2.1 Plant growth.
The wheat plants used in the experiments were grown in the intelligent greenhouse of the College of Agriculture, China Agricultural University (Beijing, China). Wheat seeds (Liaochun10) were soaked in 0.5% sodium hypochlorite for 30 min and then cleaned five times with distilled water. The wheat seeds were planted in plastic pots (14 cm in diameter and 11 cm in height) containing organic soil (nutritional soil: peat: vermiculite = 4:1:1). During the whole experiment period, the plants maintained the relative humidity at 70% at the day/night temperature of 25/20 ℃ with a day/night cycle of 14/10 h and the light intensity at 80µmol m-2 s-1. The nano-Se (50-78 nm) applied in this study was characterized and reported in our previous study (Dong Li, An, Wu, Li, & Pan, 2020). The plant experiment was separated into four groups including three levels of nano-Se treatment (5, 10, and 20mg/L) and the controls. These four treatments each had five duplicates.