Phenology, breeding system and fruit development of argan [Argania spinosa, Sapotaceae] cultivated in Israel

Argan (Argania spinosa) is an evergreen tree native to southwestern Morocco appreciated for its edible, high nutritional oil, extracted from the kernels of the drupe-like fruit. Aspects of its reproductive biology were studied with the aim to domesticate the tree as an oil crop. Flowering of fertigated trees cultivated in the Negev Highlands of Israel was confined to the spring months. The flowers were protogynous. Results of different pollination treatments showed that a pollen vector was necessary for pollination and that fruit set was significantly higher in cross and open pollination (7-9%) than in self pollination (0.5%). The lower fruit set obtained in self pollination was related to postzygotic discrimination. Pollen transfer by wind was restricted to short distances. Flies, mainly of the family Calliphoridae, visited the flowers and were found to be covered with argan pollen. Fruits ripened nine months after anthesis, exhibiting bisigmoidal growth curve.