title: High-resolution quantification of root dynamics in split-nutrient rhizoslides reveals rapid and strong proliferation of maize roots in response to local high nitrogen.
abstract: The plant's root system is highly plastic, and can respond to environmental stimuli such as high nitrogen (N) in patches. A root may respond to an N patch by selective placement of new lateral roots, and therewith increases root N uptake. This may be a desirable trait in breeding programmes, since it decreases NO3(-) leaching and N2O emission. Roots of maize (Zea mays L.) were grown without N in split-nutrient rhizoslides. One side of the slides was exposed to high N after 15 d of root development, and root elongation was measured for another 15 d, described in a time course model and parameterized. The elongation rates of crown axile roots on the N-treated side of the plant followed a logistic increase to a maximum of 5.3cm d(-1); 95% of the maximum were reached within 4 d. At the same time, on the untreated side, axile root elongation dropped linearly to 1.2cm d(-1) within 6.4 d and stayed constant thereafter. Twice as many lateral roots were formed on the crown axis on the N side compared to the untreated side. Most strikingly, the elongation rates of laterals of the N side increased linearly with most of the roots reaching an asymptote ~8 d after start of the N treatment. By contrast, laterals on the side without N did not show any detectable elongation beyond the first day after their emergence. We conclude that split-nutrient rhizoslides have great potential to improve our knowledge about nitrogen responsiveness and selection for contrasting genotypes.
authors.affiliation: Department of Experimental Plant Ecology, Radboud University Nijmegen, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands Crop Science, Swiss Federal Institute of Technology Zurich, Universitätsstrasse 2, 8092 Zurich, Switzerland.
authors.forename: Dina
authors.initials: D
authors.lastname: in 't Zandt
authors.affiliation: Crop Science, Swiss Federal Institute of Technology Zurich, Universitätsstrasse 2, 8092 Zurich, Switzerland.
authors.forename: Chantal
authors.initials: C
authors.lastname: Le Marié
authors.affiliation: Crop Science, Swiss Federal Institute of Technology Zurich, Universitätsstrasse 2, 8092 Zurich, Switzerland.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kirchgessner
authors.affiliation: Department of Experimental Plant Ecology, Radboud University Nijmegen, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Eric J W
authors.initials: EJ
authors.lastname: Visser
authors.affiliation: Crop Science, Swiss Federal Institute of Technology Zurich, Universitätsstrasse 2, 8092 Zurich, Switzerland andreas.hund@usys.ethz.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hund
mesh_terms: D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D009584:Nitrogen
keywords: Corn; foraging; nitrogen; rhizotrons; root growth; split-root.