title: Simultaneous effects of leaf irradiance and soil moisture on growth and root system architecture of novel wheat genotypes: implications for phenotyping.
abstract: Plants in the field are exposed to varying light and moisture. Agronomic improvement requires knowledge of whole-plant phenotypes expressed in response to simultaneous variation in these essential resources. Most phenotypes, however, have been described from experiments where resources are varied singularly. To test the importance of varying shoot and root resources for phenotyping studies, sister pre-breeding lines of wheat were phenotyped in response to independent or simultaneous exposure to two light levels and soil moisture profiles. The distribution and architecture of the root systems depended strongly on the moisture of the deeper soil layer. For one genotype, roots, specifically lateral roots, were stimulated to grow into moist soil when the upper zone was well-watered and were inhibited by drier deep zones. In contrast, the other genotype showed much less plasticity and responsiveness to upper moist soil, but maintained deeper penetration of roots into the dry layer. The sum of shoot and root responses was greater when treated simultaneously to low light and low soil water, compared to each treatment alone, suggesting the value of whole plant phenotyping in response to multiple conditions for agronomic improvement. The results suggest that canopy management for increased irradiation of leaves would encourage root growth into deeper drier soil, and that genetic variation within closely related breeding lines may exist to favour surface root growth in response to irrigation or in-season rainfall.
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany k.nagel@fz-juelich.de.
authors.forename: Kerstin A
authors.initials: KA
authors.lastname: Nagel
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia Present address: Bayer Crop Science, 90th Street S, Sabin, MN 56580, USA.
authors.forename: David
authors.initials: D
authors.lastname: Bonnett
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia Present address: ANU College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Furbank
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany Present address: Institute of Agricultural Sciences, Swiss Federal Institute of Technology Zurich (ETHZ), Universitätstrasse 2, 8092 Zürich, Switzerland.
authors.forename: Achim
authors.initials: A
authors.lastname: Walter
authors.affiliation: Institute of Bio- and Geosciences, IBG-2: Plant Sciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schurr
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Watt
mesh_terms: D008027:Light; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D014908:Triticum / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: Light; root branching; root depth; root partitioning; water deficit; water uptake.