不同氮源对菹草生长和水质的影响

Effects of Different Nitrogen Sources on the Growth of Potamogeton crispus and Water Quality

【目的】研究在富营养条件下不同氮源对菹草(Potamogeton crispus)生长及水质的影响,旨在预防氮肥对水体生态系统的破坏。【方法】将备用菹草分成2组栽种,第1组按0.2、0.4、0.6、0.8、1.0 mg分别加入氯化铵,第2组按同样梯度加入尿素。每6 d取一次样,监测水体各项水质指标(pH、DO、氨氮和硝态氮)及菹草的生理指标(叶绿素a和可溶性糖)。【结果】氮源浓度越大,菹草叶绿素a含量越少;尿素组0.8 mg/L和1.0 mg/L试验组可溶性糖含量显著低于氯化铵组(P<0.05);氯化铵浓度越高,水体pH值越低,而尿素浓度越高,pH值越高;尿素组0.8 mg/L和1.0 mg/L试验组氨氮含量显著高于氯化铵组(P<0.05);氯化铵组硝态氮含量显著高于尿素组(P<0.05)。【结论】低浓度尿素更适宜菹草生长,高浓度氯化铵和尿素均抑制菹草生长。

【Objective】The aim of the study was to explore the influences of different nitrogen sources on the growth of P.crispus and water quality and to reveal potential damage of nitrogen fertilizer to water ecosystem.【Method】Theexperimentincludedtwogroups.Onegroupwasadded0.2,0.4,0.6,0.8 and 1.0 mg ammonium chloride,respectively.Another group was added with urea at the same rate.Water quality indices(pH,DO,ammonia nitrogen and nitrate nitrogen)and physiological indexes of P.crispus(chlorophyllaandsoluble sugar)weremeasuredevery6days.【Result】The content of chlorophyll a decreased with increasing nitrogen concentration.The content of soluble sugar under the 0.8 mg/L and 1.0 mg/L urea was significantly lower than those of ammonium chloride treatments(P<0.05).The pH value of the water declined with an increase in ammonium chloride.However?the opposite was true for urea treatment.The content of ammonia nitrogen under the 0.8 mg/Land 1.0 mg/L urea treatment was significantly higher than that of ammonium chloride treatment(P<0.05).The nitrate content under the ammonium chloride treatment was significantly higher than that of urea treatment(P<0.05).【Conclusion】Lowconcentration of urea was more favorable for the growth of P.crispus while high concentration of ammonium chloride and urea inhibited the growth of P.crispus.