圆叶决明(Chamaecrista rotundifolia)对重金属镉胁迫的响应及镉吸收效果研究

Response to Cadmium Stress and Cadmium Uptake of Chamaecrista rotundifolia

以圆叶决明2228(Chamaecrista rotundifolia)为材料,采用土培法,研究重金属镉对圆叶决明2228保护酶(SOD和POD)、生长(生物量、株高、SPAD值和含水量等)的影响,同时分析圆叶决明对镉的吸收效果。结果表明,重金属镉胁迫下圆叶决明2228保护酶活性均随着镉处理浓度的升高呈先升后降的趋势,其中20mg·kg-1镉胁迫下SOD酶活性最强,50mg·kg-1镉胁迫下POD酶活性最强;镉对圆叶决明的生长抑制表现为抑制植物的生长,降低株高和生物量,但与叶绿素相关的SPAD值无显著变化。通过镉含量分析可知,圆叶决明2228吸收的镉量均未超过镉临界指标含量,因此该植物不是镉超富集植物,但生物富集系数大于1,为镉耐性植物。由于圆叶决明生长过程中生物量大,在生长过程中可通过生物量带走部分重金属镉,圆叶决明2228具有修复轻度镉污染土壤的潜能。

The objective of this study is to analyze the effect of cadmium（Cd） stress on cadmium uptake of the studied plant. Chamaecrista rotundifolia 2228,growing in plastic pots（d=25 cm）,was investigated in terms of changes of antioxidant enzymes（Super Oxide Dismutase,SOD and Peroxidase,POD）,and growth indices（biomass,plant height,chlorophyll content-SPAD value,and water content）. The results indicated that with increasing concentrations of applied Cd,the enzyme activities increased and then decreased. The strongest activities of SOD and POD were observed at a Cd stress level of 20 mg·kg^-1 and 50 mg·kg^-1,respectively. The results also showed that the presence of Cd significantly limited the growth of Chamaecrista rotundifolia 2228,implying by the reduced plant height and biomass,in comparison of the control. However,no significant change of SPAD value was identified at all levels of Cd stress. Cd contents of all the plants had never exceeded the critical value,which implied that Chamaecrista rotundifolia 2228 might not be a hyper-accumulator for Cd. However,the plant showed a substantial tolerance level to Cd as the bioaccumulation factor for most of the treatments was greater than one. A substantial amount of Cd could still be taken by Chamaecrista rotundifolia 2228 from the contaminated soil considering such high biomass values of the plant accumulated during the growing process. Clearly,Chamaecrista rotundifolia 2228 has a promising remedial potential for soils with a light or middle level of Cd contamination.