Unlocking the potential of biostimulants derived from organic waste and by-product sources: Improving plant growth and tolerance to abiotic stresses in agriculture

Due to population growth and expanding economic activities, waste generation is on the increase globally. Reuse of waste or by-products in agriculture as biostimulants and fertilizers contributes to a circular economy. In recent years, there has been an increasing number of studies on organic waste-derived biostimulants and the economic market for these products is expanding. Many studies have addressed the development of biostimulants from various organic wastes or byproducts. It is worth noting that different types of organic wastes or by-products exhibit different compositions and key mechanisms when used as biostimulants, which require analyzing the mechanism of action from multiple fields such as chemistry and biology. Therefore, this review presents recent advances with respect to organic waste-derived biostimulants. Specifically, it outlines the characteristics of biostimulants derived from different waste or by-products and extraction techniques. The role of organic-waste derived biostimulants in maintaining plant growth and development is described, emphasizing their role in helping plants resist several abiotic stresses. Mechanisms by which organic waste-derived biostimulants affect physiological changes in plants are discussed. This review provides the theoretical foundation to enable the efficient waste material and by-products resource utilization and evidences that the development and production of biostimulants from waste and by-products is an environmentally friendly option for waste recycling and for the increase of crop productivity.