<![CDATA[Background: High-quality seeds are essential for crop establishment, but seed deterioration can reduce seed viability and vigor. Since controlled water uptake is fundamental to seed priming, osmoconditioning with polyethylene glycol (PEG) 6000 has been investigated to regulate seed hydration. Objective: This narrative review aimed to critically synthesize evidence on the physiological mechanisms of osmoconditioning with PEG 6000, its reported effects on seed viability and vigor, factors contributing to variation in seed responses, and current research gaps. Methods: A narrative review supported by a structured literature search was conducted using publications from 2016 to 2026. Evidence was comparatively synthesized according to physiological mechanisms, PEG concentration or osmotic potential, priming duration, plant species, and responses related to seed viability and vigor. Results: Osmoconditioning with PEG 6000 was associated with favorable responses in germination percentage, uniformity, seedling length, and other seed viability and vigor parameters, although responses varied among plant species and treatment conditions. Physiologically, PEG 6000 lowers external water potential, enabling controlled hydration and pre-germinative processes while limiting premature radicle protrusion. Increasing PEG 6000 concentration or extending priming duration did not consistently produce greater improvements, indicating that responses depend on the combination of osmotic conditions, priming duration, and vary among plant species. Conclusion: Osmoconditioning with PEG 6000 has been reported as a promising seed priming strategy, but the evidence does not support a universally optimal treatment protocol. Further research should address plant species and seed specific treatment conditions, post-priming storability, reproducibility across seed lots, field consistency, and underexplored plant species.]]>
