Yield contributing characters of wheat under normal and heat stress conditions

This study was conducted to identify yield and yield contributing attributes of wheat genotypes in response to heat stress. In this respect, eight wheat genotypes viz., Pavon-76, Prodip, BARI Gom-25, BARI Gom-26, BAW-1143, BAW-1146, BAW-1147 and BAW-118 were used as study materials. The experiment was evaluated in relation to heat tolerance in field condition by seeding them at November 27 (normal), December 17 (late) and January 7 (very late growing condition) over two successive years. Spike length, spike number per plant, floret number per spike and grain number per spike, floret/spike, spike dry weight and individual seed weight (seed size), grain yield, biological yield and harvest index were observed highest at normal growing condition. At late and very late growing heat stress conditions, all the genotypes showed reduced performance in those parameters at different magnitudes. Heat tolerant genotypes had higher relative values in those attributes than the MHT and heat sensitive genotype at late growing condition. Late and very late growing heat stress conditions increased the sterility in all the genotypes. HSI calculated in stress environments to assess their stress potential on the basis of grain yield. The HSI values of Prodip, BAW-1146, BAW-1147, BAW-1148 and Pavon-76 were higher than 1.0, indicating that these genotypes were susceptible to heat stress. The HSI values of the remaining three wheat genotypes indicate their various levels of tolerance to high temperature. Among them BARI Gom-25, BARI Gom-26 and BAW-1143 were tolerant to heat stress.