1.1 Introduction
Cadmium (Cd), chromium (Cr) and lead (Pb) are the heavy metals of most concern because they can affect human health even in small quantities. Wa˚ngstrand et al. (2007) reported that application of nitrogen fertilizers containing ammonium-N may increase Cd concentrations in plants, even if the fertilizers do not contain significant levels of heavy metals. In addition, Atafar et al. (2010) were also observed that application of some non-heavy metal fertilizers can potentially increase concentrations of Cd, Cr, and Pb in plants.
Accordingly, determining the available forms of heavy metals in soils is an important approach to the soil contamination assessment, especially in greenhouse areas which have great impact on environment and human health due to intensive use of fertilizers and pesticides containing heavy metals. The intensification of agricultural soil use, and changes in farming practice, characterized by intensive application of fertilizers and pesticides may cause soil pollution by heavy metals in greenhouses (Nouri et al., 2008). Namely, many chemical products used in agriculture, especially nitrogen and phosphate fertilizers, contain certain amounts of heavy metals, as result of their production from minerals used as a source of these elements.
Although the low level of heavy metals in fertilizers and pesticides in one-time use do not pose any hazard of soil or plant contamination, their long-term use in food crops production, especially in greenhouse vegetable production, contributed to the accumulation of heavy metals in the soils and consequently in food crops (Huang and Jin, 2008). However, up to now, heavy metal concentrations of greenhouse soil in Bosnia and Herzegovina and its pollution problem have been studied very little, especially there is no systematical investigation of the dynamics of heavy metals in the greenhouse soil-plant system in intensive tomato production. Since the heavy metals have a long residence time in soils, it is very important to study the status of heavy metals in soil, and their influence on vegetable safety, and consequently human health.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Statement of the Problem
Tomatoes are an attractive cash crop for small scale farmers and provide potential source of employment to many rural and urban people. The tomato fruits have been marketed freshly picked from the field and is the best selling fresh market vegetable crop (AVRDC, 2006).
Despite the human need of tomato, damage as a result of post-bacteria spoilage micro-organisms has been of serious concern. Microbial decay is one of the main factors that determine losses and compromises the quality of the produce. The extent of the losses especially through microbial decay has not been quantified in most areas and on this has been quantified the result are short lived.
Periodic surveys may help to understanding the seventy of losses in a specific place and at a specific time. Estimates of post harvest losses in Benue State have of been established. Therefore, the study aims at establishing estimates of post harvest losses in Nigeria, identify pathogens involved in post a harvest decay of tomato fruits and evaluate ways of managing them using crude plant extracts.
Several kinds of synthetic fungicides have been successfully used to control the post harvest decay of fruits and vegetable (Adasaveg et al, 2009, Kanetis et al, 2002). However, there are three major concerns the increasing consumer concern over pesticide residues on foods which are toxic and caranogenic, predominance of fungicide resistance strains of fungi due to excessive use of fungicides.
1.3 Aim and Objectives of Study
The aim of the Study is to examine the Effect of Heavy Metal on the Growth to Tomato Plant (Lycopersicum). In achieving this aim, the following specific objectives were laid out as follows:
- To examine the concentration of total and available forms of heavy metals (Ni, Cr, Cu, Zn, Pb and Mn) in the greenhouse soils as well as the distribution of heavy metals in the different parts of tomato plants (Lycopersicum esculentum Mill.
- To evaluate the health risks of consumption of tomato or other vegetable crops grown on greenhouse soils is of great interest to producers and consumers.
1.4 Significance of the Study
This study provides important information on the current status, causes of post-harvest losses of tomatoes in Benue State and their management using crude plant extracts. The output is this study will be important in reducing tomato post-harvest losses by improving the efficiency of post-harvest handling due to better post-harvest management strategies. Natural plant products and their analogues have been foud as important source of agricultural bio-pesticides which serve as anti-microbial properties of the plant extracts (Cardelina, 1995), reported that plant are sources of natural pesticide that leads to new pesticide development.
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.5 Scope of Study
The study focuses on the Effect of Heavy Metal on the Growth to Tomato Plant (Lycopersicum) in Ekiti State University, Nigeria.
1.6 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
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