GGE axes 1 and 2 show the mapping of all varieties involved in the eight field trials (explaining ~60% of the inertia). The ideal cultivars are those with constant lowest and highest Cd values, respectively. The line relating those two represents the cultivars in which the Cd is expected to be constant across environments. This leads to the choice of the susceptible varieties (cultivars): V21 and V5.
Martin et al. BMC Genomics 2012 13:674 doi:10.1186/1471-2164-13-674