Effects of PGPR inoculation on root growth and nitrogen accumulation of common wheat in controlled conditions and in open fields

This study investigated whether a commercial bio-fertiliser containing a consortium of PGPB affects root and shoot growth and N accumulation in common wheat. Trials were conducted firstly in rhizoboxes, applying bacteria either as a seedcoating inoculum or foliar+soil spraying, and then in the field by spraying bacteria to the canopy at tillering stage with decreasing N fertilisation (160, 120, 80 kg ha-1). Environmental scanning electron microscope (ESEM) imaging revealed their excellent ability to colonise plant surface and both leaf mesophyll and root vascular tissues. Bacteria increased the number of root tips and ramifications (+65% vs. noninoculated) in sterilised pot soil and the root length density in the open field with medium (+29%) and high (+11%) N supply, resulting in greater N accumulation (about +25 kg ha-1). Although without yield benefits, the rooting power of these bacteria can help to reduce N losses from agro ecosystems and to save chemical fertilisers.