Moisture stress is the major constraint to rice production and its stability in rainfed, mainly irrigated, and aerobic environments. Identification of genomic regions conferring tolerance to stress would improve our understanding of the genetics of stress response and result in the development of drought tolerant cultivars. In the present study, quantitative trait loci for drought response related traits and as well as grain yield were identified using a set of 140 recombinant inbred lines derived from a cross between the popular high-yielding variety, IR64 and the landrace, INRC10192. A total of 36 QTL were identified for grain yield and its components under control and stress conditions. Strikingly, a QTL cluster flanked by the markers RM38 and RM331 on chromosome 8 was found to be associated with grain yield, plant height, no. of productive tillers, chaffy grains, and spikelet fertility on secondary rachis and biomass under stress treatment. The genomic regions associated with these QTL under drought stress will be useful for the development of marker-based breeding for drought tolerant, high-yielding varieties suited to drought-prone areas.Drought is the most devastating among abiotic stresses and it depresses yield by 15 -50% depending on the vigor and period of stress in rice. In the course of origin, domestication, and further evolution of rice, natural selection has been in favor of retaining traits of adaptability for its survival, whereas breeding by man has been towards selective improvement of traits of agronomic value such as higher yield, duration of choice, plant type, etc. Detailed studies of drought tolerance have enabled us to understand the physiological responses of plants, although our understanding of its genetic basis remains poor. Like yield and its components, traits that confer tolerance to the stress, directly or indirectly, are controlled by many genes, with each contributing a relatively small effect on the overall phenotype.Most of the past efforts to combine drought tolerance in highyield backgrounds have been a futile exercise, largely because of its genetically complex nature and lack of precise screening or selection protocols. Availability of high density marker linkage maps, annotated genome sequence, and powerful biometric methods has enabled identification and use of trait-specific genes/QTL for directed improvement of rice. It started with the pioneering discovery of yield QTL in wild/weedy species in rice by Xiao et al. (1998) closely followed by Brondani et al. (2002)

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Differential response of seedling characteristics under water stress conditions is known to be associated with drought resistance in rice and elucidation of its genetics could be of help in breeding for tolerance to the stress. A recombinant inbred population derived from the cross between a semi-dwarf variety IR64 and landrace INRC10192 was grown in hydroponic culture and phenotyped for varied responses of seedlings to water deficit imposed by poly ethylene glycol (PEG). The ratio between mean value of seedling trait under stress and control conditions was used for assessing drought tolerance. In all 19 putative QTLs relating to five seedling traits viz., shoot length, maximum root length, shoot dry weight, root dry weight and root to shoot dry weight ratio under PEG induced stress conditions were identified confirms that the traditional tall landraces as