Long-term Push-pull Cropping System Shifts Rhizosphere and Maize-root Microbiome Diversity Paving Way To Resilient Farming System

Abstract

Background: The rhizosphere biota consists of a complex assembly of microbial communities and other organisms that vary significantly across farming systems and influence soil health and plant productivity. How different cropping systems manipulates soil and plant microbiomes is little understood. In this study, we investigated soil physicochemical properties, rhizosphere and maize-root microbiomes in an agroecological cereal-legume companion cropping system known as push-pull technology (PPT) which has been in use in farmer fields for over two decades for insect-pest management, soil health improvement, and weed control in sub-Saharan Africa. We compared this with the maize-monoculture (Mono) cropping system. Results: PPT cropping system positively impacted the abundance and diversity of soil and maize-root microbial communities and influenced soil physicochemical characteristics compared to Mono. Specific genera of both bacterial and fungal communities drove the variation in diversity of the microbial communities in these cropping systems. Soil and maize-root from the PPT cropping system had enriched Trichoderma, Mortierella, and Bionectria fungal genera while Streptomyces, RB41, and Nitrospira, among other bacterial genera linked to essential ecosystem services like plant protection, decomposition, carbon utilization, production of bioinsecticides, nitrogen fixation, nematode suppression, phytohormone production, and bioremediation. Bacterial from the genus Bryobacter linked to plant pathogenesis was more abundant in Mono-root. Similarly, fungal genera such as Gibberella, Neocosmospora, and Aspergillus, linked to plant pathogenesis and food contamination, were abundant in Mono. Notable differences were observed in the overall diversity of metabiome functional protein pathways, such as syringate degradation, L-methionine biosynthesis I, and inosine 5'-phosphate degradation. Conclusion: Push-pull cropping system improves soil physicochemical properties and shifts soil and maize-root microbiomes in farmer fields in favour of microbial communities involved in important ecological services. The current findings add to the diversification of ecosystem services provided by this cropping system where it is practiced and contributes to the system’s resilience and functional redundancy. Underpinning the mechanism through PPT affects the soil and maize-root microbial communities – whether it is through the influence of plant metabolites from the intercrop root exudates or is the alteration of the soil nutritional status which affects microbial enzymatic activities should be the future focus.