Bacillus seed coating mitigates early growth reduction in successive winter wheat without altering rhizosphere bacterial and archaeal communities.

The soil legacy of successively grown winter wheat (WW) often leads to lower plant growth and yield. In this study, we assessed the effect of Bacillus pumilus seed inoculation on the early growth of successively grown WW. We conducted an outdoor experiment using newly designed temperature-regulated rhizotrons. WW was grown in soil from two rotational positions, i.e., first WW after oilseed rape (W1) and second WW after oilseed rape (W2), until the end of tillering. We measured several plant and soil biochemical parameters. In addition, amplicons of the 16S rRNA gene were sequenced to account for bacterial and archaeal community shifts in the rhizosphere, and functional genes involved in the nitrogen cycle were quantified to estimate possible changes in N cycling due to B. pumilus inoculation. B. pumilus seed coating significantly compensated for the early growth reduction of W2, and this effect was primarily linked to changes in root plasticity with a higher root length density and a smaller specific root length in inoculated W2 compared with non-inoculated W2. There was a higher LAP activity in the rhizosphere of inoculated W2 plants than in the rhizosphere of non-inoculated W2 plants and this was followed by a reduction in soil NO