributing character in the formation of

GY heterosis.

Heterosis of GY depends on heteroses

of BY, FSN, CN, PH, PL, FSP, GW, and

GSR. It would be helpful in hybrid rice

breeding to take into account the

heterotic relationships among some

metrical characters.

Table 1. Correlation coefficients for heterosis of F1 and parents among 11 characters.a

Trait DH CN PL PH TSN FSN FSP GW BY GSR GY

DH P 1 .20 .06 .14 .37** .42** .22 .35** .14 .19 .13F1 1

CN P 0.2 1F1 .38** 1

.08 .08 .30* .24* .04 .09 .59** .10 .50**

PL P .78** .10 1F1 .43** .27* 1

.65** .22 .40** .11 .23* .33** .19 .39**

PH P .81** .02 .92** 1F1 .57** .20 .74** 1

.47** .49** .07 .10 .43** .08 .41**

TSN P .49* .37 .48* .52* 1 .72** .30** .27* .34** .25* .23F1 .55** .61** .34** .41** 1

FSN P .76** .38 .76** .69** .68** 1F1 .57** .60** .58** .44** .84** 1

.39** .03 .49** .29* .57**

FSP P .44* .14 .39 .23 .20 .57* 1F1 .30** .28* .59** .26* .15 .65** 1

.17 .12 .75** .38**

.21 .27* .31**

.04 .86**

GW P .18 .34 .25 .31 .16 .12 .26 1

BY P .85** .18 .81** .84** .32 .68** .48* .37 1F1 .47** .14 .53** .53** .32** .52** .49** .43** 1

F1 .44** .11 .08 .26** .25** .11 .53** .15 .02 1

GY P .81** .19 .77** .80** .28 .71** .56* .36 .98** .48 1F1 .40** .14 .54** .44** .23* .54** .65** .46** .91** .29 1

aCorrelation coefficients for parents (P) and F1 below the diagonal, those for heterosis above the diagonal. *,** = significant at

5 and 1% levels, respectively.

F1 .14 .11 .32** .27* .21 .01 .30** 1

GSR P .61** .23 .53* .58** .35 .36 .08 .02 .56* 1 .29*

Table 2. Statistical test for the model of grain yield heterosis.a

SV DF SS @ MS F R2

DH 1 5.503 6 5.503 2.66CN 1 21.734 3 21.734 10.49**FSN 1 18.942 4 18.942 9.14**GW 1 16.097 5 16.097 7.77**BY 1 47.109 1 47.109 22.73**GSR 1 37.017 2 37.017 17.86**

Error 65 134.722 2.073Total 71 1111.090

Multiple regression 6 976.366 162.728 78.51** 0.8787

a @ = magnitude order of SS, ** = significant at the 1% level.

In a hybrid rice breeding program based

on a cytoplasmic male sterility and

fertility restoration system, identification

of effective maintainers and restorers is of

great importance. We crossed 10 short-,

medium-, and long-duration rice cultivars

with cytoplasmic male sterile lines Zhen

Shan 97 A and V20 A in 1988 wet season

at Ranbir Singh Pura, Jammu, and

Kashmir. The F1 hybrids were evaluated

for spikelet fertility during the 1989 wet

season.

Varieties showing more than 80%

spikelet fertility were classified as

restorers; those with 30-79%, 1-29%, and

less than 1% spikelet fertility were rated

as partial restorers, partial maintainers,

and effective maintainers, respectively.All test cultivars except Dular,

IET10770, and N22 were identified as

restorers (see table). N22 partially

restored the fertility of both cytosterile

lines. IET10770 and Dular were classi-

fied as effective maintainers.

Restorers and maintainers for 2 cytoplasmic malesterile lines identified at RARS, R.S. Pura, India,1989 wet season.a

Spikelet fertilityVariety

Zhen Shan 97 A V20 A

IR35454-18-1-2-2 R RIR25912-30-2-3-2 R RIR29692-99-2 R RIR9761-19-1-R R RB4227 E-KN-10 R RIET10321 R RIET10770 M MIET1410 R RDular M M

N22 PR PR

a R = restorer (80% spikelet fertility), PR =partial restorer (30-

79% spikelet fertility, PM = partial maintainer (l-29% spikelet

fertility), M = maintainer (less than 1% spikelet fertility).

Heterosis in physiologicalattributes of rice hybrids

K. S. Murty, S. K. Dey, and P. J. Jachuck,

Central Rice Research Institute, Cuttack

753006, India

Heterosis in yield characters of F1 rice

hybrids from cytoplasmic genetic male

sterile (CMS) lines has been well

recognized. Information on the heterosis

of physiological characters, however, ismeager.

We studied standard heterosis over

check Jaya of seven F1 hybrids (six from

CMS line IR54752 A and one from

Madhu A) during 1989 wet season (Jul-

Oct). The hybrids and Jaya were trans-

planted (25 d after seeding) at 20-

15-cm spacing, one seedling/hill, in a



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randomized block design with three

replications. Fertilizer (80 kg N/ha) was

applied in 3 equal splits: at transplanting,

20 d after transplanting, and at panicle

initiation.

4.5 h of bright light/d. Periodic samples

were taken for leaf area index (LAI), total

dry matter (TDM), and crop growth rate

(CGR). Photosynthetic rates (Pn) of thesecond leaf before flowering and the flag

leaf at flowering were measured with LI-

6000 Portable Photosynthesis System;

maintenance respiration (MR) was

measured by Gilson differential respi-

rometer. Crop photosynthesis is assumed

to be Pn LAI.

The season was cloudy, with less than

Yield and yield attributes were

recorded at harvest. Given a high

frequency of sterile plants in the hybrids,

20 normal fertile plants were taken for

yield assessment. Standard heterosis was

calculated over check Jaya.Considerable standard heterosis was

apparent in Pn, LAI, and Pn LAI at

30 d after planting and in post-flowering

CGR, TDM, and yield (see table).

Heterosis of MR was negative. Panicle

number and grain number/m2 exhibited

high heterosis. The hybrid with Madhu A

showed good heterosis in Pn, MR, and

Pn/MR at flowering (F).

Swarna and IR54 hybrids combined

Among the hybrids with IR54752 A,

Meiotic behavior of some WAcytosterile lines

R. K. Mandal and S. Saran, Botany

Department, Patna University, Patna

800005; and V. N. Sahai, A.R.I. Mithapur

farm, Patna I, India

The meiotic behavior of CMS lines

IR46827 A, IR46828 A, IR46829 A, and

IR46830 A was studied to ascertain

chromosomal abnormality associatedwith pollen abortion or sterility.

Meiosis of microsporogenesis showed

12 regular, well-developed bivalents at

diakinesis and metaphase I with a normal

12: 12 separation of chromosomes at

anaphase I; 3 secondary associations of 2

bivalents each in a large number of

8 IRRN 16:4 (August 1991)

Standard heterosis for physiological characters and yield of rice hybrids, Cuttack, India, 1989 wet season

Standard heterosis (%) of hybrids over

Charactera Standard IR54752 A Jaya

check

Jaya IR54 IR54 IR27- Prabhat Swarna Pratiba Madhu A(UAS) (CRRI) 31.5 IR1532

Pn at 30 d (mg CO2/ 28.1 22 8 20 12 8 9 17

dm2per h)

Flowering 34.6 4 5 11 11 14 4 23

MR at flowering 2.6 9 4 14 7 14 14 12Pn/MR at flowering 8.9 0 3 0 17 7 4 18

Pn LAI (F) gCO2/m2 11.3 35 22 11 2 3 13 19

LAI at 30 d 0.92 39 31 4 19 42 6 3

Flowering 3.28 42 16 25 9 20 9 4

SLW at flowering 520 8 11 12 2 4 18 14

(mg/dm2)Flag leaf area (cm2) 29.3 22 19 17 11 26 14 4

FL SLW (mg/dm2) 541 2 7 5 8 3 9

TDM at 30 d (g/m2) 88 30 39 2 4 22 9

9

870

2

Flowering 23 11 40 16 40 14 26

Harvest 1051 60 62 66 26 54 28 13

CGR at 0-30 d 2.93 30 39 2 4 24 9 2

(g/m2per d)50 d tooflowering 14.7 15 3 15 48 6 10 8

Flowering-harvest 6.0 243 311 190 226 123 96 203

Yield (g/m2) 384 68 73 77 2 71 17 7

Yield (g/m2

per d) 2.9 59 62 59 0 55 7 14Panicles/m2 177 53 52 52 33 33 28 23

Grains/panicle (no.) 87.7 3 4 9 21 45 16 7

Grains/m2 (102) 155 56 45 65 4 94 7 25

1000-grain wt (g) 26.3 4 7 6 0 11 7 22

HI (%) 36 6 8 8 17 11 8 4

aPn = photosynthetic rate, MR = maintenance respiration rate, LAI = leaf area index, TDM = total dry matter, CGR = crop growt

rate, SLW = specific leaf wt, FL SLW = flag leaf specific leaf wt

strong heterosis in LAI, TDM, and yield, hybrids might be improved by combining

but heterosis in Pn at flowering and CGR them with photosynthetically effective

at reproductive growth was poor. restorers.

Heterosis for photosynthesis in these

Meiotic behavior of chromosomes in 4 CMS lines.

Pollen

CMS line mother cell Diakinesis Metaphase Anaphase Remarks

scored (no.) I I

IR46827 A 50 12 II 12 II 12:12

Chromatin becomes feeb

in anaphase I and dis-

IR46828 A 50 12 II 12 II 12:12 integrates completely in

IR46829 A 50 12 II 12 II 12:12 telophase I.

IR46830 A 50 12 II 12 II 12:12

preparations; a variable number and type. In this type, meiosis initiallybehavior of nucleoli; and a gradual progresses normally, but the microspores

disintegration of chromatin setting in at tend to abort. Total absence of chromatin

anaphase I, resulting in its complete dis- matter at telophase I is a new report of a

appearance by late telophase I (see table). cytological basis for pollen abortion in

Complete sterility of microspores in CMS lines. Imbalance of synthesis and

all CMS lines showed that they belonged degradation of auxins could be the reaso

to the CPA (complete pollen abortion) for pollen abortion and complete sterility


10/26

Maintainers and restorersfor WA cytoplasmic source(V20 A)

S. B. Pradhan and P. J. Jachuck, Cetral

Rice Research Institute (CRRI), Cuttack

753006, Orissa, India

Screening locally adapted elite breeding

lines for genetically diverse maintainers

and restorers for different cytoplasmic

male sterile (CMS) lines is important in

developing new CMS lines.

We used 37 National Screening

Nursery entries as pollen parents for

crossing with stable WA-type CMS line

V20 A. The F1 hybrids were grown in a

well-puddled field. During anthesis,

anthers from 10-15 spikelets each of 3

panicles of individual F1plants were

collected at random. They were examined

under a microscope, using Lugols iodinesolution, and pollen sterility estimated.

Spikelet fertility was estimated on two to

three panicles that had been bagged on

each hybrid plant.

Varieties were classified as effective

maintainers (spikelet fertility less than

l%), weak maintainers (spikelet fertility

less than 25%), partial restorers (spikelet

fertility 25-79%), and effective restorers

(spikelet fertility more than 80%).

IET10158, IET10428, IET10849,

IET10851, IET11721, IET11811,

IET11668, and IET10503 were effectivemaintainers; IET10830, IET9819,

IET10458, IET9979, IET9798,

IET11O57, IET10462, IET10463,

IET10435, and IET11722 were effective

restorers for V20 A (see table). The

effective maintainers will be used to

develop new CMS lines possessing WA

cytoplasm with different nuclear back-

grounds, using recurrent backcrossing

procedures.

New CMS line Zaoxian A withincomplete dominance ofshort duration

Liu Biaoxi, Peng Junhua, and He

Yuezhong, Crop Institute, Sichuan

Academy of Agricultural Sciences,

Chengdu 610066, China

Fertility restoration of National Screening Nursery varieties in test crosses with V20 A of wild abortive

source. CRRI, 1990.

V20 A (F1)

Genotype Parentage Pollen Spikelet M/Ra

fertility fertility

(%) (%)

IET10158 Swarnadhan/NLR9674 0 0 M

IET10428 IR4219-35-3/IR4.570 0 0 M

IET11350 Bas370/CRR88-1-7-1-3 10.0 9.6 WM

IET10849 CR157-392/OR 67-21 0 0 M

IET11062b B29826/SR62-31-4 54.6 49.9 PRIM

IET12020 Sona/Basmati 370 9.1 7.0 WM

IET10851 Samridhi/IR36 0 0 M

IET11721 0 0 M

IET11811 IR36/TR17 0 0 M

IET11668 Co. 37/6551 0.6 0 M

IET10881c Ryllored/Palman 64.8 61.5 PRIM

IET10983d WGL23022/Surekha 73.8 71.7 PRIM

IET10503 Sona/IR28 0 0 M

IET10451 T90/IR8//RPW 6-13/// 8.2 6.0 WM

IET9994 Sona/ARC14529 15.0 13.1 WM

IET10763 IR36/IET7916 24.8 21.1 WM

IET9831 Prasanna/IR50 23.0 15.3 WM

IET9292 CO13/IR26 16.0 12.6 WM

IET11004 ES280/1-2/Ptb 33 49.7 29.6 PRIET11785 69.1 61.8 PR

IET10516 Phalguna/TKM6 45.3 40.8 PR

IET9824 Rasi/Dular 70.1 63.8 PR

IET11001 IR36///Suphala/PR3880// 32.9 28.6 PR

IET10508 IR50/IET7918 50.0 44.7 PR

IET9288 Jaya/Ptb 33 60.6 44.5 PR

IET9961 IR8 mutant 70.0 63.9 PR

IET9586 IET4141/CR98-7216 58.6 29.9 PR

IET10830 CR157-392/OR57-21 94.7 80.0 R

IET98 I9 Ratna/Zagar 96.8 91.5 R

IET10458 IET2886/Annapuma 92.1 81.0 R

IET9979 Phalguna/IR50 87.3 84.5 R

IET9798 Pusa 186-10-45/Pusa 2-21 84.9 83.2 R

IET11057 Rasi/IET7332 86.4 81.5 R

IET10462 Nam Sagui 19/IR4215// 91.6 89.5 R

IET 10463 92.1 91.1 R

IET10435 Sel. from IRTP 12140 89.7 87.4 R

IET11722 IET7615/RP79-5 94.1 83.5 R

Siam 29/Mahsuri

CR222/Parijat

IR9219-209-3-2

aM = maintainer, R = restorer, P = partial, W = weak. bIETI1062: 40% of F1 plants completely sterile.cIET10881: 66.7% of F1plants

highly sterile (96.8-99.1% pollen sterility). dIET109X3: 20% of F1 plants completely sterile.

IET11062, IET10881, and IET10983 heterozygous fertility restoration genes;

were both effective maintainers and they interacted differently with CMS line

partial restorers for V20 A. This indicates V20 A.

that these three varieties might have

The growth duration of hybrid combina-tions used in commercial rice production

in China (Shanyou 63, Weiyou 64) is

mainly determined by restorer lines. To

shorten the growth duration of hybrid

rices for a cropping system of rice -

wheat - rice or rice - rape - rice and to

extend hybrid combinations derived from

long-duration restorer lines to short-

duration rice regions and to mountainous,high altitude regions, we developed a

CMS line with incomplete dominance of

short duration.

In 1985, we crossed Zhenshan 97 B

with a shorter duration plant selected

from the F2 ofO. longistaminata / Liuzhou

wild rice (O. sativa L. f.spontanea).

Zhenshan 97 A was backcrossed with



11/26

that short-duration line for eight genera- Days to heading of CMS lines, restorer lines, and F 1s, and growth duration and grain yield of F1s.a

tions. A new CMS line was named Grain yieldZaoxian A in 1989. Days to heading Growth

Zaoxian A is still classified as a WAHybrid combination duration t/ha Percentage compared to

type. It is semidwarf (68 cm tall), averages value Check Check Check

104 spikelets/panicle, with a 1,000-grain

weight of 26.0 g. It also has long (1.62 m),Zaoxian A/R2

Zaoxian A/R1 78 111 94.5 90 127 9.6 112 121 11378 113 95.5 92 128 9.4 110 119 111

well-exserted (73.5%) stigma, and its Zaoxian A/R3 78 115 96.5 92 128 9.2 108 116 108outcrossing rate is high (55.3%). Zhen Shan 97 A/R1 (check 1) 75 111 93.0 112 148 8.6 100

three long-duration restorer lines, and

P1 P2 Mid-parent F1 (d)

1 2 3

In 1990, we crossed Zaoxian A with V20 A/R5 (check 3)Zhen Shan 97 A/R4 (check 2) 75 88 81.5 92 130 8.0 10075 87 81.0 90 127 8.5 100

tested yield capacity in a field experiment check 3 are the national checks of China and check 2 is the provincial check of Sichuan Province in the regional test of hybrid rice.aR1 = Minghui 63, R2 = 086, R3 = Mingdian 501, R4 = Zhalyeqing 8, R5 = Ce 64. P1 = CMS line, P2 = restorer line. Check I and

in Chengdu. Plots (2.5 m2) were laid out

in a randomized complete block design

with three replications.

The period to heading of F1s related to

Zaoxian A was about 20 d shorter than

those of the restorer lines and shorter than

the mid-parent values (see table). The

period to heading of F1s related to other

CMS lines was about 10 d longer than the

mid-parent values and longer than those of

the restorer lines.

This indicates that days to heading of

restorer lines is dominant over that of

CMS lines Zhenshan 97 A and V20 A.

Days to heading of Zaoxian A was

incompletely dominant over that of the

restorer lines.

Grain yields of hybrid combinations

derived from Zaoxian A were higher than

yields of national check Shanyou 63,

although hybrid growth durations were

about 20 d shorter than that of Shanyou 63.

Yields were significantly higher than those

of Shanzhai 8 and Weiyou 64, which had

almost the same growth durations as the

hybrids.

appears to be incompletely dominant over

the long duration of restorer lines, making

Zaoxian A valuable for rice production and

for hybrid rice breeding.

The short duration of Zaoxian A

Natural outcrossing on two Seed set on 2 cytosterile lines at RARS, R.S. Pura, India, 1989 wet season.cytoplasmic male sterilelines in northern India

Grains/panicle (no.) Total MeanA line B line Planting grains seed set

ratio Filled Unfilled (no.) (%)

J. S. Bijral, T. R. Sharma. B. B. Gupta, RR988 A CH988 1:1 68 850 918 7.4

K. Singh, and C. L. Raina, SKUAST,RR39 A K39 1:1 142 1101 1243 11.0

Regional Agricultural Research Station

(RARS), R.S. Pura 181102, India

We studied the extent of outcrossing incytoplasmic male sterile (A) lines

RR988 A and RR39 A (CMS-WA

cytoplasm developed at Pura, Jammu,

and Kashmir). The cytosterile lines were

surrounded by a single row of their

respective maintainer (B) lines (CH988

and K39). Plant spacing was 20 30 cm.

To synchronize flowering and prolongthe pollen supply, maintainer lines were

seeded 3 d earlier and 4 d later than the

cytosterile (A) lines. All lines were

transplanted at the same time, at 2

seedlings/hill. The flag leaves of the

cytosterile lines were not clipped.

The main panicles of 10 randomly

selected plants of each cytosterile linewere harvested individually and filled

and unfilled grains/panicle counted.

Outcrossing rate was low, probably

because of poor panicle exsertion of

cytosterile lines (see table).

Yield potentialWe evaluated 155 varieties and experi- Seventy-four entries failed to produce

Screening rice varieties and mental lines for internode elongation grain. Among surviving entries, 17

breeding lines for internode ability under field conditions. Entries produced 9-12 internodes, with total

elongation ability under field were seeded 13 Apr 1989 in two 5-m internode lengths of 126-215 cm (see

conditionsrows, 25 cm apart. table). These lines also had much better

Water depth reached 190 cm the first kneeing ability.

R. V. Singh, Crop Research Station week of Oct. Plant height, number and Maturity ranged from the last week of

(CRS), Ghagharaghat, Bahraich 271901, length of internodes, kneeing ability, Nov to the first week of Dec. Locally

Uttar Pradesh (UP); J. L. Dwivedi maturity, and phenotypic acceptability popular variety Jalmagna matured the

(present address: Plant Breeding, were observed. Maximum length of three first week of Dec, 233 d after seeding.

Genetics, and Biochemistry Division, consecutive elongated internodes was While Jalmagna was highest in total

IRRI); and O. P. Verma, CRS, Ghaghar- derived from the sums of three adjacent internode elongation, four other entries

aghat, Bahraich 271901, UP, India internodes. exceeded its maximum three consecutive

10 IRRN 16:4 (August 1991)


12/26

internode elongation (see figure). Length

of maximum elongating three adjacent

internodes ranged from 54 to 93 cm. It

took an average of 13.6 d for one

internode to form (computed as number

of days between start of flooding and

flowering, divided by total number of

elongated internodes). An estimate of

number of days required for maximum

elongation of three adjacent internodes is

41 d. These internodes were probably

formed during the highest water stagna-

tion period starting the first week of Oct.

The maximum elongation of three

adjacent internodes gives an indication of

capacity for elongation in a prolonged

Performance of promising lines under natural field conditions in Uttar Pradesh, India.

Promising lines Plant Internodes

height Days to Date of

Designation Parentage (cm) no. Length maturity maturity

(cm)

IR45478-B-3 Baisbish/IR 19245-76-2- 1-3-3 167 12 126 239 8 Dec

NDGR87-2 Jalmagna/Sona 217 9 126 237 6 Dec

NDGR87-2-1-3 Jalmagna/Sona 220 9 127 245 14 Dec




IR45478-B-4 Baisbish/IR19245-76-2-1-3-3 223 10 146 239 8 Dec

IR45468-15-GR-5 Baisbish/IR56 232 10 149 238 7 Dec

NDGR1045-125-103 RP/LMN111 238 10 160 236 5 Dec


IR45468-B-10 Baisbish/IR56 237 10 168 240 9 Dec



RP2078-58-74-1 Mansarovar/CO 14 268 10 186 231 6 Dec

RF'2078-63-81-1 Mansarovar/CO 14 250 10 191 236 5 Dec

RP2078-56-71-39 Mansarovar/CO 14 269 10 195 237 6 Dec

Jalmagna Pureline selection 290 13 196 233 2 Dec

NDGR1045-38-127- RP/LMN111 255 11 215 228 21 Nov

113

period of rapidly rising water, in this case

190-200 d from seeding. Elongation of

the central internode of the longest three

internodes (position 3-5 counting from

the top of the figure) may correspond to

the onset of water 40 d before flowering

and/or to the extra stimulus to internode

growth at panicle initiation, which was

also 30-40 d before flowering. Further

experiments using a group of varietieswith a wider spread of flowering dates

may help distinguish between these two

causes.

Number of elongated internodes and

maximum elongating three adjacent

internodes may be used to assess promis-

ing lines for elongation ability. Further

study is needed to determine the relation-

ship between elongation ability and yield

potential.

Surveys of disease or insect incidence/severityin one environment are useful only if the

information is related to other variables (e,g.,

climatic factors, crop intensification, cultivars,

management practices, etc.). By itself,

information on incidence in one environment

does not increase scientific knowledge.

Internode length and three maximum elongating internodes.

IRRN 16:4 (August 1991) 11


13/26

Elongation ability indeepwater rices

O. P. Verma, Crop Research Station

(CRS), Ghagharaghat, Bahraich 271901,

Uttar Pradesh (UP); J. L. Dwivedi

(present address: Plant Breeding, Genet-

ics, and Biochemistry Division, IRRI);

and R. V. Singh, CRS, Ghagharaghat,

Bahraich 271901, UP, India

We studied the elongation ability of 12

deepwater rice varieties and 24 advanced

breeding lines during 1989 wet season.

Entries seeded in pots were submerged in

120-cm-deep water 42-49 d after seeding.

Internode, leaf sheath, and leaf blade

lengths were measured on 10 plants

before and after flooding. Recovery or

submergence tolerance was scored 10 d

after water was drained.

By and large, the traditional floating

rices had higher total elongation than did

the breeding lines (see table). Total plant

elongation after 7 d water treatment

ranged from 8.5 cm (entry ACC33745

was rejected and is not in the table) to

66.5 cm (TCA4).

TCA4 had the highest internode

Plant elongation and regeneration ability of rices with different deepwater survival strategies. a

Elongation (cm)Variety

Internode Leaf LeafSubmergence

tolerance scoresheath blade

TCA4 51.5 7.6 7.4 7

NDGR401

NDGR40649.0 2.7 3.7

42.75

NDGR4045.0 5

42.3 3.7 16.4 5

ACC38876 34.3 9.4 7.3 5Jalmagna 31.3 5.0 6.0 9

NDGR402 28.4920356

6.3 18.6 322.0 4.7 20.3 3

IR11141-6-1-4 16.9 8.4 18.7 5

Nam Sagui 19 13.1 9.6 2.7 3

IR39657-4-502-1-3-2 12.0 4.7 12.0 5

TCA7819 11.0 20.3 10.0 5

ACC189734.0 15.7 4.0 5

2.0FR 13A

16.0 5.0 3

0.4 20.6 4.0 3

aUnderlining indicates relatively high reliance of the plant on the corresponding survival strategy.

8.0

IR39657-B-B-1

elongation, followed by NDGR404 and sudden submergence.

NDGR406. Higher elongation values indicate

Leaf sheath and leaf blade elongation as relatively high reliance on the corre-

high as 15.7-20.6 cm were recorded in sponding survival strategy. Some

920356, ACC18973, TCA7819, varieties rely on internode elongation,

NDGR402, IR39657-B-B-1, and FR13A. leaf (sheath, blade) elongation, and/or

Since leaf elongation ability is limited, submergence tolerance. Breeding

these entries might be suitable for areas strategies could incorporate some or all

that have sudden floods of limited depth. of these survival characters, depending

scores 1-3 will be helpful in areas prone to

Varieties with submergence tolerance on the target area.

~.

Pest resistancediseasesDisease incidence was scored 21 d after

Utilization of sources of

resistance to bacterial blight(BE) in China

Shen Ying, Zhu Peiliang, and Yuan

Xiaoping, China National Rice Research

Institute (CNRRI) Hangzhou 310006; He

Hui and Zhu Jinwen, Plant Protection

Department, Zhejiang Agricultural

University, Zhejiang 310029, China

We screened 99 rice cultivars and lines

against BB caused by Xanthomonas

oryzaepv. oryzae (Xoo) at CNRRI

Experiment Station during Apr-Oct 1990.

Thirty-day-old seedlings were

transplanted in two rows of 14 hills each

at 20- 20-cm spacing, with two replica-

tions. One row each of local susceptible

check Jin-Gang 30 and resistant check

IR26 were transplanted between each

entry and around the experimental field.

The plot was fertilized with 75-37.5-

25 kg NPK/ha.Seven pathogenic groups of Xoo with

varying virulence, based on their reaction

on five Chinese differentials, were pro-

vided by Yin Shangzhi, Jiangsu Academy

of Agricultural Sciences (Table 1).

Test plants were clip-inoculated with a

concentration of 3 108 CFU/ml from

maximum tillering to initial booting stage.

inoculation.

Eight varieties showed resistance to

the pathogenic groups (Table 2). Theyhave good agronomic traits and high

yield potential, and have been used as

resistance sources for breeding.

the BB pathogenic groups and the rice

varietal types appropriate for different

rice cropping regions, Xa-3 resistance

sources are best in japonica rice cropping

Given the geographical distribution of

Table 1. Pathogenic groups of Xoo in China.

Reactiona on indicated differential varieties

Pathogenic Representative

group isolate Jin-Gang 30 Tetep Nan

-Jing 15 Java 14 IR26

I JS97-2 S R R R R

II KS-1-21 S S R R R

III JS158-2 S S S R R

IV Zhegiang 173 S S S S R

V 1358 S S R R S

VI OS-198 S R S R R

VII JS49-6 S R S S R

aR = resistant, S = susceptible.

12 IRRN 16:4 (August 1991)


14/26

Table 2. Resistance of rice cultivars (lines) to 7 pathogenic groups of BB in China 21 d after inoculation. inoculation.

Reactiona to pathogenic groupOne accession of O. officinalis

Variety (line) Origin Use (105365) showed high antibiosis to GLHI II III IV V VI VII and resistance to both RTBV and RTSV

Milyang 23 1 5 3 5 3 5 5 Korea Hybridization

DV85 5 7 3 3 1 5 3 Bangladesh Hybridization O. nivara (102175, 105333), two ofO.

infection (see table). Two accessions of

IR54 3 3 3 3 5 3 3 IRRI Hybridization

IRBB 7 3 1 1 1 3 1 1 IRRI Resistance source

C702015Resistance source

1 3 3 3 3 3 5 Taiwan (China) Resistance source

C722355 1 3 3 5 5 3 3 Taiwan (China) Resistance sourceSuwon 339 1333351 Korea Resistance source

BR568-15-4-2-2-3 3 3 3 1 3 3 3 Bangladesh

aBy the Standard evaluation system for rice scale 0-9.

regions of the northern part beyond the Yangtze River. Xa-4, xa-5, and Xa-7

Yangtze River. Xa-3, Xa-4, xa-5, Xa-6, or resistance sources are needed in indica

Xa-7resistance sources are best in indica- rice cropping regions in the south China

japonica rice cropping regions along the coastal area.

Resistance to tungro in somewild relatives of rice

N. Kobayashi, R. Ikeda, and D. A.

Vaughan, IRRI; and S. Shigenaga, Kyoto

University, Japan

We tested 16 accessions of wild rice

Oryza spp. for antibiosis to green

leafhopper (GLH) Nephotettix virescens

Distant, resistance to rice tungro bacilli-

form virus (RTBV) and rice tungro

spherical virus (RTSV) infection, and

tolerance for tungro.

To test for antibiosis, a 10-d-old

seedling of each accession was placed in

a test tube with five GLH nymphs (2d

instar), with 10 replications. Antibiosis of

each accession was rated on a 1-5 scale

by counting surviving GLH nymphs

every day for 3 d. Those same seedlings

(15-d-old) were inoculated with 10

viruliferous GLH adults/seedling for 4 h.

Leaves were individually sampled 3 wk

after inoculation, and tested for RTBV

and RTSV by enzyme-linked immuno-

sorbent assay. Disease severity of each

accession was scored at 4 wk after

Reactions of wild species of rice to GLH and tungro disease.

IRGC

no. to GLHa (no.) B+S B S

Anti- Plants Infected plantsb (%) Average

Genome Species acc. Origin biosis tested severityc

AA O. nivara 102463 Bangladesh 5 38 74 26 0 3

102175 India 1 18 0 78 0 5105333 India 1 49 2 59 0 2105409 Sri Lanka 5 39 69 18 3 2

105417 Sri Lanka 4 18 50 11 6 2105456 Sri Lanka 4 3 67 33 0 5

BB O. punctuta 103896 Tanzania 1 17 0 53 0 2

BBCC O. minuta

CC O. eichingeri

CC O. officinalis

CC O. rhizomatis

CCDD O. latifolia

AA O. sativa

ARC11554

Utri Merah

TN1

IR22

105158

101126

101141

105414

105365

105394105660

105448100914

21473

(check

16680

Kenya

Philippines

Philippines

Sri Lanka

Thailand

ChinaSri Lanka

Sri Lanka

Mexico

varieties)India

Indonesia

Taiwan

Philippines

2

1

1

2

1

31

1

1

5

5

5

49

20

36

47

27

3213

4

23

54

54

53

57

0

5

0

47

0

915

5057

2

2

96

90

37 0 3

50 0 3

56 0 5

43 0 5

0 0 2

81 0 3/7

d

31 8 5

25 0 3

0 13 3

39 0 3

52 0 3

4 0 9

10 0 9

punctata (103896, 105158), and two of

O. minuta (101126, 101141) showed high

antibiosis to GLH and resistance to

RTSV infection. Even with low antibiosisto GLH and severe infection with RTBV

and RTSV, three accessions of O. nivara

(102463, 105409, 105417) showed low

scores for symptom severity, indicating

tolerance for tungro.

These results suggest that a number of

new sources of resistance to both RTBV

and RTSV may be found among the wild

rices.

Distribution of rice varietiesresistant to bacterial blight(BB) in Yunnan, China

Chen Yong and Xinhua Liao, Yunnan

Academy of Agricultural Sciences,

Kunming 650205; Yuefeng Xie and

Duanpin Zhang, Huazhong Agricultural

University, Wuchang, China

We screened 4,091 Yunnan rice varieties

for resistance to BB caused by

Xanthomonas oryzae strain Jiangling

691: 6% were resistant, 84% weresusceptible, and 10% were moderately

resistant. The frequency of resistance

differed within rice classifications

(Table 1).

glutinous rices.

among japonica-irrigated-glutinous,

japonica-irrigated-nonglutinous, and

japonica-upland-glutinous rices. Mean

Table 1. Distribution of BB-resistant rices inYunnan, China.

Resistance was more frequent among

Table 2 shows more resistant varieties

Varieties Resistant varietie

(no.) no. %

Classification tested

Indica 2186 83 3.8

Japonica 1905 159 8.4Irrigated 3233 202 6.2

Upland 858 40 4.7aScale of 1 (resistant) to 5 (susceptible).

bInfected with both RTBV and RTSV (B+S), with RTSV (S), or with RTBV (B).

cScale Nonglutinous 3183 159 5.0

1 (no symptoms) to 9 (more than 50% plant height reduction and yellow to orange leaf discoloration), using Nasanuddin et al scale. Glutinous 908 83dSegregating.

9.

IRRN 16:4 (August 1991) 13


15/26

resistance scales of these types are signifi-

cantly lower than that of other types. In

terms of average resistance, Yunnan rices

could be classified into three significantly

different resistance groups.

Presence of rice tungrobacilliform virus (RTBV) in

xylem cells of tungro-infected rice

F. C. Sta. Cruz and H. Koganezawa,

Plant Pathology Division, IRRI

Earlier studies have shown that RTBV

and rice tungro spherical virus (RTSV)

are restricted to the phloem tissues of

infected plants, and it has been suggested

that only phloem feeding by green

leafhopper (GLH) causes tungro infec-

tion. On GLH-resistant cultivars, how-

ever, it has been observed that GLH feedsmainly from the xylem and transmits

primarily RTBV. We examined the

location of RTBV in host cells in relation

to tungro transmission.

Rice seedlings (1 5 d old) of tungro-

susceptible cultivar TN1 and GLH-

resistant cultivar ASD8 were inoculated

with rice tungro viruses (RTVs) using

adult GLHs. The leaf blades of infected

plants were collected 30 d after inocula-

tion for electron microscope study.

RTBV particles were found in xylem

parenchyma cells as well as in phloem

Table 2. Distribution of resistant varieties in 8 classes and the significance level test of mean resistance

scales.

Total Resistant varieties

(no.) resistanceClassificationMean

no. % scale

Indica-irrigated-nonglutinousIndica-irrigated-glutinousIndica-upland-nonglutinousIndica-upland-glutinous

Japonica-irrigated-nonglutinous

Japonica-irrigated

-glutinous

Japonica-upland-nonglutinousJaponica-upland-glutinous

Total

1832303

3120

679

419641166

4091

aMeans followed by the same letter are not significantly different.

651701

70

502415

242

3.555.610

5.0010.31

11.933.749.045.92

8.02 b7.76 b8.35 a7.80 b7.38 c

7.26 c7.96 b7.39 c

cells of tungro-infected TN1 and ASD8 These results suggest that GLH can

(see figure). RTSV was observed only in transmit RTBV directly to xylem cells,

phloem cells and around the boundary where the virus multiplies and causes

between xylem and phloem tissues. In infection. They also support the observa-

initial observations, RTBV in xylem cells tion that GLH feeds mainly from the

were found in the third and fourth leaf xylem of GLH-resistant cultivars and

position of infected plants. transmits predominantly RTBV.

RTBV in xylem parenchyma cells of rice cultivars TN1 (a) and ASDS (b). R = ribosomes.

Integrated germplasm improvementupland

Four upland rice varieties Table 1. Mean performance of 4 newly released varieties in Sierra Leone.released in Sierra Leone

Height Duration Panicles Mean grainVariety Original name (cm) (d) (no./m2) yield (t/ha

A. H. Hilton-Lahai, S. S. Monde, and

M. S. Mansaray, Rice Research Station, ROK17 LAC23 119 138 186 3.1

Rokupr, Sierra Leone ROK18 IDSA-6 96 117 174 2.9ROK19 FARROX 299 116 115 172 2.8

The uplands account for about 70% of the ROK16rice area in Sierra Leone. In 1988, four

ROK20 IRAT161 103 118 178 3.0

NGOVIE (local) 128 132 183 2.6

new varieties (ROK17, ROK18, ROK19,

ROK20), all foreign introductions, were In varietal trials conducted for two ROK17 is a local japonica selection

released for upland planting (Table 1). seasons in farmers fields in three from Liberia. It is a medium-duration

These varieties surpassed check variety villages in the North-Western Region, the cultivar, with bold grains much like

ROK16 in overall performance and new varieties consistently outyielded ROK16. It is, however, more resistant to

farmer acceptability in field tests over local check ROK16. Table 2 shows grain diseases and lodging than ROK16 and is

four seasons. yields and some properties of the soils. suited to the high rainfall areas of East

14 IRRN 16:4 (August 1991)


16/26

Table 2. Yield of 4 new upland rice varieties in farmers fields in Kambia District, Sierra Leone.

1986-87Variety

1987-88

Kamaranka Funkia Petifu Mean Gberika Rochain Rochint Mean

ROK 17 2.2 1.9 2.1 2.1 2.9 2.4 2.4 2.5

ROK18 2 .0 2.8 2.3 2.4 2.8 2.8 2.3 2.4

ROK19 2.8 2.3 2.0 2.2 2.4 2.0 2.3 2.2

ROK20 2.4 2.1 2.3 2.3 2.7 2.2

ROK16 (check) 1.8

2.4 2.3

1.6 1.8 1.7 1.5 1.3 1.7 1.5

CV (%) 12.2 14.6 18.2 15 19.7 22.9

LSD (0.05)

14.4 19

8.2 8.2 8.2 8.2 8.2 8.1 8.2 8.2

Soil Sandy Loam Gravelly Clay Sandy Loam

pH (water)

loam

5 0 4.9 5.1 5.5 4.8

CEC (meq/100g) 11.4

5.0

10.2 13.2 15.1 9.9

Organic C (%)

11.1

1.2 0.9 1.4 2.1 0.8 1.8

Total rainfall (mm) 2,156 2,256

clay loam loam loam

and South Sierra Leone. ROK17 is

preferred by North Sierra Leone farmers

because it is awnless, which makes

threshing with the feet less painful. It

also has better cooking and eating

qualities.

ROK18, ROK19, and ROK20 are

short-duration varieties superior to

ROK16 in plant type, disease resistance,

and phenotypic acceptability. They arerecommended for the low rainfall areas

of the north. Grain size ranges from

slender to medium bold, as preferred by

northern farmers.

Integrated germplasm improvementirrigated~

ASD18, a blast (BI)-resistant Table 1. Reaction of ASDl8 to major diseases in Tamil Nadu, India.rice variety for Tamil Nadu

Reactiona

M. Rangaswamy, K. Mohanasundaram,

P. Shanmugasundaram, K. Ganesan, T.

Sundaram, M. Subrammian, D. Alice,

and M. Velusamy, Rice Research Station

(RRS), Ambasamudram, Tamil Nadu

627401, India

Bl-resistant, short-duration, medium-

slender rice culture AS34011, selected

from the cross ADT31/IR50, was

released as ASD18 by the Tamil Nadu

G.D. Naidu Agricultural University in

Jan 1991. It is recommended as analternative to IR50 and TKM9 for

summer (Mar-Jun), first season (Jun-

Sep), and second season (Nov-Feb)

planting.

ASD18 is 90 cm tall with 105-110 d

growth duration. Mean grain yield was

7.3 t/ha over 6 yr at RRS, 5.7 t/ha in

multilocation trials over 2 yr at seven

research stations throughout Tamil

Nadu, and 5.9 t/ha under Adaptive

Research Trials (ART) in 52 farmers

fields. Total dry mass was 18.2 t/ha (8.5

t grain and 9.7 t straw) at Amba-samudram; potential grain yield was

10.1 t/ha under ART.

It is resistant to Bl and moderately

resistant to sheath rot and tungro (Table

1). It is resistant to brown planthopper

and stem borer and moderately resistant

to gall midge and leaffolder (Table 2).

Variety Blast Sheath rot Sheath

ASD-N blight

RTV

ADT-A DBE-A ASD-N ASD-A ADT-A CBE-A

ASDl8 1 3 3

IR50 3

7 4 5

TKM9 3

9 5 3

7 7 7 9 8 9

aBy the Standard evaluation system for rice (SES) scale. N = natural condition, A = artificial condition, ADT = Aduthurai, ASD

= Ambasamudram, CBE = Coimbatore.

5

9 79

Table 2. Reaction of ASDl8 to major pests in Tamil Nadu, India.

Reactiona

Variety BPH SB GM LF

ADT-A ASD-A ASD-N MDU-A MDU-A CBE-N ASD-A

ASD18 3 5 3 0 5

IR50 9 5

TKM9 9 9

7 5

3 3 9 73 0 9 7

aBY SES. BPH = brown planthopper, SB = stem borer, GM = gall midge, LF = leaffolder. ADT = Aduthurai, ASD =

Ambasamudram. MDU = Madurai, CBE = Coimbatore. N = natural condition, A = artificial condition, (-) = not tested.

Integrated germplasm improvementrainfed lowland

Three new varieties of short- Short-duration rices (120 d orless) coverduration rice released inCambodia

almost 25% of Cambodias rice area. In

the dry season, they are grown in about

10% of the area, either irrigated or with

R. C. Chaudhary and H. J. Nesbitt, IRRI- receding water. In the wet season, they

Cambodia; G. S. Khush, IRRI, Philip- are grown in about 15% of the area as a

pines; and Men Sarom, Agronomy rainfed lowland crop.

Department, Phnom Penh, Cambodia A number of traditional early varieties

IRRN 16:4 (August 1991) 15


17/26

Table 1. Some Chemical Characteristics of acid

sulfate soils at Unit Tatas Substation, Central

Kalimantan, Indonesia.

DepthCharacteristic

0-15 cm >15 cm

pH H2OOrganic C (%)

Total N (%)

P Bray (ppm)K (meq/100 g)

Ca (meq/100 g)

Mg (meq/100g)

Na (meq/100 g)CEC (meq/100 g)

A1 (meq/100 g)

H (meq/100 g)

Texture (%)

- Clay

- Silt

- Sand

4.0

2.8

0.4

1.7

0.2

0.41.2

0.2

22.0

14.0

1.0

37

62

1

4.0

1.7

0.2

1.3

0.1

0.30.9

0.3

37.0

16.0

0.8

45

54

1

was 90-60-50 kg NPK/ha. All the P and

K, and half the N were applied basally at

transplanting; the remaining N was

applied 30 d after transplanting. Pest

infestation was measured at peak

incidence.

BW267-3 had the highest grain yield,

followed by CR61-7039-236, IR6023-10

1-1, and IR19661-13-3-2 (Table 2).

BW267-3 and IR6023

-10

-1-1 are

intermediate tall, IR19661-13-3-2, and

CR261-7039-236 are semidwarf. These

four short-duration lines have the highest

number of panicles/m2 and can be

developed for the tidal swamps. Grain of

IR19661-13-3-2, IR6023-10-1-1, and

BW267-3 are long, slender; those of

Performance of short-duration rice varieties in tidalswamps of Indonesia

H. Rosmini, Banjarbaru Research

Institute for Food Crops, P.O. Box 31,

Banjarbaru, South Kalimantan, Indone-

sia

We screened 23 promising lines to

identify short-duration rice varieties that

yielded well in sulfate acid soils at Unit

Tatas substation, Central Kalimantan,

1987-88 (Table 1). Seedlings (21 d old)

were transplanted at 25- x 25-cm spacing

in 7.5-m2plots in a randomized block

design with four replications. Fertilizer

adapted varieties, IRRI-Cambodia

Project trials were conducted in 13

provinces over four seasons 1989-90.

Of 20 entries tested in 1989 and 10 in

1990, IR66, IR72, and IR13429-150-3-

2-1-2 (named Kru) were best (Table 1).

They yielded 4 t/ha across 13 locationsduring dry season 1990, against 3.2 t/ha

of the highest yielding check. (IR36 and

IR64 were the check varieties.) In 38trials over four seasons and 2 yr, IR66,

IR72, and Kru yielded 4.2, 4.1, and 4.4

t/ha, respectively, compared to 3.7 t/ha

from the check. Other agronomic

characters are given in Table 2.

These three varieties were tested infarmers fields in 13 provinces, with a

traditional early variety added as local

check. At some of 75 locations, IR66,

IR72, and Kru yielded more than 6 t/ha

(average 2.5-2.8 t/ha). A few hundred

tons of seed were multiplied by the

farmers themselves during 1990.

are planted; varieties such as IR36, IR42, varieties introduced via Vietnam (such as

IR50, and IR66, and some IR-based NN3) are also popular. To identify more

Table 1. Yield of 3 new varieties during 1989 and 1990 wet seasons in Cambodia.

Field a (t/ha)

LocationIR66 IR72 Kru Check

1989 1990 1989 1990 1989 1990 1989 1990

Tonle Bati 5.1 ab - 5.2 ab - 5.7 a - 4.8 bc

Por Lors 3.6 a - 2.6 b - 2.9 ab - 2.9 ab

Ballang 4.8 3.8 ab 4.9 3.6 ac 5.2 2.5 be 4.1

Day Eth 2.7 be 5.1 bc 2.9 bd 4.7 bc 3.9 a 5.8 a 3.1 ab 4.8 c

Prey Kabas 3.6 3.6 1.8 3.2 2.9 3.2 1.8 2.9

4.0 a

Kbal Po 3.2 a 3.0 ab - 3.2 ab - 2.8 b

Chhbar Mom 5.4 ab 3.3 5.4 ac 3.2 5.3 ac 3.7 4.6 ae 2.5

Kompong Siem 2.5 bc - 2.6 bc - 3.0 a - 2.7 b

Prey Khmer 5.4 ae 5.1 ab 5.0 be 4.9 ab 6.6 a 5.4 a 5.9 ac 4.9 ab

Toul Bakha 4.0 ab 3.5 a 4.2 a 3.3 a 4.1 ab 3.1 ab 3.2 bd 2.8 ac

Kirivong 4.2 b - 3.6 bc - 4.0 bc - 4.2 b

Chumcar Daung 5.7 ad 5.2 ab 6.6 ab 5.4 ab 6.5 ab 5.2 a 5.7 ad 4.8 b

Kap Srau 4.7 ab - 4.6 ad - 4.0 cd - 4.8 a

Prey Phdau

Ta Saang

5.9 ab 4.5 ab 5.1 a 3.9 c 4.8 ac 5.1 a 4.1 be 4.6 ab

2.1 ad 2.5 ab 2.7 ad 2.0 bd 2.3 be 2.7 a 2.7 ad 2.4 ac

Bek Chan 5.9 5.6 a 5.9 5.0 ac 6.8 5.2 ah 6.6 3.9 d

Tuk Will 2.3 2.0 ab 2.0 1.8 cd 2.3 2.1 a 1.7 1.6 d

Slakou 2.0 ad - 1.7 d - 2.2 ab - 1.9 bd

Toul Lapao 1.5 1.3 1.3 1.3

Toul Chrem Chrom-

1.9 ac-

2.7 ab-

1.5 bc-

2.1 acaAny two means having a common letter at a location in a year are not significantly different by DMRT.

Table 2. Grain yield and ancillary characters of 3 early varieties in dry season (13 locations) and wet season (20 locations) trials in Cambodia, 1990.

Duration (d) Plant height (cm) Panicle length (cm) Grains/panicle Panicles/m2 Yield (t/ha) PAcpa

Variety

Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet

IR66 1061.3 1100.8 752.5 85.81.5 21.30.10 22.80.4 898.4 1016.0 32915.0 28615.7 4.0 3.9 3.20.6 2.070.42

IR72 1151.2 1140.8 722.5 81.81.9 21.90.46 21.70.4 859.5 864.1 30618.6 29215.8 4.0 3.6 2.00.8 2.210.40

KRU 1121.0 1130.8 752.6 83.01.9 22.90.46 21.40.3 8811.0 905.34 37323.0 31717.5 4.1 3.9 2.70.7 2.140.34

Check I111.2 1111.0 773.0 87.82.0 21.70.51 22.40.5 7514.0 803.8 30819.6 29115.5 3.2 3.6 4.00.5 2.860.43

aPAcp = phenotypic acceptability.

Integrated germplasm improvementtidal wetland

16 IRRN 16:4 (August 1991)

-- - -

--

-

-

-

-

-

-


18/26

Table 2. Yield of 23 promising rice cultures at Unit

Tatas Substation, Central Kalimantan, Indonesia,

1988.

Plant Days Panicles Grain

Culture ht to /m2 yielda

(cm) maturity (t/ha)

IR19661-13-3-2 104.7 130 214 5.1 b

BW267-3 118.2 120 232 6.7 a

IR6023-10-1-1 118.8 125 216 6.3a

CR261-7039-236 96.7 125 239 6.4 a

ROHYBl5-WAr

-125.8 145 201 2.9e

3-3

BWl00 119.3 140 155 2.8 e

BR51-120-2 115.1 140 200 2.7 efg

CR1009 104.2 150 190 2.7 efg

IR9217-58-2-2 98.4 135 228 3.6 d

IR9217-6-2-2-2-3 108.5 135 205 3.6 d

Pankaj 106.9 145 196 4.4 c

IR13146-45-2 108.0 135 212 3.8 d

IR8192-31-2-1-2 101.1 140 147 2.4 fg

IR21586-R-31-1 110.4 145 198 2.4 fg

ITA230 102.7 140 217 4.4 c

IR14753-120-3 102.3 125 212 2.3 g

IR29723-88-2-3-3 100.4 140 179 2.3 g

IR33353-64

-1-2-1 100.8 125 255 2.2 gh

IR19657-87-3-3 104.7 135 190 2.1 gh

IR4422-480-2-3-3 101.1 135 166 1.8 h

IR31917-31-3-2 95.6 140 171 2.4 fg

IR52 95.2 115 247 1.3 i

IR21836-90-3 107.7 140 208 1.1 i

aValues followed by a common letter are not significantly

different at the 5% level by DMRT.

CR261-7039-236 are medium. Amylose

content is 26-28%.

These four lines are resistant to leaf

blast and stem borer.

Mean cumulative N loss by ammonia volatilization

source of N, and application method.

CROP AND RESOURCEMANAGEMENTFertilizer management

Influence of organic andinorganic amendments,modified urea, andapplication methods onammonia volatilization in soil or mixed in the soil surface (see tablesaturated calcareous soil for treatments).

Three-

kg air-

dried soil, equilibratedwith soil amendments (20 t/ha) for 4 wk

under saturated conditions, was placed in

5-liter wide-mouth glass bottles. N was

applied at 150 kg/ha on the surface of the

The bottles were connected with an air

M. Singh, Indian Institute of Soil Science, compressor to flush out evolved NH3

Z-6, Zone-I, Muharana Pratap Nagar, from the soil (4-5 liter/h). The NH3 was

Bhopal 462011; and T. A. Singh, G.B. trapped in 2% boric acid mixed with an

Punt University of Agriculture and indicator. Boric acid was titrated against

Technology, Pantnagar, Nainital 0.05 NH2SO4 at regular intervals for 30

263145, India d.

Ammonia volatilization from urea significantly reduced cumulative NH3

depends on such factors as rate of volatilization. The reduction in NH3 loss

hydrolysis of urea, concentration of appears to be due to a lowering of soil pH

NH+4-N in the soil, and pH. Coating urea on equilibration with soil amendments

with some material can reduce NH3 (see figure).

volatilization. The formation of stable ammonium

We measured NH3-N volatilization sulfate in soils amended with gypsum and

from urea, neem cake-blended urea pyrite may have contributed to reduction

(NCBU), and neem oil-coated urea of NH3 loss. Reduction of NH3 volatiliza-

(NOCU) from a saturated calcareous soil tion from soil amended with rice husks

(pH 8.25, 1.25% organic C, 23.7% and straw may be due to sorption of NH+4

CaCO3, and CEC 19 meq/100 g soil) by organic matter.

amended with gypsum, pyrite, rice straw, NH3 volatilization loss from soils

and rice husks. A forced draft chamber amended with NOCU was lower because

technique was used to trap ammonia. a thin layer of neem oil around the prilled

urea acted as a physical barrier, reducing

in saturated soil, as influenced by soil amendment, the rate of N release and thus the concen-

Application of soil amendments

Cumulative N loss (%)

Soil

amendment N source Application method

Urea NCBU NOCU Surface Surface

applied mixed

Gypsum 11 11 4 11 6

Pyrite 10 7 4 8 6

Rice straw 12 12 5 13 6

Rice husk 13 13 5 13 7

Control 32 34 10 32 18

LSD (0.05) Amendment x

Source of N

2

Application

method

3

. .Soil pH on equilibration with amendments undesaturated conditions.

IRRN 16:4 (August 1991) 17


19/26

tration of NH4+ in the soil. NH3 volatiliza- N was surface mixed rather than surface

tion from NCBU and with uncoated urea applied. This may be because more of the Fertilizerwas the same. surface area of soil organic matter and

source, NH3 volatilization was less when ions. inorganic sourcesmanagement

Irrespective of soil amendment and N clay was available for sorption of NH4+-N

Fertilizer managementorganic sources

Effect of gypsum-enrichedbiogas sludge and farmyardmanure (FYM) on rice yield

G. Kuppuswamy, AR. Lakshmanan, and

A. Jeyahal, DNES Research Project,

Agronomy Department, Annamalai

University, Annumalainagar 608002,

Tamil Nadu, India

We evaluated the effect of biogas sludge

and FYM on rice yields in two successive

field trials, Jul-Oct 1989 and Nov-Feb1990. Rice cultivars were IR20 and

ADT37.

Soil of the experimental field the first

season was clay loam with pH 7.4; EC

0.6 dS/m; 0.44% organic C; and available

N, P2O5, K2O were 225, 14, 312 kg/ha,

respectively. Soil of the experimental

field the second season was clay loam

with pH 7.2; EC 0.5 dS/m; 0.43% organic

C; and 238, 23, 314 kg available N, P2O5,

K2O/ha, respectively.

The biogas sludge contained 1.5% N,

0.82% P2O5, and 0.75% K2O. FYM

contained 0.85% N, 0.35% P2O5, 0.688

K2O, and 58% water in season 1, and

0.75% N, 0.61% P2O5, 0.63% K2O, and

57% water in season 2. In both seasons,

N, P2O5, and K2O at 100, 50, and 50 kg/

ha were applied as urea, single super-

phosphate, and muriate of potash. The

experiments were laid out in a random-

ized block design with three replications

(see table for treatments).

Growth and yield attributes and grain

and straw yields were favorably influ-

enced by biogas sludge and FYM bothseasons. Added gypsum acted as an

absorbent, reducing the moisture content

of biogas wet sludge and FYM by 30 and

10%, respectively.

enriched biogas sludge both seasons. The

next best was enriched FYM. Enrichment

of wet biogas sludge with gypsum

increased yields 0.95 and 0.71 t/ha in the

first and second seasons, respectively.

Enriched FYM increased yields 0.67 and

0.56 t/ha.

Grain yields were highest with

Effect of gypsum-enriched biogas sludge and farmyard manure on rice yield.

Effect of irrigation andnitrogen on transplantedsummer rice yield and wateruse efficiency

A. K. Choudhury, M. Saikia, and

K. Dutta, Agronomy Department, Assam

Agricultural University, Jorhat, Assam,

India

We studied the effect of three irrigation

schedules and four N levels on grain

yield and water use efficiency of trans-

planted summer rice (Apr-Jul) 1987-89.

The soil was acidic sandy loam (pH

5.4), low in total N (0.065%), medium inavailable P2O5 (18 kg/ha; Bray and Kurtz

No.1), and low in available K2O (86 kg/

ha; neutral ammonium acetate method).

The rice variety used was IR50. Phos-

phate and potash were applied at 20 kg

each/ha. Average rainfall during the 3 yr

was 688 mm.

The experiment was laid out in a

randomized block design with three

replications. Treatments are given in

Table 1.

Irrigation schedule had no effect on

grain yield. During the summer season,rainfall increased from the early vegeta-

Panicles/m2 Filled grains/panicle Grain yield (t/ha) Straw yield (t/ha)Treatment

Season Season Season Season Season Season Season Season1 2 1 2 1 2 1 2

Biogas wet sludge

(10t/ha)

Biogas dried sludge

(10 t/ha)

Biogas wet sludge( 10 t/ha) enriched

with 250 kg

gypsum/haFYM (10 t/ha)

FYM ( 10 t/ha)enriched with250 kg

gypsum/ha

Gypsum (250 kg/ha)

Control

LSD (0.05)

384

385

413

341

385

330

324

1

354 98

365 99

412 109

343 99

407 107

324 107

313 97

11 2

71 7.5 3.7 13.0 4.9

71 7.8 3.8 13.7 5.1

74 8.4 4.4 15.3 6.2

72 7.3 3.7 12.6 4.8

74 8.0 4.3 14.7 5.8

70 6.8 3.5 11.5 4.7

70 6.6 3.2 11.0 4.6

2 0.2 0.1 0.5 0.2

Table 1. Effect of irrigation schedule and N level on

grain yield of summer rice in Assam, India.

Grain yield (t/ha)

1987 1988 1989 Pooled

Treatmenta

Irrigation

Continuous sub-mergence

7 cm water1 DADPW

7 cm water3 DADPW

N level (kg/ha)0

4080

120

LSD (0.05)

LSD (0.05)

2.2 1.4 2.7 2.1

2.0 1.6 2.7 2.1

2.1 1.6 2.8 2.2

ns 0.05 ns ns

2.0 1.7 2.2 1.92.2 1.4 2.7 2.12.0 1.5 3.0 2.2

2.2 1.5 3.1 2.3ns ns 0.12 0.14

aDADPW = days after disappearance of ponded water.

18 IRRN 16:4 (August 1991)


20/26

tive stage to maturity. This means that

grain yield for continuous shallow

submergence can be achieved with 7-cm

irrigation water applied 3 d after disap-

pearance of ponded water, for a net

savings of 24% of the water requirement

(Table 2).

significantly affect yield, and 40 kg Nha

appeared sufficient. The interaction ofirrigation and N was not significant.

Applied N higher than 80 kg/ha did not

Table 2. Effect of irrigation schedule and N level on water requirement and water-use efficiency of summe

rice in Assam, India.

Rainfall (mm) Water requirement (mm) Water-use efficiency (kg/ha/mm)

1987 1988 1989 1987 1988 1989 1987 1988 1989 Mean

Treatment

Continuous sub- 504 1040 519 1304 1640 1149 1.71 0.83 2.30 1.61

7 cm water 504 1040 519 1204 1390 1009 1.66 1.14 2.71 1.84

mergence

1 DADPW

7 cm water 504 1040 519 924 1320 869 2.23 1.23 3.26 2.24

3 DADPW

Improving appliedphosphorus utilization byrice in Madagascar

J. R. Hoopper and J. Rabelolala, Ma-

dugascar-IRRI Rice Research Project

and FOFIFA Madagascar

On the Fe-toxic, low-P soils of theCentral Highlands of Madagascar,

broadcast P fertilizers are fixed by the Fe

and poorly utilized by the rice plant.

Resource-poor farmers often cannot

afford to apply the recommended

26 kg P/ha.

We compared applying 13 kg P/ha

(1/2 the recommended rate) by broadcast

and incorporation and by seedling root

dipping, in a farmers field in Manjakan-

driana (1,420 m) for 4 yr. Soil was 49%

clay, 21% silt, 30% sand, pH 4.9, and

had 3.31% organic C, CEC 10.2 meq,5.3 ppm available P.

Effect of P rate and method of application on yield of Chianan 8, transplanted on an Fe-toxic soil, Sambaina

Manjakandriana, Madagascar.

Yield b (t/ha)Treatmenta

1985/86 1986/87 1987/88 1988189 Mean

No fertilizer 2.5 d 0.8 c 0.9 c 1.1 d 1.4NK only 3.7 c 0.8 c 1.1 cNK + 13 kg/ha B/I 3.9 bc

1.6 c 1.81.3 b 2.3 b 2.2 b 2.4

NK + 13 kg P/ha root dipping 4.2 ab 2.0 a 3.0 a 2.6 a 3.0

NK + 26 kg P/ha B/I 4.4 a 1.4 b 2.4 b 2.2 b 2.6a B/I = broadcast and incorporated. N = 60 and K = 50 kg/ha. b In a column, means followed by a common letter are not significantl

different at the 5% level by DMRT.

Triple superphosphate (TSP) was and incorporating TSP, and root dipping

dissolved in water and soil was added with 13 kg P/ha was as effective as

until a sticky paste was formed (approxi- broadcasting and incorporating

mately 1:4:6 of TSP, water, and soil). 26 kg P/ha (see table). Leaf tissue

Seedling roots were coated in the paste analysis showed higher P levels in plants

and immediately transplanted. (The first fertilized by seedling root dipping.

year, rice roots were dipped in a mixture Concentrating the P around the roots

of water and TSP.) N and K were applied probably reduces the amount of P fixed

at 60 and 50 kg/ha, respectively. by the soil and makes more P immedi-

Averaged over 4 yr, root dipping was ately available to the rice plant.22% more effective than broadcasting

Integrated pest managementdiseases

Association of Fusarium

seeds and subsequent Seeds treated with 0.1% mercuricinfection in Pakistan chloride for 1 min and untreated seeds,

moniliforme Sheld. with rice incidence.samples from nine localities to assess its

400/sample, were studied. Twenty seeds

M. I. Ahmed and T. Raza, Plant Pathol-

per sterilized petri plate were plated onogy Department, University of Agricul- three layers of moistened blotter paper

ture, Faizalabad, Pakistan and kept at 25 C in 12 h light, 12 h dark

for 7 d. These seeds were examined

Rice bakanae disease caused by under a stereoscope; microscopic slides

Fusarium moniliforme Sheld.perfect also were studied for identification.

stage Gibberella fujikuroi Sawadais Other seeds from the same samples

becoming a serious threat to rice produc- were grown separately in sterilized pots,

tion in Pakistan. We collected rice seed and isolations from the vascular system

of the seedlings were made on Richard's

agar medium at 27 C. A third set of seed

was planted and typical bakanae disease

symptoms on the mature plants meas-

ured.

Seeds from all localities but D. G.

Khan showed the presence ofF. monili-

forme. Maximum presence of fungus onseeds was 19.75%. Nearly 20% of the

seeds treated with 0.1% mercuric

chloride from Gujranwala showed

presence of the fungus (see table).

When the seeds were not treated

before plating, highest fungus infection

was near 12% in those from Sialkot. In

most cases, fungus intensity was higher

IRRN 16:4 (August 1991) 19


21/26

in treated seeds, showing that the fungus Rice seeds from different localities showing percent bakanae disease infection in Pakistan.

was internally borne, or at least present

inside the seed coat.

Seedlings produced from the seed

samples confirmed the presence of

fungus in the vascular system. Bakanae

symptoms appeared on plants grown to

maturity.

Reisolation of the pathogen and back-

inoculation to other rice plants confirmedits pathogenicity.

Locality

Amin AbadDaska

G. G. KhanGujranwalaHafiz Abad

Kala Shah KakuNarang MandiSheikhupuraSialkot

Seeds a showingF. moniliforme (%) Seedlings showing Bakanae disease

F. moniliforme symptoms (%) inTreatedb Untreated in vascular system (%) plants grown fro

untreated seeds

9.5 6.2 10 66.0 1.5 6 70.0 0.0 0 0

19.8 9.5 17 811.0 7.2 12 7

12.2 5.5 10 98.8 1.8 9 11

11.5 7.2 13 1112.2 11.8 10 9

Effect of grain discolorationin upland rice on some yieldcomponents

E. Zulkifli, J. Klap, and J. Castano,

Sukurami Research Institute for Food

Crops, SARIF, P.O. Box 34, Padang

25001, West Sumatra, Indonesia

The main causal agents of grain discol-

oration (GD) in upland rice in West

Sumatra are different species of fungi,

with Helminthosporium oryzae being the

most important. Symptoms vary from

spots invisible to the naked eye to a

completely rotten endosperm. In suscep-

tible varieties, the disease can cause

complete yield loss.

We collected 50 panicles of suscep-

tible upland rice variety Tondano in the

Sitiung area and separated them into five

groups, with disease severities of 1, 10,30, 60, and 100%. Seeds of each severity

aMean of 4 counts.

bWith 0.1% mercuric chloride for 1 min.

group were planted in plastic trays (33

seeds/tray per replication) and grown in

the greenhouse, to determine the effect of

the disease on germination and plant

height. Additional panicles of each

severity group (3 panicles/replication)

were used to study the effect of diseaseon grains/panicle. Weight of 100 grains

was calculated for each severity group,

with three replications.

The higher the disease severity, the

lower the germination and seedling

height (see table). The disease reduced

germination as much as 40% and reduced

seedling height 3-20%. The higher the

severity, the more the empty grains/panicle, with parallel weight reduction.

Effect of rice grain discoloration on some yield components. a

~~ ~

Severity of grain Seedling Grains (no./panicle) Weight of Reductiodiscoloration Germinationb heightc 100 grainse in weigh

(%) (%) (cm) Filledd % Empty % (g) (%10)

1 92 a 10.9 (91) a 140 a 94 9 b 6 3.09 a

10 81 a 10.6 (86) a 137a 90 16 b 10 2.94 a 5

30 80 bc 10.2(79) a 135 a 91 14 b 9 2.95 a 4

60 73 c 9.7 (72) ab 101 b 74 35 a 26 2.56 b 17

100 52 d 8.7 (52) b 118 b 78 33 a 22 2.27 c 26

a

In a column, means followed by the same letter are not statistically different at a probability level of 0.05.

b

Av from 3 replication

panicles/replication.eAv from 3 replications, 100 seeds/replication.

33 seeds/replication.cAv from 3 replications. Values in parentheses are total number of seedlings.

dAv from 3 replications,

Integrated pest managementinsects

Duration of diapause in white 135-d variety, with IR64 (110 d) length-stem borer (SB) Scirpophaga ened the fallow period between dry andinnotata wet season crops to 3 mo. That favored

the white SB, which can aestivate as

S. Hendarsih, Sukamandi Research prepupae at the base of rice stubble. The

Institute for Food Crops, Sukamandi; and outbrea

Documents

International Rice Research Notes Vol. 16 No.4