Top panel: [α/Fe] abundances as a function of total cluster magnitude for Si and Ca alone. Points are colour coded by age. Lower panel: same as the upper panel, but identifying clusters in the AMR metal-poor branch (blue points), the AMR metal-rich branch (red points), and the old metal-poor population (black points). The solid blue and red lines correspond to the linear fit of the metal-poor and the metal-rich branch clusters, respectively. An anti-correlation of the [SiCa/Fe] abundance with the total magnitude (r = −0.59) seems to be present only for metal-poor branch clusters.