Comparative efficacy of conventional and nano-formulations of silica and chitosan against Fusarium oxysporum causing wilt in pea (Pisum sativum).

backgroundVascular wilt caused by F. oxysporum f. sp. pisi is among the most destructive soil-borne diseases threatening pea cultivation worldwide, particularly under warm and humid conditions that favor pathogen proliferation. Conventional management strategies rely heavily on chemical fungicides; however, their extensive use has resulted in environmental contamination, health concerns, and the emergence of resistant pathogen strains. Recently, nanotechnology-based disease management has emerged as a sustainable alternative. Silicon (Si) and chitosan (Cs) are recognized as effective resistance inducers, and their nano-formulations (Si-NPs and Cs-NPs) may further enhance disease suppression and activation of plant defense responses. An integrated strategy combining in vitro antifungal assays, greenhouse disease evaluation, and multi-level physiological and anatomical analyses was employed. Nevertheless, comparative evaluations of these nano-elicitors against F. oxysporum in pea remain limited, particularly under greenhouse conditions.

resultsIn vitro assays demonstrated that Si-NPs and Cs-NPs completely inhibited mycelial growth (100% inhibition) of F. oxysporum f. sp. pisi at 150 µg/mL, whereas conventional Si (8 g/L) achieved only 50.7% inhibition, and Cs (8 g/L) achieved 100% inhibition. Under greenhouse conditions, seed treatment with Si-NPs markedly reduced the severity of Fusarium wilt in pea plants by 72.7%, showing a level of protection comparable to the systemic fungicide control. Likewise, Cs-NPs significantly decreased wilt severity by 72.2%, whereas conventional Si and Cs treatments were less effective, achieving 60.6% and 63.6% reductions, respectively. Biochemical analyses showed that Si-NPs increased total phenols by 116.8%, polyphenol oxidase (PPO) by 102%, and peroxidase (POD) by 31.4%, followed by Cs-NPs (106.6%, 72.1%, and 27.9%, respectively). Si-NPs also enhanced chlorophyll a, b, total chlorophyll, and carotenoids by 108.9%, 43.7%, 111.7%, and 69.2%, while reducing membrane permeability and lipid peroxidation by 37.1% and 69.8%, respectively. Si-NPs increased total root section thickness, cortex thickness, vascular cylinder thickness, and xylem vessel diameter by 15.81%, 12.51%, 21.00%, and 90.60%, respectively, while Cs-NPs enhanced these traits by 13.73%, 7.85%, 19.02%, and 63.76%. Notably, nano-formulations-particularly Si-NPs-promoted coordinated reinforcement of root tissues, reflected by optimized cortex-to-vascular cylinder ratios, which likely contributed to enhanced resistance against F. oxysporum without impairing vascular function.

conclusionsThe findings of this study demonstrate that Si-NPs and Cs-NPs provide superior protection against F. oxysporum-induced wilt in pea plants compared to their conventional counterparts. Their enhanced performance is attributed to a dual mode of action-direct antifungal activity and the stimulation of plant defense responses. These results underscore the potential of Si-NPs and Cs-NPs as promising, eco-sustainable alternatives to synthetic fungicides for integrated disease management in legumes. Future studies should focus on evaluating their long-term field efficacy, formulation stability, and environmental safety to facilitate large-scale agricultural applications.