Detailed Explanation of Key Technical Points for Tomato Cultivation in Cold Greenhouses

A cold greenhouse refers to a plastic greenhouse, which generally does not need to be covered with straw mats, has only a single layer of plastic film, and has no rear earth wall or gable walls. Tomato cultivation in cold greenhouses is relatively common. Below, the editor will explain the cultivation techniques for tomatoes in cold greenhouses.

1. Variety selection

Choose tomato varieties that are cold-tolerant, heat-tolerant, disease-resistant, high-quality, high-yielding, suitable for storage and transport, good in marketability, and adapted to market demand, such as Baoguan, Jiaguan, Jinpeng, Baili, etc.

2. Seedling raising

Soak the seeds in warm water at 55°C for 6-8 hours, remove them and wrap the seeds in a clean wet cloth, then place them at 25-30°C to promote germination. After 2-3 days, when most of the seeds have sprouted white, they can be sown.

3. Transplanting

In combination with land preparation, apply high-quality organic fertilizer per mu, and shape the land into semi-high ridges with a wide row spacing of 80 cm and a narrow row spacing of 40 cm, then cover with plastic mulch. Cover the greenhouse film 15-20 days before transplanting, fix the ground anchors well, and reinforce the greenhouse structure. Seal the ventilation openings of the cold greenhouse with 20-30 mesh nylon netting to prevent flying insects from entering. When the nighttime temperature inside the greenhouse is stably above 10°C, choose clear weather for transplanting. At this time, the seedlings are 20-25 cm tall, with a stem diameter of 0.6 cm, 7-8 leaves, already showing flower buds, dark green leaves slightly tinged with purple, well-developed roots, and no pests or diseases. Plant about 3,500 plants per mu, digging holes for transplanting at an average row spacing of 60 cm and a plant spacing of 28-30 cm, with soil covering not exceeding the cotyledons.

4. Later management

1. Fertilizer and water management

Water immediately after transplanting. To resist the cold, the water must be sufficient and thorough. After that, appropriately control watering to promote seedling hardening. When the first truss of fruit is the size of a walnut, end seedling hardening and apply nitrogen fertilizer and potassium fertilizer per mu along with watering. During the rapid expansion stage of the second and third trusses of fruit, carry out topdressing at this time. After entering the fruiting stage, spray a 0.2%-0.3% potassium dihydrogen phosphate aqueous solution on the leaves in the afternoon.

2. Temperature and humidity management

Cold greenhouses have no straw covering, so temperature control is relatively difficult, especially when cold air strikes. At this time, measures should be taken to increase the greenhouse temperature. A small arch shed can be added over the tomato seedlings inside the greenhouse, supported by small bamboo poles and covered with 1.2 m wide plastic film, opened during the day and covered at night, so that the nighttime temperature inside the small arch shed remains above 10°C.

The overall temperature management requirements are: during the seedling recovery period after transplanting, the daytime temperature should be 25-30°C and the nighttime temperature 14-16°C; in the early growth stage, 20-25°C during the day and 12-14°C at night; during the fruiting stage, 25-30°C during the day and 14-16°C at night. In the late growth stage, when the temperature is high, ventilation can be increased. When the outside nighttime temperature is stably above 12°C, the ventilation openings do not need to be closed at night, allowing ventilation day and night. In the early growth stage, the relative air humidity should be maintained at 65%-70%, and during the fruiting stage at 60%-80%.

3. Plant adjustment

Adopt single-stem pruning, promptly remove side branches, and hang vines at the appropriate time. Keep 4-6 trusses of fruit per plant and 3-4 fruits per truss, and promptly thin flowers and fruits. After flowering, use Tomatotone and 4-CPA to dip flowers to ensure fruit set, at a concentration of 20-30 mg/kg; use the higher limit at low temperatures and the lower limit at high temperatures. Add 0.1% of 50% carbendazim wettable powder to the solution to prevent gray mold.

5. Pest and disease control

Because insect-proof netting is added at the ventilation openings of cold greenhouses, tomato pests rarely occur, and generally only the whitefly needs to be controlled as a key pest. When whiteflies occur, yellow sticky boards can be hung in the greenhouse to trap and kill them. Use 30-40 yellow boards of 25 cm × 30 cm per mu, hung between rows at 0.5-0.7 m above the top of the plants for trapping and killing. Focus on controlling early blight, late blight, and leaf mold. For early blight and late blight, use 120-180 g of 45% chlorothalonil smoke agent per mu, place it in 5-6 spots, light it in the evening, close the greenhouse overnight, fumigate once every 7 days, and fumigate 3-4 times consecutively; or use 72% cymoxanil · mancozeb wettable powder diluted 800 times for spray control. For leaf mold, use 10% difenoconazole water-dispersible granules diluted 1500 times, or 47% kasugamycin · copper oxychloride wettable powder diluted 800 times for spray control. For bacterial wilt, use 72% agricultural streptomycin sulfate wettable powder diluted 4000 times for root irrigation, using 300 ml per plant, irrigating once every 10 days, and irrigating 2-3 times consecutively.

Tomato cultivation in cold greenhouses is a good planting project that can bring relatively large economic returns, but the temperature inside a cold greenhouse is difficult to control. Everyone needs to pay extra attention during the planting process.