摘要
通过实验室静态模拟试验,研究了富营养状态下(N:4 mg/L;P:0.2 mg/L)不同比例硝态氮(NO3-_N)和尿素氮(Urea_N)(1∶0,2∶1,1∶1,1∶2)对苦草(Vallisneria atans)的生理影响.结果表明,硝态氮和尿素氮比例为1∶0,即以硝酸盐为唯一氮源时,苦草的生物量、可溶性总糖含量和硝酸还原酶(Nitrate Reductase,NR)活性明显高于其他处理组和无氮对照组,过氧化物酶(Peroxidase,POD)活性低于其他处理组和无氮对照组.随着培养液中尿素含量逐渐升高、NO3-_N:Urea_N比例降低,苦草的生物量、NR活性以及POD活性依次降低,苦草脲酶(Urease)活性逐渐升高,但当NO3-_N:Urea_N为1∶2时,苦草Urease活性受到抑制,明显低于其他比例组和无氮对照组.研究表明,添加一定量的硝态氮(硝态氮和尿素氮比例为1∶0,NO3-_N浓度为4 mg/L)可以促进苦草的生长,但当尿素含量逐渐增加时会对苦草产生一定的胁迫作用,硝态氮(NO3-_N)和尿素氮(Urea_N)对苦草产生胁迫影响的阈值比为1∶1,此时TN为4 mg/L,NO3-_N和Urea_N均为2 mg/L.
The physiological effects of different ratios of NO3ˉ -N to Urea-N （1 ： 0, 2 ： 1, 1 ： 1, 1 ： 2） on Vallisneria atans were investigated under eutropic nutrient condition in static laboratory experiment. The biomass, the soluble sugar contents, the activities of peroxidase （POD）, nitrated reductase （NR） and urease of Vallisneria atans were investigated. Results showed that the biomass, soluble sugar contents and activities of nitrate reductase （NR） of Vallisneria atans were significantly higher than those of other treated groups and the control group, the activity of peroxidase （POD） was much lower than other treated groups and the control group when NO3ˉ -N was the only source of nitrogen in culture solution （the ratio of NO3ˉ-N to Urea-N was 1：0）. By increasing the proportions of Urea-N in culturesolution and declining the ratios of NO3ˉ -N to Urea-N, especially when the ratio of NO3ˉ -N to Urea-N was lower than 2：1, the biomass, activities of nitrate reductase （NR） and peroxidase （POD） of Vallisneria atans decreased while the activities of urease increased gradually, but the activities of urease declined and were much lower than those of other treated groups and the control group when the ratio of NO3ˉ -N to Urea-N was 1 ： 2. The results indicated that the moderate concentration of NO3ˉ -Ncould accelerate the normal growth of Vallisneria atans, but the raised urea concentrations in water could be a stress to plants and influenced the normal growth of Vallisneria atans. The critical ratio value of NO3ˉ -N to Urea-N which may influence the normal growth of Vallisneria atans would be 1 ： 1, meanwhile the concentration of total nitrogen （TN） in cultured culution was 4 mg/L and the concentration of NO3ˉ -N and Urea-N was 2 mg/L respectively.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2005年第6期627-633,共7页
Journal of Nanjing University（Natural Science）
基金
国家重点基础研究发展规划(2002CB412307)
江苏省自然科学基金(BK2005082)
关键词
富营养
苦草
N素形态
生理影响
eutropic, VaUisneria atans, nitrogen form, physiological effect
