Bioactive seaweed extracts as biostimulants of growth and protection of plants

Abstract

Seaweed extracts are widely used in agriculture as plant growth biostimulants and constitute an ecological alternative to the excessive consumption of synthetic agrochemicals. These bioproducts are complex mixtures of several bioactive compounds such as plant growth regulators, polysaccharides, phenols, amino acids, sterols, betaines, vitamins, macro and microminerals. Its application in the production of different crops generates a wide spectrum of positive responses in the soil-plant system. However, the biostimulatory potential of these formulations has not been fully exploited due to the limited knowledge about their mechanisms of action in plants. This review aims to analyze the perspectives of seaweed as a source of bioactive extracts for the promotion of plant growth and crops protection. The main compounds with biological activity in seaweed extracts and the methods for their extraction are described. In addition, the hormetic effects of these bioproducts on seed germination, root-system development, rhizospheric microbiome, crop yield and quality, plant nutrient uptake and assimilation, plant metabolism and physiology are analyzed; as well as in the mitigation of abiotic stress and the management of pests and diseases. Finally, the predominant metabolites in Cuban seaweed extracts for the development of new bioproducts for agricultural purposes are described.