Application of Potassium Improves Yield and Quality Under Drought Stress by Regulating Nutrient Use Efficiency in Wheat

Drought stress is a major abiotic constraint that severely limits growth, yield formation, and grain quality in wheat. Potassium (K) application is known to alleviate drought stress in crops. However, the integrated effects of K fertilization on yield, grain nutritional and quality, and nutrient use efficiency under post-flowering drought stress remains poorly understood. In this study, two-year pot experiments were conducted with two wheat cultivars under well-watered (75% field capacity) or post-flowering drought (~40% field capacity) conditions, combined with K fertilization (120 kg K2O ha−1) or no K (0 kg K2O ha−1), using a randomized complete block design. The results showed that K application significantly improved wheat performance under post-flowering drought stress. Specifically, it increased plant biomass, thousand-grain weight, grain yield, K accumulation, and K uptake efficiency, while also elevating grain contents of calcium, magnesium, zinc, total starch, and wet gluten. In conclusion, K fertilization not only mitigates the adverse effects of post-flowering drought stress in wheat, but also improves yield, grain quality, and nutrient use efficiency. These findings offer valuable insights for high-efficiency nutrient management and wheat production under drought regions.