Dixon on...Benefits of seaweed extracts confirmed by latest science

Seaweed extracts are valuable promoters of biocontrol. They stimulate benign soil and foliar microbes, which help repel plant pathogenic bacteria and fungi.

Such enhancement of soil health is now a key principle for environmentally friendly crop husbandry. Healthy soils contain greater variety and numbers of benign microbes, especially bacteria. These in turn stimulate root activity and combat pathogens. 

Greater root activity probably results from their increased production of growth hormones. Biocontrol of pathogens results from enhanced competition for resources and the production of chemicals that inhibit pathogen growth. 

Knowledge of these effects stems from industrially funded research worldwide, showing that the centuries-old claims for soil conditioning effects of seaweed are scientifically bona fide. More widely, seaweed extracts stimulate seed germination, increase stress tolerance, enhance photosynthetic efficiency and improve quality in top fruit.

Proving cause and effect is the major business problem. Patent protection and safeguarding intellectual property rights are difficult. An absence of direct linkage between a specific constituent in the extract and resultant husbandry advantages flaws product protection. These difficulties stem from the variability of the raw material and from the use of several extraction processes. Nonetheless, this does not inhibit publicity and market expansion. 

Biocontrol benefits from several modes of action that can be used in an integrated manner. Extending the spectrum of biocontrol systems and including seaweed extracts help delay the development of tolerances towards specific agents. 

Raw kelp is heavy because of its high water content, so it is dried rapidly after harvesting. Resultant industrial feedstock has a wide range of uses for pharmaceuticals, food additives and agriculture, with worldwide sales of US $6.5bn. Most harvesting takes place in China and Indonesia from warm tropical seas, although Norway retains a market presence. 

Recently, there has been an expansion of interest in British production off the Scottish west coast. Such developments would necessitate substantial investment in industrial-scale driers. The resultant product would also require specific high-quality properties enabling competition with well-established suppliers elsewhere. These will most likely stem from uses in locations that have stringent environmental constraints. For example, suitability for very valuable aquatic horticultural crops such as wasabi could offer opportunities.

Professor Geoffrey Dixon is managing director of GreenGene International

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