氮磷营养盐水平对灰化薹草浸泡液化感抑藻的影响

为了解不同氮、磷营养盐水平下植物化感作用对铜绿微囊藻生长的影响，以鄱阳湖洲滩优势植物灰化薹草为研究对象，在室内控温、控光无菌条件下，采用锥形瓶批式培养法，分别观测3组氮、磷营养盐水平〔5.0、0.5 mg/L（超富营养）；2.0、0.2 mg/L（富营养）；1.0、0.1 mg/L（中营养）〕条件下，灰化薹草质量浓度（以干质量计）为0（对照组）、0.05、0.1、1.5、3和6 g/L时，培养液中铜绿微囊藻细胞密度.通过对比分析铜绿微囊藻的生长曲线、最大比增长率和抑制率得到不同培养条件下铜绿微囊藻生长特征的差异.结果表明:在超富营养和富营养水平下，灰化薹草浸泡液对铜绿微囊藻的生长均呈现“低促高抑”现象，抑制率分别在-23.3%~26.1%和-10%~76.5%之间，由促转抑时灰化薹草质量浓度分别为3和1.5 g/L；而在中营养水平下抑制铜绿微囊藻生长，抑制率在1.6%~85.6%之间.铜绿微囊藻最大比增长速率随氮、磷营养盐水平表现为超富营养（0.81~0.88 d-1）>富营养（0.55~0.80 d-1）>中营养（0.40~0.76 d-1）.相同灰化薹草质量浓度对铜绿微囊藻的化感抑制作用，随氮、磷营养盐水平的增加而降低.3组氮、磷营养盐水平间最大比增长速率的差值，随灰化薹草质量浓度的增加而增大.研究显示，水体氮、磷营养盐对植物化感抑藻起着重要作用，因此利用植物化感控藻效果需综合考虑水体氮、磷质量浓度. 

Allelopathy Effects of Carex cinerascens Soaking on Microcystis aeruginosa under Different Concentrations of Nitrogen and Phosphorus

In order to determine the allelopathic effect of wetland beach dominant plants in Poyang Lake on the growth of Microcystis aeruginosa, variations in the growing status of M. aeruginosa under different culture conditions (indoor and sterile with control of temperature and illumination) were analyzed using the conical flask culture method based on the comparisons of growth curves, the maximum growth rates and inhibition rates. The experiments were conducted using Carex cinerascens, the dominant plant species in Poyang Lake, under the following conditions:the levels of N, P nutrients are 5.0, 0.5 mg/L (hypereutrophic); 2.0, 0.2 mg/L (eutrophic); and 1.0, 0.1 mg/L (mesotrophic) respectively. The content of C. cinerascens (dry mass concentration) was 0 (control), 0.05, 0.1, 1.5, 3 and 6 g/L separately. The results showed that under hypereutrophic and eutrophic conditions, C. cinerascens soaking solution exhibited the effect of 'acceleration at low contents and inhibition at high contents' on the growth of M. aeruginosa. The inhibition rates were ranged from -23.3% to 26.1% and from -10% to 76.5% respectively. At the switching point where the effect converts from acceleration to inhibition, the content of C. cinerascens was equal to 3 and 1.5 g/L respectively. At the mesotrophic level, C. cinerascens inhibits the growth of M. aeruginosa, and the inhibition rate was between 1.6% and 85.6%. The maximum growth rate of M. aeruginosa showed the following pattern with the change of the N, P nutrient level:hypereutrophic (0.81-0.88 d-1) > eutrophic (0.55-0.80 d-1) > mesotrophic (0.40-0.76 d-1). The allelopathic inhibition effect of the same content of C. cinerascens on M. aeruginosa weakens with increasing N, P nutrient level. The difference in the maximum growth rate among 3 groups of N, P nutrient level increases with an increase of the content of C. cinerascens. The outcomes revealed that the N, P nutrients in water play an important role in the mechanism of allelopathic inhibition, thus suggesting that further should take their effects into account when utilizing plant allelopathy to control algae.