Allelopathic Effects Of Alien Invasive Plants On Crops And Their Risk Assessment In Guan Zhong Region

In order to understand the influence of alien plant in Guanzhong (Yang lin) region and pretect local agriculture,we would study the allelopathic effects and their risk assessment of Erigeron annuus,Amaranthus retroflexus and Eleusine indica for main crops. By using the relay seeding technique,we studied the secretion of root system and different water extracts concentration of alien plant effcet on wheat (Triticum aestivum),rape (Brassica campestris ) and corn ( Zea mays ),The results showed:(1) The inhibitory of three alien plant effect on three receptor crops'seed were different.The allelopathic effect of water extract from alien plant seed roled in three receptor crops'seed,which had two forms,inhibiting and delaying germination.And the higher concentration,the stronger inhibitory.In a word,different alien plant had different inhibitory,to wheat and corn , Eleusine indica > Erigeron annuus > Amaranthus retroflexus,to rape,Eleusine indica> Amaranthus retroflexus >Erigeron annuus.(2) The inhibitory of three alien plant effected on three receptor crops'roots were stronger than seedlings.The higher concentration,the stronger inhibitory. And we found that the morphology of root had changed,malformations or rot .Generally,the weiht of seedlings was a kind of comprehensive expression,and the effect on weiht of seedlings were inhibitory.(3) The secretion of root system of alien plant could restrain the growth of crops. Amaranthus retroflexus remarkablely restrained the weight,root and seedling of wheat and corn. Moreover, Erigeron annuus remarkablely restrained the weight,root and seedling of corn.In this paper, we found that the effect of Eleusine indica is weaker,so it indicated that the way of secretion of root system was not the main allelopathic way.(4) In the contration of experiment,the seedling of rape were very sensitive for alien plants,and the inhibitory of Amaranthus retroflexus were stronger than other two alien plants.Compare to the results of petri dish,the effect of alien plant on wheat was litter,so it showed that the allelopathic effect of three alien plant were weaker in the land of wheat under the contration of soil and environment. (5) In the role of soil,the allelopathic effect was stronger.In a word,the effect of secretion of root system of alien plant on crops were different,corn > rape >wheat .And the inhibitory of alien plant effect on root was stronger than seedling of wheat.(6)The result of risk assessment showed that Erigeron annuus,Amaranthus retroflexus and Eleusine indica all belong to highly dangerous risk pests,and Eleusine indica was stronger than Amaranthus retroflexus and Erigeron annuus.