Publication Date


Advisor(s) - Committee Chair

David Coffey, James Martin, James Worthington

Degree Program

Department of Agriculture

Degree Type

Master of Science


This investigation represents one of the first electron microscopic studies on determining the mode of action of the chemical herbicide sethoxydim, 2-[-1-(ethoxydimino)butyl] -5-.2-(ethiothio)propyl]-3- hydroxy-2-cyclohexen-1-one. Samples were excised from the intercalary meristem of johnsongrass (Sorghum halpense) at time intervals of 1,3, 6,12,24,36,48,60, and 72 hours and examined using electron microscopy. Transmission electron micrographs revealed that cellular activity shows alterations or abnormalities as early as six hours. Membranes show deterioration at this time and chloroplasts contain densely staining starch granules. As time intervals increase, cellular degradation becomes more evident. Nuclear membranes extend outward into the cytoplasm in various types of cells. After 72 hours, the protoplasm demonstrates plasmolysis. The cell walls, plasma membranes, and plasmodesmata are also influenced by the sethoxydim treatment. Scanning electron micrographs were studied for the effects on vascular bundles and the surrounding tissue. The results were similar to those found by transmission electron miscroscopy.


Agricultural Science | Agriculture | Life Sciences | Plant Sciences | Weed Science