Abstract

                                Rice is the principal food crop for majority of the global population and its production is frequently affected by drought. The objective of this study was to have improved understanding on drought resistance as a trait, study its molecular genetics and also to identify the potential drought resistant segregants. The genetic material used in this study comprised of near-isogenic lines of IR64 (BC2 F7 generation) with random introgression from drought resistant land race Norungan. There was a significant reduction of 25 per cent and 75 per cent in mean plot yield under moderate and severe stress conditions respectively from that under irrigated control which reflected the varied stress intensities between the treatments. The genetic material exhibited significant phenotypic variation for 16 traits studied under three experimental conditions. Marker - trait association was assessed by single marker analysis. Totally 121 markers were used out of that eighteen markers showed putative association with at least one of the investigated trait. A candidate gene based marker for DREB 1 positioned in chromosome 8 was associated with yield under severe stress whereas SSR markers viz, RM 256 in chromosome 8; RM 245 in chromosome 9 were linked with yield under moderate stress. These markers were also linked with other associated traits viz, harvest index, leaf senescence and leaf rolling. These might be useful for marker assisted selection for rainfed rice improvement.

Key words : Rice, drought resistance, molecular marker, component traits