铅对光头稗幼苗生长的影响及其抗性生理研究

Effects of Lead Pollution on the Growth of Echinochloa colonum Seedlings and the Physiological Characteristics of Their Endurance

该试验通过水培方法,研究了不同浓度铅污染对农田杂草光头稗幼苗生长的影响,同时分析测定了其抗性生理指标的改变以及叶片和根的Pb富集含量。结果表明,低浓度的Pb污染(<50 mg.L-1)对光头稗幼苗的生长无明显抑制现象,甚至促进幼苗的生长,生物量及叶绿素含量均略微升高。但随Pb浓度增加(50～400 mg.L-1)则显示出一定的负效应,光头稗与对照组相比,植株矮小,根短且数目少,植株干重、鲜重均显著减少,叶片发黄,叶片色素含量下降。同时,随Pb浓度增加,叶片和根中的Pb含量增加,叶片和根细胞膜透性增大,电导率显著升高,O2-.产生速率和MDA含量上升,抗氧化保护酶POD活性也呈增大趋势,而SOD活性先增后减,可见这两种保护性酶均可被激活以抵抗铅胁迫,但POD起主要作用。

The effect of Lead（Pb） pollution on the seedling growth, eco-physiological index and Pb concentrations of Echinochloa colonum was studied by means of water cultivation experiments. The results showed that under low concentration of Pb（〈50 mg.L^-1）, the growth of Echinochloa colonum seedling were not suppressed, moreover promoting the growth of the seedling, the biomass and the content of chlorophyll rised slightly. In general, with an increase in Pb concentration, an obvious negative effect on the growth of Echinochloa colonum seedlings was observed. The seedlings under high concentration of Pb（50-400 mg·L^-1） were shorter and small- er, their fibrous roots were shorter and fewer, and their fresh,dry weight and the content of chlorophylls decreased drastically. Meanwhile, with an increased in Pb concentration, the membrance penetration, electric conductivity, velocity of O2·^-production and MDA content of leaf and root cells increased. The activeties of POD increased, but the activeties of SOD appeared to increase at the beginning stage and then decreased. POD played an important role in the two antioxidant enzymes.