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RESPONSE OF Jatropha curcas L. TO FUNGAL PATHOGENS IN SOUTHWESTERN NIGERIA

ABSTRACT

Cultivation of Jatropha curcas L. for production of biodiesel as an alternative source of energy is crucial for sustainable development in Nigeria. Pests and pathogens especially fungi have been reported to be a major constraint to commercial cultivation of J. curcas in Asia and some West African countries. However, this is yet to be fully investigated and documented in Nigeria. Fungal pathogens infecting J. curcas in southwestern Nigeria were therefore investigated.

Two hundred plant samples were randomly collected from each of Ekiti, Lagos, Ogun, Ondo, Osun and Oyo states, Nigeria. Fungi were isolated from these samples and the isolates were identified using standard procedures. Pathogenicity tests of these organisms (n=12) were carried out on five J. curcas accessions (Ex-Basirika, Ex-Mbatdiya, Ex-Misau, Ex-Ibadan and Ex-Kano) in the screenhouse using Koch‘s postulates. The experiment was laid out in a Completely Randomized Design (CRD) with four replicates. The accessions were also grown for three years on the field in Randomized Complete Block Design (RCBD) layout with four replicates. Data were collected on occurrence of fungal organismsDisease intensity (incidence and severity) were recorded at weekly intervals for 16 weeks after inoculation. Field evaluation of disease incidence (%) and severity (1-5, ranging from no disease to highly susceptible) was carried out at three months interval for three years. Data were analysed using descriptive statistics and ANOVA at a0.05.

Anthracnose, mildew, canker, dieback, fruit and root rots were common symptoms found on J. curcas in southwestern Nigeria. Colletotrichum gloeosporioides was the highest occurring fungal species in all the states with the highest occurrence (26.0 %) in Ekiti. Oidum jatrophae was the lowest with the least occurrence (7.1 %) in Lagos state. Colletotrichum gloeosporioides, Curvularia lunata, Fusarium oxysporum, Oidum jatrophae and Lasiodiplodia theobromae among the isolated fungi were pathogenic on Jatropha curcas in the screenhouse experiment. Reactions of the accessions to fungal diseases showed significant variations in disease incidence and severity. Susceptibility of accessions was in the order: Ex-Ibadan > Ex-Kano > Ex-Mbatdiya > Ex-Basirika > Ex- Misau (61.4 % > 59.5 % > 43.4 % > 37.4 % and > 28.3 %, respectively). Anthracnose was

the most prevalent disease encountered, with maximum incidence in the screenhouse (26.6

%) and on the field (95.7 %). Disease intensity for Colletotrichum leaf anthracnose, L. theobromae collar rots, Cankers, Oidum mildew, shoot dieback and  F. oxysporum root  rots was 59.7 %, 26.5 % , 16.4 %, 41.9 %, 43.1 % and 38.9 % respectively.

Five pathogenic and seven non-pathogenic fungi were isolated from Jatropha curcas in southwestern Nigeria. Colletotrichum gloeosporioides was the major isolated fungal pathogen and was the most virulent on Jatropha curcas. Ex-Misau was tolerant and it is therefore recommended for intensive cultivation.

    CONTENTTABLE OF CONTENTS    PAGE
Title i
Abstract ii
Certification iv
Acknowledgements v
Dedication vi
Table of Contents vii
List of Tables xiii
List of Plates xvi
List of Figures xviii
1.0       CHAPTER ONE:INTRODUCTION1
2.0       CHAPTER TWO:LITERATURE REVIEW5

Jatropha oil                                                                                                      11

3.0.      CHAPTER THREE:  MATERIALS AND METHODS                         27

screenhouse and field  studies                                                                        29

3.3.2.   Pathogenicity test of fungal organisms isolated from J. curcas accessions    31

  1. Inoculation techniques used for pathogenicity screening of J. curcas

seedlings                                                                                                         31

and natural field infections                                                                             34

fungal diseases                                                                                                34

Sacc causing symptoms of anthracnose on J. curcas                                      38

with five J. curcas accessions collected from the gene-bank of  FRIN        43

isolated from J. curcas.                                                                                   70

Jatropha plants                                                                                                76

under different inoculation techniques

on J. curcas

J. curcas                                                                                                          80

Curvularia species.                                                                                                                              88

Control Counterparts                                                                                      92

  1. Anthracnose expression on J. curcas under natural infection                       
    1. Performance of five J. curcas accessions in the field under natural
    92

infection by C.  gloeosporioides                                                                     92

Jatropha accessions                                                                                        96

six and 12 months under natural field infection                                             96

field infection                                                                                                 100

powdery mildew infection                                                                              100

C. gloeosporioides in Two Field Locations at Ibadan South-West Nigeria   104

  1. Inoculum potential of C. gloeosporioides from Jatropha seeds in the field   104
    1. Performance of seedlings raised from three months stored J. curcas seeds 108
    2. Shape and growth rate of different Colletotrichum sp. isolated

from J. curcas                                                                                                 108

anthracnose on J.curcas.                                                                                108

planting trial    (2010)                                                                                     112

severities in four Jatropha accessions                                                              116

5.0.      CHAPTER FIVE:  DISCUSSION                                                            119

6.0.      CHAPTER SIX: SUMMARY AND CONCLUSION                              137

REFERENCES                                                                                              139

LIST OF TABLES

TABLES                                                                                                                    PAGE

J. curcas accessions                                                                                        45

  1. Incidence of canker on shoots of J. curcas accessions under natural infection 9 months after planting (MAP) in two locations                                               61
    1. Pathogenicity test of fungal isolates on J. curcas

79

curcas accessions at four weeks after inoculation 82

J. curcas accessions inoculated with Colletotrichum gloeosporioides             85

  1. Incidence (%) of leaf chlorosis (LC), leaf spot (LS) and leaf blight (LB) on J. curcas inoculated with Colletotrichum sp.                                                    86
    1. Root rot incidence on J. curcas accessions inoculated with

F. oxysporum in the screenhouse                                                                    87

90

C. gloeosporioides and Curvularia lunata at (12 WAI) 91

4. 15    Fresh plant weights of Jatropha accessions inoculated with C. gloeosporioides                                                                                                          93

4. 18 Resistance evaluation of J.curcas accessions for anthracnose resistance at 4, 8 and 12 months after planting                                                                                97

  1. Incidence of leaf chlorosis, shot–hole and defoliation on J. curcas

accessions at 9 months after planting in the field 98

99

101

  1. Incidence of grey mildew caused by Oidum sp. on Jatropha accessions under three observation seasons                                                                                102
    1. Incidence and severity of root rots on J. curcas caused by Fusarium oxysporum and L. theobromae  at three months after planting (MAP)                             103
    2. Disease incidence and severity scoring of shoot dieback caused by C. gloeosporioides on J.curcas accessions under natural

field infection.                                                                                                105

Oidum jatrophae after six weeks of flower initiation                                     106

4, 8, 12 and 16 weeks after planting (WAP)                                                  107

4. 27 Anthracnose expression on five accessions of J.curcas seedlings

raised from 12 weeks old stored seeds                                                          109

room temperature                                                                                            110

three locations (May- June, 2012)                                                                   114

J. curcas in wet and dry seasons of 2011 and 2012                                       117

LIST OF PLATES

PLATES                                                                                                                PAGE

2.1       Jatropha curcas plant 9 (a)     and fruits (b)                                                   6

4.1a     Initial stage of leaf spot showing (a) chlorotic spots; (b) necrosis

caused by C.   gloeosporioides                                                                       49

caused by C. gloeosporioides                                                                         50

C. gloeosporioides                                                                                          51

  1. Anthracnose disease on J.curcas leaves caused by (a)

C. gloeosporioides and (b) C. lunata                                                              53

C. gloeosporioides                                                                                          54

(14 days after inoculation)                                                                             55

57

J. curcas shoot due to Colletotrichum invasion                                              58

60

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