The Effects Of Dodecane On The Vegetative Growth,Photosynthetic Pigments And Antioxidative Enzymes Of Salvinia Natans (L.) All.

Salvinia natans (L.) All. is a free-floating fern distributed mainly in static aquatic habitats. It has a strong accumulation capacity of metals from pollution water. It also can accelerate the transformation of nitrogen and phosphorus from eutrophic water. Therefore, it can availably restore waste water polluted by metals or nutrition. In this paper, static toxicity testing method was used to research the effects of dodecane on the physiologic characteristics and vegetative growth of S. natans. Some results had gained as follows:1. The mortality of S. natans was closely related to the concentration of dodecane and treatment time, most of the total death occurred before day4.2. Dodecane pollution had serious effects on the growth of floating leaves, buds and submerged leaves of S. natans. Dodecane could significantly inhibit the growth of new floating leaves of S. natans, the higher of dodecane content, the greater of the effects. It could also speed up the floating leaves to turn yellow, the number of yellow leaves positively related to concentration of dodecane. Dodecane could significant inhibit the formation of apical buds. Therefore, it has a significant effect on the development of branches, and the effect of low concentration would weaken along with the treatment time. High concentration of dodecane could significant inhibit the formation of apical buds and affect the further growth and asexual reproduction of S. natans. Biomass accumulation of floating leaves showed a significant negative linear correlation with the concentration of dodecane, while growth of submerged leaves had not been affected by dodecane contrasted to floating leaves.3. Dodecane pollution could significant affect the photosynthesis of S. natans. The area of floating leaves showed a significant negative linear correlation with the concentration of dodecane, so dodecane could significantly reduce the photosynthetic area of S. natans. In the earlier stage of the experiment, dodecane could also significantly promote the degradation of chlorophyll (including chlorophyll a, chlorophyll b) in floating leaves, so it can inhibit the photosynthesis of S. natans.4. Dodecane pollution also had a profound impact on the antioxidant enzyme systems of S. natans. In the earlier stage of the experiment, dodecane could significantly promote the activity of superoxide dismutase, catalase and peroxidase, but inhibit the activity of ascorbate peroxidase. Dodecane could also induce membrane lipid peroxidation of S. natans and accelerate it to senescence and death. 5. Dodecane didn’t show obvious effects on the pH value and water conductivity of culture mediums.From the results we know that dodecane could significantly affect the vegetative growth of S. natans, and impact the photosynthesis and antioxidant enzyme system. Because of the high sensitivity to dodecane, S. natans could be used as an indicator for dodecane pollution in aquatic environments. Especially the activity of superoxide dismutase and ascorbate peroxidase could be useful biomarkers to evaluate water pollution by dodecane.