Lytovchenko A. Productivity of winter wheat varieties depending on the predecessor and background of the Southern Steppe of Ukraine

The thesis is devoted to the study of the processes of growth, development and formation of the grain yield and grain quality for the different biological characteristics of winter wheat varieties by the influence of the predecessor and background nutrition. It was determined the positive effect of mineral fertilizers. More significant increasing of grain yield provided when if winter wheat was placing on none-fallow (more depleted on nutrition elements) predecessors. It was studied the improvement of the nutritional regime even in bad years affected on the grain yield to be less significantly reduced. If on the natural background of the predecessor, the average grain yield of corn for silage by 38.9 %, average grain yield of winter wheat decreased by 35.7 % compared to fallow, then on the fertilized background the average grain yield decreased by 24.1 and 23.3 %, respectively, as after optimizing of plant nutrition, the significance of the predecessor is somewhat smoothed. The studied factors, in particular fertilizers, improve the quality of grain by increasing the content of protein, gluten, weight of 1000 grains, nature, conventional protein collection. The maximum efficiency provided by sowing of winter wheat varieties Kuyalnik with placement on fertilized black fallow. At the same time the conventional net profit made up 15362 UAH/ ha, the level of profitability made up 219.9 %. In an average after placing on non-fertilized fallow the profitability made up of 164.5 %, and after placing on fertilized fallow it made up of 191,2 %, after corn on silage predecessor it made up of 103.3 % and 135,6 %, respectively, and after winter wheat predecessor it made up of 112.2 and 138,0%, respectively. Key words: winter wheat varieties, predecessors, fertilizers, nutrient regime, water consumption, above-ground mass, photosynthetic potential, grain yield and quality, economic and energy efficiency.