Aloni, D.D., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Hazon, H., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Edom, U., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Sendelham, D., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Karp, C., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Pumeranc, R., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel
Cohen, Y., Department of Fruit Tree, Agriculture Research Organization, Volcani Research Center, Bet Dagan 50250, Israel

Being monocotyledonous trees, palms are unique in their morphology and growth patterns. Date palm trees have a single trunk that can reach up to 25 m. The leaves, inflorescences and consequently, the fruit bunches develop on the crown, at the top of the very tall trunk, from a single meristem: the "palm heart". Thus, it is impossible to prune the trees. The developing leaves and inflorescences, generated deep within the trunk, are inaccessible for direct bioregulator treatments. Date palm cultivation requires workers to climb the tall trees to collect pollen, pollinate flowers, thin fruit bunches, harvest fruit and perform various other horticultural activities. Climbing the trees is laborious, expensive and extremely dangerous. We followed the effects of two growth regulators, paclobutrazol and uniconazole-P, on the vegetative growth of young and mature date palms. Both growth regulators restrained trunk growth, reducing the vertical height contributed to the trunk by each generated leaf. The treatment constrained the elongation rate of the leaves, and reduced the leaf length, but did not reduce fruit quality or yield. The results suggest the future use of growth retardants to reduce trunk height, enabling less expensive, safer and more efficient management of palm trees.