La selezione clonale del "Sangiovese" nella Maremma Toscana

The selection area is located in the coastal provinces of Tuscany, with special reference to the Doc Morellino di Scansano zone (province of Grosseto) and the Val di Cornia (province of Livorno). Clonal selection was carried out according to the procedures specified by the official genetic and plant health selection methods, in conformity with recent guidelines supplied by the National Committee for the homologation of grapevine material, implemented by the Region of Tuscany. The present study reports on a series of ampelographic observations performed during the two-year period 1997-98 on presumed clones identified in old vineyards, between 30 and 40 years of age or older, composed of native material. These constitute a source of genetic mate-rial endowed with sufficient varia¬bility of characters. Selection criteria concerned above all the following parameters: morphological differences of leaves (size, tomentosity and other characters) and of grapes (skin thickness, size, pulp/skin ratio), moderate productivity, limited vigor, cluster characteristics (preferably not tight), with particular emphasis on cluster shape and size. Selection also focused on grape phenologic characteristics and technological potential (sugar content, pH, total acidity, anthocyan and polyphenol content). The main aim in selection was to identify a sufficient number of mother grapevines within the existing population of each zone studied to ensure representation of broad variability of the above-mentioned characters. In addition, during the selection process priority was given to characters considered most favorable for current grapevine growing objectives. The present paper reports on results of a two-year observation period on 12 presumed clones identified in the Val di Cornia and 18 identified in the Morellino Ai Scansano zone, all of which tested negative on the ELISA test. Ampelographic shoot, leaf and cluster observations showed appreciable differences among the presumed clones investigated. In each of the two selection areas it proved pos-sible to identify groups of presumed clones classifiable into one or more biotypes, distinguished by cluster and grape characteristics including phenol concentration.