Invasive Biological Characteristics And Rhizosphere Microbial Community Of Tagetes Minuta L.

Tagetes minuta L.is a new invasive weed in China in recent years.It has caused local damage in several provinces,including Beijing,Hebei,Shandong,Shanxi,Tibet and so on.So it is an urgent problem to study its biological characteristics and invasion mechanism in China.In this paper,with T.minuta as the research object,the germination characteristics and the influence of intraspecific competition on the reproduction of T.minuta were clarified.And the influence of its invasion on soil bacterial community was explored.In addition,we screened and the herbicides with high efficiency for prevention and control of T.minuta.The results showed that:1.The seeds of T.minuta are most suitable for germination in the dark,25??30?and 25%humidity environment,the GP,GE and GI are the highest.Light inhibited the germination of seeds,and variable temperature promoted the germination.Intraspecific competition inhibited the growth and reproduction of T.minuta,and the higher the density,the stronger the inhibition.The average biomass per plant,average seed yield per plant and density showed a power function of allometric correlation,and the seed yield unit area and density showed a logarithmic function.2.Compared with marigold(Tagetes erecta L.),T.minuta significantly increased the diversity of soil bacterial community.TK of the soil is an important factor to affect the bacterial community structure in the rhizosphere of T.minuta,Actinobacteria,Nitrospirae,Proteobacteria and other phyla in rhizosphere soil are significantly positively correlated with TK(P<0.05).Lefse multi-level discriminant analysis showed that the 10 OTU groups of 8 families were significantly enriched in the rhizosphere soil of T.minuta,including Polyangiaceae,Nannocystaceae and Nostocaceae,which may play an important role in the invasion process of T.minuta.3.Glyphosate isopropylamine salt AS(900 g a.i.·hm^-2),Picloram AS(1050 g a.i.·hm^-2)and Bromoxyniloctanoate EC(70 g a.i.·hm^-2)had better control effect on T.minuta.The control effect of fresh weight was 91.08%,90.92%and 93.30%,the control effect of plant was 97.25%,91.33%and 96.06%respectively.The three herbicides could be used for emergency control of T.minuta in non-cultivated land,forest,orchard and farmland.In short,T.minuta is prone to damage in the habitat disturbed by tillage,and the damage is the highest at the density of 50 plants per unit area.Moreover,T.minuta changed the structure of soil microbial community,improved the utilization of potassium in soil,and enhanced the competitiveness.Combined with the local environment,we can control it by spraying herbicides,such as Glyphosate isopropylamine salt,Picloram and Bromoxyniloctanoate.The above contents provided theoretical basis and technical support for early warning,revealing its invasion mechanism and scientific control it.