Abstract: The objective of this study is to explore the effect of applying zinc (Zn) and silicon (Si) as foliar sprays on the accumulation of cadmium (Cd) in lettuce plants growing in lightly Cd-polluted soil. The Cd contents in various organs of lettuce and its subcellular distribution patterns were determined, and the morphological responses of lettuce plants were analyzed. The results of the study show that foliar spraying with Zn and Si reduced the Cd contents in edible parts of lettuce plants by 10.51%-45.09%. The Cd content in the edible parts of lettuce treated with Si was lower than the limit specified in the national food safety standard. The concentration of Zn/Si was the main factor affecting the accumulation of Cd in lettuce, with higher concentrations having a stronger effect to reduce Cd accumulation. Foliar spraying with Si or Zn promoted the conversion of Cd from an active to an inactive state, significantly increased the proportion of sodium chloride-extracted Cd in various organs of lettuce, and reduced the proportion of active Cd in the roots, stems, and leaves by 75.83%, 60.38%, and 80.03%, respectively. Foliar spraying with Si or Zn significantly reduced the distribution of Cd in root organelles, and reduced the distribution of Cd in stem and leaf organelles by more than 30%. Foliar spraying with Zn and Si could reduce the activity of the heavy metal Cd in lettuce roots and prevent and control Cd accumulation in the edible parts of lettuce plants.

Key words: Cd, lettuce, Zn, Si, foliar spraying