Effects of salinity, light and temperature on growth rates of two species of Gracilaria (Rhodophyta)

Effects of temperature, salinity and light intensity on growth rates of Gracilaria lichenoides and G. tenuistipitata var. liui Zhang et Xia were tested. Eight to ten levels of each factor were first tested separately. The best growth rate was obtained under the conditions of 32A degrees C, 30 and 240 mu mol/(m(2)center dot s) for G. lichenoides, and 24A degrees C, 20 and 200 mu mol/(m(2)center dot s) for G. tenuistipitata, respectively. Then a uniform design was used to evaluate the optimal combinations of the three factors. The best conditions for the highest daily specific growth rates (% increase in wet weight) are determined to be 31.30A degrees C, 32.10, and 287.23 mu mol/(m(2)center dot s) for G. lichenoides (16.26%/d), and 25.38A degrees C, 21.10, and 229.07 mu mol/(m(2)center dot s) for G. tenuistipitata (14.83%/d), respectively.