PERFORMANCE OF KERNEL DRY MATTER ACCUMULATION AND YIELD ATTRIBUTES OF WHEAT CULTIVARS UNDER NORMAL AND HEAT -STRESSED ENVIRONMENTS

Abstract

An experiment was conducted with two wheat cultivars viz. a relatively heat tolerant (HT) Kanchan and a heat sensitive (HS) Sonora to elucidate differences in yield attributes and kernel dry matter accumulation under normal and late planting heat-stressed environments. Results clearly depicted that irrespective of cultivars, all the tested spike, spikelet and kernel attributes were affected due to late planting heat stress, but the extent of reduction was significant and relatively higher in HS Sonora under heat-stressed environment. A typical sigmoidal pattern of kernel dry matter accumulation was observed in both wheat cultivars under normal and heatstressed environment. Days to attain peak of kernel dry matter accumulation was reduced by 5 days in Kanchan, whereas it was reduced by 10 days in Sonora due to heat stress. Seed yield from Kanchan and Sonora was recorded as 4.89 t ha and 4.78 t ha", respectively under normal environment. But it was reduced more in Sonora (32.0%) than Kanchan (18.8%) under heat- stressed environment. Finally, it was found that seed yield reduced by about 5.8% for each I·C rise in average mean air temperature from normal growing environment during anthesis to maturity in Kanchan but it was about 1.6 times higher i.e. 9.3% in Sonora.