玉米生长指标对土壤外源铜镍毒害的敏感性比较研究

在重金属污染土壤的生态风险评价中，评价指标的确定至关重要，为此在田间试验条件下研究了不同添加水平的Cu和Ni（0、50、100、200、400、800、1600、3200mg·kg^-1）对玉米的毒害效应，并比较了玉米生长指标对Cu和Ni毒害的敏感性。结果表明，在相同的添加水平下Ni对玉米的毒害高于Cu；对Cu和Ni而言，苗期各项指标的敏感性依次为叶面积〉株高〉出苗率或可见叶数。与其他指标相比，叶面积是判别Cu和Ni污染最敏感的指标。苗期的株高、成熟期籽粒和秸秆的干重，这3项指标的敏感性接近，是较为敏感的指标，而出苗率和可见叶数与其他指标相比敏感性较差。因此，苗期株高和叶面积可以作为Cu或Ni毒害的评价指标。同时，两茬玉米的研究结果表明，土壤中的Cu对两茬玉米毒害的差异不显著，而土壤中的Ni对两茬玉米毒害的差异显著，说明Ni在石灰性土壤中的老化效应明显。

Comparison of Sensitive Endpoints of Maize Growth to the Toxicity of Copper and Nickel Added to Soil

The realistic endpoints are very important in ecological risk assessment of soils contaminated with heavy metals, tn the present study, a field trial was carried out to study the toxicity of Cu and Ni added to soils to maize plant growth and to compare the sensitivity of different assessment endpoints for maize growth to Cu or Ni toxicity with a wide range of Cu or Ni added to soil（0, 50, 100, 200, 400, 800, 1 600, 3 200 mg.kg^-1）. The results showed that Ni is more toxic to maize growth than Cu at the same application rates. Based on the assessment of the toxicity of copper and nickel to maize plant growth, the sensitivity of endpoints of seedling growth was in the order leaf area〉plant height〉 seedling emergence rate or leaf number. Leaf area was the most sensitive endpoint of the four evaluated. The endpoints of plant height, grain yield and straw biomass were sensitive to Cu or Ni toxicity. Seedling emergence rate and leaf number are the least sensitive endpoints. Therefore, leaf area and plant height can be used as bioindicators of copper- and nickel-contaminated soils. Also, the results about the change in the toxicity of Cu and Ni with two successive crops indicated that there was no significant difference in Cu toxicity, while a significant decrease in Ni toxicity, which indicated a significant aging effect of Ni.