(a) greenhouse construction:
Choose a place close to the town, with convenient transportation, moderate location, flat terrain, sunny lee and irrigation conditions to build a greenhouse. Greenhouse specifications: generally 30 ~ 80m long and 10 ~ 16m wide. Arch can be used, and the frame can be made of bamboo, wood or light angle steel (or aluminum alloy pipe). Covered with aging-resistant agricultural PVC film.
Construction method: first level the nursery in autumn, and then set up the shed in February-March of the following spring. The shed height is 2 ~ 2.5m, and the pile height on both sides is1~1.2m.. Open the doors and windows at both ends. Open a row of skylights with a diameter of 60-80 cm on the roof every 6-8 meters. There are side windows on both sides. Skylights and side windows can be opened and closed freely to adjust the temperature in the shed. Scaffolding stakes (or angle steel) should be buried deeply, fastened, fastened (or welded firmly). The aluminum wire that compacts the plastic film should be firmly tied, and the part of the film that contacts the ground should be compacted with soil to prevent wind damage. Build seedbeds, roads, channels or sprinkler irrigation facilities on the ground in the shed.
(2) Management of greenhouse:
1. Ventilation management:
It is the key to the success or failure of greenhouse seedling raising. The temperature in the greenhouse changes with the rise and fall of the outside temperature, so the ventilation in the greenhouse must be adjusted in time with the constant change of the outside temperature and the needs of seedling growth and development. Take Pinus tabulaeformis seedlings as an example: when the temperature is about 65438 02℃, the seeds begin to germinate, when the temperature is about 20℃, the germination is the fastest, and the pine seedlings grow most vigorously between 20℃ and 25℃. Therefore, when the outdoor temperature is low in April, only the doors and windows at both ends can be opened for ventilation during the day. From the beginning of May to the end of July, the outside temperature is high and the pine seedlings grow vigorously. When the temperature in the shed rises to 30℃, first open the doors and windows at both ends for ventilation; At noon, the temperature continues to rise, and then open the skylight and side window for ventilation; When the temperature rises to 38℃, in addition to opening the skylight and the side window, it is necessary to uncover the films on both sides to release the bottom air. After 5 pm, when the temperature in the shed drops to 25℃, the window should be closed in time to raise the temperature appropriately to maintain the normal temperature at night. In hot season, when the daily minimum temperature is above 10℃, it is not necessary to open the window at night. Generally, it does not exceed 30℃ in the shed during the day, and it is about 15℃ at night. In August, the outside temperature dropped, and 10 entered a low temperature period at the end of the year. If it is not planted in the same year, the plastic film can be removed in early September to exercise the seedlings and enhance the wintering ability. Cover with plastic film before the cold comes.
2. Lighting management:
The light source in the greenhouse mainly uses solar radiation. The light transmittance of plastic film can reach 75% ~ 80% of daily radiation, but it will gradually drop to about 50% after a period of use. If the plastic film is seriously polluted, there is a lot of dust attached, or water droplets are attached, the transmitted light is even less. Especially in winter, with the weakening of natural light, the sunshine time is shortened and the light is insufficient, so auxiliary lighting is needed. Otherwise, even if the temperature rises and the light is insufficient, it will not produce good results. Auxiliary lighting can use sodium lamp, white fluorescent lamp, etc.
3. Seedling management:
Sowing in greenhouse can be done in containers or low beds. Always keep moist after sowing. After the seedlings come out, they must be irrigated in time because of the high temperature, large transpiration, fast growth and large water demand in the shed. Generally, in the fast-growing period of seedlings, irrigation should be carried out 3 ~ 4 times a day. Fertilization and irrigation should be coordinated, and the ratio of fertilizer to water is about 1: 200. In a closed greenhouse, with the increase of photosynthesis of seedlings, the amount of carbon dioxide gradually decreases, so propane gas can be burned in the greenhouse to increase carbon dioxide and strengthen the assimilation of seedlings. In addition, due to the high temperature, high humidity and rapid bacterial reproduction in the greenhouse, lodging disease is very easy to cause, especially when cultivating pine seedlings, it is necessary to prevent it in time.