Date of Award

1978

Degree Type

Thesis

Degree Name

Master of Science in Botany

Department

Botany

First Advisor

R. Hauke

Abstract

This study investigated the effects Sevin (1-naphthyl N-methylcarbamate) had on the morphology and root anatomy of soybeans (Glycine max (L.) Merr.).

Morphological observations revealed that as the concentration of Sevin increased, the cotyledons, hypocotyl and epicotyl decreased in size. Absence of a pigment (presumably anthocyanin) normally present in the petioles and hypocotyl, was noticed at all applications of Sevin. Emergence of primary and trifoliate leaves was delayed as the concentration of Sevin increased. Increased Sevin concentrations produced thin, white roots with numerous laterals. With increased concentrations, purple pigment appeared on both taproots and lateral roots.

Growth rates of roots, when analyzed by Duncan's Modified Multiple Range Test, were not significant between 2, 9 and 19 ppm of Sevin, but were significant at the 1% level for 21, 25 and 55 ppm of Sevin.

Roots of treated soybeans exhibited development of lateral root prirnordia close to the root apex. This suggests that the cells failed to elongate in advance of differentiate on. There appeared to be no change in the quiescent center for all Sevin concentrations. Noticeable vacuolization of cortical, stelar, epidermal and root cap cells occurred at 21, 25 and 55 ppm of Sevin. At increased Sevin concentrations, the root cap was usually sloughed off or was lacking.

An autoradiographic study indicated that the translocation of 14c-sevin was predominately apoplastic with possible accumulation of 14c-sevin into the symplast.

Morphological and anatomical analyses revealed few or no appreciable differences at 2, 9 and 19 ppm of Sevin, but at 21, 25 and 55 ppm, noticeable change in root structure did occur.

Sevin has low mammalian toxicity, short half life and at low threshold concentrations does not produce visible anatomical or growth changes. These properties make Sevin one of the most useful insecticides available today.

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