The effectiveness of three Glomus species (G. mosseae, G. intraradices, and G. etunicatum) in the biocontrol of the root and crown rot pathogens Fusarium solani and mixed Fusarium in pepper plants

Abstract

Abstract In this research, the effectiveness of naturally derived arbuscular mycorrhizal fungus (AMF) species, including Glomus mosseae (GM), G. intraradices (GI), and G. etunicatum (GE), and a mycorrhizal mix (MM) comprising these three species was tested on pepper plants inoculated with two isolates of Fusarium solani (48-F. solani and 18-F. solani) and two isolates of mixed Fusarium (50-F. mixture and 147-F. mixture). ANOVA and Tukey’s test revealed that the effects of AMF inoculations on morphological parameters, disease severity, root colonization, and total spore numbers in pathogen-infected plants varied significantly depending on the AMF species and pathogen group. AMF colonization significantly reduced disease severity, with disease inhibition (DI) reaching up to 58%, depending on the specific pathogen. However, there were a few instances where AMF application did not lead to a reduction in disease severity. Single AMF species were more effective in enhancing the growth of pathogen-treated host plants and suppressing disease compared to mixed AMFs. The mixed AMFs were more effective only in balancing pathogen-induced decreases in plant nutrients (Cu, Mg, Zn, P). Among the compared mycorrhizae, G. etunicatum (GE) was the most effective in disease suppression due to its more positive effects on plant root structure. Root colonization rates were generally higher in plants treated with both mycorrhiza and pathogens than in plants treated with mycorrhiza alone. Overall, the curative effects of AMFs on plants following pathogen application varied concurrently with disease severity rates caused primarily by pathogens. AMFs demonstrated greater efficacy in combating 18-F. solani, which causes less severe plant disease. However, the effectiveness of AMFs was lower against 48-F. solani and 147-F. mix., which cause more severe plant disease. This indicates that the efficacy of AMFs varies depending on the specific strain of Fusarium solani, with better results observed against strains that cause less severe plant disease.