What are the requirements for pepper cultivation in plastic greenhouse?

The general requirements for pepper cultivation in plastic greenhouse are:

(1) Strong warming: The temperature in the greenhouse is often low in spring and autumn, which is not conducive to plant growth. Therefore, the greenhouse must have a strong temperature rise, that is, the greenhouse heats up early and quickly during the day. (2) Good thermal insulation performance: First, the greenhouse should maintain a certain internal space to enhance its thermal insulation capacity; Second, the greenhouse should be built in the leeward and sunny place, where there is no wind shield, and the windproof wall should be set on the windward side of the greenhouse to play a windproof role. (3) Good lighting performance requires that the greenhouse be covered with a non-dripping film or a semi-dripping film with good light transmission performance, instead of an ordinary dripping film. (4) The uniform distribution of light in the greenhouse requires that the width of the greenhouse be appropriate, but not too wide. The suitable width is about 8 ~ 14m. (5) Greenhouse vents with convenient temperature management should be set reasonably, with reasonable number of top and middle vents, moderate positions and easy opening and closing. (6) The greenhouse is highly suitable for operation and management. The middle height is 2 ~ 2.5 meters, and the side height is more than 1 meter.

402. What are the main types of plastic greenhouses used in pepper production at present? What are their characteristics?

At present, there are many kinds of plastic greenhouses used in pepper production. To sum up, there are mainly the following points:

(1) bamboo arch greenhouse This greenhouse uses precast cement columns with a cross section of 8 ~ 12× 8 ~ 12 (cm) as columns, and thick bamboo poles with a diameter greater than 8 cm as arches. The cost is relatively low, and it is the most widely used plastic arch shed in rural areas.

The main disadvantages of this large arch shed are: first, the bamboo arch has a short service life and needs to be replaced regularly; Second, the number of columns in the shed is relatively large, and the ground illumination is not good, which is not conducive to soil preparation and mechanized management in the shed. In order to reduce the number of columns in the shed, this shed mostly adopts the structure of "two arches and one column", which is also called "hanging beam hanging column", as shown in Figure 28.

Fig. 28 Structure of plastic arch shed 1 "two arches and one column". Short column 2. Column three. Pull rod 4. Arch (2) steel arch shed This shed is mainly made of φ 8 ~ 16 mm round steel and 1.27 cm or 2.54 cm steel pipe. , made of double chord arch circular steel beam arch. In order to save steel, generally, the upper chord of steel beam adopts round steel or steel tube with slightly larger specifications, and the lower chord adopts round steel or steel tube with smaller specifications. The spacing between the upper chord and the lower chord is 20 ~ 30 cm, and the middle is connected by φ 8 ~ 10 mm round steel. Most steel beams are processed into plane beams, and when the steel specification is too small or the greenhouse span is relatively large, the single arch load is large, it is processed into triangular beams. The spacing between steel beams and arches is generally 1 ~ 1.5m, and the frame is connected by φ 10 ~ 14mm round steel.

Steel arch shed has the advantages of firm structure, long service life, no or few columns in the shed, excellent environment and convenient installation of automatic management equipment on the shed frame, which is the development direction of modern plastic arch shed. The main disadvantages of this greenhouse are relatively high cost and strict design and construction requirements. In addition, the steel frame itself is easy to damage the plastic film and shorten the service life of the film. (3) Greenhouse with pipeline assembly structure This greenhouse is made of thin-walled galvanized steel pipes or rigid plastic pipes with certain specifications and assembled, connected or fixed with corresponding accessories. The scaffolding in greenhouse is produced by the factory, with reasonable structural design and easy handling and installation. There are many specifications and models of greenhouse, and there is a large choice, which is the mainstream of greenhouse development in the future. (4) Composite Arched Greenhouse The arch of this greenhouse adopts glass fiber reinforced cement prefabricated structure or fly ash composite prefabricated structure, which is generally a column-free structure and is the mainstream of modern greenhouse development.

This kind of shed frame is generally arc structure, with rectangular cross section, smooth upper part and tight shed film to reduce wear; High bending and compressive strength; Light weight; High and low temperature resistance, no deformation after long-term use at -40 ~ 100℃; The shed film has no rust and burn defects, which prolongs the service life of the shed film; Long service life, up to 10 ~ 20 years; Low price, less than half of the steel frame; There is no need for jacking column, which not only increases the use area, but also can be plowed by machine.

The main disadvantage of this kind of greenhouse is that it requires a high degree of fixing of the scaffolding, and it is easy to break laterally if it is not fixed firmly. (5) Greenhouse with mixed arch structure. The arch frame of this greenhouse is usually dominated by steel beams, and the spacing between steel frames is 2 ~ 3 meters. Φ 6 ~ 8 mm round steel is longitudinally fixed on the steel beam, and the steel frame is in the form of suspended beam without column, and 1 ~ 2 thick bamboo poles are placed as auxiliary arches. Greenhouse with no or few columns is usually built. See figure 29.

Fig. 29 greenhouse with mixed arch structure (without hanging column)

1 .steel arch 2. Round steel 3. Bamboo pole greenhouse is an intermediate type between bamboo arch greenhouse and steel arch greenhouse, and its cultivation environment is better than the former but not as good as the latter. Because the construction cost of this greenhouse is relatively low, the ability to resist natural disasters is enhanced, and the cultivation environment is obviously improved, so it is welcomed by the majority of vegetable farmers. (6) Greenhouse with string structure This greenhouse is mainly arched with steel beams or thick bamboo poles, and the arch distance is about 3 meters. A special rust-proof steel wire or thick iron wire is pulled on the main arch frame every 20-30 cm longitudinally, and both ends of the steel wire are fixed on the ground anchor at the shed head. On the taut steel wire, a thin bamboo pole with a diameter of about 3 cm is fixed every 50 ~ 60 cm to support the greenhouse film, as shown in Figure 30.

Fig. 30 plastic shed with string structure 1. Main arch 2. Steel wire 3. According to the strength of the main arch and the span of the greenhouse, the auxiliary arch is generally built into a greenhouse without columns or with fewer columns. At present, the greenhouse with few columns is the main one.

The main advantages of plastic greenhouse with string structure are: small shade of arch frame and good illumination in the greenhouse; The shed frame is light in weight, and the number of columns in the shed is reduced, which is convenient for management; It is easy to construct, and the construction cost of shed reform is relatively low. Its main disadvantages are: the construction of greenhouse is troublesome, and the steel wire wears the greenhouse film seriously. The shed film is not tightly pulled, and the shed surface is not well drained in rainy season, which is easy to accumulate water. (7) Double-arch greenhouse The whole greenhouse has two layers of arches inside and outside, and the scaffolding is mostly steel frame structure or pipeline structure.

In low temperature period, double-arch greenhouse is usually covered with double-layer film for thermal insulation, or covered with non-woven fabric and thermal insulation quilt on the inner arch, which can increase the night temperature by 2 ~ 4℃ compared with single-layer greenhouse. In the high temperature period, the outer arch frame is covered with a sunshade net for shading and cooling, and the inner arch frame is covered with a film for rainproof, so as to carry out the cultivation of cooling and rainproof. Compared with single-arch greenhouse, double-arch greenhouse is easy to control the internal environment and has better production effect. Its main disadvantages are relatively high cost, less light transmission of double-layer film in low temperature period and insufficient light in shed.

Double-arch greenhouse is widely used in southern China, mainly to replace greenhouse for cultivation in winter or early spring. (8) Multi-span greenhouse This type of greenhouse has two or more arched or ridged roofs, as shown in Figure 3 1.

Figure 3 1 Multi-span plastic film greenhouse The main advantages of multi-span greenhouse are: the span of greenhouse is relatively large, ranging from ten meters to hundreds of meters according to the size of the plot, covering a large area and high land utilization rate; The space in the shed is relatively wide, with large heat storage capacity and good thermal insulation performance at low temperature; It is suitable for mechanization, automation and factory production management, and meets the requirements of modern agricultural development. The main disadvantages of this greenhouse are: high requirements for building materials, strict requirements for shed design and construction, and high construction cost; The roof drainage and snow removal performance is poor, and the natural ventilation and cooling effect is not good in high temperature period, which is prone to high temperature hazards.