Causes of poor coloration of grapes

First, the excess nitrogen fertilizer fruit yin and yang face: farmers are aware of nitrogen fertilizer plant are the elements of life, the pursuit of high-yield more productive, they overdose of nitrogen fertilizer, the result is: (1) leggy branches, ripe fruit can not be normal, vulnerable to frost Mold damage, early leaves of plants, poor cold resistance of branches. (2) The fruit taste is poor, the coloration is uneven, the yin and yang face is formed, the solid content is low, the cooked variety has no storage value, and the loss rate is high during storage.
Second, the excessive application of potassium fertilizer is not good for color enhancement: due to the false propaganda and misleading of fertilizer distributors and manufacturers “multiple application of potassium fertilizer and sugar-increasing coloring”, many farmers over-apply potassium fertilizer, resulting in potassium poisoning in the tree: starting from the middle and lower parts of the branches The oily yellowing of the edge of the blade, the natural coloration of the expected fruit has not been achieved.
In fact, in the process of grape growth, potassium fertilizer has the effect of promoting the fatness of flesh, but the effect on sugar-staining is not so magical to manufacturers and distributors. Excessive application of potassium fertilizer not only inhibits the absorption of magnesium, but also inhibits the absorption of phosphorus. In the coloring process, calcium can promote the sugar produced by the leaves to the fruit, and play a role of "sweating sugar". Magnesium and zinc are activators of various enzymes in plants, which play an important role in the color change of grape skin. Because grapes absorb less zinc and have a relatively high absorption of magnesium, magnesium is the key to grape coloration.
There are three main types of potassium fertilizer applied in grape fields: potassium sulfate, potassium nitrate, and potassium dihydrogen phosphate. So, what potash is a better potash? Potassium dihydrogen phosphate. Potassium sulphate causes soil acidification, and potassium nitrate contains nitrogen, which stimulates growth. Potassium dihydrogen phosphate contains potassium and has a total nutrient content of about 86%. Phosphorus promotes flower bud differentiation and potassium promotes sugar synthesis. It is also a physiologically neutral fertilizer that does not cause soil acidification and does not affect the absorption of calcium, magnesium and zinc. Therefore, after the grape flower to the color change period, the potassium dihydrogen phosphate can be used for early coloring for about one week. In the color changing period, potassium dihydrogen phosphate is applied for 5 to 8 kg per mu.
3. Neglecting the application of phosphate fertilizer. The color is dark and the taste is poor. In the whole production process, people have neglected the role of phosphorus. Phosphorus plays a role in the plant body, so that various elements accelerate in the plant, and the grapes grow and turn. The efficacy of the color sugar increase process cannot be ignored. The photosynthesis of plants is poor after phosphorus deficiency, and the fruit color is gray, no light, and the taste is poor.