Effects Of Abscisic Acid And Sodium Tungstate Dihydrate On Invasiveness Of Wedelia Trilobata And Their Regulation Mechanisms

Currently,how to effectively prevent and control invasive plants is a scientific problem that researchers pay more attention to and a difficult problem that needs to be tackled.Abscisic acid(ABA),as one of the six endogenous plant hormones,plays a very key role in the response of plants to changes in the external environment.Although the research in some model plants and crops is relatively mature,the role of abscisic acid in the process of alien plant invasion is still unclear.Therefore,our study intends to combine factors such as application methods and changes in environmental conditions(changes in light intensity,changes in competition mode),and compare the effects of abscisic acid substances-exogenous ABA and sodium tungstate dihydrate(abscisic acid synthesis inhibitor)on the phenotypic characteristics,photosynthetic characteristics,antioxidant system and endogenous hormone ratio of the compositae invasive plants--Wedelia trilobata and the native plants--Wedelia chinensis.The regulation law of the invasiveness of the alien plants W.trilobata in response to ABA and sodium tungstate dihydrate was explored,in order to provide a solid theoretical basis and data support for the hormone-level prevention and control of invasive plants.The main research results in this paper are as follows:(1)In terms of the application method of abscisic acid substances,compared with spraying,ABA or sodium tungstate dihydrate applied by irrigation have a more significant effect on the growth of W.trilobata and W.chinensis.Regardless of the application method,the effect of exogenous ABA treatment on the growth of the two plants was not significant,but high-concentration ABA treatment significantly reduced the stomatal conductance and transpiration rate of W.trilobata leaves.Different concentrations of sodium tungstate dihydrate treatment significantly inhibit the growth of two plants.With the increase of sodium tungstate dihydrate concentration,this inhibitory effect becomes more significant.It was not only reflected in the plant height,leaf,root development and other growth index,but also reflected in a significant decrease in its photosynthesis and a significant increase in antioxidant system.The effect of ABA treatment or sodium tungstate dihydrate treatment by irrigation on the chlorophyll content of the leaves of the W.trilobata and W.chinensis was opposite,which also verified that the influence mechanisms of the two plants were different.(2)In terms of different light intensity levels,whether it is exogenous ABA treatment or sodium tungstate dihydrate treatment,low light intensity conditions significantly inhibited the growth of W.trilobata and W.chinensis in varying degrees.Unlike W.chinensis,sodium tungstate dihydrate treatment significantly increased the plant height of W.trilobata,while exogenous ABA treatment significantly increased its photosynthetic rate under low light intensity.At the same time,although sodium tungstate dihydrate treatment significantly increased the antioxidant enzyme activity and Malondialdehyde content of the two plants under low light intensity conditions,the changes in the antioxidant system of the two plants under the exogenous ABA treatment were not the same.(3)From the influence of different competition modes,with the change of Wt:Wc planting ratio,the growth of W.trilobata and W.chinensis are inhibited to varying degrees.Exogenous ABA treatment may alleviate the negative effects of interspecific competition on the two plants,while sodium tungstate dihydrate treatment significantly aggravated this effects.From the competition indicators of the two plants under different competitive modes,under the sodium tungstate dihydrate treatment,there is an obvious competitive relationship between W.trilobata and W.chinensis,and the competitiveness of W.trilobata lesser than W.chinensis.With the change of Wt:Wc planting ratio,ABA and sodium tungstate dihydrate treatments changed the photosynthesis and antioxidant systems of the two plants to varying degrees.(4)In terms of the changes of the endogenous hormones ratio of the two plants,compared with controls,sodium tungstate dihydrate treatment by irrigation significantly increased the ratio of ABA/IAA and ABA/GA in the above-ground part of two plants.Exogenous ABA treatment by irrigation significantly increased the ratio of ABA/IAA and ABA/GA in the below-ground part of W.trilobata,while applying exogenous ABA treatment by spraying significantly reduced the ratio of ABA/IAA in the below-ground part of W.trilobata.And compared with W.chinensis,exogenous ABA treatment had an large impact on the endogenous hormone ratio of the W.trilobata.Exogenous ABA and sodium tungstate dihydrate treatments have no significant effect on the ratio of IAA/GA in two plant under different light intensities.Under low light intensity conditions,exogenous ABA treatment significantly increased the ratios of ABA/IAA and ABA/GA in the above-ground and below-ground of W.trilobata,while sodium tungstate dihydrate treatment could significantly increase the ratios of ABA/IAA and ABA/GA in the below-ground part of two plants.Under different planting ratios of Wt:Wc,sodium tungstate dihydrate treatment had no significant effect on the endogenous hormone ratio of the above-and below-ground of W.trilobata.Compared with single planting,as the planting ratio of Wt:Wc decreased,the above-ground ABA/GA ratio of W.chinensis decreased significantly,and the below-ground ABA/GA ratio increased significantly.Correlation analysis shows that the changes in the endogenous hormones ratio of the two plant are corresponding and closely related to the changes in plant growth index,photosynthesis,and antioxidant enzyme activities.In summary,the research results of this paper show that: the application of exogenous ABA and sodium tungstate dihydrate by irrigation had more significant effects on the growth of W.trilobata and W.chinensis,and the impact mechanisms of exogenous ABA and sodium tungstate dihydrate treatments on the two plants were different;low light intensity conditions significantly increased the inhibitory effect of sodium tungstate dihydrate on the growth of two plants;exogenous ABA and sodium tungstate dihydrate treatment could change the competitive relationship between the two plants to a certain extent;the changes in the ratio of the endogenous hormone contents of the two plants under each treatment condition were corresponding and closely related to plant growth and physiological as well as biochemical indicators.