1. Reasonable fertilization
During the grape color transition period, it is necessary to do a good job in fertilization, control the amount of fertilizer applied, and avoid excessive fertilization. Especially nitrogen fertilizer, if applied too much, it can lead to the phenomenon of late ripening of grapes, thereby affecting the coloring of grapes.
When fertilizing, attention should be paid to controlling the proportion of nitrogen, phosphorus, and potassium fertilizers, and supplementing organic fertilizers appropriately, with potassium fertilizer as the main fertilizer.
In addition, attention should also be paid to supplementing nutrients such as calcium and magnesium, which can be supplemented by spraying phosphorus dioxide on the leaf fertilizer to ensure normal coloring of grape fruits.
2. Lighting control
Light is very important for grape flower bud differentiation, and it also has a significant impact on grape fruit coloring. Both light intensity and time directly affect the coloring of grapes.
In general, to achieve normal coloring of grape fruits, the natural light intensity should be around 70%. So we need to pay attention to controlling the light and promptly remove the ear near the fruit, as well as some old and diseased leaves that may block the light.
For robust leaves, appropriate removal is necessary, and bagged fruits should be promptly bagged in the later stages to promote coloring. If it is a late maturing variety, then reflective film should be laid in the garden.
3. Water management
Although grapes have a certain demand for water during their growth process. But it is important to pay attention to controlling the amount of water used, especially during fruit ripening and coloring.
If there is too much watering or rainfall without water accumulation and drainage, it will lead to an increase in fruit moisture content, thereby reducing the sugar content and anthocyanin concentration of the fruit, and affecting the coloring of the fruit. So when coloring the fruit, it is important to maintain a relatively dry environment.
After the grapes enter the turning stage, they should be watered with small drops and a small amount of water. They should not be flooded with large amounts of water. If there is rainfall, they should be drained in a timely manner.
