中文摘要：

为了探讨水葫芦净化富营养化水体过程中根系脱落物的氮磷释放对于水质的影响，在滇池草海水域，利用围栏控制性种养水葫芦，于2013年5～11月，每隔30d监测单元框内水葫芦生物量（鲜重）与干重，采集水葫芦样品测定植株氮磷含量；收集单元框内根系脱落物，并监测鲜重与干重及其氮磷含量。结果显示：（1）5—9月（旺盛生长期）和10-11月（逐渐枯萎期）的水葫芦植株干物质氮磷含量无显著差异（P〉0．05），但是旺盛生长期内水葫芦的生长速率明显高于逐渐枯萎期（P〈0．05），使得旺盛生长期内水葫芦对水体氮磷的净化效果明显优于逐渐枯萎期。（2）根系脱落物的鲜重仅占水葫芦鲜重增加值的7．72％；根系脱落物的干重仅占水葫芦干重增加值的2．10％，根系脱落物含氮量仅占水葫芦植株含氮量增加值的2．50％；根系脱落物含磷量仅占水葫芦植株含磷量增加值的3．05％。分析认为，与水葫芦植株从水体带走的氮磷量相比，随着根系脱落物降解释放而返回水体的氮磷量极少，不会对湖泊水质造成负面影响。

英文摘要：

In order to discuss the effect of the release of nitrogen and phosphorus from root exfoliation of water hyacinth （Eichhornia crassipes ） on water quality during the course of eutrophic water purification, water hyacinth was cultivated in confined fence facilities in the Caohai of Dianchi Lake. The plant and root exfoliation were collected every 30 days from May to November in the year of 2013, and fresh and dry weight as well as nitrogen and phosphorus contents were determined. The results showed there was no significant difference （P〉0.05） between May-Sep （rapid growth period ） and Oct-Nov （gradual withering period ） on the contents of nitrogen and phosphorus in dry matter of water hyacinth, while the growth rate of water hyacinth in rapid growth period was significantly （P〈0.05） higher than that in gradual withering period. As a result, the purification of nitrogen and phosphorus in water by water hyacinth was more evident in rapid growth period than that in gradual withering period. The fresh weight, dry weight, nitrogen content, and phosphorus content of root exfoliation only accounted for 7.72%, 2.10%, 2.50%, and 3.05% of the increment of fresh weight, dry weight, nitrogen content, and phosphorus content of water hyacinth, respectively. The results implied that compared with the amount of nitrogen and phosphorus taken out of the lake water by water hyacinth, the amount returned into the lake water through root exfoliation was much lower. Confined growth of water hyacinth in the lake exerted no nega- tive effect on the lake water quality.