International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 4(1) pp. 1-11, January, 2013
Available online http://www.interesjournals.org/IRJPS
Copyright © 2013 International Research Journals
Full Length Research Paper
Growth performance of maize/cowpea in intercrop as
influenced by time of introducing cowpea and nitrogen
fertilizer
Amujoyegbe B.J.*1 and Elemo K.A.2
*1
Department of Crop Production and Protection, Faculty of Agriculture, Obafemi Awolowo University, Ile-Ife, Osun
State, Nigeria
2
Department of Plant Physiology and Crop Production, University of Agriculture, Abeokuta, Ogun State, Nigeria
Abstract
Field experiments on the growth performance of maize (Zea mays L.) and cowpea (Vigna unguiculata
(L.) Walps) in intercrop as influenced by time of introducing cowpea and nitrogen fertilizer applied to
maize was carried out at the Teaching and Research Farms of Obafemi Awolowo University (OAU), Ile0
0
Ife (latitude 7 28¹N and longitude 4 33¹E), located in rain forest agro-ecological zone and University of
0
0
Agriculture (UNAAB), Abeokuta (latitude 7 9¹N and longitude 3 21¹E) derived savanna zones of south
western Nigeria. The study was aimed at investigating the effects of time of introducing cowpea and
different levels of inorganic nitrogen applied to maize on the growth of maize and cowpea in
intercrop. Five dates of introducing cowpea into maize in intercrop (0, 14, 28, 42 and 56 days after
sowing maize (DASM), serving as main plot, were evaluated for intercropping cowpea alongside four
levels of nitrogen (0, 45, 90 and 135 kg N/ha), as subplot, in a split-plot design with three replications.
Maize (cv. DMRE-SRY) and cowpea (cv. Oloyin) were planted on flat in alternate double rows using
replacement series technique. Plant height, dry matter accumulation and relative growth rate were
determined for maize and cowpea at vegetative, flowering and physiological maturity. Data were
subjected to analysis of variance and where the F-test was significant, the treatment means were
separated using Duncan’s Multiple Range Test at p ≤ 0.05. Time of introducing cowpea had no effect
on growth attributes of maize at the two locations. However, delay in introducing cowpea beyond 14
DASM caused significant decrease in growth parameters of cowpea. Site locations, time of
introduction of cowpea affected growth of cowpea, while N fertilizer applied at 90 and 135 kg N/ha on
maize resulted led to increased growth of maize.
Keywords: Cowpea, Maize, Growth, Intercrop, Fertilizer, Dry Matter Accumulation.
INTRODUCITON
Maize (Zea mays L.) is the most widely grown cereal
crop in southwestern Nigeria and is one of the most
widely distributed of any other cereals (Obilana and
Fajemisin, 1977). In Africa, Nigeria produces about
5.1 metric tonnes out of the 26 million tonnes of maize
*Corresponding
Author
E-mail:
bamujo@oauife.edu.ng,bamujo2002@yahoo.com
produced annually (Food and Agriculture Organization
(FAO), 2003). About 50% of the green maize produced
in Nigeria comes from the southwestern Nigeria (Ikem
and Amusa, 2004). In south western Nigeria, planting is
done as soon as rain is stable, grown twice or thrice
within a year as intercrop with yam, cassava, ground nut
etc primarily as important staple food crop, livestock feed
and raw material and thus ameliorate hunger when other
food crops are hardly available. In this region, the
average yield is about 0.828 to 1.10 t/ha, well below the
2.7 t/ha in other developing world (Fakorede et al., 2001)
2 Int. Res. J. Plant Sci.
and it has grown to become local cash crop.
Cowpea is the most economically important grain
legume adapted to savanna ecologies where it matures
its grain on residual moisture. Nigeria and Niger account
for 87% of the world cowpea production (Ortiz, 1998;
(FAO), 2003). It is a crop that plays diverse role in
contributing to the food security, income generation and
soil amelioration for under small-scale farming
conditions. The grain contains about 25% protein and
64% carbohydrate and thus has high potential to reduce
malnutrition (Fatokun, 2002). The average grain yield of
cowpea generally ranges from 0.132 to 0.500 t/ha in the
dry savanna (FAO, 2003), where it is widely cultivated in
intercrop with sorghum, millet, and maize in northern
Nigeria
Growth and development of crops are highly
dependent on genetic composition and environmental
factors (Wallace et al., 1988; 1991) which enable the
crops to optimize the use of natural resources (Ofori and
Stern, 1987). Maize as cereal crop is highly dependent
on and responsive to high dosage of nitrogen fertilizer
while cowpea fixes nitrogen into the soil (Ogoke et al.,
2001), too much of which will impair its productivity
(Cardoso et al., 1993). Low soil fertility, especially of N
and P, is the prime factor limiting maize growth which
subsequently affects grain yield (Carsky and Iwuafor,
1999; FAO, 2000).
Despite the significant economic importance of
cowpea, its production is considered risky by many
growers in southwestern Nigeria where farmers desire to
incorporate it into the cropping system. Unlike maize
which is highly dependent and responsive to high
dosage of N fertilizer and performs well under good
moisture conditions, cowpea fixes nitrogen and is highly
sensitive to high moisture condition typically prevalent in
the southwestern Nigeria, because it enhances high
vegetative growth with negative effect on final yield
(Jackai and Adalla, 1997; Amusa and Adegbite, 2006).
Growth analysis is one approach to determine
factors that influence yield and plant development
(Happer, 1999). Analysing growth helps to monitor the
independent and interactive effects of various factors
affecting yield and opens the way to managing these
factors in integrated systems (Happer, 1999). A lot of
research is being carried out to determine the possibility
of producing cowpea in the southern agro-ecology of
Nigeria. Generally, literature is scanty on the effect of
time of introducing cowpea into maize cropping system
on growth of cowpea in southwestern Nigeria. Little
research carried out in the region on time of introducing
cowpea and N application of maize were done under
sole cropping and the main focus were on grain yield.
Hence the need to examine the growth performance of
component crops under different time of introducing
cowpea and N fertilizer levels applied to maize
in intercrop. The aim of this paper is to determine the
growth performance of maize and cowpea in intercrop as
affected by time of introducing cowpea and N fertilizer
applied to maize.
MATERIALS AND METHODS
The study was conducted for three years (2003 to 2005)
during the early and late seasons (March to July and
August to December respectively) at the Teaching and
Research Farm of the Obafemi Awolowo University
(OAU) Ile-Ife, Nigeria and the Teaching and Research
Farm, University of Agriculture, (UNAAB) Abeokuta.
Geographically, OAU is situated within the rain forest
0
0
zone, on latitude 7 28'N and longitude 4 33'E at an
elevation of about 200 m above sea level. It experiences
approximately eight months (March to October) of
bimodal rainfall. It has about four months (November –
February) of dry season each year with slight irregularity
in the rainfall distribution pattern. The mean yearly
rainfall for 2003 to 2005 were 1756.9, 1548.7 and 891.2
mm while that of Abeokuta in the respective years were
1436.9, 713 and 760.4 mm. With respect to
physicochemical properties, soils of the experimental
plots at OAU, Ile-Ife and UNAAB, Abeokuta were loamy
but acidic with pH of 5.63 to 5.71 at Ile-Ife and 5.42 to
5.61 at Abeokuta. The soil of the experimental plots at
UNAAB is coarse fine-grained granite and gneiss as
parent material (Aiboni, 2001), while those of OAU
belongs to Iwo series derived from coarse-grained
granite gneiss parent rock and classified as Ultisol (low
base status forest soils). It is well drained, grayish brown
to brownish red with predominantly high low acidity clay
– kaolinite (Harpstead, 1973). The organic matter
contents ranged from 1.78 to 2.18 % at Ile-Ife and 2.24
to 2.30 % at Abeokuta, the percentage total N at Ile-Ife
ranged from 0.17 to 0.18 and at Abeokuta, 0.12 to 0.13
all indicating low contents. The soil available P at Ile-Ife
was in the range of 3.21 to 3.38 ppm while at Abeokuta it
was 3.33 to 3.45 ppm. The exchangeable K was not high
as available P, ranging was 0.24 to 0.29 at Ile-Ife and
0.12 to 0.19 at Abeokuta.
One cowpea (cv. OLOYIN), brown seeded,
photoperiod neutral and maize (cv. DMR-ESR-Y), early
maturing yellow were used for the study. These two
varieties are the most widely grown popular in
southwestern Nigeria. The treatment consisted of five
times of introducing cowpea (0, 14, 28, 42 and 56 days
after sowing maize (DAS)) as the main plot and four
levels of N fertilizer (0, 45, 90 and 135 kg N/ha) in the
sub plot, applied as urea fertilizer to maize in two equal
split-applications at three weeks after planting and at
tasseling. The treatments were arranged in a split-plot
design with three replications. 26 kg P/ha was applied as
single super phosphate and 26 kg K/ha as murate
of potash basally applied by broadcasting before
Amujoyegbe and Elemo 3
harrowing. The seeds of cowpea and maize were treated
with 200g metalaxyl-M + 20g difenoconazole + 200g
thiamethoxam/kg shortly before planting to control soil
borne pests and pathogens. The main plot measured
33.8 m x 4 m while the sub-plot was 4 m x 7.2 m, to
contain four levels of nitrogen fertilizer. The maize and
cowpea were planted on flat in spatial alternate double
rows (2:2 ratio) using replacement series (Osiru and
Willey, 1972) with 0.90 m between rows. The maize
stands were maintained at 0.20 m within rows while the
cowpea was at 0.30 m. The net plot was made up of 3
to 6 which consisted two rows of maize and two rows of
cowpea at the centre of the plot. The guard rows were
rows 1 and 8 while rows 2 and 7 were used for
destructive sampling to determine growth parameters.
Data were collected at 3, 6 and 9 weeks after
planting (WAP) on the following growth parameters
which were determined on maize and cowpea: Plant
height and canopy height (cm) were measured from
ground level to the tip of the main stem of five randomly
tagged plants in the four middle rows, of each sub- plot
(Whigham, 1975). Dry matter determination, at each
sampling date, two randomly selected plants from rows 2
and 7 were harvested on sub-plot basis. The above
ground part was separated into leaves, stems and cob
(depending on the crop stage of development) and oven0
dried to a constant weight at 75 C for dry weight
determination. The total weights of the different parts of
each crop were divided to obtain average weights of the
plant parts used to calculate Relative Growth Rate
(RGR) according to (Leopold and Kriedemann, 1964;
Harper, 1999).
Data were subjected to analysis of variance
(ANOVA) to determine the effects of the treatments on
the parameters. Duncan’s Multiple Range Test (DMRT)
was used to separate means where F values were
significant at p ≤ 0.05. (Steele and Torrie, 1980; Gomez
and Gomez, 1984). All analyses were done with the
Statistical Analysis System (SAS) software version 8.1
(SAS, 1985).
RESULT AND DISCUSSION
The time of introducing cowpea had significant effect on
plant height of maize at 6 and 9 weeks after planting
(WAP) during the cropping years at Ile Ife and at
Abeokuta in 2004 and 2005 (Table 1). Maize in plots that
had cowpea introduced early (simultaneous sowing with
maize) and with little delay of 14 DASM were taller
compared with those that had cowpea sown at 42 days
after sowing maize (DASM). Average maize height
increased significantly with the presence of cowpea
coupled with different fertilizer rate. At the two locations,
nitrogen levels consistently increased the plant height
(PLH) of maize at 6 and 9 WAP. Significantly, taller
maize plants were observed with the application of 90
and 135 kg N/ha. The early introduction of cowpea may
have facilitated the fixation of N in the soil which is
mobile and highly required thus making it available for
the growth of the crop. This result corroborated the
findings of Eaglesham et al. (1981) who reported that
leguminous plants benefit intercropped cereals which
are planted in the same season due to N excretion and
nodules decomposition. The high significant effect of 90
and 135 kg N/ha on plant height may be expected
because maize grows better under high N levels
especially when the moisture is high (Adetunji, 1996;
Adegbite et al., 2002). The nitrogen that may be fixed by
the cowpea planted much later after maize had been
planted may not have any effect on the maize growth as
the maize might have overgrown the critical period of N
requirement which is usually the early growing period.
Also coupled with the poor growth of late sown cowpea,
the ability to fix nitrogen effectively may be very low.
The time of introducing cowpea had highly
significant effect (p ≤ 0.01) on canopy height and width
across years and locations (Table 2). Early introduction
of cowpea together with maize and subsequent delay of
cowpea till 14 DASM significantly led to high cowpea
canopy formation. The delay in introducing cowpea after
14 DASM caused significant decrease in cowpea canopy
and there was steady decrease in canopy development
as the delay in planting cowpea was prolonged until 56
DASM when the cowpea could not survive after seedling
emergence. The issue of interspecific competition
between well grown and established maize and the
young cowpea planted lately into the intercrop may not
be over-ruled. The maize, which has developed properly
with adequate canopy will strongly hinder effective
growth of any understorey crops that are not shadeloving like cowpea due to shade effect, water stress and
irradiation interception. Slight effects of N fertilizer on
cowpea canopy height at 9 weeks after planting (WAP)
at Ile-Ife and 6 WAP at Abeokuta were also noticeable.
The canopy formation increased slightly with increase in
fertilizer rate.
Dry matter accumulation (DMA) of maize as affected
by time of introducing cowpea, N fertilizer of maize in
intercrop and their interactions at Ile-Ife and Abeokuta
are shown in Table 3 while the DMA responses of
cowpea in intercrop are on Table 4. The DMA response
of maize to the treatments showed similar trend with
plant height regarding the effects of the rate of N
fertilizer applied. Application of 135 kg N/ha led
significantly to the highest DMA attained by maize at
each of the cropping years followed by application of 90
kg N/ha. However, the results of applying 135 and 90 kg
N/ha were not significantly different at Abeokuta The
significant effect of 45 kg N/ha over control on maize
height and DMA may be expected due to the fact that
the available nutrient in the soil may be beyond critical
4
Int. Res. J. Plant Sci.
Table 1. Plant height of maize (cv. DMR-ESR-Y) in intercrop with cowpea as affected by cowpea sowing date and N level on maize at Ile-Ife and Abeokuta in 2003-2005
-------------------------------------------------- Plant Height
+
(cm) ---------------------------------------------------------------
Ile-Ife
Treatment
Cowpea
sowing date
(after maize)
(D)
0
14
28
42
56
F-test
Nitrogen level
(N) (kg/ha)
0
45
90
135
F-test
Interaction
DxN
Abeokuta
2003
2004
6
(WAP)
9
65.5b
87.4a
82.4a
90.0a
91.4a
(WAP)
2005
2003
2004
2005
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
114.4c
120.5b
118.3bc
122.6b
132.4a
96.3a
85.2b
90.4ab
92.5a
93.5a
126.7a
104.2c
117.4b
119.7a
120.5a
98.2c
108.3b
120.3a
102.6b
90.3c
133.4a
134.7a
140.6a
135.2a
105.7b
128.3
123.4
125.4
129.0
130.3
137.2
138.3
135.4
133.7
130.4
108.7a
104.3ab
98.9b
90.9c
95.7d
**
**
**
**
**
*
ns
ns
111.5
121.8
112.1
112.8
ns
105.2c
100.5d
128.5b
136.5a
**
99.0b
80.4b
107.4ab
113.8a
**
121.5b
105.8c
127.8a
132.1a
**
100.5b
108.4b
128.4a
137.9a
**
130.5b
147.2b
186.5a
200.3a
**
120.2d
134.6c
148.7b
155.9a
**
ns
ns
ns
ns
ns
ns
ns
(WAP)
6
(WAP)
9 (WAP)
120.3b
122.5b
138.4a
109.4d
117.3c
78.8a
79.7a
75.2a
69.2b
70.3ab
136.3a
133.2a
125.3b
121.4b
120.3b
**
**
**
**
129.7c
135.4c
155.6b
163.3a
**
138.1c
124.4b
145.7b
152.9a
**
129.6c
138.3b
161.7a
163.3a
**
60.2c
75.2b
93.6a
94.5a
**
118.5c
127.5d
145.6b
150.0a
**
ns
ns
ns
ns
ns
+
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
** Significant at 1% level, ns Not significant, WAP weeks after planting
level needed by maize to survive in the intercrop.
The 45 kg N/ha applied may be adequate
to promote good growth and effective nodulation
(Miller, et al., 1982) especially among early
introduced cowpea.
The main effects of time of introducing cowpea
and N fertilizer levels on dry matter accumulation
of cowpea in intercrop across years at Ile-Ife and
Abeokuta as indicated in Table 4 showed similar
Amujoyegbe and Elemo 5
Table 2. Effect of cowpea sowing date and N fertilizer on canopy height of cowpea (cv. OLOYIN) in intercrop with cowpea at Ile-Ife and Abeokuta in 2003 to 2005 late seasons
----------------------------------------------------------Treatment
Canopy height (cm) -----------------------------------------------
Ile-Ife
Abeokuta
2003
Cowpea sowing date
(after maize) (D)
0
14
28
42
56
F-test
Nitrogen
(kg/ha)
0
+
level
2004
2005
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
27.27b
31.32a
32.00a
26.50b
38.25a
36.00a
34.00a
30.00b
32.23a
38.25a
28.25b
26.55b
43.21a
46.36a
41.98a
34.26b
27.25b
23.00c
19.22c
**
**
28.52
(WAP)
2003
2004
2005
9
(WAP)
6 (WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
32.00a
31.32a
27.36b
25.50b
36.54a
35.80a
33.00a
27.03b
28.08a
30.20a
27.70a
25.60a
35.03a
34.99a
34.87a
31.52a
36.25a
36.85a
26.59b
26.22b
45.28a
43.68a
38.21a
35.02b
30.30a
29.43a
22.77b
19.26b
34.75a
32.50a
26.87a
20.52b
23.24c
25.25b
22.50c
10.20b
6.32b
20.23b
30.33b
08.22c
10.11c
**
**
**
**
**
**
**
**
**
**
(N)
45
90
29.33
29.68
35.33
34.82
36.34
28.59
29.32
29.87
42.36b
42.86b
43.51a
30.42
30.38
28.89
37.33b
38.05ab
38.56a
26.31
28.22
28.52
32.33
32.48
34.21
34.65b
34.53b
36.44a
40.32
41.18
40.16
25.28c
27.22b
27.43b
30.21
33.28
31.45
135
F-test
30.54
35.48
30.54
43.87a
30.21
39.05a
29.36
35.69
37.32a
42.22
30.31a
31.87
ns
ns
ns
*
ns
*
ns
ns
*
ns
*
ns
ns
ns
ns
ns
ns
ns
ns
ns
Ns
ns
ns
ns
Interaction
DxN
+
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
**, * Significant at 1and 5 % levels, ns Not significant, WAP weeks after planting
trend with canopy height. The delay in introduction
cowpea into established maize plots significantly
increased the dry matter accumulation of cowpea
across the sampling periods irrespective of the
cropping years. Simultaneous sowing and delay in
sowing cowpea by 14 DASM significantly caused
6 Int. Res. J. Plant Sci.
Table 3. Effect of cowpea sowing date and N fertilizer on dry matter accumulation of maize (cv. DMR-ESR-Y) in intercrop with cowpea at Ile-Ife and Abeokuta in 2003 to 2005
late seasons
+
-------------------------------------------------- Dry Matter Accumulation (g/plant)----------------------------------------------Ile-Ife
Treatment
Abeokuta
2003
2004
2005
2003
2004
2005
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
Cowpea
sowing date
(after maize)
(D)
0
4.11
16.53
3.04
16.48
2.91
8.70
5.42
10.22
2.72
10.58
3.22
6.73
14
4.23
16.03
3.08
15.39
2.82
7.91
11.35
2.76
10.07
3.58
6.54
28
4.38
16.48
3.09
16.49
2.99
7.65
5.31
5.09
10.89
3.81
11.52
3.00
5.22
42
5.05
16.40
2.59
16.39
2.86
7.84
4.78
11.54
3.90
10.48
2.73
5.87
56
F-test
4.77
15.82
2.64
16.40
2.88
7.78
4.95
11.09
3.95
10.55
2.85
5.73
ns
ns
ns
ns
ns
ns
ns
ns
Ns
ns
ns
ns
Nitrogen
level
(N)
(kg/ha)
0
45
90
135
F-test
6.50
6.66
7.61
7.65
10.4c
12.19b
12.82b
13.85a
2.53b
2.22b
3.51a
4.65a
9.89b
15.21a
17.89a
19.50a
3.03b
3.14b
3.77b
5.39a
3.99b
4.69b
6.76a
7.70a
2.55
3.17
5.46
5.10
6.55b
8.35b
11.93a
11.79a
2.38b
2.73b
5.00a
5.18a
7.32b
7.93b
10.54a
11.37a
1.72c
2.34b
3.21a
3.37a
4.73c
6.25b
7.06a
7.83a
ns
**
**
**
**
**
ns
**
**
**
**
**
Interaction
DxN
ns
ns
ns
ns
ns
ns
ns
ns
Ns
ns
ns
ns
+
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
** Significant at 1% level, ns Not significant, WAP weeks after planting
higher DMA of cowpea, further delay after 28
DASM led to significant decrease in DMA which
further led to the cowpea crops not reaching
maturity with stunted growth in 2003 at Ile-Ife and
not reaching flowering stage at Abeokuta in 2003
and 2005.
Nitrogen fertilizer levels significantly contributed to
increasing the DMA of cowpea at the two locations
irrespective of the cropping years.
Amujoyegbe and Elemo 7
Table 4. Effect of cowpea sowing date and N fertilizer on dry matter accumulation of cowpea (cv. OLOYIN) in intercrop with cowpea at Ile-Ife and Abeokuta in 2003 to 2005 late
seasons
+
----------------------------------------------- Dry Matter Accumulation (g/plant)-------------------------------------------Treatment
Ile-Ife
Abeokuta
2003
Cowpea sowing date
(after maize) (D)
0
14
28
42
56
F-test
Nitrogen
(kg/ha)
0
45
90
135
F-test
Interaction
DxN
level
2004
2005
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
19.9a
15.4b
71.73b
117.79a
23.52a
21.84a
82.17a
85.01a
5.24a
6.52a
14.0b
7.99c
0.00d
64.06b
48.02c
0.00d
18.95b
6.61c
4.21c
66.54b
45.19c
18.92d
**
**
**
13.33b
14.21b
18.730a
58.18b
67.56ab
67.77ab
77.85a
20.00b
20.15b
24.07a
26.33a
2003
9
(WAP)
2004
2005
6 (WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
34.98a
36.05a
47.30a
17.66b
97.6a
52.5b
12.22a
11.09a
97.21a
39.48b
12.85b
14.27a
55.21a
43.13b
4.12b
1.95c
1.35c
26.14b
20.34bc
18.32c
16.80b
14.79b
0.00c
39.3c
38.6c
0.01d
8.82b
2.78c
2.21c
21.38c
18.69c
10.54d
10.61b
12.49b
0.00c
25.24c
24.86c
0.00d
**
**
**
**
**
**
**
**
**
55.32c
60.55b
72.4ab
16.24b
17.51b
21.46a
20.08c
20.44c
25.22b
60.46c
70.25b
73.42b
12.32b
12.80b
19.44a
25.33a
58.57c
65.22b
67.31ab
73.2a
13.45b
13.27b
15.00a
80.24a
43.60c
57.62b
67.05b
97.92a
**
15.36a
**
95.28a
**
20.28a
**
54.1b
60.17ab
63.2a
67.8a
ns
ns
ns
ns
(N)
20.52a
*
*
**
**
**
**
34.32a
**
ns
ns
ns
ns
ns
ns
ns
**
ns
+
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
**, * Significant at 1and 5 % levels, ns Not significant, WAP weeks after planting
Application of 135 kg N/ha significantly increased
the DMA of cowpea at both locations followed by
the application of 90 kg N/ha while the effects of
control plots were the least.
Unlike the effects of time of introducing
cowpea and N fertilizer levels on maize height and
DMA, the effect of treatments on relative growth
rate (RGR) of maize at Ile-Ife and Abeokuta
differed as shown in Table 5. The relative growth
8 Int. Res. J. Plant Sci.
Table 5. Effect of cowpea sowing date and N fertilizer on relative growth rate of maize (cv. DMR-ESR-Y) in intercrop with cowpea at Ile-Ife and Abeokuta in 2003 to 2005 late seasons
+
-------------------------------------------------(Relative Growth Rate (g g-1 week-1)---------------------------------------------Treatment
Ile-Ife
Abeokuta
2003
6
Cowpea sowing date
(after maize) (D)
0
2005
2003
2004
2005
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6 (WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
14
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
28
42
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
0.02
0.02
0.01
0.01
56
F-test
Nitrogen level
(kg/ha)
0
45
90
135
F-test
Interaction
0.02
ns
0.01
ns
0.02
ns
0.01
ns
0.02
Ns
0.01
ns
0.02
ns
0.01
ns
0.02
ns
0.01
ns
0.02
ns
0.01
ns
0.03
0.03
0.03
0.03
ns
0.01
0.01
0.01
0.01
ns
0.01b
0.01b
0.02a
0.02a
**
0.01
0.01
0.01
0.01
ns
0.02b
0.02b
0.03a
0.03a
*
0.01b
0.01b
0.02a
0.02a
**
0.02
0.02
0.02
0.02
ns
0.01
0.01
0.01
0.01
ns
0.02
0.02
0.02
0.03
**
0.01
0.01
0.01
0.01
ns
0.02
0.02
0.02
0.02
ns
0.06
0.06
0.07
0.07
ns
ns
ns
ns
ns
Ns
ns
ns
ns
ns
ns
ns
ns
DxN
+
(WAP)
2004
(N)
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
**, * Significant at 1and 5 % levels, ns Not significant, WAP weeks after planting
rate of maize was significantly increased by N
fertilizer levels applied at 6 and 9 WAP at Ile-Ife in
2004 and 2005 respectively and at Abeokuta
at 6 WAP in 2004 only. There were no significant
differences on different rates of N including the
control on RGR of maize at the two locations. The
observed slight effects of N on RGR of maize
at Ile-Ife may be due to high rainfall which may
favour easy availability of soil nutrient for higher
biomass production. Adetiloye, (2001) reported
similar result and emphasized the need
for adequate soil moisture for the growth and
Amujoyegbe and Elemo 9
Table 6. Effect of cowpea sowing date and N fertilizer on relative growth rate of cowpea (cv. OLOYIN) in intercrop with cowpea at Ile-Ife and Abeokuta in 2003 to 2005 late seasons
+
-------------------------------------------------(Relative Growth Rate (g g-1 week-1)---------------------------------------------Ile-Ife
Treatment
Cowpea sowing date
(after maize) (D)
0
14
28
42
56
F-test
Nitrogen
(kg/ha)
0
45
90
135
F-test
Interaction
DxN
Abeokuta
2003
level
2004
2005
2003
2004
2005
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
6
(WAP)
9
(WAP)
0.11a
0.10a
0.10
0.06
0.04
0.09
0.12a
0.05
0.05
0.09
0.06
0.07
0.05bc
0.03bc
0.06b
0.01c
**
0.09a
0.07b
0.07b
0.01c
**
0.09
0.09
0.09
0.07
ns
0.06
0.06
0.01
0.07
ns
0.07
0.06
0.06
0.05
Ns
0.08
0.08
0.02
0.02
ns
0.08b
0.06c
0.08b
0.00d
**
0.05
0.04
0.03
0.00
**
0.05
0.06
0.08
0.07
ns
0.06
0.06
0.05
0.04
ns
0.04
0.08
0.04
0.00
ns
0.05
0.05
0.03
0.00
ns
0.03b
0.02b
0.08a
0.09a
**
0.07
0.07
0.06
0.06
ns
0.10
0.10
0.11
0.11
ns
0.04b
0.05a
0.05a
0.05a
*
0.09c
0.10b
0.11a
0.12b
*
0.04
0.05
0.05
0.06
ns
0.09
0.09
0.09
0.10
ns
0.05
0.05
0.03
0.04
ns
0.08
0.08
0.09
0.09
ns
0.08
0.08
0.08
0.09
ns
0.08
0.06
0.08
0.08
ns
0.07
0.07
0.06
0.06
ns
ns
ns
ns
ns
Ns
ns
ns
ns
ns
ns
ns
ns
(N)
+
In a column, means followed by the same letters are not significantly different at 5% levels of probability using DMRT
**, * Significant at 1and 5 % levels, ns Not significant, WAP weeks after planting
development of maize even in the presence of
available soil nutrient.
Table 6 shows the effects of time of
introducing cowpea and N fertilizer levels on the
relative growth rate (RGR) of cowpea at Ile-Ife and
Abeokuta during 2003-2005 late growing season.
Time of introducing cowpea had highly significant
effect on the RGR of cowpea at Ile-Ife and
Abeokuta in 2003. High RGR were observed at
simultaneous planting of cowpea and maize,
however, further delay significantly reduced
RGR until 56 DASM when growth of cowpea was
10 Int. Res. J. Plant Sci.
extremely retarded. Significant effect of Nitrogen fertilizer
was noticed to significantly increased RGR of cowpea at
6 WAP in Ile-Ife with the application of 90 kg N/ha and
above.
SUMMARY AND CONCLUSIONS
The paper investigated the effect of time of introducing
cowpea and nitrogen fertilizer on growth performance of
maize (cv. DMR-ESR-Y) and cowpea (cv. OLOYIN) in
intercrop at a derived savanna location (Abeokuta) and a
rain forest location (Ile-Ife) in southwestern Nigeria.
Results showed that early planting of cowpea into maize
plot significantly enhanced maize growth coupled with
the application of at least 90 kg N/ha. Average plant
height, dry matter accumulation and relative growth rate
of maize increased significantly with increase in the rate
of N fertilizer. Application of 90 and 135 kg N/ha
significantly increased the growth parameters of maize
at 6 WAP, one week to silking and enabled the
component crops to attain optimum growth as it did not
show any detrimental effect on cowpea.
Early introduction of cowpea into the established
maize plot was observed to significantly increased
canopy formation, dry matter accumulation and relative
growth rate of cowpea planted at the two locations and
three cropping years. Introducing cowpea into maize plot
should not be delayed beyond 14DASM to obtain
optimum growth of cowpea which may have significant
development on nitrogen fixation and subsequent yield
of the component crops in intercrop. Late planting of
cowpea led to severe interspecific competition with
maize due to water stress and solar irradiation
interception caused by shading effect from the well
established maize.
REFERENCES
Adegbite LO, H Tijani-Eniola, AA Adegbite, PO Oyekan, TA Fadare
(2002). Determination of optimum planting date and approximate
planting pattern in a maize-soybean intercrop. Moor J. Agric. Res.
3:41-49
Adetiloye PO (2001). The effect of maize population and nitrogen level
on the performance of maize/cowpea intercrop ASSET Series A Vol.
1 (1): 115-120
Adetunji MT (1996). Nitrogen utilization by maize in a maize-cowpea
sequential cropping of an intensively cultivated tropical ultisol. J.
India Society of Soil Sci. 44 (1): 85-88
Aiboni VU (2001). Characteristics and classification of soils of a
representative topographyic locations in the University of
Agriculture, Abeokuta. ASSET Series A Vol. 1 (1): 51-62
Amusa NA, AA Adegbite (2006). The Major Economic Field Diseases
of Cowpea in the Humid Agro-Ecologies of South-Western Nigeria
World Applied Science Journal, 1 (1): 12-18.
Cardoso MJ, FR Freire Filho, VQ Ribeiro, AB Frota, Melo F deB
(1993). Plant density of maize-cowpea intercrops under irrigation.
Pesquisa Agropecuaria Brasileira. 28:93-99.
Carsky RJ, Iwuafor ENO (1999). Contribution of soil fertility research
and maintenance to improved maize production in sub-saharan
Africa. Pp 3-22 in Badu-Apraku B, Fakorede M.A.B., Ouedraogo M and
Quin F.M. (eds). Strategy for Sustainable Maize Production in West
and Central Africa Proceedings of a Regional Maize Workshop held
in Cotonou, Benin Republic 21 to 25 April 1997.IITA-Cotonou.
Eaglesham ARJ, A Ayanaba, RV Ranga, DL Eskew (1981). Improving
the nitrogen nutrition of maize by intercropping with cowpea. Soil
Biology and Biochemistry. 13:169-171
Fakorede MAB, B Badu-Apraku, O Coulibaly, Fajemisin JM (2001).
Maize research and development priorities in sub-Saharan Africa in
the next millennium. In Badu-Apraku, B., M.A.B. Fakorede, O.
Coulibaly and R.J.Carskey (eds) Impact, challenges and prospects
of maize research and development in West and Central Africa.
Proceedings of a Regional Maize Workshop, IITA-Cotonou, Benin
Republic, 4-7 May,1999. WECAMAN/IITA. pp 31-58
FAO (2003). The state of food insecurity in the world (FAOSTAT
website) 8 pp.
Fatokun CA (2002). Breeding cowpea for resistance to insect pest:
attempted crosses between cowpea and Vigna vexillata. In C.A.
Fatokun, S.A. Tarawali, B.B. Singh, P.M. Kormawa, and M. Tamo
(eds0 Challenges and opportunities for enhancing sustainable
cowpea production. Proceedings of the World Conference III held at
the IITA, Ibadan, Nigeria, 4-8 September 2000, IITA, Ibadan Nigeria
pp 52-61
Food and Agriculture Organization (FAO) (2000). Production Year
Book Vol 54
Gomez KA, Gomez AA (1984). Statistical procedure for agricultural
research. 2nd.Edition, John Wiley & Sons Co N.Y. 680 pp.
Harper F (1999). Principles of arable crop production. Blackwell
Science USA 333pp
Harpstead M (1973). A classification of some Nigerian soils. Soil Sci.
116: 437-443
Ikem JE, Amusa NA (2004). Maize research and production in Nigeria.
African Journal of Biotechnology. Vol 3(6):302-307
Jackai LEW, Adalla CB (1997). Pest management practices in cowpea.
Pp 240-258 in Singh, B.B., D.R. Mohan Raj, K.E. Dashiell, and
L.E.N. Jackai (eds). Advances in Cowpea Research. Co-publication
of IITA and Japan International research Centre for Agricultural
Sciences (JIRCAS).
Jackai LEW, Adalla CB (1997). Pest management practices in cowpea
: a review page 240-258. In K.E Dasheiell and L.E.N. Jackai. IITA,
Ibadan and Japan Inter-Research Centre for Agric science.
(JIRCAS)
Leopold AC, PE Kriedemann (1975). Plant growth and development.
McGraw-Hil, Inc.545pp
Miller JC, Scot SS, Zary KW, O’ttair SR (1982). Influence of available
nitrate levels on N fixation in three cultivars of cowpea Agronomy
Journal 74 (1) 14-18.
Obilana AT, Fajemisin JM (1977). Methodology of improving maize
varieties (Zea mays L.) in Nigeria. Paper presented at the 3rd
National Seed Improvement Course, August 15 – September 16,
1977. Moor Plantation, Ibadan. Pp 17-27
Ofori F, WR Stern (1986). Maize/cowpea intercrop: effect of nitrogen
fertilizer on productivity and efficiency. Field Crops Research 14:
247-26.
Ogoke IJ, RJ Carsky, AO Togun, K Dashiel (2001). Maize yield
following phosphorus- fertilized soybean in the Nigeria Guinea
savanna Pp 205-213 In Badu-Apraku, B., M.A.B. Fakorede, O.
Coulibaly and R. J. Carsky (eds) Impact, challenges and prospects
of maize research and development in West and Central Africa.
Proceedings of a Regional Maize Workshop, IITA-Cotonou, Benin
Republic, 4-7 May, 1999. WECAMAN/IITA.
Ortiz R (1998). Cowpea from Nigeria, a silent food revolution. Outlook
on Agriculture. 27(2): 125-12
Osiru DOS, Willey RW (1972). Studies on mixture of dwarf sorghum
and beans with particular references to plant population. J. Agric
Sci. Cambridge 79: 531- 540
Salisbury FB, Ross C (1994). Plant physiology. Second ed. Wadsworth
Publishing Comp, Inc. Belmont, California. Pp 436
SAS Institute, 1985. SAS user’s guide. Statistics version 5th Ed. SAS
Institute, Cory, NC, U.S.A.
Amujoyegbe and Elemo 11
Steel SGD, Torrie JH (1980). Principles and procedure of statistics. A
biometrical approach. McGraw-Hill Book Co. Inc. London.663pp
Wallace DH, Baudoin JP, Beaver JS, Coyne DP, Halseth DE, Masaya
PN, Munger HM, Myers JR, Silbernagel M, Yourstone KS, RW Zobel
(1991). Improving efficiency of breeding for higher crop yield.
Theoretical Applied Genetics. USA. 105: 583-591
Wallace DH, DE Halseth, PN Masaya, KS Yourstone, RW Zobel
(1988). Using yield trials to analys e the physiological genetics of
yield accumulation and the genotype x environmental interaction
effect of yield. Ann. Rep. Bean Improv. Coop. USA. 30: vii-xxiv
Wallace DH, Masaya PN (1988). Using yield trial data to analyze the
physiological genetics of yield accumulation and the genotype x
environmental interaction effects on yield. Annual report on Bean
Improvement Coorporation .USA 30: vii-xxiv
Whigham DK (1975). International soybean variety experiment. First
report of results University of Illinois, Urbana-Champaign, INTSDY
series No 8 ppxi