Genetic Variability and Divergence Studies on Yield under Delayed Sowing Conditions in Rice (Oryza sativa L.)

Timely sowing is a critical factor in realizing the yield as it ensures the vegetative growth to crop up during a period of satisfactory temperatures and fits the cultivar maturity length and growing season. In the present investigation, 38 cold tolerant rice genotypes were studied under delayed sowing conditions at College Farm, Professor Jayashankar Telangana State Agricultural University, Hyderabad. The genotypes were evaluated for yield attributing traits with a view of understanding the extent of variability and diversity present among the genotypes that could be suitable for delayed sowing conditions with cold tolerance. Analysis of variance (ANOVA) indicated significant differences for all the characters with high genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) values for tillers per plant, spikelet fertility, filled grains per panicle and seed yield per plant. High heritability coupled with high genetic advance as percent of the mean was observed for plant height, spikelet fertility, filled grains per panicle with higher variability indicating the presence of fixable gene action which may suggest a reliable crop improvement through selection of these traits. As association analysis could help the breeder to design selection strategies to improve grain yield, correlation studies were carried out which revealed the trait to be having positive relation with all the traits except panicle exertion and panicle length. Path coefficient analysis showed all the traits except panicle exertion and test weight to be exhibiting a direct positive effect on yield, selection for which should be emphasized on these positively associated traits for yield enhancement. Principal component analysis and D2 analysis together determined plant height, grain yield, panicle exertion, panicle length and yield per plant having higher contributions to the total variability, which could be taken into consideration in rice breeding programmes for further improvement in production.