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ThesisItem Open Access Molecular mapping of quantitative trait loci for yield, yield components and terminal heat tolerance in bread wheat (Triticum aestivum L.)(CCSHAU, 2014) Bishnoi, Shewane; Chowdhury, V.K.A total of 103 F10 RILs of bread wheat derived from HUW-510X WH-730 were evaluated for yield, yield components and tolerance to terminal heat stress in normal and late sown field experiments during the Rabi season of 2010-11 and 2011-12 using an alpha design in two replicates. The traits evaluated were : days to heading, days to anthesis, grain development rate, grain filling duration, number of tillers /1/2m row-length, number of kernel per spike, number of spikelet per spike, spikelength, days to physiological maturity, thousand grain weight and yield/1/2 m row. HSI of the traits was used to assess tolerance to heat stress. Highly significant genotypic differences were observed for all traits. Gene dispersion between the parents caused transgressive segregants for all the traits. Selective genotyping QTL method was used to screen 300 SSRs in a subpopulation of 37 RILs. 21 linkage groups were formed using 99 polymorphic markers. SMA detected 171 QTLs at 5%, 38 at 1% and 8 at 0.1% level .CIM detected 37 QTLs (31 for yield and related traits and 6 for HSI). Some QTLs were present in coupling and repulsion phase, explaining genetic basis of positive and negative association respectively between traits. Favourable QTLs for a number of traits and for heat tolerance (HSI) were present in WH-730 parent useful to counteract the terminal heat stress. Some QTLs were detected controlling more than one trait. This may be due to linked QTLs or pleiotropic effect of a single QTL. Favourable allele from WH-730 QTLs for HSI TGW and HSI DPM in the interval barc137-gwm140 on 1B may be used to counteract the terminal heat stress.