The Study On The Flooding Resistances Of Some Fine Landscape Trees In Urban Forests

The two-year seedlings of Taxodium distichum, Cinnamomum camphora, C. platyphyllum, Quercus nuttallii and Q. shumardii under the water treatments (CK: normal; W1: shallow flooding stress; W2: deep flooding stress) were studied. And their growth indexes, physiological and biochemical characteristics were analysed systematically to serve the urban forests. The main conclusions were drawn as follows:1) Shallow flooding stress accelerated the growth in height and biomass of Taxodium distichum and Quercus nuttallii, especially for Taxodium distichum. The effects of deep flooding stress on Taxodium distichum and Quercus nuttallii were obscure, but deep flooding stress restrained Cinnamomum camphora,C. platyphyllum and Quercus shumardii, especially for Cinnamomum platyphyllum and Quercus shumardiii. Then water was drained out after finishing flooding. Two months later, the five species under shallow flooding stress were all survival. Under deep flooding stress, Taxodium distichum and Quercus nuttallii were all survival and the survival rates of Cinnamomum camphora,C. platyphyllum and Quercus shumardii were only 80%,60% and 30%.2) Under flooding stress, Pn, Cond and Tr declined but Ci increased. The extents of all indexes under deep flooding stress were larger than that under shallow flooding stress. The flooding resistance is Taxodium distichum >Quercus nuttallii >Cinnamomum camphora >C. platyphyllum >Quercus shumardii.3) Under shallow flooding stress, the selective permeability of cell membrane changed faintly, while the others distinctly increased. Under deep flooding stress, the tendency of Taxodium distichum was slowly up then down, while the others always increased, especially for Quercus shumardii.Under flooding stress, the variation of free prolin content in the Taxodium distichum was obscure while the others decreased. The soluble sugar contents in five species were up firstly and later down. MDA content in test trees increased. And the tendency of all indexes under deep flooding stress was more obvious.SOD activity under shallow flooding stress increased while it was firstly up and then down under deep flooding. POD activities of Taxodium distichum and Quercus nuttallii were always up, while the others were up firstly and down later. CAT activity increased and the extent under deep flooding stress was larger than that under shallow flooding stress. The results of POD isoenzymes showed that the damage for Quercus shumardii was the strongest under flooding stress.Flooding stress inhibited the growth of roots obviously and made the roots dark even rotted.It was clear that the root vigor declined especially for Cinnamomum platyphyllum and Quercus shumardii. ADH activities of all roots increased except Quercus shumardii.The flooding resistance is Taxodium distichum >Quercus nuttallii >Cinnamomum camphora >C. platyphyllum > Quercus shumardii.4) It was not obvious for anatomic in the Taxodium distichum under flooding stress. Under deep flooding the cell clearance became bigger and more metamorphosed. Arrangement of cells was abnormal, especially for Quercus shumardii.5) Based on the systematical and comprehensive analyses, the order of flooding resistance for five species from the strong to the weak was Taxodium distichum, Quercus nuttallii, Cinnamomum camphora, C. platyphyllum ,Quercus shumardii.