1. 1 Selection of planting site

Winter jujube is not strict with soil conditions. It can be planted in acid soil, alkaline soil, sandy soil or cohesive soil, but fertile sandy loam is the best. Therefore, we should choose a plot with open terrain, ventilation and no tall crops, and plant it in loose and fertile sandy loam with loose and deep soil layer (above 80 cm), good drainage, organic matter content higher than 1% and irrigation conditions. Avoid planting in wet and waterlogged plots.

1.2 planting time

It should be planted in spring and autumn, that is, between mid-April of that year1February, and after defoliation and before freezing in autumn. However, the dense planting of winter jujube trees should be planted after thawing in spring and before germination, and it should be planted later, because winter jujube trees need high temperature to take root and germinate. If planted too early in spring, the trunk will lose too much water, and the root system will be difficult to replenish, which will affect the survival. Therefore, it is best to plant in the middle and early April, with less water loss, quick rooting and high survival rate.

1.3 seedling selection

Two-year-old first-class strong seedlings were selected for planting. The height of strong seedlings should be about 1.5 m, the ground diameter should be more than 2 cm, the root width should be 25 ~ 30 cm, there are many lateral roots, there are no pests and diseases, the root system should be complete and developed, and strong secondary branches should be provided after the strong seedlings are shaped.

1.4 colonization

When planting, first soak the seedlings in clear water 10 h or so. In order to prevent planting with bacteria, 72 ppm of agricultural streptomycin was used 400 times before planting, and ABT rooting powder (50 ~100 ppm) was added or the roots were soaked with plant regulator Clandsang solution, which not only sterilized but also rooted, and then planted. The row spacing of dense plants is 2 m×3 m, and the row direction is parallel to the row edge of the planting area. Generally, the photosynthesis in the north-south direction is the best. Before planting, dig a planting pit with the length, width and depth of 80 cm, and place the topsoil and mature soil separately. When planting, first apply decaying fertile soil (50kg farmyard manure, phosphate fertilizer 1.5 kg and topsoil are evenly mixed to form fertile soil) to plant seedlings at a place 20 cm above the ground, then fill the topsoil and mature soil, step on it while backfilling, and pull it by hand to make the seedlings closely contact with the soil. After planting, irrigate with water, level the tree tray with soil, and then cover the root with 1 m 2 plastic film. The plastic film should be compacted with soil, with low middle and high edge, so as to increase rainwater storage, increase temperature and keep moisture. This can improve the survival rate and germination period by about 7 d, and promote the root growth of winter jujube. The plastic film should be removed before the rainy season.

2 fertilizer and water management

The winter jujube tree grows very vigorously, and the jujube head can germinate after planting for about 30 d and fixing the stem. After planting, according to the strength of the tree, apply organic fertilizer and compound fertilizer, mainly nitrogen fertilizer, with phosphorus and potassium fertilizer. In the year of planting, sole fertilizer was applied, so only water was needed in spring and summer. If the weather is dry, it is usually watered 1 time for 30 days to meet the water demand of trees. In the year of planting, the demand for phosphate fertilizer was high, so it is necessary to apply diammonium phosphate 0.5 kg· plant-1 in the middle of June in turn to promote root growth and tree growth. In order to supplement nutrition, spray 0.3～0.5 ppm urea or 0.3 ppm potassium dihydrogen phosphate solution on the leaves twice every 10 d to promote the maturity of branches and enhance their resistance. From the second year to the fifth year after planting, basal fertilizer is applied in autumn, mainly organic fertilizer (crop straw or animal manure fermented at high temperature can be selected), and deep ploughing 1 time at the end of September or the beginning of1October every year, and 50-60 kg plant-1 organic fertilizer and 2 kg· plant-/calcium magnesium phosphate fertilizer are applied. Organic fertilizer can make trees store nutrients, which is beneficial to the occurrence and growth of winter jujube roots, expand the distribution range of winter jujube roots and enhance the firmness of trees. According to the phenological characteristics of jujube trees, topdressing is generally carried out three times a year. For the first time, before germination in early spring (early April), available nitrogen and phosphorus were mainly used, but to control the amount of nitrogen, more application would cause the trees to grow vigorously. Therefore, the close planting garden should not exceed 0.25 kg· plant-1, and on the basis of properly controlling the amount of nitrogen fertilizer, 20 ~ 30 kg plant-1 should be added with organic fertilizer, so that the branches can be enriched and the excessive growth of jujube trees can be prevented. The second time before flowering (mid-to-late May), nitrogen fertilizer was mainly used, and the third time during the young fruit expansion period (late June-early July), compound fertilizer of nitrogen, phosphorus, potassium and trace elements should be applied. Young trees are mainly topdressing nitrogen fertilizer, and the mixing ratio of nitrogen, phosphorus and potassium is 1∶0.5∶0.6. Before flowering and in young fruit stage, the special compound fertilizer for fruit trees is topdressing 0.5 ~ 1 kg plant-1 each time. Every year, at the early flowering stage, the trees are covered with grass, the thickness is15 ~ 20 cm, and the soil is pressed after the grass is covered. Irrigation after fertilization and before covering grass every time, winter jujube needs a lot of water in the early growth stage, especially in flowering period and fruit growth period. Water shortage is easy to lead to flower and fruit dropping, and the water content is suitable, which is beneficial to pollination and fertilization and improves fruit setting rate. Generally, water is poured three times a year, that is, before germination, during the expansion period of young fruits and before freezing. Avoid irrigation in full bloom, irrigation in full bloom will cause a large number of flowers to fall, and the fruit setting rate will be significantly reduced. Drainage and flood prevention should be carried out in rainy season.

3 plastic pruning

The tree shape of winter jujube in dense planting garden is spindle-shaped, which has the advantages of fast formation, early fruiting period and light pruning. When the strong and old seedlings are planted in the same year, the dry height should be 0.4 ~ 0.65 m. If the soil conditions are good, the fixed dry height can be appropriately increased. The purpose of fixed stem is to control the height of the first layer of main branches, so as to cultivate high-yield tree types with low stem and short crown, and lay the foundation for high and stable yield of winter jujube trees. In the year of planting in the dense planting garden, the stem was fixed at a distance of 60 ~ 70 cm from the ground. After the stem was fixed, the first secondary branch under the cutting mouth was thinned and cut off from the base, and the jujube head was stimulated and the extended branch of the central stem was cultivated. The secondary branches within 20 ~ 40 cm of the plastic band are thick and short, thin and thin, and all the secondary branches below the plastic band are thinned. By the end of June, when the length of new shoots is about 60cm, 6 ~ 8 new shoots will be kept to promote their growth, and the angle will be adjusted to about 80 by branch pulling method. During winter pruning, 4 ~ 5 branches with good orientation are selected as backbone branches in the plastic band, and the rest are auxiliary branches. Both the extension branches of the central trunk and the extension branches of the backbone branches were cut at 40 ~ 50 cm, and1~ 3 jujube strands were cut to promote the growth of jujube heads, and the first secondary branch under the cut was cut off.

In the second year after planting, the first jujube branch under the cutting mouth is taken as the central trunk, and 4-5 branches with good orientation are selected as the backbone branches, and the backbone branches and auxiliary branches formed in the first year are pulled to droop after the jujube tree sprouts. From late May to early June, thinning the dense branches and the upright branches on the back should not affect the balance between light and vegetative and reproductive growth of the tree, and pinching the auxiliary branches. When cutting in winter, the jujube head branches that are too dense and too flourishing in the backbone branches and auxiliary branches should be thinned, and other winter cutting methods are the same as those in the first year. If the length of the extension branch of the central trunk can't meet the requirements of cultivating the second layer of main branches in the first year, it should be put slowly without cutting; In the next year, when the main buds of the central stem jujube head germinate and continue to extend and grow, and meet the requirements of the thickness and length of the extended branches of the central stem, the second layer of main branches will be cultivated, and so on.

In the third year after planting, from late May to early June, the plants with trunk diameter exceeding 4 cm and strong growth should be cut or girdled to control the growth and promote fruit setting. Other summer cutting measures are the same as those in the second year. During winter pruning, two main branches and1~ 2 auxiliary branches are selected on the extension branches of the central trunk, and other winter pruning measures are the same as in the second year.

In the fourth year after planting, after the jujube tree germinates, all the sprouting tillers on the tree are erased except the extension branches of the central trunk and backbone branches. Before flowering, the extension branches of the backbone branches are cored, the trunk is girdled, and the auxiliary branches and vigorous backbone branches are girdled. When cutting in winter, two backbone branches and1~ 2 auxiliary branches are selected, and the central branch is happy to fall. At this point, the height of the tree is about 2.5 m, the number of backbone branches is10 ~15, and the shaping and pruning of the dense planting tree is basically completed.

4 sitting on flowers and fruits

Winter jujube has a long flowering period and a large amount of flowers, but the flowers and fruits fall seriously. Therefore, flowering management should pay attention to three aspects. First, combine pest control and timely supplement foliar fertilizer. Foliage fertilizer can supplement plant trace elements, coordinate the balance between various elements and promote plant growth. Generally, foliar fertilizer should be supplemented 3-4 times during the flowering period of winter jujube, and the better foliar fertilizers are Hualebao 1 000 times solution, Saijin fertilizer 1 000 times solution and Jujube Fengbao 1 000 times solution. The second is to choose the right time to open the armor. The opening time of winter jujube should be 30 ~ 40% when winter jujube blooms. The premature fruit setting rate is low, which affects the yield; Too late, because of the short growth period, the single fruit weight and fruit quality decreased. The width of the nail opening is 0.8 ~1.2 cm, and the large trees should be wider and the small trees should be narrower. Third, the high temperature and dry weather during flowering will affect pollination and fertilization, and it is easy to cause burnt flowers. In case of drought at flowering stage, spray clean water on the leaves for 2-3 times after 5 pm every 2 days, and spray it for 3-5 times in severe drought. Jujube trees are sprayed with 0.2～0.3 ppm potassium dihydrogen phosphate 1 time at the interval of 7 ~10 d from the initial flowering stage to the young fruit stage.

In case of drought from the early flowering stage to the full flowering stage, jujube trees were sprayed with10 ~ 20mg l-1gibberellin (920) and 300mg l-1rare earth micro-fertilizer solution1~ 2 times. Spraying for the first time after nail opening can improve the fruit setting rate; Spraying jujube fruit for the second time after fruit setting can reduce the physiological fruit drop of jujube fruit. After the early high yield of winter jujube trees, the appropriate load should be determined according to the load capacity of the trees.

5 Control pests and diseases

The main diseases and pests that harm jujube trees are leaf diseases, jujube leaf spot defoliation and jujube rust; Fruit diseases such as jujube anthracnose and ring rot; Pests include jujube spider mite, jujube budqu, green blind stinkbug scale, jujube inchworm, red spider and brown spot moth.

Pests and diseases are mainly controlled by the following measures. After the jujube leaves fall, the fallen leaves, weeds, dead branches, diseased branches, diseased fruits, diseased fruits, etc. in the garden shall be thoroughly removed, and the old warped skin of winter jujube shall be scraped off for centralized destruction and incineration. Jujube trees are painted white in conditional jujube orchards, which plays a basic role in antifreeze, insect prevention and disease prevention. Turn the tree tray 1 time before winter and early spring, pick up the cocoon and pupa, and eliminate the pests such as jujube inchworm, green blind bug, peach bug, jujube gall midge and peach moth that overwinter in the soil. Before germination, the whole tree is sprayed with 3 ~ 5 degrees Pomesite Sulfur Mixture to prevent and control overwintering spider mites, scale insects and dry rot, so as to reduce the source of overwintering pests and diseases. Spraying 20 ppm fenpropathrin EC with 3 000 times solution from late April to early May to control pests such as stinkbug and Jujube Buqu. Spraying 2 ppm avermectin microcapsule suspension concentrate 1500 times or 20 ppm Mihuding EC 1 500 times from late May to early June to control jujube leaf mites and red spiders. 4 ~ 6 d after the jujube tree is opened, the nail opening is sprayed with 4 000 times of 10% cypermethrin EC, and sprayed every 7 ~ 1 0 d until the nail opening is completely healed. In mid-June, the mixture of 70 ppm mancozeb wettable powder 600 times and 50 ppm carbendazim wettable powder 800 times was sprayed to control jujube leaf spot defoliation. From mid-July, spray10 ~15 d at intervals, 1︰2︰200 lime double Bordeaux solution or 15 ppm triadimefon wettable powder 1 000 times solution or carbotrane 1 000 times solution.