Grape flowering and fruit dropping are mainly caused by too fast nutrient growth, insufficient light, fertilizer and water, insufficient phosphorus, potassium and boron, and inappropriate temperature. Taking appropriate field management measures, reducing the amount of nitrogen fertilizer, applying phosphorus and potassium fertilizer, supplementing boron fertilizer and calcium fertilizer, and spraying potassium dihydrogen phosphate plus amino acid foliar fertilizer plus boron fertilizer plus brassinolide on the leaves can improve the fruit setting rate and protect flowers and fruits.
Grape blossom and fruit drop are caused by factors such as heavy load, tree growth, serious fruit drop, imbalance of fertilizer and water, lack of boron and calcium, insufficient nutrient supply, poor photosynthesis and poor root activity. Pay attention to balanced fertilization, reasonable load, thinning fruits and vegetables, spraying potassium dihydrogen phosphate, calcium amino acid foliar fertilizer and brassinolide on leaves to prevent fruit drop.
Flowering and fruiting are mainly caused by excessive nitrogen fertilizer, insufficient phosphorus and potassium, insufficient fertilizer, water and light, lack of boron and calcium fertilizer. It is suggested to reduce the amount of nitrogen fertilizer, apply phosphorus and potassium fertilizer, and spray sodium cyclamate calcium or pbo before flowering to regulate leaf growth. Spraying Bihu+Su Le boron+calcium chelate can promote flower bud differentiation and improve fruit setting rate.
A week before and after the flowering of grapes, the flower buds and ovaries fall off, which is called flower drop and fruit drop disease, and the rate of flower drop and fruit drop is above 80%. Grape blossom and fruit drop refers to physiological flower and fruit drop caused by internal reasons of trees, excluding flower and fruit drop caused by pests and diseases and strong winds. Like other fruit trees, falling flowers and fruits of grapes is a physiological disorder in the body. If it is light, it will not affect the yield, and it belongs to normal flower drop and fruit drop. If it is heavy, the fruit setting rate is very low, resulting in a large area of production reduction, which can be described as abnormal flower drop and fruit drop. After the grapes wither, there is a physiological phenomenon of falling flowers and fruits. The peak of flower drop is within 1 week after flowering, and then it will drop sporadically and gradually stabilize.
Variety characteristics: for example, the pollen of female flower varieties has no germination holes, and the reproductive nuclei and vegetative nuclei in pollen grains are degraded. If there is no suitable pollination variety, it is difficult to set fruit. There are also some varieties with high ovule abnormality rate, such as Kyoho ovule abnormality rate of 48%. These are the main genetic factors that cause a large number of falling flowers and fruits. Different varieties have different degrees of falling flowers and fruits.