Definition - What does Fruitful Bud mean?
A fruitful bud is a bud that has at least one developing cluster. Some buds can have two or more clusters. These clusters start developing before bloom during the previous year's growing season. Each bud can become a shoot or a fruitful bud. The development of fruitful buds is determined by how much light exposure the developing shoots and buds receive.
WineFrog explains Fruitful Bud
When grapes go into their dormancy period, the maximum crop potential for the following growing season is already determined. Each compound bud can potentially produce three shoots. They also have a fixed number of cluster primordia. These are the buds which are selected during the dormant pruning stage.
Vine training systems put in place for vine growth are designed to provide enough sunlight to buds in order to increase the number of fruitful buds. The greater amount of sunshine a bud is exposed to, the greater chance it will become a fruitful bud. This can also help determine the potential yield.