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Crop Science Abstract -

Efficiency of High-Nitrogen Selection Environments for Improving Maize for Low-Nitrogen Target Environments


This article in CS

  1. Vol. 37 No. 4, p. 1103-1109
    Received: July 16, 1996

    * Corresponding author(s): M.BANZIGER@CGNET.COM
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  1. M. Bänziger ,
  2. F. J. Betrán and
  3. H. R. Lafitte
  1. Intl. Rice Res. Inst. (IRRI), P.O. Box 933, 1099 Manila, Philippines



Most maize (Zea mays L.) in the tropics is grown under low-nitrogen (N) conditions, raising the need to assess efficient breeding strategies for such conditions. This study assesses the value of low-N vs. high-N selection environments for improving lowland tropical maize for low-N target environments. Fourteen replicated trials grown under low (no N applied) and high (200 kg N Ha1 applied) N at CIMMYT, México, between 1986 and 1995 were analyzed for broad-sense heritability of grain yield, genetic correlation between grain yields under low and high N, and predicted response of grain yield under low N to selection under either low or high N. Broad-sense heritabilities for grain yield under low N were on average 29% sm ller than under high N because of lower genotypic variances under low N. Error variances were similar at low and highN. Genetic correlations between grain yields under low and high N were generally positive. They decreased with increasing relative yield reduction under low N , indicating that specific adaptation to either low or high N became more important the more low-N and high-N experiments differed in grain yield. Selection under high N for performance under low N was predicted significantly less efficient than selection under low N when relative yield reduction due to N stress exceeded 43%. Maize breeding programs targeting low-N environments in the tropics should include low-N selection environments to maximize selection gains.

Contribution from the Int. Maize and Wheat Improvement Ctr. (CIMMYT), Apdo. Postal 6-641, 06600, México D.F., Mexico.

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