Potential Effect of Plant Growth Regulators in Two Seaweed Products

Abstract

Seaweeds and seaweed products have been applied in vegetable production systems for many years. This is because seaweeds have beneficial effects in vegetable production systems. However, the mechanism by which seaweed can elicit the growth and development response is still not fully understood. Mineral nutrient concentrations are commonly too low to be effective, and plant growth regulators (PGR) have been suggested as a causal factor. PGR activity in two seaweed products (Maxicrop® and Seasol®) was investigated using field pea ('Pisum sativum' L.) bioassays. Treatments included a control, standard concentrations of the seaweed products, ashed seaweed products, auxin, cytokinin, gibberellin and mineral nutrients (matched to each seaweed product). The results obtained show that the seaweed products have potential plant growth regulator activity rather than a mineral nutrient effect alone. Ashing reduced the root growth effect of Seasol® but not Maxicrop®. Seasol® performed better than Maxicrop® based on the root and shoot length.