Date of Award:

5-1967

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant Physiology

Committee Chair(s)

Herman H. Wiebe

Committee

Herman H. Wiebe

Committee

Gene W. Miller

Committee

H. P. Stanley

Committee

G. M. Baker

Committee

W. S. Boyle

Abstract

The effects of fluoride fumigation on Pelargonium zonale leaves and also sodium fluoride infiltration of leaf sections and Allium cepa roots were studied in vivo.

Anatomical studies of fluoride-injured leaves showed a total collapse of the margin of the injured leaf. In injured regions the upper epidermal cells were normal and were the last to be destroyed. Detailed study of the vascular region of leaves near the injured area and also petioles from severely injured leaves showed clogging of xylem vessels by tyloses. Clogging of sieve tubes occurred, presumably, due to deposition of callose substance on sieve plates of fluoride-affected leaves.

Histochemical observations of fumigated leaves showed increased peroxidase and cytochrome oxidase activities around the injured area of fumigated leaves. The greatest enzyme activity was observed in phloem region. In both cases the phloem region showed the presence of enzyme activity even after the complete collapse of adjacent parenchyma cells. Fluoride fumigation appears to stimulate these enzymes in vivo.

Succinic dehydrogenase was very sensitive to fluoride treatment. Enzyme activity was completely stopped in and near the injured area. Fluoride ion in solution caused decreased peroxidase and succinic dehydrogenase activities in P. zonale leaves and also A. cepa roots. Cytochrome oxidase activity in P. zonale leaves and A. cepa roots showed a marked increased enzyme activity at low concentrations of fluoride.

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