Abstract
The effects of the application timing and concentration of N-(2-chloro-4-pyridyl)-N’-phenylurea (CPPU) on fruit quality of ‘Shine Muscat’ grape were investigated. Spraying the bunch with 2 ppm CPPU before blooming or 10 ppm CPPU application in addition to 25 ppm GA3 at full bloom significantly improved the tightness of the fruit bunch and decreased pericarp browning. Sensory tests revealed spraying the bunch with 2 ppm CPPU before blooming and 10 ppm CPPU application in addition to 25 ppm GA3 at full bloom decreased the hardness of the flesh, increased the hardness of the pericarp, and decreased the palatability of the berry. Spraying the bunch with 2 ppm CPPU before blooming and 10 ppm CPPU application in addition to 25 ppm GA3 at 10–15 days after full bloom markedly increased the hardness of the pericarp. Spraying the bunch with 2 ppm CPPU before blooming significantly increased the thickness of layers of epidermal and subepidermal cells. These results suggest that spraying the bunch with 2 ppm CPPU before blooming, dipping the bunch in a mixed solution of 25 ppm GA3 and 5 ppm CPPU at full bloom, and dipping the bunch in a solution of 25 ppm GA3 10–15 days after full bloom, switching from the standard methods in Shimane prefecture (dipping the bunch in a mixed solution of 25 ppm GA3 and 3 ppm CPPU at full bloom and dipping the bunch in a solution of 25 ppm GA3 10–15 days after full bloom), are effective for improving marketability.
