The external environmental temperature changes from low to high during this crop cultivation period. The seedling stage and vegetative growth stage occur during the cold and low-light winter season. Therefore, maximizing the utilization of sunlight and energy-saving solar greenhouses to maintain suitable temperatures and light intensity for tomato growth and development is crucial for achieving high-quality and high-yield winter and spring tomato crops.
Tomato Variety Selection
Select high-yielding varieties that are tolerant to low temperatures, low light, disease-resistant, and suitable for local cultivation. Mainly cultivated varieties in northern regions include Zhongyan 998, Prosperity 872, Cherry (74-587), European Crown, Difni, Caruso, Splendor, Paulita, Delio, and Qidalie.
Tomato Seedling Cultivation
Seedlings are generally cultivated in plastic greenhouses or nurseries using seedbeds, nutrient blocks, or seedling trays. The sowing period is determined by seedling age, planting period, market time, and cultivation area. In North China, seedlings are cultivated in early December, while in Northeast China, they are cultivated in January. Seedling age is typically 35 to 45 days.
Preparation Before Tomato Planting
- Bed Preparation: Approximately 15 days before planting, cover the greenhouse with plastic film to increase indoor temperature. About a week before planting, apply base fertilizer with organic fertilizer at 4000-5000 kg/acre, ammonium dihydrogen phosphate at 25-30 kg/acre, and potassium sulfate at 10-15 kg/acre. Prepare ridges with a width of 80-90 cm, a height of 15-20 cm, ridge spacing of 50-60 cm, or narrow rows with row spacing of 60-80 cm and plant spacing of 40-60 cm. Create small grooves in the middle of the ridge to facilitate subterranean irrigation, ensuring consistent groove width and depth. Two to three days before planting, fumigate the greenhouse space with 4 grams of sulfur and 8 grams of sawdust per cubic meter by igniting them for a day, followed by ventilation before planting. Additionally, apply 50% carbendazim wettable powder at 1.5-2.0 kg/acre to the ridge surface for soil disinfection.
- Integrated Straw Reactor: Constructed ten days before tomato planting, the straw reactor comprises 4000-5000 kg of straw, 120-200 kg of bran, 100-150 kg of cake fertilizer, and 8-10 kg of fungus per acre. The fungus is activated by thoroughly mixing it with bran and adding approximately 200 kg of water per kg of bran.
Fruit Crop Management in Solar Greenhouses
- Temperature and Humidity Control: During the initial 5-7 days after planting, maintain a closed greenhouse to promote seedling growth. Keep the daytime temperature between 25-30°C and nighttime temperature between 15-20°C, with relative humidity at 80%-90%. Use internal straw reactors to eliminate the need for inter-row cultivation. Cultivate the soil every 2-4 days to improve soil temperature, enhance aeration, and promote root growth and early seedling growth. From the end of the seedling stage to the fruiting stage, maintain daytime temperatures at 25-28°C and nighttime temperatures at 13-15°C, with relative humidity between 60%-70%. Increase ventilation during the fruiting stage, with daytime temperatures of 20-25°C and nighttime temperatures of 13-15°C, and relative humidity between 50%-60%. When the lowest nighttime temperature does not fall below 15°C, conduct day-night ventilation. Implement a “four-stage temperature treatment” for improved growth and yield.
- Light Management: Given the short daylight hours and weak sunlight during the winter and spring tomato growing period, it is essential to ensure that the greenhouse receives adequate light intensity (3,000-35,000 lux) for normal growth. Measures such as using light-transmitting and insulating non-drip films, covering and uncovering straw mats or insulation blankets appropriately, regularly cleaning greenhouse films, hanging reflective curtains on the back wall of the greenhouse, pruning, removing diseased, old, and yellowing lower leaves, and supplemental lighting can increase light intensity.
- Fertilization and Irrigation Management: Implement alternating light and dark trench watering or drip irrigation methods, along with alternating organic and inorganic fertilization. Apply 10 kg of urea, 15 kg of ammonium dihydrogen phosphate, and 10 kg of potassium sulfate per acre during post-planting fertilization, followed by periodic irrigation and fertilization during fruiting.
- Carbon Dioxide Fertilization Technology: During the autumn and winter seasons, when greenhouse ventilation is reduced, prolonged ventilation and the use of carbon dioxide fertilization technology are necessary to prevent carbon dioxide deficiency, which can affect photosynthesis and crop growth. Implement carbon dioxide fertilization 30 minutes after uncovering straw mats on sunny days to increase indoor carbon dioxide concentration to 900-1500 mg/kg and ventilate after 2 hours. Studies have shown that using carbon dioxide can increase fruit set by 15%-20% and yield by 20%-30%, with improved sugar content and organic acid content.
- Pruning and Fruit Dropping: Prune and drop fruit in a timely manner to ensure proper growth and fruit development. Various pruning methods, such as single stem pruning, multiple fruit single stem pruning, and continuous topping, are commonly employed to regulate plant growth, improve fruit quality, and increase yields. Prune to leave 3-4 fruits per cluster for large-fruited varieties and 4-5 fruits per cluster for medium-fruited varieties. Remove excess branches and leaves when they reach 2-3 cm in length.
- Flower and Fruit Preservation: As the winter and spring tomato flowering period often coincides with prolonged cloudy and rainy days, resulting in poor pollination and fruit set, it is essential to implement flower and fruit preservation measures. Use 30-50 mg/kg of PCPA for flowering during the flowering period. If conditions allow, use bumblebees for pollination to improve fruit set. Bumblebee-pollinated tomatoes have more seeds and produce plant hormones that promote fruit growth, resulting in larger fruit size and increased yields.
- Improving Tomato Quality: Implement bagging with polyethylene plastic film or paper bags to promote fruit ripening and improve tomato quality and economic benefits. Additionally, spraying a 1.5% glucose solution can enhance the taste and appearance of tomatoes.
Tomato Harvest
Determine the appropriate harvest time based on specific requirements. For long-distance transportation lasting 1-2 days, harvest during the color-changing stage, when most fruits are dry, pale green, with a red top, firm texture, and good storage and transportation characteristics. For local sales, harvest during the ripe stage, when approximately one-third of the fruit turns red, and the fruits soften, offering high nutritional value and optimal taste. In recent years, the cultivation area of hard fruit tomatoes has gradually expanded due to their longer storage period. The harvest period for ripe tomatoes can last for 10-20 days, resulting in significantly improved tomato quality.
Post time: Mar-11-2024