Seaweed extract is often high in cytokinins and auxins, both of which are a class of plant growth improvers. Consequently, a number of companies outside the UK sell seaweed extracts as a natural fertiliser, which can be used to promote plant growth.
Uist Asco Ltd produce dried Ascophyllum Nodosum, and are now looking to enter the liquid seaweed extract market. A 2013 Algal SPARK award funded a project with the Biorenewables Development Centre (BDC) which developed methods for analysing the levels of plant growth promoters cytokinins and auxins in seaweed juice produced by Uist Asco.
The project demonstrated that chemical analysis was not the most appropriate method as cytokinins and auxins are a class of compound that can widely range in size and structure. Further work would be required to prove that bioassays can be used to determine the level of cytokinins and auxins, as a group, in seaweed juice. As bioassays can be long and laborious, alternative option would be to undertake simple growth trials using fast-growing plants to evaluate the growth promoting properties of the seaweed extracts.
The project also covered investigations into extraction from raw seaweed, which is challenging as extreme temperature and pH conditions destroy the cytokinins and auxins. The team looked at the effect on the seaweed juice of a range of methods from simple pressing, through pH and enzymatic extractions. The final step investigated novel systems for delivery of the seaweed juice. A range of biorenewable solid materials were trialled as solid supports for slow release application of seaweed juice to plants.