Experts, how do black grapes turn red quickly in summer?

Hello, in summer, you can spray amino acid red promotion drugs and 20 ml ethephon potassium-increasing foliar fertilizer once, and then gradually increase ethephon 10 ml each time. You can also add 50 ml abscisic acid and high potassium water-soluble fertilizer to the amino acid red-promoting drug, and pay attention to the application of potassium fertilizer. My latter is more effective, for reference only, and adapted to local conditions.