绿萍对太湖地区稻田氮磷及水绵生长的影响

利用田间小区试验，研究了放养绿萍后对稻田水绵生长及田面水中N和P浓度变化的影响。在相同施肥水平下，绿萍处理的田面水中全N与NH4+-N浓度均低于无绿萍的处理。在分蘖期绿萍可调节土水中P的吸收与释放，减少了P肥损失的风险。此外，研究还发现施肥后的一段时间内，绿萍处理的田面水中叶绿素浓度变化较小，在20 ~ 45 mg/m3 之间，而不施绿萍处理的田面水中叶绿素浓度逐渐增加，3 ~ 5天后浓度就远远大于绿萍处理，达到了85 mg/m3，说明绿萍生长可有效抑制藻类的爆发。

Effects of Azolla on nitrogen, phosphorous and growth of Spirogyra sp. in flooded paddy field in Taihu aera

In this paper the effects of Azolla inoculation on the growth of Spirogyra sp. and the variation in concentrations of nitrogen and phosphorus in flood-water in paddy field were studied by a field experiment. Under the same level of fertilization, the concentrations of total nitrogen and ammonium nitrogen in flood-water with Azolla application were less than those without Azolla application. During the tillering stage, the assimilation and release of phosphorous in soil-water could be modulated with Azolla application, which reduced the risk of phosphorous loss. In addition, chlorophyll content in flood-water with Azolla application changed little, ranging from 20 mg/m3 to 45 mg/m3, in contrast, chlorophyll content without Azolla application increased gradually and was much higher than with Azolla application after 3 to 5 days, up to 85 mg/m3, indicating that the development of Azolla could inhibit algal bloom.