Effect of Salicylic Acid and Potassium Application on Yield and Grain Nutritional Quality of Wheat under Drought Stress Condition

Drought stress severely reduces wheat productivity and affects grain quality. In this study the effects of combined application of salicylic acid (SA) and potassium (K) on yield and grain quality of wheat under drought stress condition was investigated. Winter wheat cultivar Minaminokaori was grown in pots in a greenhouse, and subjected to 3 levels of K (50, 100 and 200 kg ha−1) fertilizer applications. The plants were foliar sprayed with SA (0.7 mM) at heading stage, and then imposed to the drought stress until grain maturity. Drought stress decreased grain yield by 41.1%, starch content by 10.2% and water-soluble pentosan content by 3.5% in comparison to well-irrigated control. However, grain crude protein content, total pentosan content and phytate phosphorus content were increased by 33.0%, 17.9%, and 13.4% respectively. Under the same drought condition, the application of combined SA and high K levels has increased grain yield (13.3%), starch (12.2%) and water-soluble pentosan content (20.3%) compared to SA-untreated with low level of K fertilizer. In addition, SA application decreased the percentage of phytate phosphorus to total phosphorus under drought stress. These results suggested that combined treatment of SA foliar application and a higher doses of K fertilizer can partially improve wheat productivity, grain nutritional quality, particularly water-soluble pentosan that influences the bread-making quality, without increasing the anti-nutrient component phytate under drought stress condition.