Enhancing Rice Taste Quality and Selenium Availability through Foliar Application of Selenium Nanoparticles

Rice consumers are increasingly attaching a demand for high-quality rice with exceptional taste and rich selenium availability. Selenium nanoparticles (Se NPs) have higher safety compared to ionic selenium and greater bioavailability compared to organic selenium. In this study, a 2-year field plot experiment was conducted to investigate the effects of foliar spraying at 50, 100, and 200 μmol L^-1 Se NPs during the gestation stage on the grain yield, selenium availability, and rice taste of conventional japonica Nanjing 9108, while exploring the physiological mechanisms underlying these effects, with spraying water as the control. Our results demonstrated that the spray of Se NPs significantly increased the selenium content in the leaves, which enhanced photosynthetic efficiency, improved grain filling, and ultimately boosted grain yield by 0.77-3.44% through an increase in 1000-grain weight. Additionally, Se NPs notably increased the selenium content in the edible parts of the grains. The application of Se NPs significantly elevated the activities of enzymes related to carbon and nitrogen metabolism like nitrate reductase (NR), glutamine synthetase (GS), ribulose-1,5-bisphosphate carboxylase (RuBPCase), and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo), thus harmonizing the relationship between these metabolic processes. While the protein content of rice showed no significant increase, the amylose content significantly decreased by 3.00-6.05%, resulting in a marked improvement in rice taste value and breakdown value by 1.63-8.03% and 9.23-33.72%, respectively, and a substantial decrease in setback value by 30.95-93.70%. Our findings indicated that selenium nanoparticles can be effectively applied as a foliar fertilizer at the gestation stage to enhance the yield, selenium nutrition, and taste of rice grains.