Improvement of agricultural practices in the production of high-quality seeds of sunflower line at the multiplication plot

The research was conducted in 2024 on a multiplication plot of the maternal form VK101sur A, and in 2025, when the produced seed material was processed after harvest with simultaneous cleaning, sorting, and evaluation of the field germination of three selected seed fractions (large, medium, and small). The experiments were carried out on the multiplication plot at the farm “Urupskoye” (Novokubansky district, Krasnodar region), while processing, fractionation, and field germination evaluation were performed at the V. S. Pustovoit AllRussian Research Institute of Oil Crops (Krasnodar). The aim of the research was to study the effects of five agricultural practices (1 – K – control, 2 – U – fertilizer application, 3 – U + KhZR – application of fertilizers together with chemical plant protection products against diseases, 4 – KhZR – application of chemical plant protection products against diseases, 5 – BZR – application of biological plant protection products against diseases) on the yield and sowing qualities of seed fractions of the sunflower line VK101sur A, produced on the multiplication plot. Three seed fractions with different ranges of variation in yield value were identified for the sunflower multiplication plot variants: large (size bigger than 3.6 mm, ranging from 18.1% to 27.4%); medium (size between 3.6 and 2.8 mm, ranging from 51.5% to 59.3%); and small (size between 2.8 and 2.2 mm, ranging from 19.6% to 25.8%). The largest thousandseed weight was observed in the large fraction (70.7 g) in variant 4 – KhZR, the medium fraction (54.9 g) in variant 3 – U + KhZR, and the small fraction (39.4 g) in variant 5 – BZR. Fractionation reduced the variation interval of this indicator from 4.6 g to 1.4– 2.1 g. Increasing the seeding rate from 65 to 75 thousand pcs/ha in the multiplication plot reduced the weight by 1.2 g in the large fraction and by 1.1 g in the medium fraction. The highest field germination was observed in variants 4 – KhZR for the large and medium fractions (91%) and in variant 2 – U and the control for the small fraction (90%).