Winter jujube efficient cultivation key technology and storage preservation
Li Zhixin and others
Winter jujube is a kind of late ripening fresh food fruit, in Cangzhou, Hebei Province, generally ripe in early to mid-October, shaped like an apple, the average single fruit quality of 20 g, the peel is bright and ochre, the skin is thin and crisp, tender and juicy, sweet and fragrant, excellent quality, rich in nutrition, edible rate of 93.8%, has the name of "Hundred Fruit King". Winter jujube is mainly fresh food, its skin is thin and crisp, the use of appropriate preservation and storage technology to achieve winter jujube in the New Year's Day, Spring Festival listing, can greatly improve economic benefits.
1 Establishment of the park
Winter dates are more adaptable, but the most suitable soil is more fertile loam or sandy loam soil, and the winter dates produced are high yield and good quality. Winter jujube belongs to temperate deciduous fruit trees, and its growth and development require higher temperatures, so it germinates late and leaves fall earlier. The garden should choose a place with sufficient light, convenient watering, convenient transportation, and open terrain without pollution. Select robust, pest-free seedlings, with complete roots and a length of more than 20 cm, the grafting interface heals well, the height of the seedling is 120 to 150 cm, and the stem thickness reaches more than 1.2 cm at 5 cm above the graft site. Rootstocks can be selected with golden or sour dates, planted according to the row spacing of 3 m×4 m.
2 Soil fertilizer water management
In the winter jujube growing season, it is necessary to carry out medium tillage and weeding in time to keep the soil loose. After the fruit harvest, the autumn base fertilizer, mainly high-quality soil fertilizer, decomposed livestock and poultry manure, circle fertilizer and other organic fertilizers, young trees are applied organic fertilizer 25~50 kg per plant, with diammonium phosphate or urea 0.2~0.4 kg; the result trees are applied organic fertilizer 100~150 kg per plant, with diammonium phosphate or urea 0.5~1 kg, grass and tree ash 10 kg or potassium sulfate 1.5 kg. Root topdressing is applied twice a year, before germination, mainly fast-available nitrogen and phosphorus, young trees are applied 0.1-0.2 kg per plant, adult trees are applied 0.3-0.4 kg per plant, and nitrogen, phosphorus and potassium compound fertilizer is applied at the expansion stage of young fruits in early July, 0.4-0.5 kg per plant for young trees, and 0.6-1 kg per plant for adult trees. Topdressing should be applied in multiple holes outside the canopy projection at a depth of about 20 cm. Extra-root topdressing is carried out from late May to one month before fruit harvest, with foliar fertilization sprays every half a month or so. 0.3% urea can be sprayed before July and 0.3% potassium dihydrogen phosphate fertilizer can be sprayed later. Spraying urea and 0.2% borax mixture during flowering increases fruit set. Promote formula fertilization, so as to control nitrogen, stabilize phosphorus, increase potassium, advocate the application of microbial fertilizer, compound fertilizer, winter jujube special fertilizer, targeted use of micro-fertilizer. Apply nitrogen fertilizer in a timely and appropriate amount, and prohibit the use of chemical fertilizer 30 days before harvest to reduce its pollution of winter dates. Correct use of plant growth regulators. In the budding, flowering and fruit expansion stage of jujube trees, combined with topdressing irrigation once, to ensure the humidity of the jujube garden microclimate environment, reduce the damage of solar burn, water the frozen water before winter, pay attention to drainage in the rainy season, and prevent the jujube garden from accumulating water.
3 Trimming
Plastic pruning is the key technology of the production of densely planted jujube orchards, the main purpose is to maintain the balance of tree posture, keep the canopy ventilated and transparent, make the branches evenly distributed, and systematically renew and rejuvenate the fruiting branches to maintain the annual yield of the tree. Only by adopting a reasonable tree shape and pruning method can the annual harvest of the jujube garden be realized.
3.1 Pruning of trees of different ages
The tree shape is mainly free spindle shape, multi-main branch natural round head shape and small crown sparse layer shape. Young trees should pay attention to increasing the amount of branches, accelerating the formation of the canopy, and increasing early yield. The pruning of adult trees is mainly to stabilize yield, enhance tree potential, and improve fruit quality.
3.2 Trimming in different periods
Plastic pruning adopts the method of combining winter and summer and forming with trees. When pruning in winter, the young trees are in accordance with the structural requirements of the shape, and the 1-2 year old branches germinating on the backbone branches are retained as much as possible, and the method of carving buds, re-cutting and selecting the naturally germinated jujube heads is used in the appropriate parts of the trunk to cultivate the backbone branches; with the growth of the backbone branches, the same method of cultivating the backbone branches is used to promote the occurrence of jujube heads in the backbone branches, and the growth potential is controlled by heart picking, so that it is transformed into fruit branches; the jujube heads other than the backbone branches can be retained and utilized as a secondary branch first The pruning of the fruit tree should be planned to update and regenerate the fruit branch group, so as to maintain a long fruit life, mainly by treating the competing branches, cleaning the long branches, retracting the extension branches, removing over-dense branches, overlapping branches, thin and weak branches, juxtaposed branches, damaged branches and diseased branches, and improving the ventilation and light transmission conditions of the canopy. Summer pruning, mainly to wipe buds, remove too dense jujube heads, adjust the direction and opening angle of branches, jujube head topping, etc., can control the growth and angle of each new branch by adjusting, and improve the fruit set rate and fruit quality. In actual production, the northern, inner and lower parts of the same jujube tree will not suffer from sunburn hazards due to the shade of the branches, so the distribution of the resulting branches can be adjusted during pruning to reduce the damage of sunburn.
4 Flowering and fruiting period management
Jujube orchards with good fertility and water conditions and strong trees over 5 years old are opened at the beginning of jujube tree blooming. In early May, the management of new jujube heads sprouting between the backbone branches and fruiting branches began to be strengthened, and those who were not prepared to cultivate the extension branches and fruiting branches should be erased from the base. This is done in a planned sequence from early May to the end of July. For jujubes that are retained for cultivation branches and use the results, different degrees of plucking are carried out according to the strength of the tree and the size of the space. For upright-growing dates, pull them horizontally before flowering. If one side of the tree body lacks branches or partial crowns, the tree shape can be adjusted by pulling branches to increase the fruiting area; the beehive is placed in the jujube garden during the initial flowering period, which can effectively improve the fruit set rate and make the fruit set even. If the flowering period continues to be high temperature and drought, you can spray water on the foliar surface every 2 to 3 days during the full flowering period, generally 2 to 3 times, and the water spraying time is appropriate in the evening. Fertilizer spraying and hormones can be performed at the same time. During the flowering period, 10 to 15 mg/kg of gibberellin plus 0.3% to 0.5% urea solution can also be sprayed with 0.3% to 0.5% borax. Fruit thinning is usually done twice in mid-to-late June.
5 Pest control
5.1 Agricultural control
Strengthen the management of jujube gardens and maintain the robustness of trees. In autumn, the tree trunk can be tied to the grass to trap the overwintering pests, scrape the cracked bark and old bark at the trunk and branches before germination, remove dead branches and leaves, and eliminate overwintering diseases and insects.
5.2 Physical control
Artificially kill or use black lights, sexual attractants to trap peach heartworms, jujube stickworms and other adult insects, or apply an appropriate amount of sticky shellac to the trunk, which will be stuck when it is on the tree, can not continue to be harmful, and timely remove disease and insect leaves and jujube fruits, prune the branches of diseases and insects.
5.3 Biological control
Promote biological control technologies to reduce harm to natural predators. The use of natural enemies is an effective means of pest control, which can not only achieve the purpose of pest control, but also protect the ecological environment. The parasitic natural enemies of peach heartworms are the beetle-bellied cocoon bee and the Chinese tooth-legged wasp; grass aphids, red spiders and green blind bugs are natural enemies of pests such as aphids, red spiders and green blind bugs, and paying attention to protecting natural enemies in the winter jujube garden can play an effective role in the prevention and control of the above pests.
5.4 Chemical control
In early spring, orchards are sprayed with stone sulfur compound to reduce the base of overwintering diseases and insects. Pesticides for the control of pests and diseases should be selected from pesticides that are efficient, low-toxic, low-residue and safe for natural enemies. The use of highly toxic pesticides is prohibited, the resistance of diseases and insect pests is reduced, and the prevention and control effect is improved. The use of all pesticides is prohibited 20 days before harvest.
5.4.1 Green blind bugs
Green blind bugs mainly harm young buds, leaves, flower buds and young fruits, often causing leaf defects, falling flowers and fruits, and poor control will seriously affect the yield and quality of winter dates. The green blind bug is hidden during the day and harmed by the tree at night, and can spray the date tree and the weeds under the tree in the evening, and the effect is good. From mid-April to June, according to the degree of pest infestation in the jujube garden, timely drug control can be used, and it is possible to use drugs with low degree of natural enemy harm, such as Wanling and Lesben.
5.4.2 Peach heartworms
Peach small heartworms are infested by larvae borers, and the larvae are infested around the core, leaving insect droppings in the fruit, which seriously affects the yield and quality of winter dates. Mix 16% Lesben 2 kg or 48% octylthion emulsion 500 g with fine soil 15 to 25 kg and spread evenly on the ground around the trunk for surface control, and spray 20% permethrin emulsion 2,000 times solution during the initial incubation of the larvae.
5.4.3 Jujube armyworm
Jujube armyworm uses larvae to harm young shoots, leaves, buds and fruits, which can cause the victim fruit to fall early, and when it occurs severely, it will cause yield reduction or even harvest failure. It can be controlled by cypermethrin 5 000 to 10 000 times liquid or 4 000 to 6 000 times liquid plus 40% oxidized fruit 1 500 times liquid to mixed agent spray control.
5.4.4 Jujube gall mosquitoes
The larvae of the mosquitoes endanger the young leaves, buds and young fruits of the jujube, resulting in fewer flowers and affecting yields in severe cases. The young fruits turn yellow and fall off quickly after being affected, and during the infestation of jujube gall mosquitoes in May and June, spray 2 000 times the liquid of urea 3 at intervals of about 15 days, and spray 3 to 4 times.
6 Fruit harvesting and preservation
The jujube fruits stored and transported should be harvested at the right time, and the harvest is most suitable during the crisp ripening period, which is generally October 8 to 15 in Cangzhou, Hebei Province. It needs to be picked manually to ensure that each jujube fruit has a stalk and handle it gently to avoid damage.
After picking, the jujube fruit with mechanical damage, pests and diseases and deformities is removed. After grading, cleaning and disinfection, disinfection and blow drying after pre-cooling, pre-cooling room temperature is maintained at 4 ~ 5 °C, pre-cooling to make the jujube temperature cooled to 5 ~ 8 °C within 24 h. The time from harvest to pre-cooling should not exceed 12 h, and it is best to store with picking.
The storage method can be ordinary constant temperature storage, cellar storage, and modified atmosphere storage. When storing at ordinary constant temperature, the pre-chilled winter dates should be moved into the cold storage, generally with a capacity of 10 kg per box. When shipping, it is lightly loaded to prevent bruising. After packing, quickly seal and punch 8 to 10 holes with a diameter of 10 mm on the side of the bag. Cold storage temperature control -2 ~ 1 °C. When storing in the cellar, the pre-cooled winter dates are wrapped in polyethylene film bags and stored in the cellar. A chiller is installed in the cellar and the cellar temperature is controlled below 4 °C. When storing the modified atmosphere, the pre-cooled winter dates should be placed in the cold storage with the modified atmosphere equipment, and the cold storage requires the relative humidity of the air to be about 95%, the oxygen content to be about 3%, and the carbon dioxide content to be about 3%.