Abstract Detail

Physiological Section

Del Rio, Samuel R [1], Hluza, Christine [2], MacKinnon, Evan D. [2], Parker, Jeffrey [2], Pratt, R. [3].

Hydraulic conductance is coordinated at the leaf and stem levels among chaparral shrubs.

Xylem hydraulic supply is crucial for maximizing CO2 uptake at the leaf level. Few studies have examined the link between stem level hydraulic capacity as it related to leaf level hydraulic uptake and transpiration. We examined stem transport efficiency (xylem and leaf specific hydraulic conductivity) and leaf hydraulic conductance. Leaf hydraulic conductance was measured on detached illuminated leaves as the steady state rate of water uptake through petioles and the water potential driving force was measured with a pressure chamber on matched leaves. Maximum net carbon assimilation was measured at about 9 AM during the growing season while plants were hydrated. We sampled 12 chaparral shrubs, 6 evergreen and 6 deciduous, grown in a common garden in Bakersfield, California. We found the leaf conductance per unit mass was positively associated with both maximum and native stem specific conductivity. Leaf specific conductivity of stems was positively associated with stomatal conductance of leaves. Taken together, these relationships indicate that stem supply of water is coordinated with leaf liquid and vapor phase water movement. Leaf hydraulic conductance per mass was positively associated with carbon assimilation per mass, and likewise, leaf conductance per area was positively associated with carbon assimilation per area. Stem leaf area to xylem area ratio was negatively associated with net carbon assimilation per unit area. Our data supports a strong coordination between liquid conductance through stems and leaf liquid and vapor conductances. Stem conductivity was not significantly linked to maximum assimilation rates suggesting that factors other than stem water supply and stomatal limitation were important determinants of carbon dioxide uptake.

Broader Impacts:

1 - California State University, Bakersfield, Biology, 9001 Stockdale Hwy., Bakersfield, California, 93311, United States
2 - California State University, Bakersfield, 9001 Stockdale Hwy., Bakersfield, California, 93311, United States
3 - CALIFORNIA STATE UNIVERSITY BAKERSFIELD, DEPARTMENT OF BIOLOGY, 9001 Stockdale Highway, Bakersfield, CA, 93311-1099, USA

Keywords:
leaf hydraulics
stem hydraulics
chaparral
assimilation
common garden.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Number: PPS004
Abstract ID:812
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize