Heat And Drought Stress Effect In Wheat Genotypes: A Review

Bread wheat (Triticum aestivum L.) belonging to family Poaceae is the most important cereal crop as it contributes major portion to the world food for the world’s population. Similarly, it is the third most cultivated cereal crop in Nepal in terms of production and area. Wheat is a winter season crop which is usually grown within a temperature range of 15-250C in cold and dry weather. However frequent irrigations are crucial for proper growth of the plant, high yield and high quality of the grain. The annual productivity of wheat has been reported to be 2.49 tons per hectare. Water is found to be one of the most important factors in wheat production and by far not a single water stress tolerant variety has been introduced thus water management is necessary. In Nepal around 35% of the total wheat is cultivated under rainfed condition annually and in Terai this is around 19%. This cultivated area faces a severe drought stress during growing stage and heat stress during anthesis stage. Various studies have suggested that the combined impacts of drought and heat stress had a significant harmful effect on wheat than individual stresses (Stress and Review, 2017). Under drought stress days to anthesis and days to maturity were reduced by 10% and 14% while under heat stress these were reduced by 16% and 20% respectively. Combined effect of drought and heat stress caused reduction in DTA by 25% DTH by and 31%.