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This article in SSSAJ

  1. Vol. 65 No. 6, p. 1823-1828
     
    Received: Jan 31, 2001
    Published: Nov, 2001


    * Corresponding author(s): david_clay@sdstate.edu
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doi:10.2136/sssaj2001.1823

Nitrogen and Water Stress Interact to Influence Carbon-13 Discrimination in Wheat

  1. D. E. Clay *a,
  2. R. E. Engelb,
  3. D. S. Longc and
  4. Z. Liua
  1. a Plant, Plant Science Dep., South Dakota State Univ., Brookings, SD 57007
    b Land Resources and Environmental Sciences, Montana State Univ., Bozeman, MT
    c Northern Agricultural Research Center, Montana State Univ., Havre, MT 59501

Abstract

The impact of interactions between water and N stress on 13C isotopic discrimination (Δ) is not well understood. The objective of this study was to determine the impact of N on Δ in wheat (Triticum aestivum L.) grown under low, moderate, and high water stress. In a field study located near Havre, Montana, USA (48° 30′ N lat. and 109° 22′ W long.), wheat grown under three different water stress environments (low, moderate, and high) was fertilized with three different N rates (none, moderate, and high). Each treatment was replicated four times. The grain N fertilizer use efficiency increased as water stress decreased. A differential response of Δ to N was observed. In general, if plants were grown under high water stress and N increased yield, then adding N to N-deficient plants reduced Δ (−0.01‰ for every kg of N added); and if plants were grown under low water stress and N increased yield, then adding N had little or no impact on Δ. The break point between N impacting or not impacting Δ was ∼17.45‰. Under non-N limiting (moderate and high N) conditions the equation relating Δ to yield was, yield (kg ha−1) = −11000 + 884 Δ, r = 0.92**. Wheat grown under N-deficient conditions (0N treatment) did not fit this curve. By accounting for the impact of water and N stress on Δ, this variation could be explained. Results from this study suggest that Δ can be used to characterize N and water stress at different landscape positions in watershed studies.

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Copyright © 2001. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.65:1823–1828.