Has agricultural intensification impacted maize root traits and rhizosphere interactions related to organic N acquisition?

Authors: SCHMIDT, JENNIFER - University Of California, Davis; Poret-Peterson, Amisha; LOWRY, CAROLYN - Pennsylvania State University; GAUDIN, AMELIE - University Of California, Davis

Submitted to: AoB Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2020
Publication Date: 6/19/2020
Citation: Schmidt, J.E., Poret-Peterson, A.T., Lowry, C.J., Gaudin, A.C. 2020. Has agricultural intensification impacted maize root traits and rhizosphere interactions related to organic N acquisition?. AoB Plants. 12(4). https://doi.org/doi:10.1093/aobpla/plaa026.
DOI: https://doi.org/10.1093/aobpla/plaa026

Interpretive Summary: Plants and their associated microorganisms can be viewed as an ecological unit or holobiont, which can have functional traits that respond to selective pressures. This study uses the holobiont concept to study the effects of agricultural intensification due to increased inorganic nitrogen fertilizer usage on maize and its rhizosphere microbiome. To this end, maize genotypes that were released before (1936, 1939, and 1942) and after (1984, 1994, and 2015) intensification of synthetic fertilizer usage were tested for their ability to acquire nitrogen from organic sources. The response of root morphology, extracellular enzyme activities, nitrogen cycle gene abundances, and organic nitrogen uptake were assessed. It was found that agricultural intensification has not impaired nitrogen acquisition from organic sources by the modern maize and its microbiome.

Technical Abstract: It is increasingly clear that plant hosts and their associated microbiomes express functional traits and respond to selective pressures as an ecological unit, or holobiont. Although the effects of agricultural intensification on maize and its rhizobiome have previously been investigated separately, the holobiont framework may facilitate greater insight into potential coordinated adaptation to the high-synthetic-input breeding environment. We asked whether the introduction of inorganic nitrogen fertilizer has negatively impacted acquisition of N from organic sources by modern maize-microbiome holobionts. Six maize genotypes released pre-fertilizer (1936, 1939, 1942) or post-fertilizer (1984, 1994, 2015), were grown in rhizoboxes containing patches of 15N-labeled clover/vetch residue. N responsiveness, cycling, and acquisition were compared between eras of release.