| In order to evaluate the injury and inherent physiological mechanism of glutaraldehyde stress on advanced aquatic organisms, Hydrilla verticillata was cultivated in 1/20 Hoagland solution with 0 mg·L-1, 1 mg·L-1, 5 mg·L-1, 10 and 50 mg·L-1 glutaraldehyde. Chlorophyll content, photosynthetic rate, antioxidase（SOD, POD and CAT） activity and MDA content were measured. The results showed that with the increase of concentration of glutaraldehyde and the extension of stress time, the content of chlorophyll a and chlorophyll b declined and the photosynthetic rate dropped. Under the treatment of 1 mg·L-1 or 5 mg·L-1 glutaraldehyde for 1 day and 3 days, SOD activity increased. But at 10 mg·L-1 or higher concentration of glutaraldehyde, it was significantly lower than that of the control. POD activity increased significantly under the treatment of 1 mg·L-1, 5 mg·L-1 and 10 mg·L-1 glutaraldehyde for 1 day and 3 days, but when the stress time extended to 5 days, it showed an absolute dropping even at low concentration of 1 mg·L-1 glutaraldehyde. At a general level, during all treatments, CAT activity showed a higher level under 1 mg·L-1 glutaraldehyde, but 5 mg·L-1 or higher concentration of glutaraldehyde stress made CAT activity lower than that of the control. MDA content remained almost unchanged in 1 day stress of all glutaraldehyde concentrations. However, when the stress time prolonged to 3 days and longer, it showed a rising tendency as the glutaraldehyde concentration increased. Generally, the results showed that antioxidase activity of H. verticillata was stimulated by low concentration of glutaradehyde but declined with higher glutaradehyde concentration and prolonging stress time. It′s worth noting that CAT activity did not decline with the treatment of 1 mg·L-1 glutaraldehyde for 7 days, suggesting CAT might be more tolerant to low content of glutaraldehyde than SOD and POD. |
