Responses of physiological parameters, grain yield, and grain quality to foliar application of potassium nitrate in two contrasting winter wheat cultivars under salinity stress

An experiment was conducted to test whether foliar application of KNO3 on wheat in the heading stage could reduce salinity-induced injuries, produce high grain yield, and improve grain quality. Salt-resistant DK961 and salt-sensitive JN17 wheat cultivars under 0 or 100 mM-NaCl conditions were foliarly watered with distilled water or a 10 mM-KNO3 solution. The four treatments included: T-1 (CK1), 0 mM NaCl + distilled water; T-2, 0 mM NaCl + 10 mM KNO3; T-3 (CK2), 100 mM NaCl + distilled water; T-4, 100 mM NaCl + 10 mM KNO3. The results indicate that there were no differences (p > 0.05) in plant growth, grain yield, and grain quality between T-2 and T-1 in both cultivars, but these response variables were significantly lower in T-3 than in T-1. K+ : Na+ ratio, chlorophyll content, photosynthetic capacity, grain yield, flour yield, water absorbance, ash content, dough-development time and dough-stability time were significantly higher in T-4 than in T-3, while protein concentration, wet-gluten concentration, and antioxidant enzyme activities were lower. Although foliar application of KNO3 on JN17 enhanced plant growth, grain yield, and grain quality, these parameters were still lower in T-4 than in T-1. Our findings suggest that cultivating the salt-resistant wheat cultivar combined with foliar application of KNO3 at heading stage may alleviate salinity injuries and produce higher grain yield and better grain quality under saline conditions.