Unraveling the Effects of Plant Hydraulics on Stomatal Closure during Water Stress in Walnut
AUTOR(ES)
Cochard, Hervé
FONTE
American Society of Plant Physiologists
RESUMO
The objectives of the study were to identify the relevant hydraulic parameters associated with stomatal regulation during water stress and to test the hypothesis of a stomatal control of xylem embolism in walnut (Juglans regia × nigra) trees. The hydraulic characteristics of the sap pathway were experimentally altered with different methods to alter plant transpiration (Eplant) and stomatal conductance (gs). Potted trees were exposed to a soil water depletion to alter soil water potential (Ψsoil), soil resistance (Rsoil), and root hydraulic resistances (Rroot). Soil temperature was changed to alter Rroot alone. Embolism was created in the trunk to increase shoot resistance (Rshoot). Stomata closed in response to these stresses with the effect of maintaining the water pressure in the leaf rachis xylem (Prachis) above −1.4 MPa and the leaf water potential (Ψleaf) above −1.6 MPa. The same dependence of Eplant and gs on Prachis or Ψleaf was always observed. This suggested that stomata were not responding to changes in Ψsoil, Rsoil, Rroot, or Rshoot per se but rather to their impact on Prachis and/or Ψleaf. Leaf rachis was the most vulnerable organ, with a threshold Prachis for embolism induction of −1.4 MPa. The minimum Ψleaf values corresponded to leaf turgor loss point. This suggested that stomata are responding to leaf water status as determined by transpiration rate and plant hydraulics and that Prachis might be the physiological parameter regulated by stomatal closure during water stress, which would have the effect of preventing extensive developments of cavitation during water stress.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=148995Documentos Relacionados
- Nitric Oxide Induces Stomatal Closure and Enhances the Adaptive Plant Responses against Drought Stress1
- Exogenous abscisic acid inhibits the water-loss of postharvest romaine lettuce during storage by inducing stomatal closure
- Leaf Age as a Determinant in Stomatal Control of Water Loss from Cotton during Water Stress 1
- The Dependence of Stomatal Closure on Protein Synthesis
- The Dependence of Stomatal Closure on Protein Synthesis 1