柠檬酸和EDTA-Na_2对黑麦草吸收Pb及营养元素特性的影响

Effects of Citric Acid or EDTA-Na_2 on the Absorption Characteristic of Pb and Nutrient Elements of Lolium perenne L.

为探究柠檬酸或EDTA-Na_2对Pb污染下黑麦草(Lolium perenne L.)吸收Pb和营养元素特性的影响,对水培黑麦草进行不同处理,研究黑麦草一些生理生化指标的变化。结果表明,与对照相比,Pb处理降低黑麦草干重,增加质膜透性和根系脱氢酶活性,且在叶和根中积累Pb,而叶和根中6种营养元素含量的变化不尽相同。与Pb处理同时加入低浓度的柠檬酸或EDTA-Na_2对其生长影响较小,且叶片的Pb积累量较低;而同时加入高浓度的柠檬酸或EDTA-Na_2,虽然强化Pb在叶片中的积累,但是加重了生长的抑制作用和营养元素的稳态失衡;1 mmol L^(–1)的柠檬酸强化叶片积累Pb的效应强于同浓度的EDTA-Na_2,而5和10 mmol L^(–1)柠檬酸的强化作用则弱于同浓度的EDTA-Na_2。因此,适当浓度的柠檬酸或EDTA-Na_2在治理Pb污染环境中具有一定作用。

In order to understand the effects of citric acid or EDTA-Na2 on the absorption characteristic of Pb and six nutrient elements of Lolium perenne L., the contents of Pb, N, P, K, Ca, Mg and Fe, as well as the dry weight, the root dehydrogenase activity and the membrane permeability in L. perenne with different treatments were studied. The results showed that the dry weight of L. perenne decreased, and root dehydrogenase activity and membrane permeability increased under Pb pollution, the changes in six nutrient elements contents in leaf and root varied, and Pb accumulated in both of leaf and root. Treated with low concentration of citric acid or EDTA-Na2, there was a little influence on growth of L. perenne, and the Pb accumulation in leaf was low. However, treated with high concentration of citric acid or EDTA-Na2, the growth of L. perenne not only showed serious inhibition, but also coursed imbalance of nutrients homeostasis, and the accumulation of Pb in leaf increased. Then, L. perenne could accumulate more Pb in leaf treated with 1 mmol L^-1 citric acid or 5 and 10 mmol L^-1 EDTA-Na2. Therefore, it was suggested that suitable concentration of citric acid or EDTA-Na2 could play certain role in control environment of Pb pollution.