Biowastes for Plant Production : a guide to plant biostimulants

Sammanfattning: Biostimulants are a suggested tool to achieve sustainable plant production. These are products sourced from biological processes or extracted from biological material, which induces physiological responses in plants. Leading to one or several of the following improvements; better nutrient use efficiency, tolerance to abiotic stress, quality traits or increase the availability of confined nutrients in soil or rhizosphere. This literature review aim to give examples of biological wastes which can be utilized as biostimulants in plant production along with an overview of plant responses. Resulting in a guide which can serve to widen the knowledge about biostimulants and biological wastes which can be relevant for growers, municipalities, industries and horticultural students who wants to explore renewable, circular and biological inputs for plant production. Particularly three biological wastes or by-products are given as examples namely; seaweeds, fish waste and a process called vermicomposting. Sweden aims to become a leading producer of sustainable “Blue food”, meaning increased economic support for businesses working with fish- and seaweed production, it so happens to be that both of these and their by-products have value as biostimulants. They are even two of the most researched by-products for biostimulants globally, known for their multitude of bioactive compounds that can improve plant growth and quality. Which can lead to increased yields while giving the ability to reduce inputs of mineral fertilizer. The third example, vermicomposting, is rather a process that can generate biostimulants by utilizing numerous different kinds of wastes. Conclusion is that biostimulants sourced from biowastes is heterogenous and show wide variation in the nutrient composition and the amount and type of bioactive substances. These bioactive substances are most likely responsible for the beneficial effects on plants and can improve nutrient uptake and nutrient bioavailability, increase overall plant fitness and plant’s tolerance to stresses. Because biostimulants are applied in low concentrations they are, by definition, not considered having enough mineral nutrients that is required by plants. In the future, applying a mixed pool of biostimulants may be a way to deliver both the required nutrients and necessary bioactive substances for optimal plant productivity, this will however require more research and analytical tools. For now biostimulants are at least considered safe for humans, animal and environment.