茭白对苇末基质中镉的生理反应及其镉的残留

Influence of Cadmium on Metabolism and Its Residual Quantity in Gall of Zizania latifolia Cultured in Reed Sediment Substrate

以茭白(Zizania latifoliaTurcz.)单季茭品种'蒋墅茭'和双季茭品种'葑红早'为试材,采用苇末基质栽培方式进行不同浓度Cd2+胁迫处理,测定其生长过程中部分生理指标及肉质茎中Cd2+残留含量的变化。结果表明:处理近两个月后,茭白叶片和根系中可溶性蛋白含量及净光合速率等在Cd2+浓度为25mg.L-1时高于对照,然后随浓度升高逐渐降低;POD和PPO活性随Cd2+浓度升高而增加,直至200mg.L-1才出现降低;各处理肉质茎中Cd2+的残留量均未超过无公害蔬菜国家标准的限量值,葑红早各处理同比均高于蒋墅茭,而且其第2年夏茭肉质茎中的Cd2+含量显著高于第1年的秋茭。表明茭白对Cd2+的忍耐性较强,虽然产品器官中的残留含量随处理时间延长而呈增加趋势,但生物富集程度较低。

Changes of some physiological and biochemical indexes in leaves and roots of the Zizania latifolia were studied with single-harvested cuhivar Jiangshujiao and double-harvested cuhivar Fenghongzao which cultured in reed sediment substrate with different Cd^2＋ concentrations. The Cd^2＋ 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 Cd^2＋ concentration was 25 mg · L^-1, and then decreased with increasing Cd^2＋ concentration. The activities of POD, PPO increased with the increasing Cd^2＋ concentration until 200 mg · L^-1. The Cd^2＋ residues in Zizania galls in all treatments were lower than the national maximum residue standards of non-polluted vegetables. The Cd^2＋ residues in Fenghongzao galls were higher than those in Jiangshujiao in all treatments. The Cd^2＋ accumulation in next summer-harvested galls was higher observably than those in first-autumn-harvested galls of Fenghongzao. It is consid- ered 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 Cd^2＋ residual quantity in the galls and the time of Cd^2＋ treatment.