Date of Award:

5-1969

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Horticulture

Committee Chair(s)

J. LaMar Anderson

Committee

J. LaMar Anderson

Committee

W. S. Boyle

Abstract

Seeds of oat, green foxtail, squash and tomato were germinated in soil treated with different levels of DCPA (dimethyl 2, 3, 5, 6-tetrachlorote-rephthalate). The concentrations used varied according to the sensitivity of the plants to the chemical.

The response of oat and foxtail to DCPA was similar. The growth of booth root and shoot was reduced. This reduction was directly related to the concentration of DCPA. Anatomical studies showed that cells in the shoot and root meristems of treated plants were completely disarranged and that some of the cells of these regions were hypertrophied. Some clumping of nuclei was observed in oat shoot tip. Foxtail showed a stimulation of shoot growth at 2 ppm level of DCPA. In both grass species differentiation seemed to start nearer the apex in treated plants and was highly irregular. Histochemical tests showed that the amount of starch, proteins and nucleic acids decreased with an increase of DCPA concentration. The walls of shoot meristem cells were thickened. The size and number of chloroplasts were increased in the cells of first true leaves. Seeds of treated plants seemed to contain more starch and protein.

In squash, even though the shoot and root growth was reduced, no anatomical or histochemical differences could be observed except that the amount of starch in shoot meristems was slightly increased with increased concentrations of DCPA and that cotyledons of treated plants contained more starch and protein. These cotyledons also contained more and larger chloroplasts.

The cytogenetical studies failed to show any differences in the mitotic index of plants studied. No abnormal chromosome behavior was observed.

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