Physiological and Metabolomic Analyses of Exogenously Applied Sorbitol-Chelated Potassium Enhancing Drought Tolerance in Wheat

Potassium fertilization is a strategy to alleviate the impact of drought stress on wheat production. However, the effects of chelated potassium remain to be verified. In this study, 10% PEG-6000 was used to simulate moderate drought stress on hydroponically grown XinHua818 wheat ( Triticum aestivum L. ) seedlings, and the physiological and biochemical parameters of wheat sprayed with water (CK ₂ ), sorbitol (S), potassium chloride (K), potassium mixed with sorbitol (MK), and sorbitol-chelated potassium (SK) were monitored. Results showed that SK effectively alleviated the inhibitory effects of drought stress on seedling growth. The aboveground biomass of SK-treated seedlings was significantly higher than that of K and MK-treated seedlings, increasing by 15.66% and 20.00%, respectively. Compared to MK treatment, SK treatment significantly increased total chlorophyll content by 18.74% and reduced malondialdehyde levels by 16.02%. Superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity were also elevated in SK-treated seedlings compared to other treatments. Metabolomic analysis identified 51 differential metabolites in SK compared to CK ₂ treatment, including sugars, amino acids, lipids, plant hormones, carotenoids, flavonoids, and their derivatives. These metabolites were enriched in 18 metabolic pathways, notably α-linolenic acid metabolism, histidine metabolism, plant hormone signal transduction, carotenoid biosynthesis, and flavonoid biosynthesis, suggesting their potential role in enhancing drought tolerance in wheat and their broader significance in drought resistance research.