Cell membrane stability as a measure of drought and heat tolerance in grasses

Abstract

Drought and heat tolerance test developed for Sorghum (Sullivan, 1972) were adapted with some modifications to evaluate some species of grasses grown under controlled environment during 1988-89. Significant differences were observed, between species for herbage growth rate (non-stressed, stressed and on recovery), percent heat injury as well their angular transformed data but not for injury due to dehydration stress. Even though severely affected during drought, cocksfoot rank the highest for herbage growth rate measured under all conditions followed by tall fescue, perennial ryegrass and Italian ryegrass. On an average, rf!.* cocksfoot was found most resistant to membrane damage caused by both drought and heat stress in comparison with tall fescue and Italian ryegrass, where as v>. ^ perennial ryegrass came out as intermediate. None of the in-vitro drought and heat resistance test was found associated with drought resistance. However, negative association of recovery regrowth rate after drought with heat stability ‘M '!1- (0.531*) and positive association with droughted herbage growth rate (0.468*) indicated that the populations that recovered well after drought have less membrane damage due to heat injury as well as produce more herbage under water stress condition.