The argan tree (Argania spinosa) in Morocco: Propagation by seeds, cuttings and in-vitro techniques

Abstract

In South-western Morocco, the argan tree (Argania spinosa) is basis of a traditional agroforestry system. However, this system is no longer at equilibrium and there is an urgent need to renovate it. The natural reproduction of the tree has become difficult, and most attempts of artificial regeneration have failed. We have assessed three different propagation methods: seedlings, cuttings, and in-vitro micro-propagation. Our experiments, involving several seed collections, showed that germination occurred easily when using young (< 12 months) and large seeds (nut weight > 3 g). Nuts with thin walls germinated better than nuts with thicker walls. Sterilization prevented microbial contamination and improved germination. Vegetative propagation of the argan tree by cuttings was tried using lignified cuttings collected from adult trees or young stems from managed stockplants (three years old). Rooting rate seems to be dependent on genotype, and the best results were obtained from young stems sterilized to avoid fungal contamination. The success of in-vitro micro-propagation is also highly genotype-dependant. We developed a modified medium enabling up to 80-95% rooting rate for some clones. However, other clones were still recalcitrant. Whatever the propagation method used, special attention must be paid to the architecture and growth of the root system.