Effect of Hydrogen Peroxide Treatments on Seed-borne Fungal Pathogens, Germination, and Seedling Vigor in Papaya (Carica papaya L.)

Abstract

Background and Objective: Seed-borne fungal pathogens pose a significant threat to papaya (Carica papaya L.) seed quality and seedling vigor, ultimately affecting crop establishment and productivity. This study aimed to identify seed-borne fungal contaminants in papaya seeds from different sources and evaluate the effectiveness of hydrogen peroxide (H₂O₂) treatments in managing these pathogens while enhancing seed germination, vigor, and reducing seedling mortality. Materials and Methods: The experiment was conducted from January to June 2024 at the Department of Plant Pathology, Patuakhali Science and Technology University (PSTU), Bangladesh, using a Completely Randomized Design (CRD) with three replications. Seeds were collected from five sources, including three farmer-stored and two commercial suppliers. Seed-borne fungi were isolated using the ISTA-recommended moist blotter method. Four concentrations of H₂O₂ (0.5%, 1.0%, 2.0%, 3.0%) were tested in vitro against identified fungi using the poisoned food technique. Germination percentage, vigor index, and seedling mortality were recorded to assess the physiological responses of treated seeds. Results: Four fungal species—Aspergillus flavus, Rhizopus stolonifer, Curvularia lunata, and Fusarium moniliforme—were isolated from all seed sources, with the highest prevalence found in farmer-saved seeds. Among the treatments, 3% H₂O₂ showed the strongest antifungal activity, significantly inhibiting mycelial growth of all fungi, especially Rhizopus stolonifer (91.74%). However, 1% H₂O₂ was the most effective in enhancing seed performance, recording the highest germination rate (84.67% at 15 DAS), shoot (2.76 cm) and root length (4.76 cm), and vigor index (636.72). Moreover, it significantly reduced seedling mortality to 2.26%, compared to 7.95% in the untreated control. In contrast, 3% H₂O₂ negatively impacted germination and vigor despite its strong antifungal activity. Conclusion: Hydrogen peroxide at 1% concentration offers an effective and eco-friendly seed treatment strategy for improving papaya seed health and vigor while minimizing seedling mortality. Although higher concentrations exhibit superior antifungal effects, they may impair seed viability. These findings suggest that moderate levels of H₂O₂ can be integrated into seed treatment protocols for papaya to enhance seed quality and reduce fungal infection.