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This article in CS

  1. Vol. 52 No. 3, p. 1281-1289
    Received: Aug 8, 2011

    * Corresponding author(s): lpurcell@uark.edu
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Soybean Nitrogen Fixation and Nitrogen Remobilization during Reproductive Development

  1. Adriano T. Mastrodomenicoa and
  2. Larry C. Purcell *b
  1. a 504, Dr. Antonio Bento Street 133A, Sao Paulo - SP, Brazil, 04750-000
    b Dep. Of Crop, Soil, and Environmental Sciences, Univ. of Arkansas, 1366 W. Altheimer Dr., Fayetteville, AR 72704


Seed N is important for soybean [Glycine max (L.) Merr.] because of the high grain protein concentration. However, the association between N2 fixation and N remobilized from vegetative tissues to seed across different maturity groups (MGs) is not well understood. We hypothesized that increased amounts of biomass at the beginning of seedfill for late-maturing genotypes would provide a larger pool of N that was available for remobilization during seedfill and would increase yield relative to earlier-maturing genotypes. Near isolines for maturity (MG IV, V, and VI), a modern breeding line (R01-416F, MG V), and a non-nodulated soybean genotype (MG VI) were harvested periodically from beginning seedfill to physiological maturity to determine N remobilization and N2 fixation. Nitrogen fixation contributed approximately 90% of the seed N. The MG VI isoline accumulated larger N amounts in vegetative tissues than the MG IV isoline. Maturity isolines had similar seed N content, but the MG IV genotype had higher N harvest index (2009) than the MG VI isoline. In 2009, R01-416F had greater yields and N content than the isolines, but there was no indication that N remobilization during seedfill was greater. These data indicate that N2 fixation continued until late seedfill and supplied nearly all of seed N. A large reservoir of N in the vegetative tissue of late MGs was not fully used, and N was not a limitation to yield under these conditions.

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