INFLUENCE OF FRACTIONAL COMPOSITION OF SUNFLOWER HEAP ON SOWING AND TECHNOLOGICAL QUALITIES OF SEEDS

<jats:p>Sunflower seed quality is a critical factor determining yield and profitability. The effectiveness of seed formation directly depends on post-harvest processing, a key step of which is grain heap fractionation, which allows for the separation of the heterogeneous mass into fractions based on size and condition, as well as the removal of damaged samples. The objective of this study was to comprehensively assess the impact of sunflower heap fractional composition on processing and sowing qualities. Laboratory studies were conducted on Tunka sunflower seeds. A U1-ERL-2-1 laboratory sifter was used to simulate the separation process. The feedstock was separated into fractions using calibrated sieves with aperture diameters ranging from 6.5 to 4.0 mm in 0.5 mm increments. For each fraction obtained, the yield as a percentage of the total mass, the average 1,000-seed mass, the content of damaged, hulled, and crushed caryopses, as well as key sowing parameters—germination energy and laboratory germination—were determined. The experimental results revealed a strong correlation between seed size and quality. It was found that the largest fractions, separated on sieves with 6.0 and 6.5 mm mesh diameters, had higher 1,000-seed masses, ranging from 56.4 to 68.6 g, and demonstrated the highest sowing quality: germination energy exceeded 97%, and laboratory germination was 98%. At the same time, they had a minimal content of damaged caryopses, not exceeding 11%. Fine fractions obtained on 4.0 and 4.5 mm screens were characterized by low specific gravity, an increased content of damaged and hulled seeds (23.6%), and significantly reduced germination rates. These data clearly demonstrate that effective fractionation is a prerequisite for obtaining the highest-quality seed material that meets current state standards.</jats:p>