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RESEARCH ARTICLE
Response of Sugarcane Cultivars to Chemical Ripeners During
the Mid-Period of Harvesting in Ethiopia
Netsanet Ayele
1
•Tamado Tana
2
•Philippus Daniel Riekert van Heerden
3,4
•Kebede W/Tsadik
5
•
Yibekal Alemayehu
5
Received: 18 October 2021 / Accepted: 18 March 2022 / Published online: 17 May 2022
ÓThe Author(s), under exclusive licence to Society for Sugar Research & Promotion 2022
Abstract The relatively high temperature at Kessem sug-
arcane plantation in Ethiopia was hypothesized to justify the
implementation of chemical ripeners as a strategic inter-
vention to combat poor cane quality. Accordingly, a field
experiment was carried out to assess the responsiveness of
four sugarcane varieties (B52-298, NCo334, C86-12, and
SP70-1284) to five ripener treatments: 2-chloroethylphos-
phonic acid (Ethephon
TM
, 480 g ai L
-1
) at 720 g ai ha
-1
,
fluazifop-p-butyl (Fusilade Forte
TM
, 150 g ai L
-1
)at
25.6 g ai ha
-1
, trinexapac-ethyl (Moddus
TM
, 250 g ai L
-1
)
at 250 g ai ha
-1
, 2-chloroethylphosphonic acid ?fluazi-
fop-p-butyl combination at the mentioned application rates,
trinexapac-ethyl ?fluazifop-p-butyl combination at the
mentioned application rates, and an untreated control. The
experiment was conducted in a factorial arrangement in a
randomized complete block design (RCBD) with three
replications. The results showed that stalk height, stalk
weight, sucrose content (%), and sucrose yield (t ha
-1
) were
affected by the main effect of ripener treatment, but there was
no significant cultivar x ripener treatment interaction for the
parameters collected. Overall, the sequential application
treatment of trinexapac-ethyl followed by fluazifop-p-butyl
28 days later performed the best and improved sucrose
content and sucrose yield by 2.64% unit and 2.15 t ha
-1
,
respectively. In economic terms, the trinexapac-
ethyl ?fluazifop-p-butyl sequential application treatment
resulted in a marginal rate of return of 2393%. Therefore, the
sequential trinexapac-ethyl ?fluazifop-p-butyl ripener
program was identified as a promising ripening strategy to be
evaluated on a commercial scale at the sugarcane plantations
in Ethiopia.
Keywords Chemical ripening
2-chloroethylphosphonic acid Fluazifop-p-butyl
Trinexapac-ethyl Sucrose yield
Introduction
Sugarcane (Saccharum spp. hybrid) is a major industrial
crop in Ethiopia because of its broad socioeconomic value
(Bharati et al. 2018), as well as the favorable climatic and
edaphic conditions for its growth (EIA 2012). Sugarcane is
generally cultivated for the production of sucrose, provid-
ing two-thirds of world sucrose supplies (Lakshmanan
et al. 2005), and its sucrose yield (t ha
-1
) is determined by
the cane yield (t ha
-1
) and sucrose content (%) of the stalk
(Ebrahim et al. 1998; Sachdeva et al. 2011). Consequently,
for a sugar mill to exist in the current competitive market, it
is crucial to maximize the sucrose content and sucrose
yield. As a strategic intervention, the Ethiopian Sugar
Industry could employ sucrose per unit stalk mass boosting
(ripening) mechanisms in areas where low stalk sucrose
content is a prominent challenge (Ayele et al. 2016).
&Netsanet Ayele
abnetay@gmail.com
1
Ethiopian Sugar Corporation, Research Centre, Eastern
Showa Zone, P.O. Box 15, Wonji, Ethiopia
2
Department of Crop Production, Faculty of Agriculture,
University of Eswatini, P.O. Luyengo, M 205, Luyengo,
Eswatini
3
South African Sugarcane Research Institute,
Mount Edgecombe 4300, South Africa
4
Department of Plant and Soil Sciences, University of
Pretoria, Pretoria 0028, South Africa
5
School of Plant Sciences, Haramaya University,
P.O. Box 138, Dire Dawa, Ethiopia
123
Sugar Tech (Jan-Feb 2023) 25(1):177–184
https://doi.org/10.1007/s12355-022-01139-x
The sucrose content of sugarcane transported to the mill
varies with the crushing period because ripening is influ-
enced by many factors including soil fertility, irrigation,
cultivars (van Heerden et al. 2014), weeds, pest and disease
presence, and length of the crushing season (James 2004).
Nevertheless, cool air temperature and water deficit are the
main factors influencing ripening (Cardozo and Sentelhas
2013). Photosynthesis and respiration, which are the two
major plant physiological processes, are affected by tem-
perature (Yamori et al. 2005). The optimum temperature
for growth and sucrose accumulation in the stalk has been
described to be 27 °C (Ebrahim et al. 1998). The presence
of adequate moisture for cane growth also reduces the
sucrose content of sugarcane during ripening due to the
high growth sink demand (Singels et al. 2000).
Conventionally, the Ethiopian sugarcane plantations
employ drying-off by with-holding irrigation for a few
weeks (5–9 weeks) before harvesting to facilitate cane
burning, harvesting operations, and to improve stalk
sucrose content (Getaneh and Negi 2014; Ayele et al.
2016). However, Gosnell and Lonsdale (1974) reported the
inadequacy of this method for ripening. Effective drying-
off requires accurate control over crop water supply (van
Heerden et al. 2015), and there is risk of reduction in cane
and sucrose yield due to excessive withholding of water
(Robertson et al. 1999).
Consequently, the application of chemical ripeners was
hypothesized to be the best strategy to improve competitive
advantage and to resolve the low sucrose content problem
at Kessem sugarcane plantation in Ethiopia. Many studies
have indicated that chemical ripeners can provide appre-
ciable increases in sucrose content above those attained by
natural ripening (Resende et al. 2000; van Heerden et al.
2014). Successful use of chemical ripeners for the purpose
of sugarcane ripening has already occurred in many
industries (Eastwood and Davis 1997; Li and Solomon
2003). Reports from South Africa (van Heerden 2019),
Swaziland (Rostron 1996), and Louisiana, the USA
(Spaunhorst et al. 2019) indicated improved sucrose con-
tent and economic benefit from the use of chemical
ripeners.
The ideal sugarcane ripener should increase sucrose
yield in a rapid, persistent, consistent, and economic way,
without damaging the crop, its following ratoon, or
neighboring crops (Resende et al. 2000). It should also
have low environmental toxicity and short half-life (East-
wood and Davis 1997). Since 1970, only a few chemicals
emerged that fulfilled most or all of these criteria, and they
have either herbicidal or hormonal modes of action.
Among the ripeners which are in use currently are gly-
phosate (e.g., Roundup
TM
), 2-chloroethylphosphonic acid
(e.g., Ethephon
TM
), fluazifop-p-butyl (e.g., Fusilade
Forte
TM
), and trinexapac-ethyl (e.g., Moddus
TM
) (van
Heerden et al. 2014).
Sugarcane cultivars differ from each other in their
responses to chemical ripeners (Spaunhorst et al. 2019). In
line with this, many reports confirmed the need for eval-
uation of sugarcane cultivars for their response to chemical
ripeners (Kingston and Rixon 2007; Rixon et al. 2007).
Thus, in every production environment, it is vital to eval-
uate existing sugarcane cultivars for their response to
chemical ripeners. However, at Kessem sugarcane planta-
tion, there is no information regarding the response of
commercial sugarcane cultivars to chemical ripeners.
Therefore, this study was undertaken to determine the
effects of chemical ripeners on the yield and quality of
sugarcane at this plantation.
Materials and Methods
Description of the Study Area
The experiment was conducted in the Central Rift Valley
of Ethiopia at Kessem sugarcane plantation (39°540E and
09°090N) from March 2018 to January 2019. The plan-
tation is located, at an elevation ranging from 750 to 850 m
above sea level. The soil was classified as Fluvisol and silty
clay in texture. Weather condition during the study period
is presented in Fig. 1.
Treatments and Experimental Design
Four sugarcane cultivars and five ripener treatments,
together with an untreated control, were used in the study.
The three single application treatments were
2-chloroethylphosphonic acid (Ethephon
TM
, 480 g ai L
-1
)
at 720 g ai ha
-1
, fluazifop-p-butyl (Fusilade Forte
TM
,
150 g ai L
-1
) at 25.6 g ai ha
-1
, and trinexapac-ethyl
(Moddus
TM
, 250 g ai L
-1
) at 250 g ai ha
-1
. The two
sequential application treatments were 2-chloroethylphos-
phonic acid (Ethephon
TM
, 480 g ai L
-1
) at 720 g ai ha
-1-
?fluazifop-p-butyl (Fusilade Forte
TM
, 150 g ai L
-1
)at
25.6 g ai ha
-1
and trinexapac-ethyl (Moddus
TM
,
250 g ai L
-1
) at 250 g ai ha
-1
?fluazifop-p-butyl (Fusi-
lade Forte
TM
, 150 g ai L
-1
) at 25.6 g ai ha
-1
. Four sug-
arcane cultivars B52-298, NCo334, C86-12, and SP70-
1284 were selected to be used as test crops. B52-298 and
NCo334 were under cultivation at the plantation since the
start of sugarcane processing in 2015. However, the culti-
vars C86-12 and SP70-1284 were selected based on their
performance at Metehara sugar plantation. The experiment
was conducted in a factorial arrangement in a randomized
complete block design (RCBD) with three replications.
178 Sugar Tech (Jan-Feb 2023) 25(1):177–184
123
Field Management and Experimental Procedure
The experiment was conducted on a plant cane crop, and
the study field was selected based on prior management
histories to ensure the absence of any stress-inducing
concerns such as water logging, irrigation inaccessibility,
and other related issues. The crop was planted using three
budded setts from eight-month-old stalk sourced from a
seed cane nursery that was well-fertilized, irrigated, and
disease-free. Throughout the growing season, irrigation
was delivered in the furrows until two weeks before har-
vest. At two-and-a-half-month crop age, 200 kg ha
-1
of
urea (46% nitrogen) was applied manually. Weeding was
conducted by hand as required. During the growth season,
field inspections were undertaken on a regular basis, and no
disease or insect pests were observed.
Water volumes of 431 L ha
-1
were used to deliver the
ripener spray mixes. Each plot consisted of 4 cane rows
measuring 6 m long and 1.45 m row spacing with a total
plot area of 34.8 m
2
. Application of the ripeners was
conducted using a high clearance boom frame with
motorized knapsack sprayer operating at 100 kPa pressure
at an average height of 0.5 m above the canopy of the crop.
Spray mixtures were administered through two flood-jet
nozzles, used to avoid chemical drift effects, spaced 0.5 m
apart. Spraying of the ripeners was conducted early in the
morning when the wind was calm. The age of harvesting
was 10 months after planting, and the single treatments
2-chloroethylphosphonic acid, trinexapac-ethyl and fluazi-
fop-p-butyl were applied 80, 70 and 42 days before har-
vest. For the sequential combination treatments,
2-chloroethylphosphonic acid was applied 80 days before
harvest followed by fluazifop-p-butyl 42 days (6 weeks)
ahead of harvest. Similarly, trinexapac-ethyl was applied
70 days before harvest followed by fluazifop-p-butyl
42 days prior to harvest.
Data Collected
At harvest, samples were taken from the two center cane
rows in each plot. Stalk height was determined from twenty
stalks per plot by measuring the length of stalks from the
ground to top visible dewlap leaf. Millable stalk weight
was determined from the combined twenty stalks per plot
using a weighing balance. Cane yield was determined from
the net plot area by weighing all the stalks using a weighing
balance, and then, plot weights were converted to a hectare
basis.
Brix (percent) was calculated using a ten stalk sample
collected randomly from each plot. The stalks were crushed
in a crushing mill, and the juice was analyzed using a
bench refractometer (Rudolph Research, Model J157). A
saccharimeter was used to determine Pol (%) from the
same juice (Rudolph Research, Analytical Autopol 880).
Purity (%) was calculated by multiplying the ratio of Pol
(%) to Brix (%) by 100. Finally, the sucrose content (%) of
cane was calculated as described by Berg (1972):
Sucrose content %ðÞ¼pol %Brix%pol%ðÞ0:61½0:75:
The non-sucrose factor is 0.61, while the crop factor is
0.75. The sucrose yield (t ha
-1
) was calculated by
multiplying the cane yield (t ha
-1
) by the sucrose content
(%) of the cane.
Data Analysis
To analyze the data, SAS version 9.2’s PROC GLM pro-
cedure was employed (SAS 2009). The Tukey’s
Fig. 1 Monthly total rainfall
(RF) distribution, relative
humidity (RH), the mean
maximum (T
max
) and minimum
(T
min
) temperature variations
during the study period at
Kessem Sugar Estate from
March 2018 to January 2019
Sugar Tech (Jan-Feb 2023) 25(1):177–184 179
123
Studentized Range (HSD) test was used to compare treat-
ment means for the measured parameters at a 5% level of
significance. The Kolmogorov–Smirnov test was used to
determine whether the data distribution was normal.
The economic feasibility of the ripener treatments was
determined utilizing CIMMYT’s partial budget method-
ological approach (CIMMYT 1988). Only expenditures
that differed across the ripener treatments were considered
in the partial budget analysis. As a result, the partial budget
did not include production costs, which were not relevant
to the ripening treatment comparisons. Thus, the net benefit
estimated per treatment does not equate to profit (income).
The average experimental sucrose yield data were adjusted
downwards by 10% to reflect the difference between the
experimental plot sucrose yield and the sucrose yield that
the plantation would expect under commercial condition
(CIMMYT 1988).
The adjusted sucrose yield was multiplied by the sucrose
selling price to calculate sales revenue. Then, for each
treatment, the gross field benefit was computed by sum-
ming the savings from cane harvest and transportation, as
well as sales revenue (income). The cost savings from cane
harvest and transportation were the result of some chemical
ripener treatments reducing cane yield. The cost of har-
vesting and transporting cane was set at USD 4.5 ha
-1
.
Chemical and spraying costs were combined to determine
the ripening cost. Chemical ripener costs were USD 30.0,
23.0, and 33.3 ha
-1
, respectively, for 2-chloroethylphos-
phonic acid, fluazifop-p-butyl, and trinexapac-ethyl,
respectively. The cost of spraying (including labor) with a
drone was estimated to be USD 5.62 ha
-1
. Sucrose selling
price was fixed at USD 0.62 kg
-1
.
The net benefit (NB) was computed by deducting the
total variable expenses (total cost of ripening) from the
gross field benefit for each treatment. The marginal rate of
return (MRR) was computed by dividing the difference
between the treatment’s net benefit and the control’s net
benefit by the variable cost of the treatment (cost of
ripening). The MRR of a ripener treatment must be
between 50 and 100% for it to be considered a viable
choice for sugarcane plantation (CIMMYT 1988). For each
treatment, residuals were produced to verify the marginal
analysis results. The residuals were calculated using the
difference between the net benefits achieved and the cost of
investment.
Results and Discussion
Stalk Height and Weight
The analysis of variance indicated that stalk height and
weight were influenced by the main effect of cultivar and
ripener. However, there was no significant cultivar x rip-
ener interaction (Table 1). Cultivar SP70-1284 had the
tallest stalk (1.76 m), while there was no significant dif-
ference among NCo334, B52-298 and C86-12 (Table 2).
The variation noted among the tested sugarcane cultivars
might be due to their genetic differences (Habib et al.
1991). Abo El-Hamd et al. (2013) also reported the absence
of cultivar 9ripener interaction in stalk height. In contrast,
Orgeron (2012) reported the presence of cultivar 9ripener
interaction in stalk height.
In relation to the ripener treatments, the control (un-
sprayed) had the tallest stalks and was similar to the
2-chloroethylphosphonic acid treatment. In contrast, the
other treatments all reduced stalk height when compared
with the control. Stalk height was reduced by 12, 11, 11
and 10% by the fluazifop-p-butyl, trinexapac-ethyl,
2-chloroethylphosphonic acid ?fluazifop-p-butyl sequen-
tial application, and trinexapac-ethyl ?fluazifop-p-butyl
sequential application treatments, respectively (Table 2).
The production of ethylene by 2-chloroethylphosphonic
acid diminishes the size and bulk of leaf canopy, which
reduces the growth sink demand for sucrose (Eastwood and
Davis 1997). The findings of the current study are consis-
tent with prior research which found that
2-chloroethylphosphonic acid did not reduce sugarcane
stalk height (Rostron 1985; van Heerden et al. 2015). A
decline in stalk growth due to the shortening of one or two
internodes may occur, although it has been shown to be
transient (Rostron 1985). On the other hand, treatment with
2-chloroethylphosphonic acid resulted in a significant drop
in stalk height (Abo El-Hamd et al. 2013).
The reduction in stalk height due to fluazifop-p-butyl
treatment resulted from the transfer of the active ingredient
to the stalk apical meristem where it terminates stalk
growth (Eastwood and Davis 1997; Rostron 1985) and
limits the growth of leaves (Rostron 1985). According to
Abo El-Hamd et al. (2013), fluazifop-p-butyl treatment
reduced stalk height regardless of application rates. The
effects of fluazifop-p-butyl, when used at ripener applica-
tion rates, are slow-acting and do not interfere with pho-
tosynthesis directly, allowing sucrose accumulation to
continue even after stalk growth stops (Petrasovits et al.
2013).
Similarly, the reduction in stalk height caused by
trinexapac-ethyl treatment was the result of reduced
internode elongation caused by an inhibition of the gib-
berellic acid GA
20
to GA
1
conversion pathway within the
sugarcane stalk (Resende et al. 2000; Rixon et al. 2007; van
Heerden et al. 2015). Similarly, Orgeron (2012) found that
a 350 g ai ha
-1
application rate of trinexapac-ethyl resul-
ted in a considerable reduction in stalk height. Trinexapac-
ethyl at rates of 200, 250, and 500 g ai ha
-1
resulted in a
quick and near-complete restriction of stalk growth up to
180 Sugar Tech (Jan-Feb 2023) 25(1):177–184
123
56 days following its application (van Heerden et al. 2015).
The application rate, on the other hand, determined sub-
sequent re-growth.
Compared to the control treatment, the sequential
application of 2-chloroethylphosphonic acid ?fluazifop-
p-butyl and trinexapac-ethyl ?fluazifop-p-butyl both
reduced stalk height, albeit their effects were not different
(Table 2). Due to the differential effect of the separate
ripeners on stalk height (Sweet et al. 1987), the reduction in
stalk height from the 2-chloroethylphosphonic acid ?flu-
azifop-p-butyl sequential application treatment was mostly
caused by fluazifop-p-butyl due to cessation of the stalk
apical meristem (Eastwood and Davis 1997).
A reduction in stalk height from the sequential appli-
cation of 2-chloroethylphosphonic acid and fluazifop-p-
butyl was also reported by Abo El-Hamd et al. (2013). In a
similar manner, the reduction in stalk height from the
trinexapac-ethyl ?fluazifop-p-butyl sequential application
was due to the synergistic effect of both ripeners on stalk
elongation (Eastwood and Davis 1997; Resende et al. 2000;
van Heerden et al. 2015).
The cultivar NCo334 had the lowest stalk weight
(0.95 kg) (Table 2). The difference among the tested sug-
arcane cultivars might be due to their innate genetic dif-
ferences. Similarly, Orgeron (2012) also reported
differences in stalk weight among sugarcane cultivars.
Stalk weight in the control treatment was similar to
2-chloroethylphosphonic acid treatment. Stalk weight in
the 2-chloroethylphosphonic acid treatment, in turn, was
greater than stalk weights in the fluazifop-p-butyl and
sequential application of trinexapac-ethyl ?fluazifop-p-
butyl treatments (Table 2). However, stalk weight in the
2-chloroethylphosphonic acid treatment was not signifi-
cantly different from the trinexapac-ethyl and the sequen-
tial application of 2-chloroethylphosphonic
acid ?fluazifop-p-butyl (Table 2).
It is important to highlight the fact that the lack of
influence of 2-chloroethylphosphonic acid on stalk weight
Table 1 Analysis of variance (pvalues) for yield components and yield in a field experiment involving four sugarcane varieties and five
chemical ripeners along with the control (unsprayed)
Source of variation Stalk height (m) Mean stalk weight (kg) Cane yield (t ha
-1
) Sucrose content (%) Sucrose yield (t ha
-1
)
Variety (V)
a
0.001 0.001 0.001 0.001 0.003
Ripener (R)
b
0.001 0.001 0.311 0.001 0.007
Variety 9ripener 0.831 0.994 0.978 0.550 0.781
a
Cultivars: B52-298, NCo334, C86-12, and SP70-1284
b
Ripener treatments: 2-chloroethylphosphonic acid, fluazifop-p-butyl, trinexapac-ethyl, 2-chloroethylphosphonic acid ?fluazifop-p-butyl
sequential application, trinexapac-ethyl ?fluazifop-p-butyl sequential application, and control (unsprayed)
Table 2 Main effects of variety and ripener treatments on stalk height, stalk weight, stalk diameter, number of internodes, and number of
millable stalks
Factor Stalk height (m) Stalk
a
weight (kg) Cane yield (t ha
-1
) Sucrose content (%) Sucrose yield (t ha
-1
)
Cultivar
B52-298 1.60 b 1.34 a 98.11 a 9.22 c 9.04 bc
NCo334 1.62 b 0.95 b 94.61 a 9.35 c 8.83 c
C86-12 1.55 b 1.34 a 84.84 b 11.69 a 9.92 ab
SP70-1284 1.76 a 1.31 a 94.92 a 10.78 b 10.19 a
Ripener
2-chloroethylphosphonic acid (E) 1.74 ab 1.29 ab 95.26 9.92 b 9.39 ab
Fluazifop-p-butyl (FF) 1.56 c 1.18 c 89.99 10.42 b 9.34 ab
Trinexapac-ethyl (M) 1.57 c 1.22 bc 91.22 10.53 b 9.56 ab
E?FF 1.58 c 1.20 bc 92.11 10.52 b 9.67 ab
M?FF 1.59 bc 1.17 c 93.23 11.39 a 10.58 a
Control (unsprayed) 1.77 a 1.33 a 96.89 8.75 c 8.43 b
CV (%) 7.96 7.11 8.65 6.47 10.76
a
Means were back-transformed for presentation. Means followed by the same letter or no letter in column are not significantly different from
each other according to Tukey’s HSD (0.05). Fluazifop-p-butyl was applied 38 days after 2-chloroethylphosphonic acid and 28 days after
trinexapac-ethyl
Sugar Tech (Jan-Feb 2023) 25(1):177–184 181
123
was a reflection of its lack of influence on stalk length. The
same holds true for the significant reduction in stalk weight
in the fluazifop-p-butyl, trinexapac-ethyl,
2-chloroethylphosphonic acid ?fluazifop-p-butyl sequen-
tial application and trinexapac-ethyl ?fluazifop-p-butyl
sequential application treatments. This is explained by the
fact that stalk elongation is positively correlated with stalk
weight (Silva et al. 2008).
Cane Yield, Sucrose Content and Sucrose Yield
Cane yield was affected only by the main effect of cultivar
(Table 1). The highest cane yield (98.11 t ha
-1
) was
recorded in cultivar B52-298, which was similar to the
cane yields in cultivars NCo334 and SP70-1284, while
cultivar C86-12 had lowest cane yield (84.84 t ha
-1
)
(Table 2). The difference between the tested cultivars in
cane yield might be attributed to their genetic makeup
(Abo El-Hamd et al. 2013).
Although all the chemical ripener treatments, except for
2-chloroethylphosphonic acid, reduced stalk height and
weight although this did not translate into reductions in
cane yield. The lack of significant effects on cane yield
among the ripener treatments could be due to increase in
stalk mass (effective ripening), as evidenced by the
increase in sucrose content induced by the various ripener
treatments, as well as the study’s relatively short spray-to-
harvest intervals (van Heerden 2013) and lower chemical
rates (Abo El-Hamd et al. 2013).
Similarly, other authors also reported the absence of
significant cane yield reduction due to treatment with flu-
azifop-p-butyl (van Heerden 2013) and trinexapac-ethyl
(Kingston and Rixon 2007; Resende et al. 2000). Contrary
to this, Abo El-Hamd et al. (2013) reported a significant
cane yield reduction due to treatment with fluazifop-p-
butyl. Similarly, Orgeron (2012) reported a significant
reduction of cane yield due to treatment with trinexapac-
ethyl applied at 300 and 350 g ai ha
-1
.
Sucrose content (%) was affected only by the main
effects of cultivar and ripener (Table 1). Cultivar C86-12
had the highest sucrose content (11.69%) followed by
SP70-1284, which in turn had higher sucrose content than
NCo334 and B52-298 (Table 2).
The trinexapac-ethyl ?fluazifop-p-butyl sequential
application treatment resulted in the highest sucrose con-
tent of all treatments, whereas the control had the lowest
sucrose content (Table 2). Compared to the control treat-
ment, the sucrose content due to the application of
2-chloroethylphosphonic acid, fluazifop-p-butyl, trinexa-
pac-ethyl, 2-chloroethylphosphonic acid ?fluazifop-p-
butyl sequential application and trinexapac-ethyl ?fluaz-
ifop-p-butyl sequential application increased by 1.18, 1.68,
1.79, 1.78 and 2.65% units, respectively (Table 2).
The increase in sucrose content in the ripener treatments
was due to the reduced growth sink demand, which ulti-
mately led to the accelerated accumulation of sucrose in
the stalk (Resende et al. 2000; Rixon et al. 2007). Similar
to this study, earlier research also confirmed increase in
sucrose content due to treatment with 2-chloroethylphos-
phonic acid (Abo El-Hamd et al. 2013), fluazifop-p-butyl
(Abo El-Hamd et al. 2013; van Heerden 2019) and
trinexapac-ethyl (Kingston and Rixon 2007; Resende et al.
2000). Similarly, other studies also reported the synergistic
and additive effect of 2-chloroethylphosphonic
acid ?fluazifop-p-butyl sequential application (Rostron
1985; Sweet et al. 1987) and trinexapac-ethyl ?fluazifop-
p-butyl sequential application (van Heerden 2013)in
increasing sucrose content.
Analogous to sucrose content, sucrose yield (t ha
-1
) was
also significantly influenced by the main effects of cultivar
and ripener (Table 1). Among the cultivars, SP70-1284 had
the highest sucrose yield (10.19 t ha
-1
), which was similar
to C86-12; however, NCo334 recorded the lowest sucrose
yield (Table 2). Among the ripener treatments, trinexapac-
ethyl ?fluazifop-p-butyl sequential application resulted in
the highest sucrose yield (10.58 t ha
-1
) and was the only
treatment that differed significantly from the control
(Table 2).
The large increase in sucrose content that exceeded all
other treatments and the lack of any negative effect on cane
yield explains the very large positive sucrose yield
response achieved from the sequential application of
trinexapac-ethyl ?fluazifop-p-butyl. Consistent with the
current finding, van Heerden (2013) also reported the
synergistic effect of trinexapac-ethyl ?fluazifop-p-butyl
sequential application in increasing sucrose yield.
Economic Analysis
The trinexapac-ethyl ?fluazifop-p-butyl sequential appli-
cation treatment yielded the highest net benefit of USD
5839.93 ha
-1
followed by the 2-chloroethylphosphonic
acid ?fluazifop-p-butyl sequential application treatment
(USD 5328.24 ha
-1
), trinexapac-ethyl (USD
5292.42 ha
-1
), fluazifop-p-butyl (USD 5205.26 ha
-1
),
2-chloroethylphosphonic acid (USD 5168.22 ha
-1
), and
control (USD 4678.71 ha
-1
) treatments, respectively
(Table 3).
Regarding the marginal rate of return, the highest value
of 5509% was obtained from the sole treatment fluazifop-
p-butyl, while the lowest was obtained from the sole
2-chloroethylphosphonic acid treatment (967%). This
variation in marginal return value was due to the lower cost
of ripening in the sole treatment fluazifop-p-butyl
(Table 3).
182 Sugar Tech (Jan-Feb 2023) 25(1):177–184
123
However, in marginal analysis, the marginal rate of
return is not the final criterion for recommendation since it
does not account for the returns on investment (residuals).
The maximum return on investment was obtained from the
trinexapac-ethyl ?fluazifop-p-butyl sequential application
treatment (USD 5791.41 ha
-1
). Therefore, the most eco-
nomical option among the ripener treatments was derived
from the trinexapac-ethyl ?fluazifop-p-butyl sequential
application with a marginal rate of return of 2393%
(Table 3). In all the ripener treatments, a marginal rate of
return greater than 1 was obtained compared to the control
(unsprayed) (Table 3), which is greater than the minimum
requirement.
Conclusions
The results presented in this study clearly showed the high
level of effectiveness of chemical ripeners in increasing
sucrose content and sucrose yield at Kessem sugarcane
plantation. Overall, ripeners consistently increased sucrose
yield. All the studied sugarcane cultivars responded posi-
tively, with sucrose content increases of more than 1% unit
compared to the control treatment in all the ripener treat-
ments. However, the trinexapac-ethyl ?fluazifop-p-butyl
sequential application was found to be the best ripener
treatment to increase sucrose yield of sugarcane cultivars
B52-298, NCo334, C86-12 and SP70-1284. Furthermore,
in economic terms, the trinexapac-ethyl ?fluazifop-p-
butyl sequential application treatment was found to be the
best option. Therefore, it is advisable to evaluate these
experimental results at a commercial level during the mid-
period of sugarcane crushing on immature crops cultivated
at sugarcane plantations in Ethiopia.
Acknowledgments Special thanks go to Ethiopian Sugar Corpora-
tion for funding this research work. Special thanks are also extended
to the management and technical team staff of Kessem Research
Station and Kessem Sugar Estate for their collaboration and provision
of assistance in every aspect.
Funding This study was funded by Ethiopian Sugar Corporation.
Declarations
Conflict of Interest The authors declare that they have no conflict of
interest.
References
Abo El-Hamd, A.S., M.A. Bakheet, and A.F.I. Gadalla. 2013. Effect
of chemical ripeners on juice quality, yield and yield compo-
nents of some sugarcane cultivars under the conditions of Sohag
Governorate. American-Eurasian Journal of Agricultural &
Environmental Sciences 13 (11): 1458–1464. https://doi.org/
10.5829/idosi.aejaes.2013.13.11.11261.
Ayele, N., S. Tegene, T. Negi, A. Getaneh, L. Mengistu, Y.
Mequannent, and D. Z. Dilnesaw. 2016. Challenges of ripening
of sugarcane at Tendaho, Metahara and Wonji-Shoa sugar
estates. European Journal of Food Science and Technology 4(4):
22–30. https://www.eajournals.org/journals/european-journal-of-
food-science-and-technology-ejfst/vol-4-issue-4-september-
2016/challenges-ripening-sugarcane-tendaho-metahara-wonji-
shoa-sugar-estates/
Berg, V. 1972. Control of the cane sugar manufacture. Manual for
sugar chemist course of H.V.A. Wonji-Shoa Sugar Factory,
Ethiopia.
Bharati, B., R. Panta, and K. Khanal. 2018. Assessing socio-economic
condition of sugarcane producers in Nawalparasi district of
Table 3 Partial budget analysis for sucrose yield from the five ripener treatments for the experiment conducted at Kessem sugar estate
Parameters Ripener treatments
Control 2-Chloroethyl-phosphonic
acid
Fluazifop-p-
butyl
Trinexapac-
ethyl
E?FF M ?FF
Actual sucrose yield (kg ha
-1
) 8430.0 9390.0 9340.0 9560.0 9670.0 10,580.0
Adjusted sucrose yield (kg ha
-1
) 7587.0 8451.0 8406.0 8604.0 8703.0 9522.0
Sales revenue from sucrose (USD ha
-1
) 4678.7 5211.5 5183.8 5305.9 5366.9 5872.0
Saving from HT (USD ha
-1
)
a
0.0 7.3 31.0 25.5 21.5 16.5
Gross field benefit (USD ha
-1
) 4678.7 5218.8 5214.8 5331.4 5388.4 5888.4
Cost of chemicals (USD ha
-1
) 0.0 45.0 3.9 33.3 48.9 37.3
Cost of spraying (USD ha
--1
) 0.0 5.6 5.6 5.6 11.25 11.2
Cost of ripening (costs that vary) (USD ha
-1
) 0.0 50.6 9.6 38.9 60.2 48.5
Net benefit (USD ha
-1
) 4678.7 5168.2 5205.3 5292.4 5328.2 5839.9
Marginal rate of return (%) – 967 5509 1575 1079 2393
Return on investment (residuals) (USD ha
-1
) 4678.7 5117.6 5195.7 5253.5 5268.1 5791.4
E denotes 2-chloroethylphosphonic acid, FF denotes fluazifop-p-butyl, M denotes trinexapac-ethyl
a
HT = harvest and transport
Sugar Tech (Jan-Feb 2023) 25(1):177–184 183
123
Western Nepal. Biomedical Journal of Scientific & Technical
Research 12 (3): 9296–9297. https://doi.org/10.26717/BJST
R.2018.12.002264.
Cardozo, N.P., and P.C. Sentelhas. 2013. Climatic effects on
sugarcane ripening under the influence of cultivars and crop
age (Review). Scientia Agricola 70 (6): 449–456.
https://doi.org/10.1590/S0103-90162013000600011.
CIMMYT. 1988. From agronomic data to farmer recommendations:
An economics training manual completely revised edition.
Mexico, DF.
Eastwood, D., and H.D. Davis. 1997. Chemical ripening in Guyana—
Progress and prospects. Sugar Cane 3: 4–17.
Ebrahim, M.K., O. Zingsheim, M.N. El-Shourbagy, P.H. Moore, and
E. Komor. 1998. Growth and sugar storage in sugarcane grown
at temperatures below and above optimum. Journal of Plant
Physiology 153: 593–602. https://doi.org/10.1016/S0176-16
17(98)80209-5.
EIA (Ethiopian Investment Agency). 2012. Investment opportunity
profile for sugar cane plantation and processing in Ethiopia.
Ethiopian Investment Agency (EIA). http://ethemb.se/wp-con
tent/uploads/2013/07/Sugar-Cane-Plantation-and-Processing-in-
Ethiopia.pdf
Getaneh, A., and T. Negi. 2014. Effect of length of pre-harvest
drying-off period during the cool season on soil moisture content
and cane quality of sugarcane cultivars at Metahara Sugar Estate.
International Scholar Journal 2 (9): 211–218.
Gosnell, J.M., and J.E. Lonsdale. 1974. Some effects of drying off
before harvest on cane and yield quality. Proceedings of
International Society of Sugarcane Technologists 15:701–711.
http://www.issct.org/proceedings/1974.html
Habib, G., K.B. Malik, and M.Q. Chatha. 1991. Preliminary
evaluation of exotic sugarcane varieties for quantitative charac-
ters. Pakistan Journal of Agricultural Research 12: 95–101.
James, G. 2004. Sugarcane, 2nd ed., 187. Oxford: Blackwell Science
Ltd.
Kingston, G., and C.M. Rixon. 2007. Ripening responses of twelve
sugarcane cultivars to Moddus (trinexapac-ethyl). Proceedings
of the Australian Society of Sugar Cane Technologists 29:
328–338.
Lakshmanan, P., R.J. Geijskes, K.S. Aitken, C.L.P. Grof, G.D.
Bonnett, and G.R. Smith. 2005. Sugarcane biotechnology: The
challenges and opportunities. In Vitro Cellular & Developmental
Biology-Plant 41: 345–363.
Li, Y.R., and S. Solomon. 2003. Ethephon: a versatile growth
regulator for sugar cane industry. Sugar Tech 5: 213–223.
https://doi.org/10.1007/BF02942476.
Orgeron, A.J. 2012. Sugarcane growth, sucrose content, and yield
response to the ripeners glyphosate and trinexapac-ethyl. LSU
Doctoral Dissertations. 1362. https://digitalcommons.lsu.
edu/gradschool_dissertations/1362
Petrasovits, L.A., R.B. McQualter, L.K. Gebbie, D.M. Blackman,
L.K. Nielsen, and S.M. Brumbley. 2013. Chemical inhibition of
acetyl coenzyme A carboxylase as a strategy to increase
polyhydroxybutyrate yields in transgenic sugarcane. Plant
Biotechnology Journal 11: 1146–1151.
Resende, P.A.P., J.E. Soares, and M. Hudetz. 2000. Moddus, a plant
growth regulator and management tool for sugarcane in Brazil.
Sugar Cane International 4: 5–9. https://www.cabdirect.org/cab
direct/abstract/20016785792
Rixon, C.M., L.P. Di Bella, G. Kingston, K. Dorahy, B. Davies, and
A.W. Wood. 2007. Moddus
Ò
a sugar enhancer. Proceedings of
the Australian Society of Sugar Cane Technologists 29:
318–327.
Robertson, M.J., R.C. Muchow, R.A. Donaldson, N.G. Inman-
Bamber, and A.W. Wood. 1999. Estimating the risk associated
with drying-off strategies for irrigated sugarcane before harvest.
Australian Journal of Agricultural Research 50: 65–77.
https://doi.org/10.1071/A98051.
Rostron, H. 1985. Chemical ripening of sugarcane with Fusilade
Super. Proceedings of the South African Sugar Cane Technol-
ogists Association 59: 168–175.
Rostron, H. 1996. Chemical ripening of sugarcane in Swaziland. In
Sugarcane: Research towards efficient and sustainable produc-
tion, ed. J.R. Wilson, D.M. Hogarth, J.A. Campbell, and A.L.
Garside, 172–175. Brisbane: CSIRO, Division of Tropical Crops
and Pastures.
Sachdeva, M., S. Bhatia, and S.K. Batta. 2011. Sucrose accumulation
in sugarcane: A potential target for crop improvement. Acta
Physiologiae Plantarum 33: 1571–1583.
SAS Institute. 2009. The statistical analysis software system for
windows. Version 9.2. Cary: SAS institute INC.
Silva, M.A., J.A.G. Silva, J. Enciso, V. Sharma, and J. Jifon. 2008.
Yield components as indicators of drought tolerance of sugar-
cane. Scientia Agricola 65 (6): 620–627. https://doi.org/10.159
0/S0103-90162008000600008.
Singels, A., A.J. Kennedy, and C.N. Bezuidenhout. 2000. The effect
of water stress on sugarcane biomass. Proceedings of the South
African Sugar Cane Technologists Association 74: 169–172.
Spaunhorst, D.J., J.R. Todd, and A.L. Hale. 2019. Sugarcane cultivar
response to glyphosate and trinexapac-ethyl ripeners in Louisi-
ana. PLoS ONE 14 (6): e0218656. https://doi.org/10.1371/jou
rnal.pone.0218656.
Sweet, C.P.M., P.W. White, and G.H. Dodsworth. 1987. Commercial
experience with chemical sugarcane ripeners at Simunye sugar
estate in Swaziland. Proceedings of the South African Sugar
Cane Technologists Association 61: 121–127.
https://pdfs.semanticscholar.org/98b6/
7c6a85e60ea38e2577effba8fd7076fc70d7.pdf
van Heerden, P.D.R. 2013. Evaluation of Trinexapac-ethyl (Moddus)
as a new chemical ripener for the South African sugarcane
industry. Sugar Tech 16 (3): 295–299. https://doi.org/10.1007/
s12355-013-0278-x.
van Heerden, P.D.R. 2019. Response of selected South African
coastal sugarcane cultivars to chemical ripeners: Active ingre-
dient effectiveness and associated impacts on grower and miller
sustainability. Proceedings of South African Sugar Cane Tech-
nologists Association 92: 18–21.
van Heerden, P.D.R., G. Eggleston, and R.A. Donaldson. 2014.
Ripening and post-harvest deterioration. In Sugarcane physiol-
ogy, biochemistry and functional biology, ed. F.C. Botha and
P.H. Moore, 55–84. New York: Wiley-Blackwell.
van Heerden, P.D.R., T.P. Mbatha, and S. Ngxaliwe. 2015. Chemical
ripening of sugarcane with trinexapac-ethyl (Moddus)—Mode of
action and comparative efficacy. Field Crops Research 181:
69–75. https://doi.org/10.1016/j.fcr.2015.06.013.
Yamori, W., K. Noguchi, and I. Terashima. 2005. Temperature
acclimation of photosynthesis in spinach leaves: Analyses of
photosynthetic components and temperature dependencies of
photosynthetic partial reactions. Plant, Cell and Environment 28:
536–547.
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184 Sugar Tech (Jan-Feb 2023) 25(1):177–184
123
