The effect of selenium (Se) on the biomass, root/shoot ratio and stem diameter of lettuce at different growth stage under different salt concentrations was studied in pot experiment with substrates .The results showed that the biomass, root/shoot ratio and stem diameter of lettuce were significantly reduced under salt stress. The salt stress on lettuce was reliefed to some extent through adding Se to different salt concentrations, adding Se increased biomass and stem diameter of lettuce. The root/shoot ratio increased in the treatment of Se adding to all the salt stress in the early and middle growth period of lettuce, it decreased in the treatment of selenium adding to high salt stress except the treatment of adding 1.5 mg/kg selenium in the late growth period.
