Potted citrus can be shaped into a specific tree according to its growth and development characteristics and the preferences of growers. Common ones are natural round heads or natural semicircles; Tower shape or spindle shape with higher tree shape; Cylindrical shape suitable for hall or doorway display; The crown of the tree is low, and there are umbrellas extending regularly around the main branches; The trunk or main branch is flat and cliff-like; The longer trunk leans upward, such as the dragon shape of the arm and so on. No matter what kind of tree, we should strive for complete and compact branches and leaves, even and prominent fruit distribution, giving people natural beauty.
(2) Pruning
Citrus is usually pruned in winter and spring and twice in summer. Pruning in winter and spring can be carried out after fruit picking in areas without freezing damage and before spring tip picking; In areas threatened by freezing injury, it should be carried out in late spring. Summer pruning is mostly carried out before the growth of spring shoots stops and shoots sprout in late summer. The pruning period of varieties that bear fruit many times a year is often carried out after the fruit is picked.
(1) pruning before results.
The purpose of potted citrus is to cultivate the skeleton, form it quickly, and promote the neat and robust growth of branches before fruiting. It is often based on short cutting, supplemented by thinning, and the pruning amount is light.
Generally, single-bud cutting seedlings are about 10 cm short after the first branch matures to promote the growth of the main branch. When the main branch is mature, cut it short before pulling out new branches to promote branching. At the same time, it is necessary to strengthen the management of fertilizer and water during the growing season, strive to shoot more in that year, expand the canopy, and ensure that the last autumn shoot is timely and tidy.
In order to cultivate the big crown, it can be transferred to a big basin in autumn to continue cultivation 1 ~ 2 years later. How short should it be to promote growth, strengthen branches and expand crowns during the period?
② Pruning at fruiting stage.
Pruning at fruiting stage varies with citrus species and varieties. Ordinary citrus takes autumn shoots as the main fruiting mother branch, which blooms in the spring of the following year and matures in autumn and winter. Pruning should be based on the principle of "strengthening spring shoots, wiping summer shoots, cultivating autumn shoots and restraining winter shoots". The first branch of citrus has a great influence on the second branch. Generally, there are many spring shoots and few summer shoots. There are few summer shoots and many autumn shoots. In order to ensure strong autumn shoots, summer shoots must be controlled. The control measures are reducing topdressing and erasing summer buds in summer. After several times of bud smearing, the tree can be rich in nutrition and promote the growth and health of autumn shoots. The key to cultivating autumn shoots is to release them in time. It is easy for winter buds to develop too early, too late and grow poorly. Different regions should choose suitable bamboo shoot release date according to climatic conditions. The bamboo shoot release period in Guangdong is generally in early September. After the autumn shoots are released, the dense branches should be removed as soon as possible, leaving 20 cm for the long branches to pick the heart and promote their fullness and robustness.
All the branches of Four Seasons Orange can blossom and bear fruit in the same year. Its pruning principle is to promote the growth of neat and consistent fruiting mother branches and control the consistent flowering period and fruit maturity viewing period. In Guangdong, in order to enjoy fruits during the Spring Festival, from late May to early June, summer buds must sprout and buds must form. To this end, it is necessary to trim it three times. For the first time, before the spring shoots germinate, cut off the branches of grade 2 ~ 3, and the branches of weak trees can reach 1 grade, and generally leave 10 ~ 20 cm to promote the spring shoots to be strong. The second time, when the spring shoots are basically mature (about 60 days), cut off 15 ~ 20 cm to promote secondary branching. The third pruning is mainly to trim the top of the secondary branch slightly to promote flowering and tidy the crown. Prepare to promote flowering from late May to early June, 50 days after secondary branching.
(3) Flower promotion method
① Strengthen nutrition management.
Citrus has a large annual growth, more fruits and more fertilizers. Among them, the key periods that need more fertilizer are shoot promotion period, new shoot turning green period, flowering period, young fruit rapid expansion period and fertilizer and water recovery period after drought treatment. In order to promote flower bud differentiation, for citrus varieties that form flower buds in winter and spring, sufficient fertilizer can be applied in10 ~10 (9 ~ 65438+ 10 in the north) to keep the leaves dark green, and 0.5% urea and 0.5% urea can be sprayed in autumn and winter.
② Drought treatment
After the new shoots stop growing, moderate drought is beneficial to the formation of flower buds. Generally, water control in winter can promote flower bud differentiation of citrus varieties that bloom in spring; Timely water control in summer can promote the flowering and fruiting of Four Seasons Orange in the same year.
The key to drought control is to grasp the start time, duration and degree of water control. The start time of water control of Four Seasons Orange in summer should be when the leaves turn green and the branches are basically full, but it is appropriate to be immature, about 25 days after germination. At this time, touching the leaves with your hands does not stick to your hands or feel stiff. If the initial stage is too early, because of less nutrient accumulation, it is easy to fall leaves and the quality of flowers is poor; If it is too late, the leaf buds have already formed and it is difficult to transform them into flower buds. The water control time depends on the variety, weather and plant growth. For example, kumquat begins to form flower buds in 5-8 days. After water control, weak branches generally bloom earlier than strong branches, and the upper part of the same branch blooms earlier than the lower part. The degree of water control is appropriate when the two sides of the blade are rolled in but the midvein is not connected. At this time, the water content of the basin soil is about 64%, and when it is lower than 54.8%, the leaves often fall off due to excessive curling. In sunny summer, the leaves droop and curl the next day after water control, and then spray water on the leaves 2 ~ 3 times at noon and night every day, based on the principle of moistening the leaves without flowing. After spraying water, the leaves open again, and then lose water and curl. When the flower buds are formed, the water control can be stopped.
③ Ring cutting and bending branches.
Compared with drought treatment, ring cutting saves labor and trouble, is not affected by climate, has fewer leaves and shorter flower promotion time. But it only applies to Wang Shu and Wang Zhi. Under normal circumstances, the spring flowering seeds with autumn shoots as fruiting mother branches will be carried out in mid-June, 5438+February, and for branches with strong uprightness, it can also be carried out in September. Four seasons oranges are generally girdled in summer, and the optimal girdling time is 20 ~ 25 days according to the branch age of the mother branch. The number of ring cuts depends on the growth potential, generally one, and two when it is too prosperous. You can also cut the roots of big branches that grow very vigorously after the trunk is cut. After girdling, the leaves turn yellow about 15 days, and the purpose of promoting flowers can be achieved in 25 days.
Bending is to pull the upright and stout branches into a horizontal shape, which is mostly used on the flourishing trees and branches of flowering varieties such as bergamot. Guangdong bergamot is usually held in September, which can promote the flowering of autumn shoots that year.
(4) flower protection and fruit protection
Citrus is a fruit tree with large flowers and serious fruit drop. It is an important technical measure to control falling flowers and fruits and improve fruit setting rate.
(1) Cultivate strong tree potential.
The vigorous growth of trees is the basis of keeping flowers and fruits. Cultivating strong tree potential is mainly achieved through reasonable fertilizer and water measures and leaf protection and root protection. Specific measures are: preventing root injury; Supply fertilizer and water in time during greening, and spray fertilizer on the leaves of plants with abnormal greening; Prevent and control the harm of red spider and liriomyza sativae in time; Spraying10 ~15mg/l 2,4-drops in winter.
② Artificial pollination
For grapefruit and other varieties with low self-pollinated seed setting rate, it can be pollinated with brushes or directly with flowers in full bloom of pollinated trees, which can effectively improve the fruit setting rate.
③ Sparse flowers and fruits.
According to the normal leaf-fruit ratio of citrus fruit trees, based on the principle of weakening the retention strength and uniform distribution, thinning flowers and fruits is also an effective measure to improve the fruit setting rate. The normal leaf-fruit ratio of citrus fruit trees is: kumquat 6 ~10:1; Golden bullet 3 ~13:1; Wenzhou tangerine 24 ~ 28:1; 42 ~ 48 sweet oranges:1; 30 ~ 38: 1 Citrus is generally thinned in three times. Sparse too many and too dense buds at the first time to save nutrient consumption at flowering stage. The second time is when the small fruits grow to the size of peanuts, and the number of remaining fruits is about twice the predetermined number; Carry out the third fruit setting after physiological fruit dropping.
④ Shake the flowers.
When in full bloom, shake the crown, shake off petals and filaments, so that young fruits turn green and increase quickly when they see the sun.
⑤ Spray water to cool down.
In case of hot and muggy weather in flowering period, it is easy to cause a large number of flowers and fruits to fall off, so you can spray water on the crown in the evening to cool down.
⑥ Ring cutting
For the flourishing branches of flourishing trees, girdling can improve the fruit setting rate after the first fruit drop or when the small fruit drops properly for the second time.
⑦ Boron spraying at flowering stage
Spraying 0.2% borax and 0.5% urea at flowering stage is a common measure to protect flowers and fruits.
(8) Applying plant growth regulators.
2,4-D and gibberellin are commonly used plant growth regulators to protect citrus flowers and fruits. Specific usage:
Spraying 50 mg/l gibberellin or 5 ~ 10 mg/l 2,4-d plus 0.5% urea at withering stage is beneficial to fruit setting.
Spraying 0.5% urea and1.5 ~ 20 mg/l 2,4-d at the strong fruit stage can promote fruit development.
Spraying 20 mg/L 2,4-d before fruit ripening can prevent fruit from falling off.
Pet-name ruby bud removal
The growth of new shoots often competes with fruit development for nutrients, resulting in a large number of young fruits falling off. Therefore, the new shoots germinated after flowering should be pulled out in time when they are below 3 ~ 5 cm.
(5) Winter protection
It is very important to protect potted citrus in northern China in winter. The overwintering temperature is generally 0 ~ 12.5℃, and it is safe to control it at 5 ~ 10℃. Potted oranges can be kept indoors in autumn and winter. Try to create an environment with low temperature, high humidity, fresh air and good light when living in winter. Before leaving the house in spring, let the potted citrus gradually adapt to the external environment and move out after the late frost.