Response of new varieties of winter wheat (Triticum aestivum L.) to the impact of environmental factors under the conditions of the Southern Forest-Steppe zone of Ukraine

Purpose. To define the level of impact of such factors as rate, time and methods of sowing on seed productivity and certified seeds, and the individual response of winter wheat varieties to these factors if used the ecological system of seed farming, that would allow to form and obtain genetically determined potential of variety productivity. Methods. Weight measurement for determining seed yield; statistical, variance and regression analysis for identifying the reliabi­lity of the experiment results. Results. During the research period, weather conditions were greatly differed both by temperature regime and precipitation, but stability of grain and seeds yield on an annual basis was the main requirement to varieties. During the study of «grain productivity» value and quantitative indices of winter wheat yield structure, the results from 684 plots were obtained which were grouped and analyzed for impact factors for complete certainty, and NIR0,05 was calculated. Conclusions. Thus, in case of shifting sowing time from optimum to later period, efficiency of water use by plants was decreasing to a greater extent during years with insufficient precipitation. The shift of sowing time to later period providing optimal seeding rate and row seeding method did not reduce yield. The yield of winter wheat varieties to be studied when sowing in usual manner with seeding rate of 5,5 million seeds/ha in the period from September 15 and October 5 was the highest. Varieties ‘Slavna’ and ‘Chorniava’ provided the highest grain productivity for seeding rate of 5,5 million seeds/ha and using row seeding method, with slight impact of sowing time factor. Grain yield of studied varieties showed negative response during the experiment when seeding rate decreased up to 2,5–3,0 million seeds/ha. ‘Astarta’ varie­ty provided the highest productivity for certified seeds yield as compared to the control (from 1,59 to 3,38 t/ha). The variant of the experiment when sowing on October, 5 in usual manner with seeding rate of 5,5 million seeds/ha showed the highest productivity of 7,02 t/ha (+3,38 t/ha, or +92,9%). Shifting of sowing time for October, 5 resulted in a significant decrease in yields of certified seeds as compared to sowing time on September 15 and 25. Seed yield of studied varieties when sowing on October, 5 was higher than in case of sowing on September, 25. The highest percentage of certified seeds output in the studied varieties was observed for a seeding rate of 2,5–3,0 million seeds/ha. For seeding rate of 5,5 million seeds/ha for varieties with seeding time between September 15 and 25, the difference in grain yield was negligible. The winter wheat variety ‘Astarta’ provided the highest yield of seeds during the research years – 9,36 t/ha, the standard variety ‘Bogdan’ – the lowest one in the best variant of 5,55 t/ha.