Study On Photosynthetic And Stoichiometric Characteristics Of Reaumuria Soongorica-salsola Passerina Mixed Under Different Precipitation Conditions

In recent years,the response of plant physiological characteristics to interspecific and environmental gradients has been a focus of research.Previous studies mainly focused on herbaceous plants,and most of them were controlled experiments.However,there were relatively few studies on the response of physiological characteristics of rare woody C₃ and C₄ plants to interspecific relations and environmental stress.The C₃ and C₄ hybrid communities in desert areas are precious hybrid growth types.The study on the photosynthetic and stoichiometric characteristics of C₃ and C₄ plants in different environmental gradientations was of great significance for revealing the photosynthetic physiological changes of desert plants adapted to the environment and the interspecific interactions.In this paper,C₃plant Reaumuria soongarica and C₄ plant Salsola passerina were taken as materials.Along the natural precipitation gradient,photosynthetic,fluorescence parameters and stoichiometric indexes of single and mixed R.soongarica and S.passerina under different habitat conditions were measured,and the response rules of photosynthetic characteristics and stoichiometric characteristics to interspecific relations and environmental stress were analyzed.The main conclusions were as followed:1?Kinds of desert plant photosynthetic characteristics because of the growth way,mixed R.soongarica net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs?higher than that of single,and on the contrary with S.passerina.The daily mean values of Pn,Tr and Gs of R.soongarica were higher than those of S.passerina,but their daily mean values of WUE were lower than those of S.passerina.With the decrease of precipitation under drought stress,Pn,Tr and Gs of monophytic or mixed R.soongarica and S.passerina all decreased gradually,but their WUE first decreased and then increased gradually,indicating that the use of light energy of the two desert plants decreased as a whole with the increase of precipitation under drought stress.2?Under the same habitat condition,when R.soongarica and S.passerina were mixed,the Fv/Fm,Yield and qP of the mixed R.soongarica were all higher than that of the single R.soongarica,while the opposite of the S.passerina.The daily mean values of Fv/Fm,Yield and qP were 14.84%,12.23%and 2.98%higher than those of S.passerina.Compared with S.passerina,qN of single R.soongarica was 16.30%higher on average,while that of mixed R.soongarica was 4.01%lower.With the decrease of precipitation,the Fv/Fm,Yield and qP of the two desert plants decreased,and the decrease of R.soongarica was obvious,indicating that R.soongarica is more sensitive to environmental stress.3?With the decrease of precipitation,the content of N and P in the leaves of the two plants decreased significantly,while the content of C increased significantly.The C content of R.soongarica increased by 7.73%on average,the N content decreased by6.20%on average,and the P content decreased by 10.61%on average.The content of N and P decreased by 5.93%and 14.03%respectively.The contents of C,N and P in rhizomes and leaves of R.soongarica and S.passerina were significantly affected by different degrees of drought stress.After the mixed of R.soongarica and S.passerina,the content of C in different organs was higher than that in single plant.The rhizome and leaf of R.soongarica increased by 5.53%,4.87%and 15.92%.The rhizomes and leaves of R.soongarica were increased by 7.96%,6.48%and 8.01%.N content in root and leaf of mixed R.soongarica was higher than that in single sand,which increased by 6.46%and 11.35%respectively.There were differences in S.passerina,root increased by 7.04%,while leaf decreased.