Enhancing Sesame ( <i>Sesamum indicum</i> L.) Yield and Drought Tolerance through Reduced Phosphorus Fertilizer Combined with <i>Funneliformis mosseae</i> and Humic Acid Under Varying Irrigation Regimes

Sesame ( Sesamum indicum L.), a drought‐tolerant oilseed, faces yield constraints under water scarcity in arid regions. Phosphorus (P) fertilizers, though beneficial, pose environmental and availability challenges, necessitating sustainable alternatives. A 2‐year field experiment in southern Iran used a split‐plot design to evaluate integrated P management under three irrigation regimes: normal (I1, 40% soil moisture depletion), moderate drought (I2, 60% depletion), and severe drought (I3, 80% depletion) as main plots, with seven fertilizer treatments (no fertilizer [F1], 100% P [F2], arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae [F3], humic acid [F4], 50% P + AMF [F5], 50% P + humic acid [F6], and 50% P + AMF + humic acid [F7]) as subplots. Drought reduced seed yield, oil yield, and physiological traits, but combined treatments (F5, F6, F7) enhanced these compared to individual applications and control. Notably, F5 increased seed yield by 62% and oil yield by 85.5% versus F1, with no differences among F5, F6, F7. These treatments mitigated drought by improving photosynthetic pigments, antioxidant activity, and osmolyte levels. No irrigation–fertilizer interactions were observed, indicating consistent benefits. Integrating 50% P with AMF and/or humic acid enhances sesame yield and drought resilience, reducing reliance on nonrenewable P for sustainable arid‐region agriculture.