西红柿铜毒害的土壤主控因子和预测模型研究

MAJOR SOIL FACTORS CONTROLLING COPPER TOXICITY TO TOMATO IN A WIDE RANGE OF CHINESE SOILS AND THE PREDICTABLE MODELS

通过有代表性的16种中国土壤的外源铜的西红柿毒害试验,发现淋洗(使用模拟的人工雨水滤洗定量的土壤样品)可以显著提高有机碳和盐分含量较高的土壤的毒性阈值。土壤pH是影响西红柿铜毒性阈值最重要的因子。基于土壤pH和有机碳含量的两因子回归方程能够很好地预测淋洗和非淋洗土壤上铜对西红柿生物量50%抑制的毒性阈值(EC50),且相关性均达到了80%以上。当考虑到黏粒含量或阳离子交换量对EC50的影响时,对于非淋洗和淋洗土壤来说,回归方程的决定系数R2分别提高到了0.862和0.891。本试验结果证明了利用土壤性状(土壤pH,有机碳含量以及黏粒含量或阳离子交换量)可以较好地预测土壤中外源铜对西红柿生长的毒性阈值。

Sixteen different soils, representative of the soils of China, were selected and sampled for an experiment on toxicity of extraneous copper to tomato growth. The samples were amended with CuCl2 to obtain a range of eight concentrations. Tomato shoot growth （21 d） test was performed in unleaehed and leached soils under controlled environment conditions. The results showed that the values of EC50 ,which were the concentrations of Cu added to soils that made tomato shoot biomass down to 50% ,were increased significantly in leached soils,especially the three soils high in organic carbon and the two soils high in salinity. Partial correlation analysis showed that soil pH was the most important factor controlling Cu toxicity to tomato growth. Stepwise multiple regressions showed that soil pH and organic carbon content could explain more than 80% of the variance for EC50 values in both leached and unleaehed soils. When taking into account the effect of soil clay content in unleached soils or the effect of cation exchange capacity in leached soils on EC50 values, determination coefficients （R2） of the regression models were increased up to 0. 862 and 0. 891, respectively. Findings of the experiment demonstrate that it is proper to use some soil properties,like pH, organic carbon content, clay content or cation exchange capacity as indicators to predict the toxicity of extraneous copper in the soil to tomato growth.