Planting and maintenance methods of jujube trees;
(1) Temperature Jujube is a warm-loving tree species, which needs higher temperature during its growth and development. Jujube trees cultivated in the north germinate late and shed leaves early. When the spring temperature reaches 13- 15℃ (around mid-April in Cangzhou), jujube buds begin to germinate. When the temperature reaches 17- 18℃, the jujube tree branches, bears fruit, grows, leaves spread out and flower buds differentiate. When the temperature reaches 19℃, flower buds appear, and the daily average temperature reaches 20-. The suitable temperature for pollen germination is 22-26℃, and when it is lower than 20℃ or higher than 38℃, the pollen germination rate is significantly reduced. The suitable temperature for fruit growth and development is 24-27℃. When the temperature is low, the fruit grows slowly, with less dry matter and poor quality. The suitable temperature for fruit ripening is18-22 ′ c, so the temperature in flowering and fruiting period is an important limiting factor for jujube planting area. When the temperature drops to 15℃ in autumn, the leaves turn yellow and begin to fall off, and all the leaves fall off at the initial box stage. The ability to resist extreme temperatures is very strong in winter, with a low temperature of -34℃ in hibernation and a short-term high temperature of 50CC in summer.
The daily average fruit-setting temperature is an important factor in jujube regional cultivation, which can be divided into wide-temperature type (the daily average fruit-setting temperature is above 265,438 0℃, such as Daguazhao, Banzao and Chai Lin Lizao, which are widely cultivated) and normal-temperature type (the daily average fruit-setting temperature is not lower than 22℃, such as Jinsixiaozao, Junzao and Dali Zhao Yuan). ). Different varieties have different tolerance to extreme high and low temperatures, different temperatures needed in each growth period, different requirements for soil environment, and different disease resistance and fruit cracking resistance. The characteristics of these varieties should be fully considered when introducing them, so as not to cause losses to production.
(2) Humidity jujube is a tree species with strong early resistance and waterlogging tolerance, and it has a wide range of adaptation to humidity, with annual precipitation of 100-
1200mm, and the annual precipitation is 400-700mm. The minimum annual rainfall in Cangzhou is insufficient 100.
Mm, site height 1 160mm, all can grow and bear fruit normally, and the jujube orchard will not die after more than 30 days of water accumulation. Different growth periods of jujube trees require different humidity. The flowering period needs high humidity, and the relative humidity of 70%-85% is beneficial to pollination, fertilization and fruit setting. If this period is too dry and the relative humidity is lower than 40%, it will affect pollen germination and pollen tube elongation, resulting in poor pollination and fertilization, serious flower and fruit drop and decreased yield. The phenomenon of "burnt flowers" is caused by dry air and low relative humidity. If there is too much rainfall in the flowering period, especially if the flowering period is rainy and cold, it is not conducive to pollination, the pollen is easy to burst, it can not germinate normally, and the fruit setting rate will also decrease. In the later stage of fruit growth, it is required to have less rain and sunny weather. High temperature during the day, low temperature at night and large temperature difference between day and night are beneficial to sugar accumulation and fruit coloring. If there is too much and too frequent rainfall, it will affect the growth and nutrient accumulation of fruit, aggravate fruit diseases such as fruit cracking and pulp rot, and reduce the quality of jujube fruit. Soil moisture will affect the water balance in trees and the growth and development of various organs. The field water holding capacity of soil is about 70%, which is beneficial to the growth of jujube trees. When the water content of 30 cm soil layer is 5%, jujube seedlings will wither temporarily. When the soil moisture content is 3%, it will wither permanently. Too much water, poor soil ventilation, one root will be affected by suffocation, and long-term water accumulation will also cause jujube tree death.
(3) Illumination and sunlight are the basis of all living things, providing inexhaustible energy and realizing energy transformation through plants. Only under the action of light, carbon dioxide absorbed in the air and water absorbed in the soil (including water absorbed by leaves) are transformed into minerals in chloroplasts of leaves, and oxygen is released, and light energy is transformed into chemical energy, thus completing energy conversion. Appropriate light can promote the growth and differentiation of plant somatic cells, control cell division and elongation, maintain normal photosynthesis, and be beneficial to the accumulation of dry matter of trees and the healthy growth of various organs. For example, the differentiation and formation of flower buds, quality, fruit setting rate, fruit growth, coloring, sugar and vitamin C are all directly related to light. Moreover, insufficient light will also affect the growth of roots, because the nutrients needed for root growth mainly depend on photosynthetic products on the ground, and root growth will affect the growth and development of all parts on the ground, and photosynthesis is also inseparable from the water and minerals absorbed by roots.
At present, some winter jujube orchards are densely planted in order to achieve the goal of early fruiting. However, due to improper management, the jujube orchard was closed, and the canopy ventilation and light transmission were poor, which led to the increase of invalid leaf area and the decrease of leaf productivity, which led to the weak tree potential and the poor growth of jujube head, secondary branches and jujube hanging. As a result, the fruit setting rate is low, the yield is low, the fruit quality is poor, the branches in the inner chamber die, the fruit parts move out, and the pests and diseases are serious. Therefore, the winter jujube orchard must be properly reshaped through winter pruning and summer pruning.
The population structure and tree structure are too dense, and the effective leaf area increases, which makes the tree strong and achieves the goal of high quality and high yield of winter jujube.
(4) Soil Jujube generally has low requirements for soil and strong adaptability. It is a kind of tree species with strong resistance to hard lumps and salt and alkali.
In the range of soil pH5.5-8.2, the salt content is not higher than that in coastal areas. It can grow on 0.3% soil. (pH is table.
The pH value of soil solution, where the pH value of soil solution is less than 7, is acidic. The smaller the pH value, the stronger the acidity, and the soil is soluble.
The pH value of the solution is equal to 7, which is neutral, and greater than 7 is alkaline. The greater the pH value, the stronger the alkalinity). Both plain wasteland and hilly wasteland can be planted.
In particular, the Regulations on the Protection of Basic Farmland issued by the State Council 1998 stipulates that it is forbidden to occupy basic farmland to develop forestry and fruit industry. The excellent characteristics of jujube, such as barren tolerance and saline-alkali tolerance, are of special significance in the adjustment of agricultural industry and the increase of farmers' income in the future. Winter jujube and golden jujube planted in coastal saline-alkali land in Cangzhou area not only grow well, but also produce famous brand golden jujube and winter jujube with good quality. There are also famous jujube production in mountain counties such as Zanhuang Jujube in Hebei and Lvliang in Fuping, Shanxi, such as Zanhuang Mansion, Fuping Slope Jujube: Lvliang Muzao, etc. Nevertheless, planting jujube trees on plots with fertile soil and good environmental conditions can make jujube trees grow well, grow vigorously, bear fruit early, have high yield, good fruit quality and high economic benefits even if the production cost is low. Therefore, before planting jujube trees, high-quality soil must be prepared to create good soil and environmental conditions for the growth of jujube trees.
(5) wind. Breeze and wind are beneficial to the growth of jujube trees, can promote gas exchange to maintain the normal concentration of carbon dioxide and oxygen in jujube forests, regulate the temperature and humidity of air, promote transpiration, and are beneficial to the growth, flowering, pollination and fruiting of jujube trees. Strong wind and dry wind are extremely unfavorable to the growth and development of jujube trees. Although jujube trees are very resistant to wind in dormancy, strong wind in germination will change the growth state of shoots, inhibit normal growth and even break branches. Strong winds, especially dry and hot winds, will scorch flowers and buds or fail to pollinate them, reducing the fruit setting rate. When the fruit is blown by the wind in the late growth stage and before maturity, it will drop or reduce the quality of the fruit. In order to reduce the adverse effects of wind on the growth of jujube trees, we should avoid the tuyere when choosing a garden, plan to plant shelterbelts before building the garden, and take technical measures such as spraying water during flowering to improve the microclimate in the field and create a more suitable ecological environment for the growth and development of jujube trees.