Adjusting Source–sink Ratio through Fruit Removal Affects Dry Matter Distribution and Fruit Set in Sweet Pepper

The fruit set ratio of sweet pepper ( Capsicum annuum ) can be represented as a regression curve using the source–sink ratio (SSR) for 1 to 7 days after anthesis (DAA) because both have positive correlation. We aimed to control the fruit set ratio by adjusting the SSR for 1 to 7 DAA. The sweet pepper cv. Artega was grown for 250 days after transplantation (DAT), and the daily produced total dry matter and fruit dry weight growth were estimated to calculate SSR. Fruit removal (FR) and control (CT) plants were grown under similar conditions for 0 to 147 and 205 to 250 DAT. During 148 to 204 DAT, the SSR of FR plants was adjusted to maintain 4.0 g·g −1 by removing growing fruits, whereas that of CT plants remained unchanged. The results showed that the CT and FR plants showed similar growth until 147 DAT. Subsequently, the daily SSR of CT plants during 148 to 204 DAT fluctuated between 1.0 and 3.0 g·g −1 , whereas that of FR plants was relatively constant at 3.0 to 4.0 g·g −1 . The fruit set ratio of FR plants increased following fruit removal compared with that of CT plants, and this ratio was closely aligned with the regression curve. In conclusion, modifying the SSR through fruit removal according to the cultivar-specific regression curve allows growers to regulate fruit set as desired.