Date of Award:

5-1973

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

W. S. Boyle

Committee

W. S. Boyle

Committee

Orson S. Cannon

Committee

Wade G. Dewey

Abstract

The effects of Vitavax fungicide (2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin) on meiotic chromosomes of rye (Secale cereale) and mitotic chromosomes of onion (Allium cepa) and rye were observed.

The principal aberrations recorded in pollen mother cells of rye were: 1-4 univalents at metaphase I; sticky bridges at telophase I; and micronuclei and misshapen nuclei at the quartet stage.

The principal aberrations recorded in root tip mitoses in onion and rye were: chromosome fragmentation, disintegration, clumping, aggregation and inhibition of mitosis.

All meiotic phases were significantly affected by 1,000, 5,000,10,000, 33,300, 66,600 ppm Vitavax at the 48, 72, and 96 hour application periods. Heavy application rates (10,000 ppm or more, 96 hours) induced disintegration of pollen mother cells. Spikes grown from seeds treated at recommended field rate (33,300 ppm) and double the field rate (66,600 ppm) showed no significant deviation in chromosomal behavior from controls.

Mitotic cells of onion and rye showed aggregation of chromosomes and inhibition of mitosis at 12 hours, 10,000 ppm, while clumping, fragmentation and disintegration occurred in onion at 48 hours, 66,600 ppm.

Paraffin sections of root tip meristems treated for 48 hours with 10,000 ppm Vitavax disclosed irregularly shaped nuclei and mitoticinhibition in onion and marked splitting of tissues and cell collapse in primary meristems of rye.

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