First, the role of shaping and pruning
Scientific pruning of citrus plants has four main functions: one is to cultivate trees with early fruit and high and stable yield; The second is to improve canopy ventilation and light transmission conditions and improve photosynthetic efficiency; Third, adjust the distribution of nutrients to promote high quality and high yield; The fourth is to reduce pests and diseases and rejuvenate trees.
Second, the principles and requirements of plastic trimming
Pruning citrus plants must be handled flexibly according to the characteristics of various types and varieties, tree age and other factors. Usually, citrus plants are pruned scientifically according to the purpose of early fruiting, high and stable yield and high quality. Special note: Citrus plants can only be pruned under the premise of strengthening fertilizer and water management and pest control in orchards, otherwise the expected purpose will not be achieved.
(A) plastic principles and requirements
The main object of plastic technology is to plant 1 to 5-year-old citrus plants. One is low stem and short crown. Trees with short stems and short crowns need less nutrients, shorten the distance between roots and leaves, and facilitate nutrient transportation. Generally, it is required that after three years of planting citrus seedlings, each plant will basically form an early fruit and high yield crown through shaping and pruning. Within 65,438+0 years of planting citrus seedlings, the trunk with a height of 65,438+05-20 cm should be left off the ground, the trunk height of citrus and grapefruit should be 20 cm, and the trunk height of broad-skinned citrus should be 65,438+05 cm. In the year of planting, the shaping zone of citrus plants is generally determined within the range of 10- 15 cm above the height of the left trunk, and three branches with staggered directions and a spacing of about 3 cm are left to cultivate the main branches. In the second year of planting, 2 ~ 3 secondary branches are cultivated on each main branch. In the third year of planting, 2 ~ 3 lateral branches are cultivated on each auxiliary main branch. Then the branches are cultivated year by year to form fruiting mother branches, and the crown with early fruiting and high yield is cultivated. The second is to form a compact natural circular main shape or a circular simple tree shape. Generally, grafted citrus seedlings have fewer big branches, more branchlets and wider main branch angles after planting. Small branches, quick modeling, saving tree nutrients, symmetrical skeleton and good lighting performance. There are many branchlets, many leaves, many synthetic nutrients, many mother branches and high single yield.
(2) Pruning principles and requirements
By pruning the crown of citrus plants, the layers are clear and the surface is wavy, so that the internal light of the crown is sufficient, the green layer of leaves is thick, the effective volume is large, and the fruit can be produced inside, outside and above. Therefore, it is generally necessary to trim mainly with light scissors to protect leaves and thin branches. First, young trees are mainly shaped, supplemented by light cutting. Small trees have few leaves. In addition to cultivating the main branches and auxiliary branches, other branches should be lightly cut or not cut, and as many leaves as possible should be left, so as to make full use of leaves to make nutrients and expand the crown. Second, the pruning of adult fruit trees is mainly light pruning, supplemented by moderate heavy pruning. Generally, sparse and thin new shoots or hybrid 1-2-year-old new shoots are used, which should not be pruned again; For a single tree with dark crown and poor ventilation and light transmission in the inner room, a proper amount of "skylight" should be used to sparse large branches (perennial) to improve the ventilation and light transmission performance in the inner room of the crown. Third, old and weak trees should be cut down again to promote new shoots or update the crown. Short scissors are used to stimulate weak buds to produce strong new buds. Generally, the heavier the degree of short cutting, the more obvious the stimulation effect. Usually, a part of the annual branches of/kloc-0 is cut short and used for weak trees or "small old trees" to stimulate the bud germination under the incision and produce strong new shoots; Retraction is to cut off the perennial branches or backbone branches of aging trees at the late stage of fruiting, so as to stimulate the emergence of strong new branches and thus update the crown.