IJERD – International Journal of Environmental and Rural Development (2012) 3-2

Research article
erdChanges in Turfgrass Leaf Chlorophyll Content and Some
Soil Characteristics as Influenced by Irrigation Treatments
THEMBINKOSI MATHOWA*
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
Email: tmathowa@yahoo.com

WILAILAK CHINACHIT
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

PONGSAK YANGYUEN
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

SUPAT ISARANGKOOL NA AYUTTHAYA
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
Received 14 December 2011

Accepted 18 April 2012(*: Corresponding Author)

Abstract In plants, less water causes photosynthesis reduction whereas excessive water
reduces the soil nutrients. These effects induce stunted plant growth. The aim of this work
was to study the changes in leaf chlorophyll content and some soil characteristics of thenative common bermudagrass (Cynodon dactylon L.) as influenced by irrigation treatments. Two experiments, open bottom 4 x 1 m concrete blocks and closed bottom pots
were set up during the dry season from January to May 2011 at the Horticultural Section,
Faculty of Agriculture, Khon Kaen University. The experimental designs were randomized
complete block design (RCBD) with 4 daily irrigation levels; 0.50 evaporation pan(0.50Epan), 0.75Epan, 1.00Epan (control) and 1.25Epan. The results showed that 1.25Epan irrigation in open bottom concrete blocks significantly increased leaching of essential soil nutrients and decreased leaf chlorophyll content. The 0.50Epan irrigation treatment in pot experiment which was meant to resemble drought conditions had the lowest values in leaf
chlorophyll content for the first two months. However, there were no differences in leaf
chlorophyll content in all the treatments for the last two months. Moreover, the soil nutrients in all the treatments were not leached out in the closed bottom pot experiment. Therefore, the optimum watering amount should be taken into consideration.
Keywords photosynthesis, soil nutrients, water logging, water stress

INTRODUCTION
Chlorophyll is a molecule that performs photosynthesis, and it is found in the chloroplasts of green
plants. This molecule is also responsible for the visual green colour in plants (Cheng et al., 2007;
Fu and Dernoeden, 2009). Changes in chlorophyll content could occur as a result of nutrients deficiencies or exposure to environmental stress such as water stress (Mohesenzadeh et al., 2006) andsoluble salts (Hameed and Ashraf, 2008). Generally, high soil fertility has been associated with theincrease in total chlorophyll concentration (Minotta and Pinzauti, 1996; Cheng et al., 2007). Moderate soil drying and infrequent irrigation was reported to have increased leaf chlorophyll content(Jiang and Huang, 2001; DaCosta and Huang, 2006; Fu and Dernoeden, 2009). However, Alshehhi
et al. (2010) found out that chlorophyll b and total chlorophyll (a+b) contents did not present significant differences on the three warm season turfgasses studied under different irrigation regimes
in arid region, which reflects that there was no water stress.
Irrigation is an important factor in achieving the desired functions and aesthetics of theturfgrasses. It is aimed at sustaining turf quality and performance by maintaining a favorable soil
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water balance which can be achieved with a well-scheduled irrigation together with other appropriate inputs such as fertilizers (Kneebone et al., 1992). Water is utilized by the turf for the transportation of organic molecules, inorganic molecules and in overall structural support (Decoteau, 2005).
However, less or excessive water can have some detrimental effects on turfgrass growth due to water stress and the environment such as water logging and salinity problems (Qadir et al., 2003; Rose,
2004). Moreover, soil characteristics which are fundamental to turfgrass growth such as pH, EC,
CEC, the rate of organic matter decomposition, nutrients and exchangeable cations are affected byeither excessive or insufficient water (Decoteau, 2005; Barton et al., 2006; Harivandi et al., 2009).
Despite chlorophyll being an important parameter for plants growth and soil characteristics
playing a major role on plants growth as well, an observation of inconsistent reporting by the previous researchers along these areas was noticed. Therefore, the present study was aimed at evaluating the changes in native common bermudagrass leaf chlorophyll content and some soil characteristics as influenced by the irrigation treatments. Moreover, soil nutrients leaching were confirmedby 2 experiments in open and closed soil systems.
MATERIALS AND METHODSTwo experiments were set up during the dry season. In both experiments native common bermudagrass (Cynodon dactylon L.) was propagated using rhizomes. In experiment 1, 16 concrete
blocks with open bottoms were used, each measuring 4 x 1 m while experiment 2 was comprised of
12 pots with closed bottoms buried to ground level, each measuring 0.55 m surface diameter and a
depth of 0.35 m. The experiments were designed according to a randomized complete block design(RCBD) with four blocks and four replications for experiment 1, and three blocks and three replications for experiment 2. Four daily irrigation treatments were applied as follows; 50, 75, 100-control
and 125% (0.50Epan, 0.75Epan, 1.00Epan and 1.25Epan) replacement of the evaporation pan (Class A
pan; Epan) which was installed at the study area for treatments 1-4 respectively. The watering wasdone manually.
Experimental units were filled up with a well prepared mixture of soil, chicken manure, ricehusk and rice husk ash (1:1:1:1, v/v) to provide uniform soil conditions. The bulk density was 1.10
g cm-3 at 0-15 cm soil depth, and it contained 87.8% sand, 8.1% silt and 4.1% clay. The soil mixture was fermented for a month and some soil physical and chemical properties were determined asfollows; pH (1:1 soil: distilled water extract) and electrical conductivity (EC; 1:5 soil: distilled water extract) were measured by conductivity meter (model: MPC227), cation exchange capacity(CEC) by ammonium saturation (Schollenberger and Simon, 1945), organic matter (OM) (Walkley,1947), total nitrogen (N) content by Kjeldahl method and measured by flow injection analyzer(model: 5012 Analyser) (Bremner, 1965), available phosphorus (P) by Bray II method (Bray and
Kurt, 1945), and both exchangeable potassium (K+) and (Ca2+) were measured by flame photometer(model: 410) after extraction with 1 N ammonium acetate pH 7.0. Also, soil characteristics were
determined at the end of the study. The turf was maintained at 1 cm canopy height by cutting andremoving the clippings from the experimental units.
Meteorological data was obtained from the agronomy section weather station, located 150 m
away from the study area (Table 1).
Leaf chlorophyll content was measured on monthly basis following a method described by
Arnon (1949). Chlorophyll was extracted by manual grinding 0.05 g of fresh leaf tissues with 80%
acetone using a pestle and mortar in dark room at room temperature. After extracting the chlorophyll, the extract was topped up with 80% acetone to 20 mL, and filtered through a filter paper intoa glass tube wrapped with aluminum foil. Residues were discarded, and the resulting solution wasthen transferred into a rectangular glass cuvette (path length 10 mm) and the absorbance was measured at 663 and 645 nm with a spectrophotometer (model: G10S UV-Vis). Final chlorophyll a, b
and total chlorophyll (a+b) were calculated using the following equations.

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Ca = [(12.7 × D663) – (2.69 × D645)] × DF
Cb = [(22.9 × D645) – (4.48 × D663)] × DF
Total chlorophyll (a+b) = [(8.02×D663) + (20.20×D645)] × DF

(1)
(2)
(3)

Where Ca is leaf chlorophyll a (mg g-1 fresh weight), Cb is leaf chlorophyll b (mg g-1 fresh
weight), DF is dilution factor, in this case was (20.05/50), D663 and D645 are spectrophotometer
absorbance at 663 nm and 645 nm respectively.
The data collected was subjected to analysis of variance (ANOVA) using the STATISTIX-8
program, where a significant F-test was observed and means comparison test was carried out using
Least  Significant  Difference  (LSD)  at  p≤0.05  to  separate  treatment  means.  
RESULTS AND DISCUSSION
The temperature ranged from 14.5oC to 34.6oC and average relative humidity was 79.6%. The
weekly Epan reading was 33.4 mm or approximately 4.77 mm day-1 (Table 1). However, there wasrainfall in mid March and April; so, compensation for rainfall by reducing the amount of watering
was done when rainfall occurred.
Table 1 Weekly averages of meteorological data measured during the period of the study
Month Week Min_Temp (oC)
Jan
3
14.5
4
16.2
Feb
1
15.9
2
19.1
3
19.3
4
22.7
Mar
1
22.4
2
20.6
3
18.6
4
18.9
Apr
1
19.8
2
19.7
3
18.7
4
17.6
Total

Max_Temp (oC)
27.9
29.4
28.5
33.8
33.7
33.5
34.6
33.5
29.4
28.4
34.5
33.3
32.9
33.1

RH (%)
85.6
81.9
83.6
80.0
82.1
85.1
75.9
76.9
76.9
76.9
77.0
76.1
77.3
79.4

Epan (mm)
34.0
48.0
30.0
30.0
33.0
25.0
37.0
36.0
33.0
32.0
37.0
24.0
38.0
30.0
467.0

Rainfall (mm)
12.0
18.0
6
36.0

Note: Dates for total evaporation in January week 3 and week 4 ranges from 12 th - 21st and 22nd - 31st respectively.
Total rainfall in March week 4 was from 22nd - 31st

Soil characteristics
pH, electrical conductivity (EC), and cation exchange capacity CEC: The pH tended to increase in high irrigation treatments in both experiments. The values in this work were in the rangeof the general suggestion, which recommends soil pH between 5.5 and 7.5 for nutrients uptake byturfgrasses (Bell, 2011). The comparison between open and closed systems clearly differed in EC
parameter. The open system had lower EC while the closed system had higher EC as compared tothe composite soil sample value. This evidence indicated that the open system had soil nutrientsleaching in the root zone to the deeper soil profile. The consideration in the 4 treatments for bothexperiments showed that high amount of watering (1.25Epan) decreased the EC (Table 2). Nevertheless, the observed increase in EC from the closed system experiment could be attributed to the fertilizer applied two times in March and April.
The CEC in open system decreased with the increase in irrigation amount while the opposite
was revealed in the closed system. Also, the reduction in CEC with high irrigation could be relatedwith nutrients leaching out from the root zone (Qadir et al., 2003; Rose, 2004; Bell, 2011).
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Organic matter (OM), Nitrogen (N) and Phosphorus (P): In open system experiment, OM significantly decreased in 1.25Epan irrigation and all treatments were under the composite soil sample(Table 2). This evidence may be the same with EC and CEC; where high leaching of the soil nutrients was observed in open system experiment. Normally, OM is related with N in the soil. Our results revealed that the open system had the lowest OM and N as compared to the closed system. In
addition, high irrigation in open system had the lowest OM and N. Comparing OM and N with thecomposite soil sample, and with the standard soil value (Bell, 2011), the values in this experimentwere higher in OM and N levels.
Similarly, the closed system experiment had higher P when compared to open system. Also,
for the high irrigation treatment in open system, P was leached out (Table 2).
Exchangeable cations; Potassium (K+) and Calcium (Ca2+): When comparing exchangeable K+of the two experiments, the results revealed high decrease in open system which was lower than thecomposite soil sample. This relates to the observed decrease in EC (Table 2). The watering induced
leaching of exchangeable K+ from the top soil. Bell (2011) reported that it is more difficult to maintain K+ levels on soils with very high sand contents because K+ is not tightly bound and leaches out
easily. However, the closed system had accumulated exchangeable K +. In detail, the treatments inclosed system experiment, 0.75Epan and 1.00Epan irrigation had lower exchangeable K+ as comparedto 1.25Epan irrigation. Mathowa et al. (2011) reported increase in shoot biomass in 0.75Epan and1.00Epan irrigation treatments as opposed to the 1.25Epan irrigation. Therefore, the observed decrease could also be attributed to exchangeable K+ being utilized for shoot biomass production.
On the contrary, the irrigation treatments seem to have had no effect on exchangeable Ca 2+leaching (Table 2), because of the characteristic of Ca2+ as an immobile nutrient.
Table 2 Soil characteristics as influenced by irrigation treatments in both open bottom
concrete blocks and closed bottom pots experiments
pH 1:1
H2O

EC 1:5
H2O
dS m-1

CEC
(cmol
kg-1)

OM
(%)

Total N(%)

Available P Exchangeable(mg kg-1)
K+ (mg kg-1)

Exchangeable
Ca2+ (mg kg-1)

Composite
7.2
0.7
9.9
3.9
0.12
2199.51461.01300.0
SD
0.3
0.1
1.6
0.4
0.02
430.3
114.4
127.3
Treatments
Open bottom concrete blocks
0.50Epan
7.0b
0.5a
11.0a
3.4b
0.12b
1852.4c1051.9b
1900.0a
b
a
b
a
a
a
a
0.75Epan
7.1
0.5
10.6
3.5
0.13
2275.01149.31450.0c
b
c
d
c
b
b
b
1.00Epan
7.0
0.4
10.3
3.3
0.11
2142.31042.2
1400.0d
1.25Epan
7.3a
0.2d
10.4c
3.2d
0.10b
1749.2d866.9c1850.0b
F-test
*
**
**
**
*
**
**
**
LSD 0.05
0.18
0.01
0.02
0.02
0.02
10.73
17.79
8.22
CV (%)
0.80
0.62
0.05
0.15
4.73
0.17
0.54
0.16
Treatments
Closed bottom pots
0.50Epan
7.0b
1.8a
10.0d
3.9c
0.15c
2893.6a3141.1d1452.5c
b
b
c
c
b
c
c
0.75Epan
7.0
1.7
10.8
3.9
0.16
2771.23335.91550.0b
b
b
a
a
a
b
b
1.00Epan
7.1
1.7
11.7
4.6
0.18
2845.83555.11150.0d
1.25Epan
7.6a
1.4c
11.4b
4.2b
0.15c
2412.5d4139.5a1700.0aF-test
**
**
**
**
**
**
**
**
LSD 0.05
0.13
0.05
0.02
0.01
0.01
15.16
17.08
8.88
CV (%)
0.57
0.87
0.05
0.10
2.17
0.17
0.15
0.19
*  significant  at  p≤0.05,  **  highly  significant  at  p≤0.01,  standard  deviation  (SD).  Means  separated  by  LSD  Test  at  p≤0.05,  means within columns followed by the same letters are not significantly different.

Leaf Chlorophyll content
Chlorophyll a, b and total chlorophyll (a+b): In open system, chlorophyll a seemed to be positively correlated with the treatments for the first two months with 0.50E pan irrigation significantly
reducing the content. Contrary to the first two months, 0.50Epan and 0.75Epan showed the highest
content (Fig. 1A) The same trend was revealed for chlorophyll b and total chlorophyll (a+b) contents (Fig. 1B and 1C). Similar results; that is, the increase in chlorophyll content in 0.50Epan andⒸISERD184

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4.9
4.6
4.3
4.0
3.7
3.4
3.1
2.8
2.5
2.2
1.9
1.6
1.3
1.0
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0

0.50 Epan

0.75 Epan

1.00 Epan

1.25 EpanA

Leaf chlorophyll content (mg -1 FW)

Leaf chlorophyll content (mg -1 FW)

0.75Epan irrigation treatments were reported by Jiang and Huang (2001), and DaCosta and Huang(2006) found out that drought or lower amount of irrigation increase the chlorophyll content. It
seems as if turfgrass chlorophyll contents increase serves as an activator for biochemical processes
such as photosynthesis. Moreover, a sharp decrease in chlorophyll content for the control and1.25Epan irrigation at the end of the study could be attributed to the excessive irrigation which led tosome essential soil nutrients such as N and exchangeable K+ being leached out to the deeper soil
profile as shown in Table 2.
Similar trend in closed system (Fig. 2) to the one shown in open system (Fig.1) was revealed
for the first two months. However, there were no differences in the third and fourth months (Fig.2).
Water moves downwards to the deeper soil profile after rain or irrigation and it moves upwards toevaporate or transpire from the soil surface or plant leaves (Plaster, 2003). Therefore, the closed
bottom pot experiment was set up to counteract the upward movement of water. As a result nocompensation for less water in closed system, hence water stress could possibly explain the highdifferences among the treatments as opposed to the open system for the first two months (Fig.1 and
2). Due to the fact that the closed pots were able to retain essential soil nutrients such as N, P and
K+ (Table 2), this could be attributed to the increase observed in chlorophyll contents at the end of
the study. In support of our findings, Minotta and Pinzauti (1996) and Cheng et al. (2007) suggested that chlorophyll content progressively increase in high fertility soils.

B

C

Fertigation
8-Feb

8-Mar
7-Apr
Time intervals (dates)

5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
6.0
5.6
5.2
4.8
4.4
4.0
3.6
3.2
2.8
2.4
2.0

0.75 Epan

1.00 Epan

1.25 EpanA

B

C

Fertigation

8-Feb

30-Apr

0.50 Epan

8-Mar
7-Apr
Time intervals (dates)

30-AprFig. 1 Effect of irrigation regime on leaf chlo- Fig. 2 Effect of irrigation regime on leaf chlorophyll content
rophyll content
chlorophyll a (A), chlorophyll b (B) and total
chlorophyll (a+b) (C) of native common bermudagrass in open bottom concrete blocks. Verticalbars  are  LSD  values  (p≤0.05)ⒸISERD185

chlorophyll a (A), chlorophyll b (B) and total
chlorophyll (a+b) (C) of native common bermudagrass in closed bottom pots. Vertical bars are
LSD  values  (p≤0.05)

IJERD – International Journal of Environmental and Rural Development (2012) 3-2

CONCLUSIONS
Excessive irrigation in open system experiment led to leaching of essential plants nutrients and resulted in a significant decrease of leaf chlorophyll content. On the contrary, the closed system had
no leaching of essential plants nutrients as proved by the increase in chlorophyll content in the thirdand fourth months. Therefore, optimum irrigation can retain nutrients and increase chlorophyll content; this should be taken into consideration for irrigation amount.
ACKNOWLEDGEMENTS
Thanks to the Graduate School, Khon Kaen University for financial support, TICA scholarship, andAgronomy Soil and Plant Analysis Laboratory technicians for technical assistance.
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