Chuiko D. Increased Performance of Sunflower Genotypes Depending on Plant Growth Regulators in the Eastern Forest-Steppe of Ukraine.

The thesis is devoted to the problem of low performance and inbred depression in self-pollinated lines as well as to increasing seed productivity of experimental sunflower hybrids and varieties using plant growth regulators Fulvital Plus, EcoStim, and QuadroStim and studying peculiarities of their effects in the Eastern Forest-Steppe of Ukraine. The manuscript considers theoretical issues and scientifically justifies the prospects for using synthetic plant growth regulators in sunflower seed production and breeding. For the first time in the Eastern Left-Bank Forest-Steppe of Ukraine, effects of new plant growth regulators on the growth and development of self-pollinated sunflower lines of different genetic origins and bred for different purposes were studied. Calculations allowed us to note the high economic effectiveness of growth regulator Fulvital Plus on most of the studied sunflower genotypes. Its application increased the net profit from selling sterile analogues of self-pollinated lines to 51.3%, and from selling pollen fertility restorers and sterility fixers to 26.2%. Treatment of experimental hybrid plants with Fulvital Plus and EkoStim contributed to a rise in the net profit to 73.0%. It was noted that the low cost of the studied plant growth regulators and the expenses for treatment of one hectare were within 174-340 UAH/ha, making their use cost-effective and economically rational in sunflower seed production, as the net profit from certain self-pollinated lines increased by 59.1%.