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Advisor: BADAYA, S. N.
Publisher: AAU, Anand
Language: en
Type: Thesis
Keywords: GENETICS, SALT, RESISTANCE, RICE, Oryza sativa L.
Abstract: The present investigation was undertaken to study the genetics of salt resistance in rice (Oryza sativa L.). The study was comprising of 60 genetically diverse rice cultures for screening in petriplates using 12.0, 14.0 and 16.0 EC mmhos/cm saline solutions (NaCl) and the seed germination percentage, plumule length and radicle length was observed. On the basis of these observations 20 cultures were isolated and the same were screened under the same levels of salinity in plastic trays filled with sand. The seed germination, seedling height and root length was recorded. The same cultures were also screened at 7-8 EC mmhos/cm level in earthen pot. The growth parameters, yield and yield attributes were recorded for 16 characters. From these experiments, five resistant /tolerant and two susceptible cultures were selected and a set of diallel cross including reciprocals were prepared for further study in pots with normal and saline environments. Reduction in seed germination, plumule length and radicle length was observed. The reduction was increased with increase of salinity levels in petriplate experiment. Similar reduction was also observed in plastic tray experiment, using 20 rice varieties. The same 20 rice varieties were also screened in earthen pots having saline and normal soils and the observations on growth parameters, yield, yield contributing characters and grain quality were recorded. The significant mean square analysis indicated the variability among genotypes and the environments and the significant genotype X environment interaction revealed that the there was inconsistent behaviour of genotypes over the environments. The reduction in the growth parameters, yield, yield attributes and quality characters were observed. The least affected genotypes (IET-7337, Jaya, SLR-51214, CR-138-928 and Mahsuri) and most affected genotypes (IR-28 and GR-11) due to salinity were isolated and used in diallel mating design for studying genetics of salt resistance in rice. The diallel analysis was carried out as suggested by Haymans (1954) and Griffing (1956). Analysis of variance revealed that considerable genotypic variability was present among the parents as well as their crosses for all the characters, except, no.of sterile spikelets per panicle in saline condition, indicating the selected materials was appropriate for genetic analysis. Analysis of variance for combining ability showed that the both general combining ability (gca) and specific combining ability (sca) variances were highly significant for all the traits, showing the importance of both additive and non-additive types of gene effects for the expression of different characters. The gca/sca ratio indicated the preponderance of additive gene effects for plant height, grain yield per plant, straw yield per plant, dry matter produced per plant, harvest index, no.of fertile and sterile spikelets grains per panicle and 1000 grain weight, while for all other characters, non-additive type was predominant. The degree of dominance revealed that the overdominance of consistent nature in both the environment for most of the characters, but the expression of partial dominance was observed for plant height, grain yield per plant, 1000 grain weight in both environments, dry matter produced per plant, no.of sterile spikelets per panicle and grain length in normal and maturity days, harvest index and grain breadth in saline conditions. Additive and dominance gene effects were significant for all the traits, except root/shoot ratio and grain breadth under both normal and salinized conditions. The additive component was higher than the dominance component for grain yield per plant, plant height, straw ill yield per plant and 1000 grain weight under both the environments. Higher value of additive gene effect was observed for grain yield per plant in saline condition. Salinity suppressed to a greater extent the dominance effect, contributing to the expression of grain yield, suggesting that varieties with predominantly more additive genes for grain yield would perform better in saline soil. The dominant genes were more than the recessive in the parents for all the traits, expect, grain yield per plant, dry matter produced per plant and harvest index. Asymmetrical gene distribution of genes with positive and negative effects was observed for all the characters. Number of groups of dominant genes controlling the characters was one to two. Heritability in narrow sense was highest in 1000 grain weight and lowest in flag leaf area, whereas most of the characters expressed moderate (medium) heritability in both the enviornments. When the parents were scored for gca effects across the traits, Jaya (P2) ranked first as best general combiner for yield and yield components followed by parents IET-7337 (P1) and SLR-51214 (P3). Crosses IET-7337 x GR-11, Jaya x IET-7337, Jaya x IR-28 and Jaya x GR-11 were the best specific combinations, when they were scored for sca across the traits. The crosses Jaya x IET-7337, Jaya x Mahsuri, Jaya x IR-28, SLR-51214 x CR-138-928, SLR-51214 x Mahsuri, and SLR-51214 x GR-11 showed good heterobeltiosis and crosses, IET-7337 x Mahsuri, Jaya x IET-7337, Jaya x IR-28 and Jaya x GR-11 exhibited good heterosis over mid parent in normal environments, while, in saline environment only four crosses, Jaya x GR-11, Jaya x IR-28, Jaya x IET-7337 and IET-7337 x Mahsuri showed significant and positive heterobeltiosis for grain yield per plant and some other traits. From the results, it is clear that almost all combinations involving Jaya, IET-7337 and SLR-51214 as one of the parents possessed significant heterosis and heterobeltiosis, good sea effect for grain yield per plant and its component.
Subject: Genetics and Plant Breeding
Research Problem: GENETICS OF SALT RESISTANCE IN RICE (Oryza sativa L.)
These Type: Ph.D
Issue Date: 1995
Appears in Collections:Theses

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