Integrating plant growth regulators (PGRs) and nano-nutrients to alleviate fruit drop and enhance reproductive efficiency in ber cv. apple ber

Ber (Ziziphus mauritiana L.) is a significant fruit crop grown in dry and semi arid areas. However, low fruit retention and significant fruit drop frequently limit production, thereby lowering output in field settings. Therefore, increasing ber output requires the development of efficient agronomic techniques to enhance reproductive performance.The current study set out to assess how melatonin and nano-calcium nitrate together affected apple ber yield, flowering behavior, fruit retention, and fruit drop. The experiment was designed using a Factorial randomized block design (FRBD) with three repetitions, each consisting of 25 combinations of treatments with plant growth regulators (PGRs) and nano-nutrients applied as foliar sprays. The data were recorded as days to flowering, fruit set, fruit drop, fruit retention, number of fruits per plant, and yield. Their interaction [melatonin (A5) 15 ppm + nano calcium nitrate (B5) 0.05%] resulted in the highest fruit retention (29.0%), highest fruit set (87.99%), average number of fruits (1561.0), and average fruit yield (54.23 kg) compared to the control. These interactions (A5B5) also have the earliest days to start flowering (18 days) and the lowest fruit drop (71.0 %) compared to the control. These results highlight the potential of melatonin and nano-calcium nitrate as an effective agronomic strategy to enhance reproductive performance and yield in ber cultivation, contributing to sustainable horticultural practices and future research on nano-enabled PGRs.