摘要
Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the elongation of roots although the length of seedlings exposed to Cd and Ph at 0.05 and 0.5 mg/L showed to be slightly greater than that of controls. Of the four metals in the experiment, Ph was absorbed and accumulated to the highest level, with the concentrations of 92754 mg/kg dry weight (DW) in roots and 11683 mg/kg DW in shoots. Cd was moderately accumulated in Agrogyron elongatum, but the maximum bioaccumulation coefficients (BCs) for roots and shoots were observed. The patterns for Cu and Ni uptake and distribution in plants differed from those of Ph and Cd, as it was showed that the shoot accumulation of Cu and Ni was significantly higher than in roots. A. elongation had the highest Ni concentration in shoots (30261 mg/kg DW) at the external concentration of 250 mg/L. Cu ranked second, with a shoot concentration of 12230 mg/kg DW when 50 mg/L Cu in solution was applied. For the four trace elements tested, the highest concentrations in shoots decreased by the order of Ni > Cu > Ph > Cd (mg/kg DW), and those in roots were Ph > Cd > Ni > Cu (mg/kg DW). Malic, oxalic and citric acids exuded by roots exposed to 1 and 50 mg/L of the metals were detected. Release of organic acids from plants significantly differed among the metal treatments. Cu was most effectively in inducing root exudation of the three types of organic acids. Cd, and Ni were also the inducers of secretion of malic and oxalic acids. With reference of Pb, a small amounts of malic and oxalic acids were detected in the root exudates, but few quantities, of citric acid were. found. However, no correlation between alternations in root exudation of organic acids and metal accumulation could be established.
Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the elongation of roots although the length of seedlings exposed to Cd and Ph at 0.05 and 0.5 mg/L showed to be slightly greater than that of controls. Of the four metals in the experiment, Ph was absorbed and accumulated to the highest level, with the concentrations of 92754 mg/kg dry weight (DW) in roots and 11683 mg/kg DW in shoots. Cd was moderately accumulated in Agrogyron elongatum, but the maximum bioaccumulation coefficients (BCs) for roots and shoots were observed. The patterns for Cu and Ni uptake and distribution in plants differed from those of Ph and Cd, as it was showed that the shoot accumulation of Cu and Ni was significantly higher than in roots. A. elongation had the highest Ni concentration in shoots (30261 mg/kg DW) at the external concentration of 250 mg/L. Cu ranked second, with a shoot concentration of 12230 mg/kg DW when 50 mg/L Cu in solution was applied. For the four trace elements tested, the highest concentrations in shoots decreased by the order of Ni > Cu > Ph > Cd (mg/kg DW), and those in roots were Ph > Cd > Ni > Cu (mg/kg DW). Malic, oxalic and citric acids exuded by roots exposed to 1 and 50 mg/L of the metals were detected. Release of organic acids from plants significantly differed among the metal treatments. Cu was most effectively in inducing root exudation of the three types of organic acids. Cd, and Ni were also the inducers of secretion of malic and oxalic acids. With reference of Pb, a small amounts of malic and oxalic acids were detected in the root exudates, but few quantities, of citric acid were. found. However, no correlation between alternations in root exudation of organic acids and metal accumulation could be established.
基金
ResearchGrantCounciloftheHongKongSpecialAdministrativeRegion
China(No .HKBU2 0 43 98M)andtheNationalNaturalScienceFoundation
