Effect of soil drought stress on leaf water status and photosynthetic apparatus in argan seedlings (Argania spinosa)

Abstract Argan tree growth and production are both affected by drought stress, which is recognized as a critical and serious environmental issue worldwide. This study aims to examine the effect of a multi-species consortium of arbuscular mycorrhizal fungi (AMF) “Rhizargan consortium”, on the leaf water status and photosynthesis in drought-stressed argan seedlings. The performances of Rhizargan consortium were compared to those of a single pure commercialized strain of Rhizophagus irregularis. Seedlings of two argan tree ecotypes were subjected to three water regimes: 30, 60, and 100% field capacity (FC). After twelve months of drought stress, mycorrhizal argan seedlings showed a significant increase in leaf water potential, stomatal conductance, and maximum efficiency of PSII (Fm/Fv) than those without mycorrhiza inoculation. Moreover, AMF inoculation led to significant leaf accumulation of chlorophyll and carotenoid upon drought imposition. Nonetheless, severe drought stress (30% FC) decreased these physiological/photochemical attributes as well as both frequency and intensity of mycorrhization, but to a lesser extent in the argan seedlings inoculated with “Rhizargan consortium”. This study contributes to advances in the knowledge of the indigenous Rhizargan consortium’s ability to induce drought tolerance in argan trees.