不同种类蔬菜幼苗对铅的敏感性研究

采用水培方法,探讨了小白菜（叶菜类）、黄瓜、豇豆（瓜果类）和萝卜（根茎类）幼苗对重金属Pb的吸收累积量大小及Pb对其幼苗生长发育的影响。结果表明,蔬菜幼苗根和茎叶累积Pb量均随Pb处理浓度的增加而显著增加（P〈0.05）,且同一处理浓度下根中Pb含量远高于茎叶中Pb含量。蔬菜苗期根对Pb的敏感性排序为黄瓜〉小白菜〉萝卜〉豇豆,茎叶为小白菜〉萝卜〉黄瓜〉豇豆。低浓度的Pb对叶绿素的合成有一定程度的刺激作用,随Pb浓度增加,叶片中叶绿素含量降低。小白菜过氧化氢酶（CAT）含量随着Pb浓度的增大先增大后缓慢降低,其他3种蔬菜则表现为先减小后增大的趋势。此外,黄瓜和豇豆出芽率显著降低,4种蔬菜幼苗根长均明显受到抑制。

Sensitivity of Different Vegetable Seedlings to Lead

Lead is not a necessary element to crop growth but a pollutant with accumulation problems.In this study,we defined that the higher cumulative amount of Pb in the vegetable seedlings,the more sensitivity of vegetables to Pb.According to the sensitivities of different types of vegetables to Pb,we could infer the influences of Pb on the vegetable growth.The effects of Pb of different concentrations on seed germination rates,seedling growth,physiological responses and Pb contents in shoots and roots of four kinds of vegetables（leafy vegetables：Chinese cab-bage;fruit vegetables：cucumber,cowpea;root vegetables：radish）were studied by means of water culture experiment.The results showed that Pb contents in all roots and shoots of the four vegetable seedlings had highly positive correlation with the concentration of Pb（P0.05）,and Pb was easily absorbed and accumulated in roots than in shoots.The ascending sort of Pb enrichment capacity in the roots of these tested vegetable seedlings was cucumber Chinese cabbage radish cowpea,and in the shoots,it was Chinese cabbage radish cucumber cow-pea.These indicated that cucumber was most sensitive to Pb among the roots of tested vegetables,while Chinese cabbage was most sensitive to Pb among the shoots.With the increase of the Pb concentration,chlorophyll contents in the four tested vegetables increased first and de-creased afterwards.Catalase（CAT）contents in Chinese cabbage had the same performance as the chlorophyll,but which in the other tested vegetables had a reversed trend.By the way,we could get another conclusion that vegetable germination rates of cucumber and cowper,seedling root lengths of all decreased significantly under the same experiment conditions.