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.
