Grain yield, starch, protein, and nutritional element concentrations of winter wheat exposed to enhanced UV-B during different growth stages

• UV-B effects on wheat yield and quality depended on radiation stages.
• UV-B radiation during heading and flowering stages significantly decreased yield.
• UV-B radiation during heading and flowering stages changed wheat quality.
• UV-B effects during heading and flowering stages were more than that during the other stages.

In order to alleviate the damage of UV-B on plants, it is important to determine at which growth stages are plants more sensitive to enhanced UV-B. The objective of the study was to evaluate the effects of UV-B on wheat yield and quality during different growth stages. Enhanced UV-B during heading, flowering and the whole growth stages (UCK, from seedling to grain filling) decreased yield by 6.6, 4.4 and 9.6%, respectively. Protein content in grain was decreased by enhanced UV-B during flowering and UCK over the control. Amylose, amylopectin and total starch content were not affected by UV-B treatments. UCK treatment resulted in a decrease of nitrogen (N), phosphorus (P) and iron (Fe) concentrations, while zinc (Zn) and manganese (Mn) concentrations increased. Enhanced UV-B during tillering, heading and flowering stages reduced Fe concentration, but increased Mn, copper (Cu) and Zn (except for flowering) concentrations. The results indicated that the changes in wheat yield and quality induced by enhanced UV-B during the whole growth stage were probably from the effects of UV-B radiation during heading and flowering stages. Therefore, to better defend the damage of UV-B to wheat, some methods should be undertaken during heading and flowering stages.