Antagonistic and Plant Growth-Promoting Potential of Endophytic Trichoderma Against Fusarium Root Rot in Loquat (Eriobotrya japonica)
Loquat (Eriobotrya japonica) is highly susceptible to destructive soil-borne Fusarium pathogens, which cause severe vascular wilt and root rot. While Trichoderma species are widely applied as biocontrol agents, the potential of endophytic Trichoderma strains from loquat remains largely unexplored. This study aimed to isolate and evaluate loquat endophytic Trichoderma strains for their antifungal and plant growth-promoting capabilities. Ten isolates were identified through morphological and phylogenetic analyses as belonging to T. asperellum, T. virens and T. hamatum. Antagonistic activity was initially screened in vitro via dual-culture assays, followed by in vivo greenhouse pot experiments. In vitro results revealed that T. asperellum strains (B077R1 and B077B3) and T. virens GFR9 strongly inhibited the mycelial growth of both F. oxysporum and F. solani (inhibition rates > 50.65%), whereas T. hamatum isolates exhibited weaker antagonism (<35.18%). Moreover, T. asperellum B077R1 demonstrated the highest biocontrol efficacy in the greenhouse pot assay, significantly reducing disease severity caused by F. oxysporum and F. solani by 45.99% and 55.50%, respectively. This strain also significantly enhanced plant height, total biomass (fresh and dry weight) and photosynthetic pigment content (p < 0.05). These findings suggest that newly isolated endophytic Trichoderma strains from loquat exhibit robust host compatibility, offering a promising sustainable strategy for managing root rot in perennial fruit crops.