Unveiling Biochemical Drivers of Bee Pollination in Short- Day Indian Onion (Allium cepa L.) Varieties

Pollination is crucial for onion ( Allium cepa L.) seed production, and honey bees ( Apis mellifera ) are the major pollinators. The biochemical content of pollen and nectar has a substantial impact on pollinator foraging behavior and seed yield. However, there has been little investigation into biochemical traits of short-day Indian onion cultivars that influence bee visitation and pollination effectiveness. This study looks at the biochemical characteristics of pollen and nectar in short-day Indian onion varities to unveil their role in bee pollination. The study investigates nectar sugar composition, amino acid profiles, total phenols, and antioxidant properties, and their relation with bee pollination in onion. Field experiments were carried out to assess the floral visitors, while biochemical composition of nectar and pollen were also analyzed using LC-MS/MS, and spectrophotometry. The results revealed that, among the onion cultivars, ‘Bhima Super’ had best bee attracting biochemical traits, with high protein (391.8 mg/g), flavonoids (855.3 mg/g), and antioxidant activity (3.6 µg/g) in its pollen. Besides, the nectar of B. super was also rich in protein (83.6 mg/g), flavonoids (9.7 mg/g), and sugars (40.53 mg/g). In contrast, the onion cultivar ‘Bhima Shweta’ revealed the less amount of this biochemical content. Foraging trend of bees revealed that ‘Bhima Super’ had the highest foraging rate (14.151 visits/min) and foraging speed (6.703 flowers/min), correlating with its biochemical traits. Cultivar,‘Bhima Shakti’ also showed a positive correlation between nectar sugar (43.8%), antioxidants (r = 0.682), and bee activity, with its pollen contains rich in iron (0.520 µg/g), zinc (0.75 µg/g), and manganese (0.37 µg/g). These findings confirm strong correlations between pollen and nectar biochemistry and bee foraging. The study insights into pollen and nectar of short day India onion cultivars, providing new avenue for improving managed pollination strategies in onion seed production.