Effects of selenium (Se) uptake on plant growth and yield in common buckwheat (Fagopyrum esculentum Moench)

Selenium (Se) is an essential microelement for humans and a beneficial element for plants. Increasing grain yield and Se content simultaneously in crop is of great significance. In the present study, we hypothesize that the delay in the application of appropriate concentrations of Se contributes to increased grain yield and Se content. A two-year field experiment was conducted to investigate the effects of three concentrations of selenite (0, 5, or 20 g ha−1) sprayed at two stages (initial or peak flowering stage) on the yield, yield components, agronomic traits, photosynthetic characteristics, dry matter, and Se accumulation and distribution of common buckwheat plants. Results indicated that low concentration of Se promoted leaf photosynthesis more than higher concentration. The grain dry matter weight and Se content increased linearly with increasing Se application concentration. Delayed growth stages resulted in 2.65 and 1.66 times higher grain Se content in plants sprayed with low and high Se concentrations, respectively. Both Se application rate and spray time contributed significantly to grain yield. The grain produced under low-concentration spraying of Se at the IFS was safe for human consumption. In the present study, we suggest that foliar application of Se at 5 g ha−1 at the IFS is the most efficient way to improve grain Se accumulation and yield in common buckwheat. Future research may focus on quantifying the species of Se and localizing the Se element distribution in grains.