Growth And Reproduction Function Traits Of Invasive Tithonia Diversifolia

The functional traits of plants have become a reliable way to interpret some important ecological problems in the scale of population,community and ecosystem.The invasive plants can quickly adapt to the local habitat and gradually spread,with obvious competitive advantage.And in the course of the invasion of different regions,the functional traits of growth,physiology,and reproduction are different.Therefore,attention to the relationship between environmental factors and the phenotypic characteristics of invasive plants can provide a basis for explaining their invasiveness and predicting the spread tendency.This research takes the case of Tithonia diversifolia,a typical invasive plant in Yunnan province,to study the difference of main growth and reproductive functional traits under different environmental conditions.From habitat type,elevation,latitude and soil fertility this four factors analysis the effects of environmental factors on traits,and explore its adaptation characteristics,aiming to reveal the ecological basis of its successful settlement and diffusion to a certain extent.The results showed:(1)The growth traits(plant height,leaf area,leaf thickness,specific leaf area,dry matter content of stem and leaf)and reproductive traits(seed yield,1000-grain weight,seed abortion rate,seed vigor)of T.diversifolia in different regions have significant differences,while the number of sprouts was not significant,which indicating that its growth and reproductive traits on the environmental factors are more sensitive,but the ability to asexual reproduction is relatively stable.(2)The contents of N,P and K in the leaves along altitudinal gradients were significantly different,but the average mass fraction of the three elements was not significantly different.On the one hand that its growth is limited by resources,on the other hand reflects its similarity to soil nutrient use efficiency.(3)In the growth traits of T.diversifolia,there was a significant positive correlation between leaf area and leaf N content and leaf K content,and a negative correlation between leaf thickness and leaf N content and leaf K content,between leaf area,leaf P content and other traits there was no correlation;in the reproductive traits,seed yield while the 1000-grain weight,seed abortion rate,seed vigor have no obvious correlation,seed abortive rate and seed vigor also does not have obvious correlation.(4)The leaf thickness,the dry matter content of leaves were positively correlated with the altitude and elevation,while the leaf area has a negative correlation with altitude and elevation.The correlation between reproductive traits and altitudinal gradient was not significant.(5)The plant height and leaf N content of T.diversifolia were positively correlated with the hydrolytic N in soil,There was no significant correlation between leaf P content and soil available P,and leaf K content had no significant correlation with soil available K;while seed yield,1000-grain weight and germination number were not significantly correlated with soil N,P and K contents.(6)The plant height,basal diameter,leaf thickness and specific leaf area were significant differences in different habitat types(highway,national highway,farmland and wasteland);But there was no significant difference in leaf area and leaf N,P and K contents.The difference of reproductive traits was mainly due to the low abortion rate and high germination rate in the wasteland habitat.While in the high-speed road system,there were high seed abortion rate and low germination rate;national highway farmland habitats have no significant difference.In general,most of the functional traits of T.diversifolia in different regions of Yunnan province were in various types,and some can keep stable status,indicating a comprehensive response to impact on environmental heterogeneity and disturbance,reflecting its ability to quickly adapt to invasive habitats and make full use of resources.This features is significantly helpful for its settlement and diffusion.Because its requirement forhabitat quality is not high and the propagules are easy to spread by man,we should pay more attention on the diffusion paths and habitat spaces created in the process of road construction and rural urbanization.