Impact of bacterial inoculations on Pisum sativum L. biometric parameters and associated bacterial and AM fungal communities under semi-arid field conditions in Tunisia

In Mediterranean agroecosystems, pea (Pisum sativum L.) is one important crop due to its nutritional benefits and high protein content. However, soil nutrient availability and soil health are known to affect pea productivity, especially under arid and semi-arid conditions. Currently, the use of plant growth-promoting bacteria (PGPB) may represent a bio-based tool to improve pea productivity in drought-affected areas. Nevertheless, there is limited knowledge on how PGPB inoculations in field could impact native communities of bacteria and arbuscular mycorrhizal fungi (AMF) in these areas. Here, a two-year field study in Tunisia was established to evaluate the effects of inoculating two pea varieties with three strains of potential PGPB, including Rhizobium laguerreae and two strains of Erwinia sp., on agronomic performance and soil microbial communities. Inoculations improved productivity and all measured biometric parameters, with the treatment including a consortia of the three strains showing the highest benefits. Metabarcoding analysis showed an increased bacterial and AM fungal diversity in soil of inoculated plants. Additionally, specific AMF-bacterial associations were identified, suggesting a synergistic role in enhancing soil health and pea growth. Overall, this study highlights the potential of targeted bacterial inoculations to improve pea performance under semi-arid environments by exploiting beneficial plant-microbe interactions. These results support the use of microbial inoculants as a sustainable agricultural practice in semi-arid areas, also improving the understanding of their impact on native bacterial and AM fungal communities.