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Agronomy Journal Abstract -

Effect of N Fertilizer on Protein Content of Grain, Straw, and Chaff Tissues in Soft White Winter Wheat1


This article in AJ

  1. Vol. 77 No. 2, p. 229-232
    Received: Apr 2, 1984

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  1. D. M. Glenn,
  2. A. Carey,
  3. F. E. Bolton and
  4. M. Vavra2



Nitrogen management programs of soft white winter wheat (Triticum aestivum L.) in semiarid regions are generally based upon soil tests of available water and residual N levels. The purpose of this work was to develop postharvest criteria for N-sufficiency and N-insufficiency based on tissue protein levels as it relates to maximum grain yield in a fallow-wheat rotation. Yield-protein relationships in grain, straw, and chaff tissues were examined in field trials from 4 harvest years on a Walla Walla silt loam (coarse-silty, mixed, mesic, Typic Haploxeroll). Grain protein content was a better postharvest indicator of N sufficiency for maximum grain yield than straw or chaff protein levels. Excessive weed growth confounded this relationship in 1 year. Using a chi-square interaction procedure, a critical level of 8.8% grain protein was determined necessary for N sufficiency in ‘Stephens’ soft white winter wheat when weed growth was not a management problem. The transition zone between N sufficient and N insufficient responses was between 8.3 and 9.1% grain protein. The amount of relative yield lost to N insufficiency was related to grain protein content. There was a 9.8% yield reduction for each grain protein percentage below 9.1. Critical protein values indicative of N insufficiency could not be determined for straw and chaff tissues. Straw and chaff protein levels greater than 2.6 and 3.5%, respectively, were exclusively associated with N sufficiency.

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