ABSTRACT
A pot experiment were undertaken to ascertain possible mixed infection effects involving Meloidogyne incognita and Fusarium oxysporum on the growth and performance on a resistant and a susceptible tomato plant. The Baermann method of nematode extraction was also used in getting the nematodes and analysis of raw data was carried out. Results revealed that both treatment (single and mixed) caused reduction in the various growth parameter on the susceptible tomato plant which were significant different as compared to its control. Simultaneous inoculations of both pathogens caused high reduction in the growth parameters but were not significantly different from either of the pathogen alone resulting in an antagonism interaction. On the resistant tomato plant there were no significant different on the number of leaves as compared to its control. The mean galls rating were much lower on resistant tomato plant inoculated with nematode alone as compared to the susceptible tomato plant that’s has the highest gall rating. Simultaneous and sequential inoculation of pathogens for both plants followed this trend of decreasing order of mean galls rating; N+f, N+F and F+n, however, the dominance of one pathogen over the other was dependent on the rime of establishment of the pathogen. Tomato is consumed nearly in every housed hold in Benue State and Nigeria at large, owing to its high nutritive value and diversified use .The losses caused by these pathogens, however, can be averted through used of resistant varieties.
CHAPTER ONE
1.1 INTRODUCTION
HISTORY AND ORIGIN OF TOMATO
The word “tomato” comes from the Spanish tomate. It first appeared in print in 1595. A member of the deadly nightshade family, tomatoes were erroneously thought to be poisonous (although the leaves are) by Europeans who were suspicious of their bright, shiny fruit. It is edible, often red fruit/berry of the nightshade Solanum lycopersicum L. commonly known as tomato plant.
The tomato is native to western South America and Central America, is one of the world’s most widely grown and processed vegetable crop (Thompson and Kelly, 1957). The species originated in the South America Andes and its use as food originated in Mexico, and spread throughout the world following the Spanish colonization of the Americas. It was first domesticated in Mexico and Cater and introduce to the Europe by Spanish in 1531. Its many varieties are now widely grown, sometimes in greenhouses in cooler climates. Tomato is consumed in diverse ways, including raw, as an ingredient in many dishes, sauces, salads and drinks. It is botanically a fruit. It is considered a vegetable for culinary purpose but one exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to process in a water bath rather than a pressure cooker as vegetable require. This dispute of tomato as vegetable and fruit has led to legal speculation in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables, but not on fruits, caused the tomato’s status to become a matter of legal importance. United states supreme court settled this controversy on 10thof May 1893 by declaring that the tomato is a vegetable based on the popular definition that classifies vegetables by use, that are generally served with dinner and not dessert [Nix v. Hedden(149 U.S. 304)] .
The world dedicated 4.8million hectares in 2012 for tomato cultivation and the total production was about 161.8million tonnes and the average world farm yield for tomato was 33.6 tonnes per hectare in 2012 (FAOSTAT 2012). According to FAOSTAT, the top three producers of tomatoes (in tonnes) in 2012 are China, India and United States. China, the largest producer, accounted for about quarter of the global output, followed by India and the United States. For one variety, plum or processing tomatoes, California account for 90% of U.S. production and 35% of the world production (Hartz, etal.; 2012).
Villareal (1978) reported that tomato production being a labour intensive programme requires about 42,000 man-hours for one hectare production as compare to 24,000 man-hours estimated for growing on hectare of rice in Nigeria. Consequently a large-scale tomato production can bring about rapid socio-economic transformation particular in the rural economy (Nkiru Omeregie etal.; 2005). In Benue state, tomato production is limited to wet season with attendant shortage and high price during the dry season. The low production is attributed to high night and day temperatures which have a detrimental effect on tomato growth and fruits set and result in poor pollen formation and flower abortion leading to poor fruit yield. Irrigation is practise along rivers coast during dry season.
1.2 ECONOMIC IMPORTANCE
The economic and nutritional importance of tomato fruits to Nigerians cannot be over-emphasized. It provides a source of food for man and a major source of income for many farmers who cultivate them for fresh produce markets (Aluko, 1989). It is consumed in diverse ways by man such as raw, as an ingredient in many dishes, sauces, salads and drinks. According to Nkiru Omeregie etal. (2005), tomato is helpful in the development of rural agro-industries. Tomatoes contain the carotene lycopene, one of the most powerful natural antioxidants. In some studies, lycopene, especially in cooked tomatoes has been found to help prevent prostate cancer but other research contradicts this claim. Lycopene has also been shown to improve the skin’s ability to protect against harmful ultraviolet ray according to BBC news 28 April 2008 and has no effect on the risk of developing diabetes but may help relieve the oxidative stress of people who already have diabetes (Valero, Vidal Burgos etal.; 2011). A study done by researchers at Manchester and Newcastle universities revealed that tomato can protect against sunburn and help keeping the skin looking youthful (Maccrae, 2008). Tomato leaves, stem and green unripe fruit of the tomato plant contain small amounts of the toxic alkaloid tomatine (Mcgee, 2009). They also contain solanine, a toxic alkaloid found in potato leaves and other plants in the nightshade family (Barceloux, 2009). Tomato plants can be toxic to dogs if they eat large amounts of the fruits or chew plant material.
1.3 BACKGROUND OF THE STUDY
The fungi and root-knot nematodes are known to reduce growth and performance of tomato plant when they infect the plant singly. This in essence, necessitated this research on the mixed infection effects of Fusarium oxysporum and the Meloidogyne incognita on the growth and performance of susceptible and resistant tomato plant.
1.4 AIM OF THE STUDY
The aim of this study is to determine the mixed infection effects of Fusarium oxysporum and the Meloidogyne incognita on the growth and performance of susceptible and resistant tomato plant
1.5 RELEVANCE OF THE STUDY
Mixed infection effects of pathogens on the growth and performance of tomato plant is lacking or in fact not existent at present in Nigeria. Probably because, symptoms of infection are sometimes erroneously taken for other causes like nutrient deficiency, lack of moisture or worse still ignored (Idowu etal., 1990; Iheukwumere etal., 2007). One among the few studies on mixed infection effects are those of Iheukwumere etal. (1995,1996,2005,2007,2012). This studies by Iheukwumere as stated above however, dealt with other crops but not tomato. This in essence, necessitated this experiment to determine the mixed infection effects of Fusarium oxysporum and the Meloidogyne incognita on the growth and performance of susceptible and resistant tomato plant which will provide information on disease complexes in tomato crops in Nigeria. This will help to determined strategies to induce controls for prevention of these pathogens from invading and damaging our tomato crops and also bridging the information gap on the infection complexes of crops involving a nematode and a soil fungus, particularly tomato.
