Cell membrane stability: Combining ability and gene effects under heat stress conditions

Abstract

Heat stress is an important production constraint of wheat during grain-fill period in India and in other parts of the world where the temperature become high during anthesis to maturity (grain-filling) stage of plant growth. This study determined the genetic control of heat tolerance through half diallel analysis of selected wheat genotypes. Heat induced damage of plasma membrane was assayed by membrane thermo-stability (MTS), which measure electrolyte leakage from leaf tissues after exposure to high temperature. Eight genotypes comprising heat tolerant and sensitive response to high temperature stress were hybridized in a half diallel. Electrolyte leakage or MTS was conducted at grain-filling stage of plant growth as ambient temperature become high enough to cause heat hardening of leaves. The mean square for GCA was higher in magnitude than that of SCA, but the components of genetic variance indicated considerable influence of dominance variance in determining inheritance of this trait. Results suggested that the selection for heat tolerant inbred lines based on MTS in this material may be more effective by reducing the dominance variance after a few generation of selfing particularly in a self-pollinated wheat crop. The varieties, Hindi 62 and NIAW 34 were good general and specific combiners in the tolerant group, while HD 2687 and WH 147 were good specific combiners in the heat sensitive group.