Sustainable management of Zea mays Fusarium Wilt through antioxidant-rich Sargassum aquifolium aqueous extract

Abstract

Fusarium wilt, caused by Fusarium oxysporum, is a soil-borne disease that significantly reduces crop productivity and causes economic losses. Conventional management relies heavily on chemical fungicides, which raise environmental and health concerns and contribute to pathogen resistance. Despite increasing interest in natural bioagents, the potential of marine algal extracts, particularly Sargassum aquifolium, for managing Fusarium wilt in maize (Zea mays L.) remains insufficiently explored. Therefore, this study aimed to evaluate the efficacy of S. aquifolium aqueous extract (SAE) as a sustainable biocontrol agent against Fusarium wilt. Qualitative phytochemical screening of SAE revealed the presence of phenols, tannins, reducing sugars, coumarins, flavonoids, and saponins. High-performance liquid chromatography (HPLC) analysis identified several phenolic compounds, with gallic acid (42.9 µg/g), hesperetin (26.1 µg/g), and caffeic acid (2.2 µg/g) being the most abundant. SAE also exhibited strong antioxidant activity and high DPPH radical scavenging capacity. In vitro antifungal assays demonstrated that the application of 2000 µL of SAE crude extract (0.333 g/mL) showed the moderate inhibitory effect against F. oxysporum isolate R3SH PQ636986, achieving 40.9% growth inhibition. In vivo pot experiments further confirmed the protective role of SAE, where disease index was significantly (ANOVA p < 0.05) reduced from 61.6% to 26.6%, and plant protection efficiency increased by 56.8%. Infection with F. oxysporum caused notable declines in fresh and dry biomass, shoot and root lengths, photosynthetic pigments, and protein content of maize plants, accompanied by elevated oxidative stress markers, including malondialdehyde (MDA; 36.8% increase) and hydrogen peroxide (H2O2; 16.5% increase). However, SAE application markedly improved vegetative growth, photosynthetic pigments, and osmoregulatory compounds such as proline, glycine betaine, and phenolics. Additionally, SAE reduced MDA (10.7% decrease) and H2O2 (8.5% decrease) levels and enhanced antioxidant activity, contributing to increased plant tolerance against Fusarium infection. In conclusion, SAE acts as both a biocontrol agent and a biostimulant, effectively enhancing maize tolerance to Fusarium wilt. These findings highlight its potential as an eco-friendly and sustainable alternative to chemical fungicides for integrated disease management strategies.