Genetic analysis and traits association study in marker-assisted multi-drought-traits pyramided genotypes under reproductive-stage moisture stress in rice (Oryza sativa L.)

Abstract

Reproductive-stage drought-stress is a major production constraint in rainfed rice ecosystem. Emergence of marker-assisted breeding strategies for developing drought-tolerant rice varieties are being optimized through exploiting adaptive-traits for their increased contribution towards grain-yield under recurring-drought. Grain-yield is a complex-trait; requires knowledge of genetics and association among yield contributing component-traits. Current study was undertaken using 21 marker-assisted multidrought-traits pyramided genotypes responses for genetic variability and association of traits for grain-yield under aerobic and reproductive-stage drought conditions. Field evaluation was carried-out in two seasons and data was collected on various parameters. Path-coe cient analysis was used as a selection criterion to select yield contributing-traits and found nine phenotypic traits were having a positive direct-effect on grain-yield during both and/or at least one season under both moistureregimes. The data from summer and Kharif seasons have been pooled within their respective moisture-regimes due to the nonsigni cance of Levene's test of homogeneity of variances and estimated BLUP values. ANOVA based on BLUP values revealed signi cant differences for moisture-conditions and also among genotypes. Phenotypic variation via. box-plots and histogram depicted mean phenotypic differences of traits under two moisture-regimes. Majority of the traits possessed high PCV and GCV with high heritability and GAM indicating higher trait expression and additive gene action lead to effectiveness of selection under drought/moisture stress. Grain-yield possessed a positive correlation with all the component-traits under consideration during both moisture-regimes. Selection of genotypes based on these component-traits were rewarding and seems to be better selection-criteria. Finally, we can end-up with superior-genotypes suitable for intermittent-drought conditions.