Biological study of grape populations in Sardinia by a comparative seed morphocolorimetric and ecophysiological approch.

The domestic grape (Vitis vinifera L. ssp. vinifera) is considered one of the oldest crops in the world and for a long time played a role of primary importance for the ancient societies that developed around the Mediterranean basin. Nowadays, it is widely accepted that the approximately 10,000 grape cultivars, which are the result of the domestication process of V. vinifera L. ssp. sylvestris (wild grape). The domestication is the way of human transformed wild forms into domestic crops by a guided process of genetic selection and through the selection of morphological traits. For grapes, this process started 6,000-8,000 years ago in the Transcaucasian region, between the Black Sea and Iran. From this first area, the cultivated forms were spread through southern Greece to the Mediterranean region. The current panorama of cultivars is the result of wide circulation among the various wine-growing areas of the world since ancient times. However the loss of agro-biodiversity is one of the main problems that grapes are facing due to abandonment of the traditional cultivars and the spread of diseases and parasites in the nineteenth century. The thesis was focused on two aspects; the first was related with the study of seed morphology through morphocolorimetric analysis, to be used as a method for the characterization and accurate determination of cultivars. The case study was represented by Carignano and their false synonyms. The most important result was the ability of the image analysis system to correctly distinguish and classify the cultivars examined. This method offer a valid low cost tool, that allows to reach a good approximation for the correct characterization/determination of grape cultivars. Furthermore, this method allows to identify different clones that present phenotypic mutations. The second aspect investigated was the germination ecophysiology of domestic and wild grapes, with the aims of knowing the ecological requirements in the germination phase and the effect of saline stress. The study of salt tolerance in the germination phase of five Sardinian wild grape populations and these results could have important implications in order to select seeds from populations more tolerant to saltiness, which could be more resistant to salinity than the others. On the other hand, investigations of salt tolerance of the domestic grape provided new data on the ability of the Carignano cultivar to germinate in saline substrate and their resilience including high salt concentrations, this information could be useful for crossbreeding programs, or for the improvement of cultivars through sexual reproduction. In addition, dormancy release and seed germination for the domestic grape were investigated with the aims of to know the best germination conditions and to corroborate if the combination of several pre-treatments increase the germination responses using two international cultivars as models (Chardonnay and Syrah). This information can be useful in identifying the best germination protocols and to settles that the domestication process does not affect the germination ecophysiology of domestic grape.