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This article in CS

  1. Vol. 42 No. 4, p. 1129-1134
    Received: May 12, 2000

    * Corresponding author(s): legouis@mons.inra.fr
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Diallel Analysis of Winter Wheat at Two Nitrogen Levels

  1. J. Le Gouis *,
  2. D. Beghin,
  3. E. Heumez and
  4. P. Pluchard
  1. INRA, Domaine de Brunehaut, 80200 Estrées-Mons, France


Price reduction and environmental concerns advocate a lower use of nitrogen (N) fertilizer on the wheat (Triticum aestivum L.) crop. It is a common hypothesis that hybrids would be more valuable in stressed environments such as limited fertilizer conditions. The objective of this study was to assess heterosis and combining ability at two N levels. Seven winter wheat cultivars were used to produce a 7 × 7 diallel cross without the reciprocals. The 21 F1 hybrids and parental lines were tested in replicated plots over 2 yr without N fertilizer (N0) or with 150 kg N ha−1 (N+). The diallel analysis was conducted according to Griffing with year, genotype, and treatment as fixed effects. Mid-parent heterosis for grain yield was +12.2%** at N0 and +8.9%** at N+ in 1997 and +1.7%ns at N0 and −0.4%ns at N+ in 1998. This was directly related to high mid-parent heterosis for above-ground dry weight in 1997 (+11.2%** at N0 and +10.9%** at N+) and low heterosis in 1998 (+1.2%ns at N0 and +0.0%ns at N+). General (GCA) and specific (SCA) combining ability effects were always significant. The GCA/SCA ratio ranged from 3.6 to 14.8. The GCA × N level interaction was generally significant indicating different parental contributions at low or high N levels. The SCA × N level interaction was never significant. There was a tendency toward higher GCA/SCA ratio at N0 than at N+. The choice of parents will be dependent upon the N level under which the new hybrids will be grown.

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Copyright © 2002. Crop Science Society of AmericaPublished in Crop Sci.42:1129–1134.