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Sunflower is the leading oilseed crop in Ukraine. Weather conditions of Zaporizhzhya region in 2005 - 2015 are characterized by cyclic variability of basic elements accompanied by some decrease in rainfall and their redistribution for the seasons. This led to the decrease of the stock of productive moisture in the arable and meter layers of the soil, occurrence of prolonged hydrothermal stresses during critical phases of plant development, especially for the late spring crops including sunflower. Sunflower yields began to fluctuate since 2011 against the background of strengthening of the negative effects of stress factors that provoke the development of oxidative stress. The coefficient of variation in yield for the period from 2005 to 2010 is 9.55 %, and for the period from 2011 to 2015 - 15.40 %. The amount of active temperatures during the growing season of sunflower In Zaporizhzhya region averages 2965 0С, 1165 0С more than the optimum. Medium negative correlation between yield and amount of active temperatures was established (r = -0.426). It has been proved that yield formation of sunflower is not so much affected by rainfall during the growing season (r = 0.534), but mainly by minimum relative humidity during plant flowering (r = 0.855). This should be considered when determining the sowing terms, selection of varieties and hybrids of sunflower and anti-stress preparations use on the studied crop. State service of Ukraine on protection of plant variety rights has published a list of sunflower varieties and hybrids, recommended for cultivation in 2015. It has 665 varieties and hybrids, while in 2012 the figure was 417. Therefore the choice of hybrids that are the most productive in the conditions of Southern Steppe of Ukraine, requires further research.