Effect of high phosphate supply on P accumulation characteristics of mining ecotype of Polygonum hydropiper

In order to provide a theoretical basis for extracting the excess phosphorus(P) in soil or water, preventing non-point source pollution, it was necessary to determine the P accumulation characteristics in a mining ecotype（ME）of Polygonum hydropiper screened as P enrichment plant earlier, with a nonmining ecotype（NME）as contrast. Pot experiments were carried out in a screenhouse on the farm of Sichuan Agricultural University, Sichuan province, China in 2011. The effect of P-enriched treatment (P 800 mg/kg) on the characteristics of P accumulation in the ME of P. hydropiper at different growth periods（4 weeks, 8 weeks, 12 weeks）was analysed. 1）With growth period prolonged, the biomass of root, stem and leaf in the ME of P. hydropiper ascended and reached a maximum in 12 weeks at P-enriched condition. The increment of the ME was significantly higher than that of the NME additionally. Dry weight of root of the ME with P-enriched treatment was 4.50, 8.12 and 3.17 times compared with control at 4, 8 and 12 weeks respectively; and that of stem was 6.83, 11.47 and 15.14 times respectively; while that of leaf was 5.77, 10.49 and 7.11 times respectively. 2）Each organ of the ME with P-enriched treatment showed a significantly higher P concentration comparing with control, and the P concentration generally showed decreasing trend with the growth period prolonged. Bioaccumulation coefficient of the ME was more than 1; moreover, the ME was apparently higher than the NME. While its translocation rate was more than 50%, and the ME with P-enriched treatment was significantly higher which was 1.21, 1.21 and 1.20 times of the no phosphate treatment, respectively. Besides, P accumulation in root and shoot of the ME with P-enriched treatment reached 9.76 mg/plant, DW and 105.12 mg/plant, DW respectively, which were 2.29 and 3.29 times higher than the NME at 12 weeks. 3）Activity of acid phosphatase (Apase) in the ME reached its peak at 8 weeks. Compared with control, the ME was obviously higher, and it was significantly higher than that of the NME with P-enriched condition at 4 weeks and 8 weeks（P0.05）. Nevertheless, phytase activity in the ME gradually dropped with the growth period prolonged, while it showed higher with P-enriched treatment than that of control only at 12 weeks, and the ME was higher than the NME. The ME of P. hydropiper shows high absorption capacity and accumulation ability of P under P-enriched condition. Thus, it can be used as a kind of ideal and stable P enrichment material.