Bio-stimulants, comprising a broad spectrum of natural and synthetic bioactive compounds, play a crucial role in enhancing plant growth, productivity, and quality through complex physiological, biochemical, and molecular pathways. In organic farming, which emphasises sustainability and environmentally sound practices, bio-stimulants are increasingly recognised as vital inputs.
This chapter explores the diverse mechanisms by which bio-stimulants improve crop performance in organic systems. It categorises them into humic substances, protein hydrolysates, seaweed extracts, and microbial inoculants, detailing their functions in modulating phytohormones, enhancing nutrient uptake, and stimulating beneficial rhizospheric microbes. The chapter further examines their contribution to nutrient use efficiency by improving the availability and assimilation of essential nutrients, thereby optimising metabolic functions. Their role in conferring abiotic stress tolerance is also addressed, focusing on stress-responsive gene activation, strengthened antioxidant defences, and cellular homeostasis under environmental stress.
Additionally, the influence of bio-stimulants on soil health is considered, particularly their effects on soil structure, microbial diversity, and organic matter turnover. Drawing on recent studies and case examples, this chapter highlights the transformative potential of bio-stimulants in organic agriculture, positioning them as key agents in promoting sustainable intensification and resilience in crop production systems
