L. Pruning principle: "ventilation and light transmission are less pests and diseases, and three-dimensional fruit yield is high." Good ventilation can reduce the temperature and humidity in the park and reduce the occurrence of many pests and diseases; It can make the leaves thicker, the branches stronger, strengthen the tree potential, and enhance the disease and insect resistance of the tree itself. On this basis, ensure a reasonable number of branches and leaves and their distribution, so that the upper and lower parts will bear fruit inside and outside, and the yield will increase. 2. Pruning method "long-term planning, comprehensive arrangement; Shape with the tree, pruning by skill; Balanced tree potential, clear master and slave; Light cutting is the mainstay, combining light and heavy. " (1) when pruning, keep the proper proportion of fruiting branches and vegetative branches, promote the balance between growth and fruiting, and cut in small years to promote renewal and rejuvenation; Cut small crops every year, try to make them bear fruit, and keep increasing production on the basis of high quality, stable yield and high yield. (2) For orchards of middle age and above, pruning should not be too demanding, no matter whether the tree shape is standard or not, it is mainly to ensure the reasonable density of branches and leaves, and let them bear fruit as much as possible. On the same tree, pruning of annual branches should be light and sparse; The pruning of young branches should be heavy, mainly with short cut retraction. (3) When pruning, take the trunk as the center, and through retraction, short cutting and throwing, make the extension distance of branches and the amount of branches and leaves coordinated and symmetrical, and the results will not be off-center, which is beneficial to the balanced development of roots; When pruning, the main branches should not be left too much, so as not to occupy space, block the sun, and easily empty the chamber, which is unfavorable for three-dimensional results and long-term high yield. (4) The fruit-bearing ability is strong, and the pruning should be light, subject to the leaves. The pruning amount should not exceed 1/4 in winter and 1/15 in summer. 3. The leaf curtain requires that "the small space is not empty, the outer space is not empty, and the flowers and the sun shine on it." The number and distribution of leaf curtain, that is, leaves, should be moderate in number, well-distributed, tight inside and not empty outside, with no space around, and even light can be seen on the branches and leaves of the inner chamber, so as to achieve the effect of ventilation, light transmission and three-dimensional results. Generally, satsuma oranges need 25 ~ 3 leaves per fruit; Jincheng needs 45 ~ 5 leaves per fruit; Navel orange needs 6 ~ 8 leaves per fruit; Ponkan needs 8 ~ 9 leaves per fruit. 4. Pruning branches in summer, twisting tips, more hands and less knives, quick forming and early results. Summer pruning is based on winter pruning, and functional leaves should be kept as much as possible. Adjust the orientation and angle of branches and promote the differentiation of branches and flower buds mainly through operations such as pulling branches, coring, twisting shoots, smearing buds, fruits and vegetables. 5. Open the light path. "Open the skylight and pull down the pile, and see the light in the bore." When pruning, part of the tight branches shall be thinned out, and 1 ~ 3 branches shall be selected to leave piles in the proper parts of the inner chamber for retraction, and the "skylight" shall be opened. After receiving light, the hidden bud of the stump is easy to germinate, and the core is picked up in time after germination, so that the inner cavity has both branches and light, creating conditions for three-dimensional results.