Influence of Genotype and Planting Date on Seed Yield and it’s Components in Sunflower (Helianthus annuus L.)

Two key factors, sunflower genotypes and planting dates, significantly impact sunflower seed production. This study examines the relationship between sunflower yield and its components. (split-plot design) was used with three replications across two seasons at the Qlyasan location in 2024. The subplot treatments included planting dates in spring (March 15, April 4, and 24) and summer (July 1, 21, and August 10). The main plot treatments consisted of four sunflower genotypes (BAROLO RO, VELKO, DEA, and LOCAL). Results revealed notable differences among genotypes in seed yield, with the BAROLO RO genotype producing the highest seed yield (3094.573 and 3237.292 kg ha-1) in both seasons. For planting dates, April 4 and July 1 yielded the highest seed yield (2939.483 kg ha-1 and 2607.640 kg ha-1) in spring and summer, respectively. The results revealed a positive and highly significant relationship between seed yield and full seed weight (r = 0.930) during the spring season. The correlation between seed yield and other characters, such as stem diameter, head diameter, head weight, and full seed weight, showed a highly significant and positive correlation (r = 0.857, r = 0.962, r = 0.955, and r = 0.967) in the summer season. Path coefficient analysis helps break down the correlation into direct and indirect effects. The highest positive direct effect was (1.485; 0.441) for 1000-seed weight, and head weight in spring and summer. The highest indirect effect was 1.492 for head diameter, mediated by the number of full seeds plant-1, and 0.416 for full seed weight, as indicated by head weight during the spring and summer seasons. Results suggest that selecting based on head diameter, head weight, 1000-seed weight, full-seed weight, and the number of full seeds per plant will be more effective in improving yield.