镉铅复合胁迫对桑苗生长与桑叶重金属含量的影响

Effect of Cadmium and Lead Combined Stress on Growth of Mulberry Saplings and Contents of Heavy Metal in Mulberry leaf

桑树是湖南重金属污染耕地替代种植的代表性植物之一。以桑品种湘桑6号、湘7920、农桑14号、粤桑11号为试验材料,人为添加不同浓度梯度的镉、铅进行盆栽试验,研究镉、铅复合胁迫对桑苗生长及桑叶重金属含量的影响。结果表明:桑苗株高、节距、最大叶幅随土壤中镉和铅含量的提高而降低,桑叶镉、铅含量与土壤镉和铅含量呈正相关;以桑叶产量减少25%时所对应的土壤重金属含量作为桑树对镉、铅胁迫的耐受值,在本试验条件下,桑树对重金属污染土壤中镉、铅的平均耐受阈值分别为40. 88 mg/kg和527. 00 mg/kg。

Mulberry tree has become one of the representative substitute plants for heavy metal contaminated farmland in Hunan Province.In this study,we investigated the effect of different concentrations of cadmium (Cd)and lead (Pb)on the growth and heavy metal contents in leaves of 4 mulberry varieties Xiangsang 6,Xiang 7920,Nongsang 14 and Yuesang 11 by pot experiment.Results showed that the height of mulberry saplings,leaf spacing and the maximum leaf width decreased with the increase of Cd and Pb content in soil.The contents of Cd and Pb in mulberry leaf were positively correlated with the heavy metal contents in soil.The experimental condition under which soil heavy metal contents corresponding to the leaf yield of mulberry decreased by 25% were used as the tolerance values of mulberry to cadmium and lead stress.Under this experimental condition,the average tolerance thresholds of mulberry trees to cadmium and lead in heavy metal contaminated soil were 40.88 mg/kg and 527.00 mg/kg,respectively.