田间条件下镉对番茄的毒害临界值研究

Toxic Effects of Exogenous Cadmium on Tomato and Its Toxicity Threshold

采用田间试验研究外源添加镉对镉敏感蔬菜——番茄幼苗根部（根长和根鲜重）和地上部（株高和茎叶鲜重）的毒害效应,计算镉对番茄的毒害临界值（EC10）,探讨了田间和盆栽条件下镉毒害临界值变化.结果表明：低浓度外源镉对番茄4个生长指标可能产生促进作用,而高浓度外源镉则产生抑制作用.不同土壤镉对番茄根长、株高及茎叶鲜重的毒害临界值（EC10,以土壤有效镉表示）差异较大,根长EC10值介于0.13～5.22 mg/kg,株高的EC10值介于0.14～9.34 mg/kg,茎叶鲜重的EC10值介于0.02～4.13 mg/kg.田间条件下所获取的番茄EC10值与盆栽条件下获取的EC10的比值,最大为103.25倍（C土,茎叶鲜重）,最小为2.85倍（C土,根长）,大部分情况下田间和盆栽试验的镉毒害临界值的差异小于5倍.部分情况下田间得到的EC10值大于盆栽试验得到的EC10值,而另一些情况下则反之.

The toxic effects of exogenous Cd on the length and the fresh weight of roots,and the height and the fresh weight of the aerial part of tomato,a Cd-sensetive crop,were studied by field experiments.The toxicity thresholds of Cd（EC10）for root length,plant height and the fresh weight of tomato were calculated based on the regression equations between soil available Cd（0.10 mol/L CaCl2 extractable） and root length,plant height and the fresh weight of aerial parts of tomato.The difference between the EC10 values derived from field experiments and those derived from greenhouse experiments were discussed.The results showed that low concentration of exogenous Cd may promote whereas higher concentration of exogenous Cd will inhibit the growth of tomato.The toxicity thresholds of Cd（EC10,expressed as soil available Cd） for root length,plant height and the fresh weight of aerial parts of tomato varied greatly in different soils.The EC10 values were 0.13 mg/kg to 5.22 mg/kg for root length,0.14 mg/kg to 9.34 mg/kg for plant height and 0.02 mg/kg to 4.13 mg/kg for the fresh weight of aerial parts.The maximum difference between the EC10 values derived from field experiments and from greenhouse experiments was 103.25 times for the fresh weight of aerial parts and 2.85 times for root length.At most circumstances,the difference of EC10 values from field experiments and greenhouse experiments was within 5 times.Some EC10 values from greenhouse experiments were higher than those from field experiments while the others were on the contrary.