ANTIFUNGAL POTENTIAL OF HALODULE UNINERVIS SEAGRASS EXTRACTS AGAINST SUGARCANE-ASSOCIATED FUSARIUM PATHOGENS

Abstract

Sugarcane cultivation is adversely affected by fungal diseases, resulting in substantial losses in crop yield and quality and increasing reliance on chemical fungicides. The present study investigated the antifungal potential of the marine seagrass Halodule uninervis against fungal pathogens associated with sugarcane diseases. Diseased sugarcane samples were collected from Erode, Salem, and Tiruvannamalai districts of Tamil Nadu, India. Fungal pathogens were isolated on Potato Dextrose Agar and identified based on their cultural and microscopic characteristics as Fusarium oxysporum, Fusarium sacchari, and Fusarium incarnatum. The collected H. uninervis biomass was shade-dried, powdered, and extracted using aqueous and acetone-based extraction methods. Qualitative phytochemical analysis revealed the presence of phenols, tannins, flavonoids, proteins, and alkaloids in both extracts, whereas glycosides, terpenoids, and steroids were detected exclusively in the acetone extract. Based on the phytochemical profile, the acetone extract was further evaluated for antifungal activity using the agar well diffusion assay at concentrations of 10, 20, and 50 µL. The extract exhibited concentration-dependent inhibitory activity against all three Fusarium isolates. The highest inhibition zone of 20 mm was observed against F. oxysporum at 50 µL, followed by 14 mm against F. sacchari and 13 mm against F. incarnatum. These results demonstrate that H. uninervis possesses bioactive constituents with promising antifungal properties against important sugarcane-associated Fusarium pathogens. The findings highlight the potential of seagrass-derived bioactive compounds as a natural and environmentally compatible resource for developing sustainable approaches to fungal disease management in sugarcane. Further investigations involving compound identification, mechanism-of-action studies, and in planta and field-level validation are necessary to establish their practical efficacy and application potential.