植物体内水分长距离运输的生理生态学机制

PHYSIOLOGICAL AND ECOLOGICAL MECHANISMS OF LONG-DISTANCE WATER TRANSPORT IN PLANTS: A REVIEW OF RECENT ISSUES

植物体内长距离水分运输是植物生理生态学研究中的一个重要问题,长期为植物生理学家和生理生态学家所关注。木质部探针技术的问世,掀起了近年来植物生理学界最为激烈的一场争论。提出了已经有100多年,风行40年的内聚力-张力(Cohesion-Tension,C-T)学说受到质疑。随后维护派和质疑派围绕木质部探针技术、压力室技术(C-T理论的主要支撑实验技术)的可靠性展开辩论。进一步从物理学原理和各种实验上就C-T理论的3个支柱(木质部导管或管胞中巨大的张力、沿树高的压力梯度、连续水柱)进行争论。这场争论似暂告一段落,C-T理论没有被推翻,但仍留有问题期待以后的研究。

Long-distance water transport in plants is an important issue in plant physiology and eco-physiology. The recent development of the Xylem Pressure Probe for direct measurement of pressure in individual xylem elements of intact, transpiring plants elicited challenges to the long-standing, widely accepted Cohesion-Tension （C-T） Theory. These challenges instigated debate in the field of plant physiology over mechanisms of long-distance water transport. The challengers and proponents of the C-T theory mutually criticized the Pressure Bomb and the Xylem Pressure Probe technology, and they debated over all three elements of C-T theory （high tension in xylem units; pressure gradients over tree height; the continuous water column in xylem vessels） by reviewing literature and providing physical bases. The debate has cooled down. As a result, the C-T theory has not been discredited while the raised questions in the debate remain mainly unanswered and call for future researches.