Genotype‐by‐Environment Interactions of Barley in the Mediterranean Region

Abstract

In the Mediterranean region, progress in selection for yield in harsh environments is hampered by large environmental variation between seasons and locations. This study analyzes the genotype‐by‐environment (GE) interaction of 36 two‐rowed genotypes of barley (Hordeum vulgare L.), grown in 14 environments in Syria and North Africa. It assesses the effect of growth type (winter or spring type) and heading date on the GE interaction and determines whether or not high‐yielding (HY) environments are representative of low‐yielding (LY) ones. Average grain yield per environment ranged from 7 to 513 g m−2. Genotypes and environments were classified by a cluster analysis and the interaction was analyzed with an additive main effects and multiplicative interaction model. Genotypes were classified into four clusters, related to their growth type and earliness of heading. Environments were clustered in a HY and LY group; this classification was related to seasonal rainfall and temperature. Medium‐early heading winter types had a positive interaction with LY environments and a negative interaction with HY environments, whereas late heading genotypes (spring and winter types) had the opposite interaction pattern. Early heading spring types had above‐average mean yields; the highest‐yielding among them tended to have a low interaction with environments. High‐yielding environments did not discriminate well between genotypes with high or low yields in LY environments, and may thus have limited value for yield selection for LY environments. For a breeding program aimed at improving yield in environments where favorable conditions are rare, selection for yield should be done in representative less‐favorable environments.