1.0                                                 INTRODUCTION
Tomatoes are vegetables grown in the northern part of Nigeria. The word ‘tomato’ may refer to the plant (Solanum lycopersicum) or the edible typically red fruits that it bears. Tomato can be classified as follows:
Kingdom:       plantae
Order:             Solanales
Family:           Solanaceae
Genus:            Solanum

Species:         S.lycopersicum
Synonyms:Solanum lycopersicum L.(1753)
                        Lycopersicon (H.Karst, 1882).
The genus Lycopersicon, comprising nine (9) species, has its origin in the South American Andes, from Central Ecuador through Peru to Northern Chile. Tomatoes which can be planted in cool and dry regions are also grown at homes, in the garden and also commercially in the fields for sales, also tomatoes have many uses; they can be consumed raw or fresh in salads or cooked in sauces and also are used for flavoring in soups, stew and sometimes in meat and fish dishes. Tomatoes also can be used in wines. Economically, they are equally important are the processing forms such as purée, juice, ketchup and canned whole. Tomatoes are considered a vegetable for culinary purposes. The tomato vegetable is rich in lycopene which has beneficial health effects. Tomatoes are said to belong to the nightshade family.
Tomato plants have erect on prostrate stems up to 2-4m long, its’ taproot stretches up to 0.5m deep or more, with a dense system of lateral and adventitious roots. It has a weak stem that often sprawls over the ground and vines over other plants. It is said to be perennial in its native habitat, although often grown outdoor in the temperate climates as an annual crop. The world tomato production in 2001was about 105 million tons fresh fruit from an estimated 3.9 million hectare. Leading countries in tomato production are:
China   ------------------------------------------934,000ha
India     -------------------------------------------500,000ha
Turkey -----------------------------------------225,000ha
Egypt    ------------------------------------------181,000ha
USA     -------------------------------------------164,000ha
In 2001, world exports of fresh tomato fruits were estimated at 4million tons, valued at 300 million US dollars mainly from Spain, while Netherlands’ and Mexico with about 600 million US dollars. Also, the area used for tomato production in tropical Africa is about 300,000ha with an estimated annual production of 2.3million tons. Nigeria being the largest producer of tomato with 126, 000ha and an annual production of 879, 000 tons of fresh tomato. (World tomato production 2001)
There are about 7500 tomato varieties grown for various purposes around the world. Tomato varieties are roughly divided into several categories, based mostly on shape and size. Tomatoes are commonly attacked by pest and disease, such insect pest that attack tomato are: stink bugs, cutworms, tomato hornworms, tobacco hornworms, aphids etc.(Hahn and Fetzer 2009). When insects attack tomato plants, they the plant peptide hormone system in which activates defensive mechanisms such as the production of protease inhibitors to show the growth of insects (Narvaez and Cardenas 2008) the common diseases of tomato include: verticullium wilt, fusarium wilt, alternaria and root-knot nematode disease (Pleger et al 2008).
Tomatoes can and are easily infected by nematodes. When the roots of the plants are severely infected by the root-gall nematode, the normal root system is reduced to severely galled roots with a completely disorganized vascular system. Growth is retarted and leaves become chlorotic (Nestscher 1971). Meloidogyne attack causes 50-70% losses to tomatoes and approximately 5% of global loss in tomatoes and other vegetables (Sasser J.N 1989). Although 51 species of meloidogyne have been described to date (Jepson, 1987). Four (4) species of the meloidogyne are of particular economic importance.
These includes:-
Meloidogyne incognita
Meloidogyne javanica
Meloidogyne hapla
Meloidogyne arenaria(Luc et al 1990)
Also root-knot nematodes (meloidogyne spp) cause histopathological changes in root tissues of tomatoes. The results of these changes are the formation of giant cells and for galls in the root system. This abnormality can upset the normal physiological activities of the vascular tissues of the root system and may finally cause wilting, stunting ,leaf chlorosis and poor growth (Ekanayake et al 1938) The ability of Meloidogyne spp to infect their host depends on the factors such as initial nematode population ,plant varieties or cultivars (resistance or susceptibility), age of the plant host at the time of infection and nematode activity. Besides direct damage, root-knot nematodes serves as a predisposal agent in development of other disease. The disease complexes produced by interaction of nematode with pathogenic bacteria or fungi are more damaging to plants than these pathogen acting alone. (Siddiqui, 1998, Noel and Edward,1989). In certain situations, the nematode has been responsible for breaking disease resistance to fusarium wilt. Varieties of the same crop differ in their responses to root-gall nematode infection. Agu (2010) reported that the four landrace of Dioscorea rotundata exposed to Meloidogyne incognita infection differed in their galling responses to the nematode. Odihirin (1981) also reported some cowpea varieties: TVU 857 and 841 with natural immunity or tolerance to both Meloidogyne incognita and Meloidogyne  javanica. These reports are suggestive that crop varieties vary in their inherent genetic resistance status to root-gall nematodes. Little or nothing is known about the resistance/susceptibility statues of the commonly grown tomato varieties in Abakaliki agro-ecology to root-gall nematode infection. This study was therefore concerned with the evaluation of three (3) tomato varieties against root-gall nematode infection in Abakaliki Agro-ecology.
Specific objectives
1.         To ascertain the degree of susceptibility/resistance of the three (3) tomato varieties to meloidogyne spp.
2.         To investigate the effect of root-knot nematode on the three (3) tomato varieties
1.         To evaluate the susceptibility/resistance of three (3) commonly grown tomato varieties to root-knot nematode disease in Abakaliki Agro-ecology.
2.         To make recommendation/s based on the variety yield and susceptibility to root-gall nematode for possible adoption by farmers. There are no specific objects
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