Microalgae and Cyanobacteria and Their Application in Agriculture: Natural‐Based Biofertilizers, Biostimulants and Biocontrol Compounds

The extensive utilization of chemicals in agriculture over the years, particularly those derived from chemical fertilization, has resulted in the proliferation of both natural and human-induced problems. Consequently, there is an urgent need to explore alternative, viable, and environmentally sustainable solutions. In this regard, microalgae and cyanobacteria, as photosynthetic microorganisms, have been postulated as feasible candidates for this purpose. This is primarily due to their ability to capture CO2 from the environment, as well as micro- and macro-elements. Additionally, their extensive metabolic plasticity enables them to produce a multitude of high-added-value compounds, including biostimulant molecules, biocontrol molecules, and biofertilizer capacity due to their nutrient content. Furthermore, it has been demonstrated that certain species possess the capacity to fix atmospheric nitrogen, a property that confers upon them significant agronomic relevance. This review aims to summarize the potential of these microorganisms and their application in this sector, focusing primarily on their biofertilization, biostimulation, and biocontrol capabilities and presents a compilation of the products currently available on the market that are derived from these microorganisms. The present work also identifies the gaps in the use of these microorganisms and provides future prospects for developing a suitable solution for today's agriculture.