ABSTRACT
The effect of introducing garden egg (Solanum aethiopicum)
to fluted pumpkin (Telfairia occidentalis) in a relay intercrop on the growth
of crop mixture under rainfed conditions (September to November, 2014) was
investigated at the Faculty of Agriculture University of Benin, Benin City
Nigeria.
Garden egg and a local variety of fluted pumpkin were sown
sole and intercrop. Garden egg and fluted pumpkin were planted sole and
intercropped to evaluate their interaction effect on growth parameters such as
plant height, stem girth, leaf number, and leaf area. Data obtained were
subjected to analysis of variance (ANOVA).
The study reveals that intercropping of garden egg with
fluted pumpkin significantly increased the growth of garden egg, as
intercropped garden egg had significant increase as against sole garden egg.
The same was not found to be true for fluted pumpkin as sole fluted pumpkin had
significant growth increase but when intercropped, there was significant
reduction in growth.
CHAPTER ONE
1.0 INTRODUCTION
Self-sustaining, low-input, and energy-efficient
agricultural systems in the context of sustainable agriculture have always been
in the centre of attention of many farmers, researchers, and policy makers
worldwide (Altieri et al., 1983; Altieri, 1999). However, most practices of
modern agriculture, e.g. mechanization, monocultures, improved crop varieties,
and heavy use of agrochemicals for fertilization and pest management, led to a
simplification of the components of agricultural systems and to a loss of
biodiversity. Restoring on-farm biodiversity through diversified farming
systems that mimic nature is considered to be a key strategy for sustainable
agriculture (Jackson et al., 2007; Scherr and McNeely, 2008). On-farm
biodiversity, if correctly assembled in time and space, can lead to
agroecosystems capable of maintaining their own soil fertility, regulating
natural protection against pests, and sustaining productivity (Thrupp, 2002;
Scherr and McNeely, 2008). Biodiversity in agroecosystems can be enhanced in
time through crop rotations and sequences in space through cover crops,
intercropping, and agroforestry (Altieri, 1999; Malézieux et al., 2009). While
modern agriculture has brought vast increases in productivity to the world’s
farming systems, it is widely recognized that much of this may have come at the
price of sustainability (Tilman et al., 2002; Lichtfouse et al., 2009). This is
because modern farming systems imply the simplification of the structure of the
environment over vast areas, replacing natural plant diversity with only a
limited number of cultivated plants in extensive areas of arable monocultures
(Vandermeer et al., 1998). By contrast, on farm biodiversity is familiar to
traditional farmers mainly in developing countries, where traditional farming
systems are characterized by their great degree of genetic diversity in the
form of mixed cropping and agroforestry patterns, based on numerous varieties
of domesticated crop species as well as their wild relatives (Altieri, 1999).
These farming systems offer a means of promoting diversity of diet and income,
stability of production, reduced insect and disease incidence, efficient use of
labor, intensification of production with limited resources, and also
maximization of returns under low levels of technology (Anil et al., 1998;
Malézieux et al., 2009). Intercropping, also referred to as mixed cropping or
polyculture, is the agricultural practice of cultivating two or more crops in
the same space at the same time (Andrews and Kassam, 1976; Ofori and Stern,
1987; Anil et al., 1998). The component crops of an intercropping system do not
necessarily have to be sown at the same time nor they have to be harvested at
the same time, but they should be grown simultaneously for a great part of their
growth periods. In intercropping, there is normally one main crop and one or
more added crop(s), with the main crop being of primary importance for economic
or food production reasons. The two or more crops in an intercrop normally are
from different species and different plant families, or less commonly they may
be simply different varieties or cultivars of the same crop, such as mixing two
or more kinds of wheat seed in the same field. The most common advantage of
intercropping is to produce a greater yield on a given piece of land by
achieving more efficient use of the available growth resources that would
otherwise not be utilized by each single crop grown alone. There are many
different kinds of species that can be used for intercropping such as annuals,
e.g. cereals and legumes, perennials, including shrubs and trees, or a mixture
of the two (annuals and perennials). In the case of shrubs and trees the term
mostly used is agroforestry. The objective of this paper is to provide an
overall view and evaluation of annual intercropping, summarizing its main
advantages supported by a number of key examples from the published literature
which point out its great value in the context of sustainable agriculture. This
paper focuses on relay intercropping and not on agroforestry using garden egg
and fluted pumpkin intercrop as case study.
The objective of this study is to evaluate the influence of
intercropped telfairia and its time of intercropping on the growth yield of
garden egg.
Meaning of Intercropping
Intercropping is the practice of growing two or more crops
in close proximity and it is practiced by majority of farmers in the tropical
and subtropical regions of the world. The system is widely practiced because it
suppresses weeds and reduces pest disease infestation. (Ibeawuchi, 2007).
The degree of spatial and temporal overlap in the crop or
more crops can be varied. As a result, numerous types of intercropping in which
the temporal and spatial mixture have been varied to some degree have been
identified (Andrews and Kassam, 1975).
Types of intercropping (spatial and temporal patterns)
Several types of intercropping, all of which vary the
temporal and spatial mixture to some degree, have been described (Andrews and
Kassam, 1976). The degree of spatial and temporal overlap in the component
crops can vary somewhat, but both requirements must be met for a cropping
system to be an intercrop. Thus, there are several different modes of component
crops (Willey, 1985). Yield advantage occurs because growth resources such as
light, water, and nutrients are more completely absorbed and converted to crop
biomass by the intercrop over time and space as a result of differences in
competitive ability for growth resources between the component crops, which
exploit the variation of the mixed crops in characteristics such as rates of
canopy development, final canopy size (width and height), photosynthetic
adaptation of canopies to irradiance conditions, and rooting depth (Midmore,
1993; Morris and Garrity, 1993; Tsubo et al., 2001). Regularly intercropped
pigeon pea or cowpea can help to maintain maize yield to some extent when maize
is grown without mineral fertilizer on sandy soils in sub-humid zones of
Zimbabwe (Waddington et al., 2007). Intercropping maize with cowpea has been
reported to increase light interception in the intercrops, reduce water
evaporation, and improve conservation of the soil moisture compared with maize
alone (Ghanbari et al., 2010). This yield advantage occurs when the component
crops do not compete for the same ecological niches and the interspecific
competition for a given resource is weaker than the intraspecific competition.
Normally, complementary use of resources occurs when the component species of
an intercrop use qualitatively different resources or they use the same
resources at different places or at different times (Tofinga et al., 1993). In
ecological terms, resource complementarity minimizes the niche overlap and the
competition between crop species, and permits crops to capture a greater range
and quantity of resources than the sole crops. Improved resource use gives in
most cases a significant yield advantage, increases the uptake of other
nutrients such as P, K, and micronutrients, and provides better rooting ability
and better ground cover as well as higher water use efficiency (Midmore, 1993;
Morris and Garrity, 1993). Thus, selection of crops that differ in competitive
ability in time or space is essential for an efficient intercropping system as
well as decisions on when to plant, at what density, and in what arrangement.
Although in this way cropping management decisions specify the design of
intercropping systems, intercrop performance is governed largely by the
availability of and the competition for the environmental resources. Research
has shown that intercrops are most productive when component crops differ
greatly in growth duration (Wien and Smithson, 1981; Smith and Francis, 1986;
Fukai and Trenbath, 1993; Keating and Carberry, 1993). For example, when a long
duration pigeon pea cultivar was grown in mixture with three cereal crops of
different growth durations, i.e. setaria, pearl millet, and sorghum, the Land
Equivalent Ratio was highest with the quick-maturing setaria and lowest with
the slow-maturing sorghum (Rao and Willey, 1980). It must be noted here that
Land Equivalent Ratio shows the efficiency of intercropping for using the
environmental resources compared with monocropping with the value of unity to
be the critical value. When the Land Equivalent Ratio is greater than one
(unity) the intercropping favours the growth and yield of the species, whereas
when the Land Equivalent Ratio is lower than one the intercropping negatively
affects the growth and yield of the plants grown in mixtures (Willey, 1979;
Willey and Rao, 1980). Asynchrony in resource demand ensures that the late
maturing crop can recover from possible damage caused by a quick-maturing crop
component and the available resources, e.g. radiation capture over time, are
used thoroughly until the end of the growing season (Keating and Carberry,
1993). By contrast, when the component crops have similar growth durations
their peak requirements for growth resources normally occur about the same time
and the competition for the limiting growth resources is intense (Fukai and
Trenbath, 1993).
In intercropping crops could be arranged in any of the
following forms.
Mixed cropping – Here component crops are totally, mixed in
the available space without any form of arrangement.
Row cropping– The component crops are arranged in alternate
rows. A variation of row cropping includes multiple rows of another.
Relay cropping– Here the second crop is sown at the onset of
reproductive development or fruiting of the first crop such that when the fruit
is harvested it gives room for the full development of the second.
Strip cropping- This involves sowing more than one crop in
different strips.
Intercropping as previously mentioned has an increased yield
advantage thus useful in poverty and hunger alleviation as an insurance against
crop failure and positive effect on soil properties (Ehigiator and Ikhidero,
1999).
Garden Egg (Solanum aethiopicum)
The name “Garden egg plant” was derived from the shape of
the fruits of some varieties which are white and shaped like chicken eggs (Chen
et al., 2001). The plant (Solanum spp) is a vegetable with increasing
popularity in the world (Pessarakli and Dris, 2003), and it originated from
Tropical Africa (Norman, 1992). It is an economic flowering plant belonging to
the family Solanaceae, of which members of about 1,400 species found throughout
the temperate and tropical regions of the world are mostly herbaceous plants.
The fruit of the plant comes in a wide array of shapes and colours, some are
yellow and small with green stripes; there are the big yellow ones with white
colour and flat ribbed green types among others (Chen et al., 2001). The
importance of the garden-egg cannot be overemphasized. It is consumed on daily
basis by urban families and also represents the main source of income for
producing households in West Africa (Danquah- Jones, 2000). Nutritionally,
garden egg contains water (92.5%), protein (1%), fat (0.3%), and carbohydrates
(6%). They contain between 30 and 50% of iron (Fe), fiber, potassium (K),
manganese (Mn), copper (Cu) and vitamins; thiamin (vitamin B1), B6, folate,
magnesium and niacin. Egg plant also contains phyto-nutrients such as nasunin
and chlorogenic acid (Sabo and Dia, 2009). It is a very good source of dietary
fiber, potassium, manganese, copper and vitamin B6, folate, magnesium and
niacin. Egg plant also contains phyto-nutrients such as nasunin and chlorogenic
acid. It is a valuable vegetable for canning industries for garden-egg paste,
sautéed garden-egg and other products. The fruits are fried, stewed, marinated
and prepared in other ways. The garden egg plant with its bitter taste and
spongy texture could really make an amazing pot of stew with a nice aroma. When
eaten with boiled yam or rice, it becomes a delicacy you do not want to miss at
the slightest opportunity. Medicinally, they are processed and used in the
preparation of condiments and products used in treating different diseases and
health problems (Burkill, 1985). A meal of garden egg is proven to be of benefits
to patients suffering from raised intraocular pressure (glaucoma) and
convergence insufficiency, as well as in heart diseases and Arteriosclerosis
(Harish et al., 2008). The plant can be regarded as a brain food because it
houses the anthocyanin phytonutrient found in its skin, Nasunin, a potent
antioxidant and free radical scavenger that has been shown to protect cell
membranes from damage. Studies have shown that nasunin protects the fats in
brain cell membranes. Nasunin is not only a potent free radical scavenger, but
is also an iron chelator. Iron is an essential nutrient, necessary for oxygen
transport, normal immune function and collagen synthesis, but when it becomes
too much in the blood stream; it becomes a major concern. Excess iron increases
free radical production and is associated with an increased risk of heart
disease and cancer. Menstruating women, who lose iron every month in their
menstrual flow, are unlikely to be at risk, but in post-menopausal women and
men, iron, which is not easily excreted, can accumulate. By chelating iron,
nasunin lessens free radical formation with numerous beneficial results
including protecting the blood cholesterol from peroxidation, preventing
cellular damage that can promote cancer, and lessening free radical damage in
joints, which is a primary factor in rheumatoid arthritis. The predominant
phenolic compound found in garden eggs is chlorogenic acid, which is one of the
most potent free radical scavengers found in plant tissues. The chlorogenic
acid performs antimutagenic (anticancer) activities in the body. It also
performs anti- LDL (bad cholesterol) activities by increasing the levels of HDL
(good cholesterol) in the body and at the same time has antiviral and
antimicrobial properties. Consuming high amounts of garden eggs have been found
to be beneficial for people with glaucoma because it lowers the eye pressure.
Egg plant contains measurable amounts of oxalates which are naturally occurring
substances found in plants, animals, and human beings. When oxalates become too
concentrated in body fluids, they can crystallize and cause health problems.
For this reason, individuals with already existing and untreated kidney or gall
bladder problems may want to avoid eating egg plant. Chewing thoroughly while eating,
can enable you get significant benefits, including absorption of calcium from
calcium-rich foods plant foods that also contain oxalic acid. As such, eating
garden eggs does not stop you from meeting your calcium requirements. Egg plant
is low in calories and high in fibre. The egg plant is good for carbohydrate
counters and dieters can actually snack on garden eggs in-between meals.
Production of garden-egg is highly concentrated with 85% of
the output coming from five (5) countries.
Presently, China is the world largest producer (56% of
garden-egg output), followed by India (26%), Egypt, Turkey and Indonesia.
Meanwhile, more than 2,048,788ha are devoted to cultivation of garden egg (FAO,
2008). In the United State of America, Georgia is the largest producing State.
African garden-egg is one of the most commonly consumed fruit vegetable in the
Tropical Africa, in quantity and value and probably, the third after
Lycopersicum esculentum (tomato) and Alum cepa (onions) and before Okra.
According to Girth et al. (1989), a rough estimate for a few countries
indicates an annual production of 8,000 tonnes in Senegal, 60,000 tonnes in
Cote d’ Ivoire and 4,500 tonnes in Burkina Faso.
In Nigeria, garden egg is a very important vegetable crop
grown on commercial scale in some parts of the country. However, the small
scale growers account for at least 86% of the total production. In the South
-East of Nigeria, specifically, in Abia State, garden-egg popularly called
“Mikimiki “ (big sized green fruit with very deep and sweet “endocarp”) is
grown commercially while in the savannah zone of Nigeria; the yellow, white and
thick green skinned varieties are grown on large scale.
Fluted Pumpkin (Telfairia Occidentalis)
This leafy vegetable belongs to family Cucurbitaceae. The
term fluted is used in description of the female flower which has a flute like
appearance. It is believed to be indigenous to East, central and west Africa
between latitude 7oS and 5oN and longitude 2oE and 38oN (Howes 1950). In
Nigeria, it is referred to as Ugu by Igbos, Iroko by the Yorubas, Ubon by the
Efiks. Its largest diversity in plant population can currently be found in Imo
State and other surrounding areas in South-East Nigeria. Pumpkins are largely
grown for their leaves which are used as vegetables and its fruit which is
boiled and eaten as desert (Attere 1984).
The fluted pumpkin is a perennial dioecious crop although
monoecious forms also exist. The female plants have distinctly stronger shoots
and stronger shoots and larger leaves than male plants. The male plants
however, flowers about 5 months from sowing while it takes the female plants
another 3 weeks before its first flower is open ( Chigwe and Saka 1994).
Pumpkin seeds contain 20-55% oil rich in unsaturated fatty
acid oleic and linoleic acid and 23-25% protein, rich in arginine, aspartate
and glutamine but they are deficient in lysine and sulphur containing amino
acids. Pumpkin seeds can be eaten in the dry season as snack after roasting or
grinding into butter (Gwanan and Nitcherlein 1995).
Pumpkin also contains high levels of copper, Iron and
Vitamin A Chandarasckhar et al (2000) reported that pumpkin leaves had the
highest amount of beta-carotene in a form that promoted its absorption in
adults, among selected green vegetables. Despite the importance of pumpkin in
the small holder sector in Southern Africa, little research has been done on
this crop (Chigwe and Saka 1994).
According to a research carried out by Ehigiator (1994) and
Edo ADP crops grown in mixture by farmers in Edo State were in the order
Maize + cassava
Maize + egusi
Maize + egusi + cassava
Yam + maize + mellon
Yam + maize + egusi mellon + vegetable
Maize + cassava + cowpea
Despite the growing of these crop mixtures by farmers,
little is understood on the effect of various crop components in an intercrop.
Due to the importance of okro as a staple food crop and of fluted pumpkin in
the diet of people in Nigeria, hence this study on the intercropping effect of
both crops on their productivity in an ultisol in Benin City, Nigeria.