ABSTRACT
This work studied the biofertilizer potentials of Rhizobium leguminosarum and Pseudomonas aeruginosa on two common tropical vegetables plant Talinum triangulare (waterleaf) and Telfairia occidentalis (pumpkin). The test microorganisms were isolated from agricultural soils, characterised and identified. Each test organism was inoculated into carrier base material (activated charcoals) at three concentrations of 2.50×108 cells/kg, 5.0×108 cells/kg, and 7.5×108 cells/kg for each test vegetable. Controls of uninoculated sterile activated charcoal were set up for each vegetable as well as N.P.K fertilizer applied at rates of Treatment1 (2.50×108 cells/kg dose of the microbes with the carrier base material), Treatment2 (5.0×108 cells/kg dose of the microbes with the carrier base material), and Treatment3 (7.5×108 cells/kg dose of the microbes with the carrier base material) for each vegetable. Three growth performance indices considered for the evaluation of the biofertilizer potentials were plant biomass, plant height and mean leaf area measured after 28 days of cultivation. Result obtained show that there were significant variations in the impact of the test biofertilizer on the both vegetables. Pseudomonas aeruginosa increased the biomass of the vegetables by 100.54% to 142.87% in waterleaf and by 167.75% to 368.10% in pumpkin while Rhizobium leguminosarum caused increases of 107.77% to 286.78% (waterleaf) and 166.52% to 358.26% (Ugu). These were on the average, higher than the measures obtained with N.P.K fertilizer which ranged from 12.78% to 206.69% (waterleaf) and 52.07% to 376.13% (Ugu). Similarly increases were recorded in the mean leaf areas of the vegetables. In the P.aeruginosa innoculated waterleaf, the increase was from 73.03% to 221.16% and for Ugu, it was 92.34% to 208.06%. The corresponding increases in the Rhizobium innoculated vegetables were 172.17% to207.01% (waterleaf) and 23.29% to 164.27% (Ugu). This also varied from the values recorded from the chemically fertilized vegetables; 8.90% to 222.16% (waterleaf) and 48.27% to 187.57% (Ugu). Conversely, much lower impacts were recorded in the plant height of the biofertilized vegetables with values of 4.04% to 30.58% and Pseudomonas and Rhizobium innoculated waterleaf and Ugu recorded increase with the value of 0% to 20.06% respectively. The values for Rhizobium innoculated plants were 36.35% to55.05% (waterleaf) and 13.77% to 36.42% whereas the chemically fertilized vegetables recorded height increases of 0% to 8.09% in waterleaf and 23.33% to 168.53% in Ugu. It was concluded, on the basis of findings recorded in this work, that the two test bacteria (Pseudomonas aeruginosa and Rhizobium leguminosarum), have great potentials for utilization as fertilizers. Since the success of this research work has been established, there is need for tests on these and possibly other organisms on other vegetable types as well as a determination of optimal environment with respect to field validation of this success recorded at in house trials. This is recommended for future works and for trail field validation of this important research finding.
TABLE OF CONTENTS
Title
Page i
Declaration
ii
Certification iii
Dedication iv
Acknowledgements
v
Table
of Contents vi
List
of Tables ix
List
of Figures x
Abstract xi
CHAPTER 1:
INTRODUCTION 1
1.1 Background
of Study 1
1.2 Statement
of Problem 3
1.3 Justification
of this Research 4
1.4 Aims of
the Study 4
1.5 Objectives of the Study
4
CHAPTER 2:
LITERATURE REVIEW 6
2.1 Definition
of Biofertilizers 6
2.2 Nitrogen-Fixing
Bacteria as Microbial Biofertilizers 8
2.3 Symbiotic
Nitrogen-Fixing Bacteria 10
2.3.1 Rhizobia 10
2.3.2 Frankia 12
2.3.3 Cyanobacteria 13
2.3.4 Nitrogen-fixing associated bacteria 13
2.3.5 Free-living nitrogen-fixing bacteria 15
2.3.6 Plant-growth-promoting rhizobacteria 16
2.3.7 Phosphorus-solubilizing bacteria 16
2.3.8 Plant hormone production by bacteria 17
2.4 Types
of Biofertilizers 18
2.4.1 Nitrogen
biofertilizers 18
2.4.2 Phosphorus
biofertilizers 22
2.4.3 Compost
biofertilizer 24
2.4.4 Liquid
biofertilizers 24
2.5 Equipment
Required for Biofertilizers Production 28
2.6 Mass
Production of Biofertilizers 30
2.7
Application of Biofertilizers 36
2.8 The Advantages
of Biofertilizers Over Chemical Fertilizers
40
2.9 Economic
Importance of Biofertilizers 41
2.9.1 Constraints
in biofertilizers technologies 42
2.9.2 Availability
and cost efficient of biofertilizers 45
2.9.3 Talinum triangulare 46
2.9.4 Telfairia
occidentalis 48
CHAPTER 3:
MATERIALS AND METHODS 53
3.1 Source
of Material 53
3.2 Experimentation
Design 53
3.3 Isolation
of Bacterial Biofertilizer 55
3.3.1 Isolation
of Rhizobium leguminosarum 56
3.3.2 Isolation
of Pseudomonas aeruginosa 57
3.3.3 Preparation
of biofertilizers inoculum 57
3.4 Identification
of Test Organisms 58
3.4.1 Colony
morphology 58
3.4.2 Microscopic
characteristics 58
3.4.3 Biochemical
reaction tests 58
3.4.4 Carbohydrates
(sugar) utilization test 59
3.4.5 Identification
of isolates 59
3.4.6 Molecular
identification of isolates 59
3.4.7 Application
of the biofertilizers to the plant 60
3.5 Tests for Biofertilizers Potential of Rhizobium leguminosarum and Pseudomonas aeruginosa 60
3.5.1 Determination
of plant height 61
3.5.2 Determination
of plant biomass 61
3.5.3 Determination
of plant leaf area 62
3.6 Assessment
of the Effects of Biofertilizers on Test Plants 63
3.6.1 Effects
of biofertilizer application on the plant biomass 63
3.6.2 Effect
of biofertilizer on the plant height 63
3.6.3 Effect
of biofertilizer on the plant area 64
3.7 Statistical Comparisons 64
CHAPTER 4: RESULTS AND DISCUSSION
65
4.1 Results 65
4.2 The Biomass of the Vegetables Grown with
Microbial Biofertilizer
and the Controls. 65
4.3 Vegetative Growth (Plant Height) of
Vegetables Grown with
Biofertilizers and the Controls. 68
4.4 Leaf area Measurement of the Vegetables
Grown with Biofertilizers and
their Controls. 70
4.5 Effect of Biofertilizers, Pseudomonas aeruginosa and Rhizobium leguminosarum, on the Biomass of the Two Test Vegetables Telfairia occidentalis and Talinum triangulare. 73
4.6 Effect of the Biofertilizer on the Plant
Height of the Test Vegetables
Telfaira occidentalis and Talinum triangulare. 75
4.7 Discussion
79
CHAPTER 5:
SUMMARY, CONCLUSION AND RECOMMENDATION 81
5.1 Summary 81
5.2 Conclusion 82
5.3 Recommendation 83 References
Appendix
LIST OF TABLES
2.1: The different ways biofertilizers are
grouped, based on their nature and
function 9
2.2: The
seed treatment application method 38
3.1: Shows
the experimental design layout representing the block design 54
4.1: Mean
biomass of vegetables grown with biofertilizer 67
4.2: Plant
height of vegetables grown with biofertilizers (cm) 69
4.3: Leaf
areas of vegetable grown with biofertilizers and control (cm2) 72
4.4: Effect
of biofertilizers on biomass of vegetables 74
4.5: Effect
of biofertilizers on the plant height of vegetables 76
4.6: Effect
of biofertilizers on the leaf area of the grown 78
LIST
OF FIGURES
2.1 Schematic
representation of mass production of bacterial biofertilizers 35
2.2 Mass
production of mycorrhizal biofertilizer 35
2.3 Talinum triangulare (waterleaf) 48
2.4 Telfaria occidentalis (pumpkin) 52
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Agriculture is known as the most important economic sector in
all developing countries. Particularly, 45-60% of the labour force in Nigeria
is engaged in agricultural activities and agriculture contributes up to 30-40%
of the gross national product (The World bank, 2008). Vegetables are used as food and as raw materials for
industries, which also serves for economic interest. One
of the major concerns in today's world is the pollution and contamination of
soil. The use of chemical fertilizers and pesticides has caused tremendous harm
to the environment. An answer to this is the bio-fertilizer, an environmentally
friendly fertilizer now used in most countries. Bio-fertilizers are organisms
that enrich the nutrient quality of soil. The main sources of bio-fertilizers
are bacteria, fungi, and cyanobacteria (blue-green algae). The
most striking relationship that these have with plants is symbiosis, in
which the partners derive benefits from each other (Youssef et al., 2014). Bio-fertilizer is a
substance which contains living microorganisms which, when applied to the seed,
plant surfaces or soil colonizes the rhizosphere or the interior of the plant
and promotes growth by increasing the supply or availability of primary
nutrients to the host plant. Bio-fertilizers add nutrients through the natural
processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant
growth through the synthesis of growth-promoting substances. Bio-fertilizers
can be expected to reduce the use of chemical fertilizers and pesticides. Bio-fertilizers
provide eco-friendly organic agro-input and are more cost-effective than chemical
fertilizers. Since a bio-fertilizer is technically living, it can symbiotically
associate with plant roots. Involved microorganisms could readily and safely
convert complex organic material in simple compounds, so that plants are easily
taken up. It maintains the natural habitat of the soil. It increases crop yield
by 20-30%, replaces chemical nitrogen and phosphorus by 25% and stimulates
plant growth. It can also provide protection against drought and some soil borne
diseases. Very often
microorganisms are not as efficient in natural surroundings as one would expect
them to be and therefore artificially multiplied cultures of efficient selected
microorganisms play a vital role in accelerating the microbial processes in
soil. Use of biofertilizers is one of the important components of integrated
nutrient management, as they are cost effective and renewable source of plant
nutrients to supplement the chemical fertilizers for sustainable agriculture.
Several microorganisms and their association with crop plants are being
exploited in the production of biofertilizers (Hayat et al,.2010). Generally, the use of microorganisms as biofertilizer
has wide application in terms of crops covering legumes, cereals, roof and
tuber crops (Mohammed et al., 2009,
Paudey, 2006).
The
use of microbial biofertilizer has been described as an important component of
integrated nutrient management which is not only cost effective but represents
a renewable nutrient source which supplements the use of chemical fertilizers.
Essentially, biofertilizers help plant to take up nutrients through microbial
activities at the rhizosphere which include interactions which accelerate
microbial processes in the soil to augment the extent of nutrients availability
in easily assimilated form to plants.
Presently,
there is growing interest in the use of microorganisms as biofertilizer owing
to the relative advantages over chemical fertilizers. Biofertilizers restore
soil’s natural nutrient cycle and build up organic matter thus representing an
eco-friendly organic agricultural input. They generally promote plant growth
and at the same time enhance sustainability and health of soil. It has been
observed, that some important plant nutrient like phosphate is rarely available
in quantity that meet plants need and this is attributed to phosphate
immobilization by some mineral element like iron, aluminum, calcium, etc (Pandey,
2006). Findings also show that less than 20% of added phosphate as chemical
fertilizer, is absorbed by plants for the same reasons while the rest is either
immobilized or leached out and therefore unavailable to plant thereby resulting
in wastage and ecological pollutions. Mohammed et al. (2009) cited the above as one of the factors which make it
imperative to resort to the use of phosphate solubulizing microorganisms as
biofertilizer in perference to chemical phosphate fertilizers.
Some
scholars (Sullivan, 2001) have described biofertilizers as microbial inoculants
which represent agricultural soil amendment that uses beneficial microorganisms
to promote plant health as the microbes form symbiotic relationship with the
target crop and both benefit mutually. Besides phosphate solubulization and
immobilization, biofertilizer organisms improve the soil by increasing the
availability of other primary nutrients. The Azotobacter and Rhizobium
species fix nitrogen in the soil. While Rhizobium
is seen by many as the most efficient biofertilizer due to its symbiotic
fixation of atmospheric nitrogen, the Azotobacters
are known to in addition, improve soil aggregation by their ability to produce
slime.
In
view of the successes recorded here with microbial biofertilizers, and in
consideration of their numerous agricultural advantages, this project is
designed to evaluate the use of some bacterial species as biofertilizer and
their impact on growth pattern of two common vegetable plants Talinum trangulare,and Telferia occidentalis.
1.2 STATEMENT OF PROBLEM
Crop
production needs to be increased substantially to reduce hunger and food
insecurity in West Africa. Since most soils in the region are inherently poor,
external inputs are necessary to boost crop production. In addition, there is a
need to improve crop productivity in an eco-friendly manner and this has led to
the promotion of commercial biological products called biofertilizer intended
to restore or enhance the fertility and organic matter content of soils.
1.3 JUSTIFICATION OF THIS RESEARCH
With
the ongoing adverse effects of using Chemical fertilizers to both the plants,
human and animal life, it has become imperative to seek an alternative to this
menace and the urgent need of providing an eco-friendly alternative to chemical
fertilizers, An answer to this is biofertilizer, an environmentally friendly
fertilizer now used in most countries. Soil microorganisms play significant role
in organic matter decomposition and release of plant nutrients such as nitrogen
(N), phosphorus (P) and sulfur (S). Therefore, microorganisms are important
component of integrated nutrient management systems and soil biodiversity.
Biofertilizer has gained advantage over chemical fertilizers and its usage is
cheaper and better. Therefore, a success
in this work will help solve and bridge the gap caused by chemical fertilizer
and make biofertilizers readily cheap and available for farmers.
1.4 AIMS OF THE STUDY
The
aim of the project work is to evaluate the use of some soil bacteria (Rhizobium leguminosarum and Pseudomonas aeruginosa) as biofertilizer
and their impact on growth performance of two common vegetable plants, Talinium triangulare and Telferia occidentalis.
1.5 OBJECTIVES OF THE STUDY
I.
To isolate and identify
of Rhizobium and Pseudomonas species.
II.
To do molecular
characterization of the isolates
III.
To test the biofertilizer
potential of the two isolates using the two plant seedlings.
IV.
To assess the growth
performances of the two biofertilized vegetables based on plant
height,
biomass, and leaf area; after a growth period of eight weeks, relative to that
of controls (Non biofertilizer plants).
V.
To statistically compare
the growth performance of the biofertilized plants relative to the controls, as
well as between the test organisms.
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