Selenium uptake, dynamic changes in selenium content and its influence on photosynthesis and chlorophyll fluorescence in rice (Oryza sativa L.)

• The grain yield was increased due to appropriate application of Se.
• The grain Se content and photosynthetic system activity were closely associated with the application of Se.
• The effect of Se on the chlorophyll fluorescence and photosynthetic parameters of rice depend linearly on Se status in rice tissues.
• The photosynthetic or chlorophyll fluorescence parameters could be used to determine the sufficiency of Se treatment during the production of Se-rich rice.

Approximately two-thirds of the cultivated soil in China is Selenium (Se)-deficient, which often results in a lack of Se in the human population of this region. Therefore, developing an effective method to increase the Se content in crops has become a considerable effort. In this study, the uptake and distribution of Se, the dynamic changes in Se content, and the effects of different concentrations of Se on grain yield, photosynthetic parameters and chlorophyll fluorescence parameters (0–100 g Se ha−1) were measured in field experiments to clarify the response of rice crops to Se and the relationship between Se and the photosynthetic system. The results revealed that the grain yield was increased due to application of Se, peaking in areas treated with 50 g Se ha−1. The Se content in various parts of the rice plants significantly increased as the Se level increased. Furthermore, the Se content in each part of the rice plants decreased from the roots to the shoots to the grains, and the Se content in the shoots and the roots after Se treatment decreased from the tillering stage to the mature stage. However, little change in the grain Se content was detected throughout the entire grain growth phase. Furthermore, the application of Se enhanced photosynthesis by increasing the photosynthesis rate (Pn), the intercellular CO2 concentration (Ci) and the transpiration efficiency (E) of rice. Se treatment enhanced the activity of the photosynthetic system by increasing Fv, Fm, Fv/Fm and Fv/Fo and decreasing Fo. The present study suggests that the changes in both the photosynthetic system and the grain Se content were closely associated with the application of Se and that an increased Se concentration in rice could induce photosynthesis, thereby increasing the grain yield of rice. The photosynthetic or chlorophyll fluorescence parameters could be used to determine the sufficiency of Se treatment during the production of Se-rich rice.