| Zusammenfassung: | Sangiovese is the most widely grown red wine-grape cultivar in Italy: more than 50 clones have been registered to date by breeders working in differing environments on local populations. Yet, to our knowledge, no comparative testing of these clones has been attempted in their breeding districts. It was thus deemed opportune to test comparatively eight groups of vines from a single Sangiovese clone, the SG 12T virus-indexed, in varying agronomic and environmental conditions. The investigation was also extended to a further three groups of plants from the same clone: two groups made up of the virus-indexed vines derived from buds irradiated with gamma rays and the other from vines derived from the non-indexed mother plant exhibiting symptoms of Grape Fanleaf Virus (GFV). The subsequent analyses, which were based on 34 UPOV trait descriptors, showed that: (a) the eight groups of identical origin (the virus-indexed SG 12T clone) exhibited differences for seven traits; and (b) the GFV-infected vines and those derived from gamma-irradiated buds differed from the virus-indexed SG 12T vines. The biometrie data were then subjected to multivariate canonical discriminant analysis, carried out, first, separately for phyllometric values and then jointly for both carpometric and phyllometric values. These results showed that (a) the eight identical groups gave rise to differing sets that separated along the plane formed by the first two canonical discriminant functions; (b) the carpo-phyllometric analysis separated the virus-indexed GDC-trained plants from other identical vines trained to other systems and separated the irradiated vines from the other groups; (c) the phyllometric and the carpo-phyllometric analyses separated the GFV-infected vines from all the others; and (d) the carpometric analysis sometimes confounded the groups, e. g. indicating that the virus-indexed SG 12T clone had cluster and berry traits similar to those of the GFV-infected plants. Several crop management and environmental factors determined differences in leaf and cluster typology of the virus-indexed vines having the same origin and, of course, among virus-infected, virus-indexed and the indexed and irradiated vines, the latter possibly having slight genetic alterations. Thus, if on the one hand it can be assumed that many registered Sangiovese clones have certain differences, it can also be assumed on the other that some of these clones may well prove to be identical if tested under the same conditions.
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