Corn is one of the cultivated grain-cum-fodder crop with
tremendous yield potential grown round the year under irrigated conditions.
In many parts of the world, maize is the most important food stuff and
particular, provides the daily bread for the indigenous population of
rural areas. Maize is one of the most efficient field crop in producing
higher dry matter per unit quantity of water (Viswanatha et al.,
2002). During recent years, irrigated corn production has expanded rapidly
in Turkey. Corn has become a widely grown feed grown particularly as a
second crop after wheat or barley. The corn production in Turkey is about
2,200,000 tons of grain corn from 575,000 ha (NIS, 2004).
Irrigation water is the most important limiting factor
for agriculture during the hot and dry summer period. Limited availability
of irrigation water requires fundamental changes in irrigation management
or urges the application of water saving methods. A generally applicable
procedure is to asses the benefits of changing irrigation water management
based on deficit irrigation, which is the practice deliberately under-irrigation
field crops. Under these conditions, there is one way for farmers to maximize
their profit from corn production. The way is to determine the water-yield
relationships of corn crops and to choose the most appropriate irrigation
scheduling for saving irrigation water and timing (Pandey et al.,
2000; Dagdelen et al., 2006; Doorenbos and Kassam, 1979; Howell
et al., 1997).
Water is the prime natural resource which very often
becomes costly and limiting input particular in semi-arid tropics and
needs to be judiciously used to reap the maximum benefit of the other
inputs. Drip irrigation provides the efficient use of limited water with
increased water use efficiency (Viswanatha et al., 2002). The higher
green cob yield with increased moisture level was reported by Braunworth
and Mack (1989).
Common irrigation methods used for corn production in
the region are wild flooding, furrow and sprinkler irrigation. In general,
the farmers over irrigate, resulting in high water losses and low irrigation
efficient, thus creating drainage and salinity problems (Yazar et al.,
The amount and timing of irrigation are important for
efficient use of applied water and for maximizing crop yields. Predicting
yield response to water use corn is important in developing strategies
and decision-making for use of by farmers and their advisors and the researchers
for irrigation management under limited water conditions (Dagdelen et
Doorenbos and Kassam (1979) indicated that the maximum
corn yield was usually obtained when the corn plants were irrigated 50%
of available water capacity.
The objectives of this study were to determine effects
of different irrigation frequencies and intervals on yield and yield components
of corn under the Middle Black Sea climatic conditions of Turkey.
MATERIALS AND METHODS
The experiment was conducted at the Agricultural Faculty Research Station
of Ondokuz Mayis University, Samsun, Turkey during 2005 corn growing season.
The station has the latitude of 41o121` N, the longitude 36o115`E
and altitude 180 m above sea level. The soil of the experimental site
is clay-loam textured throughout the profile. The water holding capacity
of the soil is 182 mm in the 90 cm profile. Some physical properties are
shown in Table 1.
The Electrical Conductivity (EC) of irrigation water
was 0.41 dS m-1 and the sodium adsorption rate was 0.42 which
are not risk for growing corn plants (Ayers and Westcot, 1985).
Long-term annual precipitation in the region is about
683.2 mm, with more than 80% of it falling from October to April. Water
loss by evapotranspiration is very high during the growing season. Therefore,
irrigation is needed in during the growing season to maintain and enchance
crop growth and yield.
Based on the daily evaporation from a standard class
A pan evaporimeter which installed at the field. The meteorological sub-station
located at about 300 m from the site of experimentation, the calculated
quantity of water was given under drip irrigation levels.
In this study, RX-788 hybrid sweet corn (Zea mays
saccharata) variety was used as the crop material. Fertilizer applications
were based on soil analysis results and all the plots received the same
amount of total fertilizer. The recommended dose of 75 kg ha-1
pure N, P and K (15, 15, 15 composite) before sowing and additional nitrogen
dose of 115 kg ha-1 was applied as Ammonium nitrate 50% when
the plant reach to 0.4-0.5 m in height.
The experiment was laid out in randomized block with
three replications. Each plot consisted of five rows of 5 m in length.
The plants were grown 0.7 m apart between the rows with 0.25 m spacing
each row. The crop was sown on June 3, 2005 according to spacing mentioned.
There was a 2.0 m space between each plot. For three treatments, irrigation
was applied when approximately 50% of the available soil water was consumed
in the root zone (B), irrigation was applied when approximately 30% of
the available soil water was consumed in the root zone (C), irrigation
was applied when approximately 15% of the available soil water was consumed
in the root zone (D) and for one treatments was non-irrigated.
The drip irrigation system consisted of four manifolds
and distribution lines. Drip laterals of 16 mm in diameter had in-line
emitters spaced 25 cm apart, each delivering 41 h-1 at the
pressure 100 kPa.
First irrigation water was applied to all treatments,
during the experiments in 2005 to bring water content in 0-90 cm soil
depth up to level of field capacity. Irrigation treatments were started
using drip irrigation system when the water content of the soil decreased
to treatment level of available soil water.
Crop water consumption in the treatments was calculated
using Eq. 1 (Heerman, 1985).
||The evapotranspirations (mm).
||The rainfall (mm).
||The depth of irrigation (mm).
||The depth of drainage (mm).
||The change of the soil water storage in the measured soil depth.
Since the amount of irrigation water was only sufficient
to bring the water deficit to the field capacity, drainage was neglected.
The water use-yield relationship was determined using
the Stewart`s model (Stewart et al., 1977) as follows:
||Actual yield (t ha-1).
||The maximum harvested yield (t ha-1).
||The yield response factor.
||The actual evapotranspiration (mm).
The maximum evapotranspiration (mm). Corresponding
to Ym, 1 – (Ya/Ym) is the
relative yield decrease.
1 – (Eta/ETm)=The relative
Doorenbos and Kassam (1979), stated that, when Ky<1,
yield loss is less important than evapotranspiration deficit; when Ky>1,
yield loss is more important than evapotranspiration deficit and when
Ky=1, yield is equal to evapotranspiration deficit.
The crop was harvested on September 11, 2005 and the
plant status, available soil moisture (%) water requirement, water use
efficiency were recorded and subjected to statistical analysis.
RESULTS AND DISCUSSION
There is no irrigation applied to treatment A; four irrigations applied
to treatment B; six irrigations applied to treatment C and thirteen irrigations
applied to treatment D for corn during the growing season. The amount
of irrigation water applied varied from 285.71 to 257.14 mm in irrigated
treatments. As expected, the highest grain corn yield occurred in the
short irrigation interval. Treatment D occurred with highest grain corn
yield because of corn did not take any stress with more often irrigation
Data obtained from the study showed that the corn grain yield was significantly
(p<0.01) affected by irrigation treatments. Decreasing irrigation intervals
resulted in relatively higher yield. The maximum yield was obtained at
treatment D (29.16 t ha-1; B (21.59 t ha-1); C (19.15
t ha-1) and A (7.98 t ha-1), respectively (Table
At the no irrigation, 4, 6 and 13 day irrigation frequencies,
the rates of relative yield were 27.4, 74.0, 65.7 and 100%, respectively.
The lowest grain yield was observed in the non irrigation treatment since
low humidity and high air temperatures cause plant stomas to close, resulting
in less assimilation due to a decreased CO2 uptake for photosynthesis
(Oktem et al., 2003).
Since water stress cause a decrease in leaf area (Jamiesson
et al., 1995; Stone et al., 2001), a reduction in yield
is observed because of low photosynthesis. Pandey et al. (2000)
reported that the highest leaf area index for corn was obtained in well
The relationships between seasonal irrigation frequencies and corn grain
yield have been evaluated for experimental year (Fig. 1).
The relationships between seasonal irrigation frequencies
and corn grain yield was linear (p<0.01). The linear relation Y = 1.4933(I)
+ 10.884 (R2 = 0.86) were found of corn grain yield. The linear
relation of corn grain yield to water use is in agreement with other studies
for corn (Howell et al., 1995; Dagdelen et al., 2006).
Total No. of irrigation,
amount of irrigation applied and yield of corn for the experiment
period in 2005
|There are no statistical differences
among same letter(s) at 0.01 level according LDS test
The relationship between corn grain
yield and seasonal irrigation frequencies and irrigation intervals
In this study, the highest corn grain yield was obtained
from the treatment D. maximum grain corn yield was found that 29.16 t
ha-1 with 13 irrigation application with 214 mm ha-1
water amount for each irrigation. Grain corn yield was reduced as the
irrigation application decreased. The reductions in relative yield were
74.0% (B), 65.7% (C) and 27.4% (A). The results of the research indicate
that 13 irrigation applications in corn growing season by a drip system
would be optimal for corn grown in semi-arid regions similar to the area
in where this study was conducted.