Abstract
The 87Sr/86Sr ratio of horticultural products mostly derives from that of the bioavailable Sr fraction of the soil where they are growing and therefore varies according to the local geo-lithological features. This studyinvestigated the intra- and inter-tree variability of the 87Sr/86Sr ratio in two apple orchards in South Tyrol and its relation with the soil 87Sr/86Sr ratio. In both orchards, the 87Sr/86Sr ratio of each organ (shoot axis, leaf, fruit peel and fruit pulp) sampled from different parts of the same tree showed a moderate degree of homogeneity, while the 87Sr/86Sr ratio of the different tree organs sampled from the same trees was highly homogeneous. On the contrary, sampled from different trees from the same orchards showed some variability. The variability of the 87Sr/86Sr ratio within the tree and within the orchard is explained in light of the 87Sr/86Sr ratios of the soil. The variability of the 87Sr/86Sr ratio within orchards does not preclude the use of the 87Sr/86Sr ratio as geographical tracer, however, this aspect should be evaluated to correctly design a sampling campaign or to generalize the results.