Dependence of the amount of certified seeds of maternal lines of sunflower hybrids on the plant density

In 2017-2020, on leached black soils in the central climatic zone of the Krasnodar region we studied the patterns of amount of a fraction of certified seeds (amount of physically clean seeds from a sieve with holes of size 2.5 x 20 mm) of the early maturing inbreds - the maternal forms of sunflower hybrids VK 101, VK 678, VK 905, VA 760 and ED 765 bred at the V.S. Pustovoit All-Russian Research Institute of Oil Crops depending on the plant density of 40, 50, 60 and 70 thousand plants/ha. We established the negative dependence of the amount of a fraction of certified seeds on the plant density. On average for 2017-2020, the maximum yield of such seeds was obtained when growing the studied maternal lines with plant density of 40 thousand plants/ha: 95 % in VK 905, 88 % in VK 678, and 76-79 % in VA 760, VK 101, and ED 765. With the increasing plat population from 40 to 70 thousand plants/ha, after each 10 thousand plants/ha on average, the amount of a fraction of certified seeds decreased by 1.9 % in VK 905, by 4.9-5.9 in VK 101, VK 678, VA 760, and by 5.9 % in ED 765; the number of a fraction of certified seeds per head decreased by 37 in VK 95 to 125 pieces in VK 101. The highest weight yield and number of a fraction of certified seeds per 1.0 m2 of sowing area of the maternal lines was obtained when growing VK 101 with a plant density of 50 thousand plants/ha, VK 678, VA 760, and ED 765 - 60 thousand plants/ha, VK 905 - 70 thousand plants/ha. We established the negative dependence of thousand-seed weight on the plant density; as the density increased by 10 thousand plants/ha, 1000-seed weight decreased by 1.4 g in VK 760, by 2.2 g in VK 101, by 3.1-3.2 in ED 765 and VK 678, and by 3.5 g in VK 905.