Physiological And Ecological Mechanism Of Indigenous Plant Suaeda Salsa Under Heavy Metal Stress In Jinchuan Mining Area

In this study,the autochthonous plant Suaeda salsa in Jinchang mining area was taken as the research object,and the soils around the mining area were selected as the experimental soil.There are five types of soil: Farmland soil,Primary soil,Primary soil + Slag + Attapulgite(the mass ratio,1:1:1),Primary soil + Tailings + Attapulgite(the mass ratio,1:1:1)and Primary soil + Tailings(the mass ratio,1:1).The physiological,photosynthetic and hydraulic indexes of Suaeda salsa in different growing periods and different soils were measured.The physiological and ecological mechanism of Suaeda salsa under heavy metal stress was studied in order to improve the theoretical basis for phytoremediation in mining area.The main conclusions of the study are as follows: 1.There were significant differences in physiological responses of Suaeda salsa to heavy metal stress in different growth periods.With the duration of heavy metal stress,the higher the tolerance of Suaeda salsa to heavy metals,the more similar the change trend of physiological indexes of Suaeda salsa.There was a significant correlation between the index of membrane system and the index of antioxidants,which indicated that the change of membrane system was closely related to the content of ROS in plants.Pb and Zn have great influence on the index of Suaeda salsa membrane system.CEC and Ni had great influence on the antioxidants of Suaeda salsa.Pb,Zn and PN had great effects on the soluble protein content of Suaeda salsa,while Cr and Ni had great effects on the free proline content of Suaeda salsa.2.The edaphic factors affecting the physiological indexes of Suaeda salsa were different in different growth stages.During the whole growth cycle,pH,Ni and Cr were the main edaphic factors affecting the changes of physiological indexes of Suaeda salsa.At the seedling stage,pH was the main edaphic factors affecting the changes of physiological indexes of Suaeda salsa.During the growing stage,Cu,Cr,Ni,Pb,Zn and PN were the main edaphic factors affecting the changes of physiological indexes of Suaeda salsa.At the mature stage,Cu,pH,Cr,Ni,Pb,Zn and PN were the main edaphic factors affecting the changes of physiological indexes of Suaeda salsa.3.The photosynthetic response of Suaeda salsa to heavy metal stress was different in different growth stages,and the change trend of photosynthetic index of Suaeda salsa was more similar with the duration of stress.During the whole growth cycle,the contents of soil Cr and Ni had great influence on the Gs of Suaeda salsa.At the seedling stage,the contents of soil Cr,Cu and Ni were the edaphic factors affecting the Pn value of Suaeda salsa;pH was the edaphic factor affecting the Gs value of Suaeda salsa;pH and CEC were the edaphic factors affecting the chlorophyll b content of Suaeda salsa.At the growing stage,the content of soil Pb,Zn and PN were the edaphic factors affecting the Pn of Suaeda salsa;the content of soil Cr was the edaphic factor affecting the Gs value of Suaeda salsa;the content of Cu and CEC were the edaphic factors affecting the Ci of Suaeda salsa;and CEC was the edaphic factor affecting the content of chlorophyll a and chlorophyll a+b.At the mature stage,the content of soil Pb,Zn and Ni were the edaphic factors affecting the Pn of Suaeda salsa;the contents of Cr and Cu were the edaphic factors affecting the Gs of Suaeda salsa;CEC and Ni was the edaphic factor affecting the chlorophyll content of Suaeda salsa.4.The edaphic factors affecting the changes of photosynthetic indexes of Suaeda salsa in different growth stages were different.During the whole growth cycle,CEC,pH,Ni and Cr were the main edaphic factors affecting the change of photosynthetic indexes of Suaeda salsa.At seedling stage,pH,Ni,Cr and CEC were the main edaphic factors affecting the changes of photosynthetic indexes of Suaeda salsa.At the growing stage,Ni,Cr,pH and CEC were the main edaphic factors affecting the changes of photosynthetic indexes in Suaeda salsa.At the mature stage,pH,Cr and Ni were the main edaphic factors affecting the change of photosynthetic indexes of Suaeda salsa.On the whole,pH,Cr and Ni were the main edaphic factors affecting the change of photosynthetic indexes of Suaeda salsa.5.Under heavy metal stress,the hydraulic conductivity and leaf hydraulic conductivity of Suaeda salsa increased,while the leaf specific conductivity increased at first and then decreased.There were significant differences in hydraulic indexes of Suaeda salsa in different growth periods.The contents of Cr and Ni in soil were the main edaphic factors affecting the leaf hydraulic conductivity of Suaeda salsa.In the two stages of growth and maturity,Cu,Ni and Cr were the main edaphic factors affecting the change of hydraulic indexes of Suaeda salsa.6.The growth period of Suaeda salsa is the most important factor affecting the physiological,photosynthetic and hydraulic changes of Suaeda salsa.In the same growth period,the physical and chemical properties of soil are the main factors affecting the physiological,photosynthetic and hydraulic changes of Suaeda salsa.Changing soil pH is a field-operable measure to improve the physiological and photosynthetic indexes of Suaeda salsa.