Integrated nutrient management and deficit irrigation: Enhancing wheat resilience and productivity under drought stress

Abstract Water scarcity and drought stress pose significant challenges to wheat ( Triticum aestivum L. ‘Chamran‐2’) production, particularly in arid and semiarid regions. This study, conducted during 2022–2024 in Fars Province, Iran, evaluated integrated nutrient management (INM) strategies under deficit irrigation (DI). A split‐plot arrangement within a randomized complete block design was implemented, with four replications. Main plots included full irrigation (FI) and DI applied at noncritical growth stages (tillering, stem elongation, and post‐pollination), while subplots comprised four INM treatments: optimal nutrition (control) (ON), biofertilizers with humic acid (BH), foliar sprays of fulvic acid, potassium silicate, and amino acids (F), and a combined F+BH treatment. DI reduced nutrient uptake, photosynthesis, and grain quality, but INM, especially F+BH, mitigated these effects by improving nutrient translocation, osmotic adjustment, and oxidative stress tolerance. The combined F+BH treatment increased chlorophyll a and b by 8.6%, photosynthesis by 7.7%, and stomatal conductance by 13.8%, while reducing proline by 26.2%, indicating stress alleviation. Under DI+F+BH, water use efficiency (WUE) improved by 53.3% compared to FI+ON. Principal component analysis identified calcium, boron, and zinc as key contributors to metabolic efficiency and drought resilience. The DI+F+BH treatment effectively sustained productivity, enhancing physiological traits, grain protein content, and economic returns. DI, combined with F+BH, demonstrated superior WUE and profitability, emphasizing its value as a water‐saving strategy in arid regions.