Effect of seed treatment by a bioformulation based on arbuscular mycorrhizal fungi (AMF) on the growth of argan plants (Argania spinosa (L.) Skeels)

The treatment of argan tree seeds with a composite inoculum of arbuscular mycorrhizal fungi (AMF), native to the rhizosphere of argan trees grown in different regions of Morocco, resulted in the mycorrhization of the roots of plants after germination of treated seeds coupled with a positive effect on the growth of argan plants. Thus, after 12 months of cultivation in a greenhouse, the root and aerial masses of the plants resulting from the treated seeds showed a significant increase in growth parameters. The fresh root and vegetative weights reached 2 and 6.86 g compared to the control plants: 0.21 g and 1.7 g and the length of roots was in the order of 47.8 cm compared to that of control plants (15.1 cm). In addition, the height of the aerial parts of argan plants attained 65.2 cm threefold value than that obtained in control plants (20.2 cm). The average diameter of collar part in treated plants relative to untreated ones was 0.98/0.1 cm, that, of formed twigs number was 2/1. Similarly, the obtained result indicated that the harvested plants were mycorrhizated, and exhibited a frequency mycorrhization of 100 % and intensity of 25% while vesicular and arbuscular content were in the order of 2.5 and 10.5% respectively. No mycorrhization signs occurred at the roots level of the plants from the untreated seeds. Applying this AMF-based bioformulation through seed inoculation has provided a promising result by improving argan plant growth while accelerating plant growing.