The Study On Anatomical Structure And Drought-resistance Of Five Kinds Of Ulmaceae Plant

Paraffin-section technique and xylotomy and optics microscopy were adopted to make scientific researches on anatomical structure comparison and drought-resistance for the branch-woods and leaves of five kinds of Ulmaceae plants developing on droughty area, the five species of Ulmaceae Plants were Ulmus japonica (Rehd.) Sarg. var. suberosa (Turcz.) S. D. Zhao, U1mus macrocarpa var. mongolica Liou et Li, Ulmus macrocarpa Hance, Hemiptelea davidii (Hance)Planch. and Ulmus pumila Linn.. The results show that Ulmaceae Plants usually take on a lot of characteristics of drought-resistance under droughty circumstances: the cuticle gets thick, palisade parenchymas turn developed, stomas are numerous and distribute on nether epidermis, some epidermis cells dilate and contain viscousness etc. Structural evolvement of these xerophils puts the importance on five kinds of Ulmaceae Plants equally matching with droughty adversity. Above all, the paper selects the structures which relate to drought- resistance of five kinds of Ulmaceae as parameter, and carries through variance analysis and multiple comparison in order to make impersonality estimate on magnitude of drought- resistance of five kinds of Ulmaceae plants.In analysis of the relationship between structural parameter of leaf blade and drought- resistance, it chose leaf blade thickness, palisade parenchyma thickness, the ratio of palisade parenchyma thickness to spongy parenchyma thickness, upper and nether cuticular layer thickness of epidermis cell , upper and nether epidermis cell thickness and radial diameter of costate vessel which amount to eight structural parameters as drought-resistance guide line to make measure; in leafstalks, cuticular layer thickness of epidermis cell and epidermis cell thickness and radial diameter of xylem vessel were chosen to be scaled; in branch-woods, it selected wood fiber wall thickness, wood fiber inner diameter, and vessel pore radial diameter of early wood on transverse section as drought-resistance guide line to survey; by variance analysis, the result reveals that all kinds of structural parameters have mighty discrepancy except costate vessel radial diameter that is not remarkable difference, then by multiple comparison, it can be known that structural parameters of tissue regarding as drought- resistance guide lines, their acuity have high-low difference.The highest acuity guide lines of drought-resistance are leaf blade thickness, palisade parenchyma thickness, cuticular layer thickness of leafstalk epidermis cell, leafstalk epidermis cell thickness, and wood fiber wall thickness; higher acuity guide lines are the ratio of palisade parenchyma thickness to spongy parenchyma thickness, cuticular layer thickness of upper and nether epidermis cell of leaf blade, leafstalk xylem vessel radial diameter, tress wood fiber inner diameter, and radial diameter of early wood vessel pore; accessorial guide line are upper and nether epidermis cell thickness of leaf blade.Structures compared and data analyzed at last show that drought- resistance magnitude of five Ulmaceae plants on leaves and branch-woods is U. japonica (Rehd.) Sarg. var. suberosa (Turcz.) S. D. Zhao> U. macrocarpa var. mongolica Liou et Li>U. macrocarpa Hance > H. davidii (Hance)Planch. >U. pumila Linn.