Reducing fertiliser inputs: plant biostimulants as an emerging strategy to improve nutrient use efficiency

Innovations in agriculture, including application of chemical fertilisers, have allowed food production to keep pace with the growing population. Nevertheless, this has come at a significant environmental cost. Improving plant nutrient use efficiency (NUE) is critical in tackling greenhouse gas emissions, improving biodiversity and increasing productivity in agricultural systems to meet the requirements of the growing world population. Biostimulants are compounds from various sources that can regulate plant physiological processes and increase nutrient uptake and utilisation. Consequently, integrating use of plant biostimulants with conventional agriculture may facilitate reduced fertiliser use while maintaining crop yields. Here, we discuss the current research on biostimulants in the context of improved macro- and micronutrients use efficiency. While most of the reviewed studies report a positive effect of biostimulants on NUE within the studied crop, there is a need for a more systematic approach, including precise calculations of NUE and conducting trials under both optimum and sub-optimum nutrient conditions. Overall, plant biostimulants appear to be a promising addition to sustainable agriculture practices, with multiple benefits from both social and environmental perspectives.