The additiin rates of cppu to increase yield
Forchlorfenuron (CPPU), a synthetic cytokinin, also may be applied at fruit set to increase berry size. It can be applied by itself, or in combination with GA3, as CPPU and GA3 may have a synergistic effect on berry size. Berries treated with CPPU tend to develop a rounder shape than non-treated berries. This compound is highly potent and normally applied at very low doses (1 to 3 mg/L); excessive doses can delay maturity, retard coloring, and have a negative influence on taste.
Caution: Plant growth regulators (PGRs), such as GA3, are classified as pesticides and are subject to the same rigorous regulatory framework. Plant growth regulators may not be approved for grapes in certain regions, or for particular cultivars of grapes. The unapproved use of PGRs on grapes may result in contaminated crops with illegal pesticide residues, so readers should seek guidance from a qualified local pest control adviser before applying any PGR to their grapes.
I have attached a video that may be of interest. I hope this helps.