施氮量对矿山生态型粗齿冷水花磷富集特性的影响

采用土培试验,以矿山生态型粗齿冷水花为研究对象,非矿山生态型为对照,探讨了高磷(400 mg P/kg)处理下不同施氮量(0,70,140,210,280和350 mg N/kg)对矿山生态型粗齿冷水花磷富集特性的影响,为利用矿山生态型粗齿冷水花提取土壤中过量的磷,防治磷的非点源污染提供理论依据。结果表明,1)矿山生态型粗齿冷水花地上部和地下部的生物量、磷积累量均在140 mg/kg施氮量下达最大值;其中,矿山生态型地上部磷积累量为223.73 mg/株,非矿山生态型为159.79 mg/株。不同施氮量处理下,矿山生态型地上部生物量和磷积累量显著高于非矿山生态型。粗齿冷水花磷富集系数随施氮量增加逐渐升高,迁移率均高于50%,达到71%~88%。2)随施氮量增加,矿山生态型根系酸性磷酸酶活性逐渐升高,而植酸酶活性先升高后降低,在140 mg/kg达最大值。各施氮量下的矿山生态型根系酸性磷酸酶和植酸酶活性均显著高于非矿山生态型,分别为非矿山生态型的1.22~1.67倍和1.02~1.07倍。在70~210 mg/kg范围施氮有助于促进矿山生态型粗齿冷水花生长,增加植株对磷的积累,提高其富磷潜力。本研究条件下,140 mg/kg为最佳施氮量。

Effect of different levels of N supply on P accumulation characteristics of a ‘mining ecotype’ of Pilea sinofasciata

Quantities of P fertilizer and organic fertilizer are supplied in agro-ecosystems to improve the soil a-vailable P content and maintain soil fertility,but ultimately resulting in P immobilization and accumulation in the soil.Phytoextraction is a practical method for recovering the excess P after soils have become enriched.In order to provide a theoretical basis for extracting excess P from soil to assist with prevention and control of non-point source pollution,it was necessary to determine the P accumulation characteristics of a ‘mining ecotype’ (ME)of Pilea sinofasciata .This material had previously been screened as showing promise for P extraction from enriched soil.The effects of different levels of nitrogen (N)supply (0,70,140,210,280,350 mg N/kg)on plant growth and P accumulation characteristics in the ME of P .sinofasciata were analyzed,with a non-mining ecotype (NME)as contrast.All treatments had the same P supply (400 mg P/kg soil).Pot experi-ments were carried out in a greenhouse at Sichuan Agricultural University,Sichuan province,China in 2013. Key results were:1)For both shoot and root biomass,P accumulation of P .sinofasciata significantly increased
with increased N supply up to 140 mg/kg,and then decreased with additional N supply.Shoot P accumulation of the ME was maximized at 140 mg/kg N supply,and ME demonstrated greater shoot P accumulation (223.73 mg/plant)than the NME (159.79 mg/plant)under different rates of N supply.The bioaccumulation coeffi-cient of the ME was more than 1,while translation rate was more than 50%,and as high as 71%-88%.2) The activities of acid phosphatase and phytase in P .sinofasciata peaked at N application rates of 350 mg/kg and 140 mg/kg,respectively,and the activities of these two enzymes in the ME were markedly higher (P <0.05)than those in the NME,being increased by a factor of 1.22 -1.67,and 1.02 -1.07,respectively.In conclusion,the P .sinofasciata ME showed substantial P accumulation ability under N application rates of 70-210 mg/kg.Thus,P .sinofasciata is a good candidate species for P phytoextraction,with the best results ob-tained when N was added at 140 mg/kg soil.