Effect of temperature on development and grain formation in spring wheat

摘要

Ten wheat genotypes viz., Inqilab-91, AS-2002, GA-2002, Manthar, Ufaq-2002, 00125, 00055, 01180, 00183 and 99022 were planted on November 10, 2003 (normal planting) and January 10, 2004 (late planting) at Wheat Research Institute, Faisalabad to study the effect of temperature on development and formation of grain. Significant genotypic differences were observed for all traits studied indicating considerable amount of variation among genotypes for each character under normal and late planting conditions. The maximum reduction of 53.75% was noted for grain yield while tillers m-2showed less reduction (15.38%) under late planting conditions. Heat stress intensity was high (0.538), which ultimately lowered the grain yield under late planting conditions. Variety AS-2002 showed a low (0.86) heat susceptibility index for grain yield. However, Inqilab-91, 00125, 00180, and 00183 were better yielder under normal planting conditions. High genotypic coefficient of variability (GCV), phenotypic coefficient of variability (PCV), heritability in broad sense (h2), genetic advance as percentage of mean (GA%) were observed for grain filling duration, grains per spike, 1000-grain weight and grain yield per plot under normal and late planting conditions. Genotypic correlation coefficients were generally in the same direction as phenotypic correlation coefficients but higher in magnitude under both planting conditions. 1000-grain weight was significantly and positively associated with harvest index at genotypic level. Under late planting conditions, grain yield per plot showed significant and positive genotypic correlation coefficients with biomass per plot and harvest index. Characters showing strong association with grain yield indicating selection for these traits are expected to result in yield improvement under normal and late planting conditions.