Evaluation Of Salt Tolerance Of 21 Ornamental Chrysanthemum And Photosystem Characteristics Analysis

Chrysanthemum has high ornamental effect and garden application value,and will be affected by a variety of environmental factors during the growth process,and salt is one of the important factors affecting its growth and development.In order to explore the salt tolerance of different ornamental chrysanthemum cultivars,21 ornamental chrysanthemum varieties were treated with salt stress,their growth and physiological and biochemical indexes were studied,and the salt tolerance was comprehensively evaluated by multivariate analysis.Strong salt tolerance cultivars,medium salt tolerance cultivars and salt-sensitive cultivars were selected for chlorophyll fluorescence characteristics to explore the changes of ornamental chrysanthemum photosystem and fluorescence parameters under salt stress.The main results are as follows:(1)Under the salt stress treatment of 200 m M,the salt damage status of different ornamental chrysanthemum cultivars was different,and the plants of ’Q19-1-8’’Q19-3-40’ and ’Q19-5-103’ could remain healthy on the 9th day,while the varieties ’Q19-2-71’’Q19-3-38’ and ’Q19-6-14’ showed leaf water loss and leaf tip yellowing on the 4th day,and some stems and leaves withered on the 9th day.(2)Under the treatment of 200 m M Na Cl,the plant height,stem thickness,Pn,Tr,Gs,WUE,AMC,chlorophyll content and relative water content of A.ornamental chrysanthemum decreased.POD activity,proline content,MDA content and relative conductivity increased.Ci,Ls,SOD activity and soluble protein content showed certain differences in different varieties.Among them,cultivars ’Q19-1-8’ and cultivars ’Q19-3-40’ decreased less in stem thickness,water efficiency and chlorophyll content,while soluble protein content and proline content increased significantly.The Pn,relative water content and chlorophyll content of cultivars ’Q19-2-71’ and cultivars ’Q19-6-14’decreased significantly,while the relative conductivity and MDA contents increased significantly.(3)Based on the changes of 22 growth and physiological and biochemical indexes,and using cluster analysis,the 21 ornamental chrysanthemum varieties were divided into 5 categories: varieties with strong salt tolerance,including ’Q19-3-40’ and’Q19-1-8’;varieties with strong salt tolerance: ’Q19-5-103’ ’Q19-3-4’ ’Q19-5-43’,’Q19-6-26’ and ’Q19-1-50’;medium salt tolerance varieties: ’Q19-5-14’ ’Q19-5-68’,’Q19-1-37’ ’Q19-6-18’,’Q19-4-5’ and ’Q19-2-76’;salt resistant varieties: ’Q19-2-16’,’Q19-5-27’,’Q19-3-38’ ’Q19-5-75’ ’Q19-2-78’ and ’Q19-4-20’;salt-sensitive varieties are ’Q19-2-71’ and ’Q19-6-14’.(4)Under salt stress,there were no significant changes in Fm,Fv/Fm and Fv/Fo in the variety ’Q19-3-40’PSII,indicating that salt stress had little effect on the activity of the PSII reaction center of the cultivar,while ψRo,φRo and δRo decreased,and the coordination(REo/RC)and patency(REo/CSo)between PSI and PSII decreased,indicating that the PSI receptor side of this variety had a hindered electron transport PSII and PSII was insensitive to salt stress.The Fm,Fv/Fm and Fv/Fo of the cultivar’Q19-2-71’ decreased significantly,indicating that salt stress reduced the photochemical activity of ’Q19-2-71’ PSII,while the coordination between PSI and PSII(REo/RC)and δRo showed a trend of first decreasing and then rising during salt stress,ψRo and φRo showed a slight downward trend,and continuous salt stress had a certain effect on the PSI and PSII donor sides of salt-sensitive varieties ’Q19-2-71’.This study established a comprehensive evaluation system for salt tolerance of ornamental chrysanthemums.Based on salt tolerance,21 ornamental chrysanthemum varieties were divided into 5 categories using cluster analysis,with varieties’ Q19-3-4 ’and’ Q19-1-8 ’having the strongest salt tolerance;Under salt stress,both the PSII and PSI of salt sensitive variety ’Q19-2-71’ were damaged to varying degrees.The PSII of the strong salt tolerant variety ’Q19-3-40’ was not significantly affected.The results of this experiment provide practical and theoretical basis for the breeding,production and cultivation of salt tolerant varieties of ornamental chrysanthemums,as well as for the promotion and application of gardens.