Genotype-Specific Synergy Between Arbuscular Mycorrhizal Fungi and Olive Cultivars Enhances Drought Resilience in China’s Olive Belt

To address severe seasonal drought affecting over 60% of China’s olive-growing regions, this study evaluates whether arbuscular mycorrhizal fungi (AMF) can enhance drought tolerance in elite olive cultivars (Arbequina and Koroneiki) under simulated arid conditions. A controlled pot experiment inoculated seedlings with two AMF strains (Rhizophagus intraradices [AMF1], Funneliformis mosseae [AMF2]) under full irrigation or a 32-day water deficit. Biomass, root colonization, photosynthesis, PSII efficiency, osmolytes, antioxidants, and lipid peroxidation were measured. Data were analyzed via two-way ANOVA, Pearson’s correlation, and principal component analysis (PCA). Under optimal hydration, both AMF strains colonized >60% of roots, significantly increasing Arbequina biomass by 25–35% (p < 0.05) and Koroneiki biomass. Drought reversed benefits in Arbequina but triggered resilience: AMF1 restored photosynthesis (18%), Fv/Fm (37%), and water potential (18%) (p < 0.05) while reducing lipid peroxidation (79%) (p < 0.01). In Koroneiki, AMF2 restored Ψw to 47% of pre-irrigation levels and increased root volume (137%), PSII efficiency (43%), osmolytes (100%), and carotenoids (28%) (p < 0.01). PCA ranked Arbequina–drought–AMF1 as the most resilient combination. Pairing AMF strains with specific cultivars offers a scalable, chemical-free strategy to stabilize olive productivity in southwest China’s aridifying climate, advancing climate-smart agriculture for drought-prone regions.