A Comparative Study On The Competitiveability Of Invasive Plant Xanthium Italicum Moretti And Native Plant X. Sibiricum Patr

Xanthium italicum Moretti is a therophyte herb of the Xanthium of the Compositae,which is a kind of malignant invasion plants.The plant is large in size,high in fruit weight,fast in growth,fast in propagation,strong in ecological adaptability,strong in invasion,and has caused vicious damage to the ecological system of the invading land.To study the competitive effects of different water conditions and nitrogen on X.italicum and X.sibiricum,this article adopts the method of replacing experiments,under controlled conditions by pot experiments in order to understand and reveal the internal mechanism of X.italicum invasion of natural conditions,it provides scientific basis for the management and control of invasive plant X.italicum.The results are as follows:(1)Water significantly promoted the growth of the X.italicum and X.sibiricum,significantly increased the leaf chlorophyll content,leaf area,total biomass,root biomass,stem biomass and leaf biomass,fruit biomass and top-root ratio of X.italicum and X.sibiricum.In mixture,all indexes of X.italicum were significantly higher than that of X.sibiricum.Under different water conditions,X.italicum has a stronger response to water,and its competitive ability is better than that of X.sibiricum.(2)Nitrogen significantly promoted the growth of the X.italicum and X.sibiricum,significantly increased the leaf chlorophyll content,leaf area,total biomass,root biomass,stem biomass and leaf biomass,fruit biomass and top-root ratio of X.italicum and X.sibiricum.And there were increased with the increase of nitrogen level.In mixture,all indexes of X.italicum were significantly higher than that of X.sibiricum.Under different nitrogen conditions,X.italicum is more sensitive to nitrogen,and its competitive equilibrium index is significantly greater than 0,which is more competitive than X.sibiricum.(3)There is a certain degree of negative interaction between above and belowground competition between the X.italicum and X.sibiricum.The X.italicum is affected by the above and belowground competition which results in significant positive interaction,while the X.sibiricum is affected by the above and belowground competition which results in significant negative interaction.Under the conditions of ground and underground isolation,the competitive power of X.italicum is greater than X.sibiricum.