Responses of millet growth, soil nutrition and microbial community composition to selenium fertilization

Selenium (Se), as a trace element, is of great importance for both crop growth and human healthy. Deficiency of Se can lead to a variety of diseases, which has drawn significant attention. Recently, various strategies have been employed for Se biofortification in modern agriculture. Se biofortified Millet (Setaria italica (L.)), which is one of the main grains in China, is beneficial for overcoming Se deficiency in the diets. In this study, two Se-enriched millet variety (Jigu 38 and Jigu 19) was cultivated and four Se fertilization levels (Se0, Se1, Se2, Se3 were applied at the level of 0, 15, 30, and 45 g ha-1Na2SeO3, respectively) were conducted, and the millet growth characteristics, soil nutrition contents and microbial community composition were analyzed. The results showed that Se2 treatment significantly improved the crop growth and yield of both millet varieties, and also increased the Se content in the grain as compared to **. In soil, the activities of acid phosphatase and sucrase but not soil pH, actual Se content, and urease activity were significantly increased in Se fertilized soil rhizosphere. Some beneficial bacteria and fungi were found to have been increased in relative abundance in different stages after Se fertilization application, but there was a possibility that harmful fungi or microorganisms with unknown ecological functions may have been enriched at the same time. This study had important implications for the development of Se-enriched millet and understanding of Se biofortification of millet from plant growth, rhizosphere soil nutrients, and microbial community composition.