Responses Of Different Clones Of Hybrid Tulip Tree To Flooding Stress

The hybrid tulip tree (Liriodendron chinense×L. tulipifera) is a kind of tree which is badly in need of cultivation for ornamental and industrial material in recent years in China.With the aim of laying a solid foundation for breeding flooding-resistance hybrid tulip tree and offering scientific basis for its promotion and application, different clones of hybrid tulip tree were adopted to study the change of appearance, the physiological biochemistry characteristics which related with environment stress, the endogenous hormones as well as the photosynthesis characteristics under flooding stress. The main results were shown as follows:1. All clones were injured to various degrees under flooding stress. The leaves became yellow and the chlorophyll content reduced. The roots were rotten and the roots activities dropped. According to the flooding index, 48, 39, 49and 13 clones had resistance to flooding stress. However, 23, 63, 40 and 75 clones were sensitive to flooding stress.2. During the process of the flooding stress, membrane penetrability and MDA content in leaves of all clones increased, the increase was less in flooding-resistance clones. The change of SOD and POD activities had differences in time and range; flooding-resistance clones could keep high enzyme activities. ADH and PAL activities enhanced under flooding stress, flooding-resistance clones had higher enzyme activities and could hold long time. At the same time, the soluble protein content in leaves changed and free proline content rose, more free proline were tested in flooding-sensitive clones.3. Eleven physiological and biochemical indexes which related with environment stress were treated by using principal component analysis and subordinative function to make comprehensive evaluation to different clones, the sequence of resisting to flooding stress was ranked as follows , 39 >48>13>49>63>23>75>40.4. Flooding-resistance clones (39, 48) and flooding-sensitive clones (40, 75) were selected to study the change of endogenous hormones under flooding stress. ABA content showed a trend of rise-fall-rise, the change was slower in flooding-resistance clones. However, IAA content...