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This article in CS

  1. Vol. 49 No. 1, p. 299-312
    Received: Mar 17, 2008

    * Corresponding author(s): g.hammer@uq.edu.au
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Can Changes in Canopy and/or Root System Architecture Explain Historical Maize Yield Trends in the U.S. Corn Belt?

  1. Graeme L. Hammer *a,
  2. Zhanshan Dongb,
  3. Greg McLeanc,
  4. Al Dohertyc,
  5. Carlos Messinab,
  6. Jeff Schusslerb,
  7. Chris Zinselmeierbd,
  8. Steve Paszkiewiczb and
  9. Mark Cooperb
  1. a The University of Queensland, School of Land, Crop, and Food Sciences, Agricultural Production Systems Research Unit (APSRU), Brisbane, QLD 4072, Australia
    b Pioneer Hi-Bred International, Johnston, IA 50131-0552
    c Dep. of Primary Industries and Fisheries, APSRU, Toowoomba, QLD 4350, Australia
    d current address: Syngenta, Slater, IA 50244


Continuous increase in the yield of maize (Zea mays L.) in the U.S. Corn Belt has involved an interaction with plant density. A number of contributing traits and mechanisms have been suggested. In this study we used a modeling approach to examine whether changes in canopy and/or root system architecture might explain the observed trends. A maize crop model was generalized so that changes in canopy and root system architecture could be examined. A layered, diurnal canopy photosynthesis model was introduced to predict consequences of change in canopy architecture. A two-dimensional root exploration model was introduced to predict consequences of change in root system architecture. Field experiments were conducted to derive model parameters for the base hybrid (Pioneer 3394). Simulation studies for various canopy and root system architectures were undertaken for a range of sites, soils, and densities. Simulated responses to density compared well with those found in field experiments. The analysis indicated that (i) change in root system architecture and water capture had a direct effect on biomass accumulation and historical yield trends; and (ii) change in canopy architecture had little direct effect but likely had important indirect effects via leaf area retention and partitioning of carbohydrate to the ear. The study provided plausible explanations and identified testable hypotheses for future research and crop improvement effort.

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