Kernel growth physiology of wheat under late planting heat stress

Abstract

Three heat tolerant (Aghrani, Kanchan and CB-30) and one heat sensitive (Sonora) wheat genotypes were tested under normal and post anthesis heat stress condition by seeding them on November 30 and December 30, 2001 at the research farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh to study their kernel growth physiology in relation to heat stress. Irrespective of growing conditions, both dry matter and starch accumulation in kernel showed a typical sigmoidal pattern in all genotypes. Due to post anthesis heat stress, the quantity of dry matter accumulation at peak and the duration required to attain peak were higher in heat tolerant (HT) genotypes than the heat sensitive (HS) one. Sonora, a HS genotype, responded to post anthesis heat stress by accumulating larger quantity of soluble sugar during active kernel development period in contrast to HT genotypes indicating poor capacity of kernel of Sonora to utilize sugar for starch synthesis. The heat tolerant genotypes exhibited distinctly higher relative individual kernel dry weight under post anthesis heat stress condition when compared to heat sensitive genotype.