Response Of Growth Characteristics Of Tamarix Chinensis Seedlings To Different Water And Salt Environments

In Ejina oasis,the shortage of water resources and salinization of soil caused by global change have a strong negative impact on the propagation and expansion of Populus euphratica population;on the other hand,the large-scale expansion of Tamarix chinensis,the dominant shrub species in the oasis,has also occupied the habitat of P.euphratica,resulting in the decline of survival rate of its seedlings.Therefore,it is an important theoretical and practical problem to explore the protection path of P.euphratica forest from the perspective of controlling the population spread of T.chinensis.Combined with this problem,this study used the control experiment method to explore how the growth characteristics of T.chinensis seedlings respond to different water and salt environments by setting three water and salt gradients and four time gradients,a total of 12 treatment combinations,so as to provide theoretical basis for P.euphratica forest protection and oasis ecosystem management.The results are as follows:(1)Under different water and salt treatment,the growth dynamics of plant height,base diameter,branch number,fresh weight on the ground,biomass on the ground and ratio of root to crown of T.chinensis seedlings are increasing type,the growth dynamics of leaf thickness is decreasing type,and the growth dynamics of specific leaf area is single peak type;the growth of the above ground part of T.chinensis seedlings is more favorable under the environment of low water and low salt,and the major constraint factor that have an impact on the growth of the above ground part of T.chinensis seedlings is the content of salt.(2)Under different water and salt treatment,the growth dynamics of total root length,main root length,root surface area,root volume and average root diameter of T.chinensis seedlings are increasing type,the growth dynamics of root tip number is V type(decreasing first and increasing later),the growth dynamics of average link length is single peak type,the growth dynamics of topological index is fluctuating type in low water and low salt environment,and decreasing type in high water,high salt and medium salt environment;dry type Drought stress can promote the increase of total root length,main root length,root volume,average root diameter,fresh weight and dry weight of root,and the change of topological structure to fish tail branch.High salt stress can promote the increase of average link length of T.chinensis seedlings.There was no significant difference in response of tips number and average link length to different water and salt environments.(3)Under different water and salt treatment,the dynamic changes of C element,N element,P element and N: P element of T.chinensis seedlings are fluctuating,decreasing,and increasing.The chemometric characteristics of T.chinensis seedlings are different in different water and salt environments.Generally speaking,the C content,P content and C: n are higher in middle water and salt environments,and element and N: P are higher in high water and salt environments.The chemical and quantitative characteristics of T.chinensis seedlings are decreasing C.N,P,C: N and N: P cooperate with each other and play a role in the process of growth,development and physiological metabolism.In conclusion,soil salt is the main factor limiting the aboveground growth and root expansion of T.chinensis seedlings,but it has no significant effect on the content of C,N,P and C: N,N: P of that.