P ollination is an important phase in the production of many fruits and vegetables. In modern agriculture, with competitive markets for quality fruits, vegetables and hybrid seeds, the role of pollination can influence economic profit. Most fruit trees in Israel and the United States are pollinated by insects that collect pollen from the anthers of flowers and transfer them to stigmas. Sometimes, poor pollination occurs because of unsuitable climatic and ecological conditions or incompatibility between the pollinators and the plant flower. Several researchers (Ish-Am and Eisikowitch, 1991) have reported that a cloud of pollen rises from the flower anthers and is attracted to bees that hover above the flower. This observation led to a hypothesis that the bee is electrically charged when flying and flapping its wings (Erickson, 1975; Y’eskov, 1976). Thus, when a charged bee approaches a flower, it induces an electric charge on the flower that in turn generates electrostatic forces, which cause or help the detachment of the pollen grains (Gan-Mor et al., 1995). Recently developed technologies for the deposition of small particles utilize electrostatic forces that are widely used in copying machines, car painting and in pesticide spraying. Previous works show that electrostatic spraying provides better target coverage, material savings, and decreased drift (Gan-Mor and Law, 1992; Dante and Gupta, 1991; Lake, 1988; Law and Bowen, 1975; Law, 1978). Artificial pollination is practiced on several commercial crops such as dates, apples, and more. In kiwifruits, artificial pollination, performed as hand pollination, improved yield quantity and quality (Gonzalez et al., 1998). In almond orchards, devices for dispensing pollen are attached to the hive entrances so that the outgoing bees are covered with pollen grains on their way out (Free, 1993). Artificial pollination is also practiced in hybrid seed production. The cost of pollen is very high (Gan-Mor et al., 1995) and, therefore, improving the efficiency of this process could be beneficial. The objectives of the work presented here were: (1) to analytically investigate electrostatic fields and forces during the approach of a charged cloud of pollen to a flower; (2) to validate the model experimentally; and (3) to use the findings to design and test a pollinating system in an orchard. METHOD AND MATERIALS The work was comprised of four parts: (1) development of a finite-element model of a charged cloud of pollen approaching a date flower; (2) simulation of a pollen grain trajectory; (3) laboratory experimentation on the deposition of the charged pollen cloud on a date flower; (4) field experiments on electrostatic pollination of dates (Phoenix dactylifera L.). FINITE-ELEMENT MODEL A 3-D finite-element model of the flower and pollen cloud, shown in figure 1, was constructed using the ANSYS 5.1 program on an ALFA - DEC 3000 computer (Digital Equipment Corp. Inc.). MODELING AND EXPERIMENT ANALYSIS OF ELECTROSTATIC DATE POLLINATION A. Bechar, I. Shmulevich, D. Eisikowitch, Y. Vaknin, B. Ronen, S. Gan-Mor ABSTRACT. Artificial pollination can influence economic profit in modern agriculture and competitive markets for quality fruits, vegetables and hybrid seeds, especially where climatic and ecological conditions are unfavorable. Technologies for electrostatic deposition of small particles were modified for flower pollination. The electric field in a system comprised of a charged cloud approaching a grounded flower was investigated with a 3-D finite element model. A simulation based on a finite element model was created and the pollen grain trajectories, which initiated from the cloud and ended on the flower, were calculated. An experimental device for electrostatic pollination was developed and tested in the laboratory and then under field conditions. Both model and laboratory results showed increased pollen density on the stigma, as compared to the flower envelope. Field experiments on dates (Phoenix dactylifera L.) showed that electrostatic pollination doubled the yield. The work demonstrated the advantages of electrostatic pollination and the possibilities for developing this technology. Keywords. Pollination, Electrostatic, Artificial pollination, Finite element, Date, Agriculture. Article has been reviewed and approved for publication by the Power & Machinery Division of ASAE. Presented as ASAE Paper No. 96-0184. The authors are Avital Bechar, Researcher, Institute of Agricultural Engineering, Agricultural Research Organization, Bet Dagan 50250, Israel; Itzhak Shmulevich, ASAE Member Engineer, Associate Professor, Faculty of Agricultural Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel; Dan Eisikowitch, Professor, and Yiftach Vaknin, Graduate Student, Dept. of Botany, Tel Aviv University, Tel Aviv 69978, Israel; Beni Ronen, Technician, and Samuel Gan-Mor, ASAE Member Engineer, Senior Scientist, Institute of Agricultural Engineering, Agricultural Research Organization, Bet Dagan 50250, Israel. Corresponding author: Avital Bechar, Institute of Agricultural Engineering, Agricultural Research Organization, PO Box 6, Bet Dagan 50250 Israel; voice: 972-3-9683753; fax: 972-3-9604704; e-mail: avital@agri.gov.il. Transactions of the ASAE © 1999 American Society of Agricultural Engineers 0001-2351 / 99 / 4206-1511 1511 VOL. 42(6): 1511-1516