title: Relationships between stomatal behavior, xylem vulnerability to cavitation and leaf water relations in two cultivars of Vitis vinifera.
abstract: Current understanding of physiological mechanisms governing stomatal behavior under water stress conditions is still incomplete and controversial. It has been proposed that coordination of stomatal kinetics with xylem vulnerability to cavitation [vulnerability curve (VC)] leads to different levels of isohydry/anisohydry in different plant species/cultivars. In this study, this hypothesis is tested in Vitis vinifera cultivars displaying contrasting stomatal behavior under drought stress. The cv Montepulciano (MP, near-isohydric) and Sangiovese (SG, anisohydric) were compared in terms of stomatal response to leaf and stem water potential, as possibly correlated to different petiole hydraulic conductivity (k(petiole)) and VC, as well as to leaf water relations parameters. MP leaves showed almost complete stomatal closure at higher leaf and stem water potentials than SG leaves. Moreover, MP petioles had higher maximum k(petiole) and were more vulnerable to cavitation than SG. Water potential at the turgor loss point was higher in MP than in SG. In SG, the percentage reduction of stomatal conductance (PLg(s)) under water stress was almost linearly correlated with corresponding percentage loss of k(petiole) (PLC), while in MP PLg(s) was less influenced by PLC. Our results suggest that V. vinifera near-isohydric and anisohydric genotypes differ in terms of xylem vulnerability to cavitation as well as in terms of k(petiole) and that the coordination of these traits leads to their different stomatal responses under water stress conditions.
authors.affiliation: Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, 06121, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Tombesi
authors.forename: Andrea
authors.initials: A
authors.lastname: Nardini
authors.forename: Daniela
authors.initials: D
authors.lastname: Farinelli
authors.forename: Alberto
authors.initials: A
authors.lastname: Palliotti
mesh_terms: D003681:Dehydration; D018515:Plant Leaves / Q000502:physiology; D018547:Plant Stems / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology*; D018526:Plant Transpiration / Q000502:physiology*; D014197:Trees; D027843:Vitis / Q000502:physiology*; D014867:Water / Q000502:physiology*; D052584:Xylem / Q000502:physiology*
chemical_list: D014867:Water