Sheshshayee, M. S.PRATHIBHA, M. D.2018-03-012018-03-012016-10-11Th-11532http://krishikosh.egranth.ac.in/handle/1/5810041453With the rapidly decreasing water resources, devising water saving agronomic practices rice cultivation is the most crucial need of the hour. Introgression of water mining and water use efficiency (WUE) traits on to a single elite genetic background is needed while developing aerobic worthy rice cultivars. In this investigation, a focused marker assisted backcross breeding approach was adopted to introgress the root and WUE traits into the elite genetic background of IR-64. In an earlier investigation, a panel of germplasm was characterized for molecular and phenotypic diversity leading to the discovery of trait donor genotypes (AC-39020 for roots and CLT, IET-16348 for WUE) and DNA markers for the traits by Association Mapping. Of the 50 markers associated with root and WUE traits, 16 markers found to be polymorphic and used as foreground markers. A set of 120 polymorphic genome wide SSR markers were used for background selection to reconstitute the recurrent parent genome. Three backcrosses were done and at DCBC3F1 generation four plants with maximum foreground and background were selected for further advancement by selfing. At DCBC3F2 generation a set of 1500 lines were screened under aerobic field conditions and the best lines (250) were advanced to DCBC3F3. These lines were extensively phenotyped for root, Δ13C and yield under aerobic conditions and identified 26 promising trait introgressed lines with background genome recovery of more than 95 percent and 30 per cent more yield than IR-64. These lines when grown under well-watered and water limited condition maintained higher growth and spikelet fertility compared to IR-64. This study significantly contributed for the development of trait introgressed lines that can be used for commercial cultivation and QTL-NILS that have great potential in academic understanding of QTL interactions.ennullThesis