不同种类蔬菜苗期对镉的敏感性研究

Sensitivity of Different Vegetable Seedlings to Cadmium

产地环境中镉(Cd)对蔬菜的影响主要表现为蔬菜可食部分超标,高浓度时影响其生长发育,基于评述蔬菜幼苗对Cd的敏感性是按其对Cd的吸收累积量来排序,累积Cd量越高定义为该蔬菜幼苗对Cd越敏感,采用水培方法,探讨了Cd对小白菜(叶菜)、黄瓜、豇豆(果菜)和萝卜(根菜)幼苗吸收累积量及生长发育的影响。结果表明,蔬菜幼苗根和茎叶中累积Cd量均随Cd处理浓度的增加而显著增加(P<0.05)。同一处理浓度下根中Cd含量远高于茎叶中Cd含量,根和茎叶对Cd的累积强弱顺序也即蔬菜苗期对Cd的敏感性排序为小白菜>萝卜>黄瓜>豇豆;随Cd浓度增加,叶片中叶绿素含量降低,过氧化氢酶(CAT)含量升高;蔬菜出苗率、幼苗根长、植株鲜重显著降低。

Excessive accumulation of cadmium （Cd） in agricultural soil can influence growth and development of vegetables. On the basis of the amount of Cd uptake and accumulation, this paper evaluated the sensitivity of vegetable seedlings to Cd. The higher cumulative amount of Cd in the vegetable seedlings, the more sensitivity of vegetables to Cd. A hydroponic experiment was carried out to investigate the influences of Cd on different vegetables seedlings （leafy vegetables：Chinese cabbage; fruit vegetables：cucumber, eowpea; root vegetables：radish）. The results showed that, in all roots and shoots of vegetable seedlings, Cd contents was significantly increasing （P〈0.05） with increasing concentration of Cd, and at the same concentration, Cd was easily absorbed and accumulated in roots than in shoots. For the roots and shoots of these tested vegetables, Cd enrichment capacity in increasing order was Chinese cabbage〉radish〉cucumber〉cowpea. This indicated that Chinese cabbage was most sensitive to Cd among studied vegetables. Correspondingly, cowpea had been affected the most. Its seedling root length decreased significantly compared to comparison at Cd concentration of 0.1 mg·L^-1; when Cd concentration was 1.0 mg·L^-1, plant fresh weights were significantly lower; when Cd concentration was 5.0 mg·L^-1, there was a significant reduction of vegetable emergent seedling rates and roots could not normally grow. For four tested vegetables, as Cd concentration increased, eatalase contents （CAT） increased and chlorophyll contents decreased; vegetable emergent seedling rates, seedling root lengths and plant fresh weights decreased significantly.