THE EFFECT OF LEAF EXTRACT ON THE CONTROL OF ROT IN STORAGE YAM (Dioscorea species L.) (Azadirachta indica A.JUSS., Piper nigrum L., Vernonia amygdalina DEL. and Ocimum basilicum L.)

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