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This article in AJ

  1. Vol. 97 No. 4, p. 1136-1140
     
    Received: Dec 1, 2004
    Published: July, 2005


    * Corresponding author(s): abruns@ars.usda.gov
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doi:10.2134/agronj2004.0295

Ultra-High Plant Populations and Nitrogen Fertility Effects on Corn in the Mississippi Valley

  1. H. Arnold Bruns * and
  2. H. K. Abbas
  1. USDA-ARS, Crop Genetics and Prod. Res. Unit, Box 345, Stoneville, MS 38776

Abstract

Populations for high yield and low mycotoxin levels in furrow-irrigated corn (Zea mays L.) have yet to be firmly established for the Midsouth USA. Preplant N applications compared with a split application and the effects on yield, yield components, and mycotoxin levels were also examined. Experiments were conducted at Site WR (102-cm-wide rows, Beulah fine sandy loam) and Site NR (76-cm-wide rows, Dundee silty clay). Plant densities of 71760, 82160, 92560, and 102960 plants ha−1 were grown in eight-row plots, 9.1 m long at both sites. The N fertility treatments were 112 kg N ha−1 preplant, 224 kg N ha−1 preplant, and 112 kg N ha−1 preplant + 112 kg N ha−1 sidedressed at V6 (six leaves). Yields at Site WR did not differ among populations. Maximum yields at Site NR were at 71760 plants ha−1 (10.3 Mg ha−1) and then declined (b = −0.5065). Kernels per ear declined (b = −40.09 and b = −42.69), kernel weights declined (b = −0.4328 and b = −0.8172), and stalk lodging increased (b = 0.0103 and b = 0.0251) with increased populations for Sites WR and NR, respectively. These and previous data place the maximum population for corn in the Midsouth at about 70000 plants ha−1 No differences in yield occurred between the 224 kg N ha−1 preplant treatment and the split application of N. Yields were generally less with 112 kg N ha−1 per-plant only. Aflatoxin and fumonisin levels at both sites were unaffected by plant population of N fertility.

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