Rooting for microbes: impact of root architecture on the microbial community and function in top- and subsoil

Background and aims

Climate change and associated weather extremes pose major challenges to agricultural food production, necessitating the development of more resilient agricultural systems. Adapting cropping systems to cope with extreme environmental conditions is a critical challenge. This study investigates the influence of contrasting root system architectures on microbial communities and functions in top- and subsoil.

Methods

A column experiment was performed to investigate the effects of different root architectures, specifically deep (DRS) and shallow (SRS) root systems of wheat (Triticum aestivum L.) on microbial biomass, major microbial groups, and extracellular enzyme activities in soil. We focused on β-glucosidase (BG) activity, which is an indicator for microbial activity, during different plant growth stages, using destructive and non-destructive approaches.

Results

We found that the DRS promoted microbial biomass and enzyme activity in subsoil, while the SRS increased the microbial biomass and enzyme activity in topsoil. In-situ soil zymography provided fine-scale spatial insights, highlighting distinct patterns of BG activity near root centers and formation of enzyme activity hotspots, which were defined as regions where enzyme activity exceeds the mean activity level by 50%. Temporal changes in BG activity further underscored the dynamic nature of root-microbe interactions. Extracellular enzyme activities indicated varying carbon, nitrogen and phosphorus acquisition strategies of rhizosphere microorganisms between top- and subsoil.

Conclusion

This study underscores the need to consider root system architecture in agricultural strategies, as it plays a crucial role in influencing microbial communities and enzyme activities, ultimately affecting carbon and nutrient cycling processes in top- and subsoil.