Protected cultivation can artificially control environmental conditions, especially temperature conditions, and plants can grow all year round, which can completely change the seasonality and periodicity of growth and development under natural conditions, providing the possibility for changing the harvest time of fruit trees. However, in order to change the harvest time of fruits and supply them to the market on demand, it is necessary to artificially control and promote flower bud differentiation, break the dormancy of fruit trees, scientifically control trees and realize on-demand production.

1. Promote flower bud differentiation Under natural conditions, flower bud differentiation of fruit trees generally begins after the end of June and is completed before April of the following year. Different fruit tree varieties began to differentiate in different periods and completed differentiation in different periods. In order to change the harvest period of fruit trees under natural conditions (generally earlier), it is necessary to differentiate flower buds early and shorten their differentiation period. At present, the main methods commonly used are:

(1) High temperature and long sunshine. According to research, high temperature and long sunshine are beneficial to promote flower bud differentiation of fruit trees. Under the condition of facilities, the heat preservation began in the end of 10 of 65438, which was two months earlier than the growth period of open cultivation, and the flower bud differentiation could be greatly advanced.

But there are exceptions, for example, strawberry flower bud differentiation needs low temperature and short sunshine. Under 8 hours of sunshine, 10 ~ 20℃ can differentiate flower buds, but above 30℃, flower buds will not differentiate regardless of the length of sunshine. According to the research, strawberry takes the shortest time to enter the flower bud under the condition of 8 hours sunshine and 65438 07℃, and goes into dormancy below 5℃, and the flower bud will not differentiate. Therefore, in order to promote the differentiation of strawberry flower buds, low temperature and dark treatment or seedling raising in alpine regions can be adopted.

(2) inhibiting the growth of new buds. The vigorous growth of new shoots will affect the differentiation of flower buds, so the growth of new shoots should be inhibited when flower buds begin to differentiate. The methods of inhibition include coring, girdling, twisting branches and chemical treatment, but chemical treatment is the most convenient and effective. Commonly used chemicals include CCC, B9 and PP333. At present, PP333 is widely used in production in China. This chemical can inhibit the growth of peach, cherry, grape, apple and other fruit trees and promote the formation of flower buds. There are two application methods: foliar spraying and soil application. The concentration of foliar spraying is generally 1000 ~ 3000 μ g/g, and the application time is generally after flowering. The general dosage of soil application is 1 ~ 10g per plant, depending on the size of the tree, and it is generally applied to the periphery of the crown in spring.

(3) Nitrogen control. Excessive nitrogen will lead to vigorous vegetative growth and inhibit or delay the differentiation of flower buds. In order to promote flower bud differentiation, it is necessary to control the excessive application of nitrogen fertilizer during flower bud differentiation, especially for young trees, and the application of nitrogen fertilizer should be as early as possible before flower bud differentiation, but it is necessary for some old trees and weak trees to apply nitrogen fertilizer even during flower bud differentiation.

2. Dormant fruit trees have a dormant period in the annual cycle development. It is generally believed that fruit trees enter the dormant period after defoliation until they germinate and bloom in the next spring, which is called the dormant period. In fact, the dormancy of fruit trees is not after falling leaves, but before falling leaves. For example, grapes enter dormancy in the first half of September, and enter deep dormancy before defoliation at 5438+1mid-October in June.

After the fruit tree enters the dormancy period, the period when it is still dormant even under the condition of suitable temperature is called natural dormancy period. After natural dormancy is released, due to inappropriate external conditions, it is called forced dormancy. In protected cultivation, the first problem to be solved in protected cultivation is to correctly judge the period of releasing dormancy and scientifically use the measures to release dormancy.

To release the dormancy of fruit trees, it is necessary to accumulate a certain low temperature below 7.2℃ (low temperature demand). Different kinds and varieties of fruit trees have different requirements for breaking dormancy at low temperature (Table 2 1- 1).

Table 2 1- 1 Low temperature requirements for several deciduous fruit trees to break dormancy

There are also some differences in the demand for low temperature among different varieties of the same tree species. Because fruit trees have different low-temperature requirements for releasing dormancy, the period of releasing dormancy is also different, which determines the period of heat preservation. Low temperature demand is insufficient, and heat preservation is started. Although it can grow, the germination rate is low, the germination is irregular and the growth effect is poor.

In recent years, with the development of protected cultivation techniques, people have taken some measures to artificially break dormancy and achieved certain results. At present, the commonly used methods are temperature treatment, leaf picking and chemical treatment.

Low temperature treatment has been widely used in strawberry protected cultivation, that is, after flower bud differentiation, the seedlings are dug up, bundled and placed in a cold storage at 0 ~ 3℃ with a humidity of 80%. The treatment time can be determined according to the low temperature required for the variety to break dormancy.

High temperature treatment has obvious effect on breaking grape bud dormancy. According to research, in greenhouse cultivation, when the temperature is above 30℃, it is easy to break dormancy.

Picking leaves can also break dormancy. In Taiwan Province Province, China, dormant buds of grapes, peaches and pears germinate by picking leaves, which can make grapes bloom three times a year and harvest three times, while peaches and pears bloom twice a year and harvest twice.

Chemical treatment to break dormancy has been successful at home and abroad. Chemicals used are plant growth regulators, such as lime nitrogen, ethephon, chloroethanol and gibberellin. Lime nitrogen is widely used.

Lime nitrogen can break the dormancy of fruit trees such as grapes, peaches and plums. The research shows that lime nitrogen is a good defoliant.

Gibberellin is also considered to be effective in breaking dormancy. However, it has been proved that it is difficult to break dormancy only by gibberellin, which can only replace part of low temperature treatment. Only when the low temperature is insufficient, spraying gibberellin will be effective.

(2) Control of tree body

The investment in facility cultivation is large, so it should be able to receive economic benefits in a short time. Therefore, we should aim at dwarfing, close planting and early fruiting. However, under the facility conditions, due to high temperature, high humidity, long growth period and weak light, the trees grow vigorously and the branches are easy to grow white, resulting in closed crown, weak branch growth and poor flower bud differentiation. Therefore, corresponding technical measures must be taken to control the growth of crown.

1. The planting density protection field has a large one-time investment in fruit tree cultivation, and fruit trees are crops with late fruit and slow effect. How to make them bear fruit early, bear fruit early and take effect early is an important subject of protected fruit tree cultivation. Research and practice have proved that close planting is one of the important ways to bear fruit and yield early. Close planting can make full use of limited space, increase the number of fruit branches per unit volume and increase early yield as soon as possible.

The lighting in the facility is poor, and the planting density should not be too high without experience. Joe can master 150 ~ 300 rootstocks and 200 ~ 400 vines, and take corresponding pruning methods and crown control measures. According to experience, 300 ~ 400 nectarines and apricots are planted at 667m, plums are planted at 667m 150 ~ 200, cherries are planted at 80 ~1000, grapes are planted at 667m, and strawberries are planted at 667m, 800 ~ 1000.

2. Crown-controlled pot culture is an effective method to control root growth. In the first spring of protected cultivation, 1 year-old grafted seedlings should not be planted directly in greenhouse, but in pots, so that the roots of fruit trees are strictly confined in pots with fixed volume, which changes the deep and wide natural distribution, thus limiting the growth of roots and further limiting the elongation and thickening of new shoots on the upper part.

Generally speaking, vegetarian flowerpots can be used for potted plants. The flowerpot is 35 ~ 40 cm in diameter and is filled with nutrient soil. Nutrient soil is mixed with decomposed manure or garden soil with mushroom substrate, and the ratio is about 1∶5. The bottom hole of the basin is covered with broken tiles, so that it can be ventilated without leakage of soil. First put the mixed nutrient soil into 1/3, and then plant the seedlings. When planting trees, the roots should be elongated, closely connected with the soil, and then filled with nutritious soil. The degree of nutrient soil filling should be that the interface is exposed to the soil surface, and it is filled to 80% full, and there is a water outlet on it to facilitate watering. The planting period should be before germination in spring.

3. The chemical crown-controlled paclobutrazol (PP333) can obviously inhibit the growth of new shoots, promote the formation of flower buds and improve the fruit-setting rate and yield on many fruit trees, whether it is sprayed or applied in soil. However, due to different tree species, varieties, application methods, periods and concentrations, the effects are also different. The application in peach is the most obvious. The application of paclobutrazol can reduce the growth of new shoots by 20% ~ 50% and increase the yield by more than 20%, and it is early-maturing, and has no effect on the size and quality of fruits. It can obviously inhibit the growth of grape, cherry, apple, pear and other tree species and promote their fruits. During the use period, it is appropriate to apply soil at the end of 10 in autumn; The effect of foliar spraying in mid-May in spring is better. The application concentration is generally 3 ~ 4.5g per plant, and the foliar spraying concentration is 1500 ~ 2000g.

Step 4 reshape and trim

(1) plastic. The principle of high-density plastic surgery should be short stem, short crown and few main branches. The commonly used trees are natural and happy, Y-shaped, and special pruning methods used in grassland orchards.

① Natural happy shape. The trunk is 30 ~ 50 cm high, and the top of the trunk is evenly distributed with three main branches, each of which extends at a 45-degree angle. Two lateral branches are left on each main branch, and the opening angle is 60 ~ 70. And cultivate large, medium and small fruit branches on the main side branches.

The conventional shaping method is: when the grafted seedlings are cutted in the winter of the first year after fixation, three main branches scattered on the trunk are selected, and the cutting length is generally about 40 cm. In the winter of the second year of planting, at the top of the three main branches, two lateral branches with suitable directions are left on each main branch, the opening angle of the lateral branches is about 70, and the cutting length depends on the growth potential.

Rapid plastic surgery can also be performed under well-managed conditions. When the grafted seedlings grow to 60 cm in spring and the secondary buds grow to 40 cm for the first time, the secondary buds core, and the primary and secondary buds core for the third time in early August. Pull, twist and divide the branches of non-main branches and side branches. This can shorten the plastic surgery time for one year. Under good fertilization conditions, flower buds can be formed that year.

In the case of potted crown control, there is no need to force the tree shape, and the main purpose is to bear fruit early.

②Y-shape, that is, a happy shape with only two main branches. It is the main tree used in protected cultivation at present. The stem was fixed at 60 cm in the year of planting. In the first year of winter planting, two branches with opposite directions and extending inward were selected for cutting, the angle was about 40, and the cutting length was 40 ~ 50 cm. The remaining branches can be slowly released according to the tree species, pulled, twisted and chopped, and cultivated into different types of fruiting branches. When cutting in the winter of the following year, lateral branches of 2-3 years are selected on each of the two main branches, and the angle of the lateral branches is about 60, and the cutting length depends on the branches and growth conditions. Cultivate large, medium and small fruit branches on the main branches and side branches.

③ Nerve plexus. The trunk is short or has no trunk. 4 ~ 5 main branches can be left on the trunk. The initial plastic method is to leave 2 ~ 3 lateral branches on the main branch. At present, some people only leave 3 ~ 5 main trunk branches on the trunk, and fruiting branches occur on the trunk branches. The pruning method is: under the condition of facilities, after harvesting in May, all the tree crowns are cut off, leaving only 3-5 short branches with a length of 5- 10 cm on the trunk. These short branches grow new branches from June to 10, forming COVID-19, and the new branches can form flower buds in the same year. There are few branches formed in the first year after topping, and then they increase year by year.

The above three shaping methods are suitable for stone fruit trees. The specific method can be determined according to planting density, tree species characteristics and cultivation management conditions.

(2) pruning.

(1) winter pruning. The key is to keep the tree. For branches that grow too high and the crown diameter is too long, they should be retracted to control the crown and keep the appropriate size. For branches that are too big and dense, they should be thinned. For developing branches and fruiting branches with moderate development, they can be truncated to different degrees according to the length of branches.

② Pruning in summer. The main purpose of pruning should be to control the vigorous growth of branches, solve the problem of ventilation and light transmission, and promote flower bud differentiation. The methods adopted are as follows: first, pulling branches, increasing the angle of branches, and inhibiting the vigorous growth of branches; The second is twisted branches, that is, when the upright branches or flourishing branches with space grow to lignification in the lower part, they are twisted downward by hand at a position 5 cm away from the base, so that the xylem and epidermis are injured, and the twisted branches are separated from the base as long as they are not broken; Third, pinching, that is, picking the growth points or tender shoots of new shoots that have not stopped growing in the same year, forcing the new shoots to temporarily stop growing, so as to increase the accumulation of nutrients, reduce the concentration of auxin at the top, and increase the supply of cytokinins, so as to facilitate the accumulation of nutrients in the lower branches and promote the differentiation of flower buds; The fourth is thinning. For the parts with too many branches and covered branches, the branches should be thinned to facilitate ventilation and light transmission, save nutrients and promote flower bud differentiation.