Overcoming seed dormancy in Parthenium hysterophorus: Seasonal dynamics and standardized approaches for synchronized germination

Parthenium hysterophorus is a highly invasive weed species that exhibits remarkable adaptability to abiotic stresses, including drought, salinity, and temperature extremes. However, strong and season-dependent seed dormancy restricts uniform and synchronized germination under controlled conditions, posing a major limitation for reproducible laboratory experiments. Developing reliable approaches to overcome this dormancy is therefore essential for generating uniform plant material for physiological and molecular studies. In this study, we evaluated the influence of seasonal seed collection (summer and winter), storage duration, and multiple dormancy-breaking approaches, including water immersion, cold stratification, gibberellic acid (GA₃) treatment, and polyethylene glycol (PEG) priming, to identify effective strategies for improving seed germination in P. hysterophorus. Freshly harvested winter-collected seeds showed high and relatively uniform germination following the standard heat treatment protocol, whereas summer-collected seeds showed markedly lower germination. Storage at room temperature markedly reduced germination in both seasonal seed lots. Water immersion substantially improved germination in dormant seed lots. Among the additional dormancy-breaking treatments evaluated, GA₃ significantly enhanced germination and seedling vigour, with 20, 200 and 500 ppm producing the highest germination responses, while PEG priming showed only moderate, concentration-dependent effects. Independently, cold stratification effectively alleviated dormancy and promoted rapid, synchronized, and healthy seedling establishment under controlled laboratory conditions. The optimized dormancy-breaking approaches generated more uniform germination and seedling establishment across the dormant seed lots tested. These results provide practical approaches for obtaining more uniform P. hysterophorus seedlings, facilitating reproducible studies on weed biology, stress physiology, and weed management-related research.