The Effects Of Temperature, Light Intensity And Salinity On Halophila Ovalis Growth, Physiological And Biochemical Characteristics

The seagrass Halophila Ovalis, is a kind of marine submerged angiosperm, widely distributed and suitable for growing in subtropical shallow sea waters. At present, restoration research of Halophila Ovalis seagrass beds, which as the dominant species in subtropical, is almost blank in domestic. Aiming to study the effects of the temperature, light intensity and salinity on the seagrass, this experiment measured the chlorophyll-a, chlorophyll-b, total chlorophyll and carotenoid concentration, mass growth rate and the contents of soluble protein, malondialdehyde(MDA), as well as the activities of the Superoxide dismutase(SOD), Peroxidase(POD) and Hydrogen peroxidase(CAT) of leaves and rhizome respectively. Obtained the most suitable temperature, light intensity and salinity range for growth, and provided a certain amount of data and theoretical basis for the restoration and reconstruction technology of Halophila Ovalis. The experimental results are as follows:1. The effects of temperature on the growth of Halophila Ovalis were significant(P<0.05). When the temperature was at 20~30℃, all the indexes only except MDA which were determined are higher than in all the other treatments. And on this condition, the content of MDA is the lowest. Therefore, it can be determined the most suitable for the growth of temperature range is at 20~30℃.2. The impacts of light intensity on the growth of Halophila Ovalis were significant(P<0.05). At 80~120 μmol/(m2s), only the content of MDA is lower than other treatments. So the optimal light intensity for growth is at 100~120 μmol/(m2s).3. The influence of salinity on the growth of Halophila Ovalis were striking(P<0.05). At a range of 30~35, all indexes which were measured are higher than other groups except MDA. Hence the best fit salinity is at 30~35.4. Orthogonal experiment results show that the optimum factors and levels are 25℃,100 μmol/m2 s and 30. Under the condition of this level, all the indexes are much greater than those in other groups except MDA. By means of range analysis, founded that light is the main environmental factors on the growth and physiological and biochemical characteristics of Halophila Ovalis, followed by temperature and salinity.In conclusion, the most suitable temperature, light intensity and salinity range for growth are at 20~30℃,80~120 μmol/(m2s) and 30~35, respectively.