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This article in AJ

  1. Vol. 79 No. 3, p. 419-422
    Received: July 15, 1985

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Nitrogen Fertility and Irrigation Influence on Grain Sorghum Nitrogen Efficiency1

  1. T. R. Zweifel,
  2. J. W. Maranville,
  3. W. M. Ross and
  4. R. B. Clark2



Little of the research concerning efficient use of N by crops has examined genotypic variation for the amount of dry matter produced per unit of N absorbed by a plant. A replicated field experiment was conducted for 2 yr to determine the influence of N fertility and irrigation on the N use efficiency of selected grain sorghum [Sorghum bicolor) L.) Moench] hybrids. Thirty-six F1 hybrids, produced from six female and six male inbreds, were grown under dryland or irrigated conditions with 0 or 112 kg ha−1 N. Samples of the aboveground dry matter were harvested after physiological maturity, separated into leaf, stalk, and grain fractions, and analyzed for reduced N. Hybrid N efficiency was evaluated by ratios of dry weight to plant N content. Significant differences were found among the hybrids and their common parent averages for efficiency ratios, dry weight, and N content. Irrigation had little effect on N utilization efficiency and produced no significant change in the relationship among hybrids for N efficiency. Hybrid N efficiency values were over 30% higher in plots without N fertilizer. Interactions among hybrids and N levels were significant for N efficiency traits and grain weight. Alternate definitions of N efficiency emphasized different characteristics, but the potential for selection of sorghum hybrids with improved efficiency of N use was evident.

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