Effects of leaf leachates of Zanthoxylum bungeanum on soil enzymes, chemical properties and its own seedlings growth

The leaf leachates (20, 40, 60, 80 g L⁻¹) of Zanthoxylum bungeanum affected the soil enzymatic properties and growth of its own seedlings. Leaf leachates at concentrations of 60, 80 g L⁻¹, significantly inhibited the seedlings root biomass. With the increase in leaf leachate concentrations, soil polyphenoloxidase activities increased greatly but soil catalase, protease and acid phosphatase were decreased significantly. The lower concentration (20 g L⁻¹) of leaf leachates had no effect on ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) of seedlings but higher concentrations were inhibitory. Likewise, the malondialdehyde (MDA) contents in seedling leaves decreased significantly at 20 g L⁻¹ and increased at higher concentrations (over 60 g L⁻¹). Soil available nitrogen was greatly enhanced at the 20 g L⁻¹ concentration, but declined at higher concentrations. However, soil available phosphorus decreased in all concentrations. Some significant relationships were observed among the soil chemical properties, enzymatic activities and the seedling physiological indices with leaf leachates.