Improving pollination of almond (Amygdalus communis L., Rosaceae) using electrostatic techniques

Supplementary pollination of almond using electrostatic techniques was tested in a three year study (1996-1998) in Northern Israel. We used an electrostatic pollination device and tested its effects on fruitlet set, fruit set, yield weight and nut weight. We also tested its ability to pollinate flowers on the tree from the distal to the proximal part of the branches. We found that when individual branches were pollinated, fruitlet set was in accordance with the expected deposition rate of pollen grains on the stigma: electrostatic + open pollination > non-electrostatic + open pollination > open pollination > electrostatic pollination > non-electrostatic pollination > spontaneous self pollination. Fruit set results showed the same pattern but were not as precise. Electrostatic pollination of individual trees resulted in an insignificant increase in pollen germinability on the stigma. The highest germinability was on the distal part of the branch and the lowest was on the proximal part of the branch, in all pollination treatments. Electrostatic pollination increased yield as compared with non-electrostatic and open pollination. Nut weight, however, decreased slightly with increased yield. We suggest that electrostatic pollination can be an important method for pollen supplementation in almond orchards when honeybee pollination is insufficient and when the trees can withstand the added portion of nuts, resulting from improved pollination.