3
Jun

Seaweeds are more than cytokinins and auxins

For centuries, seaweeds have been used along coastal areas as sources of rich organic matter in soils. In recent decades, Ascophyllum nodosum marine plant extracts have played a significant role within mainstream agriculture as an increasingly important tool to help crop growth and development.

Ascophyllum nodosum is widely regarded as the most used and researched seaweed species in agriculture. The brown algae, commonly known as Norwegian kelp, grows within the intertidal zone, along the North Atlantic coastline. Harvested by hand, these hardy sea plants serve as the raw resource for the production of soluble extracts for use in plant agriculture.

For many years the mainstream thinking was that the cytokinins and auxins in the extracts are the elements that are responsible for the bulk of the physiological benefits in crops. Further research has now shown that Ascophyllum nodosum extracts also increase the production of endogenous cytokinin and auxin plant hormones. This is measured by both an increase in transcript production as well as the hormones themselves.

Little spoken about is the other product ingredients and links to efficacy or mode of action.

Seaweed

Alginic acid

As the main structural carbohydrate of Ascophyllum, this polymer will be liberated from the cell wall of the algae into water-soluble salt forms during the extraction process. It will also be cleaved to some degree to constituent oligosaccharides and monomer acids during processing. These acids and oligosaccharides are strong mineral chelators and can help with nutrient availability/delivery. As highlighted below, oligosaccharides are thought to be important signalling molecules in plant physiology.

Laminarin

Historical information has shown Laminarin to be a component of Ascophyllum and as such it would be liberated into the subsequent extract. Laminarin is well documented in plant immune stimulation purposes.

Oligosaccharides

A large percentage of the organic matter fraction of Ascophyllum extracts is comprised of various poly- and oligosaccharides. These carbohydrates are well recognised as elicitors and stimulators of plant defence mechanisms, and the effects are well documented in scientific literature.

Organic acids

As part of overall plant carbohydrates, the organic acid fraction is important for several reasons. Most notably, as a source of energy production as well as for precursors for some hormones (e.g. mevalonic acid). We have evidence for this in our research reports.

Mannitol

Comprising up to 5% of the dry weight of Ascophyllum, mannitol is a sugar-alcohol that has been widely shown to be an osmotic regulator in plants. Mannitol can act to protect and adjust cell-water status in abiotic stress and water-related stress issues. It is also involved in inorganic nutrient chelation and can act to improve nutrient availability similar to alginic acid.

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Betaines

These quaternary-ammonium compounds are well known as cell membrane protectants and osmotic adjustors. They have also been positively identified in Acadian extracts and are very important in abiotic stress mitigation in plant cells.

Fucose-containing polysaccharides (FCPs), sulphated polysaccharides such as FCP, ulvan and carrageenan are unique to plants growing in the marine environment. Unique to brown algae such as Ascophyllum, FCPs have been demonstrated to have many effects such as antiviral, antioxidant and protective capabilities. Their use in animal physiology has been well documented and their effects in plant systems are beginning to be explored.

Amino acids

Although the protein content of Ascophyllum is relatively low, what protein is present will be extracted and broken down to constituent amino acids and peptides during processing. The compounds can serve as building blocks in plant development and microbial activity in the rhizosphere, but Acadian extracts should not be considered as a major source of these compounds.

Micronutrients

Many micronutrients including iron, zinc, boron and manganese are present in Ascophyllum, and have been quantified and established in the resulting extract. The quantities and concentration are very low when evaluated from a fertiliser standpoint. However, any amounts can be helpful and they may be present as organically chelated forms, potentially making them more available to plants.

Macronutrients

Macronutrients and secondary macronutrients such as potassium, calcium, magnesium and sulphur have also been shown to be present in Acadian extracts. Again, looking at typical product application rates, the resulting agronomic input from a fertiliser standpoint is very low. However, any amount can be helpful. Other than the K (coming from the alkali used as a processing aid), all the macro- and micronutrients originate from the fresh Ascophyllum – we do not fortify our extracts with fertilisers.

As can be seen from the above, seaweed extracts can be considered as a “soup” which contains many compounds which act individually or in combination to help crops attain their maximum potential.

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