title: Plant water status and hydraulic conductance during flowering in the southern California coastal sage shrub Salvia mellifera (Lamiaceae).
abstract: OBJECTIVE
  Plant water status during flowering is important for plant reproduction, but the physiology of floral water use is not well understood. We investigated plant water status in relation to leaf and floral physiology in naturally occurring individuals of a semiarid shrub, Salvia mellifera E. Greene.
  
  
  METHODS
  We measured stomatal (g(s)) and corolla (g(c)) conductance to water vapor, transpiration from leaves (E(leaf)) and corollas (E(corolla)), leaf-specific hydraulic conductance (K(H)), bulk shoot water potential (Ψ(shoot)), and shoot water content on irrigated and control plants to analyze whether water was limiting to leaf and floral water use.
  
  
  RESULTS
  Experimental irrigation caused a 203% increase in soil moisture content, a 20% increase in predawn Ψ(shoot), a 29% increase in midday Ψ(shoot), and a 92% increase in K(H). Floral and leaf gas exchange did not respond significantly to water addition, indicating that rates were at seasonal maxima and not limited by water availability. Total daily water use by corollas was ∼20% of total shoot water use. There were no significant differences in total daily shoot water use with water addition. Mean shoot water content (5.07 g) was close to mean daily shoot water use (6.71 g), indicating that the equivalent of total shoot water content turned over every 0.76 d.
  
  
  CONCLUSIONS
  These results demonstrate that although irrigation improved whole-plant hydraulic conductance, gas exchange was not limited by water availability. Additionally, the high water use of flowers in this species might limit future flowering and reproductive success during dry years.
authors.affiliation: Department of Biological Sciences, San Jose State University, San Jose, California 95192, USA.
authors.forename: Susan C
authors.initials: SC
authors.lastname: Lambrecht
authors.forename: Louis S
authors.initials: LS
authors.lastname: Santiago
authors.forename: Caroline M
authors.initials: CM
authors.lastname: DeVan
authors.forename: J Carlos
authors.initials: JC
authors.lastname: Cervera
authors.forename: Cara M
authors.initials: CM
authors.lastname: Stripe
authors.forename: Lee A
authors.initials: LA
authors.lastname: Buckingham
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Pasquini
mesh_terms: D057914:Agricultural Irrigation; D002140:California; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology*; D005740:Gases / Q000032:analysis; D008834:Microclimate; D008855:Microscopy, Electron, Scanning; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D018520:Plant Shoots / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology / Q000648:ultrastructure; D018526:Plant Transpiration; D027544:Salvia / Q000033:anatomy & histology / Q000502:physiology*; D012621:Seasons; D012987:Soil / Q000032:analysis; D014867:Water / Q000502:physiology*
chemical_list: D005740:Gases; D012987:Soil; D014867:Water