International Rice Research Notes

March 1995The International Rice Research Notes (IRRN) expedites communication among scientists concerned with the development of improved technology for rice and ricebased 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.

Contents

Germplasm improvement Germplasm improvement

Genetics Analysis of yield and yield components in rice 4 General combining ability for kernel traits in rice 4 Evaluation of rice diallel crosses in semidry condition by combining ability analysis 5 Combining ability of some varieties for grain quality traits in diallel mating system 6 Breeding methods Heterosis for kernel characters in rice 7 High-yielding somaclonal variants of Basmati 370 7 Effect of regeneratlon media on shoot production from anther cultures of rice 8 A new source of thermosensitive genic male sterility for 2-line hybrid rice breeding 10 Effect of NAA and 2,4-D on plant regeneration from seedling leaf bases in indica rice 11 Grain quality Distribution of high density and low density grains in the panicle 12 A simple, low-cost, on-farm technique for accelerated aging of rice 12 Pest resistancediseases Development of near-isogenic lines as International differentials of the blast pathogen 13 Pest resistanceinsects Screening local varieties for resistance to whitebacked planthopper Sogatella furcifera in the Mekong Delta, Vietnam 14 Stress toleranceadverse temperature Influence of low night temperatures on rice spikelet differentiation in high-altitude swamps in Burundi 15 Stress toleranceadverse soils Aluminum uptake in relation to K, Ca, and P concentrations in the roots of two rice cultivars with different AI sensitivity 16

IRRN production team . . . . . . . . . . . .Editor: Carolyn Dedolph Assistant editor: Teresita Rola Layout and design: Ariel Paelmo Production Supervisor: Millet Magsino Editorial assistant: Luisa Gelisan Typesetting: Erlie Putungan Cecilia Gregorio Artwork. Juan Lazaro IV Jesus Recuenco

Integrated germplasm improvementirrigated IRRI rice hybrids evaluated at Kala Shah Kaku, Pakistan 17 Performance of commercial rice varieties in lowlands of western Venezuela 18 lntegrated germplasm improvementrainfed lowland Three rice varieties of medium duration released for rainfed lowland areas in Cambodia 18 Integrated germplasm improvementupland Jaldi Dhan: an extra early rice suitable for upland production Seed technology Seed technology for cold tolerance in rice 20 19

ISSN 0115-0944

Crop and resource management

Fertilizer management Potassium fertilizer for higher yields in scented rice Fertilizer managementorganic sources Green manure: a substitute for inorganic fertilizer N in lowland rice 22

Considering rice quality factors in farm management decisions 39 21News about research collaboration

Crop management Managing rice nurseries during winter season in the Hill Zone, Karnataka, India 23 Effect of planting date on grain yield and quality of semidwarf scented rice varieties 24 Integrated pest managementdiseases Comparison of Xanthomonas oryzae pv. oryzae strains from Africa, North America, and Asia by restriction fragment length polymorphism analysis 25 Relationship between DNA fingerprints and virulence of Pyricularia grisea from rice and other hosts in Korea 26 lntegrated pest managementinsects African rice gall midge pest in Sierra Leone 27

IRRI builds greenhouse for transgenic rice 40 Low-cost chopper turns farm residues into useful products 41 Cambodian farmers actively involved in technology testing 41 IRRI Library reaches out 41 Anaerobic seeding ready for farmer evaluation 41 Encouraging farmers to experiment with IPM 42 Climate changes and rice 42Announcements

lntegrated pest managementother pests Indian wild boar Sus scrofa L.: a rice pest in Madhya Pradesh, India 28 Effect of crop rotation and solarization on the population densities of rice root nematode Hirschmanniella spp. in Nepal 28 Farming systems Deepwater rice establishment in boro rice in the flood-prone ecosystem of West Bengal, lndia

1994-95 short course in rural development, project planning, and resource management 42 Biotechnologia Habana '95 42 New IRRI publications 43 Advanced courses from IHE 43 New publication 43 2nd International Symposium on Systems Approaches for Agricultural Development 43 Rice dateline 43 IRRI group training courses for 1995 43 Rice literature update reprint service 44 Call for news 44 IRRI address 44Instructions contributors Instructions for contributors

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Farm machinery Seeder developed for direct sowing of rice under the puddled soil surface 29 A low-cost chopper for farm byproduct use 30 Using rice hulls to fuel a portable gasifier-engine system 33Environment

Effect of climatic changes on rice production in Punjab, India 32 Rice ecosystems in Tanzania 33 Effects of temperature on host feeding in Cardiochiles philippinensis (Hymenoptera: Braconidae), a larval parasitoid of rice leaffolder Cnaphalocrocis medinalis 34Research methodology

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Detection of rice tungro bacilliform virus in nonvector insect species following genomic amplification 35 Modified method of gel consistency test with small samples 36 A simple method to assess the relative amount of leaf wetness in rice canopies 36 Inoculum efficiency in sheath blight as affected by contact frequency, leaf wetness regime, and nitrogen supply 38

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Germplasm improvementGenetics GeneticsAnalysis of yield and yield components in riceK. Ganesan, W. Wilfred Manuel, and T. Sundaram, Rice Research Station (RRS), Ambasamudram 627401, Tamil Nadu, lndiaGenetic parameters for 12 traits in very early inbreds and hybrids of rice. RRS, Ambasamudram, Tamil Nadu, India. 1993-94. Trait Mean (X) Standard deviation (SD) 0.85 14.35 1.80 2.24 24.83 0.21 3.74 8.08 0.06 0.44 0.22 0.35 Phenotypic coefficient of variation (PCV) 10.4 13.8 19.3 9.2 23.3 9.4 28.1 24.9 16.1 7.2 9.4 13.7 Genotypic Heritability (broad coefficient of variation sense) (GCV) (h 2 ) 10.4 13.7 19.1 9.1 23.3 9.4 28.0 24.9 15.8 7.1 9.1 13.5 98.8 99.0 98.4 97.7 99.6 99.6 99.5 99.9 95.9 97.1 94.7 96.7 Genetic advance as % of mean (GA%) 21.2 28.2 39.1 18.6 47.9 19.4 57.5 51.3 31.9 14.4 18.3 27.4

Mean and genetic variability are the important factors for selection. Heritability estimates and genetic advance are helpful in predicting the effects of selecting the best genotypes. We undertook this study to select good genotypes in very early rice cultivars and hybrids. Four early-maturing (105-115 d) varieties ADT36, ASD16, CO 37, and IR50, and seven very early-maturing (less than 100 d) rice varieties and cultures, ASD8, Heera, Kalyani II, Sattari, AS18696, and AS89011, were crossed in line tester mating design. The 11 parents and their 28 F1 hybrids were studied in an experiment laid out in a randomized block design, replicated three times, during 1993-94 late Pishanam season (Nov-Mar) at RRS. Observations were recorded on five randomly selected plants per replication. Mean (X), standard deviation (SD), phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability in the broad sense (h2 ), and genetic advance as a percentage of mean (GA%) were calculated for 12 traits. Significant differences were observed for all of the traits, indicating wide variability. PCV was, in general, higher than GCV, but the difference was very low, indicating less environmental influence on the expression of different traits. GCV ranged from 7.1 for kernel length to 28.0% for grain yield per plant (see table). Grains per panicle, grain yield per plant, and dry matter production exhibited high GCV and PCV, indicating a wide scope for improvement through selection. A moderate amount of variability (1020%) was observed for days to panicle emergence, plant height, panicles per

Days to panicle emergence Plant height Panicles per plant Panicle length Grains per panicle 100-grain weight Grain yield per plant Dry matter production Harvest index Kernel length Kernel breadth Kernel shape

66.7 104.6 9.4 24.6 106.7 2.22 13.4 32.46 0.42 6.17 2.39 2.58

plant, harvest index, and kernel shape, while low GCV was observed for panicle length, 100-grain weight, kernel length, and kernel breadth. All of the traits had very high heritability but only days to panicle emergence, plant height, grain yield per plant, dry matter production, harvest index, and kernel shape showed high h2 coupled with a high GA%,

indicating a predominance of additive gene effects in controlling these traits. Grains per panicle, grain yield per plant, dry matter production, and days to panicle emergence had high estimates of GCV, h 2 , and GA%. Direct phenotypic selection based on these traits would be effective for varietal improvement in very early rice cultivars.

General combining ability for kernel traits in riceP. Vivekanandan and S. Giridharan, Tamil Nadu Rice Research lnstitute (TNRRI), Aduthurai, India

We studied the general combining ability of five lines of high-yielding cosmopolitan varieties and three testers of Basmati varieties for kernel traits in a line tester mating design. The experiment was laid out in a randomized block design with three replications in 1991-92 wet season at TNRRI. Each treatment (parents and their resulting 15 F1 hybrids) was raised in two 3-m rows with 30- 20-cm spacing. We randomly measured 10 plants per replication from each treatment. Among the lines, Improved White Ponni and IR50 were good general combiners for kernel breadth, kernel length-breadth ratio, kernel length after

cooking, kernel breadth after cooking, and elongation index (see table). High general combining ability was recorded in Improved White Ponni for grain yield and linear elongation ratio, and in IR50 for kernel length. ADT37 had desirable general combining ability for breadthwise expansion ratio and elongation index, and ADT39 for grain yield and kernel breadth. Considering the testers, Pusa Basmati 1 was a good general combiner for six kernel traits, and ADT 41 for kernel length, kernel length-breadth ratio, and grain yield. High general combining ability effects are related to additive genetic effects that represent the fixable genetic component of variation. Improved White Ponni was determined to be the best parent, followed by Pusa Basmati 1, and IR50, which possess desirable general combining ability for the majority of kernel characteristics studied.

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IRRN 20:1 (March 1995)

General combining ability effects of parents for grain traits a at TNRRI, Aduthurai, India. 1991-92 wet season. Parent Grain yield (g) Kernel length (mm) Kernel breadth (mm) Kernel lengthbreadth ratio Kernel length after cooking (mm) 0.28* 0.80* 0.15* 0.96* 0.27* 0.06 Kernel breadth after cooking (mm) 0.18* 0.14* 0.06* 0.25* 0.14* 0.03 0.10* 0.15* 0.05* 0.02 Linear b elongation ratio Breadthwise c expansion ratio Elongationd index

Line TKM9 ADT37 ADT39 IR50 Improved White Ponni SE Tester ADT41 Pusa Basrnati 1 Kasturi

5.61* 2.23* 4.69* 2.62* 5.77* 0.83 4.39* 2.51* 1.88* 0.64

0.04* 0.52* 0.05* 0.64* 0.04* 0.01 0.16* 0.13* 0.04* 0.01

0.12* 0.22* 0.05* 0.16* 0.11* 0.01 0.003 0.04* 0.04* 0.01

0.20* 0.54* 0.02 0.58* 0.14* 0.01 0.08* 0.01 0.09* 0.01

0.09* 0.01 0.001 0.02 0.06* 0.01

0.01 0.07* 0.08* 0.03 0.02 0.01

0.06* 0.06* 0.05* 0.03* 0.03* 0.01

SE

0.05 0.26* 0.31* 0.05

0.03* 0.06* 0.03* 0.01

0.05* 0.04* 0.01 0.01

0.07* 0.08* 0.01 0.01

L-B ratio of cooked rice to mean L-B ratio of milled rice.

aSignificant at 5% level. b Ratio of mean length of cooked rice to mean length of milled rice. c Ratio of mean breadth of cooked rice to mean breadth of milled rice. d Ratio of mean

Evaluation of rice diallel crosses in semidry condition by combining ability analysisS. M. Ibrahim, Agronomy and Range Science Department, University of California, Davis, CA 95616, USA; and M. Subramanian, Rice Research Institute, Tamil Nadu Agricultural University, Tirur, Tamil Nadu, India

GCA and SCA effects across locations for grain yield and other traits. a Tamil Nadu, India, 1992 wet season. Parent/ hybrid GCA P1 P2 P3 P4 P5 P6 SCA P1/P2 P1/P3 P1/P4 P1/P5 P1/P6 P2/P3 P2/P4 P2/P5 P2/P6 P3/P4 P3/P5 P3/P6 P4/P5 P4/P6 P5/P6 GCA SE CD (5%) CD (1%) SCA SE CD (5%) CD (1%) Plant height Heading date Productive tillers Root weight Biomass Grain yield

Rice is grown on 2 million ha in Tamil Nadu, India. Only about 8% of this area is under limited irrigation, meaning that early drought is common. Drought warrants systematic research on developing rice varieties that withstand considerable moisture stress at early growth stages. We studied the general combining ability (GCA) of six parents: TKM9 (P1) and PMK1 (P3), improved droughttolerant varieties; AS26556 (P2), recently released early drought-tolerant variety; Poongar (P6), a traditional unimproved low-yielding local droughttolerant variety; and IR64 (P4) and ADT37 (P5), improved high-yielding varieties susceptible to drought. We also examined the specific combining ability (SCA) of 15 F1s of direct crosses in a 6 6 diallel design under semidry conditions during 1992 wet season. The experiment was laid out in a randomized block design with three replications in three locations: Agricultural College and Research Institute, Madurai; Agricultural Research Station,

6.28** 1.76** 9.08** 5.73** 0.40** 4.72**

0.40** 1.24** 5.28** 1.45** 7.35** 7.35**

0.30** 0.36** 0.01 0.74** 0.81** 0.81**

0.49** 0.45** 1.39** 1.13** 0.34** 1.01**

0.77** 2.01** 2.77** 1.33** 0.25 1.09**

0.54** 0.49** 0.41** 0.07 0.71** 0.71**

1.99** 1.00** 3.16** 2.33** 2.78** 3.36** 6.98** 0.37 0.91** 2.82** 2.84** 1.87** 0.20 1.29** 0.53**

0.03 0.68** 0.79** 0.71** 0.55** 2.60** 0.66** 3.02** 1.25** 1.26** 2.87** 2.35** 0.56** 1.94** 0.01

0.41* 0.93** 2.71** 0.99** 0.64** 1.95** 1.62** 1.92** 3.14** 1.32** 1.29** 1.81** 0.08 0.19 0.42

0.56* 0.87* 0.18 0.42* 1.14** 0.07 0.73** 1.01** 1.01** 1.07** 0.65** 0.06 0.07 1.82** 0.33

0.94 1.68** 0.37 1.25* 0.67 4.33** 2.00** 1.49** 1.49** 2.91** 0.18 0.01 3.17** 0.46 0.68

0.76* 1.04** 2.02** 0.39 0.14 4.74** 0.30 0.08 0.08 1.44** 0.50 0.60** 2.86** 1.33** 0.08

0.09 0.25 0.33

0.06 0.17 0.22

0.08 0.22 0.29

0.09 0.25 0.33

0.22 0.61 0.80

0.13 0.36 0.43

0.21 0.58 0.76

0.13 0.36 0.47

0.19 0.53 0.69

0.21 0.58 0.77

0.51 1.41 1.86

0.31 0.86 1.13

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

IRRN 20:1 (March 1995)

5

Paramakudi, and Cotton Research Station, Srivilliputtur, Tamil Nadu, India. The crop was directly sown and maintained under rainfed condition up to 45 d after sowing, at which time the crop was irrigated. Plots were 3-m rows with 15 plants each at 30- 20-cm row and plant spacing. Among the many physiological indices available, the most reliable, such as root weight and biomass productivity, were used to measure drought. Five competitive plants were randomly selected from each plot for observation and analysis.

Among the six parents tested, PMK1 (P3) was the superior general combiner for special drought characters (root weight, biomass productivity, plant height, and earliness). TKM9 (P1) for grain yield and IR64 (P4) for productive tillers were good general combiners. PMK1 (P3), a good combiner for all traits except grain yield and productive tillers, and IR64, a poor combiner for many characters, were crossed and showed positive significant SCA effects for all traits studied (see table). This shows that superior hybrids may also be obtained Ponni) and their 15 F1 hybrids obtained through diallel mating (without reciprocals) for combining ability of 10 grain quality traits. The experiment was laid out in a randomized block design during 1993 dry season and replicated three times. Hills were spaced at 20 10 cm, with a single seedling per hill. Five plants per replication were evaluated following standard procedures for 10 grain quality traits:

from high/low GCA parental combinations. After PMK1/IR64, hybrids AS26556 (good combiner)/PMK1 (good combiner) and TKM9 (medium combiner)/PMK1 (good combiner) were next in superiority. The differential combining ability of PMK1 with other parental types reveals that using this genotype as a potential parent in breeding programs to develop semidry-tolerant types may produce useful transgressive segregants in the segregating generation.

Combining ability of some varieties for grain quality traits in diallel mating systemK. Paramasivam, S. Giridharan, A. P. M. K. Soundararaj, P. Vivekanandan, and P. Parthasarathy, Tamil Nadu Rice Research Institute (TNRRI), Aduthurai 612101, India

We evaluated six popular high-yielding rice genotypes (IR50, TKM9, ADT37, ADT39, ADT40, and Improved WhiteTable 1. Analysis of variance for combining ability. Source of variation df

kernel length, kernel breadth, kernel thickness, L-B ratio, kernel length after cooking, kernel breadth after cooking, linear elongation ratio, breadthwise expansion ratio, hulling, and milling. The variances due to general combining ability (GCA) and specific combining ability (SCA) were significant except for kernel length. This indicated that the genotypes differed widely for the traits studied. Higher GCA variance than SCA

Mean squares Kernel length (mm) Kernel breadth (mm) Kernel thickness (mm) L: B Kernel length after cooking (mm) 0.368** 0.374** 0.002 Kernel breadth after cooking (mm) 0.094** 0.042** 0.001 Linear elongation ratio 0.011** 0.011** 0.001 Breadthwise expansion ratio Hulling (%) Milling (%)

General combining ability (GCA) Specificcombining ability (SCA) Error

5 15 40

0.205**a 0.005 0.016

0.205** 0.005** 0.001

0.046** 0.016** 0.001

0.378** 0.160** 0.001

0.018** 0.015** 0.001

3.874** 2.601** 0.002

4.037** 2.648** 0.011

a** = significant at 1% level.

Table 2. Estimates of general combining ability effects of parents for different grain quality traits. Parent Trait Kernel length (mm) Kernel breadth (mm) Kernel thickness (mm) L:B Kernel length after cooking (mm) 0.40** 0.14** 0.05** 0.07** 0.02 0.21** 0.014 Kernel breadth after cooking (mm) 0.03** 0.21** 0.04** 0.01 0.04** 0.11** 0.010 Linear elongation ratio 0.01** 0.06** 0.01 0.01 0.05** 0.02** 0.004 Breadthwise expansion ratio Hulling (%) Milling (%)

IR50 ADT37 TKM9 ADT39 ADT40 Improved White Ponni SE (gi)

0.09*a 0.18** 0.01 0.02 0.06 0.01 0.041

0.22** 0.15** 0.16** 0.05** 0.10** 0.14** 0.005

0.01** 0.02** 0.05** 0.07** 0.10** 0.10** 0.002

0.29** 0.32** 0.04** 0.15** 0.15** 0.07** 0.002

0.06** 0.02** 0.07** 0.02** 0.02** 0.03** 0.004

0.43** 0.37** 0.03** 1.19** 0.52** 0.64** 0.035

0.33** 0.70** 0.34** 1.08** 0.49** 0.63** 0.034

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

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IRRN 20:1 (March 1995)

variance for all the traits (except kernel length after cooking and linear elongation ratio) indicated the predominance of additive gene action (Table 1). IR50 possessed desirable GCA effects for kernel length, kernel breadth, kernel

thickness, L-B ratio, kernel length after cooking, kernel breadth after cooking, and linear elongation ratio. IR50 was found to be the best parent because of its desirable GCA effects for five traits (Table 2). ADT39 was the next best

parent. IR50 and ADT39 could be used in hybridization programs for improving grain quality traits through recombination breeding and for getting desirable segregants.

Breeding methods Breeding methodsHeterosis for kernel characters in riceP. Vivekanandan and S. Giridharan, Tamil Nadu Rice Research Institute (TNRRI), Aduthurai, India

Relative heterosis (di) and heterobeltiosis (dii) in % for kernel characters in selected crosses. a TNRRI, Aduthurai, India. 1991-92 wet season. Kernel length after cooking di 2.7* 1.4 2.8* 12.5** 13.2** 3.6* dii 16.6** 14.2** 11.2** 4.4** 3.6** 9.9** Kernel elongation di 9.2** 4.0** 8.8** 12.2** 11.9** 8.0** dii 5.2** 3.3* 8.8** 11.5** 11.9** 7.3**

Kernel length Cross ADT37/ADT41 ADT39/ADT41 ADT39/Kasturi IR50/Kasturi Improved White Ponni/ADT41 Improved White Ponni/Kasturi di 3.1** 1.9** 2.6** 0.7* 1.9** 1.2** dii 22.1** 17.2** 16.0** 5.6** 14.7** 15.5**

Kernel L:B ratio di 11.4** 6.8** 11.5** 5.1** 4.1** 9.2** dii 36.9** 26.0** 29.3** 15.6** 21.5** 25.2**

Information is limited on the extent of heterosis for kernel characters in rice. We studied the heterotic manifestations of four kernel characters in 15 hybrids involving eight parents. The experiment was laid out in a randomized block design with three replications during 1991-92 wet season (Oct-Feb) at TNRRI. Each genotype (parents and hybrids) was planted in two 3-m rows at 30- 20-cm spacing. Observations were recorded for 10 randomly selected plants per replication. Seeds were hulled in a McGill sample sheller. Kernel length and L-B ratio were measured with a Mitutoyo micrometer. Grain was milled in a Kett rice polisher and cooked by the method of Juliano and Perez. Kernel elongation was computed as the ratio of mean length of cooked rice to that of milled rice. The performance of hybrids over mid-parent (di) and better parent (dii) was estimated following standard procedures. Heterosis for kernel length was low. Improved White Ponni/ADT41 and IR50/Kasturi expressed significant and positive relative heterosis. Heterosis for kernel L-B ratio was significant and negative, indicating that none of the hybrids were superior for grain fineness. Relative heterosis for kernel length after cooking was positive and significant in five crosses. Heterosis over mid-parent and better parent for kernel elongation was positive and highly significant in six hybrids (see table).

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

IR50/Kasturi and Improved White Ponni/ADT41 show promise for improving kernel length, kernel length after cooking, and kernel elongation through heterosis breeding.

High-yielding somaclonal variants of Basmati 370F. M. Abbasi, S. T. Abbas, and M. A. Sagar, Rice Program, National Agricultural Research Centre (NARC), P. O. NIH, Park Road, Islamabad 45500, Pakistan

Improving basmati varieties through cross breeding results in recombination of various genes for yield and quality. But

these new combinations often do not yield the desired basmati quality. We have been researching ways to accelerate the improvement of both quality and yield of basmati rices. We obtained a series of somaclonal variants with desired characteristics. Seeds of Basmati 370 were inoculated on MS medium with 2 mg 2,4-D/liter. Calli were subcultured 12 times on the same

Table 1. Agronomic performance of somaclonal variants. a NARC, Islamabad, Pakistan. Variant Flowering (d) 114 de 127 b 129 ab 115 de 116 cd 113 e 116 cd 118 c 114 de 130 a 2.142 1.05 Plant height (cm) f 120 c 140 147 b 116 g h 113 e 123 d 127 e 123 122 e 150 a 2.187 0.99 Tillers/ hill (no.) 12 e 14 cd 14 cd 15 bc 13 de 13 de 20 a 16 b 15 bc 9 f 1.265 5.23 1,000-grain weight (g) 17.33 cd 16.00 de 14.33 e 13.67 e 19.00 abc 17.67 bcd 17.33 cd 16.00 de 21.00 a 20.00 ab 2.38 8.08 Fertility (%) 89.0 a 65.0 de 65.0 de 63.3 de 70.0 c 65.0 de 66.3 cd 61.7 e 80.0 b 70.0 c 3.514 2.95 Yield (t/ha) 5.0 a 3.0 bc 2.5 cd 2.1 d 3.5 b 3.5 b 3.2 b 3.1 bc 5.2 a 3.5 b 0.5868 9.90

TF4 SN85 SN1-80 TF11 SN12 TF8 TF9 TF10 Basmati 385 Basmati 370 LSD (5%) CV (%)

a Means in a column followed by the same letter are not significantly different at 5% level by DMRT.

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Table 2. Grain quality characteristics of TF4 and Basmati 370. NARC, Islamabad, Pakistan. Genotype Head rice (%) 55.4 55.6 Kernel Length (mm) 6.9 6.7 Breadth (mm) 1.73 1.70 Thickness (mm) 1.55 1.60 Quality index L:BT 2.6 2.5 Kernel Size Long Long Shape Slender Slender Type Fine Fine

TF4 Basmati 370

MS medium, with a 15-d interval between subcultures. Three hundred 3-mm calli were transferred to LS medium for regeneration. Plants regenerated were termed R0 plants. Seeds collected from these plants

were the source of R1 plants, and R2 plants were raised from seed collected from R1 plants. About 60% of the lines differed from the parental variety. Eight R2 lines (TF4, TF8, TF9, TF10, TF11, SN12, SN85, and SN1-80) were early

flowering, stiff stemmed, short, and had acceptable grain appearance. They were evaluated in the field for agronomic performance. Results indicated that plant height and days to flowering were reduced significantly compared with those of Basmati 370. TF4 was the most promising variant (Table 1). This line had comparatively greater grain length than Basmati 370 (Table 2). TF8, TF9, and SN12 yielded at par with Basmati 370. Somaclonal variants produced through tissue culture may be used as additional sources of interesting variability for rice breeding.

Effect of regeneration media on shoot production from anther cultures of riceN. M. Ayres, Biochemistry and Biophysics Department, Texas A&M University, College Station, TX 77843-2128, USA; and A. M. McClung, Texas A&M/USDA Agricultural Research and Extension Center, Beaumont, TX 77713, USA; G. A. Walker and W. D. Park, Biochemistry and Biophysics Department, Texas A&M University

Plants produced from 11 crosses on 4 regeneration media. Crossa Total (no.) (%)b no. N6NB % MSNBC no. % MSMU no. % MSCIB no. %

To identify a medium that could be used on crosses between a wide variety of rice (Oryza sativa) cultivars, we investigated the ability of four regeneration media to induce shoots from antherderived calli. Panicles were selected from F1 plants of 11 crosses of cultivars and breeding lines at the Texas A&M/ USDA Agricultural Research and Extension Center, Beaumont, Texas, USA. Parents included the US longgrained javanica rice cultivars Cypress, Jodon, L202, Lemont, and Toro-2 and the Chinese indica cultivar Teqing. Three unreleased US breeding lines were also used, including javanica line 90102065, indica line MB231, and MB302, derived from an indica japonica cross. Panicles containing microspores at the early- to mid-uninucleate stage were collected from field-grown plants and were kept at 6-8 C in the dark for 3-4 d. They were sterilized with 40% bleach for 16 min, followed by three sterile water washes. Anthers were then removed from the florets, placed on callus induction medium, and incubated

CPRS/MB231 Anthers Calli Shoots CPRS/Toro-2 Anthers Calli Shoots Jodon/Toro-2 Anthers Calli Shoots L202/MB231 Anthers Calli Shoots L202/TQNG Anthers Calli Shoots L202/Toro-2 Anthers Calli Shoots LMNT/Toro-2 Anthers Calli Shoots TQNG/MB231 Anthers Calli Shoots TQNG/Toro-2 Anthers Calli Shoots 2065/MB231 Anthers Calli Shoots 2065/MB302 Anthers Calli Shoots All crosses Anthers Calli Shoots

5730 543 15 5600 727 20 6685 1506 9 3360 275 14 5535 668 4 8230 2345 20 7430 2021 15 10,815 600 58 6950 1937 60 2750 197 10 5125 205 16 68,210 10,960 221

9.5 2.8 13.0 2.8 22.5 0.6 8.2 5.1 12.1 0.6 28.9 0.9 27.2 0.7 5.6 9.7 27.9 3.1 7.2 5.1 4.0 7.8

138 0 203 5 547 0 40 0 212 0 821 4 785 0 213 9 486 3 -

0

200 4 274 9 503 0 102 10 254 1 819 12 732 8 184 23 777 32 115 4 94 2

2.0

148 11 166 6 310 7 75 3 137 3 377 2 315 5 138 20 504 20 82 6 111 14

7.4

57 0 84 0 146 2 60 1 65 0 328 2 189 2 65 6 170 5

0

2.5

3.3

3.6

0

0

0

2.3

1.4

0

9.8

4.0

1.7

0

0.4

2.2

0

0.5

1.5

0.5

0.6

0

1.1

1.6

1.1

4.2

12.5

14.5

9.2

0.6

4.1

4.0

2.9

3.5

7.3

-

2.1

12.7

16.1 2.0

3445 21

0.6

4023 92

2.3

2328 90

3.9

1164 189

1.5

a CPRS = Cypress, TQNG = Teqlng, LMNT = Lemont. bCalculated as percentage of anthers forming calli and percentage

of calli forming shoots.

8

IRRN 20:1 (March 1995)

at 25 C in the dark for 1-2 mo. The callus induction medium consisted of Chus (N6) salts and vitamins, 60 g sucrose, 0.5 g casein hydrolysate, and 2 mg 2,4-D per liter. When calli had developed to 1-2 mm in diameter, they were randomly placed onto one of four regeneration media. Medium N6NB was Chus basal salts supplemented with 0.1 g inositol, 30 g sucrose, 2 mg benzyl adenine (BA), and 0.005 mg naphthalene acetic acid (NAA) per liter of medium. The other three media were comprised of MS salts, 0.1 g inositol, and 30 g sucrose per liter. In addition, MSMU and MSNBC contained MS vitamins (0.5 mg nicotinic acid, 0.5 mg pyridoxine-HCl, 1 mg thiamine-HCl, and 2 mg glycine per liter). MSCIB was supplemented with 0.8 mg BA, 0.5 mg indole acetic acid (IAA), and 0.5 g casein hydrolysate. MSMU was supplemented with 1 mg BA, 0.5 mg IAA, and 0.5 g casein hydrolysate. MSNBC was supplemented with 2 mg BA, 0.5 mg NAA, and 1 g casein hydrolysate. All media were adjusted to a pH of 5.7 and were solidified with 4 g of agarose per liter. Calli on regeneration media were cultured at 25 C under 16 h light, 8 h dark and were transferred to fresh media every 2-3 wk. Shoots were transferred to basal MS medium with 3% sucrose for rooting when they were several centimeters long, typically 4 wk after calli were placed on regeneration medium. Calli with green spots were maintained on regeneration medium for up to 2.5 mo to allow for shoot production; most shoots, however, were obtained within 4-6 wk. Once a vigorous root system developed, plants were transferred to soil. All green shoots but one grew into mature plants when transferred to the field. The 68,210 anthers plated produced 10,960 calli (1 6.1 %) which were randomly placed onto four types of regeneration media (see table). Overall, 221 of these calli (2.0%) produced green shoots and 586 (5.3%) produced albino shoots. However, as observed in other studies, the rate of green shoot formation differed among media as well as among genotypes. With MSMU, 3.9% of the calli formed green shoots, compared with

0.6% for N6NB. 1.5% for MSCIB, and 2.3% for MSNBC. The superior performance of MSMU was because of better production of shoots from most of the crosses rather than from being skewed by a few crosses producing many shoots. Data in the table are listed by number of independent calli producing green shoots rather than by total number of shoots produced to eliminate bias from crosses producing many shoots per callus. Eight of the 11 crosses tested performed best on MSMU, and one produced equal numbers of shoots on MSMU and MSNBC (see table). Only two crosses produced more shoots on MSNBC; L202/ MB231 and L202/Toro-2. This might be attributed to L202 performing better on this medium. L202 was also a parent in another cross that performed better on MSMU than on MSCIB. Many albino shoots were also produced on all four media (data not shown). Many of them resulted from crosses involving Teqing, possibly reflecting the large genetic distance between the indica Teqing and the other cultivars. While most calli produced no shoots, those that did had an average of 4.3 green shoots per callus, with no apparent difference between the four media. Plants derived from seed of multiple plants taken from a single callus had very similar phenotypes in the field while the phenotype differed among plants derived from different calli (see figure). We did not appear to obtain chimeric calli, perhaps because of calli being

~

Field view of some of the anther culturederived plants. Every 4 rows are from seed of a single independent plant.

placed on regeneration medium when they were only 1-2 mm in diameter. Overall, MSMU gave a 2-7-fold greater rate of regeneration from calli than did the other media tested for a wide range of cultivars and breeding lines. For the crosses tested, this corresponded to 2-11 calli that produced one or more green plants per 1,000 anthers plated (av of 6). Thus MSMU should be a generally useful regeneration medium for rice anther culture.IRRN REMINDER

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 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 internationally known check or control treatment.

IRRN 20:1 (March 1995)

9

A new source of thermosensitive genic male sterility for 2-line hybrid rice breedingP. V. Satyanarayana, I. Kumar, and M. S. S. Reddy, Genetics and Plant Breeding Department, College of Agriculture, Andhra Pradesh Agricultural University, Rajendranagar, Hyderabad 500030, India

Table 1. Pollen fertility-sterility behavior of male sterile mutant rice line under field and glasshouse conditions. Hyderabad, India, 1990. Flowering date 7 Nov 8 Nov 9 Nov 10 Nov 11 Nov 12 Nov 13 Nov 14 Nov 15 Nov 16 Nov 17 Nov 18 Nov 19 Nov 20 Nov 21 Nov-14 Dec Swarna (MTU7029) (control) 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Pollen sterility (%) Field (20.1/30.8) a (20.2/30.9) (19.8/30.7) (18.9/30.9) (18.6/30.6) (18.4/29.3) (18.1/29.3) (18.2/28.2) (18.1/27.5) (18.2/27.3) (18.5/27.5) (18.3/26.5) (18.0/27.8) (17.8/27.9) (