Results and discussion
There was significant reduction in shoot–root dry weight in
heat-treated plants of all the genotypes. Genetic variations
were also found significant. Maximum reduction in shoot
dry weight on account of heat stress was observed in PBW
590, while it was minimum in Raj 3077 (Table 1). Percent
reduction in root dry weight by heat stress varied from 2.06
(Raj 4037) to 35.88 (PBW 550 and PBW 502). It was noted
that Raj 4037 retained maximum shoot dry weight under
control as well as stress conditions. Wahid (2007) reported
that high temperature caused significant declines in shoot
dry weight, relative growth rate and net assimilation rate in
maize, pearl millet and wheat. In this study, variability in
per cent reduction of shoot–root dry weight suggests that
some wheat genotypes are equipped with high temperature
tolerance mechanism such as osmoregulation, antioxidative
defence system and heat shock proteins (Sairam et al.
1997; Almeselmani et al. 2006).