J. Appl. Hort., 2(2):108-110, July-December, 2000
Effects of different irrigation methods and moisture regimes on
vegetative growth parameters of Starking Delicious apple trees
A. Halim Orta1, M. Emin Akçay2 and Tolga Erdem1
1
Department of Farm Structure and Structure and Irrigation, Faculty of Tekirdað Agriculture, University of Trakya
59030 – Tekirdað - Turkey. 2 Atatürk Horticulture Research Central Instýtute-Yalova-Turkey, E-Mail : horta@tu.tzf.edu.tr.
Abstract
This study was conducted to investigate the effects of different irrigation methods and regimes on vegetative growth of “Starking
Delicious” apple trees in Thrace conditions. Experiment was designed as split plots in the randomized block with three replications.
Drip and surface (ponding) irrigation methods were basic treatments; allowable depletion levels of soil moisture (40% and 70% of
available water holding capacity) in 120 cm soil depth were sub treatments. Seasonal evapotranspiration and total amount of irrigation
water in drip irrigation plots were lower than those of surface irrigation plots as 62.7% and 72.5%, respectively. Although, the effect of
irrigation regimes on vegetative growth parameters was non significant. Drip irrigation gave better results than surface irrigation
when irrigation water requirements, evapotranspiration and vegetative growth parameters were evaluated together. In conclusion, it
can be suggested that drip irrigation should to be preferred for apple trees in Thrace conditions and irrigation water should be applied
when moisture reaches 40% of available water holding capacity .
Key words: Apple trees, irrigation methods, water requirements, irrigation scheduling, evapotranspiration, vegetative growth
Introduction
Improvement of existing irrigation technologies is one of the
most important way out for irrigating maximum area with current
available water sources. Moreover, it is necessary to select most
suitable irrigation method for existing conditions to lay out and
operate the system properly. It is suggested that pressurized
irrigation methods should be used because of scarcity of water
resources in Thrace region of Turkey. But, surface irrigation
methods are commonly used for apple trees and irrigation water is
applied without taking any irrigation data into consideration.
Consequently, irrigation cost per unit area increases.
Many studies have been reported on the irrigation of apple trees
(Gergely, 1979; Middleton et al., 1981; Beukes and Weber, 1982;
Evans and Proebsting, 1985; Levin et al., 1985; Fluyurtse and
Roitman, 1986; Kulkov and Saidaliev, 1986; Assaf et al., 1989;
Tender and Czynczyk, 1997; Köksal et al., 1999). These studies
have consistently shown increase in vegetative growth parameters
and yield components of apple trees in drip irrigation method when
compared to the other irrigation method or no irrigation regimes.
The objective of this study was to evaluate the effects of irrigation
method and allowable depletion of available soil moisture as
irrigation threshold on vegetative growth parameters on apple trees
in Thrace conditions.
Materials and methods
Experiments were conducted in the orchard of Agricultural Faculty
of Tekirdað, Turkey, in 1997 and 1999, at 40o59′ N, 27o29′ E and
4 m altitude. The averages of annual temperature, relative humidity,
wind speed, sunshine duration and total precipitation are 13.7oC,
75%, 3.1 m/s, 6.5 h and 579.7 mm, respectively.
The soils in the research field are generally deep, moderately heavy
and heavy textured. There was no salinity, alkalinity and shallow
underground water.
Starking Delicious apple trees were planted at a spacing of 6 x 6 m
in 1989. Moreover, trees had not been irrigated until the beginning
of research. The size of plot was 24 m x 24 m and each plot had 16
apple trees. Measurements were done on 4 trees chosen in the
middle of the plots. The experiment was designed as split plots in
the randomized block with three replications. The experiment
consisted of two irrigation methods (main treatments) and two
allowable depletion levels of soil moisture (sub treatments), which
were as follows;
Main treatments
D=Drip irrigation, S=Surface (ponding) irrigation method,
Sub treatments
40% = Irrigation when 40% of available soil moisture was
consumed and 70%= Irrigation when 70% of available soil moisture
was consumed.
The irrigation water was taken from the municipal water distribution
system and conveyed to experimental plots by f 40 PVC main line.
Two lateral lines (f 16 PE and 4 atm. operating pressure) were laid
for each tree row in drip irrigation plots. Dripper spacing was chosen
as 90 cm taking soil characteristics into account therefore, wetting
rate was 30%. Dripper discharge rate was 4 l h-1 at 1 atm. operating
pressure. For the surface irrigation method, polietilen lateral lines
(f 20) were used to convey water to ponds arranged under each
tree with 3 m diameter. Irrigation water quality was analyzed as
C2S1.
Soil moisture content in each plot was monitored by neutron probe
Irrigation methods and mositure regimes on vegetative growth of apple trees
(CPN, 503 DR Hydroprobe). To do this, aluminum access tubes
were driven in 150 cm soil depth. Although, calibration equations
were obtained to every 15 cm soil layers, one equation was used
because there were not any significant differences between them
(Evett et al., 1993). Soil moisture content of the first 20 cm was
measured gravimetrically since it was not possible to monitor by
neutron probe. The measurement in 120 cm were done daily and
irrigation water was applied when 40% and 70% available holding
capacity was consumed. Irrigation was started in middle of the
May (when the flowering period was over) and stopped in
September. Evapotranspiration for decade periods were calculated
according to the method of water balance in 150 cm soil depth.
To determine vegetative growth parameters, the annual increasing
values of cross-section area of trunk and height of canopy tree
were measured before and after irrigation season. The cross-section
area of trunk was determined by measuring of trunk diameter at
the height 15 cm above the vaccination region. Also, number of
shoots, shoot lengths and number of flower clusters were measured
on three branch selected in different directions at the end of the
vegetative growth period (Köksal et al., 1999).
109
gave better results on the annual increase in values of cross-section
area of trunk. Although the annual increasing values of height of
canopy tree were not affected by treatments statistically, differences
on the years were found to be significant (Table 3).
Table 2. Effect of irrigation methods on the annual increasing
values of cross-section area of trunk (cm2)
Irrigation
Allowable depletion
1997
1999
method
level of soil moisture
Drip
63.42a1
a2
37.95 a
c
43.97 a
bc
53.89a
ab
40%
70%
Surface
40%
70%
16.95b
d
25.93b
d
23.39b
d
15.76b
d
1Duncan’s Multiple Range Test for years (p < 0.05)
2Duncan’s Multiple Range Test for interaction of year x irrigation
method x allowable depletion level of soil moisture (p < 0.01)
The results of vegetative growth parameters were statistically
analyzed by analysis of variance according to interaction of year x
irrigation method x allowable depletion level of soil moisture
(Yurtsever, 1984).
Table 3. Effect of irrigation methods on the annual increase in
tree canopy height (m)
Irrigation
Allowable depletion
1997
1999
method
level of soil moisture
Results and discussion
Drip
The total number of irrigation, the total amount of irrigation water
and seasonal evapotranspiration for each treatment are given in
Table 1. The total number of irrigation varied between 7-13.
Naturally, these values were maximum for treatments irrigated
when 40% of available soil moisture was consumed. According to
the total amount of irrigation water, water was saved in drip
irrigation treatments by 70.9% and 74.0% in first and second year,
respectively, than surface irrigation treatments. Besides, seasonal
evapotranspiration values were lower in drip irrigation treatments
than surface irrigation treatments by 60.5% in first year and 64.9%
in second year because a definite area is irrigated instead of full
area in drip irrigation method.
The research was conducted by fixed experiment design since apple
trees were planted before beginning of experiment. Therefore, the
results of two years were evaluated together. The effects of irrigation
treatments on annual increasing values of cross-section area of trunk
were found different between the years (Table 2). The annual
increasing values in second year were lower than those of first
year. This is probably because the trees were irrigated for the first
time and in first year naturally the response was higher. Also,
interaction of year x irrigation method x allowable depletion level
of soil moisture was found to be significant and Drip 40% treatment
Surface
0.44 a1
0.36 a
0.44 a
0.41 a
40%
70%
40%
70%
0.31 b
0.35 b
0.30 b
0.33 b
1Duncan’s Multiple Range Test for years ( p < 0.05)
The number of shoots and shoot lengths are presented in Table 4
and no difference on these vegetative parameters between the years
was obtain.
Table 4. Effect of irrigation methods on the number of shoots
and shoot lengths (cm)
Irrigation Allowable
Number of shoots Shoot length (cm)
method depletion
1997
1999
1997
1999
level of
soil moisture
Drip
Surface
40%
70%
40%
70%
31.67*
35.33
32.33
29.33
36.33
27.33
23.00
19.33
40.33
38.67
35.33
36.00
38.00
36.33
36.67
34.33
*Treatment effects were non significant
The number of flower clusters was affected by treatments and
years (Table 5). Specially, differences on irrigation method were
Table 1. The total number of irrigations, the total amount of irrigation water and seasonal evapotranspiration
Treatments
1997
1999
Irrigation
Irrigation
Number
Number
Seasonal
Allowable
Seasonal
Irrigation
water
method
of
of
evapotranspiration
depletion level of
evapotranspiration
water
applied (mm)
irrigations
irrigations
(mm)
soil moisture
(mm)
applied (mm)
Drip
40%
12
313.60
470.94
10
264.93
363.53
70%
9
307.74
460.16
7
235.13
347.23
Surface
40%
13
1096.01
1188.43
12
990.04
1058.21
70%
9
1039.66
1167.74
8
930.89
968.00
110
Journal of Applied Horticulture
found to be significant and drip irrigation method gave better
results than surface irrigation method. Also, drip irrigation
method was found to be first group according to interaction of
year x irrigation method. At evaluation of interaction of year x
irrigation method x allowable depletion level of soil moisture,
Drip+40% treatment gave better result.
Table 5. Effect of irrigation methods on the number of flower
clusters
Irrigation
Allowable depletion
1997
1999
method
level of soil moisture
Drip
40%
45.33 a1
38.00 b
a2
a
a3
b
a4
a
70%
42.67a
33.33b
a
a
a
b
b
b
Surface
40%
42.33a
29.00 b
b
b
a
c
b
b
70%
38.33a
30.33b
b
b
b
c
b
b
1: Duncan’s Multiple Range Test for years (p < 0.05)
2: Duncan’s Multiple Range Test for irrigation methods (p < 0.01)
3: Duncan’s Multiple Range Test for interaction of year x irrigation
method (p < 0.05)
4: Duncan’s Multiple Range Test for interaction of irrigation method x
allowable depletion level of soil moisture (p < 0.05).
Measurements of vegetative growth parameters in the first year were
greater then those of the second year because the trees were irrigated
for the first. Drip irrigation method gave better results when irrigation
water requirements, evapotranspiration and vegetative growth
parameters were evaluated together. Moreover, according to annual
increasing values of cross-sectional area of trunk and number of flower
cluster, the better results were measured in Drip 40% treatment. This
was also found for the experiments carried out in different places by
other researchers (Evans et al., 1985, Assaf et al., 1989, Köksal et al.,
1999).
In conclusion, it can be suggested that irrigation has to be applied
when 40% available water holding capacity was consumed under
drip irrigation method for apple trees in Thrace conditions,
Turkey.
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