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This article in AJ

  1. Vol. 84 No. 3, p. 409-414
    Received: July 1, 1991

    * Corresponding author(s):
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Agronomic Characteristics That Identify High Yield, High Protein Soybean Genotypes

  1. John Imsande 
  1. Dep. of Agronomy, Iowa State Univ., Ames, IA 50011



Seed yield and seed protein content are both heritable traits; however, breeding trials frequently reveal a negative correlation between the two traits. The objectives of this study were to measure and calculate various N-dependent growth characteristics of soybean [Glycine max (L.) Merr.] and to determine their relation to seed yield and seed protein. Well-nodulated plants, each fixing approximately 180 mg N during pod fill, were grown hydroponically in a growth chamber with or without NO3−N during pod filling. Twenty growth-yield characteristics, including yield, harvest index, N harvest index, and Kjeldahl analysis of N2 fixation, were measured or calculated for each of the 384 plants examined. The highest seed yields, approximately 10 g plant−1, and the highest seed N contents, approximately 560 mg plant−1, were obtained when well-nodulated plants were provided some fertilizer-N during pod fill. Except for N content (%) of the dried plant, correlations between each pair of the 20 N-dependent growth-yield characteristics were generally positive. In the absence of fertilizer-N during pod fill, however, N content (%) of the seeds did not correlate with either harvest index or N harvest index, suggesting that insufficient N during pod fill interferes with the orderly mobilization of foliar-N to the developing seeds. New physiological parameters (seed yield merit, N yield merit, and merit of genotype) are proposed for the identification of genetic lines that produce both a high seed yield and a high seed protein content.

Journal paper no. J-13998 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, Project 2888.

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