In order to investigate if plant hydraulic conductance is reduced under drought conditions via an ABA-related mechanism a water stress experiment was carried out using split-rooted (s-r) grapevines. In addition, the inversion of shoot growth orientation was imposed to reduce plant hydraulic conductance independently of soil water availability and thus of the putative ABA root-generated stress message. As expected, water stress imposed to split roots affected ABA accumulation. ABA drought- stress message negatively affected stomatal conductance and transpiration, but it modified neither leaf and stem water potentials, nor whole-plant hydraulic conductance. When hydraulic conductance was reduced in split-rooted shoot-inverted (s-r/s-i) grapevines, leaf and stem water potentials decreased, without changes in ABA accumulation, stomatal conductance and transpiration rate. Neither ABA drought-stress message modified plant hydraulic conductance, nor plant hydraulic conductance impaired by the shoot growth inversion decreased ABA delivery to the leaves. However, leaf growth was depressed in s-r/s-i grapevines. The fact that no interactions between ABA stress messages, caused by split-root technique, and hydraulic constraints to sap flow, cause by shoot inversion, were necessary to impair leaf growth suggests that the target of ABA and hydraulic-limitation effects on leaf expansion are not the same.
Whole-plant hydraulic conductance and root-to-shoot flow of abscisic acid are independently affected by water stress in grapevines
2002
Abstract
In order to investigate if plant hydraulic conductance is reduced under drought conditions via an ABA-related mechanism a water stress experiment was carried out using split-rooted (s-r) grapevines. In addition, the inversion of shoot growth orientation was imposed to reduce plant hydraulic conductance independently of soil water availability and thus of the putative ABA root-generated stress message. As expected, water stress imposed to split roots affected ABA accumulation. ABA drought- stress message negatively affected stomatal conductance and transpiration, but it modified neither leaf and stem water potentials, nor whole-plant hydraulic conductance. When hydraulic conductance was reduced in split-rooted shoot-inverted (s-r/s-i) grapevines, leaf and stem water potentials decreased, without changes in ABA accumulation, stomatal conductance and transpiration rate. Neither ABA drought-stress message modified plant hydraulic conductance, nor plant hydraulic conductance impaired by the shoot growth inversion decreased ABA delivery to the leaves. However, leaf growth was depressed in s-r/s-i grapevines. The fact that no interactions between ABA stress messages, caused by split-root technique, and hydraulic constraints to sap flow, cause by shoot inversion, were necessary to impair leaf growth suggests that the target of ABA and hydraulic-limitation effects on leaf expansion are not the same.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
