Effects of exogenous zinc (ZnSO4·7H2O) on photosynthetic characteristics and grain quality of hybrid rice

Rice is an important food crop and zinc (Zn) is a beneficial microelement. However, there are few reports on the effect of zinc on yield and physiological characteristics of rice. In this study, exogenous zinc (ZnSO₄·7H₂O) was applied on plant to explore the effects of zinc on rice yield, quality and photosynthetic capacity. The results showed that appropriate concentration of zinc could increase the net photosynthetic rate (Pn) of rice leaves, and Zn2 (2 mg/L ZnSO₄•7H₂O) treatment was the most significant. However, the Zn treatment had no positive effect on rice yield except under the concentration of Zn2. Meanwhile, the result showed that Zn treatment could increase chalkiness degree (CD) and chalky grain rate (CGR), decreased amylose content (AC), increased protein content and changed protein composition of rice. The above indexes were most significant in Zn2 treatment. In addition, the Zn2 treatment significantly increased rapid viscosity analyzer (RVA) of rice. In conclusion, the results of this study suggested that Zn treatment could enhance the photosynthetic capacity of rice leaves, and improve the processing quality, taste quality and nutritional quality of rice. However, it will have a negative impact on the appearance quality of rice and cannot be used to increase rice production. This study will provide a basis for the application of zinc in rice production.