ABSTRACT

The control of yam rot in storage using the leaf extract of Azadirachta indica, Piper nigrum, Vernonia amygdalina and Ocimum basilicum. The experiment was conducted in the Laboratory Department of Plant Science and Biotechnology, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike, Using a Completely Randomized Design. The Yam tubers used were visually classified as having 40% nematode infestations and obtained from the Yam barn of National Root Crops Research Institute (NRCRI), Umudike, Nigeria. Four samples of fresh Yam were also collected from the barn for pathogenicity test. The plant extracts were diluted with tap water at the ratio of 1: 5 (1ml of plant extracts + 5 ml of water) respectively. 150 cl of tap water was thoroughly mixed with 10 ml of each diluted extracts in buckets and the infested yam were soaked for 24 hours. The Yam tubers were removed from the buckets while data on sprouting, Rot and Insects were recorded according to the method of Salawu. The proximate of evaluation of the treated and the untreated tubers were recorded in terms of Protein, Fibre, Fat, Moisture, Ash, and Carbohydrate contents. The pathogenic results shows that Fungi like Rhizopus, Penicillum, Aspergilus, Fusarium and B. theobrone were the identified rot organism. Sprouting of Yam, treated with different extracts showed that only A. indica ranged from 0.75 ± 0.500 – 1.0 ± 0.00. However the effect of extracts of P. nigrum, V. amygdalina and control had significant effect P < 0.05 on the sprouting of Yam tubers. From the means, control treatment ranging from 0.50 ± 0.58 to 0.75 ± 0.58 had the lowest sprouting rate. There was also a significant effect P < 0.05 of Water on the Yam rot. The rot affected the carbohydrate, Protein and Fat content of the Yam tuber. Generally the extracts had a strong advantage to the germination, pathogenicity and Nutritional content of Yam tubers in Storage.

TABLE OF CONTENTS

Title page i

Declaration ii

Certification iii

Dedication iv

Acknowledgements v

Table of contents vi

List of tables viii

Abstract ix

CHAPTER ONE

1.0 Introduction 1

1.1 Justification  2

1.2 Aims and objectives 3

CHAPTER TWO

2.0 Literature review 4

2.1 Yam (Discorea species) 4

2.2 Botany of yam 5

2.3 Yam rot 6

2.3.1 Classification of yam rot 6

2.3.2 Dry rot 6

2.3.3 Soft rot 7

2.3.4 Wet rot 7

2.3.5 Control of yam rot 7

2.4 Botanical control of post harvest biodeterioration in yam tubers 9

2.5 Ocimum brasilicum (scent leaf) 10

2.6 Azadirachta indica (neem plant)  11

2.7 Piper nigrum (uziza leaf) 13

2.8 Vernonia amygdalina (bitter leaf) 14

CHAPTER THREE

3.0 Material and methods 16

3.1 Study area 16

3.2 Plant materials 16

3.3 Source of yam tubers 16

3.4 Preparation of leaf extracts 16

3.5 Dilution of extract/treatment 17

3.6 Isolation of fungi 17

3.7 Characterization and identification of isolates 18

3.8 Fungi isolates 18

3.9 Pathogenicity test 18

3.10 Experimental design 19

3.11 Proximate test of yam tubers 19

3.11.1 Moisture determination 19

3.11.2 Determination of crude protein 20

3.11.3 Estimation of crude lipid 20

3.11.4 Determination of crude fibre 20

3.11.5 Determination of ash content 21

3.11.6 Carbohydrate determination 21

CHAPTER FOUR

4.0 Results 22

4.1 Effect of plant extracts on yam sprouting 22

4.2 Effect of leaf extracts on insect infestation 23

4.3 Effect of leaf extract on the rot of yam tubers in storage 24

4.4 Proximate analysis of treated yam tubers 25

4.5 Fungi isolated from rotten yam 26

CHAPTER FIVE

5.0 Discussion/conclusion 27

5.1 Discussion 27

5.2 Conclusion 29

References 30