HERITABILITY AND SELECTION RESPONSE FOR MORPHOLOGICAL AND YIELD TRAITS IN NORMAL AND LATE PLANTED WHEAT

Late planting seriously influenced wheat production in Pakistan due to terminal heat stress, especially during anthesis and grain filling stages. Analysis of variance across two environments revealed significant differences (P≤0.05) among wheat genotypes for spike length, grains spike-1 and grain yield. Genotype × environment interaction was significant for spikes m-2, spike length, grains spike-1 and grain yield which indicated differential performance of wheat genotypes across the two environments for 15 genotypes including checks. Heritability for spikes m-2, spike length, 1000-grain weight and grain yield were 0.41 vs. 0.61, 0.78 vs. 0.85, 0.78 vs. 0.25, and 0.82 vs. 0.63 under normal and late planting environment, respectively. Expected selection response for most of the traits was greater than observed selection response under both environments. Mean of the 3 top ranking genotypes was greater than the mean of two check cultivar’s yield contributing traits. Selection differential for most of the yield contributing traits was greater under late than normal planting. None of the 3 top ranking genotypes for yield components were common under the two planting environments. Net reduction in grain yield due to late planting recorded as 33% indicated nonadaptation of wheat genotypes to stress encountered.