锰和镉对农作物生长的毒性效应

Ecotoxicological Effects of Mn,Cd and Mn-Cd Combined Contamination on Crops

目的研究锰(Mn)和镉(Cd)单一及联合染毒对农作物生长的影响。方法以大白菜、莴笋、豇豆和紫花苜蓿种子为受试植物,通过种子发芽和根伸长试验测定不同浓度的Mn2+(5～300 mg/L)、Cd2+(0.25～18 mg/L)单一及复合染毒的生态毒性效应。结果Mn、Cd单一及联合染毒对4种农作物种子发芽抑制率远小于对根伸长的抑制率,根伸长抑制率与Mn2+、Cd2+染毒浓度呈统计学正相关。4种农作物中,莴笋对Mn、Cd染毒最为敏感,豇豆和紫花苜蓿对Mn染毒的耐受性较大。结论根伸长抑制率比种子发芽抑制率更能准确反映重金属的毒理效应。在Mn、Cd污染共存时,Mn和Cd主要表现为拮抗作用。

Objective To study the ecotoxicological effect of Mn, Cd and Mn-Cd combined contamination on crops. Methods Chinese cabbage （Brassica pekimensis）, lettuce （Lactuca sativa var. angustana Irish）, cowpea （Vigna unguiculata） and alfalfa （Medicago sativa L.） seeds were used in seed germination and root elongation tests. Results Research findings indicated that inhibition rates of heavy metals （individual or combined） on the seed germination were much lower than those on the root elongation. Inhibition rate of root elongation proved positively correlated to the concentration of Mn and Cd （P〈0.01）. Of the four test crops, lettuce was most sensitive to the Mn and Cd treatment, while legume cowpea and alfalfa were more resistant to Mn contamination. Conclusion Inhibition rate of root elongation is a better indication of toxicological effect of heavy metals. When Mn-Cd combined contamination occurs, an antagonistic effect between Mn and Cd is mostly displayed.