At present, the ratio of branch to fruit and the ratio of leaf to fruit are commonly used as indicators to judge the suitable load of trees. However, it is impossible to determine the size of leaf area when pruning in winter. Therefore, in recent years, flower bud retention rate, flower-leaf bud ratio and branch-fruit ratio are often used as indicators to determine the appropriate fruit load. According to the investigation of relevant units in Weihai City, Hebei Province, Liaoning Province and other provinces in Shandong Province, apple trees generally have 1.500 ~ 2000 flower buds at full fruit stage, and the proportion of flower buds to the total number of buds is 1.5% ~ 20%, and spare leaf buds account for about 60%. For trees with medium growth, the ratio of flower buds to leaf buds can be kept at about 1∶3; For weak trees, the ratio of flowers to leaf buds should be kept around 1∶4; For vigorous trees, the ratio of flowers to leaf buds can be kept at about 1∶2. In this way, the number of buds per cubic meter of crown is about 15 ~ 20. Under normal circumstances, about 20 large apple trees with a crown diameter of 6-7 meters and a height of 5-6 meters can bear fruit. The yield per tree can reach about 250 kg, and the average fruit weight of small fruits is 120 ~ 150 g.

Varieties with more flowers, less fruit setting and serious flower and fruit dropping should leave more flower buds when pruning; Varieties with lighter flower and fruit dropping and higher fruit setting rate can appropriately reduce flower bud retention. According to the experience of apple producing areas in Bohai Bay, it is appropriate to control the number of flower buds per 100 cubic meter of apple trees in full fruit period in normal years, that is, the number of flower buds per cubic meter of apple trees is about 15; The ratio of flower buds to leaf buds is about 1∶3.

Branch-to-fruit ratio is a method expressed by the average number of branches per fruit, based on the fruit. According to the investigation of high-yield apple orchard in Yantai, Shandong Province, the ratio of branches to fruits is generally 3∶ 1. But when the tree potential and management level are different, the branch-fruit ratio can also be different. Strong trees can be about 2∶ 1, and weak trees can be about 4∶ 1.

The suitable range of leaf-fruit ratio and branch-fruit ratio is basically the same. According to the investigation, the average number of leaves per apple branch is 13 ~ 15. When the branch-fruit ratio is 3∶ 1, the leaf-fruit ratio is about 39 ~ 45 ∶1; When the branch-fruit ratio is 5∶ 1, the leaf-fruit ratio is about 65 ~ 75 ∶ 1. The investigation data at home and abroad show that under the current production conditions, Hongyu and other small apple varieties need to leave 30 ~ 40 leaves per fruit; Large fruits, such as Red Star, India, etc., need to leave 60 ~ 70 leaves per fruit; In order to produce high-quality red Fuji apples, each fruit should have more than 70 leaves.

Young fruit trees should not only bear fruit early, but also grow into a solid tree skeleton to prevent excessive fruit and premature aging; We can't just plant trees, which will delay the results and affect the early economic benefits. Therefore, when pruning young trees, we should not only pay attention to early yield, but also pay attention to shaping; The trees that have entered the full fruit period have formed a tree shape, which is mainly the result. When pruning, the number of flower buds should be determined according to the ratio of flower buds to leaf buds, the growth of trees and the management level. In the absence of natural disasters, fewer flower buds should be left, so that the size of the fruit may be larger and the total output will not be reduced, but the commodity value of the fruit will be significantly improved and the economic income will increase.

Trees with great growth potential, especially young trees, can leave more flower buds appropriately to slow down the growth of trees; For trees with weak growth, in order to rejuvenate the trees and prolong the fruiting period, it is necessary to leave fewer flower buds.

Orchards with good site conditions, deep soil layer, sufficient fertilizer and water, and high management level can appropriately leave more flower buds, otherwise they should leave less; Orchards that bear fruit in big and small years should be kept in big years and in small years, so as to gradually overcome the phenomenon of bearing fruit in big and small years.

On the basis of pruning adjustment, it is necessary to cooperate with thinning flowers and fruits to ensure appropriate load, effectively prevent the occurrence of big and small years, keep the tree vigorous, prolong the fruiting year and improve economic benefits.