Biostimulants in modern agriculture: a comprehensive review of microbial and non-microbial categories, mechanisms, and sustainability implications

This comprehensive review explores biostimulants, focusing on their categories, benefits, and the rapidly evolving landscape of their use in modern agriculture. The literature search covered publications from 1980 to 2026, with emphasis on recent advances from 2020 to 2026. As pivotal tools, biostimulants enhance plant growth, yield, and stress resistance by stimulating natural physiological processes in plants and soil, providing a sustainable alternative to traditional fertilizers or pesticides. In recent years, the development and adoption of these environmentally friendly materials, often referred to as ‘plant biostimulants,’ have surged. Originating primarily from the organic farming sector, their use has expanded due to rising consumer demand for sustainable practices and growing evidence of their efficacy. This article critically analyzes microbial and non-microbial biostimulants, evaluates their benefits, such as improved nutrient uptake and resilience against abiotic stress, and offers insights into their definition, regulatory framework, and key materials shaping contemporary agriculture. The review synthesizes current knowledge, identifies research gaps, and provides evidence-based recommendations for future research directions.