RESEARCH / 10
HARNESSING NATURAL PRODUCTS
FROM THE SEA FOR USE IN HORTICULTURE In this article, Karen O’Hanlon describes the numerous trials, using seaweed as a crop biostimulant, taking place across Ireland
A number of natural marine products found off the coast of Ireland have a role to play in plant and soil health.
SEAWEED
Seaweed (Ascophyllum nodosum and Laminaria digitata) has multiple benefits in terms of land management. ● The better-known attributes of seaweed are as a biocontrol and biofertiliser in helping to improve roots, nutrition and the quality of crops by supplying vitamins and minerals whilst also producing phytohormones that act as biostimulants to encourage immunity to disease, healthy growth and colour. ●S eaweed can absorb as much CO2 as trees and hence can contribute to CO2 sequestration. Carbon sequestration is the process by which CO2 is removed from the atmosphere and held in solid or liquid form; Plants can absorb CO2 during growth and store it in different tissues. The most important tissue for
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carbon sequestration is the root. Good organic practices encourage healthy soil-root interactions with the accumulation of microbial life around the root. ●M any biofertilisers on the market encourage such symbiosis between soil life and root. Seaweed as a foliar spray activates the plants own growth and protection systems to produce plant growth regulators, phytohormones, to protect from diseases and biomolecules to counteract drought, heat and frost. Numerous progressive wholesale horticulture growers in Ireland are using seaweed as a biostimulant (Seaweed is currently classified as a biostimulant and does not need to be registered as a plant protection product) at a 1:200 dilution during watering and enriching further with microbial mixes (including Bacillus subtilis and Pseudomonas fluorescence) to control root issues such as Rhizoctonia and Fusarium. Chitin is found in the skeletons of crabs and can act as a food source for chitinase-producing organisms. Once chitin is ingested and the population of chitinolytic producing
HORTICULTURECONNECTED / www.horticultureconnected.ie / Summer 2021
