Foliar application of chitosan enhances growth, root yield, and nutritional quality of sweet potato ( Ipomoea batatas (L.) Lam.)

Abstract

Sweet potato ( Ipomoea batatas (L.) Lam .) is a globally important crop prized for its nutritional value, yet sustainable methods to enhance its productivity and quality continue. The objective evaluated the effects of foliar‐applied biostimulant chitosan on physiological growth, leaf nutrient content, root nutritional content, and yield of sweet potato cv. Xushu 32. Spray solutions of chitosan at 0.0%, 0.1%, 0.3%, and 0.5% applied at 15, 60, and 90 days after transplanting were tested at Haizhou, Lianyungang, China. Pairwise comparisons among treatments identified the optimal chitosan spray concentration. The 2‐year field experiment used a randomized complete block design. Key results demonstrated that chitosan, particularly at 0.3% and 0.5%, increased vine length (up to 25.5%), stem girth (up to 24.1%), and leaf area per plant (up to 36.5%) versus the control. root yield per hectare was significantly increased, with the 0.3% treatment showing the highest improvement (∼22% over control). Furthermore, chitosan application elevated the root concentrations of mineral ash (up to 18.8%), total polyphenols (up to 60.1%), β‐carotene (up to 35.8%), and ascorbic acid (up to 54.9%). These results indicate that chitosan foliar spray effectively stimulates sweet potato growth and redirects metabolism to enrich root nutrient profiles. Chitosan represents a promising, sustainable agrochemical alternative for optimizing both yield and nutritional value in sweet potato cultivation, potentially reducing reliance on synthetic inputs.