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Wheat (Triticum aestivum L.) is considered one of the world's most important cereal crop. In recent years, climate changes issues have a negative impact on the morphological and physiological traits of wheat including grain productivity. Therefore, it is important to develop bread varieties resistant to abiotic factors varieties. Effect of high temperature (more than 30°С), during grain filling period, on grain quality and productivity has been studied thoroughly for southern parts of Uzbekistan.

At the study, temperatures during the growth period were calculated and daily temperatures during the grain filling period were determined. The effect of air temperature on growth and development, plant height (cm), spike length (cm), number of spikelets per spike (unit), spike grain weight in a spike(g), TKW (g), test weight (g/l), protein content (%), gluten content (%) were studied.

Results shows that heading period of later sowing varieties and accessions began 9-10 later compared to the optimal sowing and the yield decreased by 1.53– 2.76 t/ha, TKW decreased by 0,25-9,85 gr due to the temperature increase during “heading-maturity” stage. Several varieties and accessions had the highest resistance to heat under optimum planting date while varieties and samples under late sowing period had lowest heat resistance.