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This article in AJ

  1. Vol. 101 No. 6, p. 1522-1529
     
    Received: Dec 2, 2008
    Published: Nov, 2009


    * Corresponding author(s): sharon.clay@sdstate.edu
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doi:10.2134/agronj2008.0213x

Corn Response to Competition: Growth Alteration vs. Yield Limiting Factors

  1. S. A. Clay *a,
  2. D. E. Claya,
  3. D. P. Horvathb,
  4. J. Pullisc,
  5. C. G. Carlsona,
  6. S. Hansena and
  7. G. Reicksa
  1. a South Dakota State Univ., Plant Science Dep., Brookings, SD 57007
    b USDA-ARS, Biosciences Research Lab., Fargo, ND, 58105
    c Michigan State Univ. Ext., Rogers City, MI. 49779

Abstract

Competition mechanisms among adjacent plants are not well understood. This study compared corn growth and yield responses to water, N, and shade at 74,500 plants ha−1 (1×) with responses to water and N when planted at 149,000 plant ha−1 Plant biomass, leaf area, chlorophyll content, reflectance, and enzyme expression (transcriptome analysis) were measured at V-12. Grain and stover yields were measured with grain analyzed for 13C isotopic discrimination (Δ) and N concentration. At V-12, 60% shade plants had increased chlorophyll and reduced leaf area and height compared to full sun plants. In the 2× treatment, plants had 11% less chlorophyll than 1× plants with leaf area and height similar to 60% shade plants. At harvest, plants in the 2× treatment were smaller, had increased water and N use efficiency, and an 11% per hectare yield increase compared with the 1× unstressed treatment. Per-plant yields from 60% shade and 2× treatments were 50% less than 1× unstressed treatment. Yield reduction in shaded plants was attributed to light stress. Lower yield in the 2× treatment was attributed to a population-density induced 20% decrease in the red/near-infrared (NIR) ratio, which resulted in downregulation of C4 carbon metabolism enzymes (phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, and pyruvate orthophosphate dikinase). Although the net impact of high plant density and shade stress on per-plant yield were similar, the stress compensation mechanisms differed.

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Copyright © 2009. American Society of AgronomyCopyright © 2009 by the American Society of Agronomy