| Koelreuteria bipinnata var. integrifoliola belongs to koelreuteria Sapindoideae.It is deciduous tree which has yellow flower, capsule like vesicle with a color of bronzing or nacarat when matured. It is used to be the avenue tree,garden tree and scenery tree becaused of its high ornamental value. The study took the two-years-old seedlings of Koelreuteria bipinnata var. integrifoliola as test materials. Using drought stress and the simulation of natural flooding for Koelreuteria bipinnata var. integrifoliola were treated with water stress, studying the changes of seedling growth and physiological were determinated for exploreing its drought tolerance and waterlogging ability, the results show that:(1)The drouht stress experiment was carried out under persistent drought stress which was set a time gradient of stopping water for 0d, 4d, 8d,12 d, 16 d and 20 d. The results showed that: Koelreuteria bipinnata var. integrifoliola seedlings adapt to the intensified drought stress by decreased biomass, leaf weight and increased stem, root and shoot ratio. With the prolonged drought stress and continuous declination of soil water content, the leaf’s relative water content rose first and then decreased substantially afterwards,and the relative electrical conductivity of leaf increased. Besides,the Chl, Chla and Chlb content rose first and decreased afterwards as well as the contents of the Car/Chla, Car /Chlb.In the whole process of drought stress, the soluble protein content, POD and the activity of SOD in leaves increased first and then decreased, the content of praline increased, the MDA content related with membrane lipid oxidation reaction process was increased firstly and then decreased,The content of soluble protein began to decrease when treated for 8d under drought stress,while POD and SOD activity declined, MDA which was the products of membrane lipid peroxidation began to increase.The results indicated that the drought resistance of Koelreuteria bipinnata var. integrifoliola seedling was not very good.(2)The way of double pots was taken in this flooding stress experiment,and three treatments were set which were normal watering(CK), water logging(ZK) and subsurface watering(LK) to research the influence on growth,osmotic substance content and fluorescence properties of the Koelreuteria bipinnata var. integrifoliola seedlings. The result showed that the Leaves almost fell at the 31 d under the treatment of ZK, and part of the leaves under treatment of LK turned yellow. With the extension of waterlogging time, the proline contents,soluble sugar contents, Fo value and NPQ value of ZK seedlings and LK seedlings are increase significantly. And it respectively increases by 301% and 263%, 220% and 144%, 20.61% and 8.2%, 86.84% and 8.2%. While the Fm, Fv/Fm, ETR of them drop substantially, reduce by 78.89 and 42.80%,73.63% and 45.25%, 77.71% and 53.50%. But the rangeability in LK seedlings is much smaller than in ZK seedlings. This result is consistent with the appearance of morphological changes. It shows that the effects of ZK is much larger than LK for Koelreuteria bipinnata var. integrifoliola Seedlings. A long time of waterlogging, Koelreuteria bipinnata var. integrifoliola may survive, but a long time of waterlogging, it may die. |
