RAVI KUMAR, B. N. V. S. R.SUNEEL KUMAR, GANTA2020-03-042020-03-042019http://krishikosh.egranth.ac.in/handle/1/5810144163D5950The current research study was carried out during kharif, 2018 at Regional Agricultural Research Station, Maruteru, Andhra Pradesh with one hundred and forty two RILs and two checks to study the variability, heritability and genetic advance for yield and yield contributing traits and to identify QTLs for BPH tolerance. The ANOVA explained significant differences among the RILs for all traits viz. days to fifty percent flowering, plant height (cm), number of ear bearing tillers per plant, panicle length (cm) and grain yield per plant (g) indicating sufficient genetic variability among the RILs. Both GCV and PCV were higher for grain yield (g) per plant and high heritability accompanied with high genetic advance as percent of mean was observed indicating presence of additive gene action in inheritance of this trait and therefore direct selection is effective. Moderate heritability and genetic advance as percent of mean was recorded for plant height (cm) and ear bearing tillers per plant indicating presence of both additive and non additive gene actions. Moderate heritability with low genetic advance as percent of mean was observed for days to 50% flowering and panicle length (cm) indicating non additive gene action and selection may not be effective for the above traits. Evaluation of one hundred and forty two RILs for BPH tolerance was done in both lab and filed conditions. The results revealed that in lab screening forty four RILs were resistant, sixty two were moderately resistant, thirty were moderately susceptible and six were susceptible, whereas in field screening sixty seven RILs were resistant, thirty four were moderately resistant, twenty one were moderately susceptible, twenty were susceptible. Construction of linkage map and QTL analysis, using seventy seven polymorphic markers, revealed that composite interval mapping and interval mapping has identified three QTLs for BPH tolerance viz., qmbph2.1, qmbph4.1 and qmbph12.1 on chromosomes 2, 4 and 12 respectively. In addition to above three QTLs, two more QTLs, qmbph5.1 and qmbph7.1 were identified by interval mapping on chromosomes 5 and 7 respectively. Fine mapping of the above QTLs and identification of putative genes will be the future line of the present study.en-USnullThesis