Phycobiostimulants: Next-Generation Sustainable Agricultural Inputs

Plant biostimulants are a novel class of naturally derived agricultural inputs. The grouping of categories within the regulatory term “biostimulant” contains disparate inputs, such as humates, amino acids, bacteria, and algal extracts (i.e., many extraction processes applied to a relatively small group of selected seaweeds/microalgae). All seem to have the ability to improve the health and abiotic stress resistance of the treated plants. Even extracts of seaweeds (phycobiostimulants) are considerably different from one another (they are not all the same yet commonly referred to as seaweed extract, even in peer-reviewed publications), and current commercial offerings are available from a select group of green, red, and brown seaweeds. Commercial formulations combine different seaweed extracts and increasingly leverage synergies by blending biostimulants with other agricultural inputs and agrochemicals. Extensive research highlights that various algal-based extracts can effectively support both abiotic and biotic stress resistance when applied to both treated terrestrial plants and other cultivated algae. This article explores the scientific nuances of phycobiostimulants, challenging traditional regulatory classifications and emphasizing their essential role in sustainable agronomy, growing phyconomy, and global food security.