Bottom panel: relation between [Y/Fe] and metallicity [Fe/H] for cluster giants analysed in the present study (red filled squares). Literature data (Stars 2, 151 and 201 in NGC 5822, from Katime Santrich et al. 2013; Sales Silva et al. 2014) are depicted by red open squares. For the sake of clarity, stars with identical metallicities have been slightly shifted vertically. Field giants, from Luck & Heiter (2007) and Mishenina et al. (2007), are depicted by small (respectively black and blue) crosses. The barium star HD 104979 is part of the Luck & Heiter (2007) sample and is identified by a crossed square. Top panel: the normalised distribution of [Y/Fe] for the field giants is represented by the unshaded histogram. The shaded histogram corresponds to the cluster giants (including some barium stars) from the present study.