An intervarietal study on the architectonical characteristics of the grapevine bunch that affect its compactness

Trabajo presentado en el IX International Symposium on Grapevine Physiology and Biotechnology, celebrado en La Serena (Chile) del 21 al 26 de abril de 2013.Chemical composition and sanitary status are two important factors for the definition of grape quality. Consequently, they may vary the commercial value of grapes and grape-derived products. In this sense, bunch compactness is a trait with great relevance in this attribute, since it rnay cause heterogeneous ripeness of the berries and the occurrence and development of undesirable diseases. This trait is consequence of the interaction of many individual characteristics of the bunch, whose combination may generate the compaction of the berries along the rachis, reducing the number and size of empty spaces in the bunch structure. In this sense, different architectonical elements of the bunch have been pointed out by different authors as key factors on its definition (number of berries, length of the rachis and primary branches, length of the internodes). Nonetheless, such conclusions are based on the study of a reduced number of grapevine varieties. This work has aimed to identify the phenotypic characteristics of grapevine bunch architecture that play an important role on bunch compactness through the study of a large number of bunches (2185) belonging to more than a hundred cultivars during two vintages (2011 and 2012). After the detailed phenotyping of bunches, statistical analysis revealed that compactness is a multifactorial trait, with sorne variables having a higher implication. Among them, the length ofthe main axes ofthe rachis (length of the rachis and its primary branches) has shown an important role on the definition of bunch compactness, as well as the number of berries of the bunch. On the other hand, the number of seeds per berry has positively correlated with bunch compactness in both years of study, revealing sorne kind of relationship between both traits.Acknowledgments: Project AGL2010-15694. Fellowship BES-2011-047041.Peer Reviewe