Tomato production

Area under crop:

Tomato is the most popular vegetable crop grown all over the country. Both wet and dry season cropping contribute immensely to the national requirement, but the bulk of production is from the dry season cropping particularly under irrigation in the Northern states and near perennial river banks in the Southern States. Production of tomato in Nigeria is concentrated in the guinea savannah due to the optimum climatic conditions for itss production within the ecology. Some part of the guinea savanna ecology, particularly Benue State unfortunately are unable to produce enough tomato for local consumption due to non-availability of improved planting materials. The available local variety in production has low fruit yield, with poor quality fruits yield, with poor quality fruits, short shelf life due to very high water content of the fruits and high susceptibility to insect pest and diseases. Tomato in addition is also cultivated in dthe semi-arid region during the cool dry dry season using irrigation.

Soil testing and seed:

This involves testing for the soil if it has the nutrient availability need by the crop. There are several seed companies in Nigeria where quality and hybrid tomato seeds can be bought which are:

• The Seed Project Company Ltd a private company in Kano established in 2005.
• Genesis Seed Ltd . The following varieties of tomato are available: Shani, tamar, ella, lola, alegra, deli, betty, perla, sarina, esterina, cuore di bue, marmand, yellow perfection, Burbank,
• Maina Seeds Ltd. sells improved tomato seed to farmers such as UC82B and Romavf,

Climatic and Soil requirements:

Tomato is a warm season crop that is sensitive to frost. An average daily mean of 20 to 24 C is optimum for growth, yield and fruit quality. Fruit set and quality are poor at temperatures below 12 and 35 C. Hot, dry winds cause excessive flower drop while continuous moist, rainy weather conditions result in the occurrence and spread of foliar diseases. It is therefore recommended that tomatoes be grown in dry areas under irrigation. Soils should be rich in organic matter and plant nutrients, with a Ph value of 6 to 7. It has been discovered that tomato, when grown in well-managed sandy loams and heavy clay loams free of hardpan gives a good result but best results are obtained in deep, well-drained loams. The soil should be rich in organic matter and plant nutrients, with a pH value of 6 to 7.

Varieties of tomatoes:

There are about 7500 tomato varieties worldwide. The varieties of tomato can be local or hybrids which varies from one region to another.  The hybrid tomato varieties in south-western part of Nigeria include DT97/162A(R), DT97/215A, Tropical, Roma VF, UC82B etc. The hybrid tomato varieties in Northern part of Nigeria include Lindo, Jaguar, Roma Savana VF, etc. The hybrid tomato varieties in Eastern Nigeria part of Nigeria include Lindo, Jaguar, Roma Savana VF, etc.

Planting:

Seedlings should be raised in beds 1 – 1.5m wide, and as long as necessary (about 10m). for good seedling emergence and establishment, nemagon 20 should be applied to control soil nematodes. It should be put into the soil at 7g/m² and the granules incorporated into the seed bed to a depth of 15 – 20 cm. Farenox may also be used at 3 -4 in 1,100 litres of water per ha-1 at 2weekly intervals. For most varieties, double row of 45 x 60 cm spacing is recommended.

Management practices:

Nutrient deficiency symptoms:

Nitrogen deficiency: leaves are light green lower, lower leaves turn yellow and dry up veins become deep purple; stems are hard and purple, flower buds turn yellow and drop

Phosphorus deficiency: leaves are olive green: foliage is sparse; plants are stunted; stalks are slender and may show necrotic areas in extreme cases. Fruit ripens unevenly and lacks solidity

Potassium deficiency: lower leaves become yellowish or greyish-green along margins and at tips, followed by necrosis, dead areas turn brown giving the lower part of the plant a bronzed appearance.

Fertilizer application:

wherever possible, farm yard manure should be used up to 25 tonnes/ha. The recommended fertilizer programmes for tomato are shown below

Methods and time of application:

Nursery- the compound fertilizer 15-15-15 or any alternative should be applied to the seedbed at the rate of 25kg. the fertilizer should be worked into the soil and seed bed gently consolidated. The surface should be raked to leave a fine tilth. If poor growth of seedlings is observed, there may be need for addition of nitrogen fertilizer.

Field- the recommendations are summarized in the table below. Application of combination of farm yard manure and inorganic fertilizers is recommended during land preparation.

Weed control- apply metribuzin (sencor) at the rate of 1.5 – 2.0 kg per hectare at the time of transplanting. Mixtures of metri buzin with diphenamid, metolachlor or alachlor without supplementary hoe – weeding.

Chemical control- Apply fungicides sprays of very low volume (VLV). Although lines with resistance to septaria have been identified of which T420 has been the most outstanding

Yield expectancy-

Farmers obtain about 6t/ha of fresh tomatoes. Under improved management, yields up to 30t/ha are obtainable under irrigation, while up to 15t/ha are obtained under rain fed conditions.

Cultural practices-  successful production of tomato involves both nursery and field management. The seeds are usually sown in the nursery and later transplanted into the field to facilitate a good field establishment. Both the wet and dry season productions are feasible provided irrigation water is not limiting in the dry season which produces the best crop due to limited pests and disease infestation

Post-harvest handling:

Tomato is a perishable crop and as a result has a short shelf life of about 48 hours under tropical conditions owing to it high moisture content. Specialised postharvest handling practices and treatment methods are needed in order to extend the shelf life of the crop after harvest. Failure to adhere to these specialised handling practices and treatment methods will result in high amount of loss. Losses of up to 50% can be recorded in tomatoes between the harvesting and consumption stages of the distribution chain in tropical countries.

Post handling steps:

Harvesting:

Care must be taken during harvest of tomato fruits in order to attain the best quality as the physiological maturity of any fruit at harvest has an important effect on post-harvest quality of that fruit. Harvesting of fruits should be done in either early or late hours of the day to avoid excessive field heat generation and to reduce losses in tomato production. The inability of producers to follow these simple but vital harvesting procedures coupled with some inefficiencies (like lack of ready market and processing facilities) in the entire value chain may explain the reasons why there are lots of losses in tomatoes harvested at fully ripened state in most developing countries.

Precooling after Harvest

Field heat is usually high and undesirable at harvesting stage of tomato fruits and should be removed as quickly as possible before any postharvest handling activity. Excessive field heat gives rise to an undesirable increase in metabolic activity, therefore, immediate cooling after harvest is important. Precooling minimizes the effect of microbial activity, metabolic activity, respiration rate, and ethylene production, whilst reducing the ripening rate, water loss, and decay, thereby preserving quality and extending shelf life of harvested tomatoes. The suitable temperature ranges of about 13–20∘C for tomato handling can be attained either in the early hours of the morning or late in the evening. Harvested fruit must be precooled to remove excessive field heat if harvested at times other than the recommended periods. A cheap but effective way of precooling harvested tomatoes for producers of developing countries can be by dipping fruits in cold water (hydro cooling) mixed with disinfectants such as Thiabendazole and sodium hypochlorite if availability of clean water is not a challenge. This method is effective in removing field heat whilst reducing microbial loads on the harvested fruits.

Cleaning or Disinfecting.

Proper hygiene is a major concern that must be considered during handling of vegetables like tomato, not only because of its postharvest diseases, but also because of incidence of food-borne illnesses that can be transmitted to consumers. Unfortunately, cleaning or disinfecting tomatoes after harvest is not a common practice for most tomatoes handlers in developing countries especially those from Africa. This practice may be attributed to either the unavailability of portable water at the production sites or the sheer ignorance of the practice.

However, in places where water is not a constraint, post-harvest and food borne diseases in fruits and vegetables can be reduced by the use of disinfectants in water either for washing or for cooling. The use of various disinfectants during postharvest treatment of tomatoes is well documented. For instance, sodium hypochlorite solution has been used to sterilize tomato fruits in order to reduce the incidence of fungal infection before any postharvest treatment was applied. Dipping of tomato fruits in thiabendazole solution reduced the microbial load on the fruits. Fruits and vegetables are usually treated with chlorinated water after washing to reduce the microbial load prior to packaging.

Sorting and Grading.

One of the most important processes in packaging and marketing of fruit and vegetables is sorting and grading. Sorting is the removal of rotten, damaged, or diseased fruits from the healthy and clean ones. The damaged or diseased fruits can produce ethylene in substantial amounts which can affect the adjacent fruits.

Grading: It is also a process of categorising tomato fruits on the basis of colour, size, stage of maturity, or degree of ripening. The two processes are vital in maintaining postharvest shelf life and quality of harvested tomatoes. Sorting limits the spread of infectious microorganisms from bad fruits to other healthy fruits during postharvest handling of tomatoes. Grading also helps handlers to categorise fruits and vegetables in a given common parameter which enables easy handling.

For instance, grading on the basis of colour or maturity stage will help eliminate overripe fruits which will easily produce ethylene to hasten the ripening process in the whole batch. Commercial tomato producers normally use sophisticated systems that require precise sorting and grading standards for their produce. Small-scale producers and retailers in developing countries in contrast may not use written down grading and sorting standards; however, the produce must still be sorted and sized to some degree before selling or processing it.

Packaging.

Packaging is also one of the important aspects to consider in addressing postharvest losses in fruits and vegetables. It is enclosing food produce or product to protect it from mechanical injuries, tampering, and contamination from physical, chemical, and biological sources. Packaging as a postharvest handling practice in tomato production is essential in putting the produce into sizeable portions for easy handling. However, using unsuitable packaging can cause fruit damage resulting in losses. Some common packaging materials used in most developing countries include wooden crates, cardboard boxes, woven palmbaskets, plastic crates, nylon sacks, jute sacks, and polythene bags.

Most of the above mentioned packaging materials do not give all the protection needed by the commodity. Whilst the majority of these packaging materials like the nylon sacks do not allow good aeration within the packaged commodity causing a build-up of heat due to respiration, others like the woven basket have rough surfaces and edges which cause mechanical injuries to the produce. The wooden crate and the woven palm basket are some of the common packaging materials used in many developing countries especially those in Africa for packaging tomatoes. The major shortcoming of the wooden crate is in its height which creates a lot of compressive forces on fruits located at the base of the crate. These undesirable compressive forces cause internal injuries which finally result in reduced postharvest quality of the tomatoes.

Storage:

Tomato has very high moisture content and therefore is very difficult to store at ambient temperatures for a long time. Meanwhile, storage in the value chain is usually required to ensure uninterrupted supply of raw materials for processors. Storage extends the length of the processing season and helps provide continuity of product supply throughout the seasons.

For short-term storage (up to a week), tomato fruits can be stored at ambient conditions if there is enough ventilation to reduce the accumulation of heat from respiration. For longer-term storage, ripe tomatoes can be stored at temperatures of about 10–15∘C and 85–95% relative humidity. At these temperatures, both ripening and chilling injuries are reduced to the minimal levels. These conditions are also difficult to obtain in most tropical countries and therefore losses of appreciable quantities of harvested tomatoes have been reported.

This is consistent with the claim that the quality of tomato is compromised when exposed to high temperatures and high relative humidity. Very low temperature storage too is detrimental to the shelf life and quality of many tropical fruits like tomatoes. For instance, refrigerating a tomato will reduce its flavour, a quality trait of tomatoes which is largely determined by the total soluble solids (TSS) and pH of the fruit. An understanding of the correct temperature management during storage of tomatoes is vital in extending the shelf life of the fruit whilst maintaining fruit qualities.

Transportation.

In most developing countries, the production sites for many tomato producers are far from the marketing centres and also inaccessible by road. Transporting harvested tomatoes to the market on such bad road network and the lack of proper transportation like refrigerated vans become a big challenge for both producers and distributors.

During transportation, the produce should be immobilized by proper packaging and stacking to avoid excessive movement or vibration. Vibration and impact during transportation as a result of undulations on roads are one of the major causes of postharvest losses to most fruits and vegetables especially tomatoes.

The bad nature of road networks in most developing countries therefore provides these unfavourable factors during transportation resulting in great losses. The wobbling nature of most of the vehicles coupled with the bad nature of roads causes a lot of mechanical damage to the produce before it reaches its destination. Handlers from developed countries on the other hand use refrigerated containers and trailers which travel on reasonably good roads. Transporting tomatoes in refrigerated trucks is not only convenient, but also effective in preserving the quality of fruits. However, both the initial investment and the operation costs of these vehicles are very high and beyond the affordable reach of most producers in developing countries.

Even though handlers from developing countries may not have the capacity to use refrigerated trucks, they should be well educated on the consequences that any other transportation option they use may have on their produce.