Fruit expansion is a critical period for fruit trees to bear fruit and require nutrients. Paying attention to water and fertilizer management during this period is crucial for increasing yields. It's important to note that the fruit sweetening and expansion phases are two separate stages, with different nutrient requirements and different water and fertilizer recommendations.

Fertilizer Requirements During Apple Fruit Expansion

There's a popular saying: "Nitrogen grows branches and leaves, phosphorus promotes flowering, and potassium is most beneficial for fruit expansion; applying potassium in July and August results in larger fruits and enhanced color." This suggests that apples' potassium requirements increase during the later stages of topdressing. However, fruit expansion and sweetening are relatively close phases. A lack of nitrogen fertilizer can result in smaller leaves, shorter branches, fewer buds, and sluggish growth. Furthermore, excessive nitrogen application can lead to an increase in fruit deformities. Therefore, nitrogen fertilizer application should be controlled.

After the fruit expands to a point where biological patterns are met, the fruit begins to store sugars. During this period, it absorbs a significant amount of potassium and phosphorus fertilizers. In addition to applying potassium fertilizer to the roots, foliar spraying with Huadeguo potassium phosphite or soluble potassium fertilizers can significantly promote the growth of young fruit.

Furthermore, trace elements are essential for fruit expansion, quality preservation, and yield. For example, during the expansion period of apples, calcium deficiency increases the incidence of fruit cracking and makes the fruit difficult to store. Magnesium deficiency shortens the ripening period and affects overall yield. Zinc deficiency causes leaf clustering, which robs the apples of nutrients, resulting in smaller apples and reduced quality. When fertilizing apples during the expansion period, special attention should be paid to trace element intake.

Foliar topdressing during the expansion period is recommended. Rosia's phosphorus, potassium, and calcium fertilizers can provide excellent nutritional support, minimizing the impact of deficiencies on apple growth, sweetening, and quality.