Cultivation techniques of Hongdan crisp jujube

Cultivation techniques of Hongdan crisp jujube

Hongdan crisp jujube is a variety of Zaozhuang crisp jujube found in the jujube garden of Songshanwan Village, Xinzhuang Town, Fei County in 1998. the fruit is oval, the single fruit weighs 16.5 to 22.5 grams, the pericarp is thin and crisp, the white maturity is light green, and the flower face is ripe. Ochre red accounts for 70% and 80% of the fruit. The meat is crisp, sweet and juicy, with a sweet taste. The stone is very small, the sugar accumulates early, and the content of soluble solids (mass fraction) is 26.3% (figure 1). The variety has strong high yield, a small amount of fruit can be seen when it is planted in the same year, all the fruits can be seen in the second year, and the average yield per plant in the third year is 5.5-8.5 kg. By the end of 2017, it had grown to more than 10,000 mu in Feixian County alone, with an annual output of more than 3 million kilograms.

1 colonization

The planting period of jujube seedlings is from defoliation to pre-freezing and thawing to germination period. A fixed planting hole of 0.8 m × 0.8 m is dug during planting. 20-25 kg mature soil fertilizer and 0.5 kg special compound fertilizer for fruit trees are applied to each plant during backfilling. After backfilling, it must be watered and covered with plastic film.

2 fixed dry

The height of the fixed stem is 70cm to 80cm, and the fixed stem is too low, which is easy to droop and drag the ground after the main branch bears fruit, resulting in difficulties in management under the tree and decline in the quality of jujube fruit; if the fixed stem is too high, the growth of jujube head is small, it is not easy to rapidly shape, and it is delayed to enter the fruiting period; if the seedling quality is not good, two buds can be cut short, and a vigorous jujube head is selected to re-cultivate the trunk after budding, and pick out the heart when the seedling height is more than 80cm.

3 shaping and pruning

Hongdan crisp jujube has medium branching force and small tree body, so it is suitable to use free spindle or cylindrical shape in production. The row spacing of free-spindle plant is (2-3) m × (3-4) m, and that of cylindrical plant is (1-2) m × (2-3) m. The free spindle tree has a height of 2.5 to 3.0 meters and a dry height of 60 to 80 centimeters. The tree has a total of 810 main branches, and the thickness of the main branches does not exceed 1 of the central trunk, spirally arranged on the central trunk. The lowest first main branch is preferably in the southeast or southwest direction. The distance between the two adjacent main branches is 20 cm 30 cm. The distance between the two main branches in the same direction is not less than 100 cm. It is no longer equipped with lateral branches, and the fruiting branches are planted directly on the main branches. The opening angle of the lower main branch is 80 °~ 90 °, and that of the upper main branch is 70 °~ 80 °. The height of the cylindrical tree is about 2 meters. 10-12 branches of the whole tree are directly planted on the main branches, the lower branches are strong and the lower branches are weak, and they are evenly distributed horizontally on the central trunk. During plastic shaping, 4-6 secondary branches are required to be retained more than 60 cm above the ground. When the secondary branches grow to more than 6 nodes, the jujube heads to be issued in the second year grow 6-8 secondary branches, and when the secondary branches are more than 6 nodes, they are coring. During plastic surgery, the upright and growth advantage of the central stem should be maintained, and attention should be paid to controlling the growth of jujube head. If necessary, the jujube head can be cut short or coring properly to prevent the inner chamber from being empty. The fruiting branch group of jujube tree has the strongest fruiting ability in 3-8 years, and attention should be paid to timely updating (figure 2).

Fig. 2 shaping and pruning of jujube

4 soil fertilizer and water management

4.1 Base fertilizer

Every year from fruit harvest to defoliation, each jujube tree digs 3-4 holes and applies 10-15 kg of rotten organic fertilizer or 3-4 kg of biological bacterial fertilizer and 0.3 kg of nitrogen fertilizer.

4.2 topdressing

In pre-flowering, young fruit stage and fruit expansion stage, compound fertilizer was applied to each fruit tree with 4-6 holes, about 0.25 kg each time, in order to promote jujube tree to blossom more, blossom well and promote fruit expansion.

4.3 Water management

Each fertilization should be combined with watering, which is conducive to the transformation and absorption of fertilizer and the expansion of the fruit. The growing season should be watered according to the dry weather.

4.4 soil management

Because jujube orchards are mostly built in mountains, the soil layer is barren, so it is necessary to deep turn and expand holes in the soil every year to increase the thickness of the soil layer. During the growing season, the soil is covered with natural grass or biological mulch between rows. Grass or biological mulching can adjust the temperature and humidity of orchard, improve soil aggregate structure, increase the content of soil organic matter, prevent soil erosion and reduce jujube fruit cracking. However, it should be noted that when growing grass, malignant weeds such as clover and gray vegetables should be removed in time, benign weeds such as Magnolia mandshurica and dog tail should be retained, nitrogen fertilizer should be added appropriately (2.5-5kg per mu), and the stubble should be cut when the grass is 40 cm high. The height of stubble is 15-20 cm (figure 3).

Fig. 3 Grass growing in jujube garden

5 measures to promote flowers and management of flowers and fruits

5.1 pulling branches and supporting branches

It is generally carried out in May May, so that the branches are evenly distributed, the canopy is well ventilated and transparent, the tree potential is relaxed, and the flower and fruit are promoted.

5.2 wiping buds

From late April to early July, the newly germinated jujube buds should be erased from the base as soon as possible, and the jujube hanging at the base should be retained so as to save nutrients and be beneficial to tree growth and development, flowering and fruit setting.

5.3 pick the heart

Coring is an effective measure to control vegetative growth and save nutrients. Coring can reduce flower and fruit drop and significantly increase fruit setting rate. The new jujube head, secondary branch and jujube hanging were picked out from sprouting leaves to the middle of July to restrain the excessive growth of jujube head.

5.4 Open armour

Jujube nail opening is also called ring peeling, which aims to prevent the organic matter produced in the aboveground part from being transported to the root, which can improve the fruit setting rate of jujube tree. Nail opening should be carried out on more than 5-year-old trees, and the best time is in full bloom in early June, and the girdling site should be 30 cm away from the ground, smooth and scar-free. The width of the girdling should not exceed 1x10 of the trunk thickness, and the xylem should not be deeply injured. The girdling should choose sunny and windless weather. One week after opening, the peeling should be smeared with 150-fold solution of thiazuron 3 to control the peeling pest and promote the healing of the peeling 20-30 days after peeling.

5.5 spraying water at flowering stage

The flowering stage of jujube is often dry, and the air relative humidity is low, which is disadvantageous to pollen germination, thus affecting fertilization and fruit setting. Therefore, in the case of dry weather during the flowering period, spraying clear water evenly on the tree crown with a sprayer can increase the fruit setting rate by more than twice. The suitable time for spraying water is after 5: 00 p.m. At this time, spraying water can stagger the time of spreading powder in jujube flowers, and keep it moist for a long time, which is conducive to pollen germination. Generally spray for 2 days, once a day.

5.6 releasing bees at flowering stage

Releasing bees in jujube orchard can improve the rate of cross-pollination, so it can increase the rate of fruit setting. Most varieties of jujube can be self-pollinated and fruited. However, cross-pollination can significantly increase the fruit setting rate. Releasing bees at flowering stage in jujube orchard can fully pollinate jujube flowers and increase fruit setting rate by more than 68%. And the nearer the jujube tree to the beehive, the better the effect.

5.7 foliar spraying

Foliar fertilizer spraying with 0.3% (mass fraction) potassium dihydrogen phosphate solution, amino acid, 0.1% boric acid and so on during flowering and young fruit stage can not only reduce the occurrence of flower and fruit drop, but also improve fruit setting rate and single fruit quality. improve fruit quality.

5.8 spraying plant growth regulators and trace elements

Spraying plant growth regulators and trace elements can increase the fruit setting rate. At present, the commonly used plant growth regulators are gibberellin, 2mai 4murD, sodium naphthalene acetate and so on, among which gibberellin is widely used (commonly known as "920"). Gibberellin can promote the pollen germination of jujube and stimulate the fruiting of unpollinated jujube flowers. Spraying 10: 15 mg / kg gibberellin at full bloom can increase the fruit setting rate by more than 70%. Trace elements such as boron, zinc and iron can also promote fruit setting rate and yield. Spraying 0.2%-0.3% boric acid or borax at flowering stage can increase the fruit setting rate, because trace boron can significantly increase the pollen germination rate.

(6) Disease and pest control

The main diseases and insect pests of Hongdan crisp jujube are jujube fruit shrinkage disease, black rot, jujube rust, jujube madness, green bug bug, jujube step, jujube armyworm, tortoise wax scale, red spider, peach heart borer, leafhopper and so on.

The prevention and control of jujube diseases and insect pests should give priority to prevention, strengthen measurement and forecast, and pay attention to the comprehensive control of agricultural physics and chemistry. Agricultural physical control: scraping bark during dormancy, cleaning dead branches and leaves, deeply burying tree plates (10 cm), overwintering pests in frozen soil, binding 10 cm wide plastic sheeting at the base of tree trunks in the first ten days of April and applying waste oil to prevent jujube moths from going up the tree; trapping jujube armyworm adults with black light, hanging peach sex attractants in the middle of June, binding grass at the base of tree trunks in early September to trap pests, removing the grass and burning it after falling leaves. Chemical control: green bug bug, jujube bug, jujube armyworm, tortoise wax scale, red spider, peach heart borer, leafhopper and other pests can be sprinkled with 3% phoxim granules and hoe (peach small) according to the occurrence period. The trees can choose 10% imidacloprid 3000 times, 1.8% avermectin 4000 times, 22.4% spirothyl ethyl ester 4000 times, 5% acarate 1500 times, 25% thiazine 2000 times, pyrethroids and other mixed alternative control. Diseases such as jujube fruit shrinkage, black rot and jujube rust can be alternately treated with fungicides such as 72% agricultural streptomycin 3000-fold solution and 10% difenoconazole 1500-fold solution, 43% tebuconazole 3000-fold solution and 5% pyrazolyl ester 1000-fold solution. The pathogen of jujube mad disease is mycoplastid, which is mainly transmitted by grafting, root splitting and orange band quasi-rhomboid leafhopper, Chinese quasi-rhomboid leafhopper, red flash leafhopper, concave edge rhomboid leafhopper and other insects. After the jujube tree is infected, the existing medicament treatment effect is not ideal, mainly to prevent, the main measures are to cultivate disease-free seedlings, planting garden away from Platycladus orientalis (Platycladus orientalis is the main overwintering breeding place), timely eradication of diseased branches and so on.