Drought severely limits avocado production, necessitating sustainable resilience strategies. This study investigated the effects of arbuscular mycorrhizal fungi (AMF) inoculation (Gigaspora and Rhizophagus spp.) on the drought tolerance of two avocado races (‘Mexicana’ and ‘Guatemalan’) under controlled shade house conditions. A factorial experiment with four moisture-withholding interval (daily, 7, 14, and 21 days) and AMF treatments were conducted. AMF inoculation significantly enhanced seedling morpho-physiology under all stress levels. Inoculated plants exhibited a 12% increase in plant height and a 10% increase in internode length compared to noninoculated controls. Leaf area, fresh weight, and dry weight improved by 32.5–43.9%, 24.2e–29.9%, and 20–26.6%, respectively, under drought. Root system development was profoundly enhanced, with root number and taproot length increasing by 26–38.5%, and root biomass surging by 46.2% (fresh) and 38.8% (dry) under the severest 21-day stress. Physiologically, AMF increased stomatal conductance by 23–41% and total chlorophyll content by up to 24.4%, supporting higher photosynthetic rates. The ‘Mexicana’ race consistently outperformed ‘Guatemalan,’ showing superior leaf area, biomass, and water use efficiency under stress. AMF colonization rates were highest (67.9%) under daily watering and declined (39.7%) with severe drought. We conclude that AMF symbiosis significantly mitigates drought impairment in avocado seedlings, with ‘Mexicana’ demonstrating greater inherent tolerance. This synergy offers a viable strategy for enhancing resilience in water-limited avocado cultivation.
Mycorrhizal symbiosis; race variation; seedling physiology; water-stress mitigation