Abstract:

In order to discuss the utilized efficiency of N and P by Sargassum portulacastrum . The preliminary study on the uptake rates of N and P by Sargassum fusiforme at the different concentrations、and different chemical combination of N and P were made under laboratory conditions. The results showed that: (1) At the suitable levels of concentrations, the uptake rates of N and P by Sesuvium portulacastrum’s increased with the increase concentrations of N and P in the media, and it was significantly different(P<0.05). When the N concentrations were at 100 μmol/L, uptake rates of N by Sesuvium portulacastrum reached the maximum value, and the maximum value was 11.11 μmol/g?d; when the P concentrations were at 10 μmol/L, the uptake rates of P by Sesuvium portulacastrum also reached the maximum value, the maximum value of P was 0.74 μmol/g?d. (2) At the different ratios of N to P and different N concentrations, the average uptake rates of N were not significantly different except at the ratio 1:1 and 5:1(P<0.05); but at the different ratios of N to P and different N concentrations, the average uptake rates of P were significantly different(P<0.05). The maximum uptake rates of N by Sesuvium portulacastrum occurred at the N concentrations of 50μmol/L and the ratios 50:1(N:P); and the maximum uptake rates of P by Sesuvium portulacastrum occurred at the N concentrations of 50 μmol/L and the ratios 10:1(N : P). (3) The uptake rates of NH4+-N by Sesuvium portulacastrum increased with the reduction ratios of NH4+-N and NO3－-N, while the uptake rates of NO3－-N by Sesuvium portulacastrum decreased with the reduction ratios of NH4+-Nand NO3－-N, and they all were significantly different(P<0.05). The trend of the uptake rates of TIN and PO43--P were broken line. The maximum uptake rates of TIN occurred at the ratios1:2(NH4+-N: NO3－-N), and the maximum uptake rates of PO43--P occurred at the ratios1:10(NH4+-N: NO3－-N).