锌胁迫对互花米草生长、金属累积和有机酸变化的影响

Effects of zinc stress on growth,metal accumulation and organic acids changes of Spartina alterniflora Loisel

研究互花米草在不同锌处理条件下(250mg·kg^(-1)和1 000mg·kg^(-1))的生长状况和物理参数的变化.研究结果显示,当锌浓度为250mg·kg^(-1)时,可以提高植物分蘖密度.在锌胁迫条件下,叶绿素含量显著下降.相反,电解质渗透率、丙二醛、脯氨酸和可溶性糖却在增加.当锌浓度为250mg·kg^(-1)时,叶、茎、根状茎和细根的生物量都有所增加,但当锌浓度为1 000mg·kg^(-1)时,其生物量却被抑制.互花米草中总锌、水溶性锌和水溶性锌/总锌都随着锌处理浓度的增大而增大.草酸和枸橼酸是互花米草中含量最多的两种酸,在叶片和细根中,草酸和锌的富集呈正相关.在互花米草的叶片中,有机酸(抗坏血酸和富马酸)和锌的生物富集之间存在正相关关系.因此,有机酸(包括草酸、抗坏血酸、富马酸)可能在互花米草叶片中的锌富集和解毒作用中起到重要作用.而且,草酸可能和细根中锌的固定和锌从互花米草地下部分到地上部分的转移过程有紧密的关系.

Growth and physical parameters were investigated under different zinc treatments （250 mg kg-1 and 1 000 mg kg -1 ） in pot-cultured Spartina alterniflora. The results showed that plant tiller density was increased when treated with 250 mg kg -1 zinc concentration. Chlorophyll content decreased significantly under Zn stresses. Electrolyte leakage rate, MDA, proline, and soluble sugar increased, reversely. Leaf, stem, rhizome, and fine roots were all promoted under Zn concentration of 250 mg kg-1 , but the growth was suppressed when restrained by 1 000 mg kg- 1 Zn treatment. Total Zn, water-soluble Zn, and water-soluble Zn/total Zn in S. alterniflora increased with increasing Zn treatment concentrations. Oxalic and citric acids were the two most abundant acids in S. alterniflora, and oxalic acid and zinc bioaccumulation were positively related in leaf, and fine roots. There were positive relationships between organic acids （ascorbic and fumaric acids） and Zn bioaccumulations in leaf of S. alterniflora. We concluded that organic acids （including oxalic, ascorbic and fumaric acids） might play an important role in zinc accumulation and detoxification in leaf of S. alterniflora. And oxalic acid might be closely related to Zn sequestration in fine roots and Zn transfer from underground to aboveground part of S. alterni flora.