international rice research notes vol.22 no.2

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

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 three times a year in April, August, and December by the International Rice Research Institute.

The IRRN is a mechanism to help scientists keep each

Focus on rice genetics The specter of food shortages is looming once again, with the annual rate of increase of rice production slowing to where it is lower than the rate of increase of rice consumers.

rice have come perhaps in the nick of time to provide us with new tools to develop rice varieties for the future. Only 10 years ago, the status of rice genetics was considered far behind that of other food crops, such as maize and wheat. The past decade, however, has seen an explosion of knowledge in this arena. Rice is now considered a model plant for such research on cereal crops.

In October 1995, IRRI hosted the Third International Rice Genetics Symposium. More than 500 scientists from 31 countries attended. Along with a dramatic increase in the attendance over the years has come a major shift in the complexion of the program. During the first symposium in 1985, around 90% of the papers were on classical genetics; at this symposium, about 80% of the papers addressed topics on cellular and molecular genetics.

IRRI book. The posters displayed at the symposium appear as notes (in a modified format) throughout this issue of IRRN. They are denoted by the symbol.

information.

Recent advances in cellular and molecular genetics of

The key papers presented have been published as an

We hope you find these notes to be a valuable source of

IRRN production team ........................................... Editor: Domenic Fuccillo Assistant editor: Teresita Rola Layout and design: Erlie Putungan Artwork: Erlie Putungan

Contents Volume 22, No. 2, 1997

Genetic resources ITS1 sequences of nuclear ribosome DNA in rice species from China

and their phylogenetic implications 4 Quantitative trait locus analysis of trait variation among annual and

perennial ecotypes of Oryza rufipogon 4 Determination of chromosome numbers of wild Oryza species

conserved in the International Rice Genebank at IRRI 5

Genetics Genetics of protein per grain in rice 6 The relationship between the morphological fertility of pollen and

marker gene Est9 6 Correlation and heritability of grain and leaf characters in indica rice

in high yield-conducive environments of Yunnan, China 7 Heterosis: early prediction and relationship with reproductive

phase 8

Breeding methods Callus induction and plant regeneration from anther culture of six

Long days slow down panicle development of late rice strains 10 Rice varieties of Kerala as restorers and maintainers for wild

Machhapuchhre 3 (MP3), the first rice variety developed through a

high-yielding indica/basmati crosses 9

abortive cytoplasmic male sterile lines 11

participatory plant breeding approach released for mid to high altitudes of Nepal 12

Breeding of Zi-Biao S line, the indica photothermosensitive genic male sterile line with recessive purple leaf marker 12

High-frequency plant regeneration in wild species of Oryza 13 Anther culture of indica/Basmati rice heterotic F 1 and F 2 hybrids and

selection of desirable double haploid lines 14 Evaluation of rice hybrids in varying environments 15 Combining ability of rice cultivars with IRRI-bred cytoplasmic male

Callus induction from indica rice coleoptiles 17 Identification of thermosensitive genic male sterile (TGMS) lines in

Floral traits influencing outcrossing rate in rice 18 Parag 401, a semidwarf rice variety developed through anther

sterile lines 16

rice germplasm 18

culture 19

Grain quality Grain quality of some Basmati genotypes 20

A method of producing Basmati rice aroma from Bassia flowers 21 Effect of degree of polish on physical and gravimetric properties of

Effects of genotype × soil interaction on rice grain quality in japonica

Physicochemical properties of japonica and indica waxy rice 20

rough rice 21

rice 22

2 IRRN 1997

Germplasm improvement

Yield potential Crop management An assessment for yield estimation in upland rainfed ecosys- Effect of foliage pruning on performance of rice under semi-deep

tem of Bastar Plateau Zone, Madhya Pradesh 23 water situations (50-100 cm) 36 Effect of seed rate, seed density, and nitrogen fertilizer on per-

Pest resistance—diseases formance of flood-prone lowland rice 37 GPIR-22: a gene pool developed to improve partial resistance Effect of tillage and fertilizer levels on grain yield and incidence of

to blast of upland rice 24 brown spot disease in rice 38

Pest resistance—insects Intensity of the attack of Sitotroga cerealella (Olivier) in rice

genotypes and its effect on seedling emergence 25 lndur Samba-a super fine-grain, short-duration, gall midge-

resistant rice variety 26

Stress tolerance—adverse soils Screening for tolerance for iron toxicity 26

Integrated germplasm improvement—upland Yumenohatamochi, a new upland rice variety in Japan 27

lntegrated germplasm improvement—irrigated ASD20: a new short-duration rice variety for Tamil Nadu,

India 28

Integrated germplasm improvement—flood-prone Padmanath: an improved deepwater rice in Assam,

Panindra: a new deepwater rice for Assam, India 29 Ranjini (MO 12): a high-yielding rice variety with blast and brown

India 28

planthopper resistance 29

Seed technology On-farm seed priming to accelerate germination in rainfed, dry-

seeded rice 30

lntegrated pest management—diseases Effect of submergence of rice plants on the development of sheath

Effect of crop growth stage and N level on leaf blast monocyclic

Variation in isolates of Sclerotium oryzae, the rice stem rot

blight 39

parameters on a new rice plant type 40

pathogen 41

Integrated pest management—insects Insecticide susceptibility of brown planthopper Nilaparvata lugens

in the lower Yangtze Valley 41 Effect of rice armyworm Mythimna separata (Walker) on grain yield

of rice 43 Predation of Chilo suppressalis (Walker) eggs by the black cricket

Metioche vittaticollis (Stål) 43 Bioassay of Fusarium pallidoroseum (Cooke) Sacc., (Deutero.

mycotina: Hyphomycetes) against leaffolder 44

Integrated pest management—other pests Evolving patterns of rat control at IRRI 44

Farming systems Fertilizer management on two contrasting soil types in the rainfed

Establishment of wheat following lowland rice in east India 46 lowland rice production system in Cambodia 45

Postharvest technology Stripper harvesting improvements meet Chinese needs 46

Plant physiology Growth response of diverse rice genotypes to exogenous

application of GA 3 31 A rapid method of isolation of genomic DNA from filamentous

Physiology and plant nutrition Method for detecting rice sheath blight pathogen in soil samples Effect of low light stress on photosynthesis, dry matter pro- using mungbean 48

fungi 47

duction, and grain yield in rice hybrids bred from two DNA fingerprinting of bacterial blight pathogen directly from infected different cytoplasmic male sterile sources 32 leaves 49

varieties 33 yellow stem borer 50 Estimation of elongation efficiency in deepwater rice A method for estimating the number of eggs in egg masses of

Histological variation among aromatic rice 33 Excel modeling environment: description and application to the ORYZAO model 51

Fertilizer management—inorganic sources Preliminary studies on response of a rice-based crop sequence

to S and Zn in temperate Kashmir, India 34 Fukui International Koshihikari Rice Prize 52

Fertilizer management—organic sources Effect of organic and inorganic fertilizers on sustainability of

soil fertility and grain yield in a rice - wheat system 35

Crop and resource management

Research methodology

Announcement

Vol. 22, No. 2 3

Germplasm improvement

ITS1 sequences of nuclear ribosome DNA in rice species from China and their phylogenetic implications

Yi Zhou, Yu-Ping Zhou, De-Yuan Hong, Laboratory of Systematic and Evolutionary Botany, Chinese Academy of Sciences (CAS), 100093 Beijing, China; Bao-Rong Lu, IRRI; Xue- Qian Gong, and Shou-Yi Chen, Laboratory of Plant Biotechnology, Institute of Genetics, CAS

This study assessed the capability of using internal transcribed spacer (ITS1) sequences for reconstructing the phylo- geny of rice species from China. Three accessions of wild and two accessions of cultivated rice were used (Table 1). Total DNA was extracted from leaf samples following the procedures described by Tai and Tanksley (1990). Polymerase chain reaction (PCR) amplifications were performed in 50 µL volumes containing 100 ng DNA template and 2.5 µL Taq polymerase. A PE-

Table 1. Oryza species included in this study,

Accession Taxon Genome number

1 O. sativa ssp. indica AA 2 3

O. sativa ssp. japonica AA O. rufipogon AA

5 O. officinalis CC 6 O. granulata Diploid

480 thermal cycler was used under the following conditions: 35 cycles of 94 °C for 1 min, 57 °C for 1 min, and 72 °C for 1 min. PCR-amplified DNA products were recovered, complemented, and then cloned into the vector pUC 118 with standard protocols. Sequencing of ITSl was conducted on an AB1 373A automated sequencer using a TaqDye Primer Cycle Sequencing Kit (ABI). The ITSl sequences of the five taxa together with a published rice sequence (Takai- wa et al 1985) were aligned with the Clustal V program. The data matrix was analyzed using UPGMA with Jukes-Cantor distance and Neighbor- Joining with Kimura 2-parameter distance of the MEGA version 1.02 (Kura et al 1993).

species and two subspecies of cultivated rice showed diversity in size from 193 bp ( Oryza rufipogon ) to 218 bp ( O. granulata ) (Table 2). To date, these ITS1 sequences were the shortest

The ITS1 sequences of the three wild

Origin Voucher specimen

China Yunnan, China Guangxi, China Zhou Yi 940135 Hainan, China Zhang Shou-zhou 940130 Yunnan, China Gao Li-zhi 940208

Table 2. Size and G+C content of ITS1 sequences of six rice accessions.

Accession Taxon Sequence G+C number size content

(bp) (%)

1 O. rufipogon 193 72.7 2 O. sativa ssp. indica 194 72.3 3 O. sativa ssp. japonica 194 72.3 4 O. sativa 194 72.3 5 O. officinalis 194 72.3 6 O. granulata 218 69.3

a From Takaiwa et al 1985. Plant Mol. Biol. 4:355-364.

among angiosperms studied, except for O. granulata. Percentage of G+C contents of the five taxa ranged from 69.3% to 72.2% (Table 2), and the G+C contents are the highest in angiosperms examined so far. The alignment of the ITS1 sequences, using O. rufipogon as a standard, yielded 223 characters with 116 (52.0%) identical sites for all sequences and 107 (47.9%) variable sites, of which 28 sites (12.6%) were phylo- genetically informative.

Based on analysis of ITS1 sequences, this study suggests that O. granulata has a distant relationship with other Oryza species. Because the relationships of the rice species used in this study agree with those generated from other studies, ITS1 may be considered a useful tool for addressing phylogenetic questions in the genus Oryza.

Quantitative trait locus analysis of trait variation among annual and perennial ecotypes of Oryza rufipogon

J. R. Kohn, University of California at San Diego(UCSD),9500 Gilman Drive, La Jolla, CA 92093-0116, USA; N. Leyva, Centro de Investigaciones de Estudios Avanzados del IPN (CIEA), A. P. 629, Irapuato, Gto., Mexico; R. Dossey, UCSD; O. Paredes, CIEA; B. Sobral,

Center for Application of Molecular Biology for International Agriculture (CAMBIA) Americas, 11099 N. Torrey Pines Road, Suite 209, La Jolla, CA 92037, USA; and H. Morishima, National Institute of Genetics, Mishima, Shizouka-ken 411, Japan

Quantitative trait locus (QTL) analysis was conducted to study variation among annual and perennial ecotypes of Oryza rufipogon, the wild progenitor of rice. The 101 F2 offspring analyzed resulted from a cross between a single

annual and a single perennial plant regenerated from seeds collected in Bangkok, Thailand. Each F 2 genotype was split into two clones grown on adjacent short-day plots at Mishima, Japan, during the summer of 1994, and traits measured (see table). Several measurements were combined to cap- ture the tendency toward annuality or perenniality, such as the ratio of panicles to tillers (high in annuals and low in perennials). Broad-sense heritability of each trait was calculated using an

4 IRRN 1997

Genetic resources

- -

a

ANOVA model. Each genotype was Single and multiple regressions of markers on traits. Underlined traits are those for which the annual ecotype

scored for 40 molecular markers single expresses larger values (see references in Morishima et al 1992, Oxford Surv. Evol. Biol. 8:135-184).

and multiple regression was used to Trait Marker Chromosome R 2 p a R 2 g b

estimate the proportion of phenotypic variation. Genetic variation explained by markers was estimated by dividing the phenotypic R 2 by the broad-sense heritability of each trait.

Broad-sense heritability of traits ranged from 0.81 to 0.37. Negative genetic correlations were found between most measures of fertility and vegetative persistence. Single QTL explained up to 27% of the phenotypic variation in the traits examined (see table). Multiple regressions explained from 7 to 38% of the phenotypic and from 18 to 62% of the genotypic variation in each trait. Some QTL appear to explain significant propor- tions of variation in several traits, suggesting pleiotropic effects. Marker G1184Ca is apparently linked to a QTL controlling the proportion of tillers that flower while having a negative pleiotropic effect on vegetative persistence. If this QTL is confirmed in further studies, it will represent a genetic locus that underlies the life history trade-off between reproduction and survival.

studies which have found chromo- somal regions controlling large frac- tions of the phenotypic variation. We found only one case in which more

Our results contrast with recent QTL

Determination of chromosome numbers of wild Oryza species conserved in the International Rice Genebank at IRRI

Bao-Rong Lu, Ma. E. B. Naredo, M. Macatangay and Ma. T. Alvarez, IRRI

To date, more than 3,000 wild rice accessions, representing 21 species of Oryza and 11 related genera, are being conserved in the International Rice Genebank (IRG) at IRRI. The chromosome number of each conserved accession of different Oryza species, which should be part of the passport data, is essential to facilitate charac- terization and species identification.

Heading date G1184Ca G1082 Multiple regression

Anther length RZ58 G200 G127 G181 Multiple regression

G1184Ca Height C86

C342 G56 Multiple regression

RZ58 Multiple regression

C196 G1085 Multiple regression

C596 Multiple regression

Panicles tlller -1 G1184Ca

Panicle length G1184Ca

Spikelets panicle -1 G56

Regeneration index G1082

1 10

2 6

10 11

1 1 6 8

1 2

1 2 9

8 7

10

0.135 0.068 0.180 0.108

0.085 0.080 0.383

0.105

0.091 0.097 0.079 0.071 0.255 0.271 0.142 0.304 0.062 0.118 0.078 0.246 0.060 0.062 0.102 0.066

0.175

0.234 0.133 0.129 0.105 0.099 0.473

0.179 0.146 0.131 0.472 0.553 0.290 0.620 0.124 0.235 0.156 0.492 0.110 0.114 0.189 0.179

0.089

0.168

Postharvest tillers/ preharvest tillers G1184Ca 1 0.086

C86 0.210

1 0.064 C397 9

0.156 0.070

C196 0.170

2 0.087 0.212 Multiple regression 0.253 0.616

Postharvest panicles/ postharvest tillers G1184Ca 1 0.168 0.271

a R 2 p = phenotypic R 2 . b R 2 g = genotypic R 2 . calculated as R 2 p × H 2 .

than 25% of the phenotypic variation in ferentiation in O. rufipogon, therefore, a trait is explained by a single marker. may be more polygenic than species Ecological adjustments that contribute differences examined in previous to intraspecific annual × perennial dif- studies.

Number of accessions in each Oryza species for which chromosome number has been determined.

Species Accessions (no.) Chromosome number Source

O. australliensis 17 24 O. barthii 141 24 Africa

Australia

O. brachyantha 11 24 O. elchingeri (diploid) 14 24

Africa

O. glumaepatula 37 24 Africa, Asia

O. granulata South America

O. longistaminata 4 24 Asia Africa

O. meridionalis 35 24 O. nivara

Australia 215 24

O. officinalis (diploid) 136 Asia

24 O. rufipogon 31 24

Asia

O. sativa f. spontanea Asia

1 24 O. alta 6 48

lndonesia South America

O. eichingeri (tetraploid) 4 48 O. grandiglumis

Uganda, Sri Lanka 9 48

O. longiglumis South America

5 48 O. minuta

Indonesia, Papua New Guinea

O. officinalis (tetraploid) 2 48 Philippines

O. punctata (tetraploid) 1 48 India

O. ridleyi Kenya

7 48 Total

Southeast Asia

18 24

48 48

742

Vol. 22, No. 22 5

Genetics of protein per grain in rice

S. Geetha and A. Ayyamperumal, Sugarcane Research Station, Sirugumani 639115, Tamil Nadu, India

Seed protein content is usually expressed as percent brown (dehulled) rice protein (BRP). This trait is highly influenced by environment and, hence, its expression is complex. It has been suggested that instead of considering BRP, it would be effective to use as selection criterion the actual protein

available per grain (PPG) since the latter is less influenced by environment. However, information on inheritance patterns of PPG in rice is scanty.

We studied gene action and estimated general combining ability (GCA) using six parents (IR50, ADT37, ADT41, Duansan, TKM6, and ADT39) and 30 hybrids generated through full diallel mating.

The experiment was laid out in a randomized block design with three replications during the 1993 dry season. Each genotype (parents and hybrids) was planted in three rows of 3 m length and in 30- × 20-cm spacing in a field fertilized with 120 kg N ha -1 , 26.4 kg P ha -1 , and 49.8 kg K ha -1 . Observations were recorded for five randomly selected plants per replication.

A total of 100 fully filled, healthy grains from each plant were randomly sorted out and their weights recorded. Ten grains were taken randomly, dehulled manually, and ground to fine powder. Each sample was analyzed by the standard micro-Kjeldahl method to obtain %N. The BRP content was derived by multiplying %N by 5.95. The PPG (mg) was estimated as [%BRP × 100-grain weight (g)×10].

The analysis of variance for GCA clearly indicated the importance of

both additive and nonadditive genetic variance (see table). The higher values (>0.5) of predictability ratios also revealed the preponderance of additive genetic variance. The additive genetic variance could be effectively used by simple pedigree method of breeding.

Among the six parents, IR50, ADT37, and ADT41 were found to be the best, and they could be used in hybridization programs to improve PPG.

The relationship between the morphological fertility of pollen and marker gene Est 9

Lu Chuangen, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; K. Takabatake and H. Ikehashi, Faculty of Agriculture, Kyoto University, Kyoto 606-01, Japan

Many indica-japonica hybrids exhibit a low seed set. In cases where female gamete fertility is normal, the lowered seed set can be attributed to pollen sterility. To use the strong heterosis of indica-japonica hybrids, we must overcome the barrier of pollen sterility.

We analyzed genes for pollen hybrid sterility in F 2 populations from three- way crosses of Akihikari //IR36/

We have been observing chromosome preparations of root tips and pollen mother cells to determine the chromosome number of IRG wild rice accessions. To date, 742 accessions representing 18 wild Oryza species have been cytologically examined. Our observations (see table) revealed that, in general, chromosome numbers in the wild Oryza species were constantly 2n=2x=24 in the diploid species O. australiensis, O. barthii, O. brachyantha, O. glumaepatula, O. granulata, O. longistaminata, O. meridionalis, O. nivara, O. rufipogon, O. sativa f. spontanea, and in the majority of O. eichingeri and O. officinalis accessions. They were

2n=4x=48 in the tetraploid species O. alta, O. grandiglumis, O. longiglumis, O. minuta, O. punctata, and O. ridleyi. Unexpected chromosome numbers were observed in O. officinalis and O. eichingeri. In a total of 138 O. officinalis accessions, 136 were found to be diploid (2n=24), but two accessions from India were tetraploid (2n=48). Our examination also showed that four accessions (out of 18) originally identified as O. eichingeri, from Uganda and Sri Lanka, had 48 chromosomes in the root-tip cells. Considering that both O. officinalis and O. eichingeri should be purely diploid species, the correct iden-

tification of the 4x forms must be confirmed. On the other hand, this observation also indicated the possible existence of two different cytological types of O. officinalis and O. eichingeri.

In addition, a low frequency of aneuploid cells with chromosome numbers varying between 20 and 26 were found in a few accessions of O. australiensis, O. barthii, O. brachyantha, O. glumaepatula, O. granulata, O. meridionalis, O. nivara, and diploid O. officinalis. A low number of tetraploid cells with 48 chromosomes was also observed in two O. nivara accessions and six O. officinalis accessions.

Analysis of variance for combining ability. Tamil Nadu, India. 1993 DS.

Source df Mean squares F

GCA 5 0.71** 61.89 SCA 15 0.08** 7.38 Reciprocal 15 0.24** 20.70 Error 70 0.01 0.001

s 2 g 0.06 s 2 s 0.07 s 2 A 0.12 s 2 D 0.07

Predictability ratio

g = genetic component due to GCA s = genetic component due to SCA A = additive variance D = dominance variance

6 IRRN 1997

Genetics

2 s 2 g = 0.63 2 s 2 g + s 2 s

s 2

s 2

s 2

s 2 (2 s 2 g)

( s 2 s)

Calotoc and Ketan Nangka(KN)/ IR36 / / Kamairazu and tested the Est9 isozyme marker (chromosome 7). Iso- zyme analyses were conducted according to methods reported by Ishi- kawa et al (1989) and Glaszmann et al (1989). The morphological fertility of pollen was determined by staining pollen grains in 1% I2 KI solution. Round, stained pollen grains were determined to be morphologically fertile, while the small, undyed pollen grains were sterile.

razu, the morphological fertility of pollen was clearly differentiated by marker genotypes Est9-12 and Est9-11, which were derived from IR36 / Kamai- razu and KN / Kamairazu, respectively (see table). This result suggests the existence of a locus for determining pollen fertility in the morphological sense. The locus may be located near

In the F 2 lines of KN / IR36 / / Kamai-

Distribution of morphological fertility of pollen classified by marker genotypes in KN/IR36//Kamairazu and Akihikari//lR36/Calotoc.

Genotype a Plants with morphological fertility (%)

Total Mean Probability (%)

KN/IR36//Karnarazu 40 50 60 70 80 90 100

Est9-12 0 2 6 2 0 1 2 13 62.2 Est9-11 0 1 0 2 1 5 9 18 85.1 <0.01

Akihikari//IR36/Calotoc Est9-12 1 1 1 2 1 4 1 11 71.5 Est9-11 2 1 2 5 10 83.4 0.05-0.10

the Est9 with an approximate recom- Est9 on chromosome 7 has been bination value of 0.19 ± 0.13. In Akihi- reported. kari / / IR36 / Calotoc, the same result The locus for pollen fertility indi- was obtained (see table), and an appro- cated here by the isozyme marker Est9 ximate recombination value between may be identical to ga11, where sterile the locus and Est9 was estimated to be pollens were produced on hetero- 0.19 ± 0.17. zygotes at the locus near ga11 on chro-

A gamete abortion gene galla which mosome 7. A neutral allele, named

gave a recombination value of 0.23 with ga11n at the locus ga11, was identified by this study.

Correlation and heritability grain and leaf characters in indica rice in high yield- conducive environments of

of

Yunnan, China

Zeng Yawen, Chen Yong, and Liao Xinhua, Crop Germplasm Resources Station, Yunnan Academy of Agricultural Sciences, Kunming 650205, China

China has bred 15 cultivars, including Guichao 2 and Yue 517, whose yields have exceeded 15 t ha -1 with single

cropping of middle rice in the Jing- shajiang region (e.g., Yuanmou, Yong- sheng), because of favorable climatic conditions: annual mean air temperature, 17.9-21.9 °C; >10 °C cumulative temperature, 5954.1-7986.0 °C; >18 °C accumulated temperature, 4126- 6050 °C; annual sunshine, 2179.4- 2736.0 h; annual rainfall, 449.6-801.2 mm; annual evaporation of 2636-3820 mm is 3.4-6.0 times rainfall; and relative humidity, 54-64%. During the rice cropping season, about 5 mo from April to August, the >10 °C cumulative

temperature is 3822.4-4100.0 °C. For example, single cropping of middle rice at Taoyuan township in Yunnan Pro- vince requires a cumulative temperature of 1050 °C from sowing to transplanting, 2150 °C from transplanting to full heading, 880 °C from full heading to maturation, and rainfall from 411.5 to 424.4 mm. Yield components (l5-17 t ha -1 ) were 4,710,000±103.5 panicles ha -1 , 133±28.6 grains panicle -1 , and 27.6±2.3 g 1000-grain weight -1 . Fertilizer is applied heavily at early stages, lightly at middle stages, and supplementary at

Heritability (H), heritability ratio (Hr), and coefficients of genetic correlation (r) for kernel and leaf traits. a

A B C D E F G H I J K L

A 63.0 84.9 84.78 66.88 58.21 86.27 78.10 24.12 B 0.527** 79.2 47.39 C 0.902** D

66.45

E 0.763** 0.033 0.630** 0.169 98.5 99.70 98.14 98.77 F -0.311 0.394 -0.206 G 0.526** 0.679** 0.556** 0.796** 0.031 H 0.728** 0.145 -0.506** 0.053 -0.876** 0.479

77.60 91.87 0.134 68.9

I -0.452 0.155 0.174 45.91 83.03 75.08 51.00

J 0.373 0.127 -0.306 79.80 70.74 85.59

K 0.069 0.675** 0.286 0.541 -0.352 L

0.297 0.262 0.413** -0.046 0.399** 79.5 75.78

a *,**= significant at the 0.05 and 0.01 level of P, respectively. A=flag leaf length, B=flag leaf width, C=2 penultimate leaf length, D=2 penultimate leaf width, E=grain length, F=grain width, G=1000-grain weight, H=filled grains panicle -1 , I-spikelets panicle -1 , J=grain weight panicle -1 , K=grain weight plant -1 , L=yield ha -1 .

80.53 45.21 89.73 86.21 78.10 75.37 74.75 88.55 78.39

0.848** 58.6 46.58 0.670** 0.969** 0.880** 75.3

86.81 79.87 89.29 72.15 88.37 83.82 63.50 82.66 81.53 76.59 98.46

89.76 89.54 0.336 -0.763** 98.3

84.88 93.81 85.22 72.76 58.16 81.44 88.73

0.588** 96.2 85.77 73.59 73.19

91.99 67.54 95.23 97.23

88.07 67.76

0.084 -0.569** 0.827** 0.243 0.662** 70.1 0.061 -0.866** 0.908** 0.385 0.887** 0.792** 78.4 81.31 68.80

-0.716** 0.014 -0.604** -0.430 -0.813** 0.417** 0.016 0.918** 0.419 0.821** 0.422 87.2

Vol. 22. No. 2 7

late stages (207.0 kg N ha -1 , 65.3 kg P ha -1 , 124.5 kg K ha -1 ) combined with increased foliar spray.

We studied genetic correlation and heritability for a trait defined as a ratio of two kernel-leaf characters in eight high-yielding rice cultivars. A randomized block design with three replications in 10.0-m± plots of medium soil were laid out at Yuanmou (elevation 118.4 m) under high-yield ecology and conventional management in Yunnan during the 1994 season.

The heritability of each character, a ratio of two component traits, and their genetic correlation for the means of 12 traits, were calculated (see table). The results showed that kernel characters had higher heritability than leaf characters, especially grain length (8.5%), grain width (98.3%,), and grain per width (99.7%). Because the >10°C cumulative temperature was 3993.7 °C and rainfall was 424.4 mm during the rice cropping season in Yuanmou, climatic conditions were advantageous to full expression of kernel character inheritance in indica rice. Heritability of >90% included grain length/grain width (99.7%), grain length/filled grain panicle -1 (98.8%), 2 penultimate leaf initiation flowering (g m -2 ) width / yield ha -1 (98.5%), grain length / 1000-grain weight (98.1%), flag leaf width/ yield ha -1 (97.2%), flag leaf length/yield ha -1 (95.3%), grain length/ yield ha -1 (93.8%), grain width/100- grain weight (93.7%), flag leaf length/ grain weight panicle -1 (92.0%), and 1000-grain weight /yield ha -1 (91.9%). The ratio of kernel-leaf characters showed high heritability, especially grain length/width under the high- yield ecology of Yunnan. Yield ha -1 was positively and significantly correlated with filled grains panicle -1 (r=0.918), grain weight plant -1 (r=0.821), grain width (r=0.471), grain weight plant -1

(r=0.422), and spikelets panicle -1

(r=0.419). A high-yielding cultivar should have medium width and short flag leaf, short and round kernel, moderate 1000-grain weight, and increased kernel number and grain weight panicle -1 .

Heterosis: early prediction and relationship with reproductive phase

C. H. M. Vijayakumar, M. I. Ahmed, B. C. Viraktamath, and M. S. Ramesha, Hybrid Rice Laboratory, Directorate of Rice Research, Rajendranagar, Hyderabad 500030, Andhra Pradesh, India

We studied the relationship between reproductive phase and heterosis and looked for traits affecting heterosis. In the 1994 wet season at the Inter- national Hybrid Rice Observational Nursery (IRHON), 24 hybrids and their respective restorers (one plant each) were dissected to identify the initiation of reproductive phase marked by the formation of a hairy structure. Similar- ly in the 1995 wet season, three to five plants each from 20 hybrids and their 20 restorers were dissected. At maturity grain yield m -2 and observations on several yield components in five selected plants were recorded as well as

days to 50% flowering for each hybrid and restorer (Table 1). Reproductive phase initiation occurred early in hybrids. Restorer yield in parents was higher than maintainer yield in all hybrid combinations. We found a defi- nite, positive relation between better parent (restorer) heterosis and reproductive phase duration. (Table 1). In the H>R group, reproductive phase duration of hybrids was extended with no change in growth duration (days to 50% flowering). In group H<R, days to 50% flowering of hybrids was early compared with restorers but was unac- companied by a change in reproductive phase duration.

Table 2 compares yield and yield components of hybrids and restorers. The yield superiority of hybrids or restorers was positively related to plant height. The number of filled spikelets was always high in hybrids. Hybrids possessed higher values for most yield traits than restorers, except in group H<R of IR62829A-based hybrids. The

Table 1. Relationship between reproductive phase duration and heterosis. Andhra Pradesh, India. 1994-95.

Season Hybrids (no). Particulars Reproductive phase Days to 50% Difference Grain yield

1994 WS 15 H>R:Hybrid 79 a 107 28 a 641 a

:Restorer 86 109 23 509

9 H<R:Hybrid 82 a 106 a 24 474 a

:Restorer 88 110 22 583

1995 WS 8 H>R:Hybrid 64 a 95 31 a 624 a

:Restorer 68 94 25 491

12 H<R:Hyrbid 64 a 90 a 26 473 a

:Restorer 69 96 27 569

IR58025A- 5 H>R:Hybrid 64 a 96 32 644 a

based hybrids :Restorer 72 96 24 473 :IR58025B 70 93 23 323

8 :Hybrid 66 a 92 a 26 458 a

H<R:Restorer 71 97 26 577 :lR58025B 70 93 23 323

IR62829A- :Hybrid 63 92 29 a 591 based hybrids 3 H>R:Restorer 63 89 26 520

:IR62828B 62 87 25 435

4 :Hybrid 59 86 27 503 a

H<R:Restorer 65 93 28 552 :lR62829B 62 87 25 435

a P=0.05.

8 IRRN 1997

Table 2. Traits affecting yield heterosis. Andhra Pradesh, India. 1995 WS.

Particular Plant Tiller Panicle Panicle Panicle Filled Sterile 100-grain height number number length weight spikelets spikelets weight

H>R :Hybrid 107 9.88 9.00 a 26.38 3.89 139 36 2.76 :Restorer 105 9.00 7.75 25.28 3.47 113 19 2.63

H<R :Hybrid 99 9.75 8.28 26.02 a 3.50 134 a 31 a 2.51 :Restorer 104 9.83 8.33 24.52 3.34 114 20 2.32

IR58025A- H>R :Hybrid 111 9.40 9.00 27.13 3.88 144 39 2.88 based :Restorer 108 8.80 7.60 25.75 3.44 111 18 2.68 hybrids :IR58025B 98 10.00 9.00 26.02 3.48 132 32 1.94

H<R :Hybrid 101 8.88 7.63 26.74 a 3.79 142 a 31 2.61 a

:Restorer 105 10.13 8.50 24.11 3.42 118 21 2.27 :lR58025B 98 10.00 9.00 26.02 3.48 132 32 1.94

lR62829B- H>R :Hybrid 99 10.67 9.00 25.11 3.90 129 29 2.55 based :Restorer 99 9.33 8.00 24.15 3.53 115 22 2.55 hybrids :lR62829B 83 11.00 10.00 24.38 3.16 99 18 1.94

H<R :Hybrid 96 11.50 10.50 a 24.57 2.91 118 31 2.31 :Restorer 103 9.25 8.00 25.34 3.19 106 17 2.41 :IR62829B 83 11.00 10.00 24.38 3.16 99 18 1.94

a Significant at the 5% level.

yield superiority of those restorers comes mainly from grain weight. Higher yield of hybrids or restorers was related positively to tiller number and panicle number. The grain yield of hybrids in the H<R group (except IR62829A- based hybrids) was affected by tiller number / panicle number; for all other traits, hybrids were superior.

tion always early in hybrids. Hybrids yield better than parents when their days to 50% flowering is similar or later than their respective restorers. The study indicates that hybrids with better performance can be identified right in the testcross nursery by comparing their tiller number, plant height, and days to 50%, flowering with their respective restorers.

We found reproductive phase initia-

Callus induction and plant regeneration from anther culture of six high-yielding indica/basmati crosses

S. Dhaliwal, A. S. Sindhu, R. Sandhu-Gill, B. Singh, G. S. Sindhu, and S. S. Rosal, Biotech- nology Center, Punjab Agricultural University, Ludhiana 141004, India

Table 1. Callus induction from anthers of six rice crosses cultured on modified N6 medium. Ludhiana, India.

Cross/parentage Anthers cultured Anthers forming Callus (no.) calli (no.) induction (%)

Basmati 385/PR109 3,607 147 4.1 Pusa Basmati 1/PAU1198 4,899 522 10.7 Pusa Basmati 1/PR109 6,504 125 1.9 Basmati 370/IR64//Basmati 385 11,965 1,227 10.3 Basmati 385/IR64//Basmati 385 6,346 351 5.6 Basmati 385/PR4141//Basmati 385 8,822 564 6.4

Table 2. Plant regeneration from anther-derived calli in four rice crosses. Ludhiana, India.

Anther culture of F 1 hybrids facilitates recovery of rare gene combinations in a small population of doubled haploids (DH). Two main problems limit exploitation of anther culture from indica rices: low frequencies of callusing from cultured anthers and green plant regeneration from calli.

We attempted anther culture from six crosses of high-yielding indica and basmati varieties (Table 1). Young panicles were collected from field-grown plants at the commencement of flowering from primary tillers, when the distance between flag leaf base and the auricle of the penultimate leaf was 4-7 cm. After cold pretreatment (4 °C) for 7- 10 d, anthers with microspores at the early uninucleate stage were cultured

Cross/parentage Calli transferred Calli showing Calli regenerating Green plants to regeneratton shoot differentiation green plants transferred medium (no.) (no.) (%) to soil (no.)

Basmati 385/PR109 Pusa Basmati 1/PAU1198 103 44 (42.7) 47.36 14 Pusa Basmati 1/PR109 75 22 (27.3) 25.00 3 Basmati 370/IR64//Basmati 385 220 156 (70.1) 31.03 41

a Figures in parentheses are percentage values.

on media based on N6 media Cultured anthers from all crosses ex-

110 52 (47.3) 50.00 25

composition: 2.5 mg 2,4-D L -1 + 0.5 mg kinetin L -1

+ 3% sucrose. 2.5 mg 2,4-D L -1 + 0.5 mg lunetin L -1

+ 5% sucrose. 2.5 mg 2,4-D L -1 + 0.5 mg kinetin L -1

+ 3% maltose. 2.5 mg 2,4-D L -1 + 0.5 mg kinetin L -1

+ 5% maltose.

hibited callusing with varying frequency (1.9-10.7%). Highest callusing (10.7%) was observed in the cross Pusa Basmati 1 /PAU1198 on medium supplemented with 2.5 mg, 2,4-D L -1 + 0.5 mg lunetin L -1 + 3% maltose. N6 medium was found superior to Murashige and Skoog's, Blayde's, SK-8, and R-2 media for anther culture (Chu 1982, Lenka and Reddy 1994). Ammonium

Breeding methods

Vol. 22, No. 2 9

level was a critical factor: indica varieties gave better results with ammonium concentration of 3.0 mM (Chen et a1 1982). One to several globular struc- tures resembling pollen embryoids were observed in the responding anthers. Anther-derived calli regenerated either into green or albino shoots, suggesting that physiology of donor plants, stage of anther development, pre- and postcultural conditions of anthers may be responsible for regeneration of green plants. Frequencies of calli-producing green plants varied in different crosses (Table 2). Chaleff and Stolarz (1981) and Hu (1985) also reported varied frequencies of callusing and green plant regeneration in rice. Callus induction, shoot regeneration, and number of green vs albino plants appear to be under independent genetic control. Anther-derived, field- grown plants exhibited morphological trait variations. Concerted efforts are needed to increase the number of responding pollen and pollen embryos through anther/microspore culture. Use of nurse culture, maltose, and proline may increase anther culture efficiency.

Cited references Chaleff RS, Stolarz A. 1981. Factors influen-

cing the frequency of callus among cultured rice Oryza sativa anthers. Physiol. Plant. 51:201-209.

Chen LZ, Lai BZ, Liao QH, Cai xS. 1982. Medium evaluated for rice anther culture. J. Agric. Res. Chin. 31:283-290.

Chu CC. 1982. Anther culture of rice and its significance in distant hybridization. In: Rice tissue culture planning conference. Manila (Philippines): International Rice Research Institute. p 47-53.

Hu H. 1985. Use of haploids for crop improvement in China. Genet. Manipulation Crops Newsl.C1:11-23.

Lenka N, Reddy GM. 1994. Role of media and plant growth regulators on callusing and plant regeneration from anthers of indica rice. Proc. Indian Natl Acad. Sci.60:87-92.

Long days slow down panicle development of late rice strains

Shunong Bai, Chaoxing He, Minxiong Pang, Kehui Tan, Institute of Botany, Chinese Academy of Sciences, Beijing, China

This experiment probed the mechanism of photoperiod sensitivity in male sterile lines. Materials included wild type Nongken 58, conditional male sterile line Nongken 58s, Nongken 58sr (a mutant of Nongken 58s that is male fertile under long-day conditions), and a transferred conditional male sterile

line W6154s, an indica line which was obtained by a series of complicated crosses originally with Nongken 58s and Zhengshan 97. Seedlings were transplanted 25 d after sowing, and three photoperiodic regimes were im- posed: ND, the natural daylength from May to October (13-15h); LD, 16 h day/ 8 h night; and SD, 10 h day/14 h night. Photoperiodic treatments were applied from transplanting (see figure). The parameters used to define the type of photoperiodic responses were days from sowing to heading of main tillers, leaf numbers, main panicle development stage, ratio of spikelet number to

Days from sowing to heading at different photoperiodic treatments. Heading dates in each treatment were the average of three plants. Series number of the treatments follows: 1) LD; 2) SD; 3) 5 d LD + SD until heading; 4) 10 d LD + SD until heading; 5) 15 d LD + SD until heading; 6) 20 d LD + SD until heading; 7) 25 d LD + SD until heading; 8) 30 d LD + SD until heading; 9) 35 d LD + SD until heading; 10) 40 d LD + SD until heading; 11) 5 d + LD until heading; 12) 10 d SD + LD until heading; 13) 15 d SD + LD until heading; 14) 20 d SD + LD until heading; 15) 25 d SD + LD until heading; 16) 30 d SD + LD until heading; 17) 35 d SD + LD until heading; 18) 40 d SD + LD until heading; 19) ND. Only treatments 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 19 were shown in C and D.

10 IRRN 1997

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Effects of long day on panicle characteristics. a Beijing, China.

Spikelet number/panicle length Seed-setting rate (%) Line

SD LD SD LD

Nongken 58 2.83 2.23 84.1 ± 2.7 55.0 ± 11.0 Nongken 58s 3.92 3.21 77.1 ± 3.1 0 Nongken 58sr 4.55 2.94 84.9 ± 4.9 51.2 ± 5.0

a Plants treated with 7 d SD to induce panicle initiation then exposed to either SD or LD. Data collected from main tillers: average of more than three plants.

panicle length (RSL), and seed-setting ments 11-18). We found no obvious LD- rate (SSR). The experiment was re- delaying effect in the indica line peated three times. W6154s (see figure, d, treatments 12,

The data from treatments 1-10 con- 14, 16, and 18). Furthermore, when firmed that the LD did postpone the scored by Ding's panicle development transition from vegetative to repro- index, the slower panicle development ductive growth of the late japonica lines under LD conditions was at least one of tested. What was interesting to us was the major reasons, if not the only that the LD applied after panicles were reason, for the delay of heading under initiated (a minimum of 5 d SD treat- treatments 11-18 (data not shown). ment) was able to significantly delay Not only did speed of panicle deve- their development and resulted in lopment as a whole slow down, but delayed heading (see figure, a-c, treat- also organogenesis events were affec-

ted. As shown in the table, the LD conditions decreased both RSL and SSR. The lower RSL and SSR under LD might have resulted from the unfavorable effect of LD on both spikelet primordia initiation and male organogenesis.

Our data suggested that LD affects not only the male fertility in Nongken 58s but also other aspects of panicle development. They provide a new basis for understanding of the mechanism of the photoperiod-sensitive male sterility in Nongken 58s—i.e., impair- ment results in a failure of male organogenesis to respond properly to normal LD leaf signals, a failure that affects nonspecifically various aspects of panicle development. Further research on the mechanism of conditional male sterility, therefore, should focus on the response of male organogenesis to environmental signals.

Rice varieties of Kerala as Table 1. Maintainers and restorers for WA CMS lines. Kerala, India. 1994-95. a

restorers and maintainers for Genotype Kernel CMS lines Genotype Kernel CMS lines

wild abortive cytoplasmic male sterile lines

V20 A lR58025 A lR62829 A V20 A lR58025 A lR62829 A color color

PTB7 Red PF S S MO 8 Red S S S

S. L. Kumari, G. Valarmathi, T. Joseph, M. T. PTB10 Red S MO 9 Red S S S PTB32 Red PF PF PF MO 10 Red PF PF

Kanakamany, and N. K. Nayar, Regional PTB35 Red S S S MO 11 Red PF PF PF Agricultural Research Station (RARS), Mele PTB36 White S S S PMK2 White F F F

Pattambi, Palakkad, Kerala 679306, India PTB37 White S S S ADT36 White PF PF PF PTB38 White S S S ADT37 White F F F

Rice hybrids developed and released by research stations and private com- panies in India have limited adoption in Kerala because consumers there prefer bold, red kernel rice varieties. Hy- brid rice programs were initiated recently to boost production in the state, where rice is the staple food for more than 90% of the population. As a first step, we identified restorers and maintainers for the exotic cytoplasmic male sterile (CMS) lines collected from other rice centers.

PTB39 PTB40 PTB41 PTB42 PTB43 PTB45 PTB46 PTB47 PTB49 PTB50 PTB51 PTB52 MO 4 MO 6 MO 7

Red Red Red White White Red White White Red Red Red Red Red Red Red

S S

PF S

PF PF F S

PF S S S

PF S

S S S S PF PF S S F F PF PF PF PF F F S S PF S

PF S

S S S S PF PF S S

a S = sterile, F = fertile, PF = partially sterile.

ADT39 ADT42 ASD16 TPS1 C043 JJ92 Bas370 IR20 IR36 IR42 IR50 IR64 MDU4 Madhurt

White White White White White White White White White White White White White White

PF F PF PF PF - PF PF S S S S S S PF PF PF

PF F F

PF PF - F F S

Three exotic CMS lines of wild abor- oped outside the state, during the 1994 tive (WA) origin—V20 A, IR58025 A, wet season to produce 107 F1 hybrids. and IR62829 A—were crossed with 43 The hybrids and their parents were male parents from the source germ- transplanted in the main field during plasm, including 26 locally released the following dry season in rows of 10 varieties and 17 elite varieties devel- plants spaced at 15 × 20cm. Five pani-

cles from each plant were used to study fertility behavior.

A few florets each from the upper, middle, and lower part of the panicles were collected before anthesis, and pollen fertility was identified with 2%,

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Vol. 22, No. 2 11

Breeding of Z-Biao S line, the indica photothermosensitive genic male sterile line with recessive purple leaf maker

T. Xiehe, L. Zhangqian, X. Qianyi, C. Zuguo, C. Yunhua, and Z. Gaofeng, Qiannan Institute of Agricultural Sciences, Guiding 551300, Guizhou Province, People's Republic of China

We developed two photothermosensitive genic male sterile lines (PTGMS) with recessive purple leaf marker, Zi- Biao S-1 and Zi-Biao S-2, to eliminate seed contamination that may result from incomplete male sterility of

PTGMS lines in a two-line, hybrid rice seed production system.

12 IRRN 1997

Machhapuchhre 3 (MP3), the first rice variety developed through a participatory plant breeding approach released for mid to high altitudes of Nepal

K. D. Joshi, Local Initiatives for Biodiversity, Research and Development, P. O. Box 324, Pokhara, Nepal; B. R. Sthapit, Nepal Agriculture Research Council, P. O. Box 1135, Kathmandu, Nepal; R. B. Gurung, Ghandruk, Nepal; M. B. Gurung, Chhomromg, Nepal; and J. R. Witcombe, Centre for Arid Zone Studies, University of Wales, UK

Adoption rates for exotic rice varieties in the eastern and western hills of Nepal are reported to be 10-11%. Seven F 5 bulks representing three crosses— Fuji 102/CD, K332/NR10157-2B-2, and Stejaree 45/CD—were given to expert farmers identified through a village workshop. They were asked to grow and manage the new entries along with their local variety in the same way. The participatory plant breeding (PPB) system included a farm walk to different trial sites, preference ranking, measurement of farmers' managed yield data, postharvest evaluations by women farmers, and monitoring of varietal spread. Farmer-selected lines were also included in national yield trials to satisfy variety release require-

IKI stain. Three panicles each from the

Comparison of the means of top five conven- tionally bred varieties (CBVs) with that of Machhapuchhre 3.

ments. In contrast to conventional breeding practices, most farmers grew the new entries in medium fertility conditions. A few farmers chose plots they regarded as problematic. The overall strategy emphasized risk aversion and expanding successful lines to better fields. Decisions on retaining or rejecting any rice entry was largely taken after women farmers thoroughly evaluated postharvest traits, such as white grain color along with aroma, softness of cooked rice, and ability to expand and remain dry after cooking. Focused group discussion with the farmers revealed that grain yield alone did not influence farmers' decision of adopting and spreading MP3 although the variety yielded well

even in the formal varietal trials (see figure). Machhapuchhre 3 has been officially released for altitudes between 1400 and 2000 m of western Nepal, on 14 Jul l996, or less than 8 yr from the initial crossing in autumn 1988. This is the first recorded example of a successful variety developed by decentralized selection of segregating material through PPB drawing active partici- pation of expert farmers. Experience from this experiment suggests that the PPB approach is a cost-effective and suitable method for developing farmers' need-based crop varieties.

same plant were bagged before flowering to facilitate selfing. Spikelet fertility was calculated as percentage of filled grains. Hybrids showing >80% pollen and spikelet fertility were classified as fertile, those with 100% pollen and spikelet sterility were considered sterile, and the rest were classified as partially fertile. Accordingly, the male

parents were classified as restorers, maintainers, and partial restorers (Tables 1 and 2). Among the 43 varieties tested, 18 were effective maintainers, 7 effective restorers, and 16 partial restorers. The response of two varieties depended on the female parent used (maintainer/ restorer for one CMS line and partial restorer for the other), indicating the influence of the genetic background of

the female parent on the nuclear gene expression of the male parent. The frequency of main-tainers and partial restorers was very high among the red- kernel rice varieties, but practically nil among complete restorers. Hybrids with the red-kernel Kerala rice varieties when used as male parents were either sterile or partially fertile, but none was completely fertile. The sterile hybrids are being back-crossed with some of the identified maintainers (PTB39, PTB52, MO 4, MO 8, etc.) to develop locally adaptable CMS lines with red kernels for future use in hybrid rice development. The fertile hybrids are being assessed for their heterosis and adap- tability under different conditions.

Table 2. Frequency of restorers, partial restorers, and maintainers for V20 A in red- and white-kernel rice varieties. Kerala, India. 1994-95.

Varietal group Lines (no.) Restorers Partial restorers Maintainers

Red kernel 17 0 (0) a

White kernel 21 6 (28.6) 8 (38.0) 7 (33.4)

a Figures in parentheses indicate percentages.

7 (41.2) 10 (58.8)

We are developing a system for Plant regeneration from wild species of Oryza. In recent work, dehusked seeds were surface-sterilized with 0.1% (w/ v) HgCl 2 solution for 5 min and rinsed four times in sterile distilled water. Sterilized seeds were kept for germination on MS medium devoid of growth hormones in light (1600 lux) at 25 ºC. The endosperm and radicle were excised from 7-d-old seedlings, which were then inoculated on MS medium supplemented with 6.0 mg BAP L -1 . Multiple shoots or micropropagules developed at the base of shoots were used for callus initiation. Segments

G. S. Oinam and S. L. Kothari, National Centre on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi 110012, Botany Department, University of Rajasthan, Jaipur 302204, India

High-frequency plant generation in wild species of Oryza

The Zi-Biao S lines are indica-type PTGMS lines derived from the cross between Tan-Zi, a purple-leaf indica rice variety, and 1356 S, an indica PTGMS line. These lines had slower critical sterility temperature than the parent lines. Under 14-h daylength and under controlled conditions, pollen sterility was more than 99.9% and seed

Table 2. Main agronomic and outcrossing characters of Zi Biao S lines. Guizhou, China.

Plant Panicles Spikelets Grain Days to Rice Spike- Exserted Response Angle of Line height plant -1 panicle -1 weight heading quality lets stigma to GA 3 glume

(cm) (no.) (no.) (g) (%) (%) opening

Zi Biao S-1 59.7 7.5 113.6 23.0 85 Good 29.8 69.1 Sensitive 45º Zi Biao S-2 55.8 7.0 129.0 23.0 94 Good 36.3 63.2 Sensitive 41º

Table 1. Pollen sterility of Zi-Biao S lines under artificial climate chamber.

PTGMS Stage of Daily mean Mean pollen panicle temperature sterility

development a (°C) (%)

Zi-Biao S-1 III 24.07 99.99 IV 24.07 99.99 V 24.03 99.99 VI 23.01 100.00

Zi-Biao S-2 III 24.00 99.99 IV 23.01 99.99 V 23.91 99.99 VI 23.97 99.99

treatment.

a Treatment period was 4 d; sample size was 10 plants in each

set under bagging was zero (Table 1). Under natural photoperiod and temperatures in Guidion, Guizhou (26 º35' N, elevation of 1006 m), the pollen sterility of plants which flowered from 18 Jul to 29 Aug was 100%, and the complete male sterile period was 43 d. Plants which flowered after 30 Aug reverted to fertility (pollen fertility ranged from 15 to 50%).

During the fertile period, seed setting was 21.4% in Zi-Biao S-1 and 54.1%) in Zi-Biao S-2. The average temperatures in the first, second, and last 10 d were 22.0, 25.1, and 28.4 ºC in Jul l995 and 24.5, 23.5, and 25.3 ºC in Aug 1995. The monthly average day-

length was 13.61 h in Ju1 1995 and 13.02 h in Aug 1995.

Their agronomic characters and outcrossing traits were superior (Table 2). The presence of purple leaf at the seedling stage can be used as marker for eliminating selfed-seedlings of the PTGMS line in F 1 , that result from incomplete male sterility of PTGMS line owing to consecutive lower temperatures (>4 d, <24 ºC) in two-line hybrid seed production. Other rice varieties mixed inad- vertently in multiplication of the PTGMS line can also be easily removed by using the purple leaf as a marker. Thus, these lines will be useful in maintaining the purity of hybrid crops.

(0.5-1.0 cm long) cut from their white tissue were inoculated on LS medium containing 2.5 mg 2,4-DL -1 , 3%) sucrose, and pH was adjusted to 5.8. The cultures were kept in the light. Embryo- genic calli from the primary cultures were subcultured on the same medium and then transferred to regeneration

mented with 2.0 mg BAP L -1 and 0.5 mg NAAL -1 . All media were solidified with phytagel (0.2% Sigma) and growth hormones avoided. Rooted plantlets were transferred to pots.

Callus induction was observed in all wild species. Normally, callus developed at both the nodal and internodal regions of the propagules (see figure, a). Induction frequency varied among species. An embryogenic type of calli– compact, globular, shiny, and white or pale yellow—developed in all the wild species, whereas both accessions of O. meridionalis produced fast-growing nonembryogenic calli. Plant regenera-

medium based on MS salts supple-

a. Callus development from nodal and internodal regions of the shoot bases of O. nivara. b. High- frequency plant regeneration in O. nivara. c. Rooting of regenerated plantlets derived from O. nivara. d. Field transfer of plantlets raised in vitro.

tion also varied among species (see table). Both accessions of O. meridionalis failed to regenerate into plantlets and

Vol. 22, No. 2 13

Anther culture of indica/Basmati rice heterotic F 1 and F 2 hybrids and selection of desirable double haploid lines

J. S. Rohilla, J. B. Chowdhury, N. R. Yadav, V. K. Chowdhury, and R. K. Jain, Plant Tissue Culture and Genetics Engineering Laboratory, Genetics Department, CCS Haryana Agricultural University, Hisar, India; K. R. Gupta, Rice Research Station, Kual, India

Anther culture has been useful for the introgression of desirable traits into breeding populations of rice. We have been working on the transfer of dwarf- ness, defense against brown planthopper attack, and resistance to bacterial blight, from indica rice varieties to Basmati rice. This study included 12 indica rice varieties with one or more of the above mentioned desirable traits, six Basmati rice cultivars/breeding lines, and 31 heterotic F 1 /F 2 hybrids obtained from different indica / Bas- mati crosses. Basmati rice parents included Basmati 370, Basmati 385, Pusa Basmati 1 (semidwarf), and advanced breeding lines (HBC5, HBC19, and

HBC143) derived from Taraori Basmati. Panicles were collected from nethouse plants when the distance between flag leaf and penultimate leaf was 4-5 cm. Anthers were cultured in 9 cm petri dishes containing 30 ml N6 and MO19 media supplemented with either 2.0 mg NAAL -1 , 1.0 mg kinetin L -1 , and 0.5 mg 2,4-DL -1 , or 1.0 mg kinetin L -1 and 2.0 mg 2,4-DL -1 . MO19 is a modified MS medium which contains 3,134 mg KNO 3 L -1 , 320 mg (NH 4 ) 2 SO 4 L -1 , 540 mg KH 2 PO 4 L -1 and lacks NH 4 NO 3 . The media contained 40 g sucrose L -1 . Cul- tured anthers were subjected to a cold treatment at 10°C for 10 d and incubated under dark at 24+1°C. Data were recorded on percentage of anthers forming calli after 60 d. Microcalli at 2-4 mm diam were transferred to a modified MS medium containing 0.5 mg NAA L -1 and 1.0 mg each of BAP and kinetin L -1 , kept under fluorescent light of 50 µ E m -2 s -1 . Data were recorded on calli regenerating green and /or albino shoots after 30 d. Shoots were rooted and hardened in one-half strength MS medium supplemeted with 0.25 mg NAAL -1 and 2.5 mg multieffect tri-

azole L -1 (MET, CNRRI, Hangzhou, China). All the media were semi- solidified using 0.25% (w /v) phytagel (SIGMA, USA). Regenerated plants were transferred and grown to maturity in the nethouse.

Representative data are shown in the table. An advanced indica rice breeding line IET12012 showed a high frequency of androgenic calli formation (5.5%) as well as green plant regeneration (10 plants per 1000 anthers). In general, F 2 hybrids responded better to anther culture than F 1 hybrids. The F 2 hybrids involving IET21012 as the female parent were responsive to anther culture. Basmati rice genotypes were less responsive. Anthers from the F 1 indica/Basmati hybrid populations involving HBC19 produced a greater number of embryogenic calli and green plants than those from Basmati 370. A sufficient number of green plants could be obtained from some F 1 /F 2 heterotic hybrids and transferred to the greenhouse.

The success of transplantation of regenerated green plants to soil conditions during late February to end of

their calli, when subcultured, turned into roots and further proliferation of calli occurred. In all remaining wild species, plantlets developed through embryoid germination. A high frequency of plant regeneration was observed in O. nirvana (see figure, b) and O. rufipogon (Acc. 104311), whereas low frequency of plant regeneration was observed in O. rufipogon (Acc. 104308) and O. longistaminata. Embryogenic calli derived from O. eichingeri cultured on the same regeneration media failed to regenerate. Root initiation was observed after transferring shoots to growth hormone-free MS medium (see figure, c). Regenerated plants were grown successfully in the field (see figure, d) and seeds were harvested. This system of plant regeneration from embryogenic callus can provide a useful material for the improvement of rice by use of plant biotechnology.

Callus induction and plant regeneration from shoot base explant of different wild species of Oryza. a Jaipur, India.

Callus induction Plant regeneration Wild species of Oryza

Explants Explants Calli Regenerating Mean±SE planted (no.) responding (no.) planted (no.) calli (no.)

O. meridionalis 42 32 24 NR b

(Acc. 101147)

O. meridionalis 35 35 26 NR (Acc. 101148)

O. rufipogon 36 24 24 11 (Acc. 104308)

15.0 ± 1.63

O. rufipogon 37 25 25 16 50.60 ± 3.26 (Acc. 104311)

O. eichingeri 47 22 21 NR (Acc. 105152)

O. nivara 33 33 30 22 26.66 ± 6.80 (Acc. 101994)

O. longistaminata 45 31 30 11 (Acc. 101211)

2.60 ±0.24

a Callusing medium LS + 2.5 mg 2,4-DL -1 ; regeneration medium MS + 2.0 mg BAP L -1 + 0.5 mg NAA L -1 . ONR = no response; SE = standard error; - = no value.

14 IRRN 1997

-

-

-

March was of the order of 60-65%. Several of the anther-derived plants had greater number of productive tillers and greater panicle length. On an average, 70% of the plants transferred showed spikelet fertility and set seeds except in case of PR106/Basmati 370 where none of the anther-derived plants produced seeds.

One of the 51 anther-derived plants (designated as AC36) from F 1 DM25/ HBC19 hybrid showed exceptionally desirable agronomic characteristics. AC36 had an average of 12.6 productive tillers, a panicle length of 26.2 cm, and 62 filled grains per panicle. This line maintained its Basmati aroma and had a length-breadth ratio of 5.3:1.0 compared with 4.9:l in HBC19. AC36 had a 1,000 seed weight of 26.4 g compared with 21.1 in HBC19 and 17.7 in DM25. In this generation, however, none of the plants showed the dwarf characteristic of the DM25 parent.

Anther culture response of indica/basmati heterotic F 1 and F 2 hybrids.

Anthers Anthers Calli-regenerating shoots (no.) Cultivar/hybrid cultured forming

(no.) (no.) Albino Green Albino/green

Cultivar/breeding line Basmati 370 a 4200 119 (2.8) b 30 6 5.0 HBC5 a 4000 130 (3.0) 31 1 31.0 HBC19 a 3700 90 (2.4) 8 0 0.0 Pusa Basmati 1 a 4700 99 (2.1) 24 1 24.00 HKR239 4700 122 (2.6) 18 3 6.0 HKR86-104 DM25 PR106 IET12012

2200 46 (2.1) 0 0 0.0 1900 65 (3.4) 13 1 13.0 2300 51 (2.2) 0 0 0.0 2400 131 (5.5) 56 25 2.3

F1 hybrid HKR86-104/Basmati 370 a 3900 101 (2.6) HKR239/Basmati 370 a 1600 39 (2.4) DM25/HBC19 a 1600 71 (4.4)

F2 hybrid HKR86-104/Basmati 307 a 1600 81 (5.1) PR106/Basmati 307 a 1600 57 (3.6) IET2012/HBC5 a 3000 171 (5.7) IET12791/HBC5 a 1600 67 (4.2) DM25/HBC19 a 2600 113 (4.4) HKR86-104/HBC19 a 1600 69 (4.3) lET12791/HB19 a 1600 62 (3.9) Pusa Basmati 1 a /HBC19 a 2400 96 (4.0)

a Basmati rice cultivar. Values in parentheses are percentages.

55 17 54

41 37 65 53 39 26 25 22

2 1

11

7 10 40

9 6 6 8

14

27.5 17.0 4.9

5.9 3.7 1.6 5.9 6.5 4.3 3.1 1.6

Evaluation of rice hybrids in varying environments

C. Lavanya, R. Vijaykumar, and B. Sitadevi, Agricultural Research Station (ARS), Maruteru, West Godavari District, Andhra Pradesh 534122, India

Rice varieties cultivated in coastal areas of India are highly season-specific. Most of them are suitable either for wet (WS) or dry seasons (DS), but a few are suitable for both seasons. Nitrogen fertilization in WS is limited by the problem of lodging caused by frequent rains or storms. Commercial exploitation of heterosis depends on identification of hybrids adapted to variable weather and N levels. Thirty rice hybrids were evaluated in five environments at two N levels in DS, 60 and 120 N (E1, E2) and three in WS, 30, 60, and 120 N (E3, E4, and E5) (see table). They were derived from five CMS lines (IR46830A, IR54752A, IR54754A, IR58025A, and IR62829A) and six restorer lines (WGL3962,

Standard heterosis for grain yield of top 10 heterotic rice hybrids in five environments. a

Hybrid

lR54752 A/Pratibha lR54754 A/Swarna lR58025 A/Swarna lR58025 A/Vajram lR62829 A/Vajram lR54754 A/WGL 3962 lR54754 A/Vajrarn lR58025 A/WGL 3962 lR62829 A/WGL 3962 lR62829 A/WGL 3962

Range of standard heterosis in 30 F 1 s

Dry season

E1 E2

79.6** 74.9** 30.8** 46.8** 67.5** 129.3** 39.9** 77.1** 58.6** 75.5** 28.3** 8.7 45.3** 50.2**

102.2** 32.8** 81.6** 57.9** 76.7** -27.2**

-72.2 to 102.2 -78.6 to 129.3

E3

37.5** 58.5** 42.9** 74.3** 50.0** 21.1** 48.2** 57.9** 52.1** 73.4**

-38.5 to 74.3

Wet season

E4

81.7** 45.9**

112.1** 51.1** 58.3** 19.2** 44.8** 46.8** 32.2** 69.8**

-47.2 to 112.1

E5

46.2** 28.7** 57.8** 49.4** 51.9** 34.5** 15.3 15.9

6.6 42.4**

-65.5 to 57.8

a E1 = 60 kg N ha -1 , DS; E2 = 120 kg N ha -1 , DS; E3 = 30 kg N ha -1 , WS; E4 = 60 kg N ha -1 , WS; E5 = 120 kg N ha -1 , WS.

Swarna, Vajram, Pratibha, IR36, and IR64). The trial was carried out under an irrigated system at the ARS.

nerally higher in DS (806 g m -2 ) than in WS (725 g m -2 ). Standard heterosis for yield ranged from -72.2 to 129.3% over IR64 in DS and from -65.5 to 112.1% over Swarna in WS (see table). The

The mean yields of hybrids were ge-

female parent exhibited a wider range in yield, and standard heterosis ranged from -62.3 to 129.3%. Most of the hybrids performed better in one or the other season whereas some performed better in both seasons.

Five hybrids—IR54752A/Pratibha, IR54754A/Swarna, IR58025A/Swarna, IR58025/Vajram, and IR62829A/

hybrids developed using IR58025A as Vajram—gave superior performance in

Vol. 22, No. 2 15

all five environments. Five other hybrids—IR54754A/WGL3962, IR54754A /Vajram, IR58025A/ WGL3962, IR62829A/ WGL3962, and IR62829A/ Swarna—were found superior in four of the five environments studied. Their performance is mainly attributable to heterosis for the number of productive tillers per plant and the number of filled grains per panicle. Only one hybrid, IR62829A/Vajram, which ranked third in grain yield, was stable over the environments with predictable performance (b i = 1.57). Based on linear regression coefficients,

Combining ability of rice cultivars with IRRI-bred cytoplasmic male sterile lines

C. Lavanya, R. Vijaykumar, and N. Sreera- mareddy, Agricultural Research Station, Maru- teru, West Godavari District, Andhra Pradesh 534122, India

We studied the general combining ability (GCA) of 11 parents (five cytoplasmic male sterile (CMS) lines and six restorer lines) and the specific combining ability (SCA) of 30 crosses in a 5 (line) / 6 (tester) mating design. All the 41 treatments (30 F 1 s, 5 lines, and 6 testers) were evaluated in a completely randomized block design with three replications during the 1991-92 dry season (DS) under irrigation. Thirty plants for each entry were grown in three 1.5-m row plots with a spacing of 15 × 15 cm. Five competitive plants were randomly selected from each plot for analysis.

best general combiner for grain yield, the CMS line IR46830A was the best general combiner for number of productive tillers per plant, and IR54752A exhibited good GCA for panicle length (Table 1). Three CMS lines (IR58025A, IR62829A, and IR54752A) and three restorer lines (Vajram, IR36, and Swarna) were good combiners for filled grain number per panicle. The lines

The restorer line WGL 3962 was the

however, the IR58025A/Swarna hybrid with highest yield (1125 g m -2 ) and high heterosis for yield (85.8) was found to be most suitable for specific environments. The other hybrids, IR58025A/ Vajram and IR62829A/Swarna, which had above-average yield (1004 and 857 g m -2 ) and average response (b i = 0.63 and 2.06) though unpredictable for yield, may also be suitable for specific environments. All four hybrids offer greater scope for commercial exploitation of heterosis in India.

IR54752A, IR54754A, WGL3936, Swarna, Vajram, and IR36 were found to be good combiners for spikelet fertility. The line IR54754A and testers

IR64, WGL 3962, and IR36 showed good GCA effects for test weight. The line IR54752A was found to be a good combiner for a number of characters, including longer duration and plant height. Among the six restorer lines, Vajram was ranked as a good general combiner for yield, grain number per panicle, spikelet fertility, longer duration, and plant height.

Only the following hybrids showed high SCA effects for one or more characters: IR46830A/WGL 3962 for early flowering; IR54752A/Pratibha for tall- ness, spikelet fertility, and grain yield; IR46830A/Pratibha for dwarf plant height; IR46830A/Vajram for productive tillers per plant; IR62829A/Prati- bha for panicle length; IR46830A/IR36 for grain number; and IR62829A/Prati- bha for test weight. Some of these hy-

Table 1. General combining ability for grain yield and other characters of 11 parental lines.

Days to Plant Productive Panicle Grains Test Spikelet Parent 50% height tillers length panicle -1 weight fertility

flowering plant -1 fertility

CMS lines lR46830 A -7.95** -7.80** 1.60** -0.49** -24.45** -0.56* -9.55** lR54725 A 4.86** 10.41** -1.05** 1.03** 8.42** 0.36* 10.43** IR54754 A 1.69** -0.28 -1.70** -0.50** -7.81** 2.57** 3.08* IR58025 A 4.02** 3.58** 0.69* 0.65** 13.18** -0.43* -4.45**

-2.98** -5.92** 0.46* -0.69** 10.67** -1.95** 0.50 0.81 0.43 0.18 2.75 0.29 1.26 S.E. GCA (L) 0.27

Restorers

Swarna 1.23** -0.01 0.50* -0.51** 7.86** -1.75** 9.84** Vajram 1.03** 6.72** 1.10 -0.10 35.56** -1.89** 8.14** Pratibha 3.97** 1.77* 0.04 0.77* -26.16** -2.05** -21.7** IR36 1.23** -3.60** -1.00** -0.50** 13.91** 1.38** 7.90** IR64 -2.97** -2.36** -0.10 0.07 -32.32** 2.38** -10.01** S.E. GCA (T) 0.29 0.89 0.47 0.20 3.00 0.33 1.38

WGL 3962 -2.03** -2.52** 0.46 0.27* 1.16 1.93** 5.85**

Grain yield

-126.1** 83.9**

-81.8**

87.9** 36.0

9.9

160.9**

121.6** 51.8**

-191.8** -8.2

10.8 -134.3**

Table 2. SCA effects for grain yield and yield components of elite hybrids (showing >30% standard heterosis).

Hybrids Standard Days to Plant Productive Panicle Grains Test Spikelet Grain heterosis 50% height tillers length panicle -1 weight fertility yield

flowering plant -1

lR58025 A/WGL 3962 89.5 -5.02 0.02 -0.31 0.53 17.55** -0.72 1.59 209.0** lR62829 A/WGL 3962 70.0 2.64 -0.35 -1.16 -0.80 -15.30** -0.11 -3.86 34.4 lR54752 A/Pratibha lR46830 A/Vajram IR62829 A/Swarna lR58025 A/Swarna lR46830 A/IR36 lR54752 A/IR36 lR62829 A/Vajram lR54752 A/WGL 3962

68.1 -2.19 6.77** 67.5 -2.14 3.34 65.5 -0.62 -3.99* 56.9 1.71 2.08

58.6 -3.32 -5.53* 48.6 -1.76 -3.65 41.8 3.81 0.05

51.3 3.12 2.56

-0.69 0.08 3.00** -0.42 1.27 -0.55

-0.35 0.51 -0.44 0.78 -0.52 0.02 -2.00** 3.67 2.69** -0.32

24.24** 20.52**

-12.10

34.33** -6.10 3.67

-15.92**

-5.48

0.48 -0.01 -0.03 2.02 0.71

0.22 -1.11

0.88

20.90** 13.50** -8.60** 0.83

-5.85 -5.86

17.47**

-11.13**

379.2** 271.9** 114.6** -88.5** 298.0**

-62.8** -140.8**

71.7**

16 IRRN 1997

IR62829 A

brids are shown in Table 2, which also reports SCA effects of elite hybrids showing 30% standard heterosis.

The parental lines IR62829A and WGL 3962 had the highest GCA effects in their respective female and male groups for grain yield. Parents with high GCA values exhibited average SCA effects for longer duration in their

cross. Among the 10 crosses with positive SCA effects for grain yield, seven involved one good combiner for grain yield, and the others good, average, or poor, indicating interaction between positive and negative alleles. The cross combination showing high SCA effect for grain yield also showed high SCA effects for number of filled grains.

Callus induction from indica rice coleoptiles

Y. Coll, A. Gonzalez, J. Alfonso, R. Armas, M. Pujol, Centre for Genetic Engineering and Biotechnology, P.O. Box 83, C.P. 60200, Sancti- Spiritus, Cuba

Rice coleoptiles have been used in tissue culture and genetic transforma- tion, but reports on callus induction and subsequent plant regeneration from such explants in indica type varieties are scarce. We obtained significant improvements in callus induction from coleoptiles by testing different explant and culture media conditions. Mature seeds from the Perla rice cultivar were dehulled, sterilized, and the seedlings were grown on solid MS medium in the dark at 27 °C. Coleoptiles were asep- tically extracted with a scalpel from 3-, 4-, 5-, or 7-d-old seedlings and incubated in N6 medium supplemented with 2 mg 2, 4-D L -1 (N621, unless other-

1. Diagram showing basal and apical portions of coleoptiles.

wise stated. In the first attempt for in- ducing callus from both apical and basal portions from coleoptiles (Fig. 1), apical sections did not render callus re- gardless of their age in culture. Basal portions from coleoptiles cultivated for 3, 4, or 5 d produced significantly more calli than did those from 7-d-old coleoptiles (Fig. 2a), so in all subsequent experiments only basal portions from 3-d-old rice coleoptiles were used. Figure 1 shows results of culturing coleoptile basal portions in N62 medium with NAA. Adding 0.1 mg NAAL -1 resulted in a significant increase in callus induction over N62 medium containing no NAA. Concen- trations of 0.5 or 1 mg NAAL -1 also improved induction as compared with the N62 medium. Effects increasing sucrose concentration were also tested. While 4.5% sucrose increased callus formation very significantly, 6% gave results lower than the control (Fig. 2b). Effects of using 2, 4-D at 3, 4, or 5 mgL -1

were compared with those at 2 mgL - 1 . Concentrations higher than 2 mg L -1

improved callus induction (Fig. 2b), but no significant differences were found among 3, 4, or 5 mg L -1 .

containing 2 mg 2, 4-D L -1 were compared. The N6 and NMB media gave similar results and both were very significantly better than MS and AA media (Fig. 2c). Although N6 and NMB media were similar in callus induction, the NMB medium gave bigger and more embryogenic calli than those obtained with any other of the tested media or culture conditions. It also had superior results in plant regeneration frequencies.

Finally, four different culture media

2. Efficiency of callus induction in indica rice coleoptiles after different tissue culture treatments. Columns marked with the same letter within a treatment are not significantly different (p=0.01).

Vol. 22, No. 2 17

Identification of thermosensitive genic male sterile (TGMS) lines in rice germplasm

S. S. Malik, B. C. Viraktamath, and G. S. Khush, IRRI

Seventy traditional rice germplasm lines were collected from hilly areas of Koraput, Phulbani, and Mayurbhanj districts of Orissa (eastern India) where the temperature at panicle initiation (PI) stage is below 31°C. These lines, grown at the National Bureau of Plant Genetic Resources Base Center, Cuttack, during the wet season (WS) (Jun-Sep 1991) where day/night temperature is 32-24°C at PI, showed 60-100% spikelet sterility. In the dry season (DS) (Dec-Mar 1992) they showed normal fertility (30/14°C at PI). These lines, along with Yelik Meedon (IRGC 33888), a variety from Myanmar, were tested at IRRI during 1994 WS for pollen fertility. Four lines did not germinate, but some of the other 67 did (Table 1): 17 lines were fully fertile, 11 fertile, 19 partially fertile, 14 partially sterile, 5 sterile, and only Yelik Meedon completely sterile. Two plants of Navakathi were completely sterile, whereas overall sterility varied from 92 to 100%. The PI stage occurred in late August (32/24°C, based on IRRI data). Two plants of Navakathi (STM11-1 and STM11-19)

and Yelik Meedon were ratooned in Table 1. Rice germplasm lines in different fertility

pots in a screenhouse and in a phytotron. They were retested in 1995 DS in Pollen fertility Fertility class Lines (no.) the screenhouse where day/night temperatures varied from 29-21°C on Fully fertile 17

11 Feb to 34-24°C on 25 Apr when PI Fertile 11

took place in these lines in the phyto- Partially sterile 14

classes. IRRI, 1994 DS.

Partially fertile 19

tron at 27-21°C. During 1995 DS, these three lines showed variable fertility

Sterile 5 Completely sterile 1

(Table 2).

showed complete pollen sterility (100%) at temperatures higher than 31°C and Yelik Meedon at higher than 30°C at PI (18 d before flowering) but all sh owed fertile pollen at lower temperatures in the net house and phytotron. Thus, they behaved as thermosensitive genic male sterile (TGMS) lines.

These putative TGMS lines were crossed with IR64 and IR36. The F 1 s had fertile pollen (60-80%), indicating that TGMS in these lines is under recessive

Navakathi (STM11-1 and STM11-19) gene control. An F 2 population of STM11-1 and IR64 was grown during 1995 DS at IRRI. The plants reached PI stage during the first week of April when the day/night temperatures ranged from 32 to 24°C. Among the 250 plants scored for spikelet fertility, 189 were fertile and 61 were completely sterile, giving a good fit to the ratio of 3:l ( = 0.084, P = 0.80-0.70). Thus the study confirmed that the TGMS trait of Navakathi is controlled by a single recessive gene.

Table 2. Pollen fertility (%) at different temperatures. IRRI, 1995 DS.

Designation Variety Temperature (°C) at PI stage (18 d before flowering)

27-21 29-21 30-21 31-22 32-23 33-23 34-24

STM11-1 Navakathi STM11-19 Navakathi IRGC33888 Yelik Meedon

IR36 IR64

(STM11-1/IR64)F 1 (STM11-19/IR36)F 1 (IRGC33888/IR64)F 1

80 80 70 10 0 0 80 80 75 15 0 0 0 85 80 5 0 0 0 82 80 85 82

60 78 80

Floral traits influencing outcrossing rate in rice

J. Ramalingam, N. Nadrajan, C. Vanniarajan, and P. Rangsamy, Agricultural Botany Department, Agricultural College and Research Institute (ACRI), Madurai 625104, Tamil Nadu, India

Commercial seed production highly depends on the extent of outcrossing, which depends on floral characters, anthesis, anther dehiscence, and a number of environmental factors. We evaluated the amount of natural outcrossing and its relation to floral traits.

The parental lines of 20 hybrids in-

volving the four cytoplasmic male sterile (CMS) lines V20A(L1), Zs97A(L2), IR58025 A(L3), and IR62829 A(L4) and five effective restorers IR24 (Tl), IR54742-22-19-3 (T2), IR29723-143-3-2-1 (T3), IR9761-19-1 (T4), and ARC11353 (T5) were raised in a randomized block design with two replications during 1993 kharif season (Jul-Sep). A row ratio of 4:2 was adopted. Three rows of a pollen barrier, Purple Puttu, were raised around the crossing block and between each cross combination. Ten plants for both A and R lines were maintained in each row and seeds were collected from individual crosses. Ten

plants in each of four CMS lines and five restorers in each replication were selected randomly for observations of filament length (FL), anther length (AL), anther breadth (AB), and pollen diameter (PD) in restorer lines and style length (SYL), stigma length (SGL), ovary length (OL), and ovary breadth (OB) using a standard ocular micro- meter. For observation of stigma exsertion, 100 spikelets that had already opened and closed were selected from each plant. Those in which the stigmas were seen outside were counted and expressed as percentages. Simple correlation coefficients were estimated.

81-100 61-80 31-60 11-30 1-10 0

-

- - - - - - -

- - - - - - - - - - - -

- - - - - - - -

18 IRRN 1997

V. D. Patil, Y. S. Nerkar, M. B. Misal, and S. R. Harkal, Marathwada Agricultural University, Parbhani 431402, Maharashtra, India

Parag 401 is derived from a cross between Prabhavati and Basmati 370. Anthers coming from the F 1 plants were cultivated to produce doubled haploid plants. Morphology of 70 haplodiploid progenies was studied, and based on yield-related characteristics, selected genotypes were evaluated in multilocation experiments from 1993 to 1996.

Parag 401, a semidwarf rice variety developed through anther culture

IR58025 A showed the highest mean length and breadth were found in breadth. Except for stigma exsertion, outcrossing rate, 16.67% (see table). IR54742-22-19-3. High filament length none of the varieties were linked Individual combinations with high and pollen diameter was recorded for closely with outcrossing rate. The lines outcrossings were IR58025 A/ IR29723- IR29723-143-3-2-1; V20 A showed IR58025 A, IR29723-143-3-2-1, and 143-3-2-1, IR58025 A / IR24, and V20 A / lengthy stigma; and IR58025 A had IR54742-22-19-3 can be well utilized for IR29723-143-3-2-1. Maximum anther high stigma exsertion and ovary hybrid rice improvement.

Outcrossing rate in some hybrid varieties and its relationship with floral traits. Tamil Nadu, India.

Cross a Filament Anther Anther Pollen Style Stigma Ovary Ovary SE Outcrossing length length breadth diameter length length length breadth (%) rate (mm) (mm) (mm) (mm) (mm) (mm) (mm) (mm) (%)

L1/T1 1.67 2.06 0.57 0.036 1.13 1.45 0.50 0.38 35.65 18.18 L1/T2 2.32 2.70 0.76 0.038 1.13 1.45 0.50 0.38 35.65 13.13 L1/T3 2.84 1.75 0.55 0.054 1.13 1.45 0.50 0.38 35.65 18.91 L1/T4 2.25 1.66 0.61 0.035 1.13 1.45 0.50 0.38 35.65 15.90 L1/T5 1.63 1.81 0.63 0.040 1.13 1.45 0.50 0.38 35.65 15.74

Mean 16.37

L2/T1 1.67 2.06 0.57 0.036 1.44 1.07 0.58 0.52 32.00 12.21 L2/T2 2.32 2.70 0.76 0.038 1.44 1.07 0.58 0.52 32.00 L2/T3

16.09

L2/T4 18.29

2.25 1.66 0.61 0.035 1.44 1.07 0.58 0.52 32.00 L2/T5

10.41 1.63 1.81 0.63 0.040 1.44 1.07 0.58 0.52 32.00 9.53

Mean 13.31

L3/T1 1.67 2.06 0.57 0.036 1.14 1.25 0.95 0.43 42.45 L3/T2 2.32

19.00 2.70 0.76 0.038 1.14 1.25 0.95 0.43 42.45

L3/T3 2.84 1.75 0.55 0.054 1.14 1.25 0.43 42.45 20.91 16.78

L3/T4 0.95

2.25 1.66 0.61 0.035 1.14 1.25 0.95 0.43 42.45 L3/T5 1.63 1.81 0.63 0.040 1.14 1.25 0.95 0.43 42.45 16.68

9.98

Mean 16.67

L4/T1 1.67 2.06 0.57 0.036 0.79 1.36 0.92 0.36 21.81 L4/T2 2.32 2.70 0.76 0.038 0.79 1.36 0.92 0.36

2.29

L4/T3 2.84 1.75 21.81 1.28

0.55 0.054 0.79 1.36 0.92 0.36 21.81 11.94 L4/T4 2.25 1.66 0.61 0.035 0.79 1.36 0.36 21.81 5.66 L4/T5

0.92 1.63 1.81 0.63 0.040 0.79 1.36 0.92 0.36 21.81 12.01

6.64 0.40

2.84 1.75 0.55 0.054 1.44 1.07 0.58 0.52 32.00

Mean CD r 0.18 -0.12 0.24 0.40 0.38 0.01 -0.35 0.20 0.69 b

a L1 = V20 A, L2 = Zs97 A, L3 = lR58025 A, L4 = lR62829 A, T1 = IR24, T2 = lR54742-22-19-3, T3 = lR29723-143-3-2-1, T4 = lR976-19-1, T5 = ARC11353. b Significant at 5% level.

Grain quality characteristics of ACR401 compared with selected varieties. Maharashtra, India, 1993-96 a

Character ACR401 (Parag 401) Prabhavati Sugandha Basrnati 370

Plant height (cm) 71.0 75.0 44.0 85.0 Maturity (d) Iron chlorosis reaction Grain yield a (t ha -1 ) Grain type L/B Kernel elongation after cooking Gelatinization temperature Protein content(%)

110 T 3.6

LS 4.02 1.53 I 8.30

120 T 3.2

MS 3.20 1.17 L 7.0

116 T 3.3

LS 3.93 1.33 L 8.33

a LS = long slender, MS = medium slender, T = tolerant, S = sensitive, L = low, I = intermediate. Av 3 yr.

128 S

LS 1.4

4.07 2.00 I 8.40

One of the selections, ACR401 higher kernel elongation after cooking, (anther culture rice), showed superior intermediate amylose content, and quality characters over the check varie- scented grains. The genotype ACR 401 ty Prabhavati with a similar yield (see has been officially released as Parag 401 table). ACR 401 is resistant to iron chlo- for cultivation as an irrigated rice for rosis and has slender grains, high grain Vertisols of Maharashtra State. length-grain breadth ratio (L/B),

Vol. 22, No. 2 19

rmguevarra

Line

Grain quality of some Basmati genotypes

S. Santha, L. Mahalingam, T. B. Ranganathan, and W. Wilfred Manuel, Tamil Nadu Rice Research Institute, Aduthurai 612101, India

Grain size and shape must be considered in germplasm improvement along with milling percent because they largely determine the market acceptability of milled rice. Long, slender rice grain fetches a high price on the international market. Elongation of rice grains during cooking is one of the unique features of Basmati rice. Some of the key Basmati traits— slenderness, translucency, and aroma— are simply inherited, but linear grain elongation follows a complex pattern of inheritance. In thaladi 1995 (Septem- ber-October-January-February), we evaluated 23 rice genotypes along with two checks, Taraori Basmati and Pusa Basmati, for hulling, milling, head rice recovery, breadth, length-breadth ratio (L/B), and elongation ratio for rice quality improvement. A randomized block design with three replications was used on 12-m2 plots and each genotype transplanted with 20- × 15-cm spacing.

Brown rice percent among the genotypes ranged from 70.38 to 87.16% and milled rice percent ranged from 56.86 to 80.25% (see table). The highest for brown rice (87.16%) and the highest for milled rice (80.25%) were recorded for the HKR90-414 genotype. Head rice recovery ranged from 25.01 to 53.59%. The genotype RP3138-42-11-7-1 had the highest head rice recovery of 53.59%, followed by RP3121-14-70-2 (43.61%), which are higher than the check (Taraori Basmati, 27.57%). Twelve out of 23 genotypes approached the checks in kernel length and L/B. The genotypes RP3138-42-11-7-4, RP3138-78-25- 11-4, and RP3138-56-11-9-3 showed more than double the grain elongation during cooking and was higher than Pusa Basmati.

Grain quality characteristics of some rice genotypes at TRRI, Aduthurai, Tamil Nadu, India. 1995 thaladi.

Genotype Brown Milled Head rice Milled grain Cooked Elongation rice rice recovery (%)

grain ratio (%) (%) Length Breadth L/B length

UPR1071-21-1-1 81.31 73.36 41.01 6.64 1.55 4.28 10.50 1.58 RP3238-33-15-7 84.16 76.57 32.85 7.20 1.71 4.21 11.10 1.54 RP-ST-328 75.85 68.17 34.90 6.68 1.65 4.10 11.70 1.75 HKR90-421 82.54 72.95 37.13 6.93 1.64 4.22 12.30 1.77 HKR90-404 80.43 70.74 41.31 6.81 1.76 3.86 11.10 1.62 HKR90-403 84.26 79.46 25.04 6.83 1.72 3.97 13.00 1.90 HKR90-413 84.31 79.42 25.01 7.67 1.58 4.85 12.30 1.60 HKR90-414 87.16 80.25 27.61 7.73 1.62 4.77 12.00 1.55 BK843-2 80.14 56.86 25.39 7.06 1.63 4.33 11.80 1.67 BK843-7 80.55 70.66 28.69 7.30 1.62 4.51 12.50 1.71 NDR6017 82.49 73.37 41.16 6.82 1.66 4.10 11.10 1.62 HKR91-405 75.78 68.12 39.10 6.18 1.55 4.10 12.00 1.94 HKR91-406 78.12 70.41 32.45 7.91 1.74 4.55 12.90 1.63 HKR91-408 85.16 74.76 33.94 7.29 1.64 4.45 11.90 1.63 RP3138-42-11-7-1 72.97 69.34 53.59 6.92 1.69 4.09 12.30 1.77 RP3138-42-11-7-4 77.78 68.27 26.45 6.88 1.59 4.32 15.30 2.22 RP3138-78-20-9-2 80.08 70.62 29.94 6.97 1.56 4.47 12.70 1.82 RP3138-78-25-11-4 75.65 64.71 26.44 7.13 1.62 4.40 15.50 2.17 HKR92-401 84.69 75.64 33.05 7.71 1.61 4.79 12.80 1.66 RP3121-14-70-2 84.67 75.19 43.61 7.45 1.61 4.63 11.90 1.59 RP3138-56-11-9-3 78.07 67.93 26.81 6.89 1.66 4.15 14.70 2.13 RP3138-60-9-6-6 78.28 70.01 26.04 7.16 1.64 4.37 13.20 1.84 UPR-BS-92-4 78.03 66.49 26.68 7.48 1.62 4.62 13.30 1.77 Taraori Basmati 70.38 64.83 27.57 7.52 1.67 4.50 13.90 1.83 Pusa Basmati 85.18 72.17 26.06 7.64 1.64 4.66 14.50 1.89

Mean 80.33 71.53 32.47 7.15 1.64 4.31 12.60 1.76 CV 2.72 5.24 3.52 0.80 5.78 0.64 1.64 0.18

Physicochemical properties of japonica and indica waxy rice

Y. D. Kim, National Honam Agricultural Experiment Station, Rural Development Administration (RDA), Korea; S. J. Yang, National Yeongnam Agricultural Experiment Station, RDA, Korea; Normita M. dela Cruz and G. S. Khush, IRRI

Waxy rice is important for dessert and sweet products. Five japonica and five indica varieties were tested during 1996 to compare their physicochemical properties. The varieties were Sinseon- chalbyeo, Buklukbanna, Wonsanchal- byeo, Iri309, and Hwaseonchalbyeo (japonica) and Hankangchalbyeo, Iri352, IR29, IR65, and RD6 (indica).

Alkali spreading values at 1.7 and 1.4% KOH, protein, and Mg content were not significantly different except for amylose (p<0.05), K content

(p<0.05), and Mg/K (p<0.01) between japonica and indica milled waxy rices (see table). Hardness of japonica (9.83 kg) of cooked waxy rice was higher than that of indica (6.95 kg), but the other texturometer measurements were not different. The results indicated that the hardness of cooked waxy rice is an important eating quality indicator of japonica and indica waxy rice.

The water-binding capacity was significant between japonica and indica waxy rice starches (p<0.01), 196 and 183%, respectively (see table). Gel consistency, which ranges from 78 to 88 mm, is soft and not significant between them. The transmittance and swelling power of japonica were lower and higher than those of indica waxy rice starch in the slope of the curves below 70 °C. The peak (p<0.05), breakdown (p<0.050), and setback (p<0.0l) amylograph viscosities were significantly dif-

Grain quality

20 IRRN 1997

ferent between japonica and indica ences between breakdown and setback waxy rice starches, whereas the pasting amylograph viscosities because indica temperature, final at 95°C, cooled to has higher value of peak viscosity than 50°C, and consistency were not signifi- japonica waxy rice starch. cant. The results showed the differ-

Physicochemical properties of japonica and indica waxy rice. Korea, 1996.

Waxy rice

Japonica a Indica b

Milled waxy rice

Characteristic LSD c

Chemical property Amylose (%) 2.0 2.6 * Alkali spreading value (1-7)

1.7% KOH 6.3 6.5 1.4% KOH 3.8

Protein (%) 7.5 7.6

K (ppm) 2,239 2,676 Mg/K 1.28 1.09

Hardness (kg) 9.83 6.95 * Adhesiveness -1.18 -1.20 ns Cohesiveness 0.17 0.19 Springinesss 0.96 0.93 ns

ns

Gumminess 1.47 1.24 Chewiness 1.40 1.19

ns ns

ns ns ns ns

3.8

Mg (ppm) 887 893 ** **

Texturogram

Waxy rice starch Water-binding capacity (%) 196 183 ** Gel consistency (mm) 78(S) d 88(S) Transmittance (% at 625 nm)

ns

<70 °C 23.9-32.4 28.9-42.7 ** £ 70 °C 76.3-78.4 78.2-78.8 ns

<70 °C 1.4-7.7 1.33-5.1 * £ 70 °C over 20 over 20 ns

Pasting temperature (°C) 70.2 70.6 Peak 273 281 * Final at 95 °C 99 98 Cooled 50 °C

ns 135 132

Breakdown 173 183 ns

Setback -138 -149 ** Consistency 35 34 ns

Swelling power

Amylography (RVU) ns

*

a Japonica = Sinseonchalbyeo, Buklukbanna, Wonsanchalbyeo, lri309, and Hwaseonchalbyeo. b Indlca = Hankangchalbyeo, lri352, IR29, IR65, and RD6. c *,** = significant at 0.05 and 0.01 level, respectively. ns = not significant. d Based on Cagampang et al (1973) = S:soft (61-100 mm).

A method of producing Basmati rice aroma from Bassia flowers

S. Midya and R. L. Brahmachary, 21 B Mati Jheel, Calcutta 700074.

The aroma of Basmati rice was identified as 2-acetyl-l-pyrroline (AP) by Buttery and colleagues, and Schieberle developed a simple method of its syn- thesis from proline and sugar. Our

fragrance of unboiled rice is the same as that of AP. We have also traced AP in the fresh flowers of Bassia latifolia in relatively large amounts. Because syn- thesis (by both Schieberle and us) is based on the Maillard reaction, it yields only microgram quantities of AP from grams of proline and sugar. For larger quantities, production of AP from Bassia was considered.

Paper chromatographic studies first established the Bassia fragrance as that of AP. We further confirmed this result using high-performance liquid chromatography (HPLC; C18 microbondapak column, isocratic runs with methanol: water at 50:50, pump pressure 0.5 ml min -1 ). Since we have found that AP-citrate remains stable for at least 6 mo, fresh flowers were mace- rated in excess citric acid, chromato- graphically purified, and compared with GCMS-tested standard AP, which was likewise treated with excess citric acid. Peaks for citric acid and AP- citrate were clearly visible in the standard and Bassia extracts. This observation may be the first one docu- menting the occurrence of AP in a flower. Steam distillation of Bassia flower and collection in pure citric acid thus yields AP-citrate that might be utilized after purification.

Effect of degree of polish on physical and gravimetric properties of rough rice

group slightly modified this method. We reported (IRRN 17(5):9,1992) that the sweet smell of some indigenous varieties of unboiled fragrant rice was the same as that of our synthetic product, and this product, although proline-based, was different from AP. Using gas chromatograph-mass spec- trometer (GCMS) analysis, we tested pure AP from Shieberle's laboratory and have now established that the

J. P. Pandey, Post Harvest Process and Food Engineering Department, G. B. Pant University of Agriculture and Technology (GBPUAT), Pantnagar 263145, Nainital, India

Knowledge of rice's physical and gravimetric properties, such as grain size, bulk density, and porosity are important for designing systems for handling, transport, storage, drying, and other processes. Degree of polish is a most important parameter for trade purposes because milled rice quality, amount of bran, and oil content depend on it. This study determined the pro-

Vol. 22 No. 2 21

perties of three rice varieties (Pant Regression coefficient (r) and standard error of estimate (SEE) for grain characteristics with rate of bran

Dhan 4, Pant Dhan 10, and Pant Dhan removal. Pantnagar, India.

121, collected from a university rice Pant Dhan 10 Pant Dhan 10 Pant Dhan 12 breeder, at 13 ± 1.00% dry basis grown Grain characteristic in northern India. Cleaned rough rice was shelled, and unshelled ones were Physical properties

SEE r SEE r SEE

separated; brown rice was milled in a laboratory rice whitener (model Tm-25 Width (W)

0.700 0.200 0.690 0.060 0.650 0.057 0.985 0.007 0.883 0.030 0.860 0.015

Satake) for 10-110 s at 10-s intervals to Thickness (T) 0.886 0.035 0.925 0.023 0.860 0.015 attain different degrees of bran Length-width ratio 0.630 0.107 0.054 0.046 0.109 0.032

removal. Width-thickness ratio 0.693 0.020 0.550 0.027 0.969 0.009

Length (L)

Relations between degree of polish, L X W X T 0.959 0.695 0.960 0.533 0.936 0.370

time of milling, milling yield, physical dimensions, and gravimetric properties Gravimetric properties

were calculated by regression analysis. Mass (M) 0.927 0.051 0.847 0.120 0.827 0.089 Only those models for which the r Bulk volume (VB) 0.915 0.177 0.942 0.111 0.841 0.279

value was greater than 0.80 for linear Bulk density (DB) True volume (VT) 0.810 0.149 0.841 0.141 0.936 0.049

0.959 0.229 0.960 0.136 0.936 0.365 relation were considered. The statistical True density (DT) 0.786 0.023 0.652 0.009 0.800 0.020 results are summarized in the table.

Effects of genotype x soil the most widely cultivated variety in cooked rice, were highest in rice grown interaction on rice grain quality Korea. in this same soil series. The values of

in japonica rice The contents of Mg and Mg/K were maximum viscosity and breakdown lowest in rice grown in the Yaesan soil were higher in rice grown in 4th class

Kyu-seong Lee, Young-doo Kim, and Hyun-tak Shin; National Honam Agricultural Experiment

series, the most inferior soil. The hard- soil than those in 1st and 2nd class soils ness and chewiness, among textures of (Table 2).

Station, Rural Development Administration, P.O. Box 5, IRI 510, Republic of Korea Table 1. A classified standard soil class according to physical parameters for paddy field based on Korean soil

series.

We evaluated quality (chemical compo- Slope angle Effective soil Total

nents, texture of cooked rice, and amy- Soil series

logram characters) of rice grown under Chonbuk Clay-loam Very rapid <2 >100 1 different conditions (soil texture, drain- Yongji Clay Rapid 2-7 50-100 2

Soil texture Drainage (%) depth (cm) soil class

age, slope angle, and effective soil Seongsan Siltyclay loam Moderate

depth) (Table 1), using Dongjinbyeo,

7-15 20-50 Yaesan Silt loam Slow >15 <20

~

3 4

Table 2. Effect of soil and environment on chemical components, texture, and amylogram characteristics of rice quality in Dongjin rice variety. Korea. 1995-96.

Chemical component a Texture of cooked rice a Amylogram characters a

Soil series Samples/ and location location Amylose Protein Fat Ash Mg K Mg/K Hard- Adhesive- Cohesive- Chewi- Maximum Minimum Final Break-

(no.) content (%) (%) (%) (ppm) (ppm) ness ness ness ness visco- visco- visco- down (%) sity sity sity

Chonbuk at 9 18.4a 7.39a 1.40a 1.40a 832a 2074c 1.31a 5.78b 1.69a 0.36a 1.88b 402b 321a 571a –169bc lksan

Yongii at 6 17.7a 7.38a 1.40a 1.40a 840a 2173ab 1.25ab 5.17b 1.03a 0.32a 1.36b 442ab 318a 582a –140b Changseong

Seongsan at 6 17.6a 7.77a 1.43a 1.43a 837a 2137bc 1.15bc 4.85b 1.42a 0.34a 1.29b 429ab 325a 575a –122b Naju

Yaesan at 6 18.0a 7.33a 1.40a 1.43a 761b 2226a 1.01c 9.14a 1.34a 0.36a 2.37a 484a 337a 564a – 80a Jeungup

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

r

22 IRRN 1997

The results indicate that chemical properties of rice grain, particularly Mg content, and Mg/K were higher in favorable soil types than in unfavorable ones where the plants grow more slow- ly. Some characters related to cooking quality, however, could be reversed because the starch tissue of grain produced under an inferior soil class may be caused by slow translocation and by insufficient nutrient uptake of plants.

An assessment for yield estimation in upland rainfed ecosystem of Bastar Plateau Zone, Madhya Pradesh

S. Rao, IGKV, Zonal Agricultural Research Station, Jagdalpur 494005 Bastar, Madhya Pradesh, India

The relation between grain yield and yield components can be expressed as Grain yield (g m -2 ) = No. panicles m -2 × no. spikelets panicle -1 × % fertile spikelets panicle -1 × weight of single spikelet (g) (De Datta 1981, Arraudeau and Vergara 1988). This formula does not hold well for rainfed upland rice when the paired t test is applied. Therefore I attempted various multiplication factors and finally ended up with 0.5, as described in this note. A complete block design with three replications was used during the wet seasons (WS) of 1992 and 1993, with 26 and 21 entries, respectively. They were direct-seeded (10 g m -2 in eight plots, 4 m in length, with 25-cm row spacing. The soil was low in available N and P 2 O 5 and medium in available K 2 O (220.0, 9.6, and 220.0 kg ha -1 ) at pH 5.6. A dose of 40-8.8-8.3 kg NPK ha -1 was applied. Five plants were randomly selected from each plot to record observations on a randomly selected 1-m 2 area (Tables 1 and 2). Grain yield was estimated by substituting the yield attributes in the conventional and a modified formula for all the genotypes. Paired t tests for observed grain yield

Table 1. Yield attributes and estimated grain yield of extra early and early rice genotypes under upland rainfed ecosystem. Bastar Plateau Zone, Madhya Pradesh, India. 1992 WS.

Genotype Panicles m -2 Filled Spikelet 1000- Grain Estimated grain (no.) spikelets fertility grain yield yield (g m -2 )

panicle -1 (no.) (%) weight (g) (g m -2 ) Conventional Modified

R281 PP31-1 295 53.5 R302-111 262 58.5 JR80-4-6 342 40.9 JR82-10 322 46.5 JR84-7-1-19 270 51.2 RWR78-71-9 387 RNR-1446 341 CR92-65 260 52.9

41.7 40.7

Vanprabha 217 45.1 Heera 281 46.3 Poorva 339 46.7 Kalinga 3 362 44.5 Tulasi 348 52.1 Annada 340 57.5 Jawahar 75 322 48.4 RR180-1 263 48.9 RR51-1-1-7 274 41.3 RR151-3 301 42.5 Aditya 272 40.2 Rasi 345 46.0 Tellahamsa 339 51.3

Kakudo 290 48.6 Palsul 254 80.7 Badoldhan 217 86.8 Bhilaimuch 321 79.8

Mean 302 52.4 CD (0.05) 89.3 10.9 t value Goodness of fit

B3619C-PB8 302 69.5

a ** = significant, p=0.01. b nonsignificant.

80.7 24.0 126.3 305.5 152.7

81.4 19.4 100.7 221.0 110.5

77.8 28.1 187.7 302.1 151.0

89.9 22.7 158.3 283.6 141.8

69.8 22.4 140.8 203.5 101.7

81.7 23.8 167.3 312.9 156.5 82.0 24.8 152.5 368.5 184.2

73.3 24.0 132.0 269.5 134.8

73.0 23.3 122.0 254.6 127.3

79.0 82.8 142.0 290.5 145.2

83.6 26.3 152.0 302.7 151.0 77.2 25.0 107.2 189.1 94.5

76.3 26.8 129.6 323.5 161.8

81.3 26.9 177.6 427.4 213.7 77.6 22.7 156.0 272.6 136.3 79.4 26.5 166.0 270.7 135.4 76.0 25.0 162.3 214.9 107.5 86.7 24.7 159.3 274.1 137.0 81.4 28.6 176.3 254.5 127.2 80.6 22.0 138.3 281.4 140.7 82.6 23.7 182.7 340.8 170.4 87.1 23.4 156.7 428.1 214.0 80.4 21.8 158.7 246.9 123.5 86.1 19.5 177.6 344.1 172.0 86.9 26.2 203.7 429.2 214.6 85.3 9.8 115.0 214.2 107.1 80.6 23.6 151.9 293.3 146.6

5.2 2.8 12.9 0.96 ** a ns b

Table 2. Yield attributes and estimated grain yield of extra early and early rice genotypes under upland rainfed ecosystem. Bastar Plateau Zone, Madhya Pradesh, India. 1993 WS.

Panicles m -2 Fllled Spikelet 1000- Grain Estimated grain Genotype (no.) spikelets fertility grain yield yield (g m -2 )

panicle -1 (no.) (%) weight (g) (g m -2 ) Conventional Modified

R281 PP31-1 275 63.1 83.2 24.1 140.4 JR80-4-6 289 66.4 85.8

347.9 173.9 22.7 204.6 373.6

JR82-1-10 309 68.4 80.4 27.2 253.4 186.8

JR84-7-1-19 459.6

279 RWR78-71-9

71.1 83.2 27.8 283.4 459.3 229.7 335 64.3 84.0 24.0 257.9

RR149-177 274 434.6 217.3

RR151-3 236 147.7

68.1 RR166-645

85.4 27.9 205.9 382.9 256 74.5 82.9 28.5 230.4

191.2

RR180-1 213 63.0 87.9 29.4 227.1 347.2 173.6 450.9 225.5

229.8

51.8 85.6 24.3 168.4 295.4

Kalinga 3 294 60.6 80.7 24.8 165.4 356.1 178.0 Annada 272 76.2 88.9 27.6 285.4 509.3 254.6 Poorva 260 51.0 82.1 Aditya 306 60.6

27.9 138.4 303.7 88.7 29.6 189.1 487.3

151.8 243.6

Tulasi 268 69.9 90.0 25.4 270.4 428.6 214.3 Rasi 305 67.1 87.3 24.1 250.9 430.4 215.2 Tellahamsa 283 67.0 RNR1446 298

88.2 26.1 255.4 436.9 64.9

218.4 89.1 25.2 226.6 434.5

Badoldhan 199 79.0 90.5 28.2 197.5 217.3

lR55423-15 401.1

191 200.5

83.3 TRC87-2-51

86.2 27.9 192.9 382.5 191.2 274

CR692-600 86.9 86.5 21.5 257.1

242 442.6

81.9 221.3

88.5 26.5 232.1 465.2 232.6 Mean 269 68.5 85.9 CD (0.05) 70 16.2 4.8 2.4

26.2 218.0 415.0 207.6

t value Goodness of fit -

16.2 1.45 ** a ns b

a **=significant, p=0.01. b nonsignificant.

Yield potential

Vol.22, No.2 23

- - -

- -

- -

- -

- - -

- - -

- -

- -

- -

- - -

-

were similarly calculated for both the years of study.

The test assumes that both values were at par, and results showed that goodness of fit was significant for the conventional formula and nonsignificant for the modified formula. One of the reasons for the difference might be the prevailing climatic conditions. The low fertility and typically poor yield of the upland ecosystem may be attribu-

table to the low average of sunshine hours per day in the wet season in Bastar Plateau Zone. The average sunshine hours per day during the crop growing months (Jun, Jul, Aug, and Sep) were 6.3, 3.7, 2.2, 6.7 in 1992 and 5.6, 3.9, 2.5, 5.3 in 1993. Cloudy weather prevailed during both vegetative and reproductive crop stages. Hence, use of the modified formulas seems to be accurate for assessing extra-early and

early rice genotypes grown in the upland rainfed ecosystem of Bastar Plateau Zone.

Cited references Arraudeau MA, Vergara BS. 1988. A

farmer's primer on growing upland rice. Manila, Philippines: International Rice Research Institute.

De Datta SK. 1981. Principles and practices of rice production. New York: John Wiley & Sons.

GPIR-22: a gene pool developed to improve partial resistance to blast of upland rice

B. Courtois, IRRI/Centre de cooperation inter- nationale en recherche agronomique pour le developpement, France; C. Mendoza, R. Nelson, and W. Petalcorin, IRRI; E. Roumen, Center for Genetic Engineering and Biotechnology, Rama IV Road, Rajdhevee, 10400 Bangkok, Thailand

Durability of blast resistance is a major concern in the upland ecosystem. Partial resistance may be more durable than complete resistance because it appears to be largely race-nonspecific. It cannot be assessed, however, unless one has a virulent strain effective against major genes. An isolate compatible with the highest possible number of parents may be used to overcome major genes in a population, which is then purged of the remaining major gene(s) conditioning resistance to such an isolate. Only the major genes efficient against the chosen isolate are discarded and the other major genes retained. Once such a population is built, lines with a susceptible infection type but having a reduced relative infection efficiency after inoculation with the compatible isolate can easily be selected. The effective major genes that were purged from the population can be introduced at the end of the program in order to have the best partial resistance and the best major genes. GPIR-22 is a poly-cytoplasmic gene

pool we constituted following this dry season (DS). The isolate V85-0256, strategy. which has the broadest virulence

Eight monoconidial isolates among spectrum and gives consistent results those we used most widely were tested on the parents, was chosen as reference. against 50 potential parents using Based on their isozymic diversity, 24 monocyclic inoculation tests in the 1994 upland varieties were chosen (see

Building GPIR-22 through circular hybridizations.

Pest resistance — diseases

24 IRRN 1997

Varieties chosen as parents to constitute the gene pool.

Compatible reaction Varietal Incompatible reaction with the isolate group with the isolate

Varietal group

Azucena Arias B2997C-TB-60-3-3 CT6510-24-1-2 lR53236-280 lR55419-04

IRAT 169 F10/6 Lubang red Palawan Speaker Vandana

lR55435-05

6 6 1 1 1 1 1 1 1 6 6 1

table). Twelve of them were susceptible to the chosen isolate and 12 were resistant.

The gene pool was created through three rounds of hybridization (see figure). To preserve the different cyto- plasms, the hybridization scheme was circular. In the 1994 wet season (WS), each susceptible parent was crossed with a resistant one. The resulting F1

hybrids were all expected to be resistant, since resistance attributable to a major gene is generally dominant. The

62667 Araguaia Diwani lR58662-04 IR60080-46A lR63380-08 IRAT 104 IRAT 212 IRAT 216 Ketan Menah

Med Noi P5589-1-1-3P

6 6 1 6 6 6 6 6 6 6 6 6

second round of crosses, done in 1995 DS, involved intermating between F 1 s. The resulting double hybrids were segregating for the resistance/susceptibility to the isolate. Only the double recessive plants were transplanted in the hybridization block for the third round of crosses in the 1995 WS. The gene pool was then built with equal representation of the resulting hybrids.

The development of the GPIR-22 took 2 yr. Its improvement through re- current selection has already started.

Intensity of the attack of Sitotroga cerealella (Olivier) in rice genotypes and its effect on seedling emergence

E. Ferreira, N. R. Vieira, and E. da M. de Castro, Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) / Centro Nacional de Pesquisa de Arroz e Feijião (CNPAF), Caixa Postal 179, Goiânia, Goiás 74001-970, Brazil

Angoumois grain moth (AGM), Sito- troga cerealella (Olivier), a storage grain pest, is responsible for great damage on seeds, causing weight loss, reduced nutrient content, and loss of viability. This study determined the correlation between levels of AGM storage infestation and seed performance of different rice genotypes.

The effect of AGM attack, which is related to the intensity of infestation,

14 mo. After incubation, the percentages of infested seeds and weight loss ranged, respectively, from 10.5 to 61.5% and 5.5 to 26.1 %. In addition, AGM- infested seeds were separated by genotype and subjected to the emergence evaluation in a screenhouse (Table 1).

Seeds were planted in plastic trays (50 × 42 × 8 cm), containing homo- genized soil, in a completely randomized design with three replications of 20 seeds each, in a two- factor arrange- ment with five levels of infestation and nine genotypes. Emergence performance was evaluated 15 d later by counting the emerged seedlings and expressing the results in percentage for statistical analysis.

Both factors, genotype and level of infestation, had significant effects on seedling emergence but no interaction was observed between the factors. The majority of the genotypes showed a linear type response, with a consistent negative trend in emergence response to increased infestation levels. Only two genotypes, CNA 7451 and CNA 7890, demonstrated a quadratic effect. The regression equations calculated for each genotype are presented in Table 2.

By the end of the test period, around 1.8% of the emerged seedlings had died and 7.5% showed reduced growth.

was evaluated in nine genotypes ran- Significant differences were observed domly drawn from a tota1 of 45 geno- among genotypes subjected to the same types naturally infested in a field trial. level of infestation, and cultivars

was placed in plastic boxes (16 × 12 × 6 emergence rates. cm) and incubated in the laboratory for

Approximately 400 g of each genotype Guarani and IAC47 had the highest

Table 1. Influence of grain moth Sitotroga cerealella (Olivier) level of infestation on seedling emergence of different rice genotypes. Santo Antônio de Goiás, Brazil. 1995.

Level of infestation

Genotype 00 80

Emergence (%) SE Emergence (%) SE

CNA7645 41.7 11.5 8.3 5.8 CNA7690 70.0 5.0 18.3 5.8 Guarani 78.3 5.8 26.7 5.8 CNA7451 61.7 12.6 15.0 5.0 CNA7864 76.7 7.6 15.0 5.0 CNA7890 63.3 10.4 30.3 18.6 IAC1343 63.3 7.6 11.7 7.6 CIAT20 73.3 10.4 13.7 12.0 IAC47 81.7 7.6 15.0 8.0

Table 2. Regression equations calculated for each genotype considering seedling emergence as dependent variable of intensity of AGM attack. Santo Antônio de Goiás, Brazil. 1995

Genotype Regression equation R 2 a

CNA7645 Y 1 = 45.000 - 0.458x 0.945** CNA7690 Y 2 = 64.333 - 0.625x 0.948** Guarani Y 3 = 78.000 - 0.708x 0.932**

+ 0.007x 2 CNA7451 Y 4 = 62.048 - 1.155x 0.993**

CNA7864 Y 5 = 73.333 - 0.708x 0.968** CNA7890 Y 6 = 62.790 - 1.074x 0.935*

+ 0.008x 2

CIAT20 Y 8 = 71.267 - 0.780x 0.976** IAC47 Y 9 = 81.333 - 0.817x 0.995**

a **=significant at .01 level of probability, *= significant at .05 level of probability.

IAC1343 Y 7 = 60.000 - 0.583x 0.897

Vol. 22. No. 2 25

Pest resistance—insects

lndur Samba—a superfine- grain, short-duration, gall midge-resistant rice variety

M. Ganesh, T. Pradeep, N. N. Reddy, C. H. Surender Raju, C. P. Rao, K. R. Tagore, N. S. Reddy, B. Ragaiah, P. S. S. Murthy, and T. S. Rao, Regional Sugarcane and Rice Research Station, Acharya N.G. Ranga Agricultural University, Rudrur 503188, Naizamabad, Andhra Pradesh, India

Indur Samba (RDR763) is a short- duration (120-125 d) rice variety derived from Samba Mahsuri/ Surekha. It is resistant in gall midge endemic areas (Table 1) where sowings extend until 30 Jul in the wet season, and it is suitable for cultivation in winter and summer seasons. Indur Samba is a dwarf plant (75 cm) with medium-tillering (panicle-bearing tillers, 15-16 hill -1 ) and erect leaves (see figure). It is semicompact, photoperiod- insensitive, and fertilizer-responsive. All plant parts are green. Panicle exsertion is complete. The panicle length is 18.9 cm with 213 grains panicle -1 . The test weight is 15.2 g and 12.2 g (kernel). Head rice recovery is 67%. It recorded grain yields higher by 17%, than check Hamsa, and grain yield potential is 7.0 t ha -1 (Table 2).

Indur Samba is a super fine (medium slender grain) rice variety with kernel length (L) 5.388 mm and

breadth (B) 1.854 mm (L/B of kernel 2.905 compared with 2.829 of Samba Mahsuri). Abdominal white is absent

lndur Samba (RDR-763)- A super fine rice variety with 120-125 days duration, high yield potential and suitability for gall midge endemic areas.

and cooking quality is good. Indur Samba can supplement the locally popular Samba Mahsuri, another super fine (medium slender) grain type of long duration (150 d) that is susceptible to major pests and diseases. Indur Samba has gained wide popularity among the farmers and is grown in 5000 ha in the northern Telangana Zone.

Table 1. Reaction of lndur Samba (RDR763) to gall midge in screening trials at Jagtial, Warangal, and Rudrur, Andhra Pradesh, India. 1995 wet season.

Jagtial Warangal Rudrur Variety

Silvershoots (%) Damaged plants (%) Silvershoots (%) Gall midge incidence (%)

30 DAT a 50 DAT 30 DAT 50 DAT 30 DAT 50 DAT 30 DAT 50 DAT

0 1 0 5 0.00 0.20 3.10 0.00 (0.24) b (2.90)

RDR763

TN1 (susceptible check)

Samba Mahsuri 7.30 12.70 (susceptible check) (20.00) (23.00)

a DAT = days after transplanting. b Figures in parentheses are far 1994 WS.

Table 2. Performance of lndur Samba (RDR763) and check variety in different station trials at Rudrur.

14 24 91 100 6.81 12.71

Season Grain yield (t ha -1 ) Increase

Trial a over check

Winter 1990 OVT 1990 wet season PVT 1991 wet season AVT

3.8 2.8 5.2

3.3 16.0 2.3 19.0 4.4 17.6

a OVT = observation variety trial, PVT = preliminary variety trial. AVT = advance variety trial.

Screening for tolerance for iron toxicity

J. O. Nipah, Crop Science Department, Faculty of Agriculture, University of Science and Technolo- gy, Kumasi, Ghana; M. P. Jones and B. N. Singh, West Africa Rice Development Association (WARDA), 01 B.P. 2551, Bouak 01, C te d'Ivoire, West Africa; O. S. Kantanka, Crop Science Department, Faculty of Agriculture, University of Science and Technology, Kumasi, Ghana; and K. L. Sahrawat, WARDA

This study identified the appropriate time to visually score rice germplasm in

order to select materials having the lowest yield reduction under iron toxicity. The experiment took place at Korhogo, 9° 22' N 5° 31' W, in northern C te d'Ivoire, during the wet season (May-Aug 1995) using a randomized complete block design with three replications on an irrigated Ultisol lowland that contained 343 ppm Fe in soil solution at the beginning of the season. Of 28 transplanted, Suakoko 8 and Bouak 189 were tolerant and susceptible checks, respectively, and two O. glaberrima were land races.

Each plot of 40 hills had a planted border using the check varieties. The experiment was repeated simulta- neously on a nearby control field which was free of iron toxicity. Plant parameters studied are shown in the table. The varieties were scored for leaf symptom-based tolerance for iron toxicity at 15 d intervals from 15 to 90 d after transplanting (DAT). To obtain a measure of iron toxicity symptoms across phenological stages, the cumulative toxicity score was also analyzed.

- - - - - -

RDR763 (check) Tella Hamsa (check) (%)

- -

Stress tolerance — adverse soils

26 IRRN 1997

Table 2. Yield and grain quality of Yumenohatamochi and Tsukubahatamochi in drought years. Ibaraki, Japan.

Total test years a Drought years b

Variety Yield Rate Grain Yield Rate Grain

(t ha -1 ) (%) quality c (t ha 1 ) (%) quality c

Yumenohatamochi 3.42 111 5.2 1.64 148 5.2 Tsukubahatamochi 3.09 100 5.0 1.11 100 5.9 a From 1989 to 1995. b 1992 and 1994. c 1=excellent, 10=poor.

Table 1. Characteristics of Yumenohatamochi and popular local variety Tsukubahatamochi. Ibaraki, Japan.

Character Yumenohatamochl Tsukubahatamochi

Duration (d) 124 121 Culm length 71 78 (cm)

Panicle length 19.8 20.5 (cm)

Panicle number 316 297 (no. m 2 )

Yield (t ha -1 ) 3.42 3.09 1,000-grain 21.9 20.4 wt (g)

Grain quality a 5.2 5.0 Eating quality b 1.0 4.0

a Av from 1989 to 1995. b 1 = excellent, 9 = poor,

In 1996 in Japan, upland rice was grown on 13,000 ha, or 0.7% of the total rice cultivated area, and comprised only 0.3% of the total rice produced. A new upland rice variety Yumenohata- mochi has been released into Ibaraki, Toichigi, and Gunna prefectures, which had about 60% of the total Japanese upland rice area in 1996. Yumenohata- mochi means "dreamy (excellent) glutinous upland rice" in Japanese. It is derived from the cross Norinmochi 4 / / / Norinmochi 4/JC8l/ / Norinmochi 4. The traditional Indian variety JC8l was chosen as parent because of its deep root system. Norinmochi 4 is a Japanese upland rice variety with high resistance to blast. Yumenohatamochi is a medium-maturing variety with medium culm length (Table 1). This variety inherited abundant rooting in deeper soil layers from its parent, JC8l.

N. Nemoto, M. Hirayama, K. Okamoto, M. Miya- moto, and R. Suga, Plant Biotechnology, Ibaraki Agricultural Center, Kamikunii, Mito, Ibaraki 311-42, Japan

Yumenohatamochi, a new upland rice variety in Japan

Evolution of iron toxicity symptoms in stressed and control fields and coefficients of variation at different stages of assessment. Data pooled for 28 genotypes and 3 replications.

The sativa varieties ranged between 124 and 142 d to maturity (mean of 130), and average iron toxicity across varieties increased to a maximum of 4.8 at 75 DAT, with a range of 2.0-7.0 (1 = no symptoms; 9 = dead plants). Eleven entries showed maximal symptoms at 60 DAT, 24 at 75 DAT, and 15 at 90 DAT. Those with marginal symptoms at these sampling dates included the two O. glaberrima land races, which attained their maximum score at 45 DAT. The lowest coefficient of variation of 20.08% for iron toxicity scores across genotypes was also observed at 75 DAT (see figure).

Iron toxicity caused significant reductions (P < 0.001) in agronomic parameters as compared with the control plot, but the scores were significantly

Correlation between three ways of assessing rice varieties for tolerance for iron toxicity and some agronomic parameters.

Parameter Score at Maximum Cumulative 75 DAT a score score

% height reduction 0.63** 0.61** 0.69** % yield reductton 0.60** 0.64** 0.74** % panicle reduction 0.46* 0.47* 0.54** % tiller reduction -0.003 ns -0.015 ns 0.021 ns % spikelet reductton 0.11 ns 0.13 ns 0.24 ns

a DAT = days after transplanting.

correlated with reductions in yield (r = 0.63**) and plant height ( r = 0.59**). No such relation was noted with reduction in tiller number (r = -0.003 ns).

The cumulative score may be the best parameter to assess varieties, as it showed the highest correlations with agronomic performance, especially yield (see table).

Root tips of Yumenohatamochi reached to a soil layer of 85 cm depth, which

other varieties. Therefore, Yumenohata- was about 20 cm deeper than those of

mochi showed outstanding yields in the drought years of 1992 and 1994 (Table 2). The drought resistance of this variety is the highest of other released upland rice varieties in Japan.

In general, glutinous rice is used to make rice cake. The eating quality of rice cake from upland rice has been inferior to that of lowland rice varieties. Only lowland varieties have been used to make rice cake. According to eating quality studies performed in our institute, however, rice cake made from Yumenohatamochi showed high smoothness and softness and it was similar to rice cake made from lowland rice varieties. Eating quality of Yume- nohatamochi was shown as the best among Japanese upland rice varieties.

Integrated germplasm improvement—upland

Vol. 22, No. 2 27

ASD20: a new short-duration rice variety for Tamil Nadu, India

P. Shanmugasundaram, K. Mohanasundaram, M. Rangasawamy, K. Ganesan, W. Wilfred Manuel, T. Sundaram, S. Ganapathy, P. Vivekanandan, M. Arumugam Pillai, and M. Velusamy, Rice Research Station (RRS), Ambasamudram 627401, Tamil Nadu, India

IR44595-70-2-3-3, a cross-derivative of IR64/IR25863-61-3-2//IR58, was received through the International Rice Testing Program in 1988 and subjected to further selection at RRS. It was designated as AS89044 and released as ASD20 in Jan 1997 for general cultivation in Tamil Nadu.

ASD20 is a semidwarf hybrid (89 cm) and matures in 110 d. At this station, it produced a mean yield of 6.7 and 5.6 t ha -1 in dry (June to September) and wet seasons (October to January), respectively. The performance in multilocation, adaptive, minikit, and national trials was good; it registered a mean yield of 5.7 t ha -1 in 320 trials with a 5.6, 9.6, and 9.6% increased yields over ADT36, ASD18, and IR50, respectively (see table). The biological yield of ASD20 is 18.5 t ha -1 (6.7 t ha -1 grain, 11.8 t ha -1 straw) and its potential grain yield is 9.7 t ha -1 .

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Mean yield performance of ASD20 in different trials. Tamil Nadu, India. 1988-96.

Mean grain yield (t ha -1 )

Trials (no.) ASD20 ADT36 IR50 ASD18 Annada Tulasi Trial/year

Station trial Dry season 11 6.7 6.2 5.5 5.7 - -

% increase over checks 8.1 21.2 17.9 - -

Wet season 6 5.6 4.5 4.7 4.7 - -

(1988-96)

(1990-91 to 1995-96) % increase over check 25.4 19.5 20.4 - -

Multilocation 19 4.8 - 4.5 4.4 - - trial (1991-92) % increase over check 8.2 8.9

Adaptive research 197 5.5 5.4 5.3 5.3 - - trial (1992,1993, and 1996) % increase over check 3.1 4.5 5.3

National trial 25 5.3 - - - 4.5 4.6

% increase over check 17.7 15.5

Minikit trial 65 6.3 (min range: 3.9-6.1 t ha -1 ; max range: 6.1-9.1 t ha -1 )

Overall mean 320 5.7 5.4 5.2 5.2 4.5 4.6 performance % increase over check 5.6 9.6 9.6 26.7 23.9

(1992-94)

ASD20 is resistant to stem borer, 68.5% (IR50 has 66.9%); 1000-grain leaffolder, and sheath rot and mode- weight is 22.1 g. rately resistant to blast and rice tungro ASD20 is a best alternative to IR50 virus. The rice is long, slender, and and suitable for April to July, October to white with good cooking quality. Pro- November, and December to January tein content (8.0%) is higher than that of sowings throughout Tamil Nadu, IR50 (7.6%). Its milling recovery is India.

Padmanath: an improved deepwater rice in Assam, India

N. K. Sarma, B. N. Medhi, R. K. S. M. Baruah, B. K. Rao, D. K. Sarma, M. K. Saikia, L. P. Upadhaya, H. Talukdar, and H. N. Gogoi, Regional Agricultural Research Station, Assam Agricultural University, North Lakhimpur, Assam 787001, India

Deepwater rice varieties in Assam (51- 100 cm) are mostly indigenous to the state, require 5-8 mo to mature, encoun- ter occasional droughts and floods up to 3-4 m, and possess genes for stem

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elongation and/or submergence tolerance. The average yielding ability of these indigenous types is very low (1.1 t ha -1 ).

We developed a new deepwater variety, Padmanath, by the bulk pedigree selection method after hybridization among Pankaj/Jagannath//Neg- heribao. Pankaj and Jagannath are improved high-yielding varieties adapted to waterlogged situations, and Neghe- ribao is a local deepwater rice variety with stem elongation capacity in response to rising water level, tolerating flood up to 3-4 m.

The yield records of Padmanath are presented in the table. The average grain yield was 2.7 t ha -1 over years and locations in the state. Padmanath showed 17% superiority over the check variety Amonabao and 49% over its deepwater rice parent Negheribao. Padmanath was also evaluated in the National Deepwater Rice Yield Trials (PVT 6) during 1989 under the name IET11876, and had 85% submergence survival rate, stem elongation score 3,

Chinsurah, Ghagharaghat, and North Lakhimpur as compared with the

and yield of 2.6 t ha -1 over Pusa,

Integrated germplasm improvement — irrigated

Integrated germplasm improvement — flood-prone

28 IRRN 1997

Mean yield performances of Padmanath. Assam, India, 1985-95.

Year Location Yield (t ha -1 )

Pad- Neghe- Amona- rnanath ribao bao

1985 1986

1987

1988

1989

1991

1992

1994 1995

Garumnuria Garumuria Korson Dhalpur Majuli Garurnuria Korson Dhalpur Jorhat Garurnuria Kalabari Dhalpur Dhemaji Dhakuakhana Jorhat Garumuria Dhemaji Dhakuakhana Garumuria Korson Garumuria Mahaijan Garumuria Garumuria Dolpota Dhakuakhana Ghilamora

3.2 2.7 2.8 3.0 2.7 3.0 2.1 2.7 3.3 2.5 3.1 3.2 2.3 2.8 3.2 2.2 3.0 3.1 2.1 2.6 3.3 2.4 2.9 3.4 2.0 2.8 2.9 2.1 2.3 3.1 2.5 1.6 1.1 3.2 3.4 1.7 1.7 1.9 3.1 1.8 2.2 3.0 3.2 1.1 0.6 3.1 1.4 1.7 1.3 1.1 1.6 1.2 3.7 2.7 1.2 0.9 2.0 1.8 2.1 1.2 3.0 1.5

Pooled av over 2.7 1.8 2.3 years and locations

national check Jalamagna with 100% survival, stem elongation score 1, and yield of 2.1 t ha -1 , respectively. Padma- nath is photoperiod-sensitive and flowers in late October. It is recom- mended for cultivation in flood-prone lowlands and deeply flooded regions of up to 2 m water in Assam. Padma- nath exhibited moderate field tolerance for the major diseases and pests of deepwater rice. Good stem elongation up to 24.8 cm d -1 was also recorded in rising floods. The variety also possesses excellent kneeing ability (38° average for all tillers).

Padmanath has medium-bold awned grains of the dimensions 7.4 × 3.1 mm and a test weight of 26.4 g for 1000 grains. The kernels are white and nonglutinous with a length-breadth ratio of 2.8. It is gaining popularity among the deepwater rice farmers of the state.

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Panindra: a new deepwater rice for Assam, India

N. K. Sarma, B. N. Medhi, R. K. S. M. Baruah, M. J. B. K. Rao, D. K. Sarma, L. P. Upadhaya, H. Talukdar, R. Borgohain, M. K. Saikia, and H. N. Gogoi, Regional Agricultural Research Station, Assam Agricultural University, North Lakhimpur, Assam 787001, India

Besides Padmanath, a new deepwater rice variety, we bred Panindra by the bulk pedigree method after hybridization between Pankaj and Negheribao. Pankaj is an improved high-yielding rice variety adapted to waterlogged situations and Negheribao is a local deepwater rice variety with excellent stem elongation capacity under rising floods up to 3-4 m.

The yield data of Panindra from 1988 to 1995 over 13 locations of the state are presented in the table. Panin- dra had a mean grain yield of 2.5 t ha -1

over years and locations, exhibiting 33% superiority in yield than the local check variety Amonabao. Panindra was also found superior in grain yield by 50% than its deepwater parent Neg- heribao. Panindra is tall, elongating with medium slender grains, and suitable to grow in 1-2 m floods in Assam. The variety was also tested in the Na- tional Deepwater Rice Yield Trials (PVT6) under the name IET11875 from 1989 to 1993. During 1989, Panindra had a mean yield of 2.0 t ha -1 as compared with the national check variety Jalamagna, which had the mean yield of 2.2 t ha -1 across locations over India in PVT6.

Ranjini (MO 12): a high-yielding rice variety with blast and brown planthopper resistance

R. Devika, N. Remabai, A. Regina, and S. L. Kumari, Rice Research Station (RRS), Kerala Agricultural University, Moncompu, Thekkekara, P. O. Alappuzha, Kerala 688530, India

Mean paddy yield of Panindra. Assam, India, 1988- 95.

Year Location Yield (t ha1)

1988 1990 1991 1992

1993 1994

1995

Garumuria Korson Garumuria Garumuria Mohaijan Garumuria Garumuria Dolpota Garumuria Dolpota Dhakuakhana Ghilamora Dhemaji

Pooled av

Panin- Neghe- Amona- dra ribao bao

4.2 2.1 2.3 4.1 2.9 1.7 0.6 1.9 1.1 2.9 1.2 2.3 2.0 1.9 3.1 2.7 3.0 2.3 1.1 0.9 1.1 1.8 2.6 1.2 2.4 1.5 2.5 2.2

2.5 1.7 1.9

During 1990, Panindra had exhibited a mean yield of 2 t ha -1 over India under IVT-DW; during 1992 it ranked second to Ghaghraghat (3.3 t ha -1 ) and was superior to Jalamagna (1.8 t ha -1 ).

variety, flowering by the last week of October in Assam. It is moderately tolerant of major diseases and pests but moderately susceptible to rice stem nematode, Ditylenchus angustus. It has outyielded the local deepwater rice varieties of Assam in plant and grain characters. Fair stem elongation rate (21 cm d -1 ) was also observed for Panindra. Excellent kneeing ability (41°) of the tillers after the flood was also an added advantage to this variety.

Awnless grain of Panindra has a dimension of 7.8 × 2.6 mm with a test weight of 24.3 g for 1000 grains. The nonglutinous white kernel has a length-breadth ratio of 3.0.

Panindra is a photoperiod-sensitive

Rice blast is one of the most serious diseases prevalent in Kuttanadu, the rice bowl of Kerala, a unique deltaic area, 0.5-2.0 m below MSL. Many popular high-yielding varieties of this locality lack blast resistance. A hybridization program was started at RRS, Moncompu, using locally accepted, high-yielding varieties, such as MO 5 and blast-resistant varieties such as

Vol. 22, No. 2 29

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Table 1. Yield performance of Ranjini. Kerala, India.

Trial Grain yield (t ha -1 )

Ranjini Check a

RRS, Moncompu (1990-92) (3 seasons) 4.5 3.1 Multilocation trials (MLT) (6 research stations, 1991) 3.2 2.7 MLT (cultivators' fields in five locations, 1992) 5.6 3.2 All India Coordinated Trials

Farm trlals in five locations (IVT-IME, 1993) 4.5 4.0

4.7 3.8

a Check variety was Asha at RRS, MLT, and farm trials; it was Retna for IVT-IME.

Table 2. Reaction of Ranjini to pests and diseases. a RRS, Moncompu, Kerala, India.

Variety Gall midge BPH Sheath blight Sheath rot Blast

Ranjini 1.2 1.0 1.6 2.3 0.8 MO 5 (Asha) 3.2 1.6 3.0 3.1 5.0

a Scored by Standard evaluation system for rice (SES) on a scale of 0-9.

Improved Sona. The breeding line KAU M 28-1-1 (IET13706) from the cross MO 5/Improved Sona performed well in yield trials and was released as Ranjini (MO 12) in 1966 for use in the three seasons of Kerala (virippu, Apr- May to Aug-Sep; mundakan, Sep-Oct to Dec-Jan; and punja, Dec-Jan to Mar- Apr). It is a short-duration (115-120 d),

dwarf (90-95 cm) variety with red- kernel medium-bold grains, and resistant to blast and brown planthopper (BPH).

In yield trials, Ranjini consistently outyielded local checks (Table 1). It also showed tolerance for gall midge, sheath blight, and sheath rot (Table 2).

On-farm seed priming to accelerate germination in rainfed, dry- seeded rice

D. Harris, Centre for Arid Zone Studies, University of Wales, Bangor, Gwynedd, LL57 2UW, UK; and M. Jones, West Africa Rice Development Association (WARDA), Bouak, C te d'Ivoire

Demand for rice is increasing in West Africa, but farmers in upland rice areas face the twin constraints of drought and competition with weeds. Fast germination, establishment, and vigorous early growth of seedlings are essential to produce reasonable yields, particularly where presowing tillage and seedbed preparation are minimal.

Recent work at WARDA has produced interspecific hybrids by crossing Oryza sativa and O. glaberrima to give new plant types that offer high production potential allied to fast germination and enhanced weed suppression. Other work on improving the establishment of small-grained cereals, including rice in India, suggests that simple practices, such as soaking seed in water before sowing (on-farm seed priming), very effectively improve crop establishment. Combining fast-germinating varieties with on-farm seed priming should be of great benefit to rice

Effect of seed priming on germination. Numbers on columns are hours saved by priming.

farmers in marginal environments. We tested 11 different varieties for

their response to soaking in water for 24 h at 30 °C (see table). After soaking, the seeds were surface-dried with a cloth and then “sown” on moistened filter paper and kept at 30 °C. The figure compares the germination time for these primed seeds to nonprimed seeds. All lines responded positively to priming for 24 h, a limit previously determined as safe (i.e., not leading irreversibly to germination after surface drying) in Indian rice cultivars. The mean time for 50% germination of nonprimed seed was 46 h, which was reduced to 32 h by priming. The time saved by priming ranged from 7 h in CG20, an O. glaberrima variety, to 20 h in

Names and plant types of varieties in the figure.

Number in Variety Type figure

1 WAB 56-50 Improved O. sativa 2 WAB 56-104 Improved O. sativa 3 WABC 165 Improved O. sativa 4 CG 14 O. glaberrima 5 CG 20 O. glaberrima 6 WAB 450-24-3- O. sativa/O. glaberrirna

2-P18-HB 7 WAB 450-1- O. sativa/O. glaberrima

B-P-106-HB 8 WAB 450-24-2- O. sativa/O. glaberrima

9 LAC 23 Traditional O. sativa 10 Moroberekan Traditional O. sativa

3-P33-HB

11 SP 4 Traditional O. sativa

SP4, a traditional O. sativa variety.

seed priming in India has shown that farmers prefer to soak their seeds for less than 24 h to avoid the possibility of premature germination if sowing is delayed for any reason. They report a range of benefits following overnight soaking, and our preliminary tests of germination following priming for 8 and 16 h support this conclusion. Further research is in progress to quantify the benefits of seed priming under West African conditions.

Participatory research using on-farm

Comments. If you have comments or

write to the editor. suggestions about the IRRN, please

Seed technology

30 IRRN 1997

Crop and resource management -

(during puddling). Two rows of each genotype were fully sprayed with 100 ppm of GA 3 at 20 and 45 d after planting. Morphological and growth characters were recorded at heading, and dry weights of plant parts were recorded after drying the plant samples in a hot air oven at 70 °C for 72 h.

Rice genotypes responded differently to exogenous GA 3 (Tables 1 and 2). The superdwarf Dwarf mutant reacted the most, by dwarf Cigar and semi-tall Dee-geo-woo-gen. The semidwarf line Nadula dwarf and tall cultivar C14-8 showed negligible growth response. GA 3 stimulated the vertical growth (height) in responsive genotypes, but suppressed their horizontal growth (tiller production, leaf breadth). Exo- genous GA 3 caused drastic stimulation of leaf sheath, blade, lower (rudimentary) internodes, and panicle elongation in Dwarf mutant. This growth

Growth response of diverse rice genotypes to exogenous application of GA 3

S. Singh and T. Ram, Central Agricultural Research Institute, Port Blair 744101, India

Although exogenous gibberellin (GA) usually breaks dwarfism, some cereal genotypes do not respond because they have a higher level of endogenous GA. This study examined the growth response to exogenous GA of rice genotypes with different statures and sources of dwarfism. The rice genotypes included a Dwarf mutant (superdwarf), dwarf Cigar, Nadula dwarf (semidwarf), Dee-geo-woo-gen (semidwarf), and C14-8 (tall). Seedlings (25 d old) were transplanted separately in the ricefield at 40- × 20-cm spacing during the wet season. A full dose of NPK was applied before transplanting

Table 1. Effect of exogenous GA 3 on morphological and growth characters of diverse rice varieties at heading.

Variety/ Plant Culm Panicle Tillers Leaf area Average Average Leaf treatment height length length plant -1 tlller -1 length of width of weight

(cm) (cm) (cm) (no.) (cm 2 ) leaf blade leaf blade ratio a

(cm) (cm)

Dwarf mutant Control 54 42 12 32 117 20.4 1.69 0.35

% of control 230 251 151 75 180 203 76 57 GA 3 123 105 18 24 211 41.5 1.29 0.20

Cigar Control 49 30 19 13 150 27.0 1.57 0.34

% of control 64 140 114 92 104 146 105 70 GA 3 64 42 22 12 156 39.4 1.66 0.23

Nadula dwarf Control 75 58 17 12 509 51.0 2.28 0.31

% of control 103 104 100 92 92 114 88 97 GA 3 77 60 17 11 471 58.4 2.01 0.30

Dee-geo-woo-gen Control 100 73 26 12 346 54.5 1.52 0.39

% of control 127 142 85 100 75 105 92 72 GA 3 127 104 23 12 260 57.5 1.40 0.28

C14-8 Control 188 159 29.0 12 480 71.0 1.60 0.24

% of control 107 108 100 108 92 106 103 104 GA 3 202 172 29.0 13 441 75.0 1.65 0.25

a Leaf weight Total dry weight

enhanced the final stature of plants. GA 3 also caused greater enhancement in the size of individual leaf, leaf area per tiller and plant, and gravimetric growth of various plant parts (stem, leaf, and panicle) in GA 3 -responsive genotypes. The ratio of leaf weight to total plant weight, leaf width, and tiller production were reduced markedly by exogenous GA 3 in responsive genotypes. GA 3 caused greater stimulation of stem growth than that of leaf growth (Table 2). In general, the morphological and growth effects of GA 3 were greater in dwarf genotypes than in semi-tall and tall ones, but an exception was noted in the semidwarf line Nadula dwarf. GA 3 enhanced the number of elongated internodes (mainly lower rudimentary) but not the total number of internodes per plant (Table 2). The elongation effect of GA 3 was greater in lower internodes than in upper internodes.

Dry weight plant -1 (g) Dry weight tiller -1 (g)

Stem Leaf Panicle Total

15.1 12.1 7.2 348 1.08 48.8 16.1 8.8 79.5 3.31

323 323 122 228 306

8.0 8.0 7.6 23.2 1.78 13.3 7.2 14.6 29.2 2.43

166 90 192 126 134

43.1 25.3 12.0 80.4 6.70 38.9 22.2 13.0 79.0 6.72 90 88 108 92 100

24.3 19.0 5.0 48.3 4.02 33.0 16.0 7.2 56.1 4.67

135 84 144 116 116

76.7 29.1 13.4 131.6 10.0 95.3 37.5 17.4 150.0 11.6

124 128 130 126 116

Plant physiology

Vol. 22, No. 2 31

Table 2. Effect of exogenous GA 3 on elongation of internodes and leaf sheath and expansion of leaf blade in rice varieties.

Variety/ Length of internode from top (cm) Length of leaf sheath from top (cm) treatment

Area of individual leaf from top (cm 2 )

I II IV V I II III IV V I II III IV V III

Dwarf mutant Control 26 12 3 1 1 16 11 9 8 9 27 27 26 27 18

% of control 127 91 533 2900 1500 218 318 288 187 267 170 167 138 155 206 GA 3 33 11 16 29 15 35 35 26 15 24 46 45 36 42 39

Cigar Control 16 10 3 1 1 20 12 12 11 9 48 47 33 22 15

% of control 112 130 200 200 200 115 117 83 127 111 114 117 124 86 -GA 3 18 13 6 3 2 23 14 10 14 10 55 55 41 19 -

Nadula dwarf Control 25 11 12 7 3 23 16 18 18 19 79 100 104 91 81

% of control 88 72 125 86 300 100 87 88 122 121 101 88 104 97 82 GA 3 22 8 15 6 9 23 14 16 22 23 80 88 108 89 66

Dee-geo-woo-gen Control 31 14 16 8 6 36 26 27 23 26 56 80 79 67 46

% of control 96 114 112 275 150 97 130 96 104 92 87 95 83 85 121 GA 3 30 16 18 30 10 35 34 26 24 24 49 76 66 57 56

C14-8 Control 39 34 25 20 14 42 32 31 34 39 69 90 104 110 89

% of control 107 103 112 140 128 95 106 100 85 107 104 112 101 104 110 GA 3 42 35 28 28 18 40 34 31 29 42 72 101 106 114 98

Effect of low light stress on photosynthesis, dry matter production, and grain yield in rice hybrids bred from two different cytoplasmic male sterile sources

M. J. Baig, P. Swain, and K. S. Murty, Central Rice Research Institute, Cuttack 753006, India

We compared the tolerance for low light of selected F 1 rice hybrids bred from two cytoplasmic male sterile (CMS) lines, IR62829A and IR58025A, during wet season in 1992 (see table). They were grown in 3-m 2 field plots at 15- × 10-cm spacing and fertilized with 60 kg N ha -1 . Wooden screens were used to create low light (50% of normal sun-light) from 35 d after transplanting until harvest. Controls were maintained under normal sunlight (about 340 cal cm -2 d -1 ). The split-plot design with three replications was used with the two light treatments in the main

Effect of shading on photosynthesis and yield in hybrids and restorers. Cuttack, India. a

Pn TDM Yield Hybrid/restorer (mg CO 2 dm -2 h -1 ) (g m -2 ) (g m -2 )

L S L S L S

lR62829 A/Swarna 41.6 29.1 1043 666 365 232 lR62829 A/Vajram 51.8 29.3 1377 818 665 269 lR58025 A/Swarna 51.6 29.2 952 582 356 167 lR58025 A/Vajram 37.4 25.4 947 695 352 176

Restorers Swarna 31.2 18.8 968 455 432 170 Vajram 48.5 30.7 1326 746 522 228

Standard Swarnaprabha 45.9 35.2 1141 703 520 218

Mean 44.0 28.2 1108 666 459 209

CD (5%) Variety (V) 0.71 54 22 Treatment (T) 4.36 54 24 V at same T 6.16 95 34 T at same V 5.77 76 45

Heterosis (%) over restorer lR62829 A/Swarna 33 55 8 46 -16 36 lR62829 A/Vajram 7 -5 4 10 27 18 lR58025 A/Swarna 51 55 -2 28 -18 -2 lR58025 A/Vajram -23 -17 -29 -7 -33 -23

Mean 17 22 -5 19 -10 7

HI (%)

L S

35 35 48 33 38 35 37 26

45 37 39 31

46 31 41 33

3.4 2.3 5.2 4.8

-22 26

-8 6

-15 -8 -5 -16 -4 -7

plots and the hybrids in the subplots. The photosynthetic rate (Pn) of the

a Pn = photosynthetic rate, TDM = total dry matter, HI = harvest index, L = light, S = shaded.

Physiology and plant nutrition

32 IRRN 1997

second leaf at vegetative stage (40 d after planting) and the flag leaf at flowering was measured using a portable LI-6000 at near saturated light (above 1000 µE m -2 s -1 ). The hybrid IR62829A / Vajram showed highest Pn values but marginal (positive) and negative heterosis over restorers in light and shade, respectively. Swarna registered higher heterosis (over restorer) in Pn under both light and shade. The combining ability for Pn seems to be better with IR62829A for Vajram and IR58025A for Swarna.

Estimation of elongation efficiency in deepwater rice varieties

P. M. Mohapatra and A. R. Panda, Plant Breeding and Genetics Division, Central Rice Research Institute, Cuttack 753006, Orissa, India

When submerged, deepwater rice shows rapid elongation of internode, leaf sheath, and leaf blade, the amount depending on variety. We studied 15 deepwater varieties for their relative elongation efficiency during the 1996 wet season at Cuttack. Three pots with two 37-d-old plants of each variety were submerged in a 110-cm deepwater tank. On the first day, water level was maintained at 40 cm, and on the following day it was raised to 110 cm. The height of plants was recorded before submergence and every 2 d during submergence, up to 10 d. The relative elongation efficiency indices of the varieties were calculated by the formula suggested by Singh (1982):

where X 1 , X 2 , X 3 , X 4 , and X 5 stand for actual elongation (in cm) during first, second, third, fourth, and fifth observation, respectively, N is the total span in days (10) from submergence to last observation.

Total dry matter (TDM) and grain yield were highest in the F 1 hybrids of IR62829A and the restorer Vajram. Harvest index was high in IR62829A / Vajram (only in light), whereas Swarna had higher values. The hybrid IR52829A/Vajram showed higher dry matter, yield, and harvest index than the standard check Swarnaprabha.

yield was found in the hybrids of the IR62829A CMS line under shade, whereas under light marginal heterosis was observed for TDM only. The

High positive heterosis for TDM and

hybrids of IR58025A CMS line showed negative heterosis for yield and harvest index under both light and shade regimes (except IR58025A/Swarna for TDM under shade). The hybrid IR62829A / Swarna showed high heterosis for TDM and yield under shade; under normal light IR62829A/ Vajram recorded higher values for yield and harvest index, but this hybrid showed higher grain yield under both conditions, indicating its agronomic superiority in yield with greater harvest index.

Actual elongation of 15 varieties after submersion for 10 d.

Actual elongation (cm 48 h -1 ) Variety

X 1 X 2 X 3 X 4 X 5

Jalamagna TCA4 Jalanidhi NDGR410 Kariawa LPR56-49 TCA282 TCA269 Madhukar NDGR413 TCA12 Chakia 59 Jalapriya Bojaz LPR85

25.8 13.8 21.8 15.5 10.2 7.6 17.8 20.6 16.8 13.4

6.2 6.2 13.4 13.4 12.0 8.6

9.0 9.8 13.0 16.4 12.6 12.0 8.4 9.4 8.8 6.0

12.2 8.4 4.70 5.1

11.6 10.8 12.0 8.5 22.6 11.1 21.1 5.2

9.0 16.3 11.8 4.0 17.0 4.7 22.6 8.0 12.2 8.0 13.6 11.0 16.4 8.5 22.2 4.3 13.6 7.2 21.6 2.8 24.4 5.5

9.4 8.5

15.5 2.8

15.3 7.3 5.6 7.0 7.1 9.8 7.1 2.6 5.6 2.3 4.5

Total (cm)

71.4 66.3 67.0 67.5 70.8 35.5 54.1 58.2 46.1 63.8 56.6 46.9 41.2 47.3 44.2

Elongation efficiency

index

0.70 0.65 0.52 0.69 0.59 0.30 0.52 0.52 0.40 0.57 0.52 0.44 0.36 0.47 0.37

Jalamagna had the highest elongation efficiency index (0.70), followed by NDGR410 (0.69), TCA4 (0.65), and Histological variation among Kariawa (0.59) (see table). The higher aromatic rice indices of the above varieties might be attributed to attainment of maximum L. P. Awasthi, A. K. Sharma, and D. M. Maurya, rate of elongation at an early stage Genetics and Plant Breeding Department, (higher X 1 values), except for NDGR410, Narendra Deva University of Agriculture and which had consistently high elongation Technology Kumarganj, Faizabad 224229, Uttar rates up to the third observation (high Pradesh, India X 1 , X 2 , and X 3 values). Most of the varieties attained maxi-mum elongation Fifteen popular aromatic genotypes rate after 6 d of sub-mergence (higher X 3 were studied to ascertain the variation values) and had comparatively low for histological traits in leaves and elongation efficiency indices. The shoots. Photomicrographs of the varieties with elongation efficiency transverse sections of leaves revealed indices higher than 0.44 managed to that the cuticle in all genotypes was

below 0.44 remained submerged. nonaromatic check, Mahsuri. The size penetrate the water surface while those thin compared with that of the

Vol. 22, No. 2 33

of metaxylem, protoxylem, and phloem elements bundle were highly variable, Large metaxylem (50-60 nm), protoxylem (40-50 nm), and phloem (20-25 nm) were observed in mild aromatic genotypes (Adamchini, Kesar, Lalmati, and T3). They were of medium size in the nonaromatic check and in moderately aromatic genotypes (Kanakjeer, N12, Pusa 33, Sakkar chini A, T3, T9, and Tilak Chandan) and small in strongly aromatic genotypes (Basmati 370, Kalanamak, Kasturi, Phool Chameli A, and Pusa Basmati 1). Most of the genotypes had small- to medium-sized companion cells in the phloem.

Mesophyll cells of Basmati 370, Kalanamak, Kasturi, and Pusa Basmati 1 were extremely swollen, with fewer intercellular spaces than those in the other genotypes. The parenchymatous cells of the midrib were highly enlarged and resembled vesicles. Abnormal thickening of mesophyll and a slight protrusion of cell walls were also observed. Such cells were not so visible in the mildly aromatic genotypes as well as in the nonaromatic check Mahsuri (Fig. 1).

Transverse sections of shoots exhibited little genetic variation for thickness of cuticle, appearance of ground tissue, and pith. However, the number of cell layers in the hypodermis and the degree of lignification were highly variable. Kanakjeer and Pusa Basmati 1 possessed highly lignified hypodermis.

The number of vascular bundles varied greatly. Adamchini had up to 75 bundles and T9 up to 45. In strongly aromatic genotypes (Basmati 370, Kalanamak, Kasturi, and Pusa Basmati l), normal phloem and xylem elements were replaced by a largely undiffer- entiated parenchymatous cell mass. Abnormal amounts of xylem tissue were produced with a large number of abnormal sieve elements. On the other hand, mildly aromatic genotypes and the nonaromatic check Mahsuri were free of this histological peculiarity (Fig. 2).

1. Photomicrograph of transverse section of leaf. a. Aromatic genotype Basmati 370. b. Nonaromatic genotype Mahsuri.

2. Photomicrograph of transverse section of shoots. a. Aromatic genotype Basmati 370. b. Nonaromatic genotype Mahsuri.

Preliminary studies on response of a rice-based crop sequence to S and Zn in temperate Kashmir, India

B. Hasan, S. K. University of Agricultural Sciences and Technology, c/o P. O. Box 706, G. P. O., Srinagar Kashmir 190001, India

This study varied levels and frequencies of S and Zn applications to determine effects on crop yields in a rice - rapeseed cropping pattern. It started in summer 1992, using a rice crop followed by rapeseed until winter 1994 at the university's Shalimar Research Farm (1587 m msl). The soil is an Alfisol (Hapludalf) silty clay loam, pH 6.8, organic C 0.37%, low in available N (alkaline permanganate method), low in available P (Olsen's method), and medium in available K (1 N neutral ammonium acetate method). It con-

tained 9 ppm available S (ammonium acetate-acetic method) and 0.66 mg kg -1 Zn (DTPA extractable).

A randomized block design with four replications was used. The treatments consisted of a control plot (NPK applied at 80-26.2-33.2 kg ha -1 ), two levels of S (10 and 20 kg ha -1 as calcium sulfate dehydrate), and three levels of Zn (3, 6, and 9 kg ha -1 as zinc oxide). A traditional variety K39 (SK5) of transplanted rice was used. Sulfur and Zn were applied basally along with recom- mended levels of NPK to each rice crop.

Application of S or Zn with NPK resulted in significant increase in grain yield over the control (see table). During 1992, rice grain yield was maximum (4.02 t ha -1 ) at 10 kg S ha -1 , whereas rapeseed yield was highest (1.26 t ha -1 ) at 20 kg S ha -1 applied to the previous rice crop. Both S and Zn had significant residual effect on the succeeding crop of rapeseed. This re-

Fertilizer management—inorganic sources

34 IRRN 1997

Fertilizer management—organic sources Effect of organic and inorganic fertilizers on sustainability of soil fertility and grain yield in a rice - wheat system

D. K. Gupta and J. P. Gupta, Regional Agriculture Research Station (RARS), S. K. University of Agricultural Sciences and Technology, R. S. Pura, Jammu, 181102, India

We used inorganic fertilizers with organic amendments (farmyard manure [FYM], rice straw) and green manure

(GM) with dhaincha (Sesbania aculeata) to study yield, NPK uptake, and soil fertility.

The experiment began in 1985 at this station in the Jammu region. The soil is a clay loam Inceptisol with pH 7.1, EC 0.16 dS m -1 , 0.62% organic C, and 456.0 kg available N ha -1 , 13.80 kg P ha -1 , and 154 kg K ha -1 . Average N content (oven dry basis) was 0.71 % in FYM, 1.02% in dhaincha, and 0.36% in rice straw. The treatments were replicated four times in a randomized block design.

Rice variety Jaya was planted during the first week of July every year at 20- × 15-cm spacing. The 45-d-old GM crops were chopped and incorporated in the field 25 d before transplanting. The FYM and rice straw were mixed into the soil 15 d before transplanting. Plots were irrigated and 30-d-old rice seedlings transplanted in the puddled field. A wheat crop (variety HD2329) was sown during the third week of Novem- ber every year at the rate of 100 kg seeds ha -1 and chemically fertilized as required (Table 1).

sponse was attributed to the inherently low level of these nutrients in the soil and to improved fertilizer N use efficiency resulting from their application.

The frequency of S or Zn application had no significant effect on rice yield. Rapeseed yields, however, were highest with 3 and 6 kg Zn ha -1 every year. It was concluded that S and Zn should be applied to rice to obtain enhanced yields with an application frequency of 10 kg S ha -1 in alternate years along with 3 or 6 kg Zn ha -1 every year. This practice should prove advantageous over the years in realizing higher output from this important crop sequence in the Kashmir Valley.

Effect of S and Zn on yield in a rice-based cropping system in temperate Kashmir, India.

Grain yield (t ha -1 )

Treatment Summer crop (rice) Winter crop (rapeseed)

1992 a 1993 1994 Mean b 1992-93 a 1993-94

Control (NPK only) 2.8 4.6 4.5 4.6 0.9 1.0 NPK + 10 kg S, E 4.0 6.2 4.8 5.5 1.0 1.4 NPK + 10 kg S, A - c 6.1 5.0 5.6 1.3 NPK + 20 kg S, E 3.8 5.6 5.0 5.3 1.3 1.5 NPK + 20 kg S, A 5.9 5.1 5.5 1.3 NPK + 3 kg Zn, E 3.0 5.3 4.8 5.0 1.1 1.3 NPK + 3 kg Zn, A 5.6 4.8 5.2 1.1 NPK + 6 kg Zn, E 3.5 5.4 4.8 5.1 1.1 1.6 NPK + 6 kg Zn, A 5.6 4.9 5.3 1.3 NPK + 9 kg Zn, E 3.3 5.8 5.0 5.4 1.3 1.3 NPK + 9 kg Zn, A 5.2 5.1 5.1 1.1

a Since this was the first year of experimentation, every (E) and alternate (A) years' values have been pooled and the means reported. b Means of 1993 and 1994. c = no data.

Table 1. Grain yield (t ha -1 ) as influenced by different treatments in rice - wheat cropping system. Jammu, India, 1985-93.

Treatment a 1985-87 1988-90 1991-93

Rice Wheat Total Rice Wheat Total Rice Wheat Total

Kharif

T1 Control T2 50% F T3 50% F T4 75% F T5 100% F b

T6 50% F + 50% FYM T7 75% F + 25% FYM T8 50% F + 50% rice straw T9 75% F + 25% rice straw T10 50% F + 50% GM T11 75% F + 25% GM T12 Conventional c

CD (5%)

Rabi

Control 50% F 100% F 75% F 100% 100% F 75% F 100% F 75% F 100% F 75% F Conventional

3.2 3.6 4.2 4.5 4.9 4.4 4.8 4.1 4.7 4.5 4.7 3.6

0.2

1.5 2.4 3.1 2.8 3.2 3.4 2.8 3.0 2.9 3.3 3.0 2.0

0.3

4.7 6.0 7.3 7.3 8.1 7.8 7.5 7.1 7.5 7.8 7.7 5.6

2.6 1.2 3.8 3.7 2.5 6.1 3.8 3.5 7.3 4.0 3.0 7.0 4.4 3.6 8.0 4.2 3.8 8.0 4.4 3.2 7.6 4.1 3.5 7.6 4.4 3.3 7.7 4.2 3.7 7.8 4.4 3.3 7.6 3.1 1.8 4.9

0.1 0.1

2.7 1.2 3.9 3.5 2.4 5.9 3.7 2.9 6.5 4.0 2.6 6.6 4.6 3.1 7.7 4.9 3.3 8.1 4.7 2.9 7.6 4.1 3.1 7.1 4.3 2.8 7.1 4.7 3.1 7.8 4.7 2.9 7.6 3.5 1.8 5.3

0.1 0.1

a F = inorganic fertilizer; FYM = farmyard manure; GM = green manure (dhaincha). b 100% F = rice (100 kg N, 26.4 kg P, and 24.9 kg K ha -1 ); wheat (100 kg N, 22.0 kg P, and 20.7 kg K ha -1 ). c Conventional = farmer's practice of applying 60 kg DAP ha -1 (basal) and 60 kg urea ha -1 (topdressed).

Vol. 22, No. 2 35

LSD (P = 0.05) 0.3 0.7 0.2 - 0.1 0.2

- -

-

-

-

-

-

-

-

-

-

-

At first, highest grain yield of rice and wheat during kharif was obtained with T5 (100% NPK through fertilizer). The treatments T7 (75% NPK + 25% N [FYM]), T9 (75% NPK + 25% N [straw]), and T11 (75% NPK + 25% N [GM] gave higher rice yields than T6 (50% NPK + 50% N [FYM]), T8 (50% NPK + 50% N [straw]), and T10 (50% NPK + 50% N [GM]). During rabi, T6, T8, and T10 produced higher wheat yield than T7, T9, and T10, a result that may be attri-

productivity over the years in treatments T6 and T10 was comparable with that of T5.

Available N, P, and K (Table 2) decreased over the control after conventional treatment. Minimum depletion of N was observed in treatment T7 during kharif followed by T5 (100% NPK through chemical fertilizers in both seasons), T11, and T10.

Available P also decreased over the years, except for T5, where an apprecia-

buted to 25% less NPK. The control ble buildup was observed. Available K recorded the lowest yield, and declined content decreased in all treatments and over the years. In later years, T6 and maximum depletion was observed in T10 have shown the highest response the control. over the control, indicating that a 50% These results suggest that combined NPK saving could be achieved by use of organic and inorganic fertilizers continuous application of FYM or GM can sustain soil fertility and grain yields during kharif. Treatments T7 and T11 in rice - wheat cropping systems. showed a 25% NPK saving. Total mean

Table 2. Effect of integrated nutrient supply on soil fertility changes under rice - wheat cropping system. Jammu, India, 1992-93.

Available nutrients (kg ha -1 ) after 8 yr

ment 1992 kharif 1992-93 rabi no. a

Treat-

N P K N P K

T1 179.2 5.42 87.0 162.0 5.10 82.5 T2 224.0 8.10 94.0 213.7 7.40 9 1.0 T3 251.0 8.80 94.5 247.5 8.25 91.0 T4 245.7 11.90 88.2 237.5 10.60 91.0 T5 310.2 20.40 101.4 301.0 17.90 97.4 T6 296.5 12.40 97.4 287.5 12.00 97.4 T7 327.0 16.80 102.0 310.5 15.25 97.4 T8 277.0 11.10 102.0 266.5 10.60 97.4 T9 278.0 11.10 98.5 271.1 10.85 98.5 T10 296.5 11.10 98.5 292.3 10.60 97.4 T11 301.0 10.90 87.2 292.3 10.60 83.5 T12 189.5 6.90 76.5 183.0 6.70 72.2 Initial 456.0 13.80 154.00

a See Table 1 for details.

Effect of foliage pruning on performance of rice under semi-deep water situations (50-100 cm)

A. Ghosh and A. R. Sharma, Central Rice Research Institute, Cuttack, Orissa 753006, India

We studied the response of rice yield to foliage pruning under excess water (>50 cm) at Cuttack during 1995 wet season using Panidhan (semi-tall, 180 d) and LPR312 (tall, 170 d) varieties. They were direct-sown in puddled soil the first week of June at 400 seeds m -1 in 20-cm row spacings with basal fertilizers at 40 kg N ha -1 ,17.6 kg P ha -1 , and 33.2 kg K ha -1 . Foliage was pruned above the joint (collar) of the topmost leaf once or twice at 80,100, and 120 d after germination (DAG). A split-plot design was used, data analyzed by standard analysis of variance, and treatment means were compared at the 5% level.

June, and by the first part of July, water level was 80 cm deep, fluctuating between 35 and 60 cm during crop growth period and receding gradually by crop maturity in mid-December.

Crops emerged the second week of

Foliage pruning influenced plant growth (Table 1). Vertical growth picked up faster after first and second pruning but slowed down after third pruning. LPR312 produced more foliage than did Panidhan. Foliage taken at different times and frequencies differed from one another. Pruning at later growth stages gave more foliage than that at early stages. Interaction

between pruning and variety was not significant. However, LPR312 at delayed pruning gave more foliage than Panidhan. Foliage pruning was found detrimental to panicle growth and development, especially at later growth stages (Table 2). Panicle sterility was 2-3% higher with delayed pruning and two prunings compared with no pruning. Yield response also declined.

Table 1. Plant height and foliage yield of rice varieties at different times and number of leaf prunings.

Plant height (cm) Foliage yield (t ha -1 ) Treatment

80 DAG a 100 DAG 120 DAG Maturity Fresh Dry

Variety Panidhan 119 129 146 150 4.0 1.3 LPR312 116 133 157 164 4.9 1.6 CD (5%) ns ns ns ns 1.3 0.4

Pruning No pruning 116 137 166 174 One pruning at

80 DAG 118 136 163 167 2.9 0.7 100 DAG 121 135 154 160 3.4 0.8 120 DAG 116 124 149 157 4.3 1.4

80 + 100 DAG 116 124 147 161 5.7 1.6 100 + 120 DAG 117 134 154 156 7.0 2.4 80 + 120 DAG 118 125 141 155 6.1 2.0 CD (5%) ns 7.7 10.5 9.4 1.0 0.3

Two prunings at

a DAG - days after germination.

Crop management

IRRN 1997 36

- -

Effect of seed rate, seed density, and nitrogen fertilizer on performance of flood-prone lowland rice

A. Ghosh and A.R. Sharma; Central Rice Research Institute, Cuttack 75300, India

We conducted two experiments during 1994 at Cuttack, India in adjoining fields. In the first, seeds of varying densities were sown at different rates using a common basal dose of 40 kg N ha -1 . Nine treatment combinations were arranged in a factorial randomized complete block design with three replications. In experiment 2, only low- and high-density seeds were grown at 400 and 600 seeds m -2 using 0 and 40 kg N ha -1 . Sixteen treatment combinations were arranged in a split-plot design with three replications, keeping submergence levels in main plots and combinations of seed rate, seed density, and N fertilizer in sub-plots.

Rain began 10 d after sowing, with 10.4, 4.8, and 0.8 mm falling at 2-d

Table 2. Effect of leaf pruning on yield and yield components of rice. Cuttack, India, 1995.

Treatment Panicles m -2 Panicle Grain Straw Panicle (no.) weight (g) yield (t ha -1 ) yield (t ha -1 ) sterility (%)

Variety Panidhan 141 2.61 2.3 7.9 8.4 LPR312 151 2.55 2.3 7.2 8.2

CD (5%) ns ns ns ns ns

Pruning No pruning One pruning at

80 DAG 100 DAG 120 DAG

Two prunings at 80 + 100 DAG

100 + 120 DAG 80 + 120 DAG CD (5%)

160

148 138 143

143 133 136

12

2.73

2.60

2.21

2.36 2.23 2.16

ns

2.84

2.6

2.5 2.5 2.0

2.3 2.0 1.9 0.4

10.2

9.6 8.6 8.6

7.7 7.6 7.1 1.6

5.5

6.5 7.3 8.5

8.3 8.7 8.3 1.1

Early pruning produced more grain Significant reduction was also found yield than delayed pruning. In general, in straw yield at maturity. It was more foliage pruning up to 100 DAG pro- pronounced when foliage was reduced grain yield comparable with that moved twice. One early pruning 80 of no pruning, but pruning thereafter DAG) had no adverse effect on straw reduced grain yield. yield. Pruning delayed after 80 DAG or

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

twice at either of the two growth stages reduced straw yield by 19-21% and 33- 44% respectively, compared with no pruning.

The results suggest that foliage pruning of tall and long-duration rice variety may be used to supplement cattle rations in lowland areas lacking fodder in wet season. However, foliage should be removed at early growth stages, preferably 35-40 d before flowering, in order not to adversely affect grain yield.

Table 1. Growth and yield of rice as influenced by seed rate and seed density in the flood-prone lowlands of Cuttack, India, during 1994 (Experiment 1). a

(%) (cm) (g) (t ha -1 ) (t ha -1 )

Seedling Plant height Panicles m 2 Panicle Grain Straw Treatment emergence at maturity (no.) weight yield yield

20 seeds m -2

19.4 mg 30.4 132 75 2.95 2.0 5.6 21.2 mg 32.2 138 107 3.22 2.7 6.0 22.9 mg 33.1 139 115 3.20 2.9 6.7

19.4 mg 30.4 132 93 2.75 2.3 7.8 21.2 mg 32.7 138 116 2.80 2.7 8.3 22.9 mg 33.5 138 122 2.88 2.8 8.7

19.4 mg 30.3 133 106 2.75 2.5 7.9 21.2 mg 32.6 135 127 2.74 2.8 8.6 22.9 mg 34.0 138 121 2.85 2.8 8.2

40 seeds m -2

600 seeds m -2

Mean effects Seed rate (m 2 ) 200 31.9 136 99 3.12 2.5 6.1 400 32.2 136 110 2.81 2.6 8.3 600 32.3 135 118 2.78 2.7 8.2

19.4 30.4 132 91 2.82 2.3 7.1 21.2 32.5 138 117 2.92 2.7 7.6 22.9 33.5 137 119 2.98 2.8 7.9

CD (P=0.05) Seed rate ns ns ns 0.25 ns 0.83 Seed density ns 3 ns ns 0.2 ns Interaction ns ns ns ns 0.4 ns

a Gayatri, a semidwarf, long-duration, photoperiod-sensitive, relatively flood-tolerant variety, was used. Crop was direct-sown on 25 May after premonsoon showers at a row spacing of 20 cm using a common basal dose of 8.7 kg P ha -1 and 16.7 kg K ha -1 . Seeds of varying grades were obtained by repeated screening of thoroughly cleaned seeds in a saline solution (sp. gr., 1.2; 300 g common salt L -1 of water).

Seed density (mg)

Vol. 22, No. 2 37

Table 2. Growth and yield of rice as influenced by seed rate (A), seed density (B), and N fertilizer (C ) under natural submergence (SI) and simulated flashflooding (S2) at Cuttack, India, during 1994 (Experiment 2).

Seedling Plant height Panicles m -2 Panicle Grain yield Straw yield Treatment emergence (cm) (no.) weight (g) (t ha ) -1 (t ha -1 )

(%) S1 S2 S1 S2 S1 S2 S1 S2 S1 S2

Seed rate (m -2 ) 400 32.3 125 112 77 67 2.88 2.16 2.5 1.7 4.7 2.7 600 30.9 129 113 82 79 2.71 2.08 2.4 1.9 5.4 3.0

19.4 29.8 126 112 74 68 2.53 2.07 2.3 1.6 4.9 2.4 22.9 33.4 128 113 85 78 3.06 2.17 2.5 1.9 5.3 3.2

0 40

31.5 125 107 76 64 2.68 2.02 2.2 1.6 4.4 2.3

Mean - 127 111 80 73 2.80 2.10 2.4 1.8 5.0 2.8 CD (0.05) Submergence level 13 ns 1 0.33 2.05 Mean effects of A B, or C 3.0 5 5 2 1 1 Interaction (S X A, B, or C) b 6 7 7 0.15 2

Seed density (mg)

N fertilizer (kg ha -1 )

3.18 129 118 83 82 2.91 2.27 2.6 2.0 5.6 3.2

a Same variety and natural conditions as in Table 1. Simulated flashflooding was done in especially constructed tanks at 90±2 cm depth for 10 d continuously at 75 d of growth. b lnteraction between A, B, and C was not significant.

intervals during the second week of duced plant height significantly more June. These conditions resulted in

The ability of N fertilizer to increase delayed and very poor germination than natural submergence (Table 2).

(<35%). Seedling emergence 25 d after plant height was more pronounced sowing was significantly higher in under flashflooding conditions. high-density seeds, but percent In experiment 1, mean grain yield emergence from different seed rates or remained unaffected by increased seed N fertilizer levels were similar (Tables 1 rate because an increase in number of and 2). panicles m -2 at a higher seed rate was

appeared more vigorous and suffered (Table 1). Interaction comparison less from the initial drought. Water revealed that yield increased signifi- built up from the last week of June and cantly with in-creasing seed density, rose rapidly to 30 cm at 18 d after particularly at the lower seed rates of seedling emergence (DE) and 70 cm at 200 and 400 seeds m -2 . Grain yield 34 DE. Subsequent flooding complete- increased up to 600 seeds m -2 with the ly submerged plants for about a week. use of low-density seeds, but the effect However, the relatively taller and from using medium- and high- density vigorous rice plants raised from high- seeds at varying rates was similar. This density seeds and with N fertilizer result suggests that seed rate can be application showed better recovery reduced by using high-density seeds. after the flood receded. Natural Vigorous seedlings not only establish flooding up to 82 cm at the end of well but survive better under drought August also submerged most plants for or flooding; also, plants compensate for more than 10 d. Experiment 2 also the poor crop stand at the lower seed subjected the crop to simulated flash- rate through increased tillering. flooding at the beginning of September In experiment 2, the beneficial effects for 10 d, after which the floodwater of seed rate, seed density, and N fertili- receded gradually. zer were more pronounced under

At crop maturity, the plants from simulated flashflooding than under high-density seeds were taller, but seed natural submergence (Table 2). The rates made no significant difference mean increase in yield from N fertilizer, (Table 1). Artificial flashflooding re- high-density seeds, and higher seed

Plants raised from dense seeds associated with reduced panicle weight

rate was 25.2, 20.9, and 11.8%, respectively under simulated flashflooding conditions. Higher seed rate did not affect yield under natural submergence, but instead yield increased by 15.7 and 8.7% using N fertilizer and high-density seeds. The greater bene-ficial effect of N and high-density seeds was associated with a greater number and weight of panicles. Mean grain yield decreased 25.7% by flashflooding compared with natural submergence, but similar reductions in yield were less with the use of 40 kg N ha -1 (22.9%), high-density seeds (21.6%), and higher seed rate (19.9%) than without N (28.7%), low- density seed (29.9%), and normal seed rate (30.4%), respectively.

of flood-prone lowland rice depends largely on initial crop stand and vigor, which can be improved by using a higher seed rate and plump seeds with basal fertilization. High-density seeds germinate better and produce vigorous seedlings, leading to greater survival under initial drought and flashflooding. These abiotic stresses can also be mitigated by increasing the seed rate and N fertilizer.

We conclude that yield performance

Effect of tillage and fertilizer levels on grain yield and incidence of brown spot disease in rice

R. A. Singh, P. C. Pandey, and B. Das, Plant Pathology and Agronomy Department, G.B. Pant University of Agriculture and Technology, Pantnagar 263145, India

This study was done in kharif 1992 and 1993 at Pantnagar to observe the effect of tillage practices and fertilizer levels on rice production and disease incidence. A split-plot design was used with puddled ‘P’ and unpuddled ‘UP’ as main plots and two fertilizer levels as subplots of 11.8 × 6.0 m. Fertilizer levels were F 1 : 120 kg N ha -1 , 17 kg P ha -1 , and

38 IRRN 1997

33 kg K ha -1 and F 2 : 100 kg N ha -1 , 26 kg P ha -1 , and 50 kg K-h a -1 . In ‘UP’ plots, the seeds of cv Pant Dhan 4 were drilled in 20 cm rows on 20 Jun 1992 and 3 Jul 1993, and in P plots 30-d-old seedlings were transplanted on 23 Jul 1992 and 7 Jul l993 with a spacing of 20 × 15 cm. Phosphorus and potash were given basally and N was applied in three splits, 50% P and 25% UP as basal; 25% P and 50% UP at tillering; and 25% (P and UP) at panicle initiation.

five stools selected at random from each plot according to IRRI’s 1988 Standard evaluation system for rice. The number of shoots at harvest was 360 m -2

(1992) and 390 m -2 (1993) in UP plots compared with 280 m -2 (1992) and 270 m -2 (1993) in P plots. Incidence of brown spot caused by Cochliobolus miyabeanus (Ito and Kuribayashi) Drechsler ex Dastur anamorph Drechslera oryzae (Breda de Hann) Subra and Jain was severe in both seasons. Fertility levels had no significant effect on the severity of brown spot, while tillage significantly

Disease incidence was recorded on

Disease and grain yield (t ha -1 ) in puddled (P) and unpuddled plots (UP) at two fertilizer levels. Pantnagar, India, 1992 and 1993.

Brown spot disease (%) a Yield (t ha -1 ) Treatment

1992 1993 1992 1993

120 kg N + 17 kg P + 19.54 22.2 5.3 5.8 33 kg K ha -1 (P) (26.21) (28.1)

100 kg N + 26 kg P + 17.05 19.4 6.6 6.1 50 kg K ha -1 (P) (24.73) (26.13)

120 kg N + 17 kg P + 30.05 52.7 4.8 4.9 33 kg K ha -1 (UP) (33.21) (46.55)

100 kg N + 26 kg P + 29.43 44.4 5.2 5.8 50 kg K ha -1 (UP) (32.43) (41.78) CD (5%) Tillage 4.33 0.86 0.4 1.7

Fertility ns ns 0.4 1.7 CV 18.48 26.5 10.0 5.0

a Figures in parentheses are angular values.

influenced it. The disease index was significantly in UP plots, an effect significantly lower in P than in UP attributable to their higher plant popu- plots, and the difference more lation. Another reason may be the poor pronounced in 1993 (see table). water management in UP plots with

During kharif 1992, yield was signi- nutritional imbalance in the soil that ficantly higher in both P and UP plots. aggravates the disease. Caution must The yield was also higher in P than in be exercised in recommending the cul- UP plots. In 1993, however, treatment tivation of rice in UP fields, because effects were not significant. The brown spot may become a limiting severity of brown spot increased factor.

Effect of submergence of rice plants on the development of sheath blight

B. Das and A. P. Dath, Central Rice Research Institute (CRRI), Cuttack, Orissa 753006, India

During the monsoon season, heavy and continuous rainfall keeps plants under water for extended periods of time. We studied the impact of submergence on sheath blight (ShB) infection in rice.

Plants of a highly susceptible rice cultivar, Annapurna, were grown in pots well supplied with fertilizer. When the plants were at flowering stage, leaf sheaths of the second youngest leaves in each of three tillers per plant were inoculated with a sterilized rice “stem” piece colonized by the causal fungus, Rhizoctonia solani Kühn.

Three days after inoculation, grayish-green lesions measuring 3.0-3.5 cm developed on the inoculated tillers. The inoculum was gently removed with sterilized forceps, and the plants were submerged to establish lesions. The plants were removed from water at intervals and placed in a glasshouse. Three replications were maintained for each treatment. On the 14th d after inoculation, lesions on each inoculated tiller was measured at the same time with leaf infection and scletoria produced.

of the infected plants greatly reduced the development of ShB (see table). Disease continued to develop in plants that were under water for 2 d, but beyond that period we observed a sudden and strong decrease in the progress of infection. Disease develop-

Results indicated that submergence

Development of ShB infection in rice plants subjected to submergence, Cuttack. India, 1996 WS.

Duration of Mean Extent Sclerotia submergence lesion of leaf produced

(cm) (d) length infection a (no.)

0 38.7 ++ 18 2 28.2 ++ 5 4 12.3 + 3 6 6.7 0 8 4.0 0

10 3.7 0 Continuous No further submergence infection Control 45.5 +++ 26 (no submergence)

CD for treatments 5% = 5.1 1% = 7.1

a - = none, + = slight, ++ = moderate, +++ = severe.

ment in 6, 8, and 10-d submergence treatments was significantly lower than in 0, 2, and 4-d treatments. Almost no

Integrated pest management—diseases

Vol. 22, No.2 39

- - -

disease developed in the continuous submergence treatment. Control treatments, in which the plants were not subjected to submergence, showed significantly highest disease with higher leaf infection and more sclerotia than all other treatments.

Prolonged submergence is not a favorable environment for rapid mycelia proliferation and infection in the host.

Effect of crop growth stage and N level on leaf blast monocyclic parameters on a new rice plant type

I. B. Pangga and P. S. Teng, IRRI; and A. D. Raymundo, UP Los Baños, College, Laguna, Philippines

We studied the effect of crop growth stage and applied N on leaf blast monocyclic parameters in two blast- susceptible cultivars, a new rice plant type line, IR64454-81-1-3-2, and with IR72 serving as the control (see table). Sporulation was converted to area under the sporulation curve (AUSC, in spores lesion - 1 d -1 ) using the equation

where X 1 = number of spores produced at ith observation, Ti = time (d) between observations, and n = total number of observations.

The first greenhouse experiment used a split-split plot randomized complete block design with three replications. Three pregerminated seeds were directly sown in each plastic pot (500 cm 3 ) of 0.5 kg soil, and the plants thinned to one plant at 7 d after sowing. Urea N (46-0-0) was applied in three equal splits. Inoculum (20 mL of Pyricu- laria grisea isolate PO6-6) at 150,000 spores mL -1 was sprayed at a height of 1.5 m inside a 0.8 × 0.8 × 1.5-m chamber on 12 plants using an atomizer at 10 psi for 30 s. Plants were inside dew cham- bers for 24 hand in a mist room for 5 d.

The second experiment used the same procedure, but 50 mL of inoculum was sprayed on six plants per sub- subplot inside a 3.5 × 3.5 × 1-m chamber placed in an air-conditioned room and leaves were sprayed with water hour- ly in daytime and covered with wet jute sacks and polyethylene sheets at night. At 12 h after inoculation, 1 cm leaf portions were cut from the top, middle, and bottom of three plants, fixed in 50% glycerin, and the number of spores counted. Leaf area was measured per plant using a Licor LI-3000 leaf area meter. Incubation period was determined by counting the lesions per plant daily starting from inoculation up to 7 d inside the mist room. Sporulation was assessed on five isolated lesions on the two upper leaves of three sample plants every morning up to 5 d of symptoms using small agar disks of known area. The number of spores produced per lesion was counted on three isolated sporulating lesions located on the two upper leaves of three sample plants at 3-d intervals starting 5 d after inoculation.

lesion area, severity, infection ratio, latent period, and AUSC (see table). Cultivar type affected all monocyclic parameters, except for the latent

Crop growth stage affected leaf blast

period. Other authors have reported nonsignificant differences in latent period among cultivars with susceptible lesion types. Nitrogen level affected lesion area, infection ratio, and AUSC. Lesion area at maximum tillering stage was significantly higher than the lesion areas at early tillering and early booting stages. Leaf blast severity and infection ratio at early tillering stage was significantly higher than the leaf blast severity at early booting stage. Latent periods at early and maximum tillering stages were significantly lower than the latent period at early booting stage. The highest AUSC was observed at early tillering stage and decreased as crop growth stage progressed (see table). Leaf blast lesion area, severity, infection ratio, incubation period, and AUSC were higher on IR72 than on the new plant type (see table). Lesion area significantly increased as N level increased from 0 to 180 kg N ha -1 . The effect of N level on leaf blast severity was not significant. Infection ratios at 90 and 180 kg N ha -1 were significantly higher than the infection ratio at 0 kg N ha-1 but not between each other. A significantly higher AUSC was observed at 180 kg N ha -1 than at 0 and 90 kg N ha -1 .

Effects of crop growth stage, cultivar, and N level on leaf blast monocyclic parameters. a

Treatment

Lesion area b Severity b.d Infection Incubation Latent AUSC c.e

(cm 2 plant -1 ) (% plant -1 ) ratio b period b period b (no. spores

(no. lesions (d) (d) lesion -1 d -1 ) plant -1 /no.

spores deposited plant -1 )

Main plot (crop growth stage) Early tillering (15 DAS) Maximum tillering (30 DAS) Early booting (45 DAS)

Subplot (cultivar) IR72 New plant type

Sub-subplot (N level) 0 kg N ha -1

90 kg N ha -1

180 kg N ha -1

0.357 b 0.99 a 1.036 a 0.27 ab 0.049 b 0.01 b

0.772 a 0.54 a 0.189 b 0.32 b

0.131 a 0.37 a 0.442 b 0.44 a 0.868 c 0.47 a

0.01248 a 6 a 0.00392 ab 5 a 0.00022 b 6 a

0.00924 a 6 a 0.00184 b 5 b

0.00368 a 5 a 0.00681 b 6 a 0.00612 b 6 a

6 a 6 a 7 b

6 a 6 a

6 a 6 a 6 a

2637 a 723 b 109 c

1440 a 873 b

718 a 976 a

1775 b

a In each factor within a column, means followed by a common letter are not significantly different by LSD at 5% level. b Incubation period = no. of days from inoculation until 50% of final no. of lesion is reached. Severity (%) = lesion area divided by the leaf area multiplied by 100. Latent period = no. of days from inoculation until 50% of the lesions start sporulating. Means of two trials with three replications. c Means of three replications. d Severity at 1 wk after inoculation. e AUSC = area under the sporulation curve.

40 IRRN 1997

Variation in isolates of Sclero- tium oryzae, the rice stem rot pathogen

Z. Ali, Mycology and Plant Pathology Laboratory, School of Botany, The University of Melbourne, Parkville, Victoria 3052, Australia

Sclerotium oryzae (conidial state, Helminthosporium sigmoideum Cav., and ascigerous state, Magnaporthe salvinii

Krause and Webster) is the causal agent of stem rot of rice. It causes significant yield losses in India and neighboring countries. The pathogen varies in morphological and cultural behavior even among the isolates collected from the same geographic area. We studied the variability of five isolates collected from Bangladesh (SO-B), India (SO-I), Nepal (SO-N), Pakistan (SO-P), and Sri

Lanka (SO-S) to document cultural, sclerotial, and other characters.

The isolates varied in colony and sclerotial characters. Appressoria varied mainly in size and number of lobes appressorium -1 . Sclerotia viability was highest in isolate SO-N at 30°C and at room temperature but maximum viability in isolate SO-I occurred at the surface of the soil (see table).

Susceptibility to insecticides of brown planthopper Nilaparvata lugens in the lower Yangtze Valley

Wang Yinchang and Li Guoqing, Institute of Agricultural Entomology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; Deng Xihua and Din Shiyin, Agricultural Research Institute, Anqing Region, Anhui, China; and Su Jiankun, Agricultural Research Institute, Li Xie He Region, Jiangsu, China

Adult brown planthopper (BPH), more than 50 females of each population, have been collected from ricefields of Anqing (Anhui Province) and Yang- zhou (Jiangsu Province) and multiplied with rice in the laboratory at 25°C, 16 h photoperiod since 1989. Assays were conducted using female adults of F 2 -F 3 within 5 d after emergence by the

topical treatment method. Technical grade insecticides were dissolved in analytical grade acetone and five or more diluted concentrations were prepared. For each concentration, 50 macropterous females were treated with 0.05 µL of solution applied by microsyringe on the thoracic dorsum. Monitoring was done 48 h after treatment. Dose-mortality regressions were estimated by probit analysis. LD 50 s were considered to be indicative of resistance and their differences among years were tested by t test. The formula used was

where m 1 = log LD 50 and s 2 m 1 or s 2

m 2 is the variance of m 1 or m 2 , respectively. If t is >1.96 or <–1.96, there is significant difference between m 1 and m 2 .

The results are shown in the table. Although LD 50 s fluctuated among years, resistance ratios varied little when compared with those in 1995. The reduction of the dosage of conventional insecticides applied to BPH in recent years has resulted from the wide application of buprofezin and of rice varieties resistant to BPH.

Review of notes. The IRRN editor will send an acknowledgment card or an e-mail message when a note is received. An IRRI scientist, selected by the editor, reviews each note. Reviewer names are not disclosed. Depending on the reviewer's report, a note will be accepted for publication, rejected, or returned to the author(s) for revision. Comments. If you have comments or suggestions about the IRRN, please write to the editor.

Vol. 22, No.2 41

Comparison of different S. oryzae isolates.

Character SO-B

Average colony diameter in mm (5th day) 64.33

Color of colony White Time taken for sclerotial initiation (h) 144 Color of sclerotia Shiny black Sclerotial pattern Scattered round Size of sclerotia (µm) 296.5 Color of appressorium Light brown Size of appressorium

Length (mm) 11-27 Width (mm) 9-27

Number of lobes appressorium -1 10 Viability of sclerotia at

30°C (mo) 16 room temperature (mo) 19 soil surface (mo) 9

SO-I

63.00 Cottony white 120 Black Scattered round 247.3 Brown

12-29 9-25 9

17 20 11

SO-N

74.66 White 120 Black Embedded in mycelium 255.3 Brown

14-30 z8-26 9

19 24 10

SO-P

56.66 White 96 Brownish black Scattered round 214.9 Brown

14-26 11-24 11

16 17 8

SO-S

62.33 White 124 Black Scattered round 224.9 Brown

12-27 9-22

10

17 18 9

Integrated pest management—insects

Variation in susceptibility of BPH to insecticides. China, 1991-95.

Insecticide Parameters a

1991 1992

LD 50 (µg head -1 ) 0.12 0.09 value 6.28 3.65

Slope 1.49 1.87 t value** -3.81 -2.59

DDVP LD 50 (µg head -1 ) 0.05 0.04 value 1.97 0.42

Slope 1.45 1.51 t value 3.29 3.75

Monocrotophos LD 50 (µg head -1 ) 0.02 0.01 value 1.38 0.11

Slope 1.49 1.45 t value 0.44 0.94

Methyl parathion LD 50 (µg head -1 ) 0.10 0.05 value 3.56 1.13

Slope 1.93 1.49 t value -3.65 1.62

Parathion LD 5 0 ((g head -1 ) 0.21 0.11 value 1.65 0.40

Slope 1.32 1.35 t value -3.51 1.4

Fenitrothion LD 50 (µg head -1 ) 0.11 0.06 value 1.47 1.29

Slope 1.18 1.42 t value -3.59 0.18

Methamidophos LD 50 (µg head -1 ) 0.04 0.05 value 5.81 2.40

Slope 1.53 1.92 t value 4.22 2.51

lsoprocarb LD 50 (µg head -1 ) 0.05 0.04 value 0.78 2.38

Slope 1.28 1.45 t value -1.79 -0.50

Carbaryl LD 50 (µg head -1 ) 0.04 0.03 value 3.57 1.88

Slope 1.38 1.47 t value -2.33 0.96

DMPC b LD 50 (µg head -1 ) 0.11 0.04 value 2.74 2.78

Slope 1.93 1.57 t value -6.14 1.15

Carbofuran LD 50 (µg head -1 ) 0.01 value 5.02

Slope 1.10 t value -1.99

Fenvalerate LD 50 (µg head -1 ) 0.14 0.06 value 0.71 0.38

Slope 1.25 1.26 t value -4.23 1.46

Deltamethrin LD 50 (µg head -1 ) 0.10 0.04 value 1.95 0.40

Slope 1.12 1.17 t value -4.23 1.46

Buprofezin LD 50 (µg head -1 ) 0.02 value 0.72

Slope 1.08 t value -7.72

--666

Anqing

1993

0.07

1.56 0.38

-0.88

0.04 2.06

4.09

0.02 0.20 1.40 0.02

0.06 0.47 1.50 0.39

0.15 1.15 1.36

1.80

-0.82

0.07 0.33 1.36

-0.44

0.05

1.71 1.84

1.83

0.05 2.46 1.50

-1.54

0.04 1.30 1.59

-1.36

0.05 0.62 1.67 0.58

0.01 2.14 1.72

-0.36

0.06 0.23 1.36 1.16

0.05 0.62 1.35 1.16

0.01 1.30 1.47

-8.08

Yangzhou

1994 1995 1992 1994 1995

0.07

1.46 5.78

0.05 0.07 0.00 0.00 0.84 6.90 3.18 4.63

0.00

1.23 2.87 2.32 2.19 1.58 1.48 2.30 -3.27 1.23

0.02 0.02 0.00 0.00 0.09

0.00 0.29 3.59 2.21

1.50 1.50 2.36 2.07 1.66 0.07

0.30 3.32 1.25

0.05 0.06 0.08 1.01

0.04 0.76 6.13

0.05 2.24

1.23 1.88 2.07 1.86 2.01 -4.50 0.70

0.15 0.13 1.26 2.26 1.53 1.56

5.68 1.58

-1.13

0.06 0.06 1.58 0.24 1.38 1.13 0.41

0.06 0.06 0.01 0.00 0.54

0.01

1.69 1.52 2.90 2.15 0.71

2.11

0.05 0.04 0.01 0.01 0.01 2.47 3.77 0.96 1.13 1.19 1.46 1.50 2.78 2.34 1.99

0.81 1.32 3.49 0.66

0.88 1.34

-1.46 -2.84 -3.28

0.03 0.03 0.01 0.01 6.76

0.01 0.87 6.17 5.00

1.62 5.48

1.50 2.37 2.40 0.03

2.20

0.05 0.05 0.01 0.01 0.02

2.85 0.74

0.98 0.37 2.12 1.38 0.15 1.68 1.49 1.78 2.10 2.39 0.72 2.68 1.60

0.02 0.01 1.72 0.01 1.82 1.79

-0.83

5.78 1.48 0.07 0.08

1.36 1.29 0.23

0.05 0.05 1.65 1.10 1.00 1.34 0.23

0.02 0.00 0.80 0.06 1.82 1.13

-7.75

a LD 50 s of - 666 in other years compared with 1994 data. LD 5 0 s of other insecticides compared with 1995 data. b A native Insecticidal mixture, mainly composed of 3,5-dimethylphenylcarbamate and 3,4-dimethylphenylcarbamate.

42 IRRN 1997

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Effect of rice armyworm Mythimna separata (Walker) on grain yield of rice

G. C. Santiago, E. G. Rubia, V. P. Gapud, H. D. Justo, and S. R. Obien, Crop Protection Division, Philippine Rice Research Institute (PHILRICE), Muñoz, Nueva Ecija, Philippines

A survey conducted in Maligaya, Nueva Ecija, Philippines, showed that farmers (n=100) consider the armyworm (AW) Mythimna separata (Walker) one of the most important insect pests of rice during the dry season. The AW hosts include sugar-cane, sorghum, maize, bamboo, and some grasses. At night, AW larvae are actively feeding and cutting rice panicle rachis and stems (see figure). During the day, they are found at the base of tillers.

The occurrence of AW forces some farmers to harvest earlier than sched- uled for fear that panicles will be lost. This study quantified the effect of AW on grain yield by comparing healthy hills with hills affected by AW. This information may be used to estimate yield reduction caused by AW.

We studied a 1000-m 2 farmer's field planted to cultivar IR64 at the rate of 3-4 seedlings hill -1 . Fertilizer was applied

Predation of Chilo suppressalis (Walker) eggs by the black cricket Metioche vittaticollis (Stål)

H. Lee, National Honam Agricultural Experiment Institute, Rural Development Administration, Korea; and M. L. P. Almazan and K. L. Heong, IRRI

Metioche vittaticollis (Stå1) is an important predator of rice insect pests, including several defoliators and stem borers. Little information is available about its role in suppressing pest populations.

We studied the predation of M. vittaticollis using striped stem borer (SSB) eggs as prey in insect cages. Freshly laid egg masses of SSB were glued to leaves of 35-d-old TN1 rice

Armyworm pupa at the base of tillers and spikelets scattered on the ground as a result of pAW larval feeding. 1996 dry season.

at the rate of 90-30-30 kg NPK ha -1 . One week before harvest, 10 plots attacked by AW (at least one panicle lost) and 10 healthy plots measuring 2 × 2 hills plot -1

were marked using 1-m-long bamboo stakes. Two days before harvest, each

plot was harvested to quantify grain yield, total spikelets panicle -1 , panicles

of filled grains.

panicles clipped by AW. Grain yield of healthy plots differed significantly from that of plots attacked by AW (see table). Reduction in grain yield was less than the percentage of panicles lost due to AW. The AW significantly decreased the number of panicles hill -1

and the number of spikelets panicle -1

but did not affect 100-grain weight or percentage of filled grains.

Further studies should be made to

crop-AW system, to determine the extent of AW damage and its economic

plot -1 , 100-grain weight, and percentage

Results showed about 20% of the

identify the factors influencing the

loss, and to develop means of man- aging the pest.

Grain yield and yield components of plots attacked by armyworm (AW). Maligaya, Muñoz, Nueva Ecija, Philippines, 1996 DS.

Grain yield or yield component Healthy hills Hills attacked by AW Prob > ITI

Grain weight (g m -2 ) 458 ± 7.4 379 ± 19.2 0.0012** Total spikelets (no. panicle -1 ) 90.6 ± 1.3 69.4 ± 4.6 0.0003** 100-grain weight (g) 2.55 ± 0.04 2.48 ± 0.03 0.175ns Total panicles (no. m -2 ) 388 ± 19.9 309 ± 19.4 0.0115ns Filled grains (%) 78.2 ± 1.9 75.0 ± 2.3 0.2340ns

plants at densities of 80, 160, 240, 320, and 400 plant -1 . These plants were enclosed individually in 11-cm-diam and 55-cm-high cylindrical mylar cages. One M. vittaticollis, starved for 12 h, was released for each test plant. Fourth-instar larvae and adult male and female crickets were caged individually with the eggs, and the experiment was replicated 10 times. After 24 h of exposure, the number of eggs consumed at each stage was recorded. Consumption rate per day at each stage of M. vittaticollis was determined.

Fourth-instar larvae consumed the highest number of SSB eggs as compared with the other stages of the cricket (Table 1). They fed more than the first three instars combined, probably because of the higher nutri-

tional demands at this late growth stage for developing the reproductive system and flying appendages. Fe- males were more voracious than males. The higher predation rates by the female predator could be attributed to physiological needs for reproduction.

The density response data were fitted to the random predator model

Na = n[1-exp{-a(PT-NaTh)}] where Na is the number of prey attacked, N is the density of prey, a is the attack rate of the predators, P is the number of predators, Th is handling time, and T is the total time that predator and prey are exposed.

The search parameters, a and Th, were estimated using the nonlinear curve-fitting procedure PROC NLIN available in SAS (Table 2). In the males,

Vol. 22, No. 2 43

Table 1. Number of C. suppressalis eggs consumed Th was significantly higher, indicating by M. vittaticollis for 1 d at a temperature range of 25-30 °C. that they have lower feeding capacities

Consumed C. suppressalis The figure illustrates the relation- eggs (no. d -1 )

Mean ± SD a Range attacked and initial egg density. The

than females.

Stage ship between number of SSB eggs

Nymph 1 st instar 1.7 ± 0.67 2 nd instar 2.5 ± 0.71 3 rd instar 13.3 ± 5.58 4 th instar 184.3 ± 45.2

Male 102.7 ± 23.23 Female 158.7 ± 53.56

Adult

a Av of 10 individuals ± SD.

number of SB eggs attacked by one

1-3 fourth-instar larva, an adult male, and 2-4 an adult female increased with prey

8-24 density. As initial density increased, 162-246 the consumption of SSB eggs by the 72-147 cricket increased at a decreasing rate 78-246

Table 2. Parameter estimates of the functional response equation for M. vittaticollis feeding on C. suppressalis eggs at a temperature range of 25-30 °C.

Parameter estimates a Asymptotic SE Stage

a Th a Th

4 th -instar nymph 9.9381 0.0037 30.5532 0.0011 Adult male 4.5044 0.0070 4.6008 0.0009 Adult female 4.7314 0.0044 5.3486 0.0009

a a = attack rate, Th = handling time.

until a satiation level was reached. The functional response of fourth-instar larva, adult male, and adult female on SSB eggs fitted the Holling's Type II model. This model has also been found to fit the feeding behavior of Cyrto- rhinus lividipennis on planthopper eggs and Pardosa pseudoannulata on brown planthoppers and green leafhoppers.

Functional response of M. vittaticollis on SSB eggs.

Bioassay of Fusarium pallido- Mortality was determined after 1 wk of showed that 5.49 × 10 3 conidia mL -1 was

mycotina: Hyphomycetes) roseum (Cooke) Sacc., (Deutero- incubation and the percentage adjusted the effective concentration for LD 50 of

using Abbott's formula. Probit analysis F. pallidoroseum (see table).

against leaffolder Mortality dose of F. pallidoroseum on rice leaffolder larvae.

Larvae used (no.) S. Manisegarane, S. Letchoumanane, A. Mohamed Hanifa, M. Subramanian, and N. 180 9.456 0.622 5.49 × 10 3 2.49 – 12.11 × 10 3

2a Slope LD 50 (conidia mL -1 ) Fiducial limit

Ramadoss, Pandit Jawaharlal Nehru College of Agriculture, Nedungadu, Karaikal 609603,

a P < 0.05. Heterogeneity analysis: variance = 0.0246. Results of c 2 for the above analysis = 13.86719.

Pondicherry, India ~~

Greenhouse studies assessed the patho- genicity of Fusarium pallidoroseurn-on rice leaffolder (LF) Cnaphalocrosis medi- nalis Guenée at 28.5 °C and between 88 and 90% relative humidity. The pathogen was tested at spore concentrations of 0-1×10 7 conidia mL -1 . A stock solution of 1 mL was diluted with sterile distilled water, i.e., 100, 1000, etc., which meant 1 part of the fungus suspension was diluted in 99 or 999 parts of water. Thirty third-instar larvae were dipped for 2 to 3 s in each concentration. Treated larvae were transferred to filter paper and incubated in a petri dish containing fresh rice leaves.

Evolving patterns of rat control at IRRI

M. A. Bell, E. Nunn, G. Pateña, E. Nuevo, V. Fernando, and K. L. Heong, IRRI

This report discusses the changes made at IRRI that have reduced rat problems. A 1987 survey (by N. S. Ahmed and others) indicated that 86% of some 171 field experiments, including 11 trials that were completely lost, suffered rat damage. The lost data were valued at US$370,000 and the direct cost of con-

trol US$402,000 (see figure). In 1989, control costs had risen to US$473,000 but by 1994, they had dropped to US$52,000, an annual savings of US$421,000 and lost data costs were also decreased.

galvanized iron fences with a single electrified wire at the top. The system had 24-h surveillance by 160 persons involved in rat control. Starting in 1989, an integrated system of rat control, combining six management practices, has led to the dramatic reductions in

Early rat control at IRRI consisted of

44 IRRN 1997

Integrated pest management—other pests

c

Table 2. Rate of fertilizer applied to the sandy or black soil types of Svay Rieng District.

Fertilizer type Farmers applying fertilizer (no.) Av rate (kg ha 1 )

Sandy soil Black soil Sandy soil Black soil

DAP or 16:20:0 20 19 39.7 (± 21.2) 48.2 (± 24.3) Urea FYM

7 8 16.3 (± 7.2) 18.3 (± 13.6) 3 3

Table 1. General information on the households surveyed in Svay Rieng District.

Total sample 25 Av farm size 1.6 ha (± 0.7) Av family size 6.7 persons (± 2.1) Av area of farms with

only sandy soil only black soil 1.50 ha - 3 farmers sandy and black soil 1.75 ha (1.0 black; 0.75 ha

0.95 ha - 4 farmers

sandy) - 18 farmers

We surveyed 25 farmers in 3 com- munes and 9 villages in the Svay Rieng District, 100 km southeast of Phnom Penh, during July 1994. Annual rainfall is about 1300 mm, mainly between May and October, with rice transplanted in July-August and harvested in Decem- ber-January. The area contains "black" Alumisol (plinthaquult) and "sandy" cultural hydromorph (plinthustalf) soil types. Typical analysis of the sandy and

I. Dubus and H. Richard, Institut national agronomique Paris-Grignon, Agronomy and Environment Department, 16 rue Claude Bernard, 75005, Paris, France; P. F. White and M. Bolton, Cambodia-IRRI-Australia Project, P.O. Box 01, Phnom Penh, Cambodia

Fertilizer management on two contrasting soil types in the rainfed lowland rice production system in Cambodia

the costs of rat control and damage. The system includes 1) the installation of underground pipes to replace open drainage canals (this removed kilo- meters of difficult-to-manage rat habitats), 2) the implementation of a closed season twice a year to limit food supply and breeding of rats, 3) periodic bund reconstruction to destroy habitats, 4) baiting stations around farm peri- meter in fields and along bunds, 5) weekly flame throwing (primarily in active burrows), and 6) the use of an active barrier system (ABS). The ABS was developed by Y. M. Lam in Malay- sia and modified slightly by G. Quick and others for IRRI conditions. It

consists of low plastic fences rather than metal fences. Both systems have live traps behind holes spaced around the barrier. The 24-h surveillance and electric fence system are no longer used.

Changes in rat control practices have permitted mechanization of many farm

Rat control expenditures. IRRI, 1985-94.

operations. Covering drainage canals and the removal of fixed fences allow large machinery to enter fields easily, resulting in other cost reductions.

research station differs from that of farmers. Researchers are typically dealing with crops that are worth more than the cost of the lost grain. For example, a breeding line or experimental plot may represent several years of work, information, and researcher time and effort. Nevertheless, the systems used at IRRI have general application and highlight the importance of general hygiene and sustained effort.

The importance of rat control at a

black soils are, respectively: pH (water), fertilizer types and applied them as 5.9,5.1; organic C (%), 0.29,1.09; total N MAP (16%) N, 20% P 2 O 5 ) or DAP (16%) N, (%), 0.03, 0.11; CEC (meq 100 g-1 soil), 46% P 2 O 5 ), depending on availability. 1.3, 6.7; Olsen P (ppm), 0.4, 2.6; clay (%), Urea was managed differently from the 6, 27; silt (%), 55,38; and sand (%), 38, 35. compound fertilizer. Use of farmyard

More than two-thirds of the sur- manure (FYM) was closely linked to veyed farms had both soil types but transportation; hence, sandy soils near generally more black than sandy the village received most of the manure. (Table 1). The black soils, located in the The hardness of the soils caused diffi- lower parts of the toposequence and culties in plowing and required different farther from the village than the sandy transplanting strategies. Water availabi-

All but two farmers regarded the black between the two soil types. Crops soil as superior to the sandy soil when mature unevenly and 4-5 d earlier on the fertilizer was applied. About 35% of sandy soil than on the black soil. the farmers, however, regarded the Farmers clearly distinguished between sandy soil as superior to the black soil the two types of soil and had a sophisti- when no fertilizer was applied. On cated understanding of their respective average, farmers applied more management requirements. The black fertilizer to black soil than to sandy soil soil, although referred to by farmers as (Table 2). Cost, availability, and ease of homogeneous, ranged from better to transport were major factors affecting poorer than sandy soil. These factors the rate of fertilizer application. must be considered when formulating

soils, had a more reliable water supply. lity to the plant also seemed to vary

Farmers did not discriminate between soil classes for extension and research.

Farming systems

- -

Vol. 22, No. 2 45

Establishment of wheat following lowland rice in east India

R. B. Thakur, Agronomy Department, Rajendra Agricultural University, Pusa, Samastipur, Bihar 848125, India

A field experiment was conducted on the economic feasibility of relay wheat cropping in the lowland rice ecosystem at Pusa (Bihar) during 1993-94 and 1994-95. It used a split-plot design with three replications and six methods of wheat crop establishment in the main plot and three seed rates in the subplot. The soil was silty clay, pH 8.4 (1:2.5, soil:water), with initial nutrient status of 262 kg N ha -1 , 34.5 kg P ha -1 , and 110 kg K ha -1 . A long-duration traditional aman rice variety, Sudha, was transplanted under normal practices in both the years and the wheat variety Sonali was grown according to treatments listed in the table. In relay cropping, wheat seeds were broadcast 10-12 d before harvest in standing rice to avoid delayed seeding. Three seed rates, i.e., 125, 150, and 175 kg ha -1 were with all subplot treatments. Wheat crops were also raised by normal practices, except for relay and zero tillage. In relay cropping, fertilizer was used after the first irrigation.

In wheat cultivated in the lowlands, Chenopodium album, followed by Launia pinnatifide, is the dominant weed where

wheat is tilled. In relay cultivation, L. pinnatifide is the dominant weed in early growth and later Cyperus rotundus and Cynodon dactylon become dominant. More or less the same trend is observed in all plots where preparatory tillage is not done.

The maximum grain equivalent yield (see table) was recorded under T6, which was superior to all treatments except T5. Relay practice and paraquat

application with different sets of minimum tillage (Tl, T2, and T3) were statistically alike and ranked second. Therefore, sowing wheat in well-prepared field is advisable. If land is not ready for plowing, relay or minimum tillage are also advisable. The same trend was observed for economic return. A 150 kg ha -1 seed rate was profitable irrespective of crop establishment methods.

Effect of wheat crop establishment method and seed rate treatment on yield and economic return in a lowland rice ecosystem. Bihar, India, 1993-95.

Yield in terms of Economic Benefit- wheat equivalent return cost

Treatment (t ha -1 ) (US$ ha -1 ) ratio

Grain Straw Gross Net

Method of wheat crop establishment

crop on 25 Nov)

after rice harvest and sowing at 24 h after that by hand plowing on 6 Dec

T3 Paraquat application, rototilling (once) and sowing behind the hand plow on 10 Dec

T4 Rototilling twice and sowing behind the 4.2 5.5 554 277 2.00 hand plow on 10 Dec

T5 M.B. plow (once) + rototilling (once) and 4.6 6.2 617 335 2.18 sowing behind the hand plow on 12 Dec

T6 M.B. plow (once) + rototilling twice and 4.8 6.4 635 346 2.20 sowing behind the hand plow on 12 Dec LSD (0.05) 0.2 0.3 26 14 0.15

5.6 561 292 2.09

T1 Relay cropping (sowing in standing rice 4.3 5.4 572 307 2.15

T2 Paraquat application @ 2.0 kg ha -1 just 4.5 5.5 592 321 2.18

4.3 5.7 574 302 2.11

Seed rate (kg ha-1) S1 - 125 4.2 S2 - 150 4.5 6.1 600 328 2.20 S3 - 175 4.7 6.3 628 351 2.10

LSD (0.05) 0.2 0.3 29 18 0.10

Stripper harvesting improvements meet Chinese needs

Zhang Bao Zhao, Agricultural Engineering Department, China National Rice Research Institute (CNRRI), Hangzhou, China

Stripping grain, as a method of harvesting rice, was introduced into this Hangzhou institute in 1994 when we first tested the IRRI-designed SG800 system. This system represents the Stripper-reaper system for rice harvesting.

Postharvest technology

46 IRRN 1997

simplest form of stripper harvesting with low intake of nongrain material in standing rice and acceptable levels of grain loss. The bulk of the straw standing in the field after stripping is un- acceptable in most Chinese multi- cropping systems because it is neces- sary to remove the straw from the field to allow quick land preparation (1-2 d) between the first rice harvesting and second rice replanting (1-2 d).

Our work during the past 2 yr has proceeded along two lines to meet Chinese rice farmer needs. A stripper rotor placed before a reaper front (stripper-reaper system) has been fitted on a hand tractor (see figure). The appropriate distance between rotor and cutter bar is selected so the straw, after being stripped, can be cut in standing

Test results of stripper-reaper and strippercombine systems.

Item SR-1000 SC-1300 system system

Power (kW) 8.8 11.0 Cutting width (mm) 1000 1300 Forward speed (km h -1 ) 2.8-3.6 3.0-3.5 Feed rate (kg s -1 ) 1.1 1.3-1.4 Nongrain material (%) 12.3-17.3 3.5-4.5 Grain damage (%) 0.085 0.31 Total losses (%) 0.49-0.90 2.5-3.0 Total weight (kg) 850 1200 Estimated costs (US$) 600 1800 Labor demand (labor-days ha -1 ) 4-5 2-3

position and windrowed to the side. (The stripped material feeds from stripper rotor into the tank above the reaper- front.) The engine is moved to the rear to center-balance the weight of the harvesting components. The adjus-

table skid under the engine enables the rotor to be raised or lowered, depending on crop height. Tests show that this machine has the field capacity of 1.3 ha d -1 for grain harvesting and straw windrowing with grain losses less than 0.9% (see table). Estimated cost of the machine (excluding tractor) is acceptable. The wage rate of mechanical operation will be half that of the manual operation.

conveyor on the front of a self-pro- pelled crawler track chassis with a re- thresher and cleaner on board. The design is less labor-intensive, and is highly maneuverable in most of the wet fields in southern China. Preliminary test results of the stripper-combine system are also listed in the table.

In 1996, we fitted a stripper rotor and

Research methodology A rapid method of isolation of genomic DNA from filamentous fungi

P. Kachroo and S. A. Leong, Plant Pathology Department and USDA-ARS Plant Disease Resistance Unit, University of Wisconsin, Madison, WI 53706, USA; and B.B. Chattoo, Microbiology and Biotechnology Department, Faculty of Science, The Maharaja Savajirao University of Baroda, Baroda 390002, India

This method uses fungus cultured on potato dextrose agar at 28 ºC. When mat growth was visible on at least half of the plate (2-3 d), a 0.5 × 0.5 cm mycelial piece was removed with a surgical blade and placed in a 1.5-mL microfuge tube. The block was suspended in 600 µL of buffer (Tris 100 mM, pH 8.0, EDTA 150 mM, pH 8.0; NaCl 100 mM; SDS 2%; phenol 50%), and 200-300 mg of glass beads added, the contents vortexed for 3 min, and centrifuged at 13 K for 10 min. The supernatant was treated with RNase A (10-15 µg) for 15 min at 37 ºC, extracted with phenol: chloroform: isoamyl alcohol (25:24:1), and the DNA precipitated with 2

volumes of absolute alcohol at room temperature. The DNA was washed with 70% alcohol and suspended in 30 µL of TE (Tris 10 mM; pH 8.0; EDTA 1 mM, pH 8.0). Genomic DNA appeared as a single, high-molecular-weight band when analyzed by a 0.8% agarose gel run in 0.5 × TBE. To evaluate DNA prepared by this

(PCR) and random amplified chain, five monoconidial isolates of the rice blast fungus Magnaporthe grisea were analyzed. The primers used for PCR were based on the sequence of a trans- posable element Pot2 and the flanking target site. Two monoconidial preparations of the isolate B157 were included. The PCR was carried out in a 50-µL reaction volume of 10 mM Tris, pH 8.3; 50 mM KCl; 2.5 mM MgCl 2 ; 100 µM each of dATP, dCTP, dTTP, dGTP; 20 pM of each primer (17 mer); 2.5 units of Taq DNA polymerase (Perkin-Elmer); and 0.1 µg of template DNA. The thermal cycler was programmed for 94°C, 2 min denaturation followed by 35 cycles of 94 °C 1 min; 45 °C 1 min; and 72°C 2.05 min. The final extension

method for polymerase chain reaction

Polymerase chain reaction (PCR) amplification of a part of 5'-region of Pot2, an inverted repeat transposon, using the genomic DNA of two isolates of Magnaporte grisea as a template. The expected size of amplification is 0.9 kb as seen in the figure. Lanes 1 and 2 represent isolates Co1043 and B101, respectively. Lanes 2 and 3 correspond to the PCR product amplified from the DNA obtained from two separate monoconidias of isolate B101. Lanes 4 and 5 also represent isolate B101, but the DNA template used in the PCR reaction was prepared using a standard method. The last lane corresponds to the kb ladder (BRL, USA) used as a molecular weight marker.

Vol. 22, No. 2 47

48 IRRN 1997

calcium hypochlorite, and infected tissues are cut into small sections and placed on petri dishes with potato dextrose agar (PDA) with 1 ml L 25% lactic acid. After 2 d, R. solani colonies are again plated on PDA. Three 8-mm leaf cuts obtained from third or fourth leaves of 40- to 50-d-old IR72 are placed on water agar (0.5 g

-1

lasted 5 min at 72 °C. The PCR products were visualized on a 1 % agarose gel run in 0.5 × TBE buffer and stained with ethidium bromide. The figure reveals amplifications of the expected size and they were identical to the DNA isolated using a standard method. DNA preparations from both the monoconidial isolates of B157 amplified the desired product, indicating reproducibility.

The yield of DNA using this method was 0.5-1.0 µg from a small sample of mycelia, which is sufficient to carry out a number of PCR and randomly amplified polymorphic DNA reactions. Employing this method of DNA extrac- tion, we have been able to extract DNA of good quality from other filamentous fungi ( Aspergillus, Fusarium, Phytium, Rhizoctonia, and Sclerotirzia ) that confirm its general applicability.

Method for detecting rice sheath blight pathogen in soil samples using mungbean

N. P. Castilla, F A. Elazegui, and W. M. Lanip, IRRI; S. Savary, Institut francais de recherche scientifique pour le développement en cooperation-IRRI

This technique uses mungbean ( Vigna radiata (L.) Wilczek) as a bait plant to detect propagules of Rhizoctonia solani Kiihn, a soilborne fungus that causes rice sheath blight. The technique in- volves the collection of soil samples from the field, with each sample con- sisting of 300-350 g (Fig. 1). Each sample is placed in pots (11 cm diam × 16 cm height) with holes for draining, and each pot filled with soil is placed inside a clean plastic bag to avoid contamination among samples during transport. Soil samples are air-dried for 10 d at 30-33 °C. Extreme temperatures, above 37-40 °C, which cause destruc- tion of soil organisms, must be avoided. After drying to a soil moisture content of about 17-21% (w/w), each sampleis then pounded to a particle size of approximately 2-5 mm in diameter and

1. Methodology for detecting R. solani pathogenic to rice in soil samples using mungbean seedlings.

dispensed in the original pots. Mung- bean observations are done at 2- to 3-d intervals for 15 d, starting 4 d after sowing, of number of healthy plants, -1 of diseased plants, and ungerminated seeds in each pot. Seedlings infected with R. solani have dark brown lesions on the hypocotyl and/or cotyledons. A seedling is considered emerged when its cotyledon appears above the soil agar L distilled water). About 8 mm of surface. Stems of infected seedlings that a 4- to 5-d-old mycelial plug is placed are more than 7 d old have dark brown on the center of each leaf section and lesions near the soil surface. Infected incubated at 25-27 °C for 4 d to detect mungbean are soaked for 15 s in 5% lesions.

2. Proportion of true positive and false positive samples using the presence of infected seedlings as criterion (a) and the proportion of false negative and true negative samples using two successive criteria: presence of infected seedlings and presence of R. solani- like colonies on ungerminated seeds (b).

Figure 2 shows the proportion of false positives and false negatives from a large series of samples. Criterion is based on the isolation of R. solani -like colonies on ungerminated seeds. There were 37.5% false negatives using the first criterion (presence of infected seedlings), while the proportion of false negatives was reduced to 16.0% using the second criterion in sequence (presence of R. solani -like fungus colonizing ungerminated seeds.

When the second criterion alone is considered, low contamination of a soil sample leads to very few false positives (1 and 3, respectively, for IRRI and Pila soils). However, this test leads to relatively high false negative cases (28 and 16, respectively, for IRRI and Pila soils). Nevertheless, c 2 values (19.7 for IRRI and 28.7 for Pila) indicate that this test adequately detects colonization of soil samples by R. solani.

DNA fingerprinting of bacterial blight pathogen directly from infected leaves

L. C. George, I. Oña, M. Villamayor, C. Vera Cruz, T. W. Mew, and R. J. Nelson, IRRI

In this study, we shortened the time required to obtain DNA fingerprints by using pathogen DNA prepared directly from cells leached from infected leaves. Leaves of IR24 plants grown in the greenhouse were inoculated (clip method) with six isolates of Xantho- monas oryzae pv. oryzae belonging to different lineages, and infected leaves were collected 14 d later. To ‘ooze’ bacteria from the leaves, 2-cm-long leaf fragments containing the advancing tip of lesions were cut crosswise into 10 small pieces with flame-sterilized scissors, and then soaked in 400 µL of sterile distilled water for at least 1 h. The leaf pieces were discarded and the cells concentrated by spinning the suspension for 2 min in a microcentri- fuge. Most of the water was discarded, leaving about 25 µL, in which the cells were resuspended. The cells were lysed in 200 µL of 70% ethanol (final concentration) and then spun for 10 s to pellet the cell debris. The supernatant was transferred to a new tube and spun for 5 min to precipitate DNA. The DNA was air-dried, dissolved in 10 µL of sterile water and 5 µL served as template for polymerase chain reaction (PCR). To check the consistency of the fingerprint patterns, purified DNA from the isolates used for inoculation served as positive controls. Standard PCR protocols were followed using JEL1 /JEL2 primers and with the repPCR primers BOX, ERIC, and REP using DNA from bacterial exudates from lesions and using DNA from cultured cells.

Figure 1 compares the fingerprint patterns from the alcohol lysis method to those obtained using DNA prepared by the potassium acetate method. The latter has a smeary background that obscured some bands, apparently from residual chemical contaminants. When intact cells were used directly in the PCR reaction, the results were incon-

Vol. 22, No. 2 49

1. Comparison of fingerprints obtained using DNA from Xanthomonas oryzae pv. oryzae PX0112 prepared from cultured cells by the potassium acetate method (lanes 1 and 2) and from cells leached from infected leaves by the alcohol lysis method (lanes 3, 4, 5 and 6). Infected leaves were those of IR24 grown in the greenhouse, and the primers JEL1/JEL2 were used to generate the fingerprints.

sistent. Amplification appeared more efficient when DNA was released by lysis with alcohol, and cellular debris and other contaminants were removed prior to amplification.

To assess the general utility of the method, bacteria were also leached

2. Fingerprint patterns obtained from naturally infected leaves of IR24 (lanes 1, 8, 9, and 10) and near-isogenic lines IRBB4 (lanes 2, 3, 11, and 12), IRBB7 (lanes 4, 5, 13, and 14), and IRBB10 (lanes 6, 7, 15, and 16) grown in two hot spots for bacterial blight disease in the Philippines. The molecular markers (M) consist of a 1-kb ladder. The primers JEL1/JEL2 were used in the PCR method.

from naturally infected leaf samples of IR24 and near-isogenic lines (IRBB4, IRBB7, and IRBB10) planted in Calauan and Mabitac, two hot spots for bacterial blight disease in Laguna, Philippines. Different fingerprint patterns were detected from previously frozen, infected leaf samples analyzed by TCR using JEL1/ JEL2 primers (Fig. 2). Since this method needs neither isolation nor cultivation of the pathogen, PCR of DNA from lesion exudates substan- tially reduces the time and resources required to fingerprint the bacterial blight pathogen, making it possible to conduct large-scale population studies in a cost-effective manner.

Mailing address. Send notes and correspondence to the IRRN Editor, IRRI, P.O. Box 933, Manila 1099, Philippines. Fax: (63-2) 845-0606; E-mail: [email protected]; Home page: http://www.cgiar.org/irri; Riceweb: http://www.riceweb.org; Riceworld: http://www.riceworld.org

A method for estimating the number of eggs in egg masses of yellow stem borer

A. M. Romena, IRRI; F. L. Gould, Department of Entomology, North Carolina State University, USA; and M. B. Cohen, IRRI

Egg masses of yellow stem borer (YSB), Scirpophaga incertulas (Walker), are multilayered and densely covered with hair. Consequently, it is not possible to count the number of eggs in an egg mass, either before or after the eggs have hatched. This results in difficulties in many studies of YSB behavior and host plant resistance in which plants or plots are artificially infested with egg masses, and where interpretation of results would be more powerful if the number of larvae hatching from the egg mass was known. This study demon- strates the accuracy of a method of egg number estimation that we have developed, based on comparison of test egg masses with a “reference collection.”

Our reference collection consists of 50 YSB egg masses of varying size, for which we have recorded the actual number of hatching larvae (range: 30- 150 larvae). Based on dissection of many other YSB egg masses after egg hatching, we have found that, in a healthy egg mass, almost all eggs will hatch. Therefore, the number of eggs in an egg mass is generally equivalent to the number of hatching larvae.

We collected YSB adults from ricefields in the vicinity of IRRI and caged them on rice plants in a greenhouse. We obtained 95 egg masses and visually compared each one with our reference collection. The egg masses were placed individually in vials and the number of emerging larvae was recorded.

Based on visual comparison with the reference collection, our mean estimate was 104.2 ± 2.6 (n = 95) egg masses, a number very close to the mean number of larvae that we later observed to emerge from these egg masses, 104.9 ± 2.8. The relationship between the number of estimated and observed eggs per egg mass, y = 0.87x + 13.3,

50 IRRN 1997

http://www.cgiar.org/irri

http://www.riceweb.org

http://www.riceworld.org

Parameter estimates for multiple regression of number of larvae per egg mass on egg mass length and width.

Variable Estimate SE t a

Length 19.88 2.03 9.80** Width 16.44 5.00 3.29**

a ** = significant at the 1% level.

dent variables in a multiple linear regression, with the number of hatching larvae as the dependent variable. The

where y is the estimated number, was linear and highly significant (R 2 = 0.875, df = 93, P<0.0l) (see figure). The regression indicates that we slightly over- estimated the number of eggs in small egg masses and slightly underesti- mated the number in large egg masses.

Other researchers have used multiple regression equations to predict the number of eggs per YSB egg mass from measurements of egg mass length and width. To evaluate this method, we measured the length and width of our 95 test egg masses before egg hatch and used these measurements as indepen-

Relation between estimated number of eggs and observed number of hatching larvae.

resulting equation, y = 19.881 + 16.44w- 56.96 (see table), explained only 61%of the variation in the number of hatching larvae (adjusted R 2 = 0.61).

Our results demonstrate that, at least in the hands of an experienced researcher, comparison with a reference collection can be a highly accurate technique for estimating the number of eggs in a YSB egg mass. The predictive power of an alternative method, the multiple regression technique, could perhaps be improved by adding egg mass thickness as an additional independent variable. Maximum thickness of the egg mass could be measured with a set of calipers, but the variable thickness of the egg mass is better taken into account by visual comparison with a reference col1ection.

Excel modeling environment: description and application to the ORYZA0 model

Leaf photosynthesis explanatory model

Parameter description Dimension Formula Value

Intensity of absorbed radiatlon (PAR) J m -2 s -1 150 S. Bocchi, M. Biloni, and H. ten Berge; Institute of Max. leaf photosynthesis (at saturated Iight) kg CO 2 ha -1 h -1 50

Agronomy, University of Milan, Italy AB-DLO, kg CO 2 ha -1 h -1

Research Institute for Agrobiology and Soil lnitial light use efficiency J m -2 s -1 0.40 Fertility, Wageningen, The Netherlands

Gross photosynthesis rate kg CO 2 ha -1 h -1 D12 = D7* (1-EXP(-D9*D5/D7)) 34.94

ORYZA0 is a N-limited rice production model developed at AB-DLO (Wage- 1. Example of a simple model written in Excel. The direct approach is used. The four columns allow

ningen) during the SARP project, in easy understanding of data and calculations.

collaborative work with IRRI and NARS from rice-producing countries in Asia. It was originally written in FST while computation and less important proach enlarges the user range for (Fortran Simulation Translator), within parameters are hidden. This approach direct application, for demonstration, DOS. We have recently produced an allows users to concentrate on model and for teaching purposes. Excel worksheet version. Three ap- output and to identify knowledge gaps An example of Excel modeling envi- proaches were considered: direct, through simulations. The advanced ronment using the advanced approach custom, and advanced. The main approach is similar to the custom (Fig. 2) is the model ORYZA0.xls. A difference is the user interface. The approach but makes more use of ma- model like ORYZA0 is composed of ini- direct approach (Fig. 1) uses a simple cros, modules, and Visual Basic. Colors, tial variables, input tables, and equa- method containing few computations. borders, text styles, buttons, and tions. All these can be easily converted This approach is useful as a teaching windows are used to provide a user- in a spreadsheet. The Fortran model tool. The custom approach permits friendly interface. The interface accom- functions were translated into the many relations among parameters. panies the user in a model shell, and it spreadsheet where in most of the cases Emphasis is on a clear presentation of is easy to scroll, with clear input re- the statements are the same model input-output listings. Main quests, fast simulation run, and im- State variables, rate variables, input and output data are put together proved output. The advanced ap- driving variables, tables, and subrou-

Vol. 22, No. 2 51

Fukui International Koshihikari Rice Prize

tines are located in different parts of the spreadsheet. Formulas and computations are not directly available to users. Help windows provide guidelines to correct data inserting and to output requirements. The model is shared into modules, each one located in a single sheet (crop sheet, weather sheet, soil sheet, fertilization sheet, graph, and output sheet).

We compared the FST model with the Excel model. No difference is found in the output values. Model speed is much higher with the Excel version because of translation, linking, and compiling constraints within the FST shell. The interface is greatly improved. Using the Windows editor, it is possible to partly or totally copy the model data in a word processor, in a database, or in a different spreadsheet. In addition data and graphs can be printed.

2. OryzaO Excel advanced approach. The "main window" of the model is presented. Moving the mouse and clicking on the buttons allow one to select one of seven windows of the model. The "simulation run" button runs the model and updates the main output.

Announcement Asian Crop Science Conference held in

Crop Science Society of Asia and inter- Fukui, several representatives from the

The Fukui International Koshihikari national agricultural research centers Rice Prize was established in 1997 to

the development of the rice cultivar an international prize to be awarded to Koshihikari in Fukui Prefecture, Japan. rice researchers who have contributed Koshihikari is renown throughout to improving rice production through

The development of Koshihikari is development, or other related fields. acknowledged as a typical case of a The Prize was established particularly great contribution to domestic as well to award rice researchers working in as international rice production universities and international, national, achieved by a local agricultural experi- and local agricultural research stations. ment station. In 1995 during the 2nd

and national agricultural research commemorate the 50th anniversary of systems proposed the establishment of

Japan for its outstanding grain quality. breeding, cu1tivation techno1ogy

The Prize will be given to three outstanding researchers. The laureates, who will be invited to an awards ceremony to make a presentation on their achievements, will be awarded

deadline for the nominations is 31 Dec 1997. Nomination forms are available from the Secretariat for the Fukui International Koshihikari Rice Prize, Fukui Agricultural Experiment Station, 52-21 Ryo-machi, Fukui City, Japan; fax:

300,000 Japanese yen each. The

81-776-54-5106.

52 IRRN 1997

Instructions for contributors NOTES IRRN categories. Specify the

General criteria. Scientific being submitted should appear. notes submitted to the IRRN for Write the category in the upper possible publication should right-hand corner of the first • be original work, page of the note. • have international or pan- national relevance, GERMPLASM IMPROVEMENT • be conducted during the genetic resources immediate past three years or genetics be work in progress, breeding methods • have rice environment yield potential relevance, grain quality • advance rice knowledge, pest resistance • use appropriate research diseases design and data collection insects methodology, other pests • report pertinent, adequate stress tolerance data, drought • apply appropriate statistical excess water analysis, and adverse temperature • reach supportable conclu- adverse soils sions. other stresses

Routine research. Reports of ment screening trials of varieties, irrigated fertilizer, cropping methods, rainfed lowland and other routine observations upland using standard methodologies flood-prone (deepwater and to establish local recommenda- tidal wetlands) tions are not ordinarily ac- seed technology cepted. Examples are single- season, single-trial field CROP AND RESOURCE experiments. Field trials should MANAGEMENT be repeated across more than soils one season, in multiple soil microbiology seasons, or in more than one physiology and plant nutrition location as appropriate. All fertilizer management experiments should include inorganic sources replications and an internation- organic sources ally known check or control crop management treatment. integrated pest management

Multiple submissions. Nor- insects mally, only one report for a weeds single experiment will be other pests accepted. Two or more items water management about the same work submitted farming systems at the same time will be farm machinery returned for merging. Submit- postharvest technology ting at different times multiple economic analysis notes from the same experiment is highly inappropriate. ENVIRONMENT Detection will result in the SOCIOECONOMIC IMPACT rejection of all submissions on EDUCATION AND COMMUNI- that research. CATION

RESEARCH METHODOLOGY

category in which the note

integrated germplasm improve-

diseases

Manuscript preparation. Arrange the note as a brief statement of research objectives, a short description of project design, and a succint discussion of results. Relate results to the objectives. Do not include abstracts. Do not cite references or include a bibliography. Restrain acknowl- edgments.

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

Apply these rules, as appropriate, in the note:

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

• Use generic names, not trade names, for all chemicals. • Use the International System of Units for measurements. For example, express yield data in metric tons per hectare (t ha -1 ) for field studies. Do not use local units of measure. • Express all economic data in terms of the US$. Do not use local monetary units. Economic information should be presented at the exchange rate US$:local currency at the time data were collected. • When using acronyms or abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Use the abbreviation thereafter. • Define any nonstandard abbreviations or symbols used in tables or figures in a foot- note, caption, or legend.

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

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

Comments. If you have comments or suggestions about the IRRN, please write to the editor.

Mailing address. Send notes and correspondence to the IRRN Editor, IRRI, P.O. Box 933, Manila 1099, Philippines. Fax: (63-2) 845-0606 E-mail: [email protected] Home page: http://www.cgiar.org/irri Riceweb: http://www.riceweb.org Riceworld: http://www.riceworld.org

mailto:[email protected]

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international rice research notes vol.22 no.2

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