Traditional pollination of date palms is a time-consuming and labor-intensive process. Hence, the objectives of this study were 1) to develop a rapid, efficient, and low-cost pollination method that results in an acceptable level of fruit set (FS) with smaller amount of pollen grains, and labor costs using a platform-mounted robotic (drone) supplemented with water-suspended pollen grains, and 2) to investigate the effect of this method on date palm FS percentage, pollination efficiency (PE), fruit retention, total yield, and fruit quality. Date palm cultivars Barhi, Lulu, and Khesab were pollinated using traditional hand pollination (HP), spray pollination (HS), and drone pollination (DS) with water-suspended pollen grains (3 g/L). The results revealed that DS had a significantly lower FS percentage than the HP and HS methods in the Lulu and Khesab cultivars, but the difference was not statistically significant in Barhi cultivar. Fruit PE was unaffected by any of the pollination methods in Barhi and Lulu cultivars, but in the Khesab cultivar, DS pollination had lower PE (0.81) than HS (0.94) and HP (0.99) methods. DS had significantly lower levels of fruit retention and bunch weight than other methods. DS significantly improved fruit physical quality at harvest in all cultivars compared with HP and HS methods. Nevertheless, fruit color, firmness, total soluble solids (TSS) %, acidity, pH, and vitamin C level were unaffected by any of the pollination methods. Although the DS method produced lower FS percentage and bunch weight, the obtained FS percentages were within the commercially acceptable range for all cultivars. To the best of our knowledge, this is the first field study to indicate the possibility of pollinating date palm using drones with water-suspended pollen grain. To validate the commercial application, more research is needed to justify the optimum time and duration of application, which may vary according to cultivar and region.
