In the field of grape cultivation, uneven grape sizes have always been a problem that troubles farmers. This not only affects the appearance of the grapes but also reduces their market competitiveness. Recently, with the advancement of agricultural technology and the improvement of planting techniques, methods to prevent and control uneven grape sizes have gradually emerged.
I. Causes of uneven grape sizes
There are various reasons for uneven grape sizes, including uncontrolled fertilizer and water management, improper pruning, improper fertilization, and improper management during the flowering period. Specifically, excessive nitrogen fertilizer application, excessive watering, unbalanced tree vigor due to improper pruning, excessive use of chemical fertilizers while neglecting organic fertilizers and trace element fertilizers, and early pinching and bending of flower buds during the flowering period can all cause uneven grape sizes.
II. Methods to prevent and control uneven grape sizes
Precise fertilizer and water management: Control the amount of nitrogen fertilizer applied, and water rationally to avoid overwatering. Before flowering, the soil 10 centimeters below the surface should be able to form a ball when squeezed by hand. Generally, two waterings before flowering are sufficient. In low-lying or heavy clay soil, one watering or no watering is recommended. After fruit setting, when the fruit reaches the size of a soybean, apply large amounts of fertilizer and water. From the hardening of the core to the coloring period, apply more phosphorus and potassium fertilizers.
Reasonable pruning: Control the tree vigor and maintain the balance of the tree through pruning. For result branches with a distance of more than 20 centimeters, multi-bud pruning should be adopted to fill the gaps. However, during bud thinning and branch selection in the following spring, keep two buds at both ends and remove the middle ones, maintaining a proper branch distance.
Reasonable fertilization: According to the growth needs of grapes, rationally combine organic and chemical fertilizers. Do not apply nitrogen fertilizer before flowering, and apply less or no organic fertilizer. After fruit setting, when the fruit reaches the size of a soybean, apply large amounts of fertilizer and water. From the hardening of the core to the coloring period, apply more phosphorus and potassium fertilizers. Additionally, pay attention to supplementing zinc and boron fertilizers and other trace elements to promote normal growth of grapes.
Flowering period management: The time for pinching and bending flower buds during the flowering period should not be too early. Generally, it is appropriate to do it 3 to 5 days before flowering. For double-bud result branches, leave one long and one short bud when pinching, with the short bud having 6 to 8 leaves and the long (strong) bud having 8 to 10 leaves. For fruit clusters less than 10 centimeters long, do not pinch or pinch less. For clusters around 20 centimeters long, pinch off 1/5.
Use of growth regulators: When the grapes show obvious size differences (about 15 days after flowering), immerse the clusters in a growth regulator solution once (or spray evenly on the fruit). However, pay attention to the dosage and timing of the growth regulator to avoid negative impacts on grape quality.
Variety selection: Plant grape varieties that are less prone to uneven sizes, such as Red Beauty, Honey King, and Purple Treasure. For already planted varieties, solutions such as variety replacement or seedlessness treatment can be adopted.
