CHAPTER ONE

1.0 INTRODUCTION

1.1 Background of study

Maize (Zea mays L.) is a very important crop in the

tropics grown for a lot of purpose ranging from direct

consumption by man and animals to various industrial

uses (Powell et al., 2004). The production of maize in

Southern Nigeria has being in the decline for some

decades now (Eleweanya et al., 2005). Part of this decline

has been attributed to soil acidity problem in the area

(Pandey et al., 1994), which has reduced the soil pH to

less than 5.5 (Ahn, 1993).

Maize can be grown successfully on soils with a pH

of 5.0 – 7.0 but a moderately acid environment of pH

6.0 – 7.0 is optimum (Khanna and Raison, 2006). Outside1

the range results in nutrient deficiency and mineral

toxicity (Khanna and Raison, 2006). In order to

ameliorate this problem of soil acidity, ash is added

to the soil so as to reduce soil acidity, improve soil

fertility and also help the soil release certain

nutrients (Khanna and Raison, 2006). Some of these

nutrients include; Nitrogen (N), Phosphorus (P),

Calcium (Ca) and Magnesium (Mg). Maize can be grown on

a wide variety of soil, but perform best on well

drained, well aerated, deep warm loams and silt loams

containing adequate organic matter and well supplied

with available nutrients. Although it grows on a wide

range of soils, it does not yield well on poor sandy

soils except with heavy application of fertilizer and

on clay soils, it does not tolerate water-logging, it

2

can be killed if it stands in water for as long as two

days (Khanna and Raison, 2006).

Light is a visible form of electromagnetic wave.

It makes it possible for plants to grow and produce the

food we eat. Plants derive this energy from sunlight by

means of photosynthesis. The characteristics of light

such as intensity, quality (color) and duration

determine to some extent the level of its interaction

with matter. Intensity of incoming radiation from the

sun is altered by both atmospheric and terrestrial

obstruction. A host of researchers (Ballare et al., 1991,

Baraldi et al., 1994 and Grantani, 1997) have shown that

change in spectral energy distribution affect plant

growth and development. Photoreceptors in plants are

divided into two: phytochrome principally sensitive to

3

light in the red and far-red regions of the visible

spectrum (Batschaver et al.,1998; Ballare, 1999 and Smith,

2000) and crytochrome and phototropin sensitive to blue

light (Briggs and Huala, 1999). Most plants use the

photoreceptors to regulate the time of flowering,

germination of seeds, elongation of seedlings, size and

shape of leaves, number of leaves, the synthesis of

chlorophyll and stomata opening (Gay and Hurd, 1975;

James and Bell, 2000; Henning, 2001 and Answer, 2006).

Photosynthesis is the process by which green

plants and certain other organisms (seaweeds, algae and

certain bacteria) use the energy of light to convert

carbon dioxide and water into simple sugar (Leal,

2007). Light energy causes the electrons in chlorophyll

and light-trapping pigments to boost up the electrons

4

only out of their orbits, the electrons instantly fall

back into place releasing vibration energy as they go,

all in millionths of a second. Chlorophyll and the

other pigments absorb the energy released by the

electrons which is used during photosynthesis. Plants

from different environments have different responses to

colors of light. Branching, internodes length and

flowering initiation can all be affected by varying

degrees by the ratio of red light to far-red.

Therefore, it can be clearly seen from existing

literatures that light affects almost all processes

associated with growth, photosynthesis and flowering in

plants. The optimum temperature for plant growth and

development ranges from 30oC – 34oC. The cool

conditions at high altitude lengthen the cycle or

5

growing period. Temperatures below 5oC and above 45oC

results in poor growth and death of maize plant.

1.2 Objectives of study

This experiment aim at investigating the growth

performance of maize on different soil types treated

with plant ash and subjected to different light

intensity.

6

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 Taxonomy

Maize is the most important cereal in the world

after wheat and rice. It is unique among cereals. The

grains are borne in separate inflorescence, which are

completely enclosed as modified leaf sheaths or husk,

7

so that it is incapable of dispersing its sheets. The

genus Zea belongs to the tribe Andropogoneae in the

subfamily Panicoidea in the family Poaceae (Reviewed in

OECD, 2003 and USDA, 2005). There are currently eighty-

six (86) recognized genera within the Andropogoneae

tribe (USDA, 2005). Currently, there are five species

included in the genus Zea. Species of Zea that have been

examined, largely have a chromosome number of 2n = 20,

except for Z. perennis (perennial teosinte with 2n =

40) (as reviewed in Ellneskog-Staam et al., 2007). The

species Z. nicaraguensis was described by Bennett et al.

(2003), it is closely related to Z. Luxurians but

currently, the number of chromosomes and sexual

compatibility with other Zea spp are unknown.

8

2.2 Morphology

2.2.1 Plant morphology

The typical maize plant is a tall (1-4m) annual

grass (monocot) which forms a seasonal root system

bearing a single erect stem (culm) made up of nodes and

internodes, although some cultivars may develop

elongated lateral branches (tillers). Many temperate

cultivars are shorter than tropical (and subtropical)

cultivars. Nodes gradually taper to the top of the

plant. Leaves are broad and a single leaf develops at

each node in two opposite ranks, the leaf arrangement

is distichous (reviewed in Esau, 1977). Each leaf

consists of a sheath surrounding the stalk and an

expanded blade connected to the sheath by the blade

joint. The mature plant can have up to approximately

9

thirty leaves, with considerable variation in leaf

number, size and orientation between maize races.

Generally, tropical maize plants develop more leaves

than temperate cultivars. Maize, like many plants that

evolved under tropical conditions is a C4 (that is,

Hatch and Slack cycle) plant and therefore, more

efficient at utilizing carbon dioxide than C3 (Calvin

cycle) plants. The physiological characteristics are

reflected in leaf morphology down to the microscopic

level. For example, bundle sheath cells are richer in

chloroplasts than mesophyll cells. The chloroplasts are

also larger than those of mesophyll cells (Reviewed in

Esau, 1977).

2.2.2 Reproduction morphology

10

Maize is a monoecious plant: one or more lateral

branches, the shanks develop in the leaf axis of the

plant. They terminate in a female inflorescence, an

ear. The male inflorescence, the tassel, forms at the

top of the stem. Usually one or two lateral shoots in

the upper part of the plant develop into female

inflorescences. The shank consists of nodes and short

internodes, the lengths of which vary between maize

races. The ear is covered in a number of leaves called

husks. Those leaves differ in appearance when compared

to those on the stalk; they surround and protect the

developing ear. Where maize is left to dry in the

fields, more husks are generally desired to protect the

grains from birds and insects. Where maize is harvested

earlier, it is often desirable for a cultivar to have a

lower number of thin husks. The ear does not usually11

show any lateral branching. The thick axis of the ear

the cob, bears an even number of rows of ovaries, each

containing a single ovule .The number of ovules that

will develop into kernels ranges from three hundred to

one thousand and is dependent on the cultivar/variety

as well as factors occurring later in development

(Purseglove, 1972). The silks of the maize ear are the

stylar canals of the mature ovaries.

2.3 Forms of maize

A number of maize can be described on the basis of

endosperm and kernel composition (Paliwal, 2000 and

Darrah et al., 2003).

1. Flint maize: Flint maize kernels are

characterised by their high percentage of hard

endosperm around a small soft centre.

12

2. Dent maize: It is the most commonly grown for

grain and silage, and is the predominant type grown in

the U.S.A. Hard endosperm is present on the sides and

base of the kernel. The remainder of the kernel is

filled with soft starch, when the grain starts drying

the soft starch at the top of the kernel contracts,

producing the depression for which it is named.

3. Floury maize: Is being grown predominantly in the

Andean region. Its endosperm is mainly composed of soft

starch, making it easy to grind and process into foods.

4. Waxy maize: Waxy maize kernels contain almost

entirely amylopectin as their starch (rather than the

normal 70% amylopectin and 30% amylose). Waxy maize is

preferred for food in some part of East Asia and for

some industrial uses.

13

5. Pop maize: Pop maize kernels are characterised

by a high proportion of hard endosperm, which is much

higher than any other maize kernel. Pop maize is grown

on a small scale compared to other types but popped

kernels are consumed worldwide as a snack food

(Reviewed in Ziegler, 2003).

6. Sweet maize: Is grown for green ears (sweet

corn). The ears are harvested at approximately eighteen

to twenty days post pollinated when kernel moisture is

approximately seventy percent (70%). The developing

grain of sweet maize is higher in sugar content due to

one or more recessive mutations blocking conversion of

sugar starch.

7. Baby maize: The unfertilized young ear obtained

from sweet maize or other forms of maize is called baby

14

maize. This is rich in minerals and vitamins and can be

harvested within forty-five to fifty days after sowing

for marketing.

2.4 Reproduction

2.4.1 Asexual reproduction: Under natural condition

maize reproduces only through seeds

2.4.2 Sexual reproduction

Maize is a quantitative short-day plant but some

cultivars have low or no sensitivity to day-length

(Kiniry et al., 1983). In those cultivars that are

photoperiod sensitive, flowering may be delayed when

the photoperiod is greater than a critical threshold

15

value ranging from 10 – 13.5h (Kiniry et al., 1983). Those

adapted to the tropics may show delayed maturity if

grown in more temperate areas with longer days (Birch

et al., 2003). Initially male and female inflorescences

have primordia of bisexual flowers. However, during

their development, primordia of stamens abort in the

axillary inflorescences, the primordia of gynoecia

abort in the apical inflorescence. The apical meristem

elongates once the leaf premordia are initiated. It is

transformed into a reproductive meristem that develops

into the tassel. Pollen is shed from the tassel

continuously for a week or more as upper and lower

florets in the male spikelets show developmental

differences and the spikes mature asynchronously. The

female inflorescences (ears) arise from axillary buds

and bear flowers in rows along the cob. Development of16

the flowers and the ovules on the ear proceeds from the

base upwards (acropetal). From each flower a style

begins to elongate towards the tip of the cob, forming

long threads, or silks. Silk development begins from

the flowers near the base of the ear and proceeds

towards the tip over several days. Receptive silk

emerge over the husks over a period of three to five

days and can grow to more than 30.5cm length, extending

beyond the end of the husks. The silks have short

hairs, trichomes, which form an angle to the stylar

canals and help harboring pollen grains. Receptive

silks are moist and sticky. Maize is often considered

as protandrous (anthers reaching maturity before he

gynoecium), as anthers on the spikelets on the upper of

the central spike protrude out of the florets and start

shedding pollen one or two days (under optimal growth17

conditions) before the silk emerge above the husks.

However, the gynoecium matures and the silks become

receptive before they appear above the husk tips. Under

any stress (especially water stress), the interval

between pollen release and silk emergence increases.

2.5 Abiotic interactions

Maize plant shows wide genetic base for abiotic

stress tolerance, which is mirrored by its ability to

grow in a variety of environments. Although, it is

essentially a crop of warm climates with adequate

moisture (Purseglove, 1972) and is therefore not suited

to semi-arid or wet tropical climates. It is argued

that genetic improvement in maize yield over the past

seventy years is the result of changes to physiological

attributes that, in turn, have imparted enhanced

18

abiotic stress tolerance (Lee and Tollenaar, 2007) that

is, selection of hybrids for high density planting has

been accompanied by increased resistance to stresses

like drought and has permitted consistent performance

across a range of variable environments (Dhugga, 2007).

One way that abiotic stress affects the maize plant is

by moving the source-sink balance (Lee and Tollenaar,

2007). Classic symptoms of excess source capacity are

purpling of leaves, sheath tissues and stalks during

grain-filling while symptoms of excess sink capacity

are premature senescence of leaves and stalks during

grain-filling (Lee and Tollenaar, 2007).

2.5.1 Nutrient requirements

Maize grown commercially, whether for grain or

silage, has a high demand for nutrients, especially

19

Nitrogen (N), Phosphorus (P) and Potassium (K) (Birch

et al., 2003). In maize-growing areas of the tropics,

acids soils are widespread and plant growth is

constrained by the associated Aluminum toxicities that

lead to stunting and impairment of root growth and

subsequent inability of plants to take up moisture from

the soil (Lafitte, 2000).

2.5.2 Temperature requirements and tolerances

Maize is a summer-growing crop requiring warm day

time temperatures of between 250C – 300C and cool

nights (Colless, 1992). Temperature below 80C (or 00C

after silking) or above approximately 400C usually

cause cessation of development (Birch et al., 2003).

Different maize cultivars have different optimal

temperature requirements and, for example, tropical

20

cultivars derived from highland maize are better able

to grow and develop at lower temperatures than those

adapted to ‘lowland’ or ‘mid-altitude’ areas.

Temperatures that are outside the range of adaptation

of a cultivar may impact negatively on factors such as

photosynthesis, translocation and pollen viability. In

particular, high temperatures have negative impact on

the kernel growth, kernel mass and protein accumulation

(Monjardino et al., 2006).

Table 2.1Effects of temperature on key processes inmaize

Temperature Process EffectHightemperature

Photosynthesis Reduced above 400C due tomembrane damage,irreversible damage above

21

45oCRoot hormoneproduction(Abscisic acidand cytokinin)

Reduced hormone productionrestricts chloroplastdevelopment andphotosynthetic activity

Pollination Pollen viability reducedabove 350C especially ifthere is low humidity

Grain yield Grainfilling duration isreduced, grainfilling rateis increased. Overallyield is reduced.Exacerbated by waterstress

Lowtemperature

Photosynthesis Reduced due to reducedenzyme function andmembrane damage

Leaf extension Reduced due to reducedenzymes function andmembrane damage

Water andnutrientuptake

Reduced due to reducedenzyme function andmembrane damage in roots.

Grain yield Reduced, especially intropical lowland cultivarsat less than 150C.

Translocation Reduced, especially intropical lowland cultivarsat less than 100C

Source: Lafitte(2000).

22

2.5.3 Water

2.5.3.1 Water deficiency

Worldwide, the average yield losses in maize crops

due to drought can be high, particularly in the tropics

(Srinivasan et al., 2004). Rainfall is a limiting factor

for dry-land production of commercial maize crops and

irrigation is essential in areas with a winter dominant

rainfall pattern or where the amount of summer dominant

rain is high variable (Birch et al., 2003). Maize is

particularly susceptible to water stress at the

flowering stage when yield potential is being set23

(Srinivasan et al., 2004) especially as this coincides

with high evapotranspiration rates.

2.5.3.2 Water-logging

Significant annual losses in maize production can

occur because of water-logging (Srinivasan et al., 2004).

Plants growing for prolonged periods in waterlogged

soils show stomatal closure, reduced leaf area growth,

chlorosis, reduced root growth, root death and

ultimately plant mortality (Srinivasan et al., 2004).

Damage to roots is due mainly to the accumulation of

toxic products (such as lactic acid) as a result of

anaerobic respiration. Tropical and subtropical

cultivars are most susceptible to water-logging at the

early vegetative stage and at “knee high” stage

(Srinivasan et al., 2004). Molecular and cellular changes

24

to maize seedlings under short-term water-logging has

been widely studied as maize typically shows an

anaerobic “response” in which some twenty proteins,

mostly associated with glycolysis or sugar-phosphate

metabolism, are synthesized (Subbaiah and Sachs, 2003).

Root porosity, that facilitates oxygen diffusion from

the above ground parts to the submerged roots, is

increased by the selective death of root cortical cells

and helps to prolong the survival of plants (Subbaiah

and Sachs, 2003). Root tip death, also characteristic

of response to anoxia, may enhance survival and

subsequent recovery, when water-logging is removed by

eliminating an area of metabolically active tissue

(Subbaiah and Sach, 2003). Development of adventitious

root on the soil surface is also important in

conferring flooding tolerance (mano et al., 2005).25

2.6 Biotic interaction

2.6.1 Weeds

Although, maize is a vigorous and tall growing

plant, it is susceptible to competition from weeds,

particularly at the early stages of growth (Morris,

2008). Weeds may directly lead to yield reduction by

competing with the maize plant for nutrients and water

(James et al., 2000). Weed management can take a number of

forms with an integrated approach being recommended

(Farell and O’Keeffee, 2007) and including crop

rotations, planting into weed-free seedbeds, pre-plant

cultivation, use of pre-plant/pre-emergence/post-

emergence herbicides (O’Gara, 2007). A range of

herbicides offer flexible options for weed control and

often two herbicides can be used in combination to give

26

a broader spectrum of control (O’Gara, 2007). Commonly

used herbicides include atrazine, flumetulan, dicamba,

metolachlor, fluroxypyr, propachlor, pendimethalin,

tribenuronmethyl and triclopyr (Storrie et al., 2005).

2.6.2 Insects

Maize is most susceptible to damage by insects

during the establishment phase when soil insects can

cause up to 30% losses and necessitate replanting of

the crop, and from tasselling to harvest (O’Gara,

2007). Invertebrate pest establishing crops damage

germinating seeds and seedlings and include black field

earwigs, wireworms, false wireworm, cutworms, maize

stem borer, and beetles such as African black beetle.

The recent development of insecticidal seed treatments

(examples, imidicloroprid and thiamethoxam) has help to

27

control soil pests and some above ground insects

(O’Gara, 2007).While more traditional methods such as

in-furrow spraying and agronomic practices at sowing

are also effective (Hughes, 2006).

2.7 Nutritional components of maize kernel

The typical mature kernel as a whole is composed

of 70-75% starch, 8-10% protein and 4-5% oil (Boyer and

Hannah, 1994). However, there are large differences in

the relative concentrations of these components between

different parts of the kernel. The two major structures

of the kernels are the endosperm and the germ (embryo),

constituting about 80% and 10% of the mature kernel dry

weight, respectively. The endosperm is largely starch

(approximately 90%) while the germ contains high levels

28

of fat (approximately 33%) and protein (approximately

18%).

Table 2.2 Relative content (%) of nutrient componentsin parts of the maize kernel

Nutrient Pericarp/Seedcoat

Endosperm Germ(embryo)

Protein 3.7 8.0 184Crude fibre 86.7 2.7 8.8Crude fat 1.0 0.8 33.2Starch 7.3 87.6 8.3Sugar 0.34 0.62 10.8

Source: FAO(1992).

2.8 Beneficial phytochemicals

Maize is considered an important food crop for

humans and a high-energy feed for animals (FAO, 1992).

In humans diet it is a good source of vitamin B1, B5,

29

folate, dietary fibre, vitamin C, phosphorus and

manganese and as a staple food it compares favourably

with root and tuber crops and is similar in energy to

dried legumes (Okuruwa and Kling, 1996). The average

nutritional content of various forms of maize is given

in Table 2.2; processing reduces the concentration of

proteins, lipids and fibres (FAO, 1992).

Table 2.3Ranges for proximate analysis of maize grain,sweet corn kernels and silage

Maizegrain

Sweetcorn

Maizesilage

Moisture % freshweight

7-23 74.7-84 62-78

Protein % dryweight

6-12 11.3-15.6 4.7-9.2

Lipid % dryweight

3.1-5.8 4.86-8.75

Ash % dryweight

1.1 – 3.9 2.58-3.86 2.9-5.7

Carbohydrate

% dryweight

82.2-82.9 72.5-79.18

Fibre % dryweight

8.3-11.9 11.2-15.6 40-48.2

30

Source: OECD (2002).

2.9 Commercial uses

Maize is one of the oldest cultivated grains and

one of the most productive crop species with a global

average yield of more than four tonnes per hectares

(Reviewed in Paliwal, 2000 and Farnham et al., 2003). It

can be directly consumed as food at various

developmental stages from baby corn to mature grain. A

high proportion of maize produced is used as stock

feed, for example, 40% in tropical areas and up to 85%

in developed countries (Reviewed in Paliwal, 2000 and

Farnham et al., 2003). It can be fed to stock as green

31

chop, dry forage, silage or grain. Various fractions of

milling processes can also be used as animal feed.

Stover is the term used to describe the dried stalks

and leaves of a crop used as animal fodder after the

grain has been harvested. Maize can be processed for a

range of uses both as an ingredient in food or drink,

for example corn syrup in soft drinks or maize meal or

industrial purposes. Maize is the major source of

starch worldwide and is used as a food ingredient,

either in its native form or chemically modified

(White, 1994). Maize starch can be fermented into

alcohol, including fuel ethanol, while the paper

industry is the biggest non-food user of maize starch.

The oil and protein are often of commercial value as

by-products of starch production and are used in food

32

manufacturing (Boyer and Hannah, 1994; Paliwal, 2000;

Hobbs, 2003 and McCutcheon, 2007).

2.10 Effects of light on plant growth and development

Light is made up of energy. Light to plants is the

wavelengths of the electromagnetic spectrum. Light for

plant is used for producing food through the process of

photosynthesis (Bjorn, 1994). The characteristics of

direction and spectral composition of light in the

plants environment is transferred to the plant through

the interception and activation of pigment systems

within the leaf. Plants also use light for sensing and

detecting competitors and keeping track of time (Bjorn,

1994).

2.10.1 Light quality

33

Sunlight is often referred to as white light and

is composed of all colors of light (Bjorn, 1994). A

color of light would be the relative distribution of

wavelengths from a radiation or reflective source.

2.10.2 Light intensity

Light intensity is a major factor governing the

rate of photosynthesis. The quantity or amount of light

received by plants in a particular region is affected

by the intensity of the incident (incoming) light and

the length of the day (Bjorn, 1994).The intensity of

light changes with elevation and latitude. The amount

of sunlight also varies with the season of the year and

time of day, as well as other factors, such as clouds,

dust, smoke or fog. Plants have varying preferences for

light intensity. The light saturation point of the

34

plant determines the relative light requirement of

plant (Bjorn, 1994). The light saturation point is the

point above which an increase in light intensity does

not result in an increase in photosynthetic rate. Crops

such as maize etc. require a relatively high level of

light for proper plant growth (Bjorn, 1994).

2.10.3 Light duration

Due to the tilt of the earth’s axis (23oC from

vertical, that is,

the inclination angle of a planets rotational axis in

relation to its orbital plane) and its travel around

the sun, the length of light period (also called

photoperiod or day-length) varies according to the

season of the year and latitude. It varies from a

nearly uniform twelve-hour (12h) day at the equator (O

35

latitude) to continuous light or darkness throughout

the twenty-four hours (24hrs) for a plant of the year

at the poles (Bjorn, 1994). Some plants change their

growth in response to day-length and exhibit

photoperiodism. One important plant response to day-

length in some plants is flowering. Some plants flower

when a specific day-length minimum has been passed.

Short day plants flower rapidly when the days get

shorter and long day plants flower fast when days get

longer. Plants that are not affected by day-length are

called neutral plants. These plants can flower under

any light period (Bjorn, 1994).

2.10.4 Light energy captured by plants

(Photosynthesis)

36

One of the main roles of light in the life of

plants is to serve as an energy source through the

process of photosynthesis using water and carbon

dioxide, through photosynthesis; plants produce the

foodstuff (photosynthate) necessary for growth and

survival. Subsequently, carbohydrates (starch and

sugar) and stored chemical energy are produced during

biochemical processes in plants (Bjorn, 1994). Plants

capture the energy in light using a green pigment

called chlorophyll. A very precise number of photons at

specific wavelengths (near 680nm) are required to split

a water molecule (H2O) within the green leaf, which

releases oxygen (O2) and provides chemical energy to

continue the long biochemical process to produce more

complex molecules such as carbohydrates. Carbon dioxide

37

from the air and water from within the leaf combine to

produce oxygen and photosynthates (Bjorn, 1994).

2.10.5 Light regulated plant development (Photo-

morphogenesis)

Photo-morphogenesis is defined as the ability of

light to regulate plant growth and development,

independent of photosynthesis. Plant process that

appear to be photomorphogenic include internode

elongation, chlorophyll development, flowering,

abscission, lateral bud outgrowth and root and shoot

growth (Bjorn, 1994). Photo-morphogenesis differs from

photosynthesis in several major ways. The plant pigment

responsible for light-regulated growth response is

phytochrome. Phytochrome is a colorless pigment that is

in plants in very small amounts. Only the red (600 to

38

660nm) and far red (700 to 740nm) wavelengths of the

electromagnetic spectrum appear to be important in the

light-regulated growth of plants. The wavelengths

involved in generating photosynthesis are generally-

broader (400 to 700nm) and less specific. Photo-

morphogenesis is considered a low energy response

(meaning that it requires very little light energy to

get a growth-regulating response). Plant generally

require greater amount of energy for photosynthesis to

occur (Bjorn, 1994).

CHAPTER THREE

3.0 MATERIALS AND METHODS

39

3.1 Study site

The experiment was carried out in 2013, from the

11th of June to the 19th of August at the Botanical

garden behind the Department of Microbiology site II,

Delta State University, Abraka, Delta State. Abraka

lies between Latitude 5O45’ and 5O50’ North of the

Equator and Longitude 6O and 6O15’ East of the

Greenwich meridian (Efe, 1994). Abraka falls between

the equatorial climate belt of Nigeria with mean

temperature of 30OC, the area is characterised by a

total annual rainfall of three hundred and ninety-eight

millimeters (398mm) with mean annual rainfall ranging

from two hundred and eighty-eight millimeters (288mm)

in December to six hundred and twenty eight point nine

millimeters (628.9mm) in September (Efe, 2006).

40

3.2 Sample collection

3.2.1 Source of seeds

The maize variety; composite maize was purchased

from Agricultural Development Programme (A.D.P.)

Effurun, Delta State, Nigeria.

3.2.2 Source of soil sample

Sandy soil was obtained from Abraka River (Ken-

dive) at Abraka, Ethiope-East Local Government Area of

Delta State, Nigeria. The other soil samples (loamy,

laterite and clay) were collected from a virgin land

from site III, Delta State University, Abraka, Delta

State, Nigeria.

3.2.3 Source of plant ash

41

Fresh grasses were cut at a site behind

Microbiology laboratory, site II, Delta State

University, Abraka, Delta State, Nigeria, they were

dried under natural condition and later burnt.

3.3 Experimental design

Randomized Complete Block Design (RCBD) with three

replications was used for the experiment.

3.4 Procedure

Five kilograms (5kg) of each of the soil samples

(loamy, sandy, laterite and clay) were measured and

filled into the polythene bags (37 × 33cm in dimension)

with a total of thirty-six polythene bags and they were

perforated to allow easy drainage of water. Seeds were

planted at a depth of 2cm into each of the polythene

bags and watered immediately and afterwards, every42

other day at 200ml. The experiment was replicated three

times and arranged in Randomized Complete Block Design

(RCBD) into the net that is, triple net (5 × 3 ft) and

the no-net and control were left outside. 5.56g of

plant ash was measured with an electronic compact scale

(g) and added to the plant one week after planting and

the setup was monitored for ten weeks and parameters

were measured. Germination count was taken per

polythene bag at seven days after sowing, when

germination commenced at day three after exposure to

sunlight for loamy, sandy and laterite while for clay

germination commenced at the 4th day after sowing.

Germination percentage was calculated, thus

% Germination =NumberofseedsgerminatedNumberofseedssown× 100

1

43

This procedure follows that of Edema and Etioyibo,

(2009). Seeds which failed to sprout within the seven

days period were regarded dead.

The growth parameters, leaf area, stem diameter

(girth) and leaf number were determined every two

weeks, the plant height were determined weekly while

sunlight intensity was taken daily. The light intensity

of the plant was determined using a light meter. Plant

height was determined using a meter rule; it was

measured from the soil level to the tip of the youngest

leaf. The leaf area determination was done by measuring

the length and breadth of the leaf and correction

factor of 0.75 was used to multiply the length and

breadth measurement following the procedure of Edema

and Etioyibo, (2009). The girth of the plant was

44

determined using a digital caliper. The number of

leaves was determined by visually counting the number

of leaves per polythene bag. For the dry weight

accumulation, the plants were harvested. These plants

were weighed (fresh weight) and oven dried at 55OC for

88hours following the procedure of Edema and Etioyibo,

(2009).

3.5 Statistical analysis

Data collected were analysed statistically using

One-way Analysis of Variance (ANOVA) and the

significant means were separated with the Duncan

multiple range test using the statistical analytical

system (SAS, 2005).

3.6 Chlorophyll analysis

45

The leaf chlorophyll content was estimated

according to the method of Zhang and Qu (2003). Ten

weeks after planting, the third or fourth leaf from the

apex of the plant from each polythene bag was

harvested, wrapped in a foil paper labeled and put in a

dark polythene bag. A weight of 0.10g of leaf tissues

were taken from each leaf sample and put in a 50ml

labeled McCartney bottles. Twenty millitres (20ml) of

eighty percent (80%) acetone was poured into each

McCartney bottle for the purpose of chlorophyll

extraction. The bottles were transferred to a dark

chamber and left to stand for twenty-four hours. After

extraction, the extracts were read for absorbance at

663 and 645nm wavelength in a spectrophotometer.

46

Chlorophyll content was calculated according to

the following formula:

Chla (mg/g) = 12.2A663−0.86A645XV

aX1000XW

Chlb (mg/g) = (19.3A645 -3.6A663)× Va × 1000 × W

Where a = Length of light path = 1cm

W = Fresh weight of leaf sample

V = Volume of solution

The result is expressed in mg/g FW (fresh weight).

3.7 Physicochemical analysis of soil and plant ash

47

3.7.1 pH: It is a measure of the negative logarithm

of the hydrogen ion concentration present in the

samples.

Apparatus: pH meter, 50ml beaker, 2mm sieve, wash

bottle, weighing balance and glass rod.

Reagent: Distilled water

Procedure

The soil sample was air-dried, grinded and sieved

with a 2mm sieve. Ten grams (10g) of the sieved soil

was weighed into a 50ml beaker. 25ml of distilled water

was added to the soil sample. It was allowed to settle

for thirty minutes, during this period the pH meter was

standardized with a buffer 4, 7 and 9. After thirty

minutes had elapsed, the soil sample in the beaker was

stirred with a glass rod and the pH meter electrode was48

immersed into the mixture. The pH of the solution was

noted (Ibitoye, 2006).

3.7.2 Organic carbon/Organic matter (wet oxidation)

Apparatus: 250ml conical flask, retort stand,

burette, measuring cylinder, 0.5mm sieve, mortar and

pistol.

Reagents:0.1MK2Cr2O7, 0.5M(NH4)2Fe(SO4)6H2O,

Diphenylamine indicator and concentrated sulphuric

acid.

Procedure

The soil sample was grinded to a fine powder. One

gram (1g) of the grinded soil sample was weighed into a49

250ml conical flask and 100ml of 0.1MK2Cr2O7was added.

20ml of H2SO4 was added rapidly and the flask swirled

vigorously for one minute immediately after the

addition of the concentrated acid. Thereafter the

solution was allowed to stand for thirty minutes. 100ml

of distilled water, followed by two drops of

diphenylamine indicator was added. The solution was

titrated against 0.5M (NH4)2Fe(SO4)6H2O in the burette

to a dark greenish end point. A blank titration was

also carried out.

Calculations

% Organic carbon = (B−T )×M×0.003×F×100W

% Organic matter = % organic carbon × 1.724

Where:

50

B = Blank titre value

M = Molarity of (NH4)2Fe(SO4)6H2O used

T = Titre value of sample

F = Correction factor = 1.33

W = Weight of sample = 1g

(Ibitoye, 2006).

3.7.3 Exchangeable bases (Ca, Mg, Na and K)

Apparatus: 250ml conical flask, beaker, burette,

retort stand, electronic shaker, shaking container,

flame photometer.

Reagents:0.2M EDTA, 1MNH4OAC, concentrated ammonia

solution, 2% KCN, 20% KOH, Erichrome black T and

meroxide indicators.

51

Procedure

Five grams (5g) of two millimeters sieved air-

dried soil was weighed into a shaking container, 50ml

of NH4OAC was added. The mixture was shaked in an

electrical shaker for one hour. The mixture was

filtered with a filter paper into a 100ml beaker flask,

10ml of the filtrate was pipetted into a 250ml conical

flask and 50ml of distilled water was added. Thereafter

12.5ml of concentrated ammonia solution and 1ml of 2%

KCN was added. This was followed by three drops of

Erichrome Black T indicator. The solution was titrated

against 0.02M EDTA in the burette to a blue end point.

52

The amount of Ca or Mg present in the soil sample was

computed by using the formula.

Ca or Mg (mMol/100g) = T × M × V1 × 100

V2W

Where;

T = Titre value of the sample

M = Molarity of EDTA used = 0.82M

V1 = Volume of extractant used = 50ml

V2 = Volume of extract used = 10ml

W = Weight of sample = 5g

While Na and K were determined by using a flame

photometer (Udo and Oginwale, 1996).

3.7.4 Nitrogen (N)

53

Procedure

Two grams (2g) of the soil was weighed into a

500ml macro, kjeldahl flask, 20ml of concentrated H2SO4

with one gram of catalyst mixture per sample. The

content was heated on a digestion stand until the

solution becomes clear and soil residue remaining

becomes white. It was heated further for few minutes to

ensure complete digestion. The solution was allowed to

cool and 50ml of distilled water was added, and

filtered into 100ml and made up to a mark-standard was

also prepared before reading with a spectrophotometer

(Esu, 1999).

54

3.7.5 Phosphorus (P) (Bray P-1)

Procedure

Five grams (5g) of the soil which has passed

through two millimeter sieve was weighed into a shaking

bottle, 35ml of extracting solution was added, it was

shaked for one minute and filtered into 250ml conical

flask. Phosphorus (P) was determined calorimetrically,

using spectrophotometer (Obi, 1990).

3.7.6 Exchangeable acidity (H+ and Al)

Five grams (5g) of the soil sample which has

passed through 2mm sieve was weighed into a shaking

bottle, 50ml of extracting solution (KCl) was added, it

was shaked for one hour and filtered into 250ml conical

flask. 200ml of the extract was pipetted into 250ml

conical flask, 100ml of distilled water followed by two55

drops of indicator (phenolphthalein) to a pink color

end point. For Al, it was back titrated using the

formula.

H+ or Al = T × M × V1 ×100

W × V2

Where:

T = Titre value of the sample

M = Molarity of EDTA used = 0.82M

V1 = Volume of extractant used = 50ml

V2 = Volume of extract used = 10ml

W = Weight of sample = 5g

(Ibitoye, 2006).

3.7.7 Particle size analysis (PSA)

Procedure56

Fifty grams (50g) of the soil sample after

passing through 2mm sieve was weighed into a shaking

container, 50ml of sodium hetamaphosphate (calgon) was

added and shake with an electrical shaker for thirty

minutes, after which it was transferred into a 1000ml

measuring cylinder and made up to a mark. It was then

inverted several times and the hydrometer was inserted

and the reading was taken after 40seconds that of the

temperature and blank was also taken, after two hours

the reading of the temperature was also taken, using

the formula.

% Silt + clay = (R40secs - Ra) + Rc + 100

W

% Clay = (R2hours−Rb)+Rd×100W

Where;

57

Ra = 40secs blank hydrometer reading

Rb = 2hours blank hydrometer reading

Rc = 40secs correction factor (temperature ×

0.360)

Rd = 2hours correction factor (temperature ×

0.360)

% Sand + silt + clay = 100

% Silt = (Sand + clay) – clay

Sand = 100 – (Silt + clay)

(Ibitoye, 2006 ).

58

CHAPTER FOUR

4.0 RESULTS

The results obtained from the study are presented

in Tables 4.1- 4.17.

Table 4.1 shows the light intensity (Lux/m2) of Zea

mays at week ten. It was observed that the highest

light intensity occurred in the control while the

lowest light intensity occurred in triple net (TN).

Table 4.2 shows the number of leaves of Z. mays at

week ten. It was observed that plants in loamy soil

(triple-net + ash) had the highest leaf number, whereas

the lowest value was recorded in plants grown in clay

soil (triple-net + ash).

59

Table 4.3 shows the germination (%) of maize (Zea

mays). Germination commenced at the third day for

loamy, sandy and laterite, while for clay germination

commenced at the fourth day.

Table 4.4 shows the height (cm) of maize at week

ten. The highest mean plant value was recorded in loamy

soil (triple-net + ash) while the least mean plant

height value was observed in plants grown in clay soil

(triple-net + ash).

Table 4.5 shows the leaf area (cm2) of maize at

week ten. It was observed that plants in no-net + ash

(loamy soil) were found to have the highest leaf area,

whereas the least value was recorded in plants grown in

clay soil (triple-net + ash).

60

Table 4.6 shows the stem girth (mm) of Z. mays at

week ten. The highest value of stem girth was observed

in loamy soil (triple-net + ash) while the least

value was observed in sandy soil (triple-net + ash).

Table 4.7 shows the physicochemical characteristic

of plant ash before planting. The data showed that the

pH of the ash was basic (10.08) and it also contained

important nutrients necessary for growth.

Table 4.8 shows the physicochemical analysis of

soil before planting. It was observed that all the

soils were acidic and also that loamy soil contained

more nutrient than any other soil.

Table 4.9 shows the fresh weight (g) of Zea mays at

week ten. The highest value was recorded in loamy soil

61

(triple-net + ash) while the least value was recorded

in clay soil (triple-net + ash).

Table 4.10 shows the dry weight (g) of Z. mays at

week ten. The highest value was recorded in loamy soil

(no-net + ash) while the least value was recorded in

sandy soil (triple-net + ash).

Table 4.11 shows the physicochemical

characteristics of soils in control after planting.

Table 4.12 shows the physicochemical

characteristics of soil exchangeable bases and acidity

in control after planting.

Table 4.13 shows physicochemical characteristics

of soils in no-net + ash after planting.

62

Table 4.14 shows the physicochemical

characteristics of soil exchangeable bases and acidity

in no-net + ash after planting.

Table 4.15 shows the physicochemical

characteristics of soils in triple-net + ash after

planting.

Table 4.16 shows the physicochemical

characteristics of soil exchangeable bases and acidity

in triple-net + ash after planting.

Table 4.17 shows the chlorophyll content of Zea

mays at week ten.

Table 4.1 Light intensity (Lux/m2) at week ten

Weeks Control No net + ash Triple net +ash

1 583.71a 517.00b 187.00c

2 520.43a 455.00b 216.00c

3 345.14a 304.14b 153.43c

63

4 288.00a 277.57b 158.71c

5 462.57a 421.29b 192.29c

6 478.00a 445.57b 173.00c

7 328.71a 306.29b 152.29c

8 284.43a 273.86b 98.29c

9 181.43a 163.14b 59.29c

10 186.57a 178.43b 66.14c

Means with different alphabets within different columnsare significantly different at P ≤ 0.05 using Duncan’smultiple test.

64

Table 4.2 Number of leaves at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 4.60a 4.73a 4.74a

Sandy 4.13c 4.07d 3.28b

Laterite 4.27b 4.13c 3.20c

Clay 3.53d 4.46b 3.14d

Means with the same alphabets within the same columnare not significantly different at P ≤ 0.05 usingDuncan’s multiple test.

65

Table 4.3 Percentage germination of maize

Day Numberof seeds sown

Number of seed germinated/CONTROL

Number of seeds growth/No net + ash

Number of seeds germinated/ triplenet + ash

L S LT C L S LT C L S LT C1 3 0 0 0 0 0 0 0 0 0 0 0 02 3 0 0 0 0 0 0 0 0 0 0 0 03 3 2 2 2 0 3 2 2 0 3 2 3 04 3 3 2 3 2 3 3 3 2 3 2 3 15 3 3 3 3 2 3 3 3 3 3 2 3 26 3 3 3 3 2 3 3 3 3 3 2 3 27 3 3 3 3 2 3 3 3 3 3 2 3 2%Germ

100%

100%

100%

100%

66.7%

100%

100%

100%

100%

100%

66.7%

100%

66.7%

* L – Loamy

S – Sandy

LT – Laterite

C – Clay

66

Table 4.4 Plant height (cm) of Zea mays at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 47.29a 52.89a 55.91a

Sandy 40.33c 39.43c 37.46c

Laterite 41.42b 42.99b 39.18b

Clay 31.69d 36.98d 29.33d

Mean with different letters within the same column aresignificantly different at P≤ 0.05 using Duncan’smultiple range test.

67

Table 4.5 Leaf area (cm2) of Z. mays at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 76.19a 98.70a 66.69a

Sandy 54.46c 49.61c 34.07c

Laterite 59.87b 62.85b 40.25b

Clay 40.34d 41.74d 28.15d

Means with different letters within the same column aresignificantly different at P ≤ 0.05 using Duncan’smultiple range test.

68

Table 4.6 Stem girth (mm) of Zea mays at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 4.95a 5.54a 5.91a

Sandy 4.37c 4.32d 3.14d

Laterite 4.42b 4.49b 4.48b

Clay 3.23d 4.36c 3.81c

Means with different letters within the same column aresignificantly different at P ≤ 0.05 using Duncan’smultiple range test.

69

Table 4.7 Physicochemical characteristic of plant ashbefore planting

Parameters Units AshPH 10.08% Org. C % 3.09Org matter % 5.33C/N ratio % 6.71Al Mmol/100g 41.30H+ Mmol/100g 27.20Ca Mmol/100g 60.80Mg Mmol/100g 26.40Na Mmol/100g 31.80

70

K Mmol/100g 29.60N % 0.46Avail P Mg/kg 1.77* Org. C - Percentage of organic carbon

*Org matter - Organic matter

*C/N ratio - Carbon/Nitrogen ratio

*Avail P - Available phosphorus

Table 4.8Physicochemical analysis of soils beforeplanting

Parameter

Units Loamy Sandy Laterite

Clay

pH 4.32 4.64 4.98 4.74

71

% Org. C % 2.81 1.94 2.11 1.86Orgmatter

% 4.84 3.34 3.64 3.21

C/Nratio

% 12.77 3.40 7.27 2.90

Al Mmol/100g

3.10 2.80 1.90 2.30

H+ Mmol/100g

4.80 3.90 3.60 2.70

Ca Mmol/100g

4.40 3.60 3.60 3.60

Mg Mmol/100g

4.0 1.20 0.00 2.40

Na Mmol/100g

4.10 3.30 3.60 2.80

K Mmol/100g

0.13 0.11 0.27 2.34

N % 0.22 0.57 0.29 0.64 Sand % 89.08 93.08 83.08 33.08 Silt % 1.52 1.12 1.52 1.52 Clay % 9.40 5.80 15.40 37.40Avail P Mg/kg 1.55 0.11 0.35 0.93

72

Table 4.9 Fresh weight (g) of Z. mays at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 17.20a 19.63a 20.27a

Sandy 14.70b 4.93d 2.33c

Laterite 9.23c 8.10c 2.67b

Clay 2.23d 13.27b 1.67d

Means with different alphabets within the same columnare significantly different at P ≤ 0.05 using Duncan’smultiple range test.

73

Table 4.10 Dry weight (g) of maize at week ten

Soil Control No-net + ash Triple-net +ash

Loamy 3.44a 4.63a 3.37a

Sandy 3.21b 1.04d 0.47d

Laterite 2.46c 2.14c 0.83c

Clay 1.06d 3.83b 1.01b

Means with the same alphabets within the same columnare not significantly different at P ≥ 0.05 usingDuncan’s multiple range tests.

74

Table 4.11 Physicochemical characteristics of soilsin control after planting

Parameter

Units Loamy Sandy Laterite Clay

pH 4.93 4.61 4.46 4.28% Org. C % 3.39 1.05 2.41 1.80

75

Orgmatter

% 5.83 1.80 4.14 3.09

C/Nratio

% 10.94 13.13 34.43 3.27

Sand % 89.08 83.08 83.08 93.08 Silt % 1.52 1.52 29.52 1.12 Clay % 9.40 15.40 37.40 5.80

76

Table 4.12 Physicochemical characteristics ofexchangeable bases and exchangeable acidity of soils incontrol after planting

Parameter

Units Loamy Sandy Laterite

Clay

Al Mmol/100g

1.00 0.35 0.38 0.20

H+ Mmol/100g

1.60 1.10 0.55 0.55

Ca Mmol/100g

0.80 0.80 0.80 0.60

Mg Mmol/100g

1.40 1.60 1.40 0.20

Na Mmol/100g

0.11 0.05 0.19 0.40

K Mmol/100g

0.11 0.05 0.15 0.03

N % 0.31 0.08 0.07 0.55Avail P Mg/kg 57.35 27.45 4.27 40.50

77

Table 4.13 Physicochemical characteristics of soils inno-net + ash after planting

Parameter

Units Loamy Sandy Laterite Clay

PH 4.15 4.51 4.52 5.15% Org. C % 3.45 2.35 2.77 2.35Orgmatter

% 5.93 4.04 4.76 4.04

C/Nratio

% 16.43 10.22 18.47 18.08

Sand % 87.08 85.08 41.08 92.08 Silt % 1.52 1.52 25.52 0.12 Clay % 11.40 13.40 33.40 7.80

78

Table 4.14 Physicochemical characteristics ofexchangeable bases and exchangeable acidity of soils inno-net + ash after planting

Parameter

Units Loamy Sandy Laterite

Clay

Al Mmol/100g

1.20 0.85 0.45 0.35

H+ Mmol/100g

1.45 0.65 0.35 0.35

Ca Mmol/ 1.20 1.60 1.00 1.8079

100gMg Mmol/

100g0.80 1.40 1.00 1.20

Na Mmol/100g

0.19 0.17 0.13 0.05

K Mmol/100g

0.80 0.60 0.12 0.04

N % 0.21 0.23 0.15 0.13Avail P Mg/kg 56.70 11.47 4.05 29.47

80

Table 4.15 Physicochemical characteristics of soilsin triple netted-cage + ash after planting

Parameter

Units Loamy Sandy Laterite Clay

PH 4.20 4.49 4.61 5.12% Org. C % 3.43 2.24 2.79 2.12Orgmatter

% 5.90 4.10 4.40 4.02

C/Nratio

% 12.25 9.33 12.13 15.14

Sand % 89.78 84.31 40.39 93.21 Silt % 1.60 1.58 27.63 1.31 Clay % 8.61 14.11 31.98 5.48

81

Table 4.16 Physicochemical characteristics ofexchangeable bases and exchangeable acidity of soils intriple-net + ash after planting

Parameter

Units Loamy Sandy Laterite

Clay

Al Mmol/100g

1.30 0.82 0.50 0.40

H+ Mmol/100g

1.60 0.56 0.40 0.39

Ca Mmol/100g

1.70 1.30 1.40 1.40

Mg Mmol/100g

1.12 1.00 1.10 0.91

Na Mmol/100g

0.21 0.19 0.11 0.09

K Mmol/100g

0.12 0.08 0.90 0.07

N % 0.28 0.24 0.23 0.14Avail P Mg/kg 55.63 19.42 4.91 36.75

82

Table 4.17 Chlorophyll content of Zea mays at week ten

Soil Tissue

Weight (g)

Wavelength (nm)

Chlorophylla

Chlorophyll b

Total

663 645

Con

tro Loamy 0.10 0.7

30.53 1.69 1.52 3.21

83

lSandy 0.10 0.4

40.43 1.00 1.34 2.34

Laterite

0.10 0.30

0.37 0.74 1.19 1.93

Clay 0.10 0.38

0.40 0.86 1.27 2.13

No-n

et +

ash

Loamy 0.10 0.34

0.38 0.76 1.22 1.98

Sandy 0.10 0.28

0.34 0.63 1.11 1.74

Laterite

0.10 0.47

0.45 1.07 1.40 2.47

Clay 0.10 0.43

0.39 0.98 1.16 2.14

Trip

le-n

et +

ash Loamy 0.10 0.6

50.42 1.51 1.15 2.66

Sandy 0.10 0.36

0.31 0.83 0.94 1.77

Laterite

0.10 0.47

0.42 1.08 1.28 2.36

Clay 0.10 0.64

0.42 1.49 1.16 2.65

84

CHAPTER FIVE

5.0 DISCUSSION

The study on the evaluation of light intensity and

soil nutrients on the growth of Zea mays was

investigated. The treatments used for the experiment

include plant ash, light intensity (triple-net, no-net

and control) and soils (loamy, sandy, laterite and

clay). The parameters include; germination rate, plant

height, leaf number, leaf area, stem diameter, fresh

and dry weight and chlorophyll content.

The results

85

obtained from the study showed that plant ash had a

positive effect on the growth of Zea mays, this may be

due to the basic condition from ash application. There

was delay in germination with clay soil; this may be

due to the compatibility of the soil that reduced the

amount of light absorbed by the plant. Maize performed

best in loamy soil and laterite soil, but poorly in

sandy and clay soils.

The results in Table 4.4 shows that TN (triple-

net) loamy soil had the highest value (55.9cm ± 17.57)

for height after exposure. While TN clay soil had the

least value of 29.33cm ± 9.68. This may be attributed

to the nutrient status of the soil or as result of

plant Etiolation.

86

The results for leaf area and girth of the plant

were 98.70cm2 ± 47.79 and 5.91mm ± 2.67 for TN (loamy

soil). This may also be attributed to the nutrient

status of the soil.

The results obtained from the study showed that

the application of the ash material increased the soil

pH, reduced soil exchangeable acidity, exchangeable

aluminum and exchangeable hydrogen. This is because the

ash material contained basic cations and basic anions

that are able to pull H+ from exchange sites to form

H20 + Co2. Cations occupy the space left behind by H+ on

the exchange. This result is in agreement with Fageria

et al. (2007); Voundi, et al. (1998) and Ojeniyi et al. (1999)

who reported that working with 2, 4, 6 and 8tons per

hectare of ash increased the soil pH. The increase in

87

maize roots in no-net + ash and triple-net + ash was a

result of the ash, which provided basic cations, that

suppressed the toxicity of aluminum in the soil and

this enhanced the activities of the roots by creating a

better environment for the release of phosphorus, which

helps in the development and growth of the plant roots.

Franco and Mumms (1982) reported that increasing the

concentration of calcium in the soil reduced the

aluminum toxicity in bean root. Dierolf et al. (1997) also

reported that application of ash to maize allowed the

roots of maize to move up to 15 to 30cm of depth in an

acid soil. The increase of stem diameter (girth) in no-

net + ash and triple-net + ash could be as a result of

the potassium content of the ash which according to

Chude et al. (2004) is responsible for the development of

the stalks and its deficiency results in weak stalk and88

lodging of the plants. Therefore, the addition of plant

ash impacted positively on the growth parameters of

maize in the soils. As the exchangeable aluminum is

reduced, the plant roots performances were enhanced,

nutrient uptake increased and this in return led to

increase in the seedling of the plant.

5.2 Conclusion/Recommendation

The results of the study showed that the

application of plant ash increased soil pH and reduced

soil exchangeable acidity, which led to increase in

plant height, stem diameter, leaf area, root size and

stalk size of Zea mays. From the results, light

intensity, plant ash and soil types had significant

effect on the growth of maize. This study also showed

that the growth and the development of maize is highly

89

dependent on nutrient rich soils and optimum light

intensity. Further research is hereby recommended for

the field application of the treatments on maize.

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