The study looked at how two types of blackberries, Boysen and Kiowa, grow and develop. They found that blackberry fruit development happens in three stages: rapid growth, stationary growth, and mature growth. During rapid growth, the fruit gets bigger quickly but sugar and acid build up slowly. In the stationary growth stage, the fruit grows more slowly, and the acid in the fruit increases. The mature growth stage is when the fruit gets heavier and sugar and acid build up quickly. This stage is when most of the sugar accumulates in the fruit.