Abstract:

To investigate physiological responses of Ulva linza to addition of N and P and its mechanisms,an experiment was conducted culturing Ulva linza in solutions different in N and P concentration for 10 days and then relative growth rate (R_r,g),contents of N,P,chlorophyll (Chl) and carotenoid (Car),Chl a/Chl b,Chl/Car and chlorophyll fluorescence parameters(CFP) were determined. Results show that in the solutions kept the same in P concentration (30 μmol·L^-1P),with rising N concentration,all the indices of the algae gradually increased except for P content which declined steadily,and both Rr,gand CFP peaked and when N content reached 500 μmol·L^-1,and Chl,Car and Chl a/Chl b did when N content reached 1 000 μmol·L^-1. However,in the solutions kept the same in N concentration (500 μmol·L^-1N),rising Pconcentration did not affect R_r,g or N content in the algae much,however,it did increase P content significantly in the algae,while the other indices varied just slightly. To sum up,compared with P,N is more important to growth,formation of photosynthetic pigment and photosynthesis of Ulva linza. In the solution with 500 μmol·L^-1N and 30 μmol·L^-1 P ( N/P 16. 67),U. linza grows the most healthily and when the water body is getting eutrophied,U. linza N and P enrichment capacity rises steadily,too.