[Effect of environmental factors on N and P uptake by Gracilaria tenuistipitata var. liui Zhang et Xia].

The effect of light intensity, pH, temperature, salinity on the uptake of nitrogen and phosphorus by Gracilaria tenuistipitata var. liui Zhang et Xia was were studied under laboratory conditions. The uptake rate of nitrogen reached as high as 0.32-0.36 mumol.g-1.h-1 at favorable light intensity of 800-2400 mumol photon.m-2.s-1, while that of phosphorus reached 0.017-0.018 mumol.g-1.h-1 at 320-1600 mumol photon.m-2.s-1. The nutrient uptake rate reached the maximum at pH 8.0. A significant difference of N uptake rate at different temperatures or salinities and that of P uptake rate at different temperatures were found. The N uptake rate was higher at 21-26 degrees C and 20@1000-28@1000, but P uptake was higher at 21-26 degrees C. There was no interaction between temperature and salinity.