Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate


LaMar Anderson


Peas (Pisum Sativum L. Var Alaska) were allowed to absorb calcium and magnesium chloride for 8 hours and then were germinated in a potassium phosphate buffer pH 6.5 for 40 hours. Peas were then treated with 0, 0.1, 0.3, or 0.5 ppm dicamba (3,6-dichloro-o-anisic acid) and harvested at 24, 48, and 72 hour intervals. The following determinations were recorded: Root elongation, nuclear volume, and anatomical modifications.

Root elongation recordings showed that dicamba prevented normal root elongation. Treatments induced very short thick primary roots.

Measurements of nuclear volume indicated that all herbicide concentrations were able to reduce the total volume. Several other compounds, (chloramphenicol, actinomycin D and colchicine), were introduced to better characterize the actions of dicamba. Chloramphenicol and colchicine were responsible for nuclear volume reductions.

Dicamba induced major anatomical alterations of treated pea roots. In the region 1 millimeter from the root tip, cortical cells were induced to divide more profusely. The diameter of treated roots exceeded that of untreated root tips.

In the region 3 millimeters from the root tip, excessive cellular division and swelling resulted in cortical damage.