Selection Efficiency across Environments in Improvement of Barley Yield for Moderately Low Nitrogen Environments

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Developing barley (Hordeum vulgare L) cultivars suitable for low‐N conditions is important for sustainable production. In breeding for low‐N environments, it must be decided whether a separate breeding program is necessary for this environment or if it can be performed as part of a multienvironmental testing and selection strategy. The objective of this study was to determine the efficiency of indirect selection based on performance under the traditional multiple high N environments versus direct selection under the low‐N conditions. Twelve experiments, each consisting of 18 to 25 barley genotypes, were conducted in five to eight environments including a low‐N environment in Alberta, Canada, from 2001 to 2006. The low‐N conditions used in this study simulated reduced N application as would be used to produce malting barley in western Canada, so the level of N‐stress imposed would be considered moderate. Genetic correlations between mean grain yield across multiple high N environments and the yield in the low‐N trial was positive and high, ranging from 0.83 to 1.00. The predicted correlated response in grain yield under low N to selection based on mean yields across multiple high‐N environments relative to the predicted response to direct selection in the low‐N environment ranged from 0.81 to 1.18. This implies that breeding for low‐N conditions relevant to malting barley cultivation in western Canada and similar circumstances can be performed as part of the selection strategy for broad adaptation.