EDDS对Cd胁迫下三叶鬼针草生长和抗氧化酶系统及Cd积累的影响

为探讨乙二胺二琥珀酸(EDDS)对镉(Cd)胁迫下三叶鬼针草(Bidens pilosa L.)生长和抗氧化酶系统及Cd积累的影响,采用盆栽实验,研究了40 mg·kg~(-1)Cd胁迫下,施加0(CK)、0.5、1.5、2.5 mmol·L~(-1)和5.0 mmol·L~(-1)EDDS后三叶鬼针草生长和抗氧化酶活性及Cd积累的变化。结果表明:施加0.5 mmol·L~(-1)和1.5 mmol·L~(-1)的EDDS利于三叶鬼针草幼苗的生长,株高、根长、地上部鲜干重和地下部鲜干重均显著增加;施加0.5、1.5 mmol·L~(-1)和2.5 mmol·L~(-1)EDDS使地下部(根)和地上部(茎和叶混合)组织中Cd含量均显著大于CK,且在1.5 mmol·L~(-1)时Cd积累量达到最大(分别为31.954 mg·kg~(-1)和109.454 mg·kg~(-1)),富集系数和转运系数也达到最大(分别为3.521和3.426);随施加EDDS浓度的升高,植物地下部和地上部组织中过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性呈现先增强后降低或持续增强的趋势,说明抗氧化酶系统被启动,以清除胁迫过程中积累的活性氧(ROS),缓解胁迫对植物造成的膜脂过氧化损伤。因此,施加适宜浓度的EDDS可促进三叶鬼针草幼苗的生长,增加三叶鬼针草对Cd的吸收和富集能力,有利于Cd污染土壤的修复,综合考虑螯合剂的成本以及对土壤造成的二次污染,宜选用EDDS的浓度为1.5 mmol·L~(-1)。

Effects of EDDS on growth, antioxidant enzyme, and Cd accumulation of Bidens pilosa L. seedlings under Cd stress

A pot experiment was conducted to study the effects of adding 0(CK), 0.5, 1.5, 2.5 mmol·L^-1, and 5.0 mmol·L^-1 ethylenediamine disuccinic acid(EDDS) on growth, antioxidant enzyme activities, and Cd accumulation in Bidens pilosa seedlings under 40 mg·kg^-1 Cd stress. The results showed that the dry and fresh weight, plant height, and root length of the seedlings were promoted significantly by treatments with 0.5 mmol·L^-1 and 1.5 mmol·L^-1 EDDS. The belowground(roots) and aboveground(stems and leaves) parts had significant higher level of Cd accumulation in the 0.5, 1.5 mmol·L^-1, and 2.5 mmol·L^-1 EDDS treatments than that in the CK, but the concentration of 1.5 mmol·L^-1 showed the best effect, with the maximum value of 31.954 mg·kg^-1 and 109.454 mg·kg^-1 in the belowground and aboveground parts, respectively. The highest bioaccumulation factor(3.521) and the highest translocation factor(3.426) were also observed in the 1.5 mmol·L^-1 EDDS treatment. With increasing EDDS concentration, activity of catalase(CAT), ascorbate peroxidase(APX), glutathione reductase(GR), peroxidase(POD) and superoxide dismutase(SOD) in the belowground and aboveground parts of Bidens pilosa seedlings under Cd stress appeared to present an initial increasing trend, followed by a decrease or persistent increase. These findings indicated that the antioxidant enzyme system was activated to eliminate reactive oxygen species(ROS) and alleviate membrane lipid peroxidation damage induced by Cd stress. The present results suggested that an appropriate concentration of EDDS could promote the growth of seedlings under Cd stress and increase the capacity for absorption and accumulation of Cd, which is beneficial for the remediation of Cd-contaminated soil. Taking into account the cost of chelating agent and secondary soil pollution caused by the chelating agent, the appropriate concentration of EDDS was found to be 1.5 mmol·L^-1.