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Agronomy Journal Abstract - SOYBEAN

Differential Response of Soybean Yield Components to the Timing of Light Enrichment


This article in AJ

  1. Vol. 92 No. 6, p. 1156-1161
    Received: Oct 29, 1999

    * Corresponding author(s): sherbert@pssci.umass.edu
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  1. Jomol P. Mathew,
  2. Stephen J. Herbert *,
  3. Shuhuan Zhang,
  4. Andreas A. F. Rautenkranz and
  5. Gerald V. Litchfield
  1. Department of Plant and Soil Science, Bowditch Hall, Univ. of Massachusetts, Amherst, MA 01003 USA


Solar radiation is an important environmental factor influencing seed yield in soybean [Glycine max (L). Merr.]. Our objective was to analyze the response of soybean seed yield components to light enrichment initiated at different growth stages. Light enrichment was imposed on the indeterminate soybean cultivars Altona and Evans by installing wire mesh fencing on either side of the center row to push the adjacent rows aside at different growth stages. Fences prevented plants in the neighboring rows from encroaching on the growing space of the center row plants. Pod number per plant and to a lesser extent seed size accounted for variation in seed yield. Light enrichment initiated at late vegetative or early flowering stages increased seed yield 144 to 252%, mainly by increasing pod number, while light enrichment beginning at early pod formation increased seed size 8 to 23%, resulting in a 32 to 115% increase in seed yield. Responses to light enrichment occurred proportionately across all node positions despite the differences in the time (15–20 d) of development of yield components at the different node positions. Although maximum seed size may be under genetic control in soybean plants, our results suggested seed size can still be modified by the environment with some internal control moderating the final size of most seeds in all pods. It indicates that plants are able to redistribute the available resources to components not yet determined, in an attempt to maintain or improve yield.

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