Study On Allelopathy And Its Mechanism Of Artemisia Annua L.

Compositae is the biggest and the most evolutional family of angiosperme. It contents most natural components and offers ideal donor plants for the studies on allelopathy. We have studied allelopathy of 10 species of Compositae plants worked on wheat, and found Artemisia annua L. strongly retarded wheat seedling growth. For further studies, we discussed allelopathy actions and its mechanisms of Artemisia annua L. The main results were as follows.1. Indoor Petri dish bioassay was adopted for studying the allelopathy of Artemisia annua L. worked on seed germination of wheat, cabbage, rape and ryegrass. The results showed that aqueous extracts of Artemisia annua L. could delay seed germination, reduce germination rate of rape and ryegrass. The aqueous extracts promoted seed germination rate of wheat and cabbage at low concentration but inhibited it at high.2. Study on allelopathy of Artemisia annua L. showed that its aqueous extracts restrained the growth of the test plants, and this inhibition became stronger when the concentration of the extract solution was higher. However, during the latter period of treatment, action of lower concentration on rape and ryegrass seedling turned to promotion. The root was more sensitive to aqueous extracts of Artemisia annua L. than seedling, and seedling stage was more sensitive than germination stage.3. Micro-observation on wheat roots showed that aqueous extracts of Artemisia annua L. restrained mitosis and cell enlongation. And the structure of root altered at high concentration. The outgrowth of root hair and new roots were inhibited.4. We mensurated some physiological and biochemical indexes of treated wheats. The results showed that with the concentration of the extraction solution rose, the activity of SOD, POD and CAT in vivo first increased and then decreased. The extract solution of Artemisia annua L. increased the content of MDA, but decreased the content of chlorophyll, nucleic acid, soluble protein and soluble sugar. It also reduced the activity of root and amylase.