Microbial inoculants drive disease suppression and rhizosphere modulation for effective management of pepper phytophthora blight

Abstract

Peppers (Capsicum annuum L.) are globally important vegetable crops, yet their production is often compromised by diseases like pepper Phytophthora blight (PPB). Microbial inoculants offer a promising strategy to enhance plant growth and prevent pathogen invasion by establishing diverse core microbial communities in the rhizosphere. This study investigated the efficacy of microbial inoculants, particularly Bacillus subtilis and Trichoderma harzianum, in controlling PPB and enhancing pepper growth under both greenhouse and field conditions. Both individual and combined applications of B. subtilis and T. harzianum significantly suppressed PPB and improved pepper yield. Furthermore, we assessed how these inoculants influenced soil microbial diversity and community structure, identifying key components of the soil microbiome that contribute to disease suppression. The observed suppression of pathogens and promotion of growth were primarily associated with the recruitment of beneficial microbial groups, such as Agromyces, Nocardiopsis, MND1, Gaiella, Iamia, Massilia, Micromonospora, Fusarium, Gibberella, and Gibellulopsis. These findings suggest that microbial inoculants, particularly in combination, can effectively manage PPB and enhance crop productivity through modulation of the rhizosphere microbiome. This study provides valuable insights into the application of microbial inoculants for sustainable pepper production and disease management.