| Cynodon dactylon is the most important perennial plant in Cynodon,which is extensively used in vegetation revetment.There is abundant native Bermudagrass germplasm in China,with great potential of utilization.After a whole investigation on ecological distribution areas and growth habits of Bermudagrass populations all around the country,fourteen typical Bermudagrass accessions were selected as experimental materials.Based on systematic studies on transverse section of leaves, structures of upper and lower epidermis and the photosynthetic characteristics of varieties grown on rural area soil and vegetation concrete,and the varieties tolerant to salt stress were selected,offering theoretical basis and practical guidance to popularization of vegetation concrete technology.The main research results are blow:(1)Microscopic analyses on upper and lower epidermis of Bermudagrass varieties showed that the structures of upper and lower epidermis were similar in general when the varieties were planted on the both habitats,and there were significant differences in length and width,and number of all epidemic cells and stomata.There were great differences in 16 microscopic characteristics,but variation coefficients were not significant.The variation coefficients of long and short cells on lower epidermis of the varieties grown under saline stress and the variation coefficients of the densities of stomata on upper epidermis of the varieties grown on rural area soil were great,while variation coefficients of width of long and short cells on upper epidermis of the species grown on rural area soil were small.The variance analyses and LSD multiple comparisons showed that there were significant differences in 16 microscopic characteristics of leaves among the varieties.The principal component analyses showed that three principal components might represent the most information which 16 microscopic characteristics contained.Among the sixteen characteristics,the width of long and short cells on upper epidermis,the width and density of stomata on upper epidermis,and the length and width of short cells on lower epidermis had great load capacity,therefore,the six microscopic characteristics were the principal factors that resulted in microscopic differences among all the varieties.In general,reduced leaf areas induced by saline stress resulted from the changes in width of long and short cells and stomata.(2)The leaves of all the varieties in both habitats were composed by epidermis,diachyma and leaf veins.Variance analyses showed that leaves of varieties had remarkable differences in the thickness of leaves and upper and lower epidermis and the diameters of the first rosette structure in a side of primary vein in both habitats,and multiple comparisons showed that there were significant differences in the three parameters.The effects of vegetation concrete on anatomical structures of leaves were greater than rural area soil.Compared with control,the thickness of leaves and upper and lower epidermis became greater when the grass varieties suffered from saline stress,while the diameters of the first rosette structures in one side of primary vein became smaller.In general,the variation coefficients of thickness of upper and lower epidermis became greater under saline stress.(3)The analyses of leaf epidermis,using scanning electron microscopy,showed that there were five types of structural cells on the lower epidermis of the leaves of the varieties,i.e.,long and short cells, stomatal apparatuses,mastoids,and bristles.The varieties used in the experiments showed morphological responses to saline stress,and mastoids on upper and low epidermis increased,compared with control,and on the epidermis of some varieties,such as Sahara,Hawk,and wild type,the mastoids around stomata distributed regularly,resulting in stomatal apparatuses below the cells around them.The density of mastoids around stomatal apparatuses was higher than other parts,thus stomatal resistance increased,transpiration rated might increase,and water usage efficiency might increase.Therefore,the characteristics make the varieties to be adapted to the saline stress.Compared with control,increased stomatal density on upper and lower epidermis occurred on Kashi Bamudagrass,Sahara,Heaven,and Haw.According to the stomatal characteristics of the varieties grown on vegetation concrete,high stomatal density occurred on Kashi Bamudagrass and Sahara.In general,among varieties used in this present study,Sahara,Hawk,and Kashi Bamudagrass showed better adaptation to vegetation concrete.(4)There were not significant differences in Pn,Tr,WUE,and Gs among most varieties,but there were significant differences in daily response curves of Pn,Tr,and Gs.The differences are below:â‘ the daily response curve of Pn of varieties grown on rural area soil reached the peak earlier about 1 h than those grown on vegetation concrete.â‘¡the daily response curve of Tr of the varieties grown on vegetation concrete reached the peak earlier about 1 h than those grown on rural area soil.â‘¢the daily response curve of Gs of the varieties grown on vegetation concrete reached the peak earlier about 1 h than those grown on rural area soil.The analyses on photosynthetic characteristics of all the varieties suggested that the varieties grown on rural area soil(including 040459/680,Nanjing Bermudagrass, Sahara,Heaven,Hawk,040459,and the wild type showed better properties of Pn,Tr,WUE,and Gs,and that the varieties grown on vegetation concrete(including Hulled,Xinnong No.1,040459/680,Jackpot, Nanjing Bermudagrass,Heaven,and Hawk)showed better properties on the photosynthetic parameters. Cluster analyses and general index ordering showed that 040459/680,Nanjing Bermudagrass,Heaven, and Hawk had strong adaptation and resistance to Vegetation revetment.(5)According to the anatomic structural properties of leaves and photosynthetic parameters shown by all the varieties grown on the both habitats,Hawk,040459/680,Heaven,Nanjing should be used on vegetation concrete.
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