Effects of PEG simulated drought on the germination of Chimonanthus praecox seeds and the physiological response of seedlings to drought

The effects of simulated drought on seed germination and seedling physiological response of Chimonanthus praecox under different concentrations of PEG-6000 (0, 5, 10, 15, 20 and 25%) were studied. The results of the study showed that as the degree of drought intensified, the germination percentage, germination potential, germination index and vigour index of C. praecox seeds decreased significantly. When the PEG-6000 concentration was 25%, the C. praecox seeds no longer germinated. As the degree of drought increased, the SOD activity in the seedlings of C. praecox showed a trend of first increasing and then decreasing, while the activities of POD and CAT showed increasing and decreasing trends respectively; the contents of MDA, soluble sugar and soluble protein rose with the degree of drought going up. Correlation analysis showed that all the germination indicators of C. praecox seeds were extremely and negatively correlated with MDA, and SOD, POD activity, soluble sugar and soluble protein content were extremely significantly positively correlated with MDA content. Therefore, the seedlings of C. praecox under drought circumstances might increase the activity of SOD and POD, and enhance the content of soluble sugar and soluble protein to alleviate the oxidative stress and improve the adaptability of seedlings to drought.