Does induced resistance in plants affect the belowground community?

Abstract

Induced resistance (IR) is a new technology for crop protection that is assumed to be much more environmentally sound than traditional pesticides. The aim of the study presented here was to quantify potential unintended side effects of IR on ecosystem functioning by changes in the composition and performance of the soil community. Resistance was induced by applying the plant activator BION ® to barley and fallow plots. Soil biota were studied by measuring a broad range of microbiological and zoological parameters. The comparative approach used in our study shows that land-use type-specific differences in the effect of BION ® treatment are mediated by plant-specific responses to IR. BION ® treatment significantly reduced the growth of barley roots and increased root infection by the parasitic nematode Pratylenchus, but did not cause measurable changes in plant productivity, in the composition of the free-living soil biota or in root infection by mycorrhizal fungi. In the short term, therefore, we do not expect adverse effects of BION ® treatment on ecosystem functioning via changes in the belowground community. The response patterns revealed in our study might nevertheless help to explain the variability in the effectiveness of IR. Strong reduction of root biomass and selective effects on root-associated soil biota might have long-term effects on ecosystem functioning.