Cultural conditions for Sargassum thunbergii germlings

Abstract:

To determine the suitable cultural conditions for the growth and development of Sargassum thunbergii germlings, three factors (illumination, temperature, salinity, each with three levels) orthogonal experiments and the nutrients experiments were carried out. The results showed that temperature on the special growth rate (SGR) of S. thunbergii germlings is the most significant (P<0.05). The maximum value of SGR was 10.87% when temperature was 25℃. But the SGR decreased gradually as the temperature dropped. Effect of salinity on the germlings SGR was significant (P<0.05). The germlings grew faster when salinity was 30, whereas the SGR decreased as salinity reduced. Effect of illumination (2,000~8,000lx) on the SGR was not significant and the range of SGR was close to the error. Nitrogen and phosphorus nutrients levels had great influences on the SGR of S. thunbergii germlings. The nitrogen concentration of the natural seawater used in the experiments basically met the requirements of the germlings growth; however, the phosphorus was relatively lacking. When N/P over 15:1, it was adverse to germlings growth and the suitable ratio was about 10:1~2:1. In conclusion, temperature 25℃, salinity 30 and illumination 2000lx were the suitable cultural conditions for S. thunbergii germlings. Cultural medium with nitrogen concentration of 0.45~1 mg/L and phosphorus concentration of 0.3 mg/L was suitable to the growth of S. thunbergii germlings.