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内聚力-张力学说的新证据
引用本文:李吉跃,高丽洪.内聚力-张力学说的新证据[J].北京林业大学学报,2002,24(4):135-138.
作者姓名:李吉跃  高丽洪
作者单位:1. 北京林业大学资源与环境学院,国家林业局干旱半旱地区森林培育及生态系统研究重点开放性实验室;2. 云南西双版纳州科技局科技情报所
基金项目:国家自然科学基金;30070637;
摘    要:虽然内聚力-张力学说已经建立了一个多世纪,但要完全接受它仍有一些问题,因为它的一个推论是很难证实的,即木质部导管中存在大的负压.特别是近年来木质部压力探针和Z型管试验的结果表明,引起空穴的木质部压力仅在-0.5 MPa以上. 有人根据这一结果认为必须对木质部水分运输的内聚力-张力学说加以修正. 但是,目前又有两个研究小组应用相似改良的Z型管方法测定了产生空穴的木质部压力. 他们的结果显示,不同树种木质部导管保持水分传导的压力范围在-1.2 MPa到-3.5 MPa以下. 这表明树木木质部导管中存在较大负压,从而有力支持了内聚力-张力学说.

关 键 词:内聚力-张力学说  负压  空穴

New evidence for cohesion tension theory
Li Jiyue, Gao Lihong. College of Resources and Environment,Beijing For. Univ.,P. R. China..New evidence for cohesion tension theory[J].Journal of Beijing Forestry University,2002,24(4):135-138.
Authors:Li Jiyue  Gao Lihong College of Resources and Environment  Beijing For Univ    P R China
Institution:Li Jiyue, Gao Lihong. College of Resources and Environment,Beijing For. Univ.,100083,P. R. China.
Abstract:Although the cohesion tension theory has been well established for more than a century, some problems have stood in the way of its complete acceptance because its corollary is difficult to prove: large negative pressures exist in xylem conduits. Especially recent xylem pressure\|probe and Z\|tube experiments suggest that cavitation limits xylem pressures to above-0 5MPa, which may necessitate modification of the cohesion\|tension theory of xylem transport. Now another two groups used a similar modifying Z\|tube method to determine negative pressures causing cavitation in intact xylem conduits. They show that xylem conduits of trees remained water\|filled and conductive to species specific pressures ranging from-1 2 to below-3 5 MPa, supporting the cohesion tension theory as the primary mechanism for water transport in trees.
Keywords:cohesion  tension theory  negative pressure  cavitation
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