title: Image-based 3D canopy reconstruction to determine potential productivity in complex multi-species crop systems.
abstract: Intercropping systems contain two or more species simultaneously in close proximity. Due to contrasting features of the component crops, quantification of the light environment and photosynthetic productivity is extremely difficult. However it is an essential component of productivity. Here, a low-tech but high-resolution method is presented that can be applied to single- and multi-species cropping systems to facilitate characterization of the light environment. Different row layouts of an intercrop consisting of Bambara groundnut ( Vigna subterranea ) and proso millet ( Panicum miliaceum ) have been used as an example and the new opportunities presented by this approach have been analysed.
  
  
  
  Three-dimensional plant reconstruction, based on stereo cameras, combined with ray tracing was implemented to explore the light environment within the Bambara groundnut-proso millet intercropping system and associated monocrops. Gas exchange data were used to predict the total carbon gain of each component crop.
  
  
  
  The shading influence of the tall proso millet on the shorter Bambara groundnut results in a reduction in total canopy light interception and carbon gain. However, the increased leaf area index (LAI) of proso millet, higher photosynthetic potential due to the C4 pathway and sub-optimal photosynthetic acclimation of Bambara groundnut to shade means that increasing the number of rows of millet will lead to greater light interception and carbon gain per unit ground area, despite Bambara groundnut intercepting more light per unit leaf area.
  
  
  
  Three-dimensional reconstruction combined with ray tracing provides a novel, accurate method of exploring the light environment within an intercrop that does not require difficult measurements of light interception and data-intensive manual reconstruction, especially for such systems with inherently high spatial possibilities. It provides new opportunities for calculating potential productivity within multi-species cropping systems, enables the quantification of dynamic physiological differences between crops grown as monoculture and those within intercrops, and enables the prediction of new productive combinations of previously untested crops.
authors.affiliation: Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK.|Crops For the Future, Jalan Broga, 43500 Semenyih Selangor Darul Ehsan, Malaysia.
authors.forename: Alexandra J
authors.initials: AJ
authors.lastname: Burgess
authors.affiliation: Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK.|School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Renata
authors.initials: R
authors.lastname: Retkute
authors.affiliation: School of Computer Science, University of Nottingham, Jubilee Campus, Wollaton Road, Nottingham NG8 1BB, UK.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Pound
authors.affiliation: Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK.|Crops For the Future, Jalan Broga, 43500 Semenyih Selangor Darul Ehsan, Malaysia.
authors.forename: Sean
authors.initials: S
authors.lastname: Mayes
authors.affiliation: Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK.
authors.forename: Erik H
authors.initials: EH
authors.lastname: Murchie
mesh_terms: D000069599:Crop Production / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008027:Light; D008962:Models, Theoretical; D008897:Panicum / Q000254:growth & development; D010788:Photosynthesis; D000070658:Vigna / Q000254:growth & development
keywords: 3D reconstruction; Bambara groundnut (Vigna subterranea (L.) Verdc.); canopy architecture; canopy productivity; intercropping; light interception; photosynthesis; proso millet (Panicum miliaceum); ray tracing