Study On The Response Of The Growth And Physiological Characteristics Of The Dominant Species In Wetland To Habitat Changes

Under the current background of global climate change,exploring the response of dominant plants in cold region wetland to different habitats is helpful to better protect plant germplasm resources and has important significance to the study of cold region wetland ecosystem under the changing environment.In this research,Deyeuxia angustifolia,a dominant species of wetland in Sanjiang Plain,was used as the experimental material to observe the response of its photosynthetic mechanism to different habitats by using chlorophyll fluorescence dynamics technology,in the hope of exploring the impact of different habitats on the physiological and ecological functions of wetland dominant species.The observation results show that:1.The dominant wetland plant Deyeuxia angustifolia shows strong adaptability to different water contents in the habitat.At the same time,the increase of water content in the habitat will reduce the PS?photochemical function of Deyeuxia angustifolia leaves and increase the ineffective heat energy dissipated by Deyeuxia angustifolia.The result of the experiment showed that the maximum photochemical efficiency and photosynthetic performance index of swamp Deyeuxia angustifolia were weaker than those of swamp meadow Deyeuxia angustifolia and meadow Deyeuxia angustifolia;Analyze it further,after standardizing the OJIP curve of Deyeuxia angustifolia leaves,it was found that the electron transfer rate of PS? reaction center and the stability of inner capsule membrane in swamp Deyeuxia angustifolia located in the habitat with higher water content were weaker than those in swamp meadow Deyeuxia angustifolia and meadow Deyeuxia angustifolia;with the decrease of water content in the habitat,the proportion of ineffective heat energy dissipated by the leaves of Deyeuxia angustifolia is also reduced,that is,the absorbed light energy is more used in the photochemical reaction center for photosynthesis;However,there was no significant difference between the observation results of swamp meadow Deyeuxia angustifolia and meadow Deyeuxia angustifolia,which indicating that the PS?photochemical function of Deyeuxia angustifolia has stronger adaptability to different water contents in habitat.2.Although the increase of CO₂ concentration decreased the stomatal conductance and transpiration rate of Deyeuxia angustifolia leaves,it improved the water use efficiency.Under the treatment of 700?mol·mol-1CO₂ concentration,it was found that the net photosynthetic rate(P_n)of Deyeuxia angustifolia increased first and then decreased with the extension of action time,the stomatal conductance(g_s)and transpiration rate(T_r)showed a downward trend,while the water use efficiency(WUE)increased.At the same time,it was found that the increase of CO₂ concentration increased the chlorophyll content per unit area,and the distribution position of chloroplast also expanded when observed the leaf morphology and structure of Deyeuxia angustifolia.3.The increase of CO₂ concentration will lead to the improvement of PS? function of Deyeuxia angustifolia seedlings under drought stress,so as to improve its drought resistance.Under drought stress,the increase of CO₂ concentration not only increased the PS? photochemical activity and WUE of the leaves of Deyeuxia angustifolia seedlings,but also improved the electron transfer capacity in the photochemical reaction center,and reduced the proportion of energy used for dissipation.At habitat in the moisture content is higher,by reducing the wetland photochemical rate of dominant species Deyeuxia angustifolia and light reaction center of electron transfer ability to reduce Deyeuxia angustifolia PS? photochemical activity,and elevated CO₂concentration in the habitat although chapter will reduce lobular seedling leaf stomatal conductance,but it can increase its net photosynthetic rate and water use efficiency.Under non-drought conditions,increased CO₂concentration had little effect on PS? photochemical activity and electron transport in leaves of Deyeuxia angustifolia seedlings.Under drought conditions,the increase of CO₂ concentration could not only adapt to drought stress by increasing water use efficiency of Deyeuxia angustifolia seedlings leaves,but also reduce the inhibition of photochemical activity of PS? leaves under drought stress,promote photosynthetic electron transfer of PS?,and alleviate the damage degree of OEC in PS?.To some extent,the stability of thylakoid membrane can be improved,and the photochemical activity of PS? in leaves can be relatively improved,and finally the photosynthetic function of phyllobules can be improved.