Foliar spraying of chitosan promotes selenium uptake in grapevine planted in soil supplemented with sodium selenite

Selenium (Se) is an important trace element for human body, and the fruit Se source is one option for human Se supplementation. To increase grapevine uptake of Se, grape seedlings were transplanted in soils supplemented with sodium selenite, and the concentrations of 0, 1, 2, 4, and 6 g L⁻¹ chitosan were sprayed on grapevine seedling leaves. Next, the effects of chitosan on grapevine Se uptake were studied. The chitosan-based foliar application increased the biomass, photosynthetic pigment content, antioxidant enzyme activity, and soluble protein content of grapevine. Chitosan application also increased the total Se, inorganic Se, and organic Se contents in grapevine. However, while the root organic Se was increased, the shoot inorganic Se was decreased. Compared to the control, the concentrations of 1, 2, 4, and 6 g L⁻¹ chitosan increased the shoot total Se content by 9.29%, 12.39%, 17.70%, and 14.16%, respectively. Chitosan application also increased the nitrogen (N), phosphorus (P), and potassium (K) contents in grapevine. Moreover, correlation, gray relational, principal component, and cluster analyses revealed that the root total Se, shoot total N, and root total K contents were the top three indicators closely associated with the shoot total Se content. Therefore, foliar-based chitosan application on grape seedlings can promote the Se uptake in grapevine under sodium selenite supply, and 4 g L⁻¹ is the best concentration.