Zavgorodniy V. Optimization of the elements of technology of growing stevia under condition of the forest-steppe zone of Ukraine

The thesis deals with results of research of the influence of practices of pinching, soil mulching with black film and formation of density of stand on growth, development and productivity of stevia plants. It was experimentally proved that the best time for plant pinching is 35 days after transplanting the crop seedlings. The optimal density of planting stevia is 80 thousand plants /ha with the spacing of 35x35 cm. Pinching the plants at the beginning of intensive growth increased the proportion of dry leaves in the structure of a dry plants as compared with other period of conducting pinching on average by 4.4-5.5% and by 8.1% comparing with the control variant. Mulching with black film optimizes water, termal and nutritive regimes of soil, increases saving plants on average by 17%, increases the output of dry mass by 1.5%, ensures the increase of yields of dry leaves by 2.67 t/ha, as compared with the control. The highest yields of dry leaves (5.43 t/ha) and the output of glycosides (435 kg/ha) wereobtained in the variant with film mulching and density of stand of 80 thousand plants /ha.