Comparative analysis of natural and supplemental pollination through pollen suspension on neem (Azadirachta indica A. Juss) fruit set and morphological characteristics

A supplemental pollination system is crucial when natural pollinators are unavailable or unreliable, as alternative management strategies are necessary to ensure adequate pollination in pollination-dependent trees. Supplemental pollination controls pollen quantity, timing and frequency, resulting in increased yields, improved fruit quality and reduced fruit abortion. In a comparative study of pollination methods, hand pollination using a brush yielded the highest fertilization rate (5.54 ± 0.03 %), followed by a 1 % pollen mixture with 0.2 M basal sucrose solution and 0.01 % Gelrite (5.09 ± 0.21 %). A mixture of 1 % pollen grains with 10 ppm boric acid produced a fertilization rate of 4.75 ± 0.14 %. Hand pollination resulted in the highest fruit production, with 313 ± 43 fruits, while the sucrose solution treatment yielded 287 ± 8 fruits and the boric acid treatment produced 273 ± 12 fruits. In contrast, closed pollination recorded the lowest yield, with only 14 ± 7 fruits. Morphological assessments of neem fruits and seeds revealed that the boric acid treatment (1 % pollen grains and 10 ppm boric acid) achieved the best results, producing the most significant fruits and seeds. Conversely, the sucrose solution and Gelrite treatment showed the lowest values for fruit weight and fruit-to-seed ratio, highlighting the effectiveness of boric acid in enhancing neem fruit and seed morphology.