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ROOT CONTRACTION IN TRANSPIRING PLANTS
Author(s) -
FAIZ S. M. A.,
WEATHERLEY P. E.
Publication year - 1982
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1982.tb03391.x
Subject(s) - contraction (grammar) , soil water , dns root zone , water stress , root system , environmental science , water flow , plant root , water potential , chemistry , agronomy , botany , soil science , horticulture , biology , endocrinology
SUMMARY Experimental data published previously (Faiz and Weatherley, 1977) emphasized the existence of considerable hydraulic resistance in the perirhizal soil of rapidly transpiring plants. This was evident when soil water potential (Ψ s in the root zone was as high as −2 or −3 bars. In a further paper (Faiz and Weatherley, 1978) the hypothesis was put forward that it is the soil‐root interface which presents a high resistance to the flow of water through the soil‐plant system. This resistance, it was thought, could increase as a result of contraction of stressed‐roots, with the formation of vapour gaps between soil and root. In this paper we demonstrate that the root tissues may contract by as much as 25 % of their turgid volume when the water potential of the leaves (Ψ l ) falls to around −15 bars. Under such conditions the extensive formation of vapour gaps would be expected and a reduction of water stress should therefore follow if the gaps could be closed mechanically. Such closure was attempted by either squeezing or vibrating the soil mass containing the root system. Both of these treatments led to a temporary reduction in water stress in the plants and the existence of vapour gaps was thus supported.