Seaweeds as Plant Biostimulants
The performance of plants subjected to environmental challenges can be improved by applying seaweed-based products, which are eco-friendly alternatives to the use of fertilizers and synthetic biostimulants. There is also evidence that plant development can be indirectly improved by using seaweed extracts that can mediate, for instance, the legume-rhizobia symbiotic relationship. The high variation in the composition of seaweed extracts and, consequently, their effects is one of the major challenges for the industry of seaweed-based biostimulants. Seaweed extracts can also improve the asexual propagation of plants, as shown by the increased fresh weight of roots and leaves in sweet potato apical cuttings treated with A. nodosum extract, when compared to untreated plants. The effects of the application of seaweed extracts on plant development and yield are diverse and, frequently, contradictory, possibly because of their dependence on complex and intricate factors.