Optimizing Hybrid Seed Yield in Sunflower (Helianthus annuus L.) Hybrid KBSH-78 Through Flowering Synchronization and Nitrogen Management

Abstract

Flowering synchronisation between parental lines is a critical prerequisite for successful hybrid seed production in sunflower (Helianthus annuus L.), as efficient pollination and seed set largely depend on the overlap of flowering periods. The present investigation was conducted at the Regional Agricultural Research Station, Vijayapura, Karnataka, India, to evaluate the effects of staggered sowing of the male parent and nitrogen application to the female parent on hybrid seed yield and its contributing traits in sunflower hybrid KBSH-78. The experiment was laid out in a factorial randomised block design comprising four staggered sowing treatments of the male parent and two nitrogen management practices for the female parent. Significant differences were observed among the treatments for all yield and seed quality parameters. Delaying the sowing of the male parent by six days significantly increased head diameter (15.12 cm), head weight (84.34 g), seed weight per head (41.54 g), 100-seed weight (6.49 g), seed set (79.23 %), seed yield per plot (800.65 g), and seed yield (926 kg ha⁻¹), while reducing chaffiness (24.01 %) and hull content (25.54 %). Among the nitrogen treatments, soil application of 25 kg N ha⁻¹ at the button stage of the female parent significantly outperformed the 2 % foliar nitrogen spray. The interaction treatment comprising sowing of the male parent six days later, together with soil application of 25 kg N ha⁻¹, recorded the highest seed yield (945 kg ha⁻¹), the maximum seed set (80.11 %), and superior yield-contributing traits. Improved flowering synchronisation ensured continuous pollen availability during the receptive period of the female parent, resulting in enhanced pollination efficiency, fertilisation, seed filling, and ultimately higher hybrid seed yield. The study demonstrates that delaying the sowing of the male parent by six days, in combination with soil application of 25 kg N ha⁻¹ at the button stage, is an effective agronomic strategy for maximising hybrid seed production in sunflower.