PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Fruit load plays a decisive role in determining assimilate partitioning, reproductive efficiency, and seed physiological quality in fruit-bearing crops. In gynoecious parthenocarpic cucumber, excessive fruit retention may intensify sink competition and impair seed development, while insufficient fruit load may limit overall seed productivity. Current study evaluated the effects of fruit load on fruit traits, seed yield components, and seed quality attributes in the gynoecious parthenocarpic cucumber cultivar Pusa Parthenocarpic Cucumber-6 under net-house conditions during Kharif and Spring-summer seasons from 2019 to 2022. Three fruit load levels-two, three, and four fruits per plant-were imposed. Pooled ANOVA revealed that fruit load exerted highly significant effects (p < 0.001) on fruit size, number of seeds per fruit, seed yield per plant, speed of germination, seedling vigour indices, and electrical conductivity. Retention of two fruits per plant produced the largest fruits (≈800 g) and the highest seed number per fruit (145-146), indicating enhanced assimilate allocation per sink. However, maximum seed yield per plant was consistently achieved at three-fruit load (12.4-12.8 g), accompanied by faster germination (~59-60%) and superior seedling vigour (SVI-I ≈ 2840-2880). In contrast, four-fruit load significantly reduced fruit size, seed number (93-95), germination speed, and seedling vigour, and enhanced electrical conductivity (~77-78 µS m⁻¹), reflecting compromised membrane integrity. The multi-season data of current study enhances the robustness and reproducibility of the findings and strengthens their physiological relevance. Overall, maintaining three fruits per plant provides an optimal balance between seed yield and seed physiological quality, representing a scientifically grounded and practically viable strategy for high-quality seed production in gynoecious parthenocarpic cucumber under protected cultivation. Given the year-round production potential and high value of parthenocarpic cucumber in protected environments, adoption of optimized fruit load management can improve on-farm seed production efficiency, reduce dependence on costly commercial seed, and enhance profitability and accessibility for growers.