Vol.2, No.2, 125-130 (2011) Agricultural Sci ences
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
Water use efficiencies o f maiz e cultivars grown
under rain-fed conditions
Daniel Kwasi Asare*, Ju stice Okona Frimpong , Emmanuel Ofori A yeh, Harry Mensah Amoatey
Department of Plant and Soil Sciences, Biotechnology and Nuclear Agriculture Research Institute, Ghana Atomic Energy Commis-
sion, Legon-Accra, Ghana; *Corresponding Author: daniel_asare@yahoo.com
Received 10 February 2011; revised 10 March 2011; accepted 28 March 2011.
Enhancing water use efficiencies of rain-fed
maize is a requirement for sustainable maize
production, particularly in areas prone to low/
drought and errat ic rainfall patterns. This study
was conducted to assess the relationship be-
tween total biomass/grain yield and water use
efficiencies of three maize cultivars (Golden
Crystal, Mamaba and Obatanpa) grown under
rain-fed conditions in a coastal savannah agro-
ecological environment of Ghana. Results of
the study showed that a unified linear model,
WUETDM = 0.03 TDM with R2 = 0.765 and P
0.001, described adequately the relation be-
tween water use efficiency and total biomass
(dry matter), which is applicable for the three
maize cultivars for both the major and minor
cropping seasons. A linear model could only,
however, describe adequately well the relation
between WUEGY and GY for the major (WUEGY =
0.001 GY0.67; R2 = 0. 996; P ≤ 0.001) and minor
(WUEGY = 0. 002 GY + 0.289; R2 = 0.992; P ≤ 0.001)
cropping seasons for all the maize cultivars.
The linear models developed for the maize cul-
tivars, relating WUEGY to GY, are specific to
each of the crop growing seasons, indicating
that seasonal rainfall impacts significantly on
harvest index of the maize cultivars but diffe-
rently in each of the crop growing seasons as a
results of differences in seasonal rainfall. How-
ever, the models could be used to estimate wa-
ter use efficiencies of each of the three maize
cultivars given the appropriate TDM and GY as
inputs for the environment under which the
study was conducted.
Keywords: Water Use Efficiency; Maize Cultivars;
Maize (Zea mays L.) is grown over a wide range of
climatic conditions, differing in distribution and quantity
of seasonal rainfall. Besides, the crop is grown under irri-
gated and rain-fed conditions. Rain-fed maize production
forms about 75% of agriculture in areas where the crop is
the main sourc e of food a nd i ncom e for t he peopl e [1] .
Though maize thrives best on soils having adequate
moisture during the growing season, the crop tolerates
dry periods, especially during the first three to four
weeks of growth. In areas such as the semi-arid and dry
sub-humid environments, including the coastal savannah
environment, the amount of rainfall is not only the li-
miting factor of rain-fed maize production but also the
erratic nature of rainfall [2,3]. However, water stress
occurring at different crop developmental stages could
potentially limit biomass accumulation and consequently
reduce grain yield of the maize crop. The extent of re-
duction in maize productivity depends not only on the
severity of the water stress or drought but also on the
stage of the crop development [4,5], the crop tolerance
to water stress/drought and the efficiency with which the
maize crop uses available soil water for growth, biomass
accumulation and yield production.
Water use efficiency of rain-fed maize has been stu-
died by several workers including Frimpong et al. [6]
and Tijani et al. [7]. These studies are important for
identifying maize cultivar s that are efficient in the use of
limited soil water for biomass and grain yield production.
Identified maize cultivars, when adopted by farmers,
could assist in enhancing sustainable maize production
in areas where rain-fed agriculture is mostly practiced,
particularly in areas that experience low and erratic
rainfall. Additionally, with the potential impact of cli-
mate change on agriculture as a result of reduced and
erratic rainfall in some regions, it has become more im-
perative to breed or select crops that could use effec-
tively and efficiently low and scarce soil water without
drastically constraining crop production in areas that
D. K. Asare et al. / Agricultural Sciences 2 (2011) 125-130
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
depend mostly on rain-fed agriculture, and thereby sus-
taining crop production and alleviating poverty among
resource-poor farmers.
The relationships between grain yield and water use
by maize have received attention from several workers.
These relationships have been found to be either linear
(Adamtey et al. [8], Oktem et al. [9], Yazar et al. [10],
Istanbulluoglu et al. [11] and Irmark et al. [12]) o r cu rv i-
linear (Cetin and Bilgel [13] and Yazar et al. [10]). Si-
milarly, Grassini et al. [14] and Abbas et al. [15] ob-
served a linear relationship between water use efficiency
and biomass under irrigated conditions. Our study,
therefore, evaluates the relationship between water use
efficiencies and biomass/grain yields of three maize cul-
tivars grown under rain-fed conditions in a coastal sa-
vannah environment of Ghana.
Field experiments were conducted during the 2008
year under both the major and minor cropping seasons
(Frimpong et al. [6]). Specifically, experiments were
established at the research farm of the Biotechnology
and Nuclear Agriculture Research Institute of the Ghana
Atomic Energy Commission, Kwabenya-Atomic (Ghana).
The site lies on latitude 05°40' N and longitude 0°13' W,
elevated at 76 m above sea level. The study area is lo-
cated in the coastal savannah environment of Ghana and
receives an annual rainfall that ranges between 700 mm
and 1000 mm. The soil at the site is the Haatso series, a
well-drained savannah ochrosol described as Ferric
Acrisol, (FAO/UNESCO, [16]), derived from quartzite
schist. Some of the chemical and physical characteristics
of some of the soil are presented in Table 1. The µMETOS®,
a micro electronic weather station (Pessl Instruments
GmbH, Weiz, Austria) located about 50 m from the ex-
perimental plots recorded daily weather variables in-
cluding precipitation.
Maize cultivars used for the experiments were Golden
Crystal, Mamaba and Obatanpa which were bred for
high grain yield and improved nutritional status [17,18].
The maize cultivar Mamaba is a three-way hybrid quali-
ty protein maize [19] while Golden Crystal and Ob-
atanpa are normal open pollinated maize [17]. Of these
maize cultivars, Obatanpa has been widely adopted by
farmers, covering more than 50% of maize acreage in
Ghana and other parts of West Africa [20,21].
Seeds of the maize cultivars were sown on April 28,
2008 and September 01 2008 for the major and minor
cropping season, respectively. Seeding was done at a
distance of 0.4 m within rows and 0.8 m between rows.
Seedlings were thinned to 2 plants per hill one week
after germination to obtain 78,750 plants·ha–1. A total of
275.0 kg·ha–1 of 15:15:15 NPK fertilizer was split-ap-
plied by broadcasting two weeks and four weeks after
germination [17]. Weeds were controlled mechanically
by hoeing whenever necessary. A 100 mL broad spec-
trum insecticide, Pyrinex 48 EC (O, O-Diethyl 0-3, 5,
6-trichloro-2-pyridylphosphorothionate) in 100 L of wa-
ter was split-applied five and seven weeks after crop
establishment during the major and minor cropping sea-
sons. The experimental design used was the randomized
complete block design in four replicates with the three
maize cultivars as treatments. Each sub-plot measured
10.0 m by 10.0 m.
Access tubes were installed in each of the sub -plots to
120 cm soil depth before 50% seed germination. The
tubes were installed in between two central rows within
each sub-plot to facilitate in situ moisture monitoring at
20 cm stepwise in a 120 cm soil profile with the CPN
(Campbell Pacific Nuclear) 503DR Hydro (neutron)
probe at a two-week interval throughout the entire maize
growing seasons.
Eight maize plants were sampled at 28, 42, 56, 70, 84
and 98 days after emergence (DAE) from an area of 1.28
m2 in each sub-plot. Plant samples were separated into
leaves, stem, ear, cob, husk and grain components. Sub-
samples of fresh plant components were oven-dried at
70˚C until constant weights for total dry matter deter mi-
nation. Additionally, grain yield at crop maturity was
taken from a 10.5 m2 area on August 8, 2008 and De-
cember 10, 2008 for the major and minor cropping sea-
son, respectively. Grain yield was determined at grain
moisture content that ranged betwee n 13.0% and 1 5.0%.
Actual evapotranspitation (AET) for the maize culti-
vars was estimated from seed emergence to crop maturi-
ty using the water balance model of the root zone [22]:
Table 1. Some of the chemical and physical properties of the soil at the experimental site (Frimpong et al., 2011).
Soil Layer (cm) pH (H2O)
(1:2) Org. C
(%) Total N
(%) Avail. P
(mg·kg–1) K
(cmol + kg–1) Sand
(%) Silt
(%) Clay
(%) Bulk density
20-40 7.39 0.50 0.34 6.79 0.30 40.4 44.7 14.9 1.22
80-100 7.79 0.36 0.42 2.40 0.21 46.3 43.0 10.7 1.47
100-120 7.85 0.23 1.13 2.10 0.22 55.8 36.4 7.8 1.38
D. K. Asare et al. / Agricultural Sciences 2 (2011) 125-130 127
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
ΔS = P + I R D – AET (1)
where P is precipitation (mm), I is irrigation (mm), AET
is actual evapotranspiration (mm) R is run-off (mm), D
is drainage or capillary rise (mm) and ΔS is the change in
stored soil moisture in the root zone (mm).
Irrigation (I) was set to zero as the experiments were
conducted under rain-fed conditions. Run-off was also
set to zero because the slope of the land is less than 1%.
Drainage or capillary rise (D) below the root zone (100
cm below the soil surface) was estimated based on the
Darcy’s water flux model integrated over the measuring
time interval:
−= )(
where K(θ) is the hydraulic conductivity (mm·d–1) cor-
responding to the soil moisture content (θ), ΔH is the
change in hydraulic head (mm) which is made up of the
change in matric potential (Ψm) and change in gravi-
metric potential (Ψg), Δz (mm) is the difference be-
tween the two soil depths at which Ψm and Ψg were
estimated for ΔH computation and Δt (d) is the mea-
suring time interval. The hydraulic conductivity and
matric potential were estimated using the pedo-transfer
functions given by Campbell [23] with soil particle
fractions as inputs.
The water use efficiency (kg·ha–1·mm–1) of the maize
cultivars was estimated in terms of total above ground
biomass (WUETDM):
(3 )
and in terms of grain yield (WUE GY):
where CTDM and GY ar e cumulative total above groun d
biomass (kg·ha–1) and grain yield (kg·ha–1), respectively,
and CAET is the cumulative actual evapotranspiration
Water use efficiency was regressed against total bio-
mass and grain yield for each of the maize cultivars for
the major and minor cropping seasons. Additionally,
biomass and water use efficiency data were pooled to-
gether and then regressed to assess the possibility of
establishing a unified regression equation relating water
use efficiency and total biomass or grain yield applica-
tion for all the rain-fed conditions (major and minor
cropping sea son s).
Weather conditions were different during the major
and minor cropping seasons. Generally, the mean maxi-
mum and minimum temperatures were 30.5˚C and
23.5˚C, respectively, mean relative humidity was 81.4%,
mean solar radiation was 212.1 W·m–2 and seasonal
rainfall was 502.4 mm during the major cropping season.
For the minor cropping season, however, the mean
maximum and minimum air temperatures were 31.9˚C
and 23.6˚C, respectively, mean relative humidity was
78.2%, the mean solar radiation was 229.7 W·m–2 while
the seasonal rainfall was 290.7 mm [6].
Soil water use efficiency is an important crop index
used to assess how soil water is used efficiently for total
biomass and grain yield production [24]. Generally, the
maize cultivars had similar WUE that increased from
seed emergence and peaked on 84 DAE at about 18.0
kg·ha–1·mm–1 before declining to about 6.0 kg·ha–1·mm–1
on 98 DAE during the major cropping season. A similar
trend was observed for the minor cropping season, how-
ever, the maize cultivar Obatanpa had the highest WUE
for biomass production of about 32.0 kg·ha–1·mm–1 on 56
DAE and all the maize cultivars had similar WUETDM
values of about 28.0 kg·ha–1·mm–1 on 70 DAE before
declining to about 10.0 kg ha–1·mm–1 on 98 DAE during
the minor cropping season. Generally, the seasonal
WUETDM for the maize cultivars for the major cropping
season were comparable to the val ue of 8.0 kg·ha–1·mm–1
reported by Mox et al. [25] for rain-fed maize in eastern
Zambia while WUE TDM for the maize cultivars during the
minor cropping season was higher than values reported
by Mox et al. [25] but l fell below the range 16.5-21.5
kg·ha–1·mm–1 reported by Dagdelin et al. [26]. The com-
paratively higher season WUETDM for the maize cultivars
during the minor season compared to values for the major
season was due to higher biomass accumulated at rela-
tively lower seasona l evapot r a ns piration [ 6].
For WUEGY, the maize cultivar Mamaba had signifi-
cantly the highest value of about 13.0 kg·ha–1·mm–1 (P
0.05) during the major cropping season compared to val-
ues for the other two maize cultivars. However, WUE GY
for the maize cultivars during the minor cropping season
were statistically similar and ranged from 19.0
kg·ha–1·mm–1 for Obatanpa, 15.4 kg·ha–1·mm–1 for Ma-
maba to 14.6 kg·ha–1·mm–1 for Golden Crystal. Similar
WUEGY values ranging from 11.0 kg·ha–1·mm–1 to 18.0
kg·ha–1·mm–1, 9.3 kg·ha–1·mm–1 to 13.8 kg·ha–1·mm–1 and
11.4 kg·ha–1·mm–1 to 14.4 kg·ha–1·mm–1 have been re-
ported by Tijani et al. [7], El-Tantawy et al. [27] and
Meena et al. [28], respectively, for maize grown under
rain-fed condit ions .
Linearly regressing WUET DM against TDM for each of
the maize cultivars resulted in a good linear model with
R2 values that ranged between 0.890 and 0.928 for the
major cropping season (Table 2). Similar results were
obtained for the minor cropping season except that R2
values range d bet wee n 0.756 and 0. 864 (Table 2).
128 D. K. Asare et al. / Agricultural Sciences 2 (2011) 125-130
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
Table 2. Relationship between water use efficiency (WUETDM) and total dry biomass (TDM) for three maize cultivars
during the major and minor cropping seasons and for the combined seasons.
Season (s) Maize
Cultivar (s) Regression model Correlation
Coefficient (R2) P-value
Major Golden Crystal WUETDM = 0.002 × TDM + 1.26 0.890 ≤ 0.001**
Major Mama b a WUETDM = 0.002 × TDM + 1.02 0.918 ≤ 0.001**
Major Obatanpa WUETDM = 0.002 × TDM + 1.09 0.928 ≤ 0.001**
Minor Golden Crystal WUETDM = 0.003 × TDM + 3.19 0.864 ≤ 0.001**
Minor Mamab a WUETDM = 0.002 × TDM + 2.85 0.845 ≤ 0.001**
Minor Obatanpa WUETDM = 0.003 × TDM + 5.86 0.756 ≤ 0.002**
Major + Minor Golden Crystal WUETDM = 0.003 × TDM + 1.70 0.822 ≤ 0.001**
Major + Minor Ma mab a WUETDM = 0.003 × TDM + 1.22 0.792 ≤ 0.001**
Major + Minor Obatanpa WUETDM = 0.003 × TDM + 2.71 0.697 ≤ 0.001**
Major + Minor Combined WUETDM = 0.003 × TDM + 1.89 0.765 ≤ 0.001**
** Highly significant
The regression coefficient (slope of the linear regres-
sion model) values of 0.003 mm–1 for Obatanpa, 0.002
mm–1 for Mamaba and 0.003 mm–1 for Golden Crystal
(Ta b le 2 ) suggest that the maize cultivars generally be-
haved similarly during the major and minor cropping
seasons in terms of efficient use of soil water for bio-
mass production. Consequently, WUETDM and TDM data
for both cropping seasons and for each maize cultivar
were combined for a single linear regression model. The
same regression coefficient was obtained for each maize
cultivar but significantly different R2 value of 0.697 for
Obatanpa, 0.792 for Mamaba and 0.822 for Golden
Crystal (Ta b le 2 ). Additionally, linear regression analy-
sis of all WUETDM and TDM for all the maize cultivars
resulted in a unified linear regression model, WUETDM =
0.003 TDM + 1.89 with R2 value of 0.765 (Table 2).
Thus, a single linear model adequately describes the
relationship between biomass accumulation of the three
maize cultivars and their associated WUETDM for the
combined major and minor cropping seasons.
Linear regression of WUEGY against grain yield (GY)
for all the maize cultivars resulted in good linear models
with R2 of 0.996 and 0.992 for the major (Figure 1(a))
and minor (Figure 1(b)) cropping seasons, respectively,
indicating grain yield of these maize cultivars strongly
related to WUEGY. This strong agreement between
WUEGY and GY for the maize cultivars is in agreement
with results obtained by Adamtey et al. [8] for maize
grown in pots under greenhouse conditions. However,
the linear model between WUEGY and GY for all the ma-
ize cultivars combined for the major and minor cropping
seasons resulted in a linear model, WUE GY = 0.002 GY +
0.48 with R2 value of 0.548. Thus, the three maize culti-
vars partitioned biomass for grain production differently
for each of the cropping seasons (major and minor) in
view of the fact that seasonal rainfall was 502.4 mm for
the major cropping season and 290.7 mm for the minor
cropping sea son [6 ]. This, therefore, suggests that season
rainfall has an impact on biomass partitioning for grain
yield in maize and consequently has effects on WUEGY.
A linear model adequately described the relationship
between WUETDM and TDM for the maize cultivars Ma-
maba, Golden Crystal and Obatanpa for each of the ma-
jor and minor cropping seasons. Additionally, a unified
linear regression model adequately described the rela-
tionship between WUETDM and TDM applicable for both
the major and minor cropping seasons. Thus, the linear
regression models could be used to estimate the effi-
ciency with which the three maize cultivars used soil
moisture efficiently for total biomass production under
rain-fed conditions in the area of study using TDM as
inputs. Besides, the models developed could be useful
for quick assessment of WUETDM for the maize cultivars
using easily measured TDM. Aside this, the measure-
ment of WUE of crops is generally a tedious task which
involves actual evapotranspiration measurement, There-
fore, the developed WUE GY-GY linear models would go
a long way to assist in d etermining WUEGY of the maize
D. K. Asare et al. / Agricultural Sciences 2 (2011) 125-130
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
Figure 1. Linear regression between water use efficien-
cy and grain yields of three maize cultivars during the (a)
major and (b) minor cropping seasons.
cultivars and, consequently, the soil water used for pro-
ducing the measured grain yield without estimating ac-
tual evapotranspiratin. However, linear models devel-
oped between WUEGY and GY were good for the maize
cultivars for each of the major and minor cropping sea-
sons, as seasonal rainfall had influence on biomass parti-
tioning for grain yield production of the maize cultivars.
Thus, a unified linear model for the combined major and
minor cropping seasons applicable for all the maize cul-
tivars resulted in a fairly good linear model. Conse-
quently, linear models developed between WUEGY and
GY appeared season specific for each of the cropping
seasons as biomass partitioning is sensitive to the
amount of seasonal rainfall.
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