| Due to the increase of soil salinization, how to analysis the formation of the different salinized soil and enhance the plant's tolerance to salt are gradually focused on. Therefore, the salinized soil of Tianjin seashore area is studied with the changing of season and space to improving the alkali-soil. We also study the plant's salt-tolerance mechanism and screening methods in order to select some salt-tolerance plant and change the salinity region.Through statistical analysis of the soil major ions, electrical conductivity and temporal and spatial distribution characteristics of the different salinity regions in Tianjin seashore area, the results show that the main soil irons content Na+, Cl-, SO42- in the research areas; the high concentration of Na+, Cl-, SO42-, Ca2+, K+ are gathering in surface layer and have a highly significant correlation with each other and total salt in the high salinity region(>0.930), also have a higher coefficient of variation in the winter; the content of Na+, Cl-, SO42-, Ca2+ are lower in the surface layer between the low and medium salinity region and have not significant difference in the seasons. Effected by the eluviation, the four ions are gathering in the 40 cm soil layer, and SO42-, K+, Ca2+, HCO3- have a higher coefficient of variation in the autumn. Compared with the high salinity region, only Na+, Cl- and the total salt have a highly significant correlation in the low salinity region.By studying one year-old seedlings of Rosa woodsii Lindl., Acer negundo Linn. and Triploid Platycladus orientalis, we determined their relative growth, total content of chlorophyll, leaf electric relative conductivity, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate under different salt stress (CK, 1‰, 2‰, 4‰, 6‰). The results show that with the salt stress concentration increasing, the relative growth, total content of chlorophyll, net photosynthetic rate, stomatal conductance and transpiration rate in these seedlings decreased, but the leaf electric relative conductivity increased and intercellular CO2 concentration have no significant change except that Triploid Platycladus orientalis decreased to some extent in the low-salt stress. Na+, K+ and Ca2+ content also have the different changes in all three seedlings. It is concluded that K+ and Ca2+ are mainly osmotic adjustment substance in Rosa woodsii Lindl.; K+ is mainly osmotic adjustment substance in Acer negundo Linn.; Na+ is accumulated on the underground part, while K+ and Ca2+ keep stable in above-ground part in order to maintain their growth under salt stress.In order to extend breeding, with seeds of Acer campestre, Acer ginnala, Acer negundo, Fraxinus Americana, Fraxinus pennsylvanica, Gleditsia triacanthos, Rhus glabra and Rhus trilobata as tested materials, we determined their net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate under different salt stress (CK, 2‰, 4‰, 6‰). The results show that the relative seedling rate and height of eight trees seedlings are decreased. With salt-stress with the salt stress concentration increasing, net photosynthetic rate, stomatal conductance and transpiration rate are decreased in Acer ginnala, Acer negundo, Fraxinus pennsylvanica, Gleditsia triacanthos and Rhus glabra, but intercellular CO2 concentration have no significant change in eight trees seedlings. The value of Fo,Fm,Fv,Fv/Fm and Fv/Fo are reduced in eight trees seedlings. With the different salt stress, Na+ content are gradually increased in Acer negundo, but the absorption of K+ and Ca2+ are decent. Rhus trilobata and Gleditsia triacanthos can maintain a low osmosis and cell membrane integrity by emitting of Na+. The salt tolerances of these eight trees seedlings are evaluated with membership function by detemining the ten physiological indexes. The results show that Rhus trilobata is strongest in salt-resistant, followed by Fraxinus Americana, Gleditsia triacanthos, Fraxinus pennsylvanica, Acer negundo, Acer ginnala, Acer campestre and Rhus glabra. |
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