Influence of heat stress on physiological and yield potential of promising bread wheat cultivars

Population pressure and deforestation has catastrophic impacts on the global environment. Elevated air temperature is the most serious threat to agriculture sector especially cereal crops. Wheat is a major cereal and consumed as staple food by 2/3rd of total population but its annual yield has drastically been reduced in response to severe heat stress exposure during various growth stages in last two decades. Therefore, there is dire need to pay an immediate attention to screen promising wheat varieties particularly in hot environments. Hence, physiological and yield potential of ten wheat cultivars (Hashim-08, Lasani-08, Farid-06, Ujala-15, Sehar-06, AARI-08, Galaxy-13, NARC-09, NARC-11 and Pakistan-13) was evaluated for two years (2019 and 2020) under early and late sown conditions in present study. Canopy temperature depression, cell membrane thermostability, pre-anthesis stem reserve mobilization, relative cell injury, relative growth performance, and stress susceptibility index were measured as stress indicator to evaluate the performance of tested wheat cultivars. Wheat cultivars NARC-09, NARC-11 and Pakistan-13 were declared as heat tolerant while Hashim-08, Lasani-08, Farid-06, Ujala-15, Sehar-06, AARI-08 and Galaxy-13 were found to be susceptible towards terminal heat stress. This wheat stock will be a useful parental material to develop tolerant varieties in wheat breeding programs.