Bio-nano selenium fertilizer improves the yield, quality, and organic selenium content in rice

To investigate the impact of bio-nano Se on rice yield and quality and Se accumulation, three different forms of Se were applied: Se nanoparticles (SeNPs) synthesized by Proteus penneri LAB-1, a conventional inorganic Se fertilizer (sodium selenite) and an organic Se fertilizer (selenomethionine). The relative chlorophyll content of rice increased in plants treated with the different Se treatments and reached the highest level in the 5 mg/L bio-nano Se treatment. However, the height of rice showed little change. Applying 20 mg/L SeNPs increased rice yield by about 5% compared with organic Se treatment and 6% with inorganic Se treatment. Compared with the control, spraying 20 mg/L bio-nano, organic and inorganic Se on the leaf surface increased the soluble sugar content of rice by about 70%, 59% and 61%, respectively, and the amylose content by 15%, 11% and 10% and decreased soluble protein content by 25%, 18% and 22%, respectively. The Se content of rice increased with the increasing of spraying Se concentration. After spraying 10 mg/L of bio-nano Se, the Se content in the rice reached 271.2–306.5 µg/kg, and the proportion of organic Se was over 85.0%, which met the Se-rich rice and safety standards. This study provides a reference for determining the appropriate bio-nano Se supply level and developing Se-rich rice.