Plant Growth Regulators (PGRs) are organic compounds that, at very low concentrations, can modify or partially or completely inhibiting the physiological development of plants. Unlike nutrients, these molecules function as chemical messengers that activate or repress specific genes, coordinating processes ranging from seed germination to fruit maturation. Modern biotechnology has established these substances as valuable tools for improving crop productivity and quality by regulating the production of secondary metabolites and optimizing harvest timing.

From a technical standpoint, a plant hormone (phytohormone) is synthesized naturally by the plant, whereas plant growth regulators are synthetic analogues, often exhibiting greater biological activity, that mimic the physiological functions of their corresponding endogenous phytohormones. The effectiveness of these compounds depends on both the application rate and timing, but more importantly on the formulation’s ability to maintain the active molecule in a stable, bioavailable form throughout the application process. The biosynthesis and stability of these hormones are highly sensitive to environmental conditions such as pH and water availability, factors that likewise influence the efficacy of exogenously applied plant growth regulators.