ABSTRACT
The fungitoxic properties of ethanolic and aqueous leaf extracts of Azadirachta indica and Ocimum gratissimum used for the control of post-harvest fungal diseases of Solanum melongena were tested in vitro with benlate serving as the standard fungicide and water as the bank control. Three fungal species, Aspergillus niger, Rhizoctonia solani and Mucor ramosissimus were isolated from diseased S. melongena fruits kept at room temperature on laboratory tops for10 days. The fruits started showing signs of decay after 4 days of exposure. Growth on the fruits at the sites of the rot suggested the presence of fungal pathogens. Isolation and culturing of these pathogens gave the identified species as the causal agents. Pathogenicity test confirmed them as the causal organisms of the fruit rot. The three pathogens were treated with both ethanol and aqueous leaf extracts of the two plants at concentrations ranging from 25 to 100% and benlate at concentrations between 2.5 and 10.0%. Various concentrations of the extracts were added to prepared Potato Dextrose Agar (PDA) media. The pathogens were inoculated separately into the PDA media and were incubated for eight days. Fungitoxic effects of these extracts on the mycelial growth of the pathogens were significant at P ≤ 0.05 for all treatments. The three pathogens were completely inhibited by the two plant extracts for both the aqueous and ethanolic extracts at 100% concentration. With respect to ethanolic extract, O. gratissimum was more efficient than A indica, but the reverse was the case with aqueous extracts. Ethanolic extracts were generally more effective than the aqueous extracts. Ethanolic leaf extract of O. gratissimum may be used to effectively control post-harvest fungal diseases of S. melongena.
TABLE OF CONTENTS
Title Page
Table of Contents
List of Tables
List of Figures
List of Plates
Abstract
CHAPTER ONE: Introduction
1.1 Aim and Objectives of the Research
1.2 Statement of the Problem
CHAPTER TWO: Literature Review
2.1 Botany of Neem Plant (Azadirachta indica A. Juss)
2.2 Phytochemicals of neem plants
2.3 Botany of Scent Plant (Ocimum gratissimum) L.
2.4 Phytochemicals compositions and economic uses of O. gratissimum
2.3 Benlate (Fungicide)
CHAPTER THREE: Materials and Methods
3.1 Source of Materials
3.2 Sterilization
3.3 Method of Extraction
3.4 Preparation of Culture Media
3.5 Isolation of Fungal Isolates
3.6 Identification of Fungal Isolates
3.7 Pathogenicity Test
3.8 Determination of Percentage Frequency of Fungal Occurrence
3.9 Disease Severity Rating
3.10 Measurement of Radial Growth of Isolates in the Growth Media
3.11 Mycelial inhibition
3.12 Experimental Design
3.13 Statistical Analysis
CHAPTER FOUR: Results
4.1 Characteristics of Fungal Isolates
4.2 Percentage Frequency of Fungal Occurrence
4.3 Disease Severity Rating
4.4 Effects of Azadirachta Indica Extracts and Benlate Solutions on Pathogens at Various Contrations
CHAPTER FIVE: Discussion
5.1 Conclusion
5.2 Recommendations
REFERENCES
CHAPTER ONE
1.0 INTRODUCTION
Garden egg (Solanum melongena Linn) of the family Solanaceae (Obeng-Ofori et al., 2007) is a kind of fruit that is very important for man; as food, supplying some major nutrients, and as a source of bioactive ingredients militating against some diseases like diabetes mellitus and liver problems. It is also used for many other purposes among which are to achieve weight control within a short period, eliminate unnecessary salts in maintaining proper functioning of the heart, reduce the sugar content level in diabetics because of its low calorie and high fibre contents and reduce blood cholesterol (Aliyu, 2006). However, the damage caused by pests and microbes often constitute a great impediment to biomass productivity of this plant. It is for example susceptible to fungal diseases caused by Phytophthora nicotianea, var. parasitica and if the fruit touches the ground, Corticium rolfsii will cause an infection (Obeng-Ofori et al., 2007). This has stimulated the search for suitable control strategies against the disease.
Garden egg (Solanum melongena Linn) is commonly referred to as “igba” or”ikan” among the Yoruba, “yalo” among the Hausa and “aňara” in Igbo language. It is a fruit native to India. Today, it is cultivated in many parts of the warmer regions of the world, Africa inclusive. The fruit is often shaped like an egg hence the name garden egg and comes in different colours like green, white, grey or a combination of these colours (Osei et al., 2010). It tastes from bland to sweet or slightly bitter. The over ripped ones are used to make stew, and the stew made with garden egg is palatable. The fruits and leaves are used as vegetables, while the fruits serve as ‘kola’ in ceremonies.
Nutritionally, the fruit when mature for consumption contains 92.7% water, 4% carbohydrates, 1.4% proteins, 1.3% fibre, 0.3% fats, 0.3% minerals and is rich in vitamins A and B. It was reported by Shukla and Naik (1993) that on the average, the oblong-fruit
Many fruits and vegetables are perishable especially in tropical and subtropical regions without adequate refrigeration. The magnitude of post-harvest losses in fresh fruits and vegetables is estimated at 25.8% (Thirupathi et al., 2006). Most of the product is lost after the harvest because of inadequate handling and preservation methods. People in developing countries often cannot afford the use of cold storage facilities, which may be because of lack of capital or lack of technical knowledge by small scale growers and retailers in these areas (Thirupathi et al., 2006). Fungi are the most important and prevalent pathogens infecting a wide range of host plants, causing damage to the fresh fruits and vegetables during storage and transportation and subsequently economic loss. Various strategies that have been used to control the pathogens include the use of chemical and biological agents. Some notable synthetic chemicals have been developed and used to control these diseases. However, they have been reported to be toxic to both plants and mammals (Chaturvedi et al., 2003), and they are expensive to peasants and subsistent farmers......
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