Generally speaking, harvesting occurs in late summer and autumn. Early-ripening apples can be harvested in early July, while late-ripening apples are harvested at the end of September. The specific harvest season for apples will vary depending on the local climate and apple varieties.

1. Flowering

The flowering period of apples varies greatly depending on the climate in different places. Generally in April to May, each flower bud has 3 to 7 flowers, and the central flower blooms first. Apples are cross-pollinated plants, and most varieties are self-flowering and cannot produce fruit. The proportion of various types of fruiting branches varies depending on the age and variety of the tree.

Usually young trees have more long fruit branches and medium fruit branches. As the age of the tree increases, the proportion of short fruit branches increases rapidly. By the time of the fruiting stage, it can generally reach more than 70%. During the senescence stage, it is almost entirely Short fruiting branches. In terms of varieties, varieties such as Jinshuai have more long fruit branches and medium fruit branches, varieties such as New Red Star and Red Fuji have a larger proportion of short fruit branches, and varieties such as Liaofu are prone to axillary flower buds.

2. Fruit setting

The normal apple fruit has 5 ventricles and 2 seeds in each ventricle. During the fruit development process, the seeds secrete hormones to stimulate the growth of the pulp. Therefore, those with good pollination and fertilization and plump seeds will have a correct shape and plump flesh. On the contrary, those with poorly developed seeds or no seeds will have sunken and thin flesh, resulting in deformed fruits. Therefore, Be sure to configure pollinating trees and improve pollination.

Extended information:

The apple fruit is a false fruit developed from an ovary and a receptacle. The ovary develops into a fruit core, the receptacle develops into a pulp, and the embryo develops into a seed. The expansion of fruit volume depends on the increase in the number of rapidly dividing cells in the early stage and the expansion of cell volume in the later stage.

The expansion of fruit size is faster from the middle stage to before maturity, and slower in the early and late stages. Fruit weight increases fastest in the month before maturity. The length of fruit development period is generally 65-87 days for early-maturing varieties, 90-133 days for mid-maturing varieties, and 137-168 days for late-maturing varieties. Fruit color is an important indicator of commodities.

The quality of apple coloring is closely related to the accumulation of sugar, coordination of mineral elements, environmental conditions and hormone types and contents. In the later period, controlled application of nitrogen fertilizer, increased application of potassium fertilizer, reduction of chlorophyll in the peel, improvement of ventilation and light transmission conditions, increase of sunlight exposure, good drainage, reduction of air humidity, and spraying of hormones such as naphthalene acetic acid and 2.4-D can all promote apple growth. color.

Apples generally drop flowers and fruits four times from the time the flower buds appear to the time the fruits are harvested. For the first time, during the final flowering period, the pedicels fall off together with the flowers, which is usually called flower drop. The second time, about a week after the flowers fall, the ovary slightly enlarges and lasts for 5 to 20 days, which is called early fruit drop.

The third time, 7 to 14 days after the second fruit drop, the fruit has reached the size of a thumbnail, which has a greater impact on yield. It is called physiological fruit drop. It usually occurs in May in Yunnan, and the phenology in the north is The period is later than that in Yunnan and occurs in June, so it is called "June fruit drop".

For the fourth time, mature or nearly mature fruits fall before the fruit is harvested, so it is called preharvest fruit drop. The first and second flower and fruit drop are mainly caused by nutritional deficiencies and poor pollination and fertilization. The third fruit drop is caused by intense competition for nutrients between fruits and shoots, in addition to lack of intraembryonic auxin.

Because the osmotic pressure of leaves is greater than that of young fruits, the competition for nutrients is stronger than that of young fruits. Therefore, in addition to topping and pruning of branches to inhibit the growth of new shoots, flower flower fertilizer should also be applied in time. , supplement nutrients.

Reference: Baidu Encyclopedia-Apple