Document Type

Article

Publication Date

11-2009

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.

Publication Title

Agronomy Journal

Volume

101

Issue

6

First Page

1522

Last Page

1529

Format

application/pdf

Language

en

DOI of Published Version

10.2134/agronj2008.0213x

Publisher

American Society of Agronomy

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S.

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