Research On Ecological Control Of Invasive Plant Flaveria Bidentis

Flaveria bidentis is a compositae annual herb, which native is belong to South America, is an invasive weed in China.It was first found in Tianjin and Hebei Hengshui City in 2001 in China, this plant has been appeared in Tianjin, Hebei, Henan, Shandong, its growth and spread is rapidly and its biological invasion is very seriously. In order to suppress invasion harm of Flaveria bidentis.According to plant species competition principle,this study selects a variety of grasses which have fast growth and high economic value to suppress Flaveria bidentis's spread ,to research competitive inhibitory effect, the effect on invasion of soil nutrients and soil activity and to explore its physical and chemical mechanisms of biological regulation. The main results are as follows:1. In present study, a greenhouse competition experiment was conducted with three pasture species, Lolium perenne, Medicago sativa and Sorghum hybrid sudanense as the material of invasive plant Flaveria bidentis, given different densities and proportions combination, to investigate their competitive behavior.(1) Comparison of growth inhibition shows that on Flaveria bidentis height, biomass, number of branches of the control effect Sorghum hybrid sudanense was significant or highly significant in the high density (8 plants / pot), a low ratio (1:3) under Flaveria bidentis highly significant inhibition, in which plant height, biomass and branch number inhibition rates were 60.00%, 91.40% and 64.71%, while the the control of Lolium perenne and Medicago sativa is less effective,it is not significant in a variety of treatments inhibitory effect on Flaveria bidentis.(2) Relative yield comparisons shows that Sorghum hybrid sudanense inhibitory effect was significantly higher than the other two pasture species, in all growth stages, in addition to high density Sorghum hybrid sudanense replacing portfolio, other combinations the relative yield values of Flaveria bidentis were significantly lower than 1.0, significantly inhibited the growth by which control effect than other seedling growth stage; Lolium perenne , Medicago sativa and Flaveria bidentis's effect of competitive alternatives have no significant.(3) Physiological mechanism showed that, SOD, POD enzyme activity, soluble protein content of Flaveria bidentis seedling leaf among treatments in the alternative combinations was not significant.Study concluded that, 1:3 ratio of plants in Sorghum hybrid sudanense and Flaveria bidentis under the control effect is remarkable, Sorghum hybrid sudanense can be used as biological bidentis alternative materials.2. In field test, the effect of five kinds of herb biological alternative Flaveria bidentis to soil fertility and soil enzyme activity results show that:(1) Community Flaveria bidentis rhizosphere soil NH4 +-N, NO3 - N levels were significantly lower than the top of Medicago sativa and Flaveria bidentis combined community, and its phosphorus content was significantly lower than Sorghum hybrid sudanense and Flaveria bidentis community.(2) Three kinds of enzyme(Urease, phosphatase, invertase) activities of Medicago sativa and Flaveria bidentis combination were significantly higher than Flaveria bidentis community.(3) Enzyme activity and soil fertility correlations between different results showed that , urease content as to Sorghum hybrid sudanense and Flaveria bidentis combination, Medicago sativa and Flaveria bidentis combined community, was significantly positively related to nitrate nitrogen, ammonium nitrogen content. Phosphatases in Medicago sativa and Flaveria bidentis combination of community and available phosphorus were positively correlated, meanwhile invertase in Sorghum hybrid sudanense and Flaveria bidentis combination show significant negative correlation. It can be inferred that Sorghum hybrid sudanense and Medicago sativa own stronger activity of nitrogen compounds in soil than Flaveria bidentis, and with the help of interspecific competition, they can inhibit Flaveria bidentis from activating of soil available phosphorus, in order to achieve competitive inhibition.The study concluded that Sorghum hybrid sudanense and Medicago sativa can recommend as the field of biological substitutes for Flaveria bidentis.