Specific reaction of spring soft wheat varieties to weather conditions

The purpose of the research was to study the dependence of grain productivity of modern varieties of spring wheat with different genotype on agrometeorological conditions of the middle Volga forest-steppe. The researches were carried out in Samara Region in 2014-2018. The objects of the research were 36 varieties of spring soft wheat of competitive variety testing. To characterize the weather conditions of wheat's vegetative period, the following indicators were used: average monthly air temperature, the amount of precipitation per month, and the hydrothermal coefficient. 2017 was the richest year in moisture for the years of the research with the hydrothermal coefficient for vegetation equal to 1.04 (with a long-term average value of the indicator of 0.73); in other years vegetation season of spring wheat was in arid or acutely arid conditions (hydrothermal coefficient of 0.38-0.59). Average yield of the varieties competitive testing over the years of the research varied from 20.5 c/ hectare (2016) to 34.1 c/hectare (2017). The correlations between the average varietal yield of wheat and studied weather factors of vegetation season were reliable and with an average air temperature of r = -0.67, with the sum of precipitation of r = 0.76, with the hydrothermal coefficient of r = 0.78. The strongest dependence of average varietal yield was observed with air temperature (r = -0.85), precipitation (r = 0.88) and the hydrothermal coefficient (r = 0.89) in June, when wheat goes through the most important phases of growing to the tube, earing and blossoming. June precipitation was higher than the long-term average norms and average temperatures had positive effect on initial growth and development of wheat plants, as well as on the formation of the ear, further significantly increasing the varieties' productivity. At the same time, different specific reaction of zoned varieties to developing weather conditions of vegetation was observed. It was noted that newly created varieties were more adapted to the conditions of the region, less dependent on adverse temperature factors and were quite responsive to precipitation in the first half of plants vegetation.