(1) Variety characteristics
Different varieties have different growth and fruiting habits, so the method and degree of pruning must be changed accordingly. For example, the flower buds of Japanese pear varieties such as Niigata and New Century are mostly axillary. When pruning, most of them are medium-long fruit branches. However, the 2-3 year-old branches of Xiyang pear are mostly terminal buds. In order to achieve the same growth effect, the pruning should be less and shorter, and the nutrients should be concentrated on the terminal buds. This will not only bear fruit early, but also expand the crown quickly. Zaomei crisp pear has strong germination ability, but weak branching ability. When pruning, the number of branches should be increased by pulling and cutting rather than thinning branches. However, varieties with relatively weak germination ability and branching ability, such as July crisp, should be properly chopped to promote germination and branching.
(2) Natural conditions and cultivation techniques
Different natural conditions and cultivation techniques will have different effects on the same variety. Therefore, the local climate, soil, fertilizer and water conditions, planting density, rootstock types, pest control and so on should be considered when pruning. Generally, in places with long growing season, high temperature and rainy weather, or flat terrain, deep and fertile soil layer and abundant fertilizer and water, fruit trees flourish, with many branches and large crowns, which are sensitive to pruning. Therefore, it is advisable to adopt a large crown, with a higher trunk, fewer main branches, larger interlayer spacing, lighter pruning, more thinning and less short cutting. On the contrary, in mountainous areas with short growing season, cold and drought, poor soil, insufficient fertilizer and water, insufficient sandstorm or high groundwater level, the growth of fruit trees is weak, the fixed trunk is lower, the spacing between layers is smaller, the pruning amount is heavier, the short cut is more, and the thinning is less. In addition, the pruning methods of dwarf rootstocks, close planting and mechanized management should also be changed accordingly.
(3) Age and potential of trees
Young trees grow vigorously, and the requirements for cultivation in this period are early formation and moderate fruit; The tree vigor gradually eased during the full fruit period, and the cultivation required high and stable yield, and the period of full fruit period was prolonged; In the aging period, the tree is weak, and the requirement of cultivation is to renew, rejuvenate and restore the tree. Therefore, the amount and method of pruning should be different at different ages. Pruning amount and pruning method vary with different tree potentials. For strong and lush trees, sparse more and cut less; For weak trees, cut more and sparse less.
(4) Tree structure
When pruning, we should consider whether the number ratio, distribution position and growth potential of main branches and fruiting branches are reasonable, balanced and coordinated. If the main branches and fruiting branches are not properly distributed, there will be phenomena such as unclear main branches, never clear branches, chaotic branches, overlapping congestion, poor ventilation and light transmission, uneven development of various parts, etc., which will inevitably affect normal growth and fruiting. It must be solved year by year by pruning.
(5) Number of fruiting branches and buds
Trees of different ages should have an appropriate proportion of fruiting branches and vegetative branches. There are many vegetative branches, few fruiting branches and few flower buds in the young tree stage. When pruning, cut less, put more flowers and leave more fruits. When there are too many fruiting branches and too few vegetative branches in adult trees, the consumption is greater than the accumulation, which is not conducive to stable production. When pruning, cut it short, retract it appropriately, and thin the fruit more. Old trees have many bearing branches, few vegetative branches and many flower buds, but the quality is poor, so they should be shrunk, cut and thinned more.