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Abstract Detail

Water Relations

Voicu, Mihaela [1], Zwiazek, Dr. Janusz [2], Tyree, Mel [2].

Hydraulic conductance responses of bur oak (Quercus macrocarpa) leaves to light and inhibitor treatments.

The effects of irradiance and chemical inhibitors on leaf lamina hydraulic conductance (Klamina) were investigated in bur oak (Quercus macrocarpa Michx.) using a high pressure flow meter. In leaves collected from mature trees, lamina hydraulic conductance increased about three to seven fold when the leaves were exposed to high intensity irradiance (>1000 μmol m-2 s-1 photosynthetic photon flux density). When the leaf tertiary veins were cut open, Klamina increased by up to 23-fold and it was not sensitive to light. Following a 30-min exposure of leaves to high intensity light of different wavelengths, Klamina increased by about 160% in white light, about 100% in blue and green light, and less than 30% in amber and red light. The net CO2 assimilation rates were the lowest in leaves exposed to blue light and similar when the leaves were subjected to white, greed, red, and amber light of similar photosynthetic photon flux density (PPFD). Under white light, Kleaf light response saturated at about 150 μmol m-2 s-1 PPFD. Sodium fluoride (a general metabolic inhibitor), atrazine (a PSII photosystem inhibitor), and HgCl2 (an aquaporin blocker) also reduced light responses of Klamina. When ß-mercaptoethanol was added following mercury treatment, the response was totally suppressed. These results suggest that the effect of light on Klamina is controlled by the factors located outside of the leaf main veins, possibly through light-induced changes in the membrane permeability of mesophyll and/or bundle sheath cells. The light effect on Klamina appears to be dependant on the cell metabolism.

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1 - University of Alberta, Renewable Resources, 4-42 Earth Sciences Building, Emonton, Alberta, T6G 2E3, Canada
2 - University of Alberta, Renewable Resources

leaf lamina hydraulic conductance
sodium fluoride

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P09013
Abstract ID:894

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