Integrated application of foliar biostimulants and biofertilizers improves wheat resilience, nutrient uptake, and yield under deficit irrigation in semi-arid regions

Wheat production in semi-arid regions faces increasing challenges from drought, heat, and salinity stress, intensified by climate change. This study aimed to evaluate the effects of integrated nutrient management (INM) strategies combined with different irrigation regimes on the physiological performance, nutrient dynamics, yield, and water use efficiency (WUE) of wheat ( Triticum aestivum L. cv. Sirvan). Over two growing seasons (2022–2024), field experiments were conducted under two irrigation regimes: full irrigation (FI) and deficit irrigation (DI). INM treatments included foliar biostimulants (F: fulvic acid, seaweed extract, potassium silicate, amino acids), biofertilizer with humic acid (BH), and their combination (F+BH). Physiological parameters, nutrient concentrations, yield components, and WUE were measured. Principal component analysis (PCA) was used to identify key determinants of yield. DI reduced photosynthesis (15.9 %) and macronutrient uptake, while increasing grain micronutrient levels (Fe, Zn, Mn). The F+BH treatment significantly enhanced flag leaf nutrient concentrations (e.g., 20.6 % P, 17.5 % Zn), improved photosynthetic rate (60 %), and maintained plant water status under both FI and DI. FI+F+BH achieved the highest grain yield (5400 kg ha⁻¹), while DI+F+BH produced 5000 kg ha⁻¹ using 36 % less water, improving WUE by 41 % and achieving the highest benefit-cost ratio (1.73). Integrating biostimulants and biofertilizers with deficit irrigation enhances wheat resilience, nutrient uptake, photosynthetic capacity, and economic efficiency. These strategies offer a sustainable approach for optimizing productivity and resource use in semi-arid, water-limited environments. • F+BH treatment improved wheat nutrient uptake and grain quality under drought stress. • Deficit irrigation with F+BH increased water use efficiency by over 40 %. • F+BH enhanced photosynthesis, RWC, and reduced proline under water stress. • PCA revealed photosynthesis and nutrients as key yield drivers under drought. • F+BH under deficit irrigation achieved the highest benefit-to-cost ratio (1.73).