Formation of productivity of maternal lines of sunflower hybrids under cultivation with different plant density

In 2017-2020, we studied the yield formation, its structure and quality in early-maturing selfpollinated lines - maternal forms of sunflower hybrids VK 101, VK 678, VK 905, VA 760, and ED 765 bred at V.S. Pustovoit All-Russian Research Institute of Oil Crops. The research was carried out on leached chernozem in the central natural and climatic zone of the Krasnodar region under free flowering cultivation with plant population of 40, 50, 60, and 70 thousand plants/ha. We established the negative dependence of seed yield from the sieve with oblong holes of 2.5 х 20 mm in size on increasing the plant density. The maximum yield of this seed fraction was obtained when growing maternal lines VK 101 and ED 765 with a population of 50 thousand plants/ha (1.18 and 1.12 t/ha), VA 760 and VK 678 - 60 thousand plants/ha (1.16 and 1.33 t/ha), VK 905 - 70 thousand plants/ha (1.50 t/ha). With the thickening of sowings of maternal lines by 10 thousand plants/ha, the yield of seeds from the sieve with a hole size of 2.5 х 20 mm on average decrease in VK 905 by 1.9%, VK 101, VK 678, and VA 760 - by 4.9-5.0%, and ED 765 - by 5.9%. With increasing the plant population from 40 to 70 thousand plants/ha, the oil content of seeds increased from 0.6% for VK 101 to 3.0% for VK 678, and on average for the maternal lines of hybrids - by 1.7%. We established the negative dependence of the head diameter, size of productive area of a head, thousand-seed weight, and number of filled seeds in a head on increase in the plant density. The increase of plant population by 10 thousand plants/ha resulted in decrease of a head diameter by 0.64-1.02 cm, productive area of a head by 14.4-27.2 cm2, thousand-seed weight by 1.4-3.5 g, a number of filled seeds in a head by 37125 seeds, depending on the maternal line of a hybrid.