Enhancing wheat growth and yield under deficit irrigation using stress-tolerant plant-beneficial rhizobacteria

Drought is a major abiotic constraint limiting agricultural productivity globally, and is of particular concern in Pakistan. Harnessing drought-adapted plant growth-promoting rhizobacteria (PGPR) offers a promising strategy for sustaining wheat ( Triticum aestivum L.) production under water-limited conditions. In this study, 19 rhizobacterial strains were isolated from the rhizosphere of wheat grown in the hyper-arid Cholistan Desert of Pakistan and systematically screened for tolerance to multiple abiotic stresses, including PEG-induced drought (up to 20%), salinity (up to 15% NaCl), high temperature (up to 43 °C), and alkaline pH (up to 11). Strains were further characterized for plant growth-promoting traits (IAA production, phosphate and zinc solubilization, nitrogen fixation, and siderophore production) under both normal and stress conditions. Two highly promising multi-stress-tolerant strains, RF5 and RZ7, were selected and evaluated individually and in a consortium. Multi-location field trials were conducted across three distinct agroecological zones in Pakistan under deficit irrigation regimes (50% of recommended irrigation or skipped irrigations). Inoculation with the RF5 + RZ7 consortium, combined with 80% of the recommended NPK dose, resulted in significant improvements in wheat growth and productivity. Notably, grain yield increased by 18–24% compared to uninoculated controls under the same reduced fertilizer regime, while several key parameters (shoot biomass, chlorophyll content, and grain nutrient uptake) performed comparably to, or better than, the full fertilizer treatment. These positive effects were consistent across different wheat varieties and environmental conditions. These findings demonstrate that desert-adapted PGPR consortia can effectively mitigate drought stress, enhance nutrient use efficiency, and support sustainable wheat production under reduced-input conditions in arid and semi-arid regions.