铬对3种烟草的毒害效应及毒害临界值的研究

通过土壤盆栽实验．研究3个烟草品种在添加了0、30、60、90mg／kgCr^6＋的土壤中的生长性状及生理差异。结果表明：在Cr添加浓度范围内，随时间变化，三种烟草相对于对照烟草株高变化呈现先递减后递增的趋势。烟草移栽后54～74d期间．对Cr毒害较敏感。低浓度Cr对烟草叶片超氧化物歧化酶（SOD）活性有促进作用，高浓度则表现抑制；过氧化物酶（POD）、丙二醛（MDA）活性随Cr添加量的增加呈明显的上升趋势。烟草下部叶生物量对Cr毒害最敏感。3种烟草不同部位的Cr毒害效应浓度（EC20）呈上部叶〉中部叶〉茎〉下部叶的趋势。3种烟草中部叶的EC20分别为10．59（翠碧1号）、9．54（K326）和7．84mg／kg（云烟87）。云烟87中部叶的EC20值可以作为福建烟区土壤Cr毒害临界值制定的依据。

Toxicity Effects of Chromium on Three Tobacco Varieties and Cr Toxicity Threshold for Tobacco-Production Soils

The growth and physiological characteristics of 3 tobacco varieties, Cuibi-1, K326 and Yunyan-87, were studied by pot experiments of which the soils were amended with 0 mg/kg, 30 mg/kg, 60 mg/kg, 90 mg/kg Cr^6＋, respectively. The results showed that the sensibility to Cr toxicity of the heights of 3 tobacco varieties increased first and then declined with time. As a whole, the tobaccos were more sensitive to Cr toxicity during 40-50 days after transplanting than other period. Low Cr addition promoted whereas higher Cr incorporation inhibited SOD activity. The activities of POD and MDA increased with increasing amount of Cr added. The EC20 values of different parts of the tobacco were in the order of upper leaf 〉 middle leaf 〉 stem 〉 lower leaf. The EC20 values of the middle leaves of the three tobacco varieties were 10.59 mg/kg（Cuibi-1）, 9.54 mg/kg（K326）and 7.84 mg/kg（Yunyan-87）, respectively. The EC：o of the middle leaf of Yunyan-87 can be used as the basis for establishing Cr toxicity threshold of tobacco-production soils in Fujian Province.