Soil rhizobia promote plant yield by increasing tolerance to pests and pathogens under field conditions

Summary

This field experiment demonstrates that nitrogen-fixing rhizobia in soil promote pea yield not only through direct nitrogen provision, but also by reducing susceptibility to pea aphids and an aphid-borne virus (PEMV). Rhizobia inoculation outperformed synthetic nitrogen fertilisation in improving plant tolerance to both pests and pathogens, with benefits to yield substantially mediated through reduced pest and pathogen pressure. The findings indicate that soil microbial communities exert strong cascading effects on aboveground pest and disease dynamics, and that restoration of beneficial soil microbes may offer an alternative or complement to chemical pest management.

UK applicability

These findings are likely applicable to UK legume production (particularly field peas), where pea aphid and PEMV are recognised pests and pathogens. However, the study was conducted under specific field conditions; UK growers would need to validate rhizobia inoculation strategies and their efficacy under cooler, damper climatic conditions and with UK-endemic pest populations.

Key measures

Aphid abundance, PEMV incidence, pea yield, plant growth; structural equation modelling to partition direct and indirect effects of rhizobia versus nitrogen fertiliser

Outcomes reported

The study measured pea aphid (Acyrthosiphon pisum) abundance, pea enation mosaic virus (PEMV) incidence, and pea plant yield across four soil treatments. Effects of rhizobia inoculation on yield were compared to synthetic nitrogen fertilisation and soil sterilisation controls.

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