The effects of foliar application of selenium nanoparticles (SeNPs) on rice growth and Se accumulation has been studied, but soil application of SeNPs on rice Se uptake and its transformation in soil remain limited. Water management is a key agronomic practice in rice cultivation. This study examined the effects of varying water management regimes (continuous flooding [CF] and alternating wet and dry [AWD]) and concentrations (0, 0.5, and 2 mg·kg