Abstract

The argan tree, is a member of the tropical family Sapotaceae, is an endemic of south western Morocco appreciated for its edible, high nutritional oil, extracted from the kernels of the fruit. The total number of fruiting branches (F), with one (F1), two (F2), three (F3) and four or more fruits (F4) in ten units of four different types of branches were observed for three consecutive seasons in three localities in south west Morocco. The twigs of the season and those less than two seasons have not fruited even if they have flourished. In contrast, the twigs more than two seasons and the main branches bear fruits. Fruit production in argan tree is largely dependent on temperatures and rainfalls during the cycle of flowering and fruiting which covers about 16 months. Prolonged drought during the flowering season is manifested by a significant reduction of the fruiting branches and number of fruits on twigs during the fruit ripening season. Contribution in the phenotypic variance of the climatic season and tree x environment interaction were very significant (18.5 and 52.9%). Broad sense heritabilities were low and ranged between 0 and 14.4%. Differentiation between the three populations for the fruiting branches is not established. However, most trees from Argana and Ait Melloul were most fruit bearing. Argan is especially valued by its fruit and oil, this work shows the existence of significant potential to improve fruiting in this species, which is in the wild state, by the choice of plus genotypes and the optimization of fruit production techniques for the argan domestication as a fruit tree for oil production.

Key words: Argania spinosa, diversity, fruit, fruiting branches, repeatability, multivariate analysis.