关键词: 茭白, 镉, 残留含量

Abstract: Changes of some physiological and biochemical indexes in leaves and roots of the Zizania latifolia were studied with single-harvested cultivar Jiangshujiao and double-harvested cultivar Fenghongzao which cultured in reed sediment substrate with different Cd2 + concentrations. The Cd²⁺ residues in Zizania galls were also determined. The results showed that, after about 2 months of treatment, the soluble protein content and net photosynthetic rate of functional leaves arrived the maximum when the Cd²⁺ concentration was 25 mg·L^-1,and then decreased with increasing Cd²⁺ concentration. The activities of POD, PPO increased with the increasing Cd²⁺ concentration until 200 mg·L^-1. The Cd²⁺ residues in Zizania galls in all treatments were lower than the national maximum residue standards of non2polluted vegetables. The Cd2 + residues in Fenghongzao gallswere higher than those in Jiangshujiao in all treatments. The Cd²⁺ accumulation in next summer-harvested gallswas higher observably than those in first-autumn-harvested galls of Fenghongzao. It is considered that the Zizania latifolia has a high tolerance to Cd²⁺ stress while has a low Cd²⁺ bio-enrichment in the edible organ. A significant positive correlation was observed between the Cd²⁺ residual quantity in the galls
and the time of Cd²⁺ treatment.

Key words: Z izan ia la tifolia, Cadmium, Residue