The aim of this study was to assess the fertility and C and N reserves in buds of shoots at the beginning of dormancy and complete dormancy of 'Cabernet Sauvignon' and 'Nebbiolo' varieties. In a 'Cabernet Sauvignon' and 'Nebbiolo' vineyard in São Joaquim (SC), buds were collected from new shoots at the beginning of dormancy (May 2012) and at complete dormancy (August 2012) according to the following treatments: (T1) basal buds (1st to 5th), (T2) medial buds (6th to 10th) and (T3) apical buds (11th to 15th). Three shoots were collected from each plant, one located on the left side, one on the right side and the third in the center of the plant. Determination of the presence or absence of the beginning of inflorescence was performed only in the buds collected in complete dormancy, using a stereo microscope. The contents of total soluble carbohydrates, starch, total proteins, total organic carbon, total nitrogen and C/N ration were determined in buds at the beginning of dormancy and in complete dormancy. 'Cabernet Sauvignon' exhibited a greater number of fertile buds in the medial portion of the new shoots. But in the 'Nebbiolo' cultivar, the greatest number of fertile buds was observed in the medial and apical portions of the shoot. The greater carbon reserves in the 'Cabernet Sauvignon' buds may be responsible for the greater fertility of the buds. The fertile bud load in 'Cabernet Sauvignon' can be increased through medium to light winter pruning and in 'Nebbiolo', through light pruning above the 6th bud, as in Guyot.
Carbon; nitrogen; carbohydrates; Vitis vinifera L.
