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This article in AJ

  1. Vol. 105 No. 6, p. 1839-1846
    Received: May 27, 2013
    Published: October 4, 2013

    * Corresponding author(s): zhuyq@igssnr.ac.cn
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A New Method for Winter Wheat Critical Nitrogen Curve Determination

  1. Pengfei Chen and
  2. Yunqiang Zhu *
  1. Institute of Geographic Sciences and Natural Resources Research, CAS, Datun road A11, Chaoyang district, Beijing 100101, China


As a plant-based N diagnostic tool, critical N curves can be used to adjust the N input in a field according to the crop demand. Because the existing critical N curve determination methods may overestimate the critical N point, making the designed N curve above the actual one, this study presents an improved method to overcome this drawback. An N experiment was conducted during 2 yr (2010–2012) using different winter wheat (Triticum aestivum L.) cultivars in the northwestern plain of Shandong Province, China. Shoot biomass and N concentration were sampled weekly during the growing season. A new method for designing critical N curves was developed based on the existing N curve determination method and the t-test inversion. Using the above data set, the new and existing methods for designing a critical N curve were compared, and the effects of the different cultivars on the proposed N curve were evaluated. The results showed that the critical N curves generated using existing methods can successfully classify N-limited plants but fail to classify non-N-limited plants, however, the critical N curve determined using the new method was able to classify both N-limited and non-N-limited plants satisfactorily. Cross-validation showed that the new method exhibited a highest total correct classification rate of 76%, while the existing methods displayed total correct classification rates below 64%. Additionally, the proposed critical N curve is robust within species within the same region. Thus, the new method may be useful for N management in the field.

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Copyright © 2013. Copyright © 2013 by the American Society of Agronomy, Inc.