Effect of High Temperature Stress on Physiological and Yield Parameters of Some Wheat Genotypes Recommended for Irrigated and Rainfed Condition

Effect of high temperature stress on different growth and physiological parameters, yield and yield components were studied. Seeds of eight irrigated wheat genotypes (recommended for irrigated conditions) and twelve rainfed genotypes (recommended for rainfed conditions) were sown on November, December and January and considered as normal, late and very late sowing in order to expose them to different temperature regime. Significant reductions in all the parameters at all growth stages were recorded in all genotypes. Yield and yield components were also adversely affected under late and very late planting. Genotypes recommended for irrigated conditions showed more reductions in leaf area index, relative growth rate, net assimilation rate, chlorophyll content, membrane stability index, relative water content , transverse relaxation time, yield and yield components than the genotypes recommended for rainfed conditions. However, close associations between all growth parameters yield and yield components were observed and the good performance of the genotypes which is recommended for rainfed condition under high temperature stress which could be because of their ability to maintain high water status in plant tissue and prevent cell from loosing its turgidity.