Tomato Growing Techniques: Requirements for Soil, Light, Water, Temperature and Fertilization

Tomato is one of the most widely grown crops in China, and also a “side dish” much loved by consumers. Its planting area increases year by year, so in tomato growing techniques, what are the requirements for soil, light, water, temperature and fertilization?

1. Soil Conditions for Growing Tomatoes

Tomato is not very strict about soil; it is best to choose a deep, well-drained, fertile loam rich in organic matter. During its growth period, the tomato needs to absorb large amounts of nutrients from the soil. To produce 5000 kg of fruit, it needs to absorb 33 kg of potassium oxide, 10 kg of nitrogen and 5 kg of phosphorus from the soil. Of these elements, 73% are distributed in the fruit, and 27% exist in the stems, leaves, roots and other vegetative organs.

2. Light Conditions for Growing Tomatoes

Tomato is a short-day crop that loves light, but most varieties are not strict about daylight and do not need a specific photoperiod; as long as the temperature is suitable, it can be cultivated all year round. Generally speaking, it grows well under 16 hours of light; the light saturation point of tomato is 70,000 lux, and it can develop normally at 30,000 to 35,000 lux. At different growth stages, the tomato's light requirements are:

① Germination stage: no light is needed.

② Seedling stage: the light requirement is relatively strict; insufficient light delays flower bud differentiation, raises the position of the flowering node, reduces the number of flowers, and lowers the quality of flower buds.

③ Flowering stage: insufficient light easily causes flower and fruit drop.

④ Fruiting stage: under strong light, fruit set is greater and individual fruits are larger; under weak light, the fruit-setting rate is low, individual fruit weight decreases, and hollow fruit and rib rot fruit are more likely to appear.

3. Water Conditions for Growing Tomatoes

The aboveground stems and leaves of tomato are lush and its transpiration is relatively strong, with a transpiration coefficient of about 800, so it needs more water. However, the tomato root system is very developed and has a strong water-absorbing capacity, so its water requirement is semi-drought-tolerant in character, and a relative air humidity of 45-50% is suitable.

At different growth stages, tomato has different water requirements: during the seedling stage it grows relatively fast; to avoid excessive growth and disease occurrence, soil moisture should not be too high, and irrigation should be properly controlled; before the first truss sets fruit, too much soil moisture easily causes excessive plant growth and poor root development, leading to flower drop; after the fruit of the first truss begins to swell, the water requirement increases noticeably; during the fruit-swelling period, each tomato plant absorbs 1-2 liters of water per day; water appropriately according to soil transpiration conditions, watering little but often, and during the full-fruiting period the watering interval is 5-7 days.

4. Temperature Conditions for Growing Tomatoes

Tomato is a warm-loving vegetable. Generally speaking, it can adapt to tomato growth within a temperature range of 15-35°C. The most suitable temperature for assimilation is 20-30°C; when the air temperature reaches as high as 33°C, growth is affected; at 40°C growth stops; and at 45°C high-temperature damage occurs.

When the temperature drops below 10°C, growth is slow, and at 5°C growth stops. At minus 1-2°C, tomato will be frozen to death, but seedlings that have been hardened against cold can withstand short periods of minus 2°C. The most suitable soil temperature for tomato growth is 20-23°C; when the soil temperature drops to 6°C, the root system stops growing.

Tomato has somewhat different temperature requirements at different developmental stages:

① Seedling stage: the most suitable temperature is 20-25°C during the day and 10-15°C at night. If the temperature during the seedling stage is too high or too low, it easily causes weak seedling growth, poor flower bud differentiation and development, and reduced flower quality, and flower and fruit drop easily occur during the flowering and fruiting stage.

② Flowering stage: it is sensitive to temperature; the most suitable air temperature is 20-30°C during the day and 15-20°C at night. When the flowering stage encounters low temperatures or high temperatures above 30°C, pollen grain germination and pollen tube elongation are poor, fertilization is poor, and flower and fruit drop easily occur.

③ Fruiting stage: the suitable temperature is 24-26°C during the day and 12-17°C at night.

④ Fruit-coloring stage: the most suitable temperature is 20-25°C; above 30°C, coloring is poor.

Tomato growth and development require a certain day-night temperature difference, especially during the fruiting stage. Tomato plants carry out photosynthesis during the day to manufacture nutrients; appropriately lowering the temperature at night is conducive to the transport and accumulation of nutrients, promotes the growth of roots, stems, leaves and fruits, and thereby increases yield and quality. Therefore, in winter greenhouse tomato production, excessive nighttime heating often leads to phenomena such as excessive growth.

5. Fertilization Conditions for Growing Tomatoes

① Nitrogen fertilizer: it increases the speed of crop nutrient transport, lengthens internodes, lengthens leaf stalks and enlarges leaves. It should be used in limited amounts; when used excessively, crop internodes become longer, stems become thin, leaf stalks become extremely long, leaves become oversized and thin, and leaf color becomes light yellow; flowering is late, fruits are small, fruit swelling is slow, yield is affected, and disease resistance declines (old greenhouses must definitely use less chicken manure and compound fertilizer). Cold resistance also drops greatly.

② Superphosphate: it contains phosphorus and calcium; calcium fertilizer increases crop cell division, promotes flower and fruit swelling, makes floral organs robust, raises the pollination rate and reduces malformed fruit. When soil temperature is low, root growth is slow and it is very difficult to absorb calcium, which causes calcium deficiency, resulting in malformed fruit and rib rot fruit. As a remedy, calcium nitrate can be applied with irrigation water; when each truss of fruit grows to the size of a peanut, spraying calcium nitrate once per truss can prevent it.

③ Phosphorus fertilizer: it promotes crop root growth and determines the number of roots; when phosphorus is deficient, the number of main roots decreases, affecting nutrient transport to the crop. When plowing in the early stage, good phosphorus fertilizer must be used so the roots go deep, transport nutrients well for the crop, increase cold and drought resistance, reduce the number of waterings, and prevent severe disease caused by too much watering and high humidity.

④ Potassium fertilizer: potassium sulfate should be used when plowing; it strengthens stalks, enlarges fruits, gives the fruit good color, a glossy surface, good firmness and tolerance for transport.

⑤ Magnesium fertilizer: it increases the chlorophyll content of crops and promotes photosynthesis. When magnesium fertilizer is insufficient, irregular large yellow chlorotic patches appear on the leaves. The distribution of various trace elements is directly related to magnesium.

⑥ Zinc fertilizer: it speeds up crop nutrient transport, makes growing points grow faster, and even without yellowing or stunted heads, it also participates in photosynthesis.

⑦ Iron fertilizer: after being absorbed by crops, it inhibits bacterial growth, forms a protective film on the crop leaf surface, and improves crop disease resistance. When iron is lacking, plant leaves turn yellow and resistance declines.

⑧ Boron fertilizer: it increases crop cell division, promotes flower bud differentiation, and improves the balance between reproductive growth and vegetative growth of crops. When boron is lacking, flower buds do not form or are small.

⑨ Copper sulfate: it improves crop disease resistance and forms a waxy layer on the surface of crop leaves and stalks so that bacteria cannot invade.

Every element has an amount for use; excessive use of any element will affect the absorption of other elements.