Kiriiak Y. The productivity of winter wheat varieties depending on agro technological factors in the conditions of climate change in the southern steppe of Ukraine

The aim of the research was to determine the features of the formation of the crop of different varieties of winter wheat depending on its location in the crop rotation and weather conditions during the growing season. The thesis presents the results of studies of the features of the growth and development of winter wheat varieties Ovid and Kherson 99, their productivity, depending on the location in the rotation, tillage system and weather conditions. Placement of winter wheat in different parts of the crop rotation and methods and depth of tillage under its predecessors influenced the nature and intensity of moisture accumulation in the soil during the autumn-winter period. It was found that 20 in 2015 and 2016 there was a close correlation between the reserves of productive moisture in the soil under winter wheat crops during the recovery of vegetation and yields of r = 0.85 and r = 0.64, respectively. At the time of ending the autumn growing season of the plant varieties, Kherson 99 formed on a 1.6-21,2% more number of shoots compared to the sort of Ovid. In the spring, before the release of plants into the tube, the average daily increase in dry matter in the Ovid variety was 3.2 - 5.5% higher than the Kherson variety 99, and in the interfacial period "output in the tube – earing" – 4.2-6.5 %. The intensity of plant growth depended on the variety, weather conditions, and predecessors. The multiplication factor of the seed was higher in grade Ovid – 14.4-22.5, and somewhat lower in the variety Kherson 99 – 12,4-20,1. In both varieties, it was higher in the seeds of winter wheat, placed on the bare fallow. Seed production of winter wheat increases the conditional net income compared to grain production 22.6-23.9% of the grade Kherson 99 and by 30.7-32.5 percent of the varieties of Ovid. Keywords: climate changes, growth, development, productivity, winter wheat, variety, Kherson 99, Ovid.