ABSTRACT
Yam is one of the most important dietary sources of energy
for households in West-Africa. Yam stores relatively longer than most root
crops and this attribute have gained it recognition as a food security crop in
Ghana. More effort has been put into its research and production as has been
seen by numerous government interventions over the years. However, inadequate
access and high cost of seed yams have prevented farmers from intensive
sustainable production. New technologies to increase and make available quality
seed yams to farmers can boost yam production, increase food security and
improve farmers’ livelihoods. In this regard, two aeroponic systems were
developed and evaluated. The two systems; power-dependent (pressurised) and
power-independent (gravity-fed) were evaluated using a split-split plot design
at the CSIR-Crops Research Institute. The evaluations were carried out to
assess the technical and agronomic performance of the systems. The aeroponic
units were the main plots, the nutrient concentrations the sub-plot, and the
yam varieties the sub-sub plot. Data collected on performance of the various
treatments were subjected to analysis of variance and judged significant at
p < 0.05. Technical evaluation of the two aeroponic systems gave Christensen’s
Coefficient for water distribution uniformity values were 97.52 % and 94.49 %
for the power-dependent and power-independent systems respectively. Agronomic
performance showed significant differences in number of mini-tubers harvested
and weight of mini-tubers under the different aeroponic systems. Field
evaluation of harvested mini-tubers also showed significant differences in
final yields under the various nutrient concentrations. Economic analysis of
the two systems showed a benefit-cost ratio in favour of the power-independent
system. Various recommendations were made after a repeat of the experiment. The
power-independent system would be disseminated to smallholder farmers for seed
propagation.
CHAPTER ONE
INTRODUCTION
1.1 General Introduction
Yams (Dioscorea spp.) are among the most important staple
foods in the world, especially in some parts of the tropics and subtropics
(Okigbo and Ogbonnaya, 2006). It belongs to the family Dioscoreaceae (genus
Dioscorea). Yams are native to tropical regions throughout the world. They are
cultivated for their edible tubers, which in some species can grow up to about
2.4 m long and weigh up to 45 kg (Okigbo and Ogbonnaya, 2006). Yam is largely
carbohydrate and is one of the cheaper sources of the nutrient to humans
(Kochlar, 1981). Yams are major sources of nutrients (carbohydrates, phosphorus
calcium) and vitamins such, iron and vitamins such as thiamine, riboflavin, and
vitamins B and C (Coursey, 1967).
Yam is one of the most important dietary sources of energy
produced within the tropics and plays a major role as a food and trade
commodity in West-Africa. It stores relatively longer than most root crops
(e.g. cassava), availing itself on the market for a considerable part of the
year. This attribute has gained it recognition as a food security crop in
Ghana. In Ghana, yam is produced mostly in the Guinea-Savannah and
Forest-Savannah transition zones with commercial yam production areas such as
Mampong, Ejura, Kintampo, Atebubu, Wenchi, Kete-Krachi, Yendi, Bole, Tamale and
Wa (Twumasi, 1986). However, reasonable production occurs in almost all
regions. About 80% of yam produced in Ghana is white yam, which is much
preferred among the yam varieties (Tetteh and Saakwa, 1991).
Ghana is a major yam exporter in the world, exporting 20,841t
in 2008 (MiDA, 2009). There are a lot of challenges with yam production in
Ghana, chief among them being unavailability and high cost of seed yams.
Growing yams in Ghana is labour intensive and land demanding because of its
over reliance on traditional production techniques. Furthermore, farmers rely
on traditional method of milking for seed generation. As a vegetatively
propagated crop, all parts of the yam, with a bit of the tuber skin attached
(known as setts) is expected to germinate even though most farmers prefer using
the yam “head”. The size of ware yam harvested usually depends on the size of
sett used in its cultivation. Farmers therefore prefer using whole setts,
however big or small for planting. To generate such whole setts, farmers use a
technique known as “milking”. This process involves early harvesting of ware
yams to pave way for a second tuber that can be used as seed only in early
maturing varieties. After “milking”, if the second tuber regrowth is not met
with favourable weather conditions, the farmers cannot get enough seed to use
in the next season’s planting, thus having to leave a substantial part of the
ware yam as seed for planting.
1.2 Problem Statement
Yam is an intensively cultivated root/tuber crop in Africa,
only following cassava in terms of production volumes (Mignouna et al., 1998)
with mean yields of about 10 t/ha. It is a food security crop in most of
sub-Saharan Africa (Delebo, 2008). In 2007, yam production worldwide was almost
52 million tonnes with 96 % of this coming from Africa (IITA, 2006). There is a
high labour requirement in yam production. Challenges also persist in the
availability of high quality yam seeds, mechanization and staking especially in
the forest areas, weed control and harvesting, which account for over 40 % of
the total yam production cost (Nweke et al. In: Okoro, 2008).
Yams are predominantly grown by small scale farmers in Ghana.
Most of these farmers propagate their seed yams using traditional methods such
as “milking” or harvesting the ware yams early and the use of “yam heads” or
parts of the yam that can easily sprout. The setback with these methods is that
they do not produce enough and/or good quality seed yams (MiDA, 2008). Also, if
the second plant propagation (after “milking”) is not met with favourable
weather conditions, farmers could lose most or all of their seed yams and end
up with nothing to plant the next season. This can result in the farmer
spending more money than initially intended, in the acquisition of seed yams
for the next season’s planting. This arrangement is even subjected to the
availability and affordability of seed yams on the market, which is not the
case in most cases.
1.3 Project Justification
Research has produced methods that results in a higher
propagation ratios for yams. These include the minisett technology with a
multiplication ratio of 1:30, in-vitro tissue culture multiplication with a
ratio of 1:200 and in-vivo yam vine multiplication with a ratio of 1:240 (CSIR-CRI,
2012) which has not been fully disseminated. Unfortunately, adoption of these
technologies is low, and to a high degree, not attained the needed impact
despite its numerous advantages.
The minisett technology developed and promoted by
International Institute for Tropical Agriculture (IITA, 2006) and CSIR-Crops
Research Institute (CSIR-CRI, 1991) in Ghana is still striving to attain high
adoption by farmers. Minisett is based on a principle targeted at increasing
the number of setts derived from one tuber. In this technique, one tuber can be
sliced, with tuber skin attached, into about 40 pieces ranging in weight from
50-100 g each. The cut pieces are dipped in a solution containing pesticides to
disinfect the setts before planting (MiDA, 2010).
Despite the high propagation rate and low disease infestation
of the minisett technology, many farmers still rely on the age old method of
using tubers of ware yam or milked yam for planting.
Plants require light, water, nutrients, oxygen and carbon
dioxide for photosynthesis. Soil can be a supplier of nutrients, but is not
necessary in and of itself - hence the effectiveness of hydroponic and
aeroponics. Water is also becoming more and more scarce as a commodity and as
global population increases, the concern over water and soil quality also
continues to grow.
New technologies for growing foods that are not overly
dependent on soils and water are becoming not only a distinct advantage, but a
necessity. The aeroponics and hydroponics technologies have been demonstrated
in several ways to be a significantly more water- and energy-efficient means
for food production. Hence, the hydroponics and aeroponics technology is being
adapted for use in this research to propagate seed yam.
In aeroponics, plants are grown in an air or mist environment
without engaging soils or any soil aggregate or soil medium (Arunkumar and
Manikand, 2011). Aeroponics gives room for easy access to plant roots since it
is not planted in any aggregate media (Pagliarulo and Hayden, 2002). The growth
chamber and fertigation system employed in aeroponics also give room for
complete regulation of the root zone setting, including temperature, humidity,
pH, nutrient concentration, mist application frequency and duration. Plants grown
using aeroponics often show signs of accelerated growth and early maturity
(Mirza et al., 1998). These abilities have made the technology a popular
research tool for studying root growth and nutrient uptake (Barak et al.,
1998). Aeroponically generated seed yams can improve the seed multiplication
ratio of yams and thus make available more seed yams on the market. It can also
reduce disease incidence of seed yams which results in yield losses.
Aeroponics, if successfully used in the propagation of seed
yams, can significantly increase the incomes of farmers, improve access to
quality seed yams all year round (by making it more accessible and affordable
to commercial growers and small scale farmers) and reduce the production costs
of yams. This would improve farmers’ livelihood and also enhance food security
in the country.
1.4 Objectives of the Study
The overall objective of this research was to determine the
feasibility of generating seed yams from aeroponic systems.
1.4.1 Specific Objectives
To achieve the main objective of this work, the following
sub-objectives were developed:
Design, set up and test two types of aeroponic systems
(power-dependent and power-independent) for propagating seed yams
Evaluate the two aeroponic systems for their ability to
agronomically propagate mini-tubers successfully
Assess the ability of the resulting mini-tubers to be used
for propagating seed yams and
Determine the economics of using either of the two aeroponic
systems to commercially produce seed yams.
1.5 Research Questions
The following questions were formulated to guide the study:
Are there differences in the fabrication and operation of the
two designed aeroponic systems?
Are there differences in growth and yield of seed yams from
the two aeroponic designs?
Can the mini-tubers generated from either of the systems be
used to propagate seed yams?
What are the cost implications of using either of the two
systems to propagate seed yams?
1.6 Research Hypotheses
The following research hypothesis guided the studies:
The alternative and null hypothesis for objective one
The Null hypothesis (HO): System performance of the
power-dependent set up is same as the power-independent set-up.
The alternate hypothesis (HA): System performance of the
power-dependent set up is not the same as power-independent set-up.
The alternative and null hypothesis for objective two
The null hypothesis (HO): Agronomic performance of vine
cuttings grown using the power-dependent system is same as that of the
power-independent system
The alternate hypothesis (HA): Agronomic performance of vine
cuttings grown using the power-dependent system is not the same as that of the
power-independent system
The null and alternative hypothesis for objective three
The null hypothesis (HO): Agronomic performances of resulting
mini-tubers from both the power-dependent and power-independent aeroponic
systems are same
The alternative hypothesis (HA): Agronomic performances of
the resulting mini-tubers from the power-dependent and power-independent
systems are not the same.
The null and alternative hypothesis for objective four
The null hypothesis (HO): There are no economic differences
in the design, fabrication and operation of the two aeroponic systems.
The alternative hypothesis (HA): There are economic
differences in the design, fabrication and operation of the two aeroponic
systems.
1.7 Limitations of the Research
The following are the limitations of this research:
The initial set-up of the two aeroponic systems was capital
intensive.
One of the systems evaluated was power-dependent and
vulnerable to power outages (a more common event in Ghana as it faces an energy
crisis). Prolonged power interruptions could have led to irreversible damages
to the plants, thus additional costs were incurred in providing for a standby
generator.
The aeroponic technology involves a lot of expertise and also
requires constant attention and maintenance.
1.8 Organization of the Research
This thesis is organised into six (6) chapters. The first
chapter constitutes the general introduction to the research, detailing the
background, justification, objectives, research questions and hypothesis and
the limitations of the study.
Chapter Two reviews literature on yams and its production in
Ghana defines and explains aeroponics, its advantages and uses in research as
well as its limitations. Also a general overview is given on the types of
aeroponic systems based on their components, accessories and operation.
Chapter Three details the designs, fabrication and setting up
of the two aeroponic systems and also reports on the materials and methods used
in the technical evaluation of the two aeroponic systems as well as results
from the evaluation. It gives detailed description of the aeroponic designs,
its setting up and operational characteristics as well as the experimental
designs used in their evaluation.
Chapter Four reports on the materials and methods used in the
agronomic evaluation of vines planted on the aeroponic systems as well as
evaluation of the resulting mini-tubers from the aeroponic propagation. The
methods explain the type of research designs adopted for the agronomic
evaluations of the systems. It also includes various data collection methods
and analysis.
Chapter Five presents the data, calculations/derivations and
results of analysis from the various agronomic experiments. It further
interprets and discusses results obtained from the study.
Chapter Six presents a summary of the major outcomes of the
research, the conclusion made from the analysis and proposes areas for further
research as well as recommendations for policy makers.
For more Agricultural Engineering Projects Click here
===================================================================
Item Type: Ghanaian Topic | Size: 229 pages | Chapters: 1-5
Format: MS Word | Delivery: Within 30Mins.
===================================================================
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.