| Allelopathy was defined as a process involving secondary metabolites produced by plants, micro-organisms, viruses, and fungi that influences growth and development of biological systems. The allelopathy may be so striking that competition for resources does not explain why, in plant communities, many species appear to regulate one another through the production and release of chemicals, stimulators or inhibitors. It is in the nature extensive existence, it have the more important function in plant communities succession, the vegetation instauration and agriculture, forestries production. Allelopathy is a new marginal area of research , being common valued by the ecologists and chemists in recent years.Artemisia scoparia, an annual or biannual herbaceous plant with strong smell, is widely distributed in fields, roadsides and wastelands in China. It can be observed in the symbiotic communities of A. scoparia and other plants, A. scoparia always is dominance, sometimes in the communities that the A. scoparia concentrated growth, the growth of other plants is subjected to the inhibition.It produced bigger harmfulness to the natural vegetation, agriculture. The purpose of this study is to investigate whether the allelopathy have some function in the formation and successions of A. scoparias communities .For the first time,in this paper the allelochemicals and allelopathy of A. scoparia were studied completely, the mechanism of A. scoparia allelopathy on plant communities succession, the vegetation instauration was studied.It's allelochemical and slow release carrier was synthesized.It can provide scientific evidence for chemical ecology research of A.scoparia community and it's allelopathic application.The studies have the following conclusions:1. An important path of higher plant releasing allelopathic substances is volatilization. The A. scoparia contains abundant of volatile oil.Through vapor distillation and extraction method, essential oil could be obtained. In order to study the allelopathy of A. scoparia volatile oil , Raphanus sativus,Medicago sativa,Brassia pekinensis,Zea mays were used as receptor to study the effects of volatile oil on the seed germination and the growth of roots and seedlings, The results showed volatile oil has different inhibition effects on seed's germination and seedling growth of R. sativus, M. sativa, B. pekinensis and Z.mays. The germination of R. sativus seeds treated with the volatile oil was 27.3% than the untreated seeds. Root and seedling growth of M. sativa were strongly inhibited too, reduced 19.2% and 33.4% than untreated seeds. The inhibition on Z.mays was not obvious. It is proved that the different families plants have different resistance to allelochemicals.The main compositions of volatile oil is usually terpene compounds. The terpene compounds are usually important allelopathic substance. In this study the compositions of A. scoparia volatile oil were analyzed, there were 12 kinds of terpene compounds, which were the main components and constituted 45.04% of the total mass from volatile oil. In natural plant community, the reason of A. scoparia extensive rampanting is various, in addition to it has the physiological characteristic of stronger breeding ability and bearing drought and having flourishing root system, the inhibition function of chemical compositions in the plant to other plants is one of the important reasons. We also studied the effect of volatile oil of Artemisia scoparia poisoning insects, revealed the chemical relationships between Artemisia scoparia and some other organisms, which can provide scientific bases for developing botanic pesticides without social effects of pollution and rationally utilizing Artemisia scoparia resources.2. The aqueous extracts of A. scoparia affect seed germination and seedling growth of receptor plants. The effects are different on different receptor plants, even on different parts of one plant. There are more inhibitive effects on Medicago sativa ,Kochia scoparia , Amaranthaceae retroflexus than Leymus Chinese, Echinochloa crusgali,and seedling length than root length .The effect is stimulative when the concentration is 0.002g·ml-1, gradually decreased , is appeared and even changed into suppressive effect when the concentration is higher than 0.05 g·ml-1.3. Four different concentrations (0.15 g·ml-1,0.10 g·ml-1,0.05 g·ml-1,0.01 g·ml-1 (DW/V)) and different organs of A. scoparia were used to study it's mechanism on M. Chinese.The result shows that four different aqueous extracts have inhibition on M. Chinese,the effect of inhibition is increased with the concentration. The aqueous extracts of different organs have inhibition on M. Chinese,the effect of leave is stronger. The allelopathy of A. scoparia on M. Chinese is done through to affect the activity of protective-enzyme and photosynthesis.4.We used different stages ,different organs and four different concentrations (0.1g·ml-1,0.05g·ml-1,0.01g·ml-1,0.002g·ml-1 ) of A. scoparia aqueous extract to study it's allelopathy mechanism on M. sativa. The aqueous extract of A. scoparia affects dynamics of height , fresh weight of M. sativa .The activities of CAT,POD and SOD in M. sativa were enhanced to resist the of A. scoparia .The activities of CAT,POD and SOD gradually decrease when the concentration of the aqueous extract increases. The mechanism of the allelopathy is similar that the allelopathy of A. scoparia affects the activity of protective-enzyme of receptor plant and breaks the structure and function of membrane.5. The yellow volatile oil was gotten by the method of vapor distillation with a mean yield of 0.38% (V/DW). The volatile oil was analyzed with GC/MS.Thirty eight compounds were identified and constituted 87.53% of the total mass. There are 12 terpene compounds, which are the main components and constituted 45.04% of the volatile oil from A.scoparia. Allelochemicals of the aqueous extracts were extracted ,purified and analysed by GC/MS . Sample A mainly include phenol,terpene,alcohol,ester,organic acid .Two monomer allelochemicals were identified by nuclear magnetic resonance (NMR),B is 6,7-Dimethylesculetin (DE) ,C is di(2-ethylhexyl)phthalate(DOP).6. Because the content of allelochemicals is lower in plant,we hope to find a way getting a lot of allelochemicals. Chemical synthesization is an important way.We synthesized the Di(2-ethylhexyl)phthalate(DOP) by using p-toluene sulphonic acid as catalyst and proved it's allelopathy. We find a new pathway of obtaining allelochemicals through chemical synthesization.It is very important for deeper research and application of allelochemicals7. For the first time, we studied slow release technology on allelochemicals, polyaniline(PANI) dope with allelochemicals (gallic acid or ferulic acid )was prepared by using gallic or ferulic acid/PAM fibers template. The structure and morphology of the PANI were characterized by IR spectra, XRD patterns, and SEM images. The results indicated that the products were PANI doped with gallic acid or ferulic acid. And the morphology of the PANI nanorods with diameter in 200-300 nm was obtained. In addition, the new material can release allelochemicals (gallic acid or ferulic acid ) while environment pH is increased .It can improve the effect of allelochemicals in the process of application.
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