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  1. Vol. 43 No. 4, p. 1367-1374
     
    Received: Apr 22, 2002
    Published: July, 2003


    * Corresponding author(s): PBell@lsu.edu
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doi:10.2135/cropsci2003.1367

Relationships between Leaf-Blade Nitrogen and Relative Seedcotton Yields

  1. Paul F. Bell *a,
  2. D. J. Boquetb,
  3. E. Millhollonc,
  4. S. Moored,
  5. W. Ebelhare,
  6. C. C. Mitchellf,
  7. J. Varcog,
  8. E. R. Funderburgh,
  9. C. Kennedya,
  10. G. A. Breitenbecka,
  11. C. Craiga,
  12. M. Holmani,
  13. W. Bakerj and
  14. J. S. McConnellk
  1. a Agronomy Dep., LSU AgCenter, Baton Rouge, LA 70803-2110
    b Northeast Res. Stn. at St. Joseph and Winnsboro, LA, LSU AgCenter
    c Red River Res. Stn., Bossier City, LA, LSU AgCenter
    d Dean Lee Res. Stn., Alexandria, LA, LSU AgCenter
    e MSU, Mississippi Agric. and Forestry Exp. Stn., Delta Research and Extension Center, Stoneville, MS
    f Dep. Agronomy and Soils, Auburn Univ., Auburn University, AL
    g Dep. Plant Soil Sciences, Mississippi State Univ., Mississippi State, MS
    h Noble Foundation, Ardmore, OK
    i Consultant and formerly of LSU AgCenter
    j Agriculture Studies, Arkansas State Univ., State University, AR
    k Univ. Arkansas–Southeast Res. Ext. Ctr, Monticello, AR

Abstract

Nitrogen fertilization is a required production practice for cotton (Gossypium hirsutum L.) with risks arising from under- and over-fertilization. Tissue testing for diagnosing N deficiencies in crops can use leaf blades and the total N concentration, but this practice has not been rigorously examined in cotton. The primary objective of these experiments was to determine the leaf-N concentration of the uppermost, fully mature leaf blade below which yield loss could be expected. Nitrogen-rate field experiments were conducted at 12 research station and farm sites in the Midsouth USA in Louisiana, Arkansas, Mississippi, and Alabama in 1996 and 1997. Leaf-blade total N concentrations associated with yield loss were 4.3% N at early bloom (R 2 = 0.50) and 4.1% N at mid-bloom (3 wk after early bloom, R 2 = 0.32). The likelihood of applying N when not needed could be reduced by lowering the early bloom critical value to 3.9%. Only 4% of all samples sufficient in N would have been incorrectly diagnosed N deficient at that critical value, but 44% of all deficient samples would have been misidentified as N sufficient. Reduced yields due to over application of N were evident in some samples with leaf N between 4.6 and 4.8% at early bloom. These concentrations were also common for N-sufficient plants, making accurate diagnoses of the over application of N unlikely. Our leaf-N critical values probably differ from previously established values because earlier values were derived via survey techniques and because faster fruiting cultivars may require higher leaf N.

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Copyright © 2003. Crop Science Society of AmericaPublished in Crop Sci.43:1367–1374.