A review of multiple biostimulant and bioeffector benefits of AMPEP, an extract of the brown alga Ascophyllum nodosum, as applied to the enhanced cultivation and micropropagation of the commercially important red algal carrageenophyte Kappaphycus alvarezii and its selected cultivars

Commercially manufactured extracts of a variety of seaweeds have been used extensively for several decades for the relief of abiotic and biotic stresses for (terrestrial) agricultural crops and horticulture, to improve yield and quality. However, the use of seaweed extracts for their beneficial properties, as applied to marine macroalgae, only began in the mid to late 2000s. Kappaphycus alvarezii is an important red seaweed on the coasts of tropical to sub-tropical waters, mainly because of the various applications of kappa carrageenan, which is the major industrial colloid extracted from this extensively cultivated biomass. Cultivation of this seaweed has brought economic benefits to tens of thousands of seaweed farmers in Southeast Asia and other minor producing countries. Recently, Ascophyllum (aka. Acadian) Marine Plant Extract Powder (AMPEP), a commercial seaweed extract from the brown intertidal, macroalga A. nodosum was used in steps taken during the micropropagation and field cultivation of K. alvarezii. The reasons for utilizing this treatment included addressing the current problems facing the industry, such as decreased productivity, loss of vigor and diminished crop quality. This was brought about by shortages in the availability of good quality propagules (seedlings) and also disease and endo-epiphyte infestations, which affected the ability to grow and harvest saleable biomass, thus decreasing the income, and therefore the interest and participation of the potential seaweed farmers (based on the factor of repetitive, drudge labor and their derived income per unit effort). This paper reviews studies on Kappaphycus including the use of AMPEP specifically and also some alternative extracts to mitigate both biotic and abiotic stressors, using examples from micropropagation, field cultivation, endophyte mitigation and impacts on the resulting carrageenan qualities. Taken together, this body of evidence provides proof of concept and very promising results which may lead to further studies more specifically to identify the modes of action and the metabolic pathways by which the complex AMPEP extract might improve stress tolerances in K. alvarezii in order to obtain higher productivity and enhanced quality characteristics (i.e., exposure to increasing surface seawater temperature, salinity fluctuations and photo-inhibitory irradiance as well as attacks by pathogenic and opportunistic organisms).