土壤灭菌和杀真菌剂对紫花苜蓿生长和重金属累积的影响

Effects of Soil Sterilization and Fungicide Application on Growth and Heavy Metal Accumulation of Alfalfa(Medicago sativa L.)

以云南会泽铅锌矿周边重金属污染的农田土壤为基质,开展室内盆栽试验,研究土壤灭菌和杀真菌剂(苯菌灵)对紫花苜蓿的生长、光合色素含量、部分抗氧化生理、重金属含量与累积量的影响。结果表明:土壤灭菌显著影响苜蓿的抗氧化生理,导致巯基含量减少54%,丙二醛含量增加44%;显著降低光合色素含量和植株的生长,叶绿素a、叶绿素b和类胡萝卜素含量分别下降27%、23%和30%,株高降低45%,地上部和地下部生物量分别减少74%和85%;土壤灭菌和施用苯菌灵均显著增加土壤有效Pb含量和苜蓿地下部Pb的含量,减少苜蓿地下部Zn的含量;土壤灭菌还显著增加苜蓿地上部Cd的含量;土壤灭菌极显著减少苜蓿对重金属的累积,植株Pb、Zn、Cd和Cu的累积量分别下降74%、78%、68%和76%;施用苯菌灵对苜蓿生长、抗氧化生理及重金属累积的影响均不显著。总之,完全消除土壤微生物明显降低了苜蓿对重金属的耐性与累积能力,土壤微生物对植物耐受重金属有重要作用。

Research has shown that soil microbes have profound impacts on plant tolerance to heavy metals. A greenhouse experiment was carried out to investigate the effects of soil sterilization and fungicide(benomyl) application on growth, antioxidant physiology and heavy metal accumulation of alfalfa(Medicago sativa L.) grown in heavy metals-polluted soils from a lead-zinc mining area of Huize, Yunnan Province. Soil sterilization significantly increased malondialdehyde(MDA)content by 44%, but decreased-SH content by 54%, chlorophyll a by 27%, chlorophyll b by 23%, and carotenoid content by 30%. Plant height, shoot biomass and root biomass were also reduced by soil sterilization by 45%, 74% and 85%, respectively. Both soil sterilization and benomyl application led to a significant increase in available Pb in soils and Pb content in alfalfa roots but a decrease in Zn content in the roots. In addition, soil sterilization significantly increased Cd content of alfalfa shoots. The accumulation of Pb, Zn, Cd and Cu in alfalfa was significantly decreased by soil sterilization by 74%, 78%, 68%and 76%, respectively. Applying benomyl did not significantly affect growth, antioxidant physiology, and heavy metal accumulation of alfalfa. These results indicate that soil microbial elimination reduces plant′s ability to tolerate and accumulate heavy metals.