LE3 .A278 2010

2010

Kristie, David

Acadia University

Bachelor of Science

Honours

Biology

Biology

Seaweed extracts are widely used in horticulture to promote plant growth and health. A species of kelp ( Macrocystis integrifolia Bory de Saint- Vincent) is harvested by West Coast Marine Bioprocessing Corp. ( Vancouver, BC) and used to produce a liquid seaweed extract called Kelpgrow. The objectives of this study were to determine levels of gibberellin- ( GA) and auxin- like activity in Kelpgrow and compare the effects of Kelpgrow to seaweed extracts produced by other companies. GA- and auxin- like activities were assessed using lettuce hypocotyl elongation and mung bean rooting bioassays respectively. Although physico- chemical analysis by NCR- IMB revealed very low levels of plant growth regulators in Kelpgrow, auxin- like rooting activity in Kelpgrow was equivalent to ca. 3.0x10- 4 M IBA, 1200 times higher than expected based on the physico- chemical analysis. Maximal effects of Kelpgrow on root mass and root number were found at concentrations of 1% and 2% respectively. Kelpgrow induced new roots primarily in the upper 3 cm of a 4 cm hypocotyl. GA- like activity was equivalent to ca. 2.2x10- 5 M GA3, 2200 times higher than expected. High levels of auxin- like activity and significant GA- like activity were present in a high molecular weight fraction ( HMW) of Kelpgrow (> 13, 000 MW) produced by dialysis. Two other seaweed extracts exhibited similar but distinct rooting behavior in mung bean rooting bioassays. Rooting activity was retained in a HMW fraction ( attained via dialysis) of one product but totally lost in the other. Overall these results indicate that GA and auxin- like activity in Kelpgrow occurs primarily in the HMW fraction, and is not related to the presence of GAs and auxins in the extract.

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https://scholar.acadiau.ca/islandora/object/theses:669