ABSTRACT
This research work was aimed at investigating the dosimetry of X-ray doses on two African yam bean (Sphenostylis stenocarpa Hochst ex A. Rich) accessions (Ikwuano and Akara), effects on different x-ray doses on the growth parameters. Seeds of the African yam bean accessions were arranged into six groups each into a brown envelope paper containing 25 seeds each. The first group served as the control whereas the other groups were bombarded with different x-ray doses (1, 2, 4, 6, and 8 MGy) respectively. The results of the dosimetry test showed that 8MGy recorded the optimum plant height curve on Akara while in Ikwuano, the optimum curve was 2 MGy. From the dosimetry test results, two dose ranges were chosen for further investigation. The effects of irradiation doses showed a significant increase in the number of leaves, plant height, leaf area, stem girth, number of branches, plant height and germination percentage of 2 MGy and 8 MGy of Ikwuano accession and 6 MGy and 8 MGy of Akara accession as compared with the control which recorded the lowest growth parameters. Among the doses, 2 MGy and 8 MGy respectively gave the highest effects. The present work has shown that irradiating African yam bean with X-ray were effective in improving the plant growth.
TABLE OF CONTENT
Title
page i
Certification ii
Declaration iii
Dedication iv
Acknowledgement v
Table
of contents vi
List
of tables ix
List
of plates x
List
of figures xi
Abstract xii
CHAPTER 1
INTRODUCTION 1
1.1 Background of study 1
1.2 Justification 2
1.3 Aim and objectives 4
CHAPTER 2
LITERATURE
REVIEW 5
2.1 The
Botany and Morphological Description of African yam bean 5
(Sphenostylis stenocarpa)
2.2 Taxonomy
of Sphenostylis stenocarpa 6
2.3 Synonyms
of African yam bean 7
2.4 Cytogenetics
of African Yam Bean 8
2.5 Geographical
Distribution and Wide Adaptability of African Yam bean 8
(AYB)
2.6 Intra-specific
Variability and Diversity within African Yam Bean 10
2.7 Agronomy of African Yam Bean 11
2.8 Pests and Diseases of African Yam Bean 12
2.9 Biochemical
Control Strategy for Some Economic Pests of Legumes 13
2.10
Dosimetry 14
2.11
Mutation Breeding for Crop
Improvement 14
CHAPTER 3
MATERIALS
AND METHODS 15
3.1
Study Area 15
3.1.1
Collection of Planting Materials 15
3.1.2 Irradiation of
Planting Materials 15
3.1.3 Experimental Design 16
3.1.4 Data Collection 16
3.1.5
Statistical Analysis 17
CHAPTER 4
RESULTS
4.1 Results 18
4.1.1 Dosimetry
Test 18
4.1.2
The Effect of X-ray Doses on Plant Height
(cm) of Akara Accession 22
4.1.3 The Effect of X-ray Doses on Plant Height
(cm) of Ikwuano Accession 24
4.1.4 The Effects of X-ray Doses on Number of
Leaves Per Plant in
Akara Accession 26
4.1.5 The Effects of X-ray Doses on Number of Leaves
Per Plant in
Ikwuanoccession 28
4.1.6 The Effect of X-Ray Doses on Leaf Area Per
Plant (cm2) in Akara Accession 29
4.1.7 The Effect of X-Ray Doses on Leaf Area Per
Plant (cm2) in
Ikwuano Accession 31
4.1.8 The Effect of X Ray Doses on Number of
Branches Per Plant in
Akara Accession 33
4.1.9
The Effect of X Ray Doses on Number of
Branches Per Plant in
Ikwuano Accession 35
4.1.10 The Effect of X-Ray Doses on Stem Girth (cm)
in Akara Accession 38
4.1.11 The Effect of X-Ray Doses on Stem Girth (cm)
in Ikwuano Accession
39
4.1.12 Effects of X-Ray Doses on Germination
Percentage (%) of Akara Accession
41
4.1.13 The Effects Of X-Ray Doses On Germination
Percentage (%) of
Ikwuano Accession 43
CHAPTER 5
DISCUSSION
AND CONCLUSION 51
5.1 Discussion 51
5.2 Conclusion 53
5.3 Recommendations 53
REFERENCES 54
APPENDIX
LIST OF TABLES
Table
4.1.2 Effects of X-ray doses on plant
height of the three Akara accession 22
Table
4.1.3 Effects of X-ray doses on plant
height of Ikwuano accession 24
Table
4.1.4 The effect of X-ray doses on
number of leaves per plant in Akara 26
Table
4.1.5 The effects of x-ray doses on
number of leaves per plant in
Ikwuano accession 28
Table
4.1.6 The effect of x-ray doses on
leaf area per plant in Akara 30
Table
4.1.7 The effect of x-ray doses on
leaf area per plant in Ikwuano accession 32
Table
4.1.8 The effect of X-ray doses on number
of branches per plant in Akara 34
Table
4.1.9 The effect of X-ray doses on
number of branches per plant in Ikwuano 36 accession
Table
4.1.10 The effect of X-ray on stem
girth in Akara 38
Table
4.1.11 The effect of X-ray doses on
stem girth in Ikwuano 40
Table
4.1.12 The effect of X-ray does on
germination percentage of Akara 42
Table
4.1.13 The effect of X-ray doses on
germination percentage of Ikwuano 44
LIST OF PLATES
Plate
4.1 Dose sensitivity test on Akara
showing root and stem length 21
Plate 4.2 Dose
sensitivity test on Ikwuano showing root and stem length 21
Plate 4.3 Akara
6 MGy at 10 WAP 48
Plate 4.4 Akara
2 MGy at 10 WAP 48
Plate 4.5 Akara
control at 10 WAP 49
Plate 4.6 Ikwuano
2 MGy at 10 WAP 49
Plate 4.7 Ikwuano
8 MGy at 10 WAP 50
Plate
4.8 Ikwuano control at 10 WAP 50
LIST
OF FIGURES
Figure 4.1 Responses of different X-ray doses on Akara plant height 19
Figure 4.2 Responses of different X-ray doses on Ikwuano plant height 20
Figure 4.3 Graphical representation of the effect of X-ray doses on the
plant
height
of Akara at 10 WAP 23
Figure 4.4 Graphical representation of the effect of X-ray doses of
plant height
of
Akara at 10 WAP 25
Figure 4.5 Graphical representation of the effect of X-ray doses on
number of
Akara on number of leaves at 10 WAP 27
Figure 4.6 Graphical representation at the effect of x-ray doses of
Ikwuano on
number of leaves at 10 WAP 29
Figure 4.7 Graphical representation of the effect of x-ray doses of
Akara on leaf area at 10 WAP 31
Figure 4.8 Graphical representation of the effect of x-ray doses of
Ikwuano
on leaf area at 9WAP 33
Figure 4.9 Graphical representation of the effect of X-ray doses of
Akara on number of branches at 10 WAP 35
Figure 4.10 Graphical representation of the effect of X-ray doses of
Ikwuano on
number ofbranches at 10 WAP 37
Figure 4.11 Graphical representation of the effect of X-ray doses of Akara
on
stem
girth at 10WAP 39
Figure 4.12 Graphical representation of the effect of X-ray doses of
Ikwuano on
stem girthat10WAP 41
Figure 4.13 Graphical representation of the effect of x-ray doses of Akaraon germination percentage 43
Figure 4.14 Graphical representation of the effect of x-ray doses of Ikwuano
on germination percentage 45
Figure 4.15 Clustered bar chat of 6 agronomic characteristics at different
exposures of
X-raydoses of Akara 46
Figure 4.16 Clustered bar chat of 6 agronomic characteristics at different
exposures of
X-raydoses of Ikwuano 47
CHAPTER
1
INTRODUCTION
1.4
BACKGROUND
OF STUDY
African yam bean (Sphenostylis stenocarpa Hochst ex A.
Rich) is a herbaceous leguminous plant occurring throughout tropical Africa
(Porter, 1992). It is often cited among the lesser-known species (Amoatey et al., 2000). It is grown as a minor
crop in association with yam and cassava. African yam bean serves as security
crop; it has the potential to meet year round protein requirements if grown on
a large scale (World Health Organization (WHO), 2002). African yam bean (AYB)
is highly nutritional with high protein, mineral and fiber content, its protein
content is reported to be similar to cowpea, soybean and pigeon pea (Obizoba
and Souzey, 1989; Ene-Obong and Carnovale, 1992; Uguru and Madukaife, 2001) It
has high metabolic energy, low true protein digestibility (62.9 %), moderate
mineral content, the amino and fatty acids contents are comparable to those of
most edible pulses (Nwokolo, 1987; Uguru and Madukaife, 2001). It has a high
water absorption capacity when compared with cowpea (Achinewhu and Akah, 2003).
Induced mutagenesis in plants dates back to the beginning of the
20th century. Physical mutagenic treatments have included gamma, X-ray and
neutron irradiation. In the 1950s there was a global spread of gamma
irradiators for plant mutagenesis, especially to create desired mutants for
plant breeding. Protocols for gamma irradiation were optimised and many mutant
plant varieties have been released. However, gamma sources (usually the
radioactive isotopes: Cobalt-60 and Cesium-137) have become security risks and
strict international regulations are imposed on the shipment of gamma sources,
the production of gamma sources and the refurbishment of old gamma irradiators
(Mastrangelo et al., 2010). These
restrictions now limit gamma irradiation for plant mutagenesis. The Plant
Breeding and Genetics Laboratory (PBGL) of the FAO/IAEA have therefore embarked
on a series of investigations aimed at optimizing X-rays for plant mutagenesis.
Our initial studies have focused on developing procedures and adapting an
existing commercially available X-ray machine that has been used extensively in
the FAO/IAEA Insect Pest Control Laboratory to produce sterile male insects for
SIT (Parker and Mehta, 2007.
1.2
JUSTIFICATION
X-rays
are a form of electromagnetic radiation, just like light waves and radio waves.
Because X-rays have higher energy than light waves, they can pass through the
body. X-rays were first discovered over 100 years ago and were quickly applied
to medical diagnostic use (Song et al.,
2006). Today x-rays remain a valuable tool in diagnosis and treatment of many
injuries and diseases and effects of radiation on plants are a broad and
complex field and work is being done in many areas on a large number of plant
species. Radiation affects the size and weight of plants and has influences on
plant root growth (Flavel et al.,
2012).
Induced
mutagenesis through x-ray irradiation has been identified as one of the
approaches to be adopted to create variability in this crop. Induced mutation
has led to remarkable advances in crop improvement. Plant characters such as
height, disease resistance, yields and nutritional qualities have been obtained
through induction by mutagenic agents such as X – ray and gamma – ray (Iwo et
al., 2013). It offers the possibility of inducing desired attributes that
either cannot be expressed in nature or have been lost during evolution.
Induced mutation either by physical or chemical mutagen is practical approach
useful in varietal development of vegetative propagated plants (Simmond, 1979).
However, there have not been many reports on the effects of x-ray radiation on
the growth of African yam bean.
Exposure
of mungbean and cowpea seeds treated with x-rays show significant increase in
all growth parameters such as plant length and weight, leaf area and number of
nodules. Similarly, Dewar et al., 2010
observed that soil drenching with T. harzianum, R. meliloti and P.
aeruginosa and seeds of sunflower, mung bean were exposed with gamma rays
at 0, 2, 8 and 16 minutes interval, completely reduced the infection of R.
solani, M. phaseolina and Fusarium spp. Thapa, 2010 also reported
that root, hypocotyl, and epicotyl elongation decreases as the exposure
time of the x-ray increases. Present results supported
by Thapa that germination and seedling growth of Pinus kesiya and Pinus
wallichiana were inhibited with the increased in exposure of gamma rays
whereas in some cases the lower exposure was stimulatory. Irradiation of mungbean seeds with gamma rays
for 0 and 4 minutes enhance the growth parameters in terms of shoot length,
shoot weight, root length, root weight, leaf area and reduce the infection of
root infecting fungi (Ikram et al.,
2010).
In
view of the above facts, the present study was undertaken to study the effects
of x-ray doses on the growth parameters of Sphenostylis
stenocarpa.
1.3
AIM AND OBJECTIVES
The aims and objectives of this
research work are as:
- To
establish the dosimetry of X-ray on two African yam bean accessions.
- To
investigate the effects of different doses of Xs-rays on growth parameters
such as plant height, number of leaves, number of branches, leaf area,
root length, germination percentage and stem girth.
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