Mechanisms Of Tolerance Of Aseratina Adenovhora Populations With Different Invasive Histories To Biotic And Abiotic Stresses

Ageratina adenophora(Spreng.)is listed as one of the most threatening weeds in China.Since it invaded China from the China-Myanmar border in the 1840 s,it has been invaded for nearly 80 years.Studies have found that A.adenophora has strong tolerance and resistance to heavy metals and herbivores,respectively.In this paper,A.adenophora with different invasion histories in the three provinces of Yunnan,Guizhou and Sichuan were selected as the research object,and the tolerance of A.adenophora to cadmium(Cd)was preliminarily explored.Secondly,through Cd and simulated herbivory treatments,we will further reveal the trade-off mechanism between invasive plants in biotic and abiotic stresses,aiming to explore the differences in the trade-off ability of different invasive historical populations,with a view to studying the invasion mechanism and control strategies of alien plants.The important results of this article are as follows:(1)A.adenophora has strong tolerance to Cd during seed germination and seedling growth.From the germination rate,germination potential,germination index and germination rate index,it was found that Cd had significant effect on the root length of A.adenophora seeds,and there were significant differences in the germination rate,germination index and germination rate index among different invasive histories populations.Secondly,the germination ability of 1990-2019 s was significantly stronger than that of 1940-1970 s and 1970-1990 s.However,there was no significant difference in root length among different invasive histories populations.(2)Under hydroponic conditions,Cd can significantly affect the growth traits,antioxidant enzymes and biomass of A.adenophora with different invasion histories.With the increase of Cd concentration,the number of leaves,stem diameter and chlorophyll decreased significantly.The height in 1990-2019 s or 1970-1990 s was significantly higher than that in 1940-1970 s.Cd can significantly increase the activities of antioxidant enzymes.For catalase(CAT)and polyphenol oxidase(PPO),low concentration of Cd can promote,high concentration of Cd can inhibit,while peroxidase(POD)is on the contrary.Cd can significantly inhibit the accumulation of biomass,and the inhibition intensity gradually increases with the increase of Cd concentration.There was no significant difference in biomass among different invasion histories.(3)Cd and simulated herbivory can significantly affect plant growth traits and biomass.Cd had significant effects on height,stem diameter and leaf number.Height,chlorophyll and stem diameter were affected by different invasion history and simulated herbivory interaction.The biomass of A.adenophora with different invasion history was significantly affected by different simulated herbivory.The simulated herbivory rate of50%(D2)was more likely to affect the plant biomass,and the Cd could increase the stem diameter of A.adenophora.Under 50% simulated herbivory,the reduction of biomass and growth traits in 1990-2019 s was significantly less than that in 1940-1970 s and 1970-1990 s,and the tolerance in 1940-1970 s and 1970-1990 s was greater than that in 1990-2019 s.The results showed that the tolerance of Cd was compared by adding exogenous heavy metals to compare the tolerance of different populations of A.adenophora in different invasive histories,and the trade-off mechanism of different populations of A.adenophora was compared by exogenous heavy metals and simulated herbivory.The results showed that Cd had significant difference on the effect of Cd on A.adenophora,and the tolerance of Cd was better in the seed germination.The resource balance between heavy metals and simulated herbivory was also found,and the invasive history of A.adenophora was better under simulated herbivory.This indicates that it is necessary to evaluate the invasion history when studying the invasion mechanism and control strategy of invasive plants.