Clonal selection of Argan trees (Argania spinosa L. Skeels) in the Admin forest, Agadir, Southwestern Morocco

Abstract

The Argan (Argania spinosa L. Skeels) is a multipurpose tree endemic to Morocco. As such it plays an important economic role. However, these naturally occurring trees present a huge variability in terms of biomass production and fruit yield. The actual tendency in Morocco is to promote Argan tree planting for oil production. Nevertheless, for this purpose it would be more rewarding to propagate trees with desirable characteristics such as fruit and oil yield, nut crushing easiness and low rate of yield alternation from one year to another. The objective of the present work is to select performing specimens among a population of old trees (over 50 years old) and young ones (7 years) located in a 100 ha land in Admin forest (Agadir), Morocco. The old population pool is composed of 1000 trees and the young one comprises 9000 trees. Selection was based on several criteria but yield and alternation rate were the most important. Climate parameters have been also taken into consideration. Correlation between rainfall, strong winds and Chergui (a dry and hot wind coming from south and southeast) showed that climatic conditions affect Argan productivity. Over the 3 years that this study has lasted, and using ANOVA (analysis of variance) and PCA (principal component analysis) analyses, it was possible to distinguish 5 old and 5 young trees for their superiority in terms of almond and oil yield. These performing old and young trees are labeled in the field and geographically localized using a GPS for latitude and longitude coordinates. Further work is required to use vegetative propagation to ensure that the desirable characters set herein are maintained in daughter plants.