Date of Award:

5-1-2000

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Keith A. Mott

Committee

Keith A. Mott

Committee

Martyn Caldwell

Committee

Richard Mueller

Abstract

The objective of this project was to study the interactions among adjacent stomata in response to environmental conditions. Fully expanded and intact leaves from cocklebur (Xanthium strumarium L.) plants grown in a controlled-environment greenhouse were clamped to a microscope stage for observation. Changes in stomatal apertures in response to changes in photon flux density (PFD) and evaporative demand (Δw, the water vapor mole fraction gradient between leaf and air) were measured. Increases in PFD elicited no significant coordinating responses among stomata. Responses of stomata to decreases in PFD were suggestive of coordination, but not conclusive. However, stomatal responses to changes in Δw indicated that coordinated responses among stomata occur. In response to increasing the Δw, the target stoma opened (wrong-way response) and then closed. Adjacent stomata exhibited the same response; however, the magnitude of change in aperture varied. The results obtained in this study showed that short distance interactions among stomata are possible in response to humidity perturbations. These results indicated that hydraulic interactions play a major role in coordinating responses among stomata within an areole. Stomata measured in each experiment were within the same areole. Interactions among stomata separated by veins were not observed.

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