Assuming optical density to be a function of population density, colorimetric techniques were used to determine the effects of two growth regulator substances, indole-3-acetic acid and gibberellic acid, on the morphology and population dynamics of Eudorina elegans. A tube of culture medium without organisms was used as a reference point to calibrate the colorimeter. Chemically-treated cultures and soil-water control cultures were compared to the reference reading and growth curves were plotted. Colony counts were made at the termination of the experiment and comparisons were made with the colorimeter readings. Results demonstrated gibberellic acid to be a promoter of cell division and/or growth in concentrations below 75 ppm and to be inhibitory at concentrations of 75 ppm and above. Indole-3-acetic acid produced little effect on populations at low concentrations and was strongly inhibitory above concentrations of 5 ppm.
Proceedings of the Iowa Academy of Science
©1967 Iowa Academy of Science, Inc.
TePaske, E. Russell and Frank, Dale Robert
"Influence of Gibberellic Acid and Indole-3-Acetic Acid on the Morphology and Population Dynamics of Eudorina elegans,"
Proceedings of the Iowa Academy of Science, 74(1), 36-44.
Available at: https://scholarworks.uni.edu/pias/vol74/iss1/10