Date of Award


Degree Name

Master of Arts


Biological Sciences

First Advisor

Dr. Leo C. Vander Beek

Second Advisor

Dr. Richard W. Pippen

Third Advisor

Dr. Clarence J. Goodnight

Access Setting

Masters Thesis-Open Access


The short-term growth response of etiolated pea stem segments (Pisum sativum L., var. Alaska) was investigated using a high-resolution growth recording device. The immediate effect of treatment with indoleacetic acid (IAA) is an inhibition of growth. This inhibition lasts about 10 minutes and then the rate of elongation rises abruptly to a new steady rate about 4 times the rate of elongation before auxin treatment. This rapid steady rate of elongation, however, continues for only about 22 minutes before declining suddenly to a lower steady rate of growth about 2 times the rate of elongation before the addition of auxin. Pretreatment of the segments with cycloheximide or actinomycin strongly inhibits both phases of auxin promoted elongation without altering the length of the latent phase in response to the hormone. The triphasic nature of the growth response in relation to the IAA-oxidase system and a possible pathway for elongation is discussed.