2种水生植物根际溶液磷素时空变异及有机酸分泌

利用根际土壤溶液的原位抽提和微量样品分析技术,比较了喜旱莲子草(Alternanthera philoxeroides)和香蒲(Typhalatifolia)2种水生植物根际土壤溶液磷素含量的时空变异和根系分泌有机酸种类及数量的差异,从植物吸收磷素、根系分泌有机酸和根际土壤pH值变化等角度探讨了植物磷素高效净化的根际调控机制.结果表明,2种水生植物的根际溶液磷素含量均明显低于非根际溶液;喜旱莲子草的根际溶液磷酸根离子质量浓度(2.53 mg.L-1)显著低于香蒲的根际溶液(5.43mg.L-1)(p<0.05),且喜旱莲子草根系对土壤溶液磷酸根的影响范围大于香蒲.与香蒲相比,喜旱莲子草分泌了较多的苹果酸(浓度27.33μmol.L-1),在活化土壤磷素、促进根系对磷素的吸收方面起了更大的作用.喜旱莲子草吸收磷素的根际效应强于香蒲.

In Situ Dynamics of Phosphorus in the Rhizosphere Solution and Organic Acids Exudation of Two Aquatic Plants

A mini-rhizotron experiment with Alternanthera philoxeroides and Typha latifolia was conducted to measure the spatial and temporal dynamics of phosphorus in the rhizosphere solution. The organic acids in the in situ rhizosphere soil solution were analyzed. A decreasing phosphorus concentration gradient in soil solution toward the root was observed for both A . philoxeroides and T. latifolia . The phosphorus concentration in the rhizosphere soil solution of A . philoxeroides (2.53 mg·L~(-1)) was lower than that of T. latifolia (5.43 mg·L~(-1) ) in the forth sampling day. Compared to T. latifolia , A . philoxerouies released more malic acid (27.33 μmol · L~(-1) ) which was more efficient in phosphorus mobilization. A . philoxeroides was more effective in phosphorus uptake in the rhizosphere than T. latifolia .