Date of Award

5-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Plant and Environmental Science

Advisor

Bauerle, William

Abstract

Recent work has shown that stomatal conductance (gs) and net photosynthesis (Anet) are responsive to the hydraulic conductance of the soil to leaf pathway (Xp). However, no study has compared xylem anatomical differences under controlled conditions to directly evaluate the whole plant hydraulic and chemical response to manipulations of Xp. Two tree species with differing xylem structures were used to study the effect of systematic manipulations in Xp that elevated xylem hydraulic resistance. Simultaneous measures of gs, Anet, bulk leaf abscisic acid concentration, leaf water potential, and whole plant transpiration were taken under controlled environment conditions. Shumard oak, a ring porous species, and red maple, a diffuse porous species, were studied to investigate the short term hydraulic and chemical messenger response to water stress.The results indicated hydraulic resistance differences that may be attributed to the disparate xylem anatomy between the two species. This study also provides evidence to support the short term hydraulic signal negative feedback link hypothesis between gs and the cavitation threshold, as opposed to chemical signaling via rapid accumulation from root or leaf synthesized ABA.

Included in

Horticulture Commons

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