A study was conducted at Wheat Breeding section, RPCAU, Pusa, Samastipur, Bihar during rabi 2016-17 to evaluate the genotypes of bread wheat (Triticum aestivum L.) for terminal heat tolerance. Observations were recorded on plant height, number of tillers per plant, flag leaf area, days to fifty per cent flowering, canopy temperature, relative water content, spike length, number of grains per spike, spike fertility, chlorophyll content, days to maturity, thousand grain weight, harvest index, yield per plant, thousand grain weight susceptibility index and heat susceptibility index. 24 genotypes were grown under two environments i.e. timely sown (non-stressed) and late sown (stressed). The experiment in each environment was laid out in Randomized Block Design with three replications. In order to find out the degree and direction of relationship of the yield contributing characters with yield and inter relationship between them, correlation (phenotypic and genotypic) coefficient analysis was carried out for all traits under investigation. Correlation analysis showed that phenotypic and genotypic correlation for most of the character pairs were in same direction and genotypic estimates were higher than the phenotypic one, indicating inherent association between the characters. Hence, selection based on these characters would be more effective for yield improvement in bread wheat under heat stress condition. Grain yield showed highest positive genotypic correlation with relative water content (0.9029) and lowest with days to maturity (0.0019) under timely sown condition. Under late sown condition grain yield showed highest positive genotypic correlation with relative water content (0.9428) and lowest with days to fifty percent flowering (0.0919). The traits viz., harvest index and spike fertility have to be given importance in selection process for improvement in yield, since they had positive correlation with grain yield. The path coefficient analysis facilitates the partitioning of the correlation coefficients into different components of direct and indirect effects. Days to maturity has high positive direct effect on grain yield (2.0544) whereas plant height showed low direct effect on grain yield (0.3679) under timely sown condition. Harvest index has high direct effect on grain yield (0.6822) and low direct effect of canopy temperature on grain yield (0.0147) under late sown condition and also all other characters contributed indirectly towards grain yield via these characters. Hence, selection based on these characters would be more effective for yield improvement in bread wheat under heat stress condition. It could be concluded from correlation and path analysis under timely sown condition that the traits like relative water content, spike fertility, chlorophyll content, harvest index, flag leaf area would be effective and reliable, since they had high positive correlation with grain yield, positive inter correlation among themselves and high indirect effect of most of the characters via these traits on grain yield.

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