Trends of the [Mg/Fe] − [Fe/H] sequences for the thick disc (plain line) and thin disc (dashed line), for different signal-to-noise (S/N) threshold limits close to the plane (0 < | Z | < 1 kpc, left column) and far from it (1 < | Z | < 2 kpc, right column). The top, middle, and bottom rows show the Gaia-ESO iDR2 results for the inner Galaxy, solar suburb and outer Galaxy, respectively. The over-plotted grey points in the panel 7.5 <R< 8.5 kpc and 0 < | Z | < 1 kpc are the α-abundance measurements of Adibekyan et al. (2013), obtained for a very local sample (d ≲ 150 pc). No significant differences in the derived trends are found as a function of S/N, which is indicative of the robustness of our fitting method.