What are the characteristics of jujube growth?

Jujube belongs to the genus Zizyphus of Rhamnaceae, which has different characteristics from other deciduous fruit trees. For example, flower bud differentiation begins after germination in the same year, and is synchronized with the growth, bud formation, flowering and fruit setting of buds, leaves and new jujube heads. Fruit branches are deciduous fruit branches, which generally fall off with leaves after picking. Jujube has the characteristics of long flowering period, large flowering amount, serious flower and fruit dropping and extremely low fruit setting rate. In order to do a good job in the cultivation and management of jujube, it is necessary to understand the main organs and biological characteristics of jujube, which are briefly introduced as follows:

The root system of (1) root jujube can be divided into two types, namely stem source root and true root. Stem-derived roots are seedlings propagated by cutting branches and stem tissue culture, and the roots of seedlings produced by ramet method are stem-derived roots. Its characteristics are that the horizontal root system is more developed than the vertical root system, and its ability to extend around is strong, and its distribution range is 2 ~ 5 times that of the crown, which is conducive to increasing the absorption area of the plough layer. Horizontal roots grow well and can absorb nutrients in deeper soil, but the extension depth is far less than that of vertical roots of seedlings. The root system of Ziziphus jujuba is the root system of seedlings cultivated by Ziziphus jujuba seeds, and its vertical roots and horizontal roots are developed, but the vertical roots are more developed than the horizontal roots. According to the survey, the vertical root of1~1.8m is 0.5 ~1.5m long, accounting for 2% of the aboveground part. The root distribution of jujube is related to rootstock, propagation mode, tree age, soil texture and management, and is generally distributed in the soil layer of 15 ~ 30 cm. The root distribution of jujube trees by long-term ground fertilization is mostly in the soil layer of about 20 cm, and that of jujube trees by deep furrow fertilization is mostly in the soil layer of 40 ~ 60 cm. The root system has deep distribution, wide absorption range and strong drought and cold resistance, which is beneficial to the growth of trees. The horizontal distribution range of roots is generally concentrated in the crown projection range, accounting for about 70% of the total roots. The root system of jujube not only has the functions of absorbing and fixing soil and supporting trees on the ground, but also has the important functions of synthesizing nutrients and hormones, storing and transporting nutrients and water, and participating in metabolism. Its root system has the characteristics of tillering, so it is also an important reproductive organ. The root activity temperature of jujube is lower than that of the aboveground part, so the activity is earlier than that of the aboveground part, and the time to start growing varies with regions and years. In Cangzhou, root activity generally begins in late March, with a growth peak in July and August, and enters a dormant period after defoliation.

(2) The buds and buds of jujube are divided into main buds and auxiliary buds. The main bud, also called winter bud, is covered with scales and planted at the top of the first branch, jujube rootstock and the base of the second branch. The germination of main buds can generate jujube heads (developing branches), which are used to cultivate backbone branches and expand the crown; Jujube stocks (fruiting mother branches) can also be generated. The main buds at the top of jujube rootstock germinate every year, and the growth is very small. There are also main buds on the side of jujube trees, which are poorly developed and latent. Only after the aging of jujube rootstocks is stimulated, do they germinate into branched jujube rootstocks. Jujube heads can also sprout from jujube rootstocks, but the growth potential is weak, the life span is short and the utilization value is not high. When shaping young trees, the weight of secondary branches can be shortened (when the base diameter of secondary branches is 1.5 ~ 2 cm), which can stimulate the formation of new jujube tree heads and cultivate them into backbone branches with relatively horizontal angles. Secondary buds are naked buds, also called summer buds, attached to the primary branches. They germinated in the same year to form secondary branches or detached secondary branches, and the secondary branches and secondary buds on jujube rootstocks produced detached fruiting branches, that is, hanging dates. Some main buds can be dormant for many years, becoming hidden buds or dormant buds, with a long life. After stimulation, they can germinate and produce robust jujube heads, which is beneficial to the renewal of fruiting base branches and backbone branches. Adventitious buds are easy to occur in the trunk, base of main branches or mechanical damage of jujube trees, which are mostly developed from ray parenchyma cells and can generate jujube heads. These characteristics are the reasons why jujube trees have a long life and can still bear normal fruits for more than 100 years.

(3) The young branches of jujube trees generally grow vigorously, with upright tree posture and strong dryness, grow moderately after maturity, open tree posture, and reduce the germination and branching ability of branches. Some varieties still grow vigorously after reaching maturity. Jujube branches can be divided into three categories, namely jujube head, jujube stock and jujube hanging. Jujube head: The development branch developed from the main bud of jujube is the main branch that constitutes the skeleton or fruit unit branch of the tree, which is equivalent to the so-called development branch on other fruit trees such as apples and pears. Jujube head is the general name of primary branch and secondary branch, and each jujube head has 6 ~ 13 secondary branches. The secondary branch is the fruiting branch formed by the secondary buds of each node of jujube head, which is also called fruiting branch group. Without terminal buds, the tip will wither in the next spring. The fruiting branch group composed of jujube head and secondary branches is also called fruiting base branch. Jujube rootstock: it is a fruit-bearing branch with minimal growth, and it can also be regarded as a shortened jujube head, which is the morphological variation of jujube head from vigorous growth to fruiting. The jujube rootstock germinates from the main bud, grows slowly, and grows coarsely with the increase of branch age. The top of jujube rootstock has a main bud and scales around it. Jujube rootstocks are mainly planted on secondary branches for more than two years. Jujube strands can also be formed at the top and base of the first branch of jujube. Each jujube anvil can produce 3 ~ 20 jujube hangers. When natural disasters and artificial jujube pendants are broken, new jujube pendants can germinate and bear fruit that year, which is also the reason why jujube trees have strong disaster resistance. The life span of jujube stocks is very long, which can reach more than 20 years. It is observed that the 3-7-year-old jujube rootstock has the strongest seed-bearing ability, and it is weakened year by year after 10, so it should be updated in time. Of course, the economic life of jujube rootstocks is closely related to varieties and cultivation management. Orchards with high management level will have a long life, otherwise they will be short. There are differences between varieties. For example, jujube trees with a year or two bear the best fruit. Jujube hanging: that is, fruit branches, also known as falling fruit branches. It is mainly formed by secondary buds on jujube rootstock, and dates can also be hung on the nodes of the first and second branches of the year. With the germination of jujube trees, jujube hanging began to elongate, set leaves and differentiated with flower buds to form flower buds, which blossomed and bore fruit. When the fruit is ripe, it will generally fall off with the fallen leaves after autumn, and some jujube pendants with high lignification are not easy to fall off. The number of jujube hanging is closely related to the length and variety, the nutritional level, age, position and management level of the tree. If the head of jujube tree is re-pitted, lignified or semi-lignified jujube hanging can be produced at the base, and the fruiting ability is obviously improved. Jujube cranes are generally 8 ~ 30 cm long, 10 ~ 18 knots. Hanging on the same jujube, 4 ~ 8 leaves are the largest, and 3 ~ 7 nodes are the most fruitful.

(4) Leaves are important organs for photosynthesis, gas exchange and transpiration. Jujube trees have alternate leaves, which are oblong, rectangular and lanceolate, generally 3-8 cm long and 2-5 cm wide. The leaves are leathery, shiny, thick in wax layer, hairless, with obtuse tips, serrated leaves, some sparse and thick, green leaves and yellowish green petioles. When the average temperature drops to 65438 05℃, it falls off with the jujube crane.

(5) Flowers and fruits Jujube flowers are planted in the axils of jujube leaves. Generally, there are 3 ~ 8 flowers in a leaf axil, and a single inflorescence can be produced due to insufficient nutrition. Its differentiation characteristics are differentiation in the same year, multiple differentiation and differentiation with growth. Single flower differentiation is fast and short, and the flower bud differentiation of the whole tree lasts for a long time, which can reach about 2 months. The flower bud differentiation of jujube is closely related to the storage nutrition and environmental conditions of the tree. Generally affected by nutrition and temperature, the leaves at the base and top nodes of jujube hanging are small, the flower bud differentiation is slow, the flower quality is relatively poor, the fruit setting rate and fruit quality are low, especially in drought or dry hot wind, it is easy to burn and drop flowers. The leaves in the middle node are large, the flower bud differentiation is complete and full, and the fruiting ability is significantly enhanced. The flowering time of northern jujube is generally from early June to early July, with different regions, different varieties, different accumulated temperatures in different years and different flowering periods. When the spring is dry and the temperature is high, the flowering period is early and short, and when the spring temperature is low, especially when the flowering period is rainy and the temperature is low, the flowering period is late and long. It is observed that the jujube trees in the yard are ahead of the jujube trees in the field, and the young trees are ahead of the old trees. The flowering sequence is the earliest in the periphery of the crown, and the flower buds that differentiate first generally open first. The central flower in an inflorescence blooms first, followed by 1 class flower, 2-class flower and multi-class flower. There are two types of jujube flowering: night bud splitting type and day bud splitting type, but pollination and pollination are both in the daytime, which has no adverse effect on pollination.

(6) Pollinated jujube is a typical insect-borne flower, and it has an aromatic honey juice dish. Most jujube trees are self-pollinated (few varieties need pollinated trees because of their low self-pollination rate), while cross-pollination has a high fruit-setting rate, so it is advisable to plant more than two varieties in jujube orchard. It should be strongly advocated to release bees at flowering stage and complete pollination. The fruit setting rate was the highest on the day of flowering, and then decreased gradually. The pollination and pollen germination of jujube flowers are closely related to the environment, hormones and nutritional level. Low temperature, drought, strong wind and rainy weather are all unfavorable to pollination and fruit setting. The optimum temperature for pollen germination is 22 ~ 26℃, and the relative humidity is 70% ~ 80%, which is lower than 20℃ or higher than 38℃, and the relative humidity is lower than 60%, which is not conducive to pollen germination. This is also the reason why spraying water, 92 _ and micro-fertilizer at flowering stage can improve the fruit setting rate. Jujube in full bloom has good quality and high fruit setting rate. The fruit setting rate of flowers before the initial and final flowering stages is low, and the fruit quality is also poor. In production, technical measures should be taken to improve the fruit setting rate in full bloom to ensure the yield and quality of jujube.

The content of this article comes from: Natural Resources Protection by China Agricultural Publishing House.