Comparative Study On The Structure Of Jasminum Nudiflorum Lindl.in Different Ecological Environments

In this paper,using paraffin section technique,wood section technique,the plant print identification technology and optical photomicrography technique,to have the system of the structure comparison research and mathematical statistics analysis on the young stem,petioles,leaves and stem secondary xylem of Jasminum nudiflorum Lindl.which are lived in different ecological environments: shade,sun,drought and wet.To discuss the differences in structure of J.nudiflorum Lindl.under the shade stress and drought stress,aims at providing the theoretical foundation for rivalry adversity research and the fine varieties screening,at the same time,in order to improve the urban greening,increase the ecological and economic benefit of land resource utilization and to provide scientific reference for desertification prevention.The research results of shade environment showed that relative to the J.nudiflorum Lindl.in the sun and drought,the J.nudiflorum Lindl.in the shade and drought has no collenchyma on the exodermis of the stem wing,cells are larger,the ovoid chloroplast is large and outward,the vascular tissue is not developed.The number of columnar cells in the petiole wing,J.nudiflorum Lindl.in the sun and drought have more.There are also a large number of schizogenous aerenchyma near the phloem fibre in the petiole.In contrast to the J.nudiflorum Lindl.in the shade and drought.The epidermis cells are small and spongy tissue is not developed under the sun and drought.The epidermal cells are larger and have relatively developed spongy tissue under the shade and drought.The mesophyll cells above the main vein of the leaf evolved into a large number of palisade tissues.It enhances the plant's ability to capture and penetrate light,so as to improve the photosynthetic efficiency of plants and adapt to low light intensity environment.The J.nudiflorum Lindl.in the sun and drought of the drought environment relative to that in the sun and wet,evolved more to columnar cells containing chloroplasts on the end of the stem wing.Vascular tissue is developed and xylem tube hole chain is longer.The wood type is quasi ring porous wood,compared with diffuse-porous wood in the sun and wet,early wood pipe hole is bigger,which is benifit to absorb enough water for plants to adapt to the season of drought.The petiole phloem fibre wall of the J.nudiflorum Lindl.in sun and drought thickening remarkably in order to avoid plant wilting.There is schizogenous aerenchyma can store oxygen for metabolism.It is a landmark structure adapted to the drought environment.The blade cuticle is developed,the water retention capacity is enhanced and the stoma density is large.In the period of water supply shortage,the stoma is closed to reduce the water transpiration.All above characteristics are the evolutionary structure of plant opponent drought stress.The study of the Plant Print identification showed that: the J.nudiflorum Lindl.leaves apparent structures in different ecological environments of the test are anomocytic type,namely: no subsidiary cells.But the radial wall mosaic type of epidermal cells have differences,vertical wall pattern nearly flat type and light wave type,showed that the mosaic type of leaves epidermal cells vertical wall of the J.nudiflorum Lindl.in shade and drought is A,the mosaic type of leaves epidermal cells vertical wall of the J.nudiflorum Lindl.in sun and drought is G and the mosaic type of leaves epidermal cells vertical wall of the J.nudiflorum Lindl.in sun and wet is C.There are differences in the correlation direction and correlation degree between the morphological characteristics of leaves apparent structure.The optimal equation and fitting degree of regression analysis are different.These results confirmed that J.nudiflorum Lindl.under different environmental stresses,its leaves apparent structure in the process of evolution has not inconsistency that is the result of the interaction and coordination between the plant structure and the environment.Through the research on resistance of the J.nudiflorum Lindl.,provids evidence for the structural evolution of the first-hand plant antagonism in order to screen the plants for improving the ecological environment,which not only has theoretical significance,but also has practical application value.