Morphological characterisation of Vitis vinifera L. seeds by image analysis and comparison with archaeological remains

In archaeobotanical studies, the taxonomic classification of diaspores has usually been done by simple morphological observation and visual comparison with ex situ collections of seeds, although the use of biometric indices has often proved to be a powerful approach in the taxonomic studies of the genus Vitis as well as for the species attribution of archaeological remains. Using image analysis techniques, seeds from two Sardinian archaeological sites, the pre-Nuragic and Nuragic complex of Sa Osa in central-western Sardinia, attested as the oldest Sardinian archaeological site with remains of Vitis seeds, and the Isola di Coltellazzo in southwest Sardinia, were selected and characterized on the basis of morphological features and Elliptic Fourier Descriptors. Moreover, seeds of five modern populations of V. vinifera ssp. sylvestris collected from southwest Sardinia and the seeds of 41 cultivars of V. vinifera ssp. vinifera mainly from southern and central-western Sardinia were also analysed by computer image analysis. The obtained data were used to implement a database of biometric parameters and to compare the unknown archaeological seeds with the characterized recent seeds, using Linear Discriminant Analysis. The similarity of the archaeological seeds to V. vinifera ssp. vinifera cultivars rather than to V. vinifera ssp. sylvestris populations could allow it to be stated that, between the Middle and Final Bronze Age, varieties very close to modern V. vinifera ssp. vinifera were already being used to produce wine and/or to be preserved for foodstuffs. Moreover, the better matching of the archaeological seeds to white grapes rather than black grape cultivars could indicate the origins of the traditional cultivation of white grapes in these regions of Sardinia.