Syrah; High altitude Cerrado; Bud fertility, Carbohydrate reserve, Pruning management.

The new Brazilian wine-growing frontiers extend across several states and are established in almost all regions of Brazil, including the Cerrado de Altitude of the Integrated Development Region of the Federal District and Surrounding Area (RIDE-DF). Characterized by its high-altitude tropical conditions, local viticulture adopts specific practices such as double pruning management. Double pruning is adjusted so that a formative pruning and a productive pruning occur, resulting in an annual harvest between the months of July and August. The differentiation and development of the vine buds occur in two distinct cycles and are essential for the formation of fertile buds, which directly influence the productivity of the vine with the double pruning management. Floral induction and differentiation, which lead to the formation of reproductive structures, is a complex process di- vided into three stages: formation of the anlage (undifferentiated primordium), development of the inflorescence primordium and, finally, the development of the flowers. In double pruning management, the initial stages of formation of the an- lage and inflorescence primordia begin in the formation cycle, after pruning per- formed in September, and are completed at the beginning of the production cycle with the formation of flowers, after production pruning between February and March. It is important to reiterate that double pruning management can negatively impact the formation of the anlage and inflorescence primordia, resulting from nutritional and water management that will influence the biochemical, physiolog- ical and morphological events of the vine. The formation of inflorescence primor- dia during the formation cycle will determine the potential number of inflores- cences and, in the future, the number of bunches that will be produced in the following cycle. This study aims to evaluate the morphological analysis technique for fertility, as well as to quantify the concentration of carbohydrate reserves in buds, providing technical support for winegrowers to adjust the most favorable pruning time and bud load in the most appropriate pruning management for local soil and climate conditions. Random samples were collected from ten vineyards in the integrated development region of the Federal District (RIDE-DF), consisting of fifteen shoots in each vineyard for morphological analysis of the buds. The samples included the first fifteen uncut buds and were classified as basal (1st to 5th), middle (6th to 10th) and apical (11th to 15th) buds. The morphological anal- ysis was performed in the laboratory, using a stereoscopic magnifying glass, and the data were categorized as fertile (mixed), vegetative, necrotic and absent buds. In the same vineyards, samples of the first three basal buds of the shoots were collected from ten randomized shoots in the vineyard in three replicates. The buds were cut, leaving one centimeter of shoot wood above and below each of the three basal buds. The bud samples were dried in an oven (Vulcan, Oven: Sterilization and drying 300°C - 150 liters) at 65°C for five days, and ground in a knife mill (Marconi - MA 340) with a 2.0 mm sieve. Carbohydrate quantifications were performed with the samples following the methodology (Association of Offi- cial Analytical Chemists, for determination of resistant, non-resistant and total starch) in triplicate. The data obtained will be subjected to analysis of variance (ANOVA) and the means compared by Tukey's test at 5% probability, using the free software Assistat 7.7 pt. The bud morphology results showed that basal buds presented a fertility of 77%, with 7.3% vegetative, 11% necrotic and 5.3% absent. The median buds showed a significant increase in fertility, with 91% of the buds fertile, 2.4% vegetative, 5.3% necrotic and 0.9% absent. The apical buds pre- sented a fertility of 79%, with 4.7% vegetative, 6% necrosis of the main cone and 10% absent. The average fertility of the buds was 76.53% in the basal, 91.33% in the median and 79.2% in the apical, evidencing a significant increase in the fertility of the median buds. The analysis of the distribution of fertile buds and the conditions of the buds in the ten properties evaluated indicate that the adoption of long production pruning is the most recommended management to improve vineyard productivity in RIDE-DF. This approach, combined with the understand- ing of the mechanisms of concentration and availability of carbohydrates to the buds, will allow winegrowers to maximize production by adjusting their pruning management practices based on the fertility and accumulation of bud reserves and the specific characteristics of each vineyard in the high-altitude Cerrado Ter- roir.