Abstract: With meadow brown soil as test soil, this paper studied the effects of single and combined pollution of Pb²⁺ and 1,4-dichlorobenzene (PDB) on the germination rate, biomass production, and shoot and root elongation of wheat (Triticum aestivum) and Chinese cabbage (Brassica pekimensis). The seeds of wheat and Chinese cabbage were exposed to various concentrations of PDB with or without lead addition. The sensitivity of test crops to the toxicity of the pollutants was in the sequence of root elongation>shoot elongation > biomass fresh weight > biomass dry weight and germination rate. When the concentration of added Pb²⁺ was 500 mg·kg^-1, lead and PDB had a synergistic effect of inhibiting shoot and root elongation. When the concentration of added Pb²⁺ was 2 000 mg·kg^-1, the pollutants had a synergistic effect of inhibiting shoot elongation but an antagonistic effect of inhibiting root elongation. For both wheat and Chinese cabbage, the joint toxicity of lead and PDB was more dependent on PDB’s concentration.

Key words: Amount of soil water stored, Forest land, Wasteland, Loess Plateau, Annual changes of soil moisture