What are the reasons for grape coloring failure?
Grape growing goes through several stages, and each stage has its own characteristics. The veraison stage is one of them; veraison is when the grapes' color turns from green to dark blue. Once veraison succeeds, the grapes are basically almost ripe, but in many cases the coloring stalls at a difficult in-between stage. Although failed coloring does not affect the taste of the fruit much, the fruit's appearance will be rather unattractive, reducing its commercial value. So what are the reasons that affect grape coloring? Details are as follows:
1. Too many fruits left on the vine
As mentioned in previous articles, many fruit growers never thin the fruit on the vines in order to increase grape yields. In fact, this greatly affects both the yield and the quality of the grapes, especially during veraison, when a large amount of nutrients is needed; but leaving too much fruit on the vine leads to an uneven distribution of nutrients within the plant. Some fruits even stop coloring halfway, showing a half-green, half-red appearance. Therefore, we should thin the fruit reasonably, and the number of fruits must not exceed the vine's load capacity, otherwise all our efforts will be in vain.
2. Light
During the stage from veraison to coloring, grapes' demand for light is very important; if sufficient light time is not provided at this stage, it will affect the grapes' photosynthesis. This leads to insufficient accumulation of photosynthetic substances in the plant, making it impossible to ensure normal coloring of the fruit. Also, different grape varieties have different requirements for light duration. So the method and duration of light exposure should be determined according to the variety; during the grape coloring period, ensuring sufficient light is what allows the grapes to color smoothly and form a good appearance.
3. Fertilizer
Many fruit growers apply large amounts of nitrogen fertilizer during the grape veraison period. In fact, at this stage nitrogen fertilizer not only fails to promote grape coloring, but also affects yield and causes the grapes to turn green again. During the grape veraison period, we should apply heavy phosphorus and potassium fertilizer; phosphorus and potassium fertilizer can provide sufficient nutrients for grape coloring. Moreover, this veraison period is also the peak period of the grapes' continuous nutrient demand, so the amount of fertilizer applied should be determined according to the grapes' growth condition and quantity. It must not be too much or too little; too much will also cause branch growth, which competes for the fruit's nutrients and is not good for the fruit's growth.
4. Water
Water is also very important during the grape veraison period. Although the grapes' water demand increases during this period, waterlogging must absolutely not occur in the orchard. Too much standing water in the orchard, or even soil that is too wet, will greatly affect grape veraison. This is because during grape veraison, the roots' respiration intensifies; if the soil is too wet, the roots have difficulty breathing. This prevents the roots from producing enough energy to absorb nutrients and support the grapes' growth, which indirectly affects grape coloring to a certain extent.
The above are the main reasons for grape coloring failure; in fact, they are also some of the management tasks we need to do in cultivation. If these basic tasks are done well, there will not be much of a problem with grape coloring; most importantly, everyone needs to strengthen orchard management. Alright, that is all for today's introduction. This article is for reference only. Thank you for reading and supporting us; you can visit our website to see more related information!