Biological value of tomatoes and specific features of the crop cultivation in greenhouses

Biological value and nutritional significance of the tomato

The tomato is one of the key vegetable crops in the human diet, second only to cabbage in terms of consumption volume. According to medical recommendations, the annual consumption rate of tomatoes is 30 kg per person, which should account for a quarter of the total vegetable volume in the diet. The high value of the crop is due to its rich array of vitamins, carotenoids, and mineral salts. Iron occupies a special place among them, as tomatoes contain more of it than fish, milk, or chicken meat.

Tomato fruits are also a source of lycopene — a powerful antioxidant that protects the cardiovascular system. It prevents the thickening of blood vessel walls, reducing the risk of developing early stages of atherosclerosis. Furthermore, folic acid in the fruit supports hematopoiesis and normalizes cholesterol metabolism. Including tomatoes in the diet helps increase the alkaline reserve of the blood, which is especially important for people with metabolic disorders, stomach diseases, and cardiovascular conditions.

Microclimate requirements and peculiarities of plant development

The origin of the tomato from high-altitude tropics determines its requirements for growing conditions. The crop is heat-loving, but relatively cold-hardy compared to cucumber and tolerates significant daily temperature fluctuations well. For successful growing season, the tomato requires low Relative humidity air">relative humidity, moderate irrigation, and constant air circulation. Plants are able to partially absorb moisture from the air, thanks to which they suffer less than other crops from a lack of soil moisture.

• Consumption rate per person — 30 kg per year
• Root penetration depth — 1–1.5 m
• Optimal daylight hours — 12 h
• Humidity for pollen shedding — 60–65 %
• Humidity for pollen germination — 70–75 %

Temperature regime directly affects key developmental phases of the plants. The minimum threshold for seed germination is 11 °C, and the optimal range lies between 20–25 °C. To accelerate the formation of the first inflorescence, it is recommended to keep seedlings at a night temperature of 6–13 °C after the emergence of cotyledons — under such conditions, flower clusters are initiated faster than at higher temperatures. At the same time, any negative temperatures are fatal to the plants.

For effective photosynthesis, it is required to maintain the temperature within the range of 17–26 °C. This limit must be adjusted: the higher the light level and the concentration of carbon dioxide in the greenhouse, the higher the temperature should be set. The soil temperature regime is also critical for plant nutrition: the optimal values are 16–24 °C. If the soil temperature drops below 15 °C, the roots sharply reduce the absorption of phosphorus, and subsequently water.

Successful pollination of flowers directly depends on the temperature regime and air humidity in the greenhouse. The tomato is a self-pollinator, but pollen transfer is possible only under certain conditions. Pollen retains viability within strictly limited temperature frames.

Conditions for pollen germination	Permissible air temperature
Pollen germination (night)	from 15 °C
Pollen germination (day)	up to 33 °C

Exceeding the daily temperature limit makes the pollen sterile. The light regime also plays a decisive role: when light is insufficient, growth slows down, buds remain underdeveloped, and pollen loses fertility, which prevents the formation of fruit set. The optimal daylight length is 12 hours, and 24-hour lighting leads to physiological disorders in the plants.

The structure and growth habit of the bush depend on cultivar characteristics. The root system of the tomato is taproot and deeply branched; it penetrates the soil to a depth of 1–1.5 m. The stem height varies from 30 cm in dwarf cultivars to 300 cm or more in vigorous ones. Branching occurs according to the sympodial type: the growth of the shoot terminates in a cluster (a curl of 7–20 flowers), and the continuation shoot is formed from the leaf axil under the inflorescence. Lateral branches of the first order are called side shoots.

Based on the growth habit of the bush, tomatoes are divided into indeterminate, determinate, semi-determinate, and super-determinate:

• Indeterminate — characterized by unlimited growth of the main continuation shoot and strong branching. Inflorescences are initiated every 3–4 leaves, and fruiting is extended over time. This type is characteristic of mid-season and late-ripening cultivars.
• Determinate — have short internodes and weak branching. Inflorescences are formed frequently — every 1–2 leaves. The growth of the main shoot stops after the formation of 3–6 inflorescences, but it can be extended by transferring the growing point to a side shoot (side shoot). Characteristic of early-ripening and mid-season cultivars.
• Semi-determinate — occupy an intermediate position regarding the type of branching and growth.
• Super-determinate — the least vigorous and most early-ripening forms. Shoot growth stops after the formation of only 3 inflorescences, which is why they have the lowest yield.

The tomato fruit is a juicy, multi-celled berry weighing from 1 to 600 g or more. It varies greatly in shape: from the traditional round and oblate to egg-shaped, pear-shaped, pepper-shaped, banana-shaped, etc.

The flesh comes in various colors and shades: red, pink, yellow, orange, green, and brown.

Cultivation of tomatoes in greenhouses. Tomatoes are grown in winter and humid greenhouses. In winter greenhouses, tomatoes are grown in winter-spring and autumn cycles. Appropriate cultivars and hybrids have been created for each growing period.

Cultivars and hybrids. There is a wide assortment of greenhouse tomato cultivars and hybrids created by domestic and foreign breeders. The Ukrainian plant cultivar register includes more than 20 tomato cultivars and hybrids for protected soil, half of which are of Ukrainian breeding. The centers for greenhouse tomato breeding are the Ukrainian Scientific Research Institute of Vegetable and Melon Growing and its Kyiv department, as well as the State Enterprise “Scientific-Research Production Agro-Combine ‘Pushcha-Vodytsia’”. Our Ukrainian cultivars and hybrids, mainly created by Academician

V. A. Kravchenko and his school, are not inferior in terms of main indicators

Here is a brief description of the hybrids created by the team of breeders under the leadership of A. V. Kravchenko.

E, KDS-1 — early-ripening, matures in 105–107 days from emergence, fruit weight — 95–105 g, yield — 14–15 kg per 1 m². Resistant to stress and major diseases. Recommended for film and glass greenhouses.

E, KDS-5 — early-ripening, matures in 106–110 days, fruit weight — 110–115 g. Resistant to major diseases and adverse conditions, yield — 14–15 kg per 1 m². Recommended for film greenhouses.

E, Barvinok — early-ripening, matures in 103–107 days, fruit weight — 105–110 g. Distinguishable by cold tolerance and resistance to adverse conditions, diseases, and cracking. Yield — 14–15 kg per 1 m². For film greenhouses.

E, Skarb — early-ripening, matures in 103–107 days, fruit weight — 120–130 g, resistant to diseases. For film greenhouses.

E, Bohun — early-ripening, matures in 105–107 days, fruit weight — 250–300 g, denser, does not crack, resistant to diseases, very tasty. Yield — 17–19 kg per 1 m².

E, Kniazhych — medium-early, sets into beautiful, full-weighted clusters, matures in 107–112 days, fruit weight — 110–120 g, yield — 18–20 kg per 1 m², which is 1.5–2.5 kg per 1 m² higher than standard hybrids E, Krasnaia Strela, Maeva, Anabel, resistant to diseases. For film and glass greenhouses.

In recent years, V. A. Kravchenko has created a whole range of new disease-resistant indeterminate early-ripening and medium-early hybrids for hydroponic greenhouses with a yield of 28–32 kg per 1 m²: E, Elf, E, Stozhar, E, Duet, E, Dobrodii, E, Dostoinyi, E, Orbi. The highest productivity — 32–35 kg

per 1 m² — is noted in the medium-ripening indeterminate hybrid E, Plidnyi. V. A. Kravchenko’s hybrids exceed the existing standards E, Maeva and Podmoskovnyi by 2–5 kg per 1 m².

Practically all of the listed hybrids are also recommended for film greenhouses. Along with this, determinate early-ripening hybrids have been created specifically for film greenhouses: E, Shafer, E, Evo with a yield of 16–22 kg per 1 m².

A number of E tomato hybrids were created under the leadership of breeder M. D. Drokin. Indeterminate early-ripening for film greenhouses — Antoshka, Charivnyi; indeterminate late-ripening for glass greenhouses — Nezalezhnyi, Suziria, Alla E, Alla E (Raisa type). The last four mentioned hybrids were created with the active participation of the talented breeder H. I. Hnatiuk.

Tomato cultivars of Ukrainian breeding: Kashtan, Mriia, Ukrainets — deserve attention for their large fruits, high yield, early ripening, and flavor qualities.

Among the assortment of E hybrids of Russian breeding, one should note the hybrids of the E selection firm "Ilyinichna": Krasnaia Strela (the most popular), super-determinate — Olya, Bumerang, Prekrasnaia Ledi; semi-determinate — Podmoskovnyi, Arlekin; determinate — Natus, Markiza, Severnyi Ekspress; indeterminate — Vasilievna, Divo, Vlad, Baiaderka, Titanik; large-fruited — Favorit, Kentavr; cherry-type — Brusnika, Popugaiychik. E tomato hybrids for protected soil from the Russian firm "Gavrish" enjoy well-deserved popularity. Indeterminate — Figaro, Maidan, Atos, Aramis, Portos, Miledi, Funtik, Svetofor. Especially attractive are decorative cluster tomatoes (harvested in whole clusters) — Samara, Intuitsiia, Refleks. Semi-determinate — Margarita, determinate — Verlioka, Blagovest and more advanced ones created on their basis, Master, Kartu, etc.; super-determinate — Druzhok, Leopold, Betta and Gavrish, which do not require pruning.

The "Mapul" firm has created a number of interesting cold-resistant tomato hybrids mainly for film greenhouses and covers. Many of them are also adapted for cultivation in open soil. E determinate hybrids Shustrik, Bolshoi Brat, Bolshevik, Piatachok of early maturity (105–110 days from emergence) are famous for their high commercial qualities. Arbat and Rover are more fast-ripening (100–105 days), with a smaller fruit weight — 80–100 g. Shustrik is distinguished by its remontancy, rare for a determinate tomato, i.e., the ability for prolonged flowering and fruiting. Highly decorative super-fast-ripening E hybrids, Arctica (fruit weight 10–15 g) and Gorozhanin (fruit weight 35–50 g), have been bred for balcony cultivation.

In greenhouses, tomatoes are grown in winter-spring and autumn crops.

Seedling production and temperature regime

To obtain healthy tomato seedlings for the winter-spring season, it is necessary to strictly control temperature and light levels. Any deviations from the technology in the early stages lead to seedling etiolation and a delay in the formation of the first inflorescence. High-quality transplants should be stocky, with a developed root system and formed buds.

1. Soaking calibrated and treated seeds in a solution of macro- and micronutrient fertilizers, followed by germination at a temperature of 23–25 °С.
2. Sowing prepared seeds into seed trays or the soil of propagation greenhouses while maintaining the soil temperature at 23–25 °С until seedling emergence.
3. Pricking out seedlings into individual 10×10 or 12×12 cm nutrient pots immediately after the formation of the first true leaf.
4. Spacing out the grown plants two weeks before transplanting to their permanent location to prevent stem elongation and mutual shading.

The timing of seed sowing and the transplanting of ready-to-plant seedlings are tied to the climatic growing zones. Adhering to these dates allows plants to develop under optimal natural light conditions:

Growing zone	Seed sowing dates	Transplanting dates to greenhouse
Polesie	Third ten days of November — beginning of December	Second ten days of January
Forest-steppe zone	Second ten days of November	First ten days of January
Steppe zone	End of October — beginning of November	Third ten days of December

During the growing process, seedlings must be supplemented with artificial lighting to compensate for the lack of winter sun. When evaluating seedling readiness before transplanting to their permanent location, use the following technical indicators:

• Seedling age — 50–60 days
• Plant height — 25–30 cm
• Number of leaves — 7–9 pcs.
• Lighting power — 160–200 W/m²
• Duration of artificial lighting — 12–16 hours per day
• Spacing density — 24–28 plants/m²

For healthy seedling development, maintain an air temperature of 19–20 °С during the day and 15–16 °С at night. The soil temperature should remain between 18–20 °С at an air humidity of 60–65 %. Before starting the transplanting process, carry out a thorough culling and remove all diseased or underdeveloped plants.

Transplanting, canopy shaping and harvesting

Seedlings are planted in double-row bands with a spacing of (90–100 + 50–60) × 40–45 cm, which corresponds to a density of 2.5–3.3 plants per 1 m². Vigorous hybrids are spaced further apart, while medium-growing ones are placed more densely. 3–5 days after establishment, plants are tied to a vertical trellis at a height of 2 m and, as the stem grows, it is regularly twined around the twine.

Shaping the canopy depends on the growth type of the specific hybrid or cultivar. To obtain maximum yield per square meter, the following schemes are used:

• Indeterminate hybrids. Plants are maintained strictly in a single stem. Side shoots (suckers) are removed in the morning when they reach a length of 3–5 cm. Up to the trellis height, 9–12 inflorescences are formed, after which the stem is passed over the trellis wire. After allowing 4–5 more inflorescences to form, the top is gradually lowered at an angle of 40–50°, tied to adjacent stems, and pinched at a height of 50 cm from the ground. Plastic S-shaped hooks are convenient for this operation.
• Determinate cultivars and hybrids. One of three approaches is applied: growing in a single stem until natural growth limitation; growing in a single stem while retaining 2–3 side shoots with one inflorescence on each (under the inflorescences); or shifting growth to a side shoot from the axil of the 2nd or 3rd leaf, while pinching the main stem above the 4th–5th inflorescence.

To create an optimal microclimate in the greenhouse, temperature and humidity parameters are adjusted depending on the light intensity and the growing season of the plants. This helps to avoid plant stress and prevent the development of diseases:

• Air temperature. In clear weather with light levels up to 20 klx, the air is heated to 19–23 °С during the day. On cloudy days (with light levels less than 5000 lx) and at night, the temperature is reduced to 16–18 °С. As light intensity increases to 40–50 thousand lx, the temperature is raised by 2 °С for every additional 10 klx.
• Soil moisture. During the period of vegetative mass growth, soil moisture is maintained at 65–70% of field capacity, and with the onset of fruiting, it is increased to 75–80% of field capacity. Mulching with chopped straw helps retain soil moisture and reduces air humidity.
• Soil temperature and soil management. The soil temperature is consistently maintained at 18–20 °С. If the soil has good physical properties, loosening is not necessary. Loosening and digging are resorted to only in cases of severe substrate compaction.

Harvesting begins 2–2.5 months after planting transplants. Tomatoes are harvested every 2–3 days at the blanch stage — this accelerates the ripening of the remaining fruit set on the plants. The final yield depends on the duration of the growing season:

Crop type	Growing season	Average yield, kg/m²	Maximum yield, kg/m²
Short-term crop	Until the end of June	11–12	15
Extended crop	Until the end of October	16–18	25–40

Autumn tomato rotation: timing, maintenance, and microclimate

The autumn tomato crop allows for extending the harvesting of fresh fruits until the beginning of winter. During this period, it is important to strictly adhere to the dates for sowing seed and planting transplants, adapted to the specific natural and climatic zone.

Growing zone	Sowing seed	Planting transplants in a greenhouse
Polissia	June 10–15	July 20–25
Forest-steppe zone	June 20–25	August 1–5
Steppe zone	July 5–10	August 10–15

Favorable natural lighting conditions in summer make it possible to shorten the transplant growing period to 30–35 days. Plants are set according to a (100 + 60) × 40–45 cm pattern and are pruned strictly to a single stem. The apex is pinched before a sharp deterioration in lighting, leaving 1 to 3 leaves above the top (6th–7th) cluster. When clearing the crop in early November, one leaf is left, and in late November or early December — 2–3 leaves. This agricultural technique increases the yield of the upper clusters by 0.6–0.8 kg per 1 m². As in the winter rotation, the lower leaves are removed, and the flowering clusters are vibrated to improve pollination.

The autumn tomato crop is usually grown after cucumber. The soil remains rich in nutrients after it, so there is no need for additional fertilizer application.

• Relative humidity — 60–65 %
• Air temperature during the day (November–December) — 18–20 °С
• Soil temperature (November–December) — 17–18 °С
• Irrigation rate in August — 12–15 l/m²
• Average yield — 7–8 kg/m²

It is necessary to regulate relative humidity within the range of 60–65% by running heating and ventilation units and subsoil heating with simultaneous opening of the transoms. As the day length decreases, the temperature is lowered: in November–December, it should be 4–6 °С lower than in August. In August, tomatoes are irrigated at least twice a week, in October — once a week at a reduced rate, and towards the end of the growing season — even less frequently. The autumn rotation concludes in late November or early December. With good maintenance, the yield reaches 10 kg of fruit per 1 m².

Growing in plastic greenhouses: soil preparation and transplants

Growing tomatoes in protected soil is a reliable way to protect plants from late blight, which they universally contract in open soil due to unfavorable weather. For plastic greenhouses, indeterminate and determinate cultivars with medium and high stems are best suited. However, before starting, one should evaluate the economics: the tomato begins fruiting 40–60 days later than the cucumber under the same conditions, and the yield is 2–3 times lower.

The tomato reacts negatively to an excess of fresh manure: excessive nitrogen nutrition stimulates the growth of green mass to the detriment of fruit set. If the previous crop was cucumber, for which manure was already applied, the soil is not additionally fertilized. In other cases, to obtain a high yield, the land is prepared in advance.

1. Autumn preparation. 40–50 kg of humus or peat, 80–100 g of superphosphate, and 40–50 g of potassium sulfate are applied per 1 m² before ploughing.
2. Spring fertilizer. Ammonium nitrate is additionally applied at a rate of 30–60 g per 1 m².
3. Improvement of physical properties. Loosening agents are added to the arable layer — straw chaff (2–3 cm long) or sawdust in a volume of 30% of the total soil mass.

To prevent viral diseases, seeds are treated before sowing in a 20% solution of hydrochloric acid, after which they are thoroughly rinsed in running water. The planting dates for transplants depend on the type of greenhouse: in permanent glass winter greenhouses, they are planted in January (first harvest in April); in spring heated plastic greenhouses — in March (harvest in early May); and in unheated ones — in April (harvest in early June).

The age of transplants directly determines the timing and volume of the early harvest. For 55-day-old transplants (when sown in the forest-steppe zone and Polissya between February 10–20, and in the steppe zone between February 1–10), fruiting begins 55–60 days after planting. In the forest-steppe, the first fruits are harvested on June 15–20. Plants from 50-day-old transplants manage to produce up to 3.5–4.1 kg of fruit per 1 m² in greenhouses by the time tomatoes in the open field begin to ripen, which accounts for almost half of the total harvest.

The start of tomato fruiting in unheated spring greenhouses can be adjusted by the age of the transplants. Using older plants with already formed generative organs significantly accelerates the production of the first yield. For instance, in experiments, ripe fruits in unheated plastic greenhouses are obtained as early as the third ten-day period of May when planting 80-day-old transplants with fruit set.

Transplant type	Start of fruiting period
50-day-old	Base period
65-day-old (with flowering cluster)	8—12 days earlier
80-day-old (with fruit set)	20—25 days earlier

Pricking out seedlings and substrate preparation

To fill the planting containers, a nutrient soil mixture with a high organic matter content is used. The substrate is prepared in advance by thoroughly mixing the components to obtain a homogeneous structure.

• Sod soil — 1 part
• Humus — 8 parts
• Sand — 5 %