Growth and physiological responses of sugarcane to drought stress at an early growth stage
ISSN 2588-1299
VJAS 2019; 2(4): 451-460
Vietnam Journal
of Agricultural
Sciences
Growth and Physiological Responses of
Sugarcane to Drought Stress at an Early
Growth Stage
Bui The Khuynh, Vu Ngoc Thang, Vu Dinh Chinh &
Pham Thi Thom
Faculty of Agronomy, Vietnam National University of Agriculture, Hanoi 131000, Vietnam
Abstract
A pot experiment was conducted in a net house to evaluate the effects
of drought stress (a 20-day water withholding treatment from 100-
120 days after planting) on the growth and physiology of five
sugarcane cultivars. The results showed that water stress at an early
stage significantly affected sugarcane growth and physiology.
Water stress resulted in reductions in plant height, stalk diameter,
and leaf number of sugarcane, in addition to reductions in the
photosynthetic pigment content, Fv/Fm, and SPAD (Soil Plant
Analysis Development) readings after the 20-day withholding
water period (120 DAP), and in stem, root, and leaf fresh weights,
and leaf area at 150 DAP. Besides, drought stress led to increases
in stomata density and decreases in stomata length. Variation was
also found among the cultivars in response to water stress.
Significant genotypic differences in stem fresh weight and leaf
area under water stress among the cultivars were observed. The
highest value of stem fresh weight under stressed conditions was
recorded in ROC22 (50.6g), followed by QĐ159 (46.5g), ROC16
(46.2g), ROC10 (46.1g), and VL06 (44.4g). However, the highest
DTI was recorded in ROC16, followed by VL06, ROC10, QĐ93-
159, and ROC22, respectively.
Keywords
Sugarcane, drought stress, growth, physiological response
Introduction
Received: June 9, 2019
Drought is considered a major abiotic stress that limits crop
production, resulting in severe reductions of their growth rate and
development (Begcy et al., 2012). Sugarcane (Saccharum spp.) is an
important crop used in the production of approximately 60% of the
global sugar supply as well as in the production of ethanol and bio-
energy (Amalraj et al., 2010). As a C4 plant with a high
photosynthetic capacity, sugarcane is highly dependent on water
Accepted: November 2, 2019
Correspondence to
ORCID
Khuynh T. Bui
752X
451
Growth and Physiological Responses of Sugarcane to Drought Stress at an Early Growth Stage
availability. Sugarcane is mostly cultivated in
tropical and sub-tropical rain-fed regions on both
sides of the equator (from 35o North to 35o South)
(Silva et al., 2013). In many of these regions,
rainfall does not provide the amount of water
required for the growth and photosynthetic
activities of the crop, and thus water shortages
remain a major limiting factor for achieving high
yields of sugarcane. Even in humid tropical areas,
inequality in rainfall distribution leads to
reductions in growth or yield loss (Silva et al.,
2013). A yield loss up to 60% due to drought has
been recorded in sugarcane (Robertson et al.,
1999). In Vietnam, the largest growing region of
sugarcane is located along the central coast where
drought is a recurring problem. Apart from
University of Agriculture. The mature stalks (8
months old) of five cultivars were selected, cut
into short pieces of which each had one active
bud, and used for propagating in germination
trays containing moist sand. The uniformly
germinated seedlings (buds 5-7cm in height)
were then transplanted into plastic containers
with the dimensions of 25cm in diameter and
35cm in height, and filled with 15kg of dry soil.
A two factorial experiment was laid out with
five replications following
a
completely
randomized design (CRD). The two water
regimes (field capacity as the control and drought
stress followed by recovery) were designated
factor A, while the five sugarcane cultivars were
designated factor B. Water was supplied to all the
treatments at the field capacity level from the
time of seed cane planting to 100 days after
planting (100 DAP). For the drought stress
treatment, water was withheld for 20 days from
100 to 120 DAP. Re-watering then was done in
the drought stress treatment to bring the soil back
to the level of field capacity and maintained in
that condition from 120 to 150 DAP. Soil
moisture was regularly measured at a depth of 20
cm using a soil tester Takemura DM15 (Japan)
every five days during the drought stress period.
Mean values of the recorded soil moistures in the
stressed treatment ranged from 78-85%, 75-82%,
62-68%, and 46-54% on the 5th, 10th, 15th, and
20th days of withholding water, respectively.
irrigation
practices,
drought
tolerance
improvement is required to alleviate drought and
water deficit problems, and to reduce yield losses.
Successful selection and breeding for cultivars
with drought tolerance can only be achieved when
the mechanisms underlying drought tolerance in
sugarcane are fully understood. Better
understanding of the physiological mechanisms
employed by the plant to better cope with drought
and water deficits will enhance the success rate in
selecting and breeding sugarcane for drought
tolerance (Silva et al., 2013). Thus, the objectives
of this study were to evaluate the effects of a water
deficit on the growth of five sugarcane cultivars
and analyze the genotypic differences in their
levels of drought tolerance.
Measurements
Materials and Methods
Plant height, stalk diameter, and leaf number
were measured at 100, 120 (end of the drought
stress treatment), and 150 DAP (30 days after re-
watering). The number of fully expanded leaves
was counted, and the center point of the stalk was
measured for stalk diameter using a vernier caliper.
Plant culture and water deficit treatment
Five sugarcane cultivars (Table 1) were
used in this study. A pot experiment was
conducted in greenhouse conditions at the
Faculty of Agronomy, Vietnam National
Table 1. Origin of the five sugarcane cultivars used in the study
Cultivar
Origin
QĐ93-159 (Yuetang 93-159)
ROC10
GSIRI, China
TSRI, Taiwan
TSRI, Taiwan
TSRI, Taiwan
TSRI, Taiwan
ROC16
ROC22
Vien Lam 6 (VL6)
Note: NTSRI: Taiwan Sugar Research Institute; GSIRI: Guangzhou Sugarcane Industry Research Institute.
Vietnam Journal of Agricultural Sciences
452
Bui The Khuynh et al. (2019)
Stomatal density and size were measured
according to the methods of Camargo & Marenco
(2011). The youngest fully expanded leaves (5
leaves and 4 samples per leaf) were selected, and
the midrib vein was removed. Stomatal density
and stomatal size were determined from nail
polish imprints taken from both the adaxial and
abaxial leaf surfaces. Stomata were counted by
calculating the view field using a stage
micrometer placed under the microscope (Nikon
Ys100) with a 10x objective lens. Stomatal size
was measured from a sample of 20 stomata per
leaf at 100x magnification.
(version 7.2) and Sigmaplot 12.5. Treatment
means were compared using the least significant
difference (LSD) test.
Results and discussion
Plant height, stalk diameter, and leaf number
Drought stress can reduce leaf size, decrease
stem growth and root expansion, increase hair
density on leaves and stems, and alter plant and
water relations (Farooq et al., 2012). After 20
days of withholding water, significant reductions
in plant height, stalk diameter, and leaf number
were recorded in the five cultivars (Table 2). This
is consistent with the findings of Silva et al.
(2008) and Smith et al. (2005) who reported that
cane elongation and stalk height were negatively
and strongly affected by drought. At 150 DAP
(30 days after re-watering), the plant height and
stalk diameter of all the cultivars had not fully
recovered as large reductions in stalk diameter
and plant height were still observed in the
stressed treatments among the five cultivars.
Significant differences among the five sugarcane
cultivars were recorded in plant height, stalk
diameter, and leaf number in the stressed period
(120 DAP) and after the recovery period (150
DAP). At 120 DAP, the highest plant height was
observed in ROC16 (140.5cm), followed by
ROC22, QĐ93-159, ROC10, and VL06 with
values of 126.0, 112.8, 98.7, and 79.5cm,
respectively. The reduction of stem height may
have been caused by the low soil water potential
which resulted in smaller leaf sizes and a smaller
number of leaves per plant (Reddy et al., 2003).
After the recovery period (150 DAP), stalk
diameters ranged from 10.9mm (in VL06) to
16.1mm (in ROC10). Jangpromma et al. (2012)
reported that drought stress did not lead to
significant variations in stalk diameter among
sugarcane cultivars after a 10-day water
withholding period. These differences compared
with the current study may indicate differences
among the cultivars, experimental conditions,
and duration of the stress treatment. A drought
occurring for more than 10 days was seen to result
in severe reductions in root development and
yield (Jangpromma et al., 2012).
Chlorophyll a fluorescence and photosynthetic
pigments measurements
The emission of chlorophyll a fluorescence
was evaluated at 12:00 pm, using a modulated
fluorometer (Opti-Sciences, OS30p+, USA), as
described by Medeiros et al. (2013). The initial
fluorescence (F0), the maximum fluorescence
(Fm), and the maximum quantum efficiency of
photosystem II (Fv /Fm) were then recorded after
30 minutes of dark adaptation using leaf-clips on
the first fully expanded leaf.
For the quantification of chlorophyll a,
chlorophyll b, and the carotenoids, 0.1g of fresh,
fully expanded leaves was collected, ground, and
soaked in 10mL of 90% acetone for 48h.
Absorbance readings at the wavelengths of 663,
647, and 470nm were measured in
a
spectrophotometer and used for the calculation of
the chlorophyll a, chlorophyll b, and carotenoid
contents (Arnold, 1949), and expressed as mg g-
1
fresh weight (FW). Root fresh weight, stem
fresh weight, leaf fresh weight, and leaf area
were measured at 150 DAP. SPAD chlorophyll
readings were measured at 100, 110, and 120
DAP using portable chlorophyll meters (SPAD-
502, Minolta, Japan). Drought tolerant index
(DTI) was determined following the methods of
Hoang et al. (2018) where DTI equaled the dry
stem weight under stressed conditions divided by
the dry weight under well-watered conditions.
Data analysis
Analysis of variance (ANOVA) tests on the
measured traits was performed using CropStat
453
Growth and Physiological Responses of Sugarcane to Drought Stress at an Early Growth Stage
Table 2. Plant height, stalk diameter, and leaf number of different sugarcane genotypes before (100 days after planting, DAP) and
after (120 DAP) a 20 day-drought, and 30 days after re-watering (150 DAP)
Plant height (cm plant-1)
Stalk diameter (mm)
Leaf number (leaves plant-1)
Treatment
100 DAP 120 DAP 150 DAP 100 DAP 120 DAP 150 DAP 100 DAP 120 DAP 150 DAP
ROC10 FC
82.3
84.0
100.0
96.6
103.7
90.3
89.5
85.6
53.6
61.5
14.6
83.2
98.7
97.0
87.6
105.2
92.2
152.0
146.0
200.0
160.0
175.3
148.4
158.3
148.5
141.5
83.1
8.7
8.3
8.6
8.9
8.2
7.7
8.5
8.3
6.0
6.2
2.0
8.4
8.7
7.9
8.4
13.1
9.4
17.1
15.1
14.2
12.4
17.9
13.8
17.3
13.0
11.6
10.3
2.2
7.0
7.0
5.3
5.6
6.6
6.0
5.3
5.3
6.3
6.3
0.8
7.0
5.5
6.3
5.3
9.7
6.7
7.0
5.7
9.0
6.3
7.0
6.3
8.6
5.6
1.4
8.2
6.3
7.7
6.7
10.7
7.0
8.0
4.7
8.7
6.3
9.3
7.7
6.0
4.3
1.8
8.8
6.3
7.5
8.5
Stressed
FC
ROC16
ROC22
161.7
119.3
139.0
112.3
117.5
108.0
92.4
12.2
8.7
Stressed
FC
12.2
8.2
Stressed
FC
QĐ93-
12.4
8.7
159
Stressed
FC
VL06
8.1
Stressed
68.9
7.1
LSD0.05C*W
12.0
16.9
1.6
Mean
ROC10
ROC16
ROC22
98.7
149.4
180.1
161.8
153.4
11.2
10.4
10.2
10.6
16.1
13.3
15.9
15.2
140.5
126.0
112.8
QĐ93-
159
VL06
57.5
10.3
86.0
83.6
6.5
79.5
8.5
112.3
11.9
165.5
137.4
7.5
6.6
1.4
7.6
1.2
10.9
1.5
6.3
0.5
6.1
6.0
0.3
7.9
7.2
1.0
5.1
1.3
LSD0.05C
Mean
FC
123.3
99.6
5.4
8.0
11.6
8.4
15.6
12.9
1.0
8.3
8.5
Stressed
8.0
6.1
6.0
LSD0.05W
CV%
0.9
0.7
0.6
0.8
10.1
6.3
6.5
14.8
9.6
8.9
11.1
14.7
Note: C: cultivar; W: water treatment; FC: field capacity (control); Stressed: drought stress treatment.
Stomatal density and size
length in the sugarcane cultivars under stressed
conditions compared to the control. Similar results
were observed by Meng et al. (1999) and Xu &
Zhou (2008) in which stomatal density was
negatively correlated with stomatal length under
different drought stress conditions. An increase
in stomatal density and a decrease in stomatal
size are regarded as important adaptations of
plants to drought and water deficits (Xu & Zhou,
2008). Although stomatal density was found to
increase under drought stress, the number of
stomata per leaf decreased as the leaf area was
reduced (Xu & Zhou, 2008). However, Yang et
al. (2007) showed that stomatal density varies
according to drought intensification. An increase
in stomatal density was recorded under light and
moderate drought, but a decrease was observed
in severe drought.
Leaf stomata play a central role in controlling
the exchange of CO2 and water vapor (Xu &
Zhou, 2008), and thus, are a crucial part of the
stress response of plants to water deficits. Under
drought, reductions in the photosynthetic rate can
be caused by both stomatal and non-stomatal
activities, depending on the drought intensity and
species (Chaves et al., 2003). Our results revealed
that the stomatal density was higher on the abaxial
surface than on the adaxial surface under both the
stressed and control (FC) conditions (Figure 1).
Drought stress led to significant increases in the
stomatal density on the abaxial surface of the
cultivars ROC10, ROC22, and QĐ93-159, and on
the adaxial surface of the cultivars ROC10,
ROC22, and VL06. In addition, the results
showed a decrease in the mean values of stomatal
Vietnam Journal of Agricultural Sciences
454
Bui The Khuynh et al. (2019)
(B)
(A)
FC
FC
Stressed
Stressed
100
80
60
40
20
0
300
250
200
150
100
50
**
*
ns
*
*
*
ns
**
ns
ns
0
ROC10 ROC16 ROC22 QĐ 159 VL 06
ROC10 ROC16 ROC22 QĐ 159 VL 06
Genotype
Genotype
(D)
(C)
ns
FC
Stressed
FC
Stressed
**
*
*
25
**
*
40
30
*
*
*
*
20
15
m
m
20
10
0
10
5
0
ROC10 ROC16 ROC22 QĐ 159 VL 06
ROC10 ROC16 ROC22 QĐ 159 VL 06
Genotype
Genotype
Note: ns = not significant; * = significant at p = 0.05; ** = significant at p = 0.01.
Figure 1. Mean values of stomatal density on the abaxial (A) and adaxial (B) surfaces,
and mean values of stomatal length on the abaxial (C) and adaxial (D) surfaces among cultivars
Photosynthetic pigments
chlorophyll a content, drought stress also
reduced the chlorophyll b content by 61%
compared to the control (FC), leading to changes
in the chlorophyll a/b ratio. However, no
significant differences in carotenoid content
were observed regardless of the cultivar or water
treatment. Similar results have also been observed
by Ashraf & Harris (2013) and Mafakheri et al.
(2010), who reported that reductions in the
chlorophyll content from drought stress are due to
Droughts have negative impacts on
photosynthetic pigments. Depending on the
drought intensity and duration, drought can cause
damage to pigments or even deterioration of
thylakoid membranes (Ashraf & Harris, 2013).
In this study, the results showed a decrease in
both chlorophyll a and b content as consequences
of drought stress in all the cultivars (Table 3).
While a decrease of 36% was found in the
455
Growth and Physiological Responses of Sugarcane to Drought Stress at an Early Growth Stage
Table 3. Effects of drought stress at an early stage on photosynthetic pigments at 120 DAP
Treatment
FC
Chla (mg g-1)
0.946
0.729
0.955
0.651
0.890
0.763
0.936
0.704
0.954
0.579
0.163
0.838
0.803
0.827
0.820
0.767
0.011
0.936
0.685
0.072
0.1
Chlb (mg g-1)
0.338
0.258
0.343
0.213
0.351
0.235
0.339
0.209
0.343
0.220
0.043
0.298
0.278
0.293
0.274
0.282
0.0285
0.343
0.227
0.018
8.3
Carotenoid (mg g-1)
0.208
0.203
0.207
0.203
0.206
0.208
0.207
0.198
0.202
0.197
0.009
0.206
0.205
0.207
0.203
0.202
0.006
0.206
0.202
0.041
2.6
Chla/Chlb
Total chl
ROC10
ROC16
ROC22
QĐ93-159
VL06
2.799
1.284
Stressed
2.826
0.987
FC
2.784
1.298
Stressed
FC
3.056
0.864
2.536
1.241
Stressed
FC
3.247
0.998
2.761
1.275
Stressed
FC
3.368
0.913
2.781)
1.297
Stressed
2.632
0.799
LSD0.05C*W
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Mean
ROC10
ROC16
ROC22
QĐ93-159
VL06
LSD0.05C
Mean
FC
Stressed
LSD0.05W
CV%
Note: C: cultivar; W: water treatment; FC: field capacity (control); Stressed: drought stress treatment.
SPAD readings and maximum photochemical
efficiency (Fv/Fm)
damage of the photosynthetic pigments and
deterioration of the thylakoid membranes. The
reduction of the chlorophyll content is mainly
due to the destruction of pigments caused by
oxidative damage when the plant is exposed to
severe drought stress. Generally, drought stress
leads to a greater reduction of the chlorophyll b
content than that of chlorophyll a and thus,
results in an increased ratio of chlorophyll a/b
(Ashraf & Harris, 2013). Under adverse
conditions such as drought, plants employ
different physiological and metabolic strategies
for survival. For instance, plants can synthesize
antioxidants such as ascorbate, glutathione, and
flavonoids (Medeiros et al., 2013), together
with increasing the activity of antioxidant
enzymes including peroxidase, superoxide
dismutase, and catalases.
The maximum photochemical efficiency
(Fv/Fm) is positively correlated with the
photosynthesis rate of a plant and thus, is used as
an important parameter for quantifying a plant’s
response to drought stress (Silva et al., 2013).
Maintaining a similar Fv/Fm ratio between plants
under drought stress and plants under well-
irrigated conditions indicates a high efficiency of
carbon assimilation and hence, the plant is better
able to adapt to the stressed conditions (Silva et
al., 2007). No significant differences in the
Fv/Fm ratios were found among all the cultivars
at 100 and 110 DAP. All the cultivars had a
Fv/Fm ratio of 0.74 to 0.78. However, at 120
DAP (20 days of withholding water), significant
differences in the Fv/Fm ratios were observed
Vietnam Journal of Agricultural Sciences
456
Bui The Khuynh et al. (2019)
Table 4. SPAD meter readings and Fv/Fm ratios of different sugarcane cultivars before (100 days after planting, DAP), after 10
days (110 DAP), and after 20 days of drought (120 DAP)
Fv/Fm
SPAD readings
Treatment
FC
100 DAP
110 DAP
120 DAP
100 DAP
110 DAP
120 DAP
150 DAP
ROC10
ROC16
ROC22
0.765
0.767
0.791
0.781
0.788
0.786
0.780
0.775
0.764
0.783
0.211
0.776
0.764
0.786
0.741
0.784
0.704
0.771
0.756
0.780
0.701
0.161
0.742
0.633
0.773
0.679
0.738
0.581
0.755
0.550
0.752
0.610
0.427
53.6
51.0
52.2
52.7
50.7
53.5
48.3
53.6
47.7
52.2
4.5
43.3
44.2
46.0
45.2
45.7
46.1
46.8
46.1
44.2
45.3
1.9
45.5
36.9
44.2
40.1
45.7
40.9
43.7
34.0
43.9
36.4
2.9
39.0
44.4
42.8
44.3
42.6
44.9
41.7
43.1
39.1
42.6
2.1
Stressed
FC
Stressed
FC
Stressed
FC
QĐ93-
159
Stressed
FC
VL06
Stressed
LSD 0.05C*W
Mean
ROC10
ROC16
ROC22
QĐ93-159
VL06
0.766
0.786
0.787
0.778
0.773
0.149
0.770
0.763
0.744
0.763
0.762
0.114
0.687
0.726
0.659
0.653
0.681
0.303
52.3
52.4
52.1
51.0
49.9
3.2
43.8
45.6
45.9
46.4
44.8
1.4
41.2
42.2
43.3
38.9
40.2
2.1
41.7
43.5
43.8
42.4
40.9
1.4
LSD0.05C
Mean
FC
0.778
0.778
0.145
0.779
0.742
0.132
0.752
0.610
0.191
50.5
52.6
2.2
45.2
45.3
0.9
44.6
37.7
1.3
41.2
43.9
2.0
Stressed
LSD 0.05W
CV%
1.6
1.2
3.7
5.1
2.5
4.2
2.7
Note: C: cultivar; W: water treatment; FC: field capacity (control); Stressed: drought treatment.
among cultivars. The highest Fv/Fm ratio value
was found in ROC16 (0.726) while the rest of
the cultivars had no significant differences.
Drought stress only led to a significant
reduction in the Fv/Fm ratio in the stressed
treatment compared with the control at 120
DAP (20 days of water withholding). A Fv/Fm
ratio value of less than 0.75 indicates the
beginning of stress and, therefore, a reduction
in the photosynthetic capacity of the plant
(Maxwell & Johnson, 2010). Low values of the
Fv/Fm ratio have also been reported by Graca
et al. (2010) and Silva et al. (2007) in
sugarcane under severe drought.
sugarcane, corn, and papaya (Jangproma et al.,
2010). Our results showed that drought
significantly reduced the SCMRs of plants under
stressed conditions at the end of the drought
stress treatment (120 DAP), which was
consistent with the findings of Silva et al. (2007).
A drought imposed 90 DAP led to reductions in
the SCMRs, and more severe reductions were
recorded in susceptible genotypes. SCMRs,
therefore, can be used for the identification of
drought-tolerant genotypes (Silva et al., 2007).
Significant differences in the SCMRs were
observed among the five cultivars at the end of
the drought stress treatment. The highest mean
SCMR value was recorded in ROC22 (43.8),
followed by ROC16 (42.2), and was lowest in
QĐ93-159 (38.6). Under stressed conditions, the
A SPAD chlorophyll meter reading (SCMR)
is considered a rapid assessment of the
chlorophyll content in many crops including
457
Growth and Physiological Responses of Sugarcane to Drought Stress at an Early Growth Stage
SCMRs were maintained at an average of 40 in
ROC22 and ROC16, which were significantly
higher compared to those in ROC10, VL06, and
QĐ93-159. This suggests a higher capacity of the
ROC22 and ROC16 plants to conserve their
photosynthetic pigment content during drought
stress. According to Silva et al. (2013), a SCMR
below 40 in sugarcane indicates the start of
chlorophyll deficiency, which affects the
photosynthetic activities of the plants. Thus, the
low SCMRs (below 40) recorded in ROC10,
VL06, and QĐ93-159 indicate drought stress
sensitivities. No significant difference in terms of
the SCMRs was found between the control and
stressed treatments at 30 days after re-watering
(150 DAP).
Plant fresh weight, leaf area (LA), and
drought tolerance index (DTI) at recovery
(150 DAP)
Sugarcane plants exposed to prolonged
drought have been reported to experience a
reduction in growth (Jaiphong et al., 2016). Our
results showed that root, leaf, and stem fresh
weights, and leaf area were significantly reduced
in plants under the drought treatment relative to
the control (Table 5). Fresh root weight was
reduced by 51.5% compared to the drought stress
treatment at 150 DAP. This matches with the
findings in early studies by Medeiros et al.
(2013), Jaiphong et al. (2016), and Silva et al.
(2013). Significant differences in root fresh
weight, leaf fresh weight, stem fresh weight, and
Table 5. Effects of drought stress at an early stage on the plant fresh weight, leaf area, and drought tolerance index (DTI) of five
cultivars at 150 DAP
Root fresh weight
(g plant-1)
Leaf fresh weight
(g plant-1)
Stem fresh weight
(g plant-1)
Leaf area
(cm2)
Drought tolerance
index (DTI)
Treatment
ROC10
FC
57.2
30.7
50
158.6
76.5
79.3
46.1
71.2
46.2
96.7
50.6
80.5
46.5
64.7
44.4
4.4
18.2
9.5
-
0.59
-
Stressed
FC
ROC16
ROC22
QĐ93-159
VL06
188.8
78.8
22.5
10.5
23
Stressed
FC
31.3
93.1
41.3
58.1
21.2
46.5
26.7
4.1
0.69
-
176.5
115.6
164.6
82.5
Stressed
FC
17.1
14.9
8.8
0.55
-
Stressed
FC
0.57
-
91.3
17.2
5.7
Stressed
54.9
0.68
LSD 0.05C*W
10.5
1.9
Mean
ROC10
ROC16
ROC22
QĐ93-159
43.9
40.6
67.2
39.6
117.5
133.8
146.1
123.5
62.7
58.7
73.6
63.5
13.9
16.5
20.1
11.8
VL06
36.6
73.1
54.5
11.4
LSD0.05C
2.8
7.4
3.1
1.3
Mean
FC
60.9
30.2
1.8
155.9
81.6
4.7
78.5
46.8
2
19.2
10.3
0.9
Stressed
LSD 0.05W
CV%
5.2
5.2
4.2
7.8
Note: C: cultivar; W: water treatment; FC: field capacity (control); Stressed: drought treatment.
Vietnam Journal of Agricultural Sciences
458
Bui The Khuynh et al. (2019)
leaf area were found among sugarcane cultivars.
The mean values of stem fresh weight ranged
from 54.5g (in VL06) to 73.6g (in ROC22).
Significant differences in stem fresh weight and
leaf area were also found among the cultivars
under drought stress. The highest value of stem
fresh weight under stressed conditions was
recorded in ROC22 (50.6g), followed by QĐ93-
159 (46.5g), ROC16 (46.2g), ROC10 (46.1g),
and VL06 (44.4g). Leaf area also varied among
the sugarcane cultivars and ranged from 11.4cm2
in VL06 to 20.1cm2 in ROC22. A reduction in
plant growth under water deficit conditions can
be seen as the consequence of the decrease in cell
elongation caused by the interruption of water
flow from the xylem to surrounding elongation
cells, the increase in cell sap concentration, and
the dehydration of the protoplasm (Nonami,
and VL06 (44.4g). However, the highest DTI
was recorded in ROC16, followed by VL06,
ROC10, QĐ93-159, and ROC22, respectively.
Conflicts of Interest
The authors declare no conflicts of interest.
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