Investigating drought tolerance in four Argania spinosa provenances through morpho-physio-biochemical traits

Drought stress significantly threatens plant ecosystems, particularly amid climate change. Understanding the mechanisms of plant resilience is essential for developing strategies to mitigate water scarcity effects on agroforestry. This study evaluated morphological, physiological and biochemical traits in Argania spinosa seedlings from four provenances (Berkane (BRK), Essaouira (ESS), Agadir (AGD) and Bouizakarne (BZK)) subjected to severe drought for three weeks. The results showed significant inter-provenance variation in the traits examined. Root dry biomass increased markedly across all provenances, with the highest increase observed in BZK (117.9%). Leaf water potential significantly decreased under drought stress, but relative water content (RWC) remained stable. Proline accumulation was significant in stressed seedlings, especially in ESS (163.4%), while total soluble sugars significantly increased only in BRK (26.6%). All provenances showed a significant reduction in chlorophyll a and b, except for BRK. Correlations among all studied traits varied significantly in both number and significance between drought stress and non-stress conditions. Canonical discriminant analysis revealed distinct separation among the provenances, indicating intra-species variability in drought responses. Key traits like dry biomass, collar diameter, basic leaf water potential, RWC and proline were identified as important indicators of drought tolerance, suggesting their utility in selecting the most resilient A. spinosa provenance.