As a common crop grown in greenhouses, the ripening process of tomatoes is affected by many factors, such as the environment and management. To harvest plump, attractively colored ripe tomatoes, you need to start from the following core links and accurately control the growth cycle:
1. Temperature control: “Accelerator” of the ripening process
Temperature is the primary factor affecting tomato ripening. The suitable temperature for tomato fruit ripening is 20-25℃, and the temperature difference between day and night needs to be maintained at 10-15℃.
Daytime management: When the temperature of the tomato greenhouse exceeds 28℃, timely ventilation or sunshade nets should be opened to prevent high temperature from causing “excessive growth” or burns of the fruit.
Nighttime insulation: In low temperature seasons (such as winter), the nighttime temperature can be maintained at 10-15℃ by heating, insulation blankets, etc., to prevent low temperature from delaying ripening. When it is below 10℃, the fruit ripening basically stops);
The effect of temperature difference: The appropriate temperature difference between day and night can promote the accumulation of sugar. For example, in an environment of 25℃ during the day and 15℃ at night, tomatoes not only mature faster, but also taste sweeter.
2. Light management: “Catalyst” for coloring and sugar accumulation
Tomatoes have a high demand for light during the ripening stage. Adequate light can promote the synthesis of anthocyanins and carotenoids in fruits and achieve uniform coloring.
Optimize light transmission: Clean the greenhouse film regularly to reduce dust and water droplets. A 20% reduction in light transmittance will extend the ripening time by 5-7 days.
Light supplement measures: In continuous rainy weather, LED light supplement (mainly red light with a wavelength of 600-700nm) can be used to supplement light for 8-10 hours a day to accelerate ripening.
Plant adjustment: Increase the light-receiving area of the fruit through pruning, branching, and leaf thinning.
3. Water and fertilizer management: “nutritional cornerstone” of ripening quality
Water control: Reduce watering from the late stage of fruit expansion to the ripening stage. Keep the soil moisture at 60%-70% . Too wet can easily lead to cracked fruit, and too dry will cause the fruit to shrivel. It is recommended to use drip irrigation to avoid flooding.
Key points for fertilization:
Fruit expansion period: topdress high-potassium compound fertilizer (N-P-K ratio 1:1:2), 10-15kg per mu, to promote fruit expansion;
Color change period: Spray 0.3% potassium dihydrogen phosphate + 0.2% glucose solution on the leaves once a week to increase sugar content and color.
Avoid excessive nitrogen fertilizer: Too much nitrogen fertilizer will cause the plant to grow too long and the fruit to mature late. So the amount of urea used needs to be controlled.
4. Ethylene regulation: “technical means” of artificial ripening
Naturally ripened tomatoes taste better, but in order to unify the time of listing, ethylene can be used to ripen them reasonably.
Plant ripening: When the fruit turns white, spray the plant with 1000-1500ppm ethephon solution, and the fruit will turn red after 7-10 days.
Post-harvest ripening: After picking the green fruit, place it in a 20-25℃ environment, soak it with ethephon (500-1000ppm) for 1 minute. And seal it for 2-3 days to ripen.
Natural ripening: If you pursue pure naturalness, you can place ripe bananas or apples next to the fruit clusters to use the natural ethylene they release to promote ripening.
5. Pest and disease control: “safety guarantee” of the ripening process
Pests and diseases can directly cause fruit rot or stop development, so it is important to prevent them:
Common diseases:
Late blight: spray with 800 times diluted metalaxyl, manganese, zinc, once a week;
Botrytis cinerea: spray with 1000 times diluted procymidone, and reduce the humidity in the greenhouse (humidity>85% is prone to disease);
Pest management:
Aphids and whiteflies: control with 1500 times diluted imidacloprid, and kill with yellow boards;
Red spiders: use 2000 times diluted avermectin, and focus on spraying the back of the leaves.
6. Harvest timing: “accurate judgment” of maturity
The maturity of tomatoes can be judged by color, hardness, and taste:
Green ripe period: the fruit is all green, hard, and suitable for long-distance transportation;
Color change period: the fruit shoulder begins to turn red, the hardness decreases, and it takes 1-2 days to mature.
Maturity period: more than 80% of the fruit turns red, the taste is best. And it is suitable for fresh harvesting.
Fully ripe period: the whole fruit is red, the texture is soft. It is suitable for processing and making sauce.
Summary: Scientific management achieves “efficient maturity.”
The maturity of greenhouse tomatoes is the result of the synergistic effect of multiple factors such as temperature, light, water, and fertilizer. By accurately controlling the environmental parameters of the plastic greenhouse, rationally using ripening technology, and doing a good job of pest and disease protection, not only can the maturity cycle be shortened (conventionally 40-50 days, 7-10 days earlier after optimization), but also the fruit quality can be improved.
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