Principles for the Production of Tomatoes in the Greenhouse

Abstract

Greenhouse technology is the technique of regulating the environmental factors for the benefit of the plant (tomato) under protective cultivation. Production of tomatoes in the greenhouse involves two stages: nursery and greenhouse. In the nursery, the plants are seeded in small cavities of the nursery tray and arranged in the nursery chamber or a small-sized tunnel where they are given maximum care. At 3–4 weeks after seeding, when they must have developed four true leaves and a well-developed root system, the seedlings are transplanted into the bigger tunnel. The transplants are given water through drip irrigation. The nutrients are supplied through fertigation in the required quantity and concentration. Pest control is done by integrated pest management system (a combination of physical, biological, and sometimes chemical control).

1. Introduction

Tomato is widely cultivated for its fleshy fruits that have special nutritive value. It is the world’s second-largest vegetable crop following potato, and it is the most canned vegetable. Tomato is one of the most important vegetable crops produced by farmers in Nigeria with a demand gap of 2.3 million tons [1, 2]. Tomatoes can be eaten raw or processed. It could be processed into paste, tomato ketchup, soup, juice, diced, sauce, puree, etc. It is rich in nutrients, dietary fiber, and antioxidants such as lycopene and beta-carotene that prevent cells from cancer. It has high levels of vitamin A and C and some minerals such as iron and phosphorus [3].

Tomato production in Nigeria requires serious attention as the demand for domestic and industrial use has brought about peak rates in recent times. Tomato being one of the essential staple foods rich in minerals, carbohydrates, and vitamins is an important vegetable with premium and high processing values as well as a venture with production capacity to generate employment. In an attempt to achieve food-secured status as a nation, it is therefore pertinent to improve the production of tomatoes in Nigeria. However, generally, agriculture in Sub-Saharan Africa is rainfall-dependent, which is one of the factors debilitating the production output of agricultural produce. This dependence on climate/natural environment predisposes the crop plants to lots of dangers, such as pest and disease infestation and environmental stress due to various weather extremes, resulting in poor-quality fruits and ultimately low yield. Kaduna and Kano states, which produce 43% of national production, have a yield of 7–10 tons and sometimes 15 tons per ha [2]. So now it is imperative to emphasize the adoption and use of a protected farming system, such as screen houses and greenhouses for the production of especially high-valued or premium vegetables or crops like tomatoes. This chapter, therefore, elucidates on basic principles of greenhouse tomato production.

Greenhouse production is more expensive than producing the same crop in the open field [4]. The most important factors determining costs are depreciation of the structure and equipment, labor, energy, and variable costs such as planting material, substrate, and fertilizer.

As the term implies, principle refers to a basic idea or rule that explains or controls how something happens or works.

1.1 Advantages of greenhouse tomato production

1. The controlled environment allows for growing exotic fruits such as beefsteak for export.

2. It offers all-year-round production and quality produce.

3. Production in the greenhouse is more efficient than in the open field, which results in higher yield.

4. It is an intensive system that maximizes limited space and water.

5. Efficient utilization of agrochemicals to control pests and diseases.

1.2 Disadvantages of greenhouse tomato production

1. It is capital intensive

2. The energy requirement is high

3. Requires technical skills

2. Greenhouse structures

Tomatoes can be grown in every type of greenhouse, provided it is sufficiently high to manage and train the plants vertically. Generally, greenhouses can be classified into three based on structure: wooden (which could also be bamboo) framed, pipe framed, and truss framed. The cover could be glass, plastic film, or rigid panel. The cover must have high light transmission, and importantly photosynthetically active radiation (PAR) that falls within the range of 400–700 nanometers. In the central- and north-European countries, the Venlo-type glasshouses are mostly used. They typically have 3.2, 4, 6.4, 8, 9.6, 12, 12.8, and 16 m standard spans and 5–7 m gutter height to allow high wire planting systems [5, 6, 7]. There are variations in the dimensions, structures, and coverings used in the construction of greenhouses from one country to the other. For instance, most of the greenhouse facilities used in China are unheated [8].

3. Substrates and substrate systems

There is relatively little commercial tomato production done directly in the soil, except for organic growers. In large greenhouse complexes in developed countries, 95% of greenhouse tomatoes are grown on inert artificial substrates, a system usually referred to as soilless culture. The term “hydroponic” can refer to soilless culture or to systems such as the nutrient film technique (NFT), in which no solid substrate is used and water flows almost constantly down troughs holding plant roots [9, 10, 11].

There are many types of growing systems for greenhouse tomatoes, which include NFT (nutrient film technique), PVC pipes, sand, ground culture (in the soil), troughs, rock wool slabs, and various types of aggregate media. The various aggregate media include peat moss and peat–lite mixes, perlite, rock wool aggregate, glass wool, pine bark, and so on. In a trial of growing media at the University of Arizona [8], there were no significant differences in the yield of greenhouse tomatoes between five different media (coconut coir, perlite, peat–vermiculite mixes, coir/perlite, and rock wool).

4. Selection of variety

The first step in carrying out a successful crop production is the choice of good variety. Growing a variety that is not the best choice, or using seeds that are not of the best quality, reduces your potential for success at the outset. It is smart to start with the greatest potential rather than limiting yourself by using inferior seeds, even if it saves some money. Numerous tomato varieties are being pushed into the market, but only a few are suitable for greenhouse production. For greenhouse tomato growers, indeterminate tomato varieties are recommended. In indeterminate tomatoes, the growth of the stem is continuous and this allows for continual fruit production.

The selection of the best indeterminate seed to buy should be based on the following criteria:

1. size of fruit desired.

2. disease resistance.

3. Lack of physiological problems, that is, cracking, cat-facing, blossom-end rot.

4. uniformity of fruit size.

5. market demand.

5. Nursery

The success of a production cycle starts with acquiring healthy seedlings. Good healthy seedlings can be purchased from a commercial nursery. Also, the farmer can grow his seedling. Most greenhouse operators grow their seedlings. This is very desirable because it reduces the possibility of importing new diseases and insects [12]. Notwithstanding, in many other countries, seedlings are being raised successfully by special nursery farms that sell economical and high-quality seedlings to local growers with the aid of modern technology. Transplant raising is a crucial stage in greenhouse vegetable production. The performance of a crop depends largely on the attention paid to the care given to it when it was in the nursery.

Quality seedlings are plants free from pests and diseases, quickly grown with no suppression of yield due to poor quality roots. Transplant production takes about 3 weeks, depending on temperature and light conditions. Tomato seed germinates best at 25°C, while seedling growth is optimal at 18°C night-time minimum and 27°C daily maximum. Germination rates are at least 95% and so only one seed needs to be planted per cavity. The ideal transplant size is when the seedling has four true leaves (Figure 1). A good seedling is as wide as it is tall and has not started flowering.

Figure 1.

A typical tomato seedling ready for transplanting.

5.1 Step-wise procedure for raising a nursery

The following are the tools and materials needed for a successful nursery production: nursery tables, nursing trays, knapsack sprayer, substrate (peat moss, cocopeat, sawdust, or sterilized soil), indeterminate tomato seeds, and clean water.

5.1.1 Procedure

1. The clean trays are arranged on the nursery table.

2. The substrate is collected in a clean bowl. Moisten the substrate by spraying with water while turning.

3. The growing cavities of the trays are filled with substrates.

4. Make a depression in the cavities which are already filled with substrates.

5. Place the seeds in the depression made at one per cavity.

6. Spray with water.

7. Cover the seeds with the substrate.

8. Spray with water again and place in a dark room.

9. At the sight of the emergence of the first plumule, remove all the trays from the dark room and place them in the nursery.

10. Spray with water two or three times daily depending on the weather. Just ensure it does not go dry.

11. At about 1 week after germination, you may supplement with fertigation depending on the type of substrate used.

12. A typical fertigation program for the nursery involves dissolving 10 g water-soluble poly feed fertilizer with micronutrients in 15 l water. The fertigation water is alternated with clean water every 2 days.

13. The seedlings are ready for transplanting when they have four true leaves and a well-developed root system. Typically, this is at 2–3 weeks for tomatoes and 3–5 weeks for peppers after seeding.

6. Transplanting

Transplanting of tomato seedlings into the greenhouse is often carried out when they have reached the height of 7.5 cm to 10 cm [13]. The media or substrate of any type chosen requires to be thoroughly wet with water or diluted nutrient solution several hours prior to planting. The plants should be checked for any individual that fails to establish after planting. They will have to be changed. To keep the substrate moist, plants will require irrigation with diluted fertilizer solution as often as necessary. A good general rule of thumb is to maintain moisture at a level where only a few drops of water are needed to compact the soil into a clump [14].

6.1 Plant population

It is important to use the proper planting density when growing greenhouse tomatoes. Using a higher planting density will cause the yield per plant to decrease. This is basically due to plants shading each other. The costs and the amount of labor required also increase with more plants. Likewise, crowding plants tends to encourage disease proliferation because sprays cannot easily penetrate the thick foliage and foliage does not dry as readily. Plants should be arranged in double rows, about 4 feet apart in the center. Within a row, plants will average 14–16 inches between stems [15].

6.2 Step-wise procedure for establishing plants in the greenhouse

Tools and materials needed are grow bags, plastic mulch, twine, soil, sterilizing pan, cooling pan, binding wire, spade, manure, wheelbarrow, firewood, lighter, NPK 15:15:15 fertilizer, iron rod, tape rule, hammer, and drip irrigation kit.

6.2.1 Procedure

1. Layout: four iron rods are used to mark a rectangle inside the tunnel. The beginning is marked at 1 m away from the front and back nets each and 0.5 m away from the right and left nets each. Along the width of the rectangle, the iron rod is used to mark the beds (0.75 m) and the furrows (0.5 m). This is done at the front and back of the tunnel. A twine is tied to the rod at the front and back, respectively, to make a straight line.

2. The beds are made along the line of the twine. As such an 8 × 24 m tunnel will contain six beds and each bed will contain two rows of tomatoes.

3. The iron rods are removed and drilled closer to each other to divide the width of the bed into three. This is done for each of the beds.

4. The plastic mulch is laid on the bed. The edges of the mulch are buried with soil.

5. Sterilization: soil sterilization is essential due to the prevalence of bacteria wilt and nematodes in the soil. The manure is first turned into the frying pan and continuously stirred. It is allowed to fry but not burnt after which the soil is turned in. The soil is mixed with the manure 2:1 ratio. The mix is continually turned now and then for about 30–60 mins depending on the intensity of the fire, and the soil will be taken out when 100°C is attained with the aid of a thermometer.

6. Thereafter, the soil is transferred into the cooling pan where it is allowed to cool before sharing into the grow bags at 20 kg each. The bagged soils are arranged on the beds in the tunnel at 80 bags per bed.

7. Base application of NPK 15:15:15 is applied and mixed thoroughly with the soil.

8. The drip lines are installed, and the soil is continually watered for about 2 weeks to mineralize the fertilizer before transplanting.

9. Transplanting should be done in the evening when the weather is cool.

10. The soil is watered and holes are drilled at the spot where the water drips.

11. The nursery is watered before transplanting to ease removal from the cavities.

12. At transplanting, the plantlets are carefully placed in the drilled holes and covered with the soil to the plant collar. The soil is pressed lightly to hold the plant root in place.

13. Water is supplied for about 5 mins. Care should be taken to ensure all the emitters are dripping and the plantlets are all receiving water.

14. At 2–3 weeks after transplanting, the binding wire is tied to the rod at the front and the corresponding one at the back along with the beg.

7. Growth and development

Growth and development continue in the greenhouse after transplanting (Figure 2). The management techniques include: Irrigation, fertigation, desuckering, staking and trellising, application of fruit-setting solution, defoliation, cleaning of filters, and flushing of driplines.

Figure 2.

Tomato plants grown directly on the soil at 2 weeks after transplanting.

7.1 Irrigation

Large amounts of high-quality water are needed for plant transpiration, which serves both to cool the leaves and to trigger the transport of nutrients from roots to leaves and fruits. For instance, the amount of water needed by the greenhouse in the Netherlands is about 0.9 m³/m²/year [16]. Therefore, before building a greenhouse, it is essential to ascertain that there is adequate, quality water available all year round. EC should be <0.5 dS/m, pH from 5.4 to 6.3 and alkalinity <2 meq/l [9].

In the greenhouse, water supply is by drip irrigation (surface or sub-surface). This allows for efficient uptake of water and nutrients when mixed with fertilizer [17]. The water and nutrients are delivered to the active root zone thereby reducing nutrient loss by leaching or soil fixation. Also, the vegetative part of the plant does not come in contact with water, which reduces the growth of infection.

The frequency of irrigation varies with substrate rooting volume and its water-holding capacity. The water requirements of plants also depend on the growth stage of the plant and the season. The quantity of water required could vary from 1 to 14 l/m²/day (0.4–5.6 l/plant/day) [4, 18, 19]. Generally, water consumption increases with the growth of the plant. The water is either gravity-fed or pumped with a mini pumping machine.

7.2 Fertilizer application

Nutrient supply to the greenhouse plants is done by nutrigation or fertigation. Nutrigation is an acronym for the two words “nutrient” and “irrigation” just as fertigation is a blend of “fertilizer” and “irrigation,” hence the application of water-soluble fertilizer with the irrigation water. This allows for precision and frequency in nutrient supply, especially when the water is delivered with drip lines. Also, the nutrient is delivered to the plant even when the plant is inaccessible. The fertilizer to be applied at a particular time depends on the developmental stage of the plant and the soil test result [20], which consequently inform the design of the fertigation program. For instance, more nitrogen is supplied at the vegetative stage of the plant, while potassium is supplied during flowering and fruiting. A typical fertigation program supplies 500 g polyfeed with micronutrients (e.g., Haifa Bonus) per 1000 L water for the first 2–3 weeks after transplanting. Potassium-nitrate (e.g., Maxi K) is supplied at 2 kg/1000 L water at pH 5.6–6.5 and E.C 1.2–1.6 from week 4 after transplanting onwards, and 2 kg calcium-nitrate (e.g., Haifa CalNit) at about 4 weeks after transplanting onwards. Pavani et al. [21] recommend supplying WSF 19% each of NPK at 3.75 G/M two times in a week from 21 days after transplanting, 3 g/l micro nutrient 2–3 times from 60 days after transplanting once in 30 days, and calcium nitrate 2–3 times once in 15 days.

The fertilizer is dissolved in a bucket of water before being added to the 1000 L tank full of water or supplied through a venturi system. In a venturi set-up, the fertilizer is mixed in a separate, smaller tank and a venturi injector is used to connect the fertilizer tank to the pure water pipe that goes into the greenhouse. The venturi injector operates on the principle that pressure drops accelerate the change of velocity of the water as it passes through the constriction [22].

7.2.1 Fertilizer compatibility

Two or more soluble fertilizers can be mixed in the same water and supplied to the plant provided they are compatible (Figure 3). For example, calcium fertilizer reacts with phosphate fertilizer to form a precipitate which blocks the emitters of the drip lines. This prevents the plants from getting water. Also, there should be no physical segregation of the components. As such it is always advisable to have two tanks in each tunnel: one aptly labeled for fertilizers that contain calcium or magnesium, and the other for those fertilizers that contain phosphorus or sulfur [24].

Figure 3.

Water-soluble fertilizer compatibility chart [23].

Where two tanks are not available, there should be a standing rule that fertilizers should not be mixed except the agronomist is present. Water-soluble fertilizers are mixed with the irrigation water depending on the fertigation program adopted.

7.3 Pruning

In greenhouse tomato production, the quality of the fruit is as important as the quantity of the yield gotten. That is, the greenhouse market prefers big, clean, and sweet fruits with higher Brix. As such, instead of allowing the growth of several branches that produces more flowers and consequently more fruits, the plant is pruned early giving fewer but bigger fruits. The tomato plants are pruned to a single stem for best production by removing all lateral shoots commonly referred to as “suckers.” Suckers are the buds that emanate from the node. Usually, one sucker will form at the inner angle of the point where the leaf petiole attaches to the main stem. If the suckers are not removed, they will grow into new stems, and produce more flowers and consequently fruits. The fruits, though plenty, will be small in size and poor in quality which is not desirable for the greenhouse market. Preferably, desuckering (which is the process of removing the suckers) is carried out to maintain one main stem. The fruits, though fewer in number, will be larger, of higher quality, and command premium prices in the market. The practice of desuckering is usually done once per week, continuously, throughout the life cycle of the plant. In the process of removing the suckers, one or two top-most suckers at the shoot tip are left temporarily. One of them will be retained to continue the plant growth if the terminal of the main stem breaks.

7.4 Cluster thinning and fruit pruning

The purpose of fruit pruning is to increase fruit size and fruit quality and to balance fruit load. It also helps to maintain uniformity in fruit size. Distorted or undersized fruits at the end of each cluster are removed early because they are not desirable for the market and will reduce the size of the other good fruits in the cluster. Sometimes the clusters are generally pruned to the four proximal fruits. The decision to prune the clusters depends on the cultivar, that is, what is the expected fruit size and the number of fruits usually formed on a cluster of the variety. Also growing conditions and the market size preference are other factors that determine if to prune the cluster or not.

7.5 Staking and trellising

Staking is done 2–3 weeks after transplanting. For a distance of 2.5 m between the top and bottom binding wires, the twines should be cut into lengths of 3 m each. The twine is tied to the top and bottom binding wires and wound around the stem to keep the plant standing. The twine is made taut by tying it into a loop in the middle. As the plant grows taller, the loop is adjusted and wound around the newly grown shoot.

7.6 Application of fruit-setting solution

Pollination of the female flower part must occur before the fruit will set. Whatever prevents effective pollination reduces the number of fruit set per plant. Poor pollination could result in deformed fruit, smaller fruit, and fruit that is rough along the tops. Several factors, such as extreme temperatures, high humidity, drought, toxicities, nutrient deficiencies, and lack of pollen transfer, can cause poor pollination [25]. Pollination in greenhouse tomatoes is enhanced by the use of a fruit-setting solution. This operation starts when the plant starts flowering. The solution is diluted with water at 2 ml/L inside a spray bottle and sprayed directly into the flowers one by one. This is done twice weekly.

7.7 Defoliation

Defoliation is the removal of old and lower leaves. Usually, the old lower leaves are unproductive. Removing them reduces the number of sinks and allows more nutrients to be channeled to the fruits making them bigger and more qualitative. After every harvest, all the leaves below the last fruit at the lower part of the plant are cut. The lower leaves are detached up to the first fruit ground-up. A fungicide spray (copper or mancozeb preferably) should always follow every defoliation.

7.8 Cleaning of irrigation filter

The filter attached to the tank helps to sieve dirt from the irrigation water before it gets to the drip line. It is important to clean the filter frequently so that dirt will not accumulate in the drip lines.

7.9 Flushing

Occasionally, the emitters on the drip lines get blocked due to the dirt that passes through the filter. So, the end cap of the drip lines is removed and water is released to flush out the dirt every 2 weeks.

8. Environmental control

Computers are used to control environmental factors, such as temperature, relative humidity, light intensity, and CO₂ concentrations due to their capacity for automation and ease of use. They provide records of the history of the crop and its environment over time and alert operators to malfunctions in the greenhouse (greenhouse tomato production). Computers can control many mechanical devices within a greenhouse (vents, heaters, fans, evaporative pads, CO₂ burners, irrigation valves, fertilizer injectors, shade cloths, and energy-saving curtains) based on preset criteria, such as temperature, irradiance, humidity, wind, and CO₂ levels. Also, they can collect data from different sensors and process it. This capacity of the computer is called artificial intelligence. The computer uses the result to regulate the inner temperature or humidity of the greenhouse. The use of a computer to control the environmental factors makes it easier to balance plant growth [26, 27, 28]. Control of irrigation and fertilizer application regimes based on environmental conditions can also be computerized.

8.1 Relative humidity

In the greenhouse, humidity is a result of a precarious balance among the following: crop transpiration, soil evaporation, condensation on the greenhouse cover, and vapor escape due to ventilation. Vapor pressure deficit (VPD) affects transpiration and relative humidity. It changes as the ambient temperature changes. That is when there is low humidity and high temperature, the VPD increases resulting in increased stomatal resistance and consequently transpiration. Likewise, low VPD causes a reduction in plant transpiration that eventually results into dehydration, wilting, and necrosis [29, 30].

When the relative humidity is low, water is supplied by irrigation. However, high humidity encourages the proliferation of diseases. Generally, high relative humidity supports growth and enhances fruit setting, but if not managed, can cause water to condense on the leaf surface and lead to disease development [31].

There are limitations to the effectiveness of computers in controlling relative humidity. For example, humidity levels changes as vents are opened and closed to control temperature [32]. If the humidity goes higher than recommended and the temperatures remain at the normal level, the heating and ventilation systems should be adjusted to maintain acceptable levels of humidity and temperature. In glasshouses that have vents, the heating system should be turned on and the vents opened. In houses with fans, the fans should be turned on for a few minutes, and then the heater turned on to maintain air temperature. Venting for humidity control is most effective when the outside air is significantly cooler and drier than that inside the greenhouse. As the cool, dry air heats up in the tunnel, it absorbs the atmospheric moisture, which results in lower humidity. When the outside air is humid, venting can still be used to effectively control the relative humidity so far, the outside air is cooler than the inner air. However, practically, the cost of ventilation is justified only when the air outside is cooler and drier than the air inside.

8.2 Temperature control

The ambient temperature in the greenhouse is the primary environmental factor that affects plant vegetative growth, flower cluster development, fruit setting, fruit development, fruit ripening, and fruit quality. The average temperatures both day and night influence the growth of the crop. Higher temperature encourages faster growth [12]. Cuong and Munehiro [33] established that higher cumulative temperatures flowers bloom faster. Although maximum growth is known to occur at a day and night temperature of approximately 25°C, maximum fruit production is achieved with a night temperature of 18°C and a day temperature of 20°C (see Table 1). Hence, the recommended temperatures in Table 1 are a compromise and are developed to sustain high fruit productivity while maintaining a modest crop growth all through the season. The use of a shade net is advised (where sophisticated means are not affordable) to reduce the direct impact of sunlight and heat in hot areas.

	Germination	Plant raising	Transplanting	harvesting	Full harvest
Temperature (°)
Day	25	19–21	24	19	20–22
Night	25	19–21	24	19	17–19
EC (dS/m)	0.0–0.1	2.5–3.0	2.5–3.0	2.7–3.5	2.7–4.0
pH	5.8	5.8	5.8	5.8	5.8
Volume of feed (1/day)	—	0.2–0.3	0.2–0.3	0.5–1.5	0.5–2.5

Table 1.

Growing recommendations for tomato cropping [34].

8.2.1 Maintaining optimal temperatures

Optimal day and night temperatures for different crop developmental stages are important. As temperatures increase within the range of 10–20°C, there is a direct linear relationship between increased growth and development. If daytime temperatures are warm, night-time temperatures can be allowed to fall to conserve energy as long as the mean temperature remains in the optimal range.

8.3 Light

Light is a prerequisite for plant growth. Photosynthesis, which produces plant matter, can only take in the presence of light. The chlorophyll present in the green parts of the plant, especially leaves, uses light energy to fix atmospheric carbon dioxide with water to produce carbohydrates. Generally, the rate of photosynthesis is related to light intensity [35]. The value of light in tomato production is seen when it is not adequate. At low light intensities, flower bud development is inhibited and flowers fail to set into fruits. This is because the plant is unable to produce adequate sugar and carbohydrates needed for bud, flower, and fruit formation from the low levels of radiant energy. Not only do the poor light conditions limit photosynthetic productivity but the limited carbohydrates produced during the day are expended by the respiring plant so that it can survive through the long nights [36]. Generally, increased natural light intensity benefits the tomato plants, especially when adequate water, nutrients, and carbon dioxide are made available to the plant and the air temperature is prevented from becoming too high.

8.4 Carbon dioxide

As ventilation is not needed during cold weather, a carbon dioxide concentration of 1000 ppm is recommended during the day. During summer, however, when ventilation is essential, supplementing with 400 ppm carbon dioxide is economically useful in other countries [37]. Regions with a moderate (sea) climate are more likely to benefit from carbon dioxide applied in the summer, while the procedure is uneconomical in regions that have continental climates [38].

8.5 Air movement

Horizontal air movement is beneficial for several reasons. Approximately 1 m/s airspeed, which causes leaves to move slightly, is beneficial [39]. It helps to minimize the air temperature gradients across the greenhouse by blowing the moisture under the foliage and distributing it to the other parts of the greenhouse. The motion also brings down the carbon dioxide from the top of the greenhouse into the leaf canopy where it is utilized for photosynthesis and may assist in pollination [40]. Air movement improves the uniformity of the greenhouse environment and this enhances crop productivity and energy conservation.

9. Pest and disease management

Pest and disease incidence is generally low in a greenhouse farm. The ones to watch out for are bacteria wilt, nematode, Tuta absoluta, thrips, mites, blossom end rot (BER), and early and late blight. Control is by integrated pest management.

The soil is sterilized to reduce the spread of soil-borne diseases (bacteria wilt and nematode), while it is eliminated in soil-less culture. The most damaging tomato disease is bacteria wilt (Rastolnia solanacearum). When tomatoes are grown in the soil, a combination of chemical soil treatment, soil solarization, and use of tolerant varieties are used to manage the bacteria wilt [41].

Insects such as Tuta absoluta, locusts, and crickets are absent in glasshouses and screened out in tunnels that are covered on the sides with a net. Sticky papers are also hung in the tunnel to trap insects. IPM program is desired for pest control.

BER is a physiological disorder that results from inadequate calcium at the blossom-end of the tomato fruit. Calcium as an immobile element in the phloem needs to be managed before the deficiency symptom becomes evident [42].

10. Harvest and storage of tomato fruits

Generally, the harvesting starts about 75 days after transplanting. There are three stages of fruit ripening (Table 2). The market patronizing greenhouse tomatoes prefers fruits harvested at the breaker stage or pink. The fruits are carefully plucked from the plant and placed in the basket. The baskets are taken to the sorting room where they are graded according to their colors. The pink fruits are labeled Grade A, while the red ones are categorized as Grade B. Cracked tomatoes are removed and labeled Grade C after which they are all taken to the cold room where they are stored.

Stage	Description
Breaker	Red stains appear on fruit skin
Pink	Tomato turns pink, not yet ready for consumption
Red	The tomato is red and completely ripe for consumption

Table 2.

Stages of fruit ripening [43].

11. Conclusions

Tomato is a perishable vegetable fruit, which makes it difficult to preserve. Also, it is difficult to grow tomatoes in the rainy season due to the proliferation of diseases. Hence, the reason for the high market demand. Through the provision of ideal climatic conditions needed for optimal growth and possible output of any tomato variety planted, greenhouses offer a dependable alternative to growing high-quality tomatoes both in and out of season. The chapter makes it easier for a tomato farmer, an individual, or an entrepreneur who is interested in starting or expanding a tomato production firm to understand the fundamentals of greenhouse tomato production.

Acknowledgments

The authors would like to sincerely thank Ibrahim Sheikh of Dobi Agri Nig Ltd for reviewing the manuscript before it was submitted to the publishers and for the image in Figure 2.