Studies Of Leaf Drought And Anatomy Character Of Growing In The Loess Plateau

leaf anatomical traits related to drought tolerance are investigated to for 11 local tree species growing in Loess plateau. These traits include characteristics of epidermis, stomata, palisade tissue, sponge tissue, vascular bundle sheath, etc. This study is support by a special grant for"vegetation establishment and fast forestation in Hilly and Gully Loess plateau"from the Chinese Academy of Sciences (KZCX1206203).The main findings of this study are as follows:1. The descending rank order for thickness of the whole leaf, stratum corneum and waxy layer is : the order of five Arbors is : Quercus liaotungensis; Acer stenolobum; Populu davidiana; Koelreuteria paniculata;Robinia pseudoacacia; and six sbrubs is : Caragana microphylla, Rosa xanthina, Xanthoceras sorbifolia, Ostyopsis davidiana, Syringa pubescens, Forsythia suspensa;2. There are dense hair structures in leaves of K. paniculata,especially along the major veins. There are least epidermic hairs in A. stenolobum and P. davidiana. Q. liaotungensis and R. pseudoacacia have medium amount of hair. In shrubs, the descending rank order for the density of hair are X. sorbifolia, O. davidiana, R. xanthina, F. suspensa, S. pubescens and C. microphylla。3. The arbors descending rank order for stomata density in leaves is: K. paniculata, Q. liaotungensis, R. pseudoacacia, A. stenolobum and P. davidiana ,The stomata of Populu davidiana are oval, big, and deep caved,and next one is R. pseudoacacia; The shrubs descending rank order for stomata density in leaves is O. davidiana, X. sorbifolia, F.suspensa, S. pubescens and C. microphylla。4. The Ratio of arbors descending rank order for thickness of palisade and spongy tissue is :P. davidiana, R. pseudoacacia, Q. liaotungensis, A. stenolobum and K. paniculata , There are 2 to 3 layers of palisade tissue in leaves of Q. liaotungensis and K. paniculata, and it is 2 layers in Populu davidiana, and 1 to 2 layers in R. pseudoacacia and A. stenolobum. there are palisade tissue extending to spongy tissue.In, Q. liaotungensis, R. pseudoacacia and P.davidiana; The Ratio of shrubs descending rank order for thickness of palisade and spongy tissue is :R. xanthina, C. microphylla, S. pubescens, X. sorbifolia, O. davidiana and F. suspense.5. are evident crystal structure, starch particles and mucilage cells in leaves of all arbor trees specie. In the shrubs, we only found crystals in leaves of R. xanthina, X. sorbifolia and O. davidiana ,It's around the vascular bundles, in epidermis and parenchyma cells. The crystals have star like shapes or not regular shapes.6. There are more vascular bundles,bundle sheath and strengthened sporting tissures in arbors of Q. liaotungensis A. stenolobum, P. davidiana, The bundles of R. pseudoacacia are far less developed than Q. liaotungensis; The vascular bundles of K. paniculata are evenly distributed in as in typical dicotyledonous plants. In the shrub species ,There are most dense vascular bundles in leaves of R. xanthina ,C. microphylla,O. davidiana, and the arrangement of vascular bundles,bundle sheath are well organized,It is least dense vascular bundles in S. pubescens and F. suspensa , The vascular bundles,bundle sheath of X. sorbifolia is similar with K. paniculata,7.Based on the anatomy of those leaves, the rank order for drought tolerance using a model for theses species are as follows: five Arbors: R. pseudoacacia> P. davidiana>Q. liaotungensis > K. paniculata > A. stenolobum and for six shrubs: R. xanthina > C. microphylla>X. sorbifolia>O. davidiana>F. suspensa>S. pubescens.