Effects of foliar-sprayed of selenium on distribution and accumulation of selenium in subcellular components of rice leaves

Abstract: Foliar selenium spraying is an effective agronomic fortification to increase the selenium content of crops. Exploring the distribution, accumulation characteristics and influencing factors of selenium in rice leaf fractions can provide support for improving the utilization efficiency of foliar selenium application and reducing the ecological and environmental risks of selenium. This study compared the effects of different selenium forms, concentrations, treatment times and different surfactant carriers on the distribution and accumulation of selenium in the subcellular fractions of rice leaves using the leaf in vitro culture technique. The results showed that: (1) Selenium was mainly distributed in the cell wall of rice leaves, followed by chloroplast and mitochondrial fractions, with the least in the cytosol. (2) The uptake capacity of sodium selenite in leaves within a few hours of leaf application of selenium fertiliser was significantly higher than that of nano-selenium, selenomethionine and yeast selenium, by 1.25-fold, 1.32-fold and 5.43-fold, respectively, and the migration capacity was about 1.26-fold higher than that of the remaining three. (3) The rice per The optimal amount of selenium applied to each leaf was 0.008 mg, at which time the selenium content in chloroplasts and mitochondria reached the maximum value. (4) 3-7 h after leaf application of selenium was the critical time point for selenium uptake and translocation in leaves. (5) Meanwhile, compared with cyclodextrins and alkylglycosides, the addition of rhamnolipids to exogenous selenium at a concentration of 30 mg·L-1 promoted selenium uptake in rice leaves better, and the content of the absorbed content increased by 0.8-fold. The above results lay the foundation for the subsequent understanding of selenium transport mechanisms in leaves, and also provide support for the optimization of selenium formulations, the establishment of scientific selenium application systems, and the reduction of selenium ecological and environmental risks in the future.