Effects Of Allelopathy And Arbuscular Mycorrhizae In The Invasion Of Solidago Canadensis L.

Biological invasions especial the plant invasions are ubiquitous in the nature and the mechanisms of invasion are also diversity. The invasive plants can enhance their competitiveness by changing their traits and the allelopathy which can inhibit the growth of neighbor plants can also be used as the new weapon in the process of invasion. Moreover, the invasive plants would take the advantage of the arbuscular mycorrhizal fungi to improve its invasion. Solidago canadensis L. is a typical invasive plant in southeastern coastal areas of China. It has been studied that the S. canadensis has strong allelopathy on others and can establish the mutualism with AMF. However, the variation of competitiveness of S. canadensis since its invasion in China and how the allelopathy and AMF affect its invasion and growth is less well known at present. In this paper, I designed two common garden experiments and one control experiment, made a biogeography comparison about the competitiveness and allelopathy of S. canadensis, and studied the effect of AMF and allelopathy on the growth of S. canadensis and the selection effect of S. canadensis on AMF by secreting allelochemicals. The main results obtained from these experiments are as follows:1The change of competitiveness of S. canadensis since it’s invade in ChinaThe S. canadensis populations from different origins have different plant height and biomass. The plant height and biomass of populations from China are respectively15%and23%higher than the populations from USA. Furthermore, the populations from China have stronger competitiveness to Kummerowia striata than the populations from USA.2The change of the allelopathy of Solidago canadensis to plant since it’s invade in ChinaThe relative interaction index rate(RII) of K. striata when plant with Chinese and American S. canadensis on the condition of activated carbon are respectively-48.34±7.06%and-45.55±6.99%, which indicated the same inhibitory effects between China and USA. When the allelochemicals are restored, the inhibitory effects on K. striata are all improved both Chinese S. canadensis populations and American populations, but the Chinese populations are stronger than American populations whose Rll attained-68.82±5.37%. The inhibitory effect on S. canadensis of K. striata is improved when the allelochemicals were screened.3The effects of allelochemicals on the infection effect of AMF on S. canadensisThe colonization rate of AM of Chinese and American S. canadensis are respectively52.30±1.91%and50.40±1.70%when the allelochemicals is existence but38.13±0.77%and37.67±1.71%when the allelochemicals is screened.4The effects of allelopathy and AMF on the growth of S. canadensisThe biomass of S. canadensis is lowest both Chinese populations and American populations when the allelochemicals is existence while the AMF is inexistence. It is improved when the AMF is inoculated in the soil and more improved when the allelochemicals is screened while the AMF is inoculated. The tendency of K. striata is not obvious.5The effects of allelochemicals on the activity of AMF that advantage to S. canadensis and K. striataThe allelochemicals which were secreted by S. canadensis have negative effects on the activity of AMF of K. striata but positive effects on itself. So it can indirectly inhibit the growth of K. striata and promote the growth of itself.