Construction and management technology of greenhouse of Zhendong No.2 winter jujube

Construction and Management Techniques of Greenhouse for Winter Jujube Cultivars of Zhandong No. 2

"Zhandong 2" is a new jujube variety with good quality and late ripeness. It has beautiful fruit shape, rich nutrition and excellent quality. However,"Zhendong 2" is easy to crack fruit before harvest, fruit is sensitive to external stimuli, easy to produce fruit rust, and has poor ability to resist wind, rain, hail, fog, frost, snow and low temperature. The practice proves that adopting spring-warm greenhouse cultivation can effectively solve these problems, and at the same time can properly mature and market ahead of time, and improve economic benefits. Therefore, the construction and management techniques of "Zhendong 2" in greenhouse were discussed to achieve high quality and high efficiency, and to promote the large-scale production of this fine variety.

1 Construction of greenhouse

1.1 the choice of location

Winter jujube greenhouse should choose flat terrain, convenient transportation, good drainage and irrigation conditions of the plot, garden neat, wide rows, short age, short trees, fertile soil garden. In order to ensure the firmness of the greenhouse, try to avoid building the greenhouse in the low-lying easy to accumulate water, high ridge tuyere.

1.2 Determination of greenhouse orientation

Considering the convenience of planting, wind resistance and light transmittance, the construction of greenhouse is most beneficial to management. Because the strong winds above Grade 7 in Binzhou area of Shandong Province, the main producing area of "Zhandong 2", are mostly southwest wind, northwest wind or north-northeast wind, in order to reduce the windward side, increase the wind resistance coefficient of greenhouse and increase the lighting area, it is appropriate to adopt the north-south direction [3].

1.3 Main structure of greenhouse

1.3.1 Selection of materials

Bamboo pole, cement purlin or galvanized steel pipe can be selected for column; bamboo pole or galvanized steel pipe can be selected for skeleton.

(1) Cost

The greenhouse cost of the whole bamboo pole structure is about 5000 yuan, the greenhouse cost of the cement purlin column and bamboo pole framework is about 7000 yuan, the greenhouse cost of the cement purlin column and galvanized steel pipe framework is about 10000 yuan, and the greenhouse cost of the whole galvanized steel pipe structure is 15000~25000 yuan.

(2) Characteristics

Full bamboo pole structure, economical, simple structure, small construction difficulty, less investment, but not durable, poor wind resistance; full galvanized steel pipe structure is durable, beautiful and generous, the best lighting, the strongest wind resistance, the largest construction space, both conducive to farming operations, but also conducive to the improvement of winter jujube quality, but a large one-time investment. Cement purlin column combined with galvanized steel pipe framework greenhouse, moderate cost, and durable, long service life, recommended use.

1.3.2 Shelter structure

(1) Height of shed

The side column should not be lower than the height of the tree, generally 2~2.5m. The middle column is 1~1.5m higher than the side column, generally 3.5~ 4m, so that the distance between the treetops and the top of the shed is kept at least 1m, so as to prevent the sun burning disease caused by too high temperature under the film.

(2) Scaffolding span

Generally, the span of the structure should be 12~15m, and too large a span will cause the slope of the greenhouse bow surface to decrease or the side column to decrease, which is not conducive to lighting and wind protection. The span is too small, the temperature fluctuation in the shed is large, and the construction management cost increases.

(3) Length of scaffolding

Depending on the size of the block, 60~80m is appropriate. Column and anchor line had better be buried along the tree row, convenient fertilization, spraying, picking and other field management.

(4) Roof radian

According to solar radiation angle, 30° has the highest transmittance, the fastest temperature rise in spring, the lowest wind pressure coefficient and the strongest roof.

1.3.3 Cover film

It has been proved by practice for many years that winter mulching in spring shed is an effective way to prevent cold injury of "Zhandong 2", and it is also different from winter jujube in ordinary greenhouse (mulching in February). Therefore, the cover time of "Zhandong No.2" should be from the end of November to the beginning of December (before freezing), and it can be carried out if there is no rain, snow or cold weather in the latest week.

The shed film should be selected with high transmittance and durable drip-free film. It is recommended to use nano light-converting grouting film (with many functions such as long service life, good light transmission, heat preservation, cooling, light conversion, diffuse scattering and reduction of diseases and insect pests). The shed film should be three or four pieces. In addition to the skirt film that must be kept above 1m from the ground, it is best to set 0.8~1m ventilation skylight on the roof of the shed to facilitate the early stage of raising the ground temperature and the later stage of ventilation and cooling in the shed. The shed surface is the part of the greenhouse structure that is more easily damaged, mainly in the corner, edge and ridge of the shed surface. The anti-wear reinforcement is emphasized when covering the film.

2. Shed temperature regulation and ventilation management

Because the flower and fruit of "zhendong 2" are sensitive to external stimuli, the most important factors in the whole growth period of "zhendong 2" are temperature control and ventilation management. Most of the problems such as fewer buds, difficulty in fruit setting and low yield are due to the high temperature and excessive ventilation in the shed. Greenhouse temperature control should grasp the basic principle of "early insulation and late cooling, raising temperature without hesitation", which is divided into the following six stages.

2.1 film freezing period

From the cover of the shed to the middle of February of the following year, only the top film is kept in this period to prevent freezing rain and freezing snow. The skirt film is opened for ventilation for a long time to control the temperature to prevent the temperature from being too high.

2.2 germination period

In the last ten days of February, the main method is to seal the shed for heat preservation, and close the skirt film to make the ground temperature increase rapidly (in order to effectively increase the ground temperature, plastic film can be added). During the day, the temperature should be controlled at about 30℃, the highest temperature should be controlled below 35℃, and the night temperature should be above 10℃. If the temperature is too high during the day, the top wind can be passed, and the side wind should be blocked as much as possible. When passing the wind, pay attention to the vents to stay between the trees and avoid the top of the tree. This period lasts about 15 days until budding begins.

2.3 germination stage

Germination stage refers to the stage from emergence of buds to orderly budding. The temperature should be lower than that in the early stage during the day, with the highest temperature controlled below 30℃ and the night temperature above 10℃. Ventilation in this period should be dominated by top wind, less side wind, and good ground temperature should be maintained.

2.4 flower bud differentiation stage

Flower bud differentiation period namely jujube hanging growth period, also called bud formation period. The flower bud differentiation period is from bud tidiness to anthesis, during which the main task is to keep warm at night and cool down during the day. During the day, the temperature should be controlled at about 30℃, and the highest temperature should be controlled below 35℃. The maximum number of flowers and the most plump flowers should be controlled at 18~30℃. If the temperature is too high, it will affect the bud differentiation, and there will be no buds, few buds and buds falling. Ventilation and cooling is the key to this period. In order to reduce the noon temperature, early ventilation is required, which can pass both top wind and side wind.

2.5 fruit setting stage

The optimum temperature for fruit setting is 25~30℃, the highest temperature in daytime is controlled within 35℃, and fruit setting activity stops above 35℃. During this period, the temperature outside the shed has been high, and the temperature in the shed rises rapidly. Attention should be paid to ventilation and cooling during the day and proper heat preservation at night. Ventilation in this period should be early and timely. Remember not to wait until the temperature in the shed rises to the required temperature before ventilation; avoid excessive ventilation, resulting in excessive temperature difference, easy to fall flowers, scorched leaves, difficult fruit setting, etc.

2.6 After fruiting to before harvest

At this stage, the outside temperature is already high, so it is necessary to strengthen the ventilation of the shed body, prevent the temperature inside the shed from being too high, keep the temperature inside the shed and the temperature outside the shed small difference, and promote the normal growth of jujube fruit.

3 Cultural management

3.1 fertilization

A large amount of fertilizer and water requirement is one of the characteristics of "Zhendong 2". In the whole growth period, it should absorb a large amount of nutrients and water from the soil to meet the needs of flowers and fruits, otherwise the fruit setting rate will be low, the fruit will become smaller and the fruit will shrink seriously in the later stage. The basic requirements of fertilization are: mainly organic fertilizer, combined with the use of nitrogen, phosphorus and potassium compound fertilizer and trace element fertilizer, appropriate supplement of rare element fertilizer.

Basal fertilizer should be applied after harvest in autumn and before defoliation, or before germination in early spring. It is suggested to apply decomposed farm manure (or finished organic fertilizer)+ nitrogen, phosphorus and potassium compound fertilizer + medium trace element fertilizer, and appropriate compound microbial fertilizer can also be added. Finally, mix all kinds of fertilizers with soil and apply them to the soil. Furrows 50~60cm from the trunk and 40cm deep and wide are recommended.

Topdressing from the middle of June, every 20 days topdressing high-quality water-soluble fertilizer, continuous topdressing 3 times, the first two times should be selected low nitrogen phosphorus high potassium fertilizer, the third time selected low nitrogen phosphorus high potassium fertilizer. In the middle and late September, after the winter jujube is picked, the water-soluble fertilizer containing the same amount of three elements is applied once, and the topdressing method adopts multi-point application [4].

3.2 watering

Before covering the shed, combine with autumn base fertilizer irrigation once, after covering the shed generally do not need to irrigate. If the drought is serious, drip irrigation, infiltration irrigation, border irrigation and other methods can be adopted for small irrigation, avoid flood irrigation, resulting in excessive humidity in the shed. The greenhouse cultivation of "Zhandong 2" should be combined with the application of water and fertilizer integration technology to keep the soil and air humidity stable in the greenhouse and prevent sunburn, fruit shrinkage and fruit drop caused by drought in the later stage of jujube growth.

3.3 training and pruning

Different from common winter jujube,"zhandong 2" usually adopts high grafting and head replacement to establish garden because of its very low survival rate. Moreover,"zhandong 2" has strong preference for light, so its shaping method determines the selection and retention of grafted maternal branches by open heart shape or small crown sparse layer shape, and then orients the grafted new branches by binding to cultivate ideal tree shape. For the convenience of management, the tree height can be appropriately controlled, and it is appropriate to be about 1m lower than the shed film. Because the branch group of "Zhendong 2" is easy to age, the pruning method is mainly thinning branches and slowly releasing, thinning the over-dense branches at the base, changing the vertical growth direction of the branches with growth space by supporting, pulling, separating and twisting, and increasing the number of branches by using the effective growth space. In combination with summer shears, nutrient consumption is controlled and tree structure is stabilized by means of bud wiping and core picking [5].

3.4 flower and fruit protection

Protecting flowers and fruits is the most important cultivation technique measure in the production of "Zhandong 2", which mainly refers to girdling, spraying plant regulators and thinning fruits on the basis of summer pruning such as bud wiping, branch pulling and core picking in the early stage. When the jujube blossoms in the shed are 30%(early flowering), the trunk or main branch of the tree should be girdled, and the girdling width must be determined according to different age and different tree vigor. Spraying "920" and 0.2% boric acid for 1~2 times 2~ 3 days after girdling could significantly increase the fruit setting rate. From the beginning of July, artificial fruit thinning can be carried out on "Zhendong No.2", which should be determined according to the tree strength, age and management level of the garden, so as to create conditions for high quality and high efficiency.

3.5 pest control

Compared with common winter jujube,"Zhandong 2" has no special susceptible diseases and insect pests. Due to the high temperature in greenhouse, attention should be paid to the prevention and control of red spiders in early stage. 34% spirodiclofen suspension agent should be sprayed evenly at 4000~5000 times in early May, and sticky insect glue should be applied to trunk for control. Because the fruit of "Zhandong No. 2" is more sensitive to chemicals, the dosage and frequency of application are reduced compared with ordinary Zhanhua winter jujube, and all growth regulators are prohibited, otherwise it will affect the quality and cause fruit color, and reduce the appearance. The disease and insect pest control of "Zhendong 2" should start with healthy cultivation, cultivate tree vigor and improve tree resistance to diseases and insect pests.

3.6 Disaster prevention

In the spring to do a good job in the cold work at the same time, we should strengthen the greenhouse winter jujube disaster prevention. Date farmers must strengthen the top film without affecting ventilation, especially in the last month before the maturity of "Zhandong No.2", patrol and strengthen the shed from time to time to prevent wind, rain, hail, fog, frost and other disastrous weather after fruit setting. Otherwise, it will cause serious economic losses when encountering disasters such as film breakage and shed lifting.

In short, greenhouse cultivation is the most suitable cultivation method for producing high-grade fruit of "Zhendong 2", which not only adapts to the physiological characteristics of "Zhendong 2", but also meets the market demand, and is suitable for large-scale popularization.