Several investigations describe the time or the phenological stage of formation of the inflorescence primordial of the vine. The reports are however contradictory, possibly due to differences in climatic conditions among production regions. A trial was carried out aiming at to determine when fertile buds are developed in grapevine cv. Italia, in two production regions of São Paulo State, Brazil: Jales and Jundiaí., Five canes in each vineyard were sampled every 15 days after sprouting. Up to the 15th node of each cane the buds were dissected and examined under stereomicroscope for presence of inflorescence primordia. Percentage of fertile buds from the stage 5 (E5), percentage of fertile buds with full mature primordial on stage 7 (E7) and coefficient of fertility (relation between number of inflorescence primordia/number of total buds) were rearded. It was verified that the beginning of inflorescence primordia (E5) occurred at the 30 days after sprouting. The formation of inflorescence primordial fully mature (E7) took place between 45 and 75 days, corresponding to the phenological stages of flowering and "pea-grain", respectively. In Jales vineyard, the percentage of fertile buds was higher, irrespective of the sample time, possibly because of its superior daily temperature averages.
Vitis vinifera; grapes; physiology; flowering
