The effects of foliar spraying of sodium selenite at different concentrations on the yield and selenium content of coix seed grains

To explore the effects of foliar spraying of different concentrations of sodium selenite on the yield and selenium content of coix seed grains, and to provide theoretical basis and solutions for the selenium-enriched technology of coix seed grains. Two local coix seed varieties, GUI Nong Yi No. 7 and Xing Ren Xiao Bai Ke, were selected for the experiment. Sodium selenite H1 to H4 and one clear water control（H0）were sprayed on the leaves of coix seeds during the panicle stage and the grain filling stage respectively. Each variety and treatment were repeated three times, totaling 90 experimental plots. Through uniform planting methods and field management, yield was measured after the grains matured and samples were collected to detect relevant indicators. The results showed that the selenium content in the grains and the enrichment coefficient increased overall with the increase in spraying concentration. At medium-high concentrations H3 and H4, the selenium content in the grains reached the ideal selenium-enrichment effect and was significantly higher than the low-concentration treatments and the control. However, the soil selenium content and available selenium content varied due to the varieties and plots, and did not show a consistent linear pattern. Regarding the impact on the yield of the two varieties, Guinan Yi7 had a certain yield increase effect at H1 and H3, while Xingren Xiaobaihe had the same yield level at H0 and H3, and showed significant yield reduction at H1, H2, and H4. Research suggests that foliar spraying of sodium selenite during the booting and filling stages of coix seed is an effective measure to increase the selenium content in coix seed grains. Taking into account the effect of increasing the selenium content in grains, cost input and potential risks comprehensively, and in combination with the actual production, foliar spraying of sodium selenite with a selenium concentration of 12 mg·L⁻¹ and a dosage of 666 L·hm⁻² is the recommended scheme for the production of selenium-enriched coix seed products.