IJERD – International Journal of Environmental and Rural Development (2014) 5-1

Research article
erdChanges in Cassava Yields with Trimmed Leaves forEri-culture in Kampong Cham Province, Cambodia
KUMIKO KAWABE*
Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, Japan /Research Center, Institute of Environment Rehabilitation and Conservation, Tokyo, Japan
Email: kumiko@khmergreennature.com

MACHITO MIHARA
Faculty of Regional Envrionment Science, Tokyo University of Agriculture, Tokyo, Japan

KEISHIRO ITAGAKI
Faculty of Internationl Agriculture and Food Stuides, Tokyo University of Agriculture, Tokyo,Japan
Received 26 December 2012

Accepted 20 March 2014(*Corresponding Author)

Abstract Cassava (Manihot esculenta), a host plant of eri silkworm (Samia Cynthia ricini),
is one of the main crops, followed by rice in Cambodia. As it was not long ago that ericulture was introduced in Cambodia, the research related to eri-culture and eri silkworms
in Cambodia has not been developed. Especially, trimming methods of cassava leaves
have not been studied yet. Accordingly, attention has been paid to evaluate the suitableamounts of leaves trimmed for eri-culture without affecting cassava tuber yields. So, thisstudy dealt with the potential percentage of cassava leaves trimmed for eri-culture inCambodia. In the experimental field at Royal University of Agriculture located in Phnom
Penh, cassava, variety called KM 94, was cultivated from November 2011 to July 2012 for
8 months. After 4 months passed from planting, the leaves were trimmed at 0%, 20%, 40%,60%, 80% and 100%, respectively. At 8 months passed from planting, the yields werecompared amongst plots of different trimmed percentage, and the suitable amounts ofleaves trimmed for eri-culture without affecting cassava tuber yields were discussed. The
experimental results showed that yields of 100% trimmed were significantly smaller thanthat of 0% to 80% trimmed. Additionally, there was no significant difference in yields
amongst plots trimmed 0% to 80%. It was concluded that cassava leaves can be trimmed
up to 80% without affecting cassava tuber yields.
Keywords eri-culture, eri silkworm, cassava, trimmed leaves

INTRODUCTION
Eri-culture, raising eri silkworms (Samia Cynthia ricini), has been conducting widely in Southeast
Asia, such as southern China, Thailand, Vietnam and Cambodia. Although its origin is Assamprovince in India, eri silkworm became the only one kind among various wild silkworms whichdomesticated in the same manner of mulberry silkworm and it has introduced to many countries
where host plant of eri silkworm can be found or cultivated (Photo. 1). Host plants of eri silkworm
are the leaves of castor, cassava or papaya which are very easy to cultivate in the tropical or subtropical areas. The most attractive points of eri-culture for local farmers are that eri-culture can startwith low input, for example the leave of cassava or castor is costless and rearing materials such asbamboo tray or net are easy to find in local areas, and eri-culture can provide local farmers not only
cocoons but also pupae that includes high nutrition of protein.
Eri-culture has introduced in local villages of Kampong Cham province, Cambodia in October2010 by the international NGO for aiming to promote environmental awareness and income
generation for local farmers to tackle with local problems regarding agriculture.
Agriculture is the main industry in Cambodia, and the statistics shows that 80% of totalⒸ ISERD

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population lives in rural areas and 70% of total population is engage in agriculture or related
sectors (Central Intelligence Agency, 2011). The government places the first priority on agriculture,
but at the same time it is very important for local people to sustain their living. However, local
farmers in Cambodia still have difficulties to earn enough income from agriculture due to lack ofinfrastructure, knowledge, technology and information.
Cassava is one of the main crops followed by rice in Cambodia, and its yields has been
increasing according to the statistics of FAO as shown in Fig. 1, due to the high potential of foodsecurity. In the research area, Kampong Cham province, the harvesting areas and yields of cassava
have been increasing dynamically in recent years. Normally cassava farmers get income from tuber
yields; however there may be high possibility to receive other income by using cassava leaves. So,
eri-culture can be one of the options to utilize the leaves, and it can be useful for local farmers togenerate more income from agriculture.

Photo
1. Eri-silkworms
Photo.
1 Cultivating
eri-silkworms
10,000,000

Amount of production (Mt)

9,000,000
8,000,000
7,000,000
6,000,000
Rice
5,000,000

Cassava

4,000,000

Maize

3,000,000
2,000,000

1,000,000
02000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

YearSource: FAO stat (2011)

Fig. 1 Trend of production in Cambodian top 3 crops
OBJECTIVE
The objective of this paper is to evaluate the suitable percentage of cassava leaves trimmed in midflow of cultivating without any effects on tuber yields of cassava in the research site. One of themain obstacles for local farmers to continue eri-culture was to gain enough amounts of fresh leaves
for rearing eri silkworms during dry season. A host plant of eri silkworm, cassava leaf, has rarely
been used after harvesting tubers in Cambodia. So, attention has been paid to the effect on cassava
yields after trimming certain amounts of leaves during its growing period. As the appropriateⒸ ISERD

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trimming methods have not yet been studied, the methods for eri-culture are also discussed in thisstudy. It is expected that the results would be available to extend the utilization of cassava leaves
for eri-culture in Cambodia.
METHODOLOGYThis experiment was conducted at the experimental field in the Royal University of Agriculture(RUA) located in Phnom Penh, Cambodia (Photo. 2). The variety of cassava named KM 94 waschosen for the experiment, as the variety has been widely cultivated by local farmers in Kampong
Cham province. Each experimental plot was a 4 m x 4 m square at 30 cm of planting interval as
shown in Fig. 2. There were 20 cassava trees in each of the 15 plots, so totally 300 cassava trees
were planted and cultivated from November 2011. Numbering of the plots was done from thesouthwestern plot along west side as “a1” to “a5”, from the southern plot to north for the middle
lane as “b1” to “b5”, and from the southeastern plot along east side as “c1 to c5”.
Ensuring the growing conditions in each plot, all cassava trees were measured by height after
4 months of planting, and 48 cassavas in 6 plots with no significant difference in height were used
for the further experiment (meshed plots in Fig. 2). Trimmed percentage was decided for each plot,“c5” for 0%, “c4” for 20%, “c1” for 40%, “b5” for 60%, “b1” for 80% and “a2” for 100%,
respectively (Fig. 3). Also, meteorological conditions, such as temperature, humidity and rainfall,
were observed at the experiment field in the Royal University of Agriculture during theexperimental period.

Photo. 2 Experimental field at Royal
University of Agriculture

0％ Trimmed

20％ Trimmed

171819201718192017181920131415161314151613141516910a511

12910b51112910c5 1112567856785678123412341234171819201718192017181920131415161314151613141516910a411

12910b4 1112910c411

125678567856781234123412341718192017181920171819201314910515161314151613141516a311

12910b311

12910c3 1112678567856781234123412341718

1920

1718

1920

1718

19201314

910515161314151613141516a211

12910b211

12910c2 11126785678

5678

12341234

12341718

19201718

19201718

19201314

91051151613

14151613

1415

16

a111

12910b111

12910c111

12678567856782341234

1234Fig. 2 Experimental plots at RUA,Cambodia

40％ Trimmed

60％ Trimmed

80％ Trimmed

Fig. 3 Trimming methods from 0% to 100%
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100％ Trimmed

IJERD – International Journal of Environmental and Rural Development (2014) 5-1

RESULTS AND DISCUSSION
Meteorological Data Observed during the Experiment
Meteorological conditions were observed from July 2010 to July 2012 at the experimental site inRoyal University of Agriculture, Cambodia. The observed period covered whole the experimental
period from November 2011 to July 2012. During the experimental period from November 2011 toJuly 2012, higher and lower temperature ranged from 30 degree Celsius to 37 degree Celsius andfrom 20 degree Celsius to 26 degree Celsius, respectively. Also, the monthly rainfall was from 0mm to 190 mm. The trends of temperature and humidity from November 2011 to July 2012 weresimilar with that from November 2010 to July 2011. However, there was less rainfall fromDecember 2011 to February 2012 comparing to that from December 2010 to February 2011 asshown in Fig. 4.
(mm / month)(°C) / %120

400350

100
300
80
250

Rainfall (mm)Highest temperature (°C)

60200
150

Lowest temperature (°C)
Highest humidity (%)

Lowest humidity (%)

40100
205000JulAug Sep

Oct Nov Dec

JanFeb Mar Apr May Jun

2010JulAug Sep

Oct Nov Dec

JanFeb Mar Apr May Jun

Jul20122011

Experimental period

Fig. 4 Meteorological conditions observed at experimental field from July 2010 to July 2012
Table 1 Height of selected cassava trees in each plot
Name of plot

Height of each cassava tree(cm)

Average

c593
109
110
93
105
113
103.8

c486
94
113
102
99
113
95
105
100.9

c199
102
108
103
101
101
90
102
100.8

b590
100
94
91
93
105
105
100
97.3

b1107
96
101
9089101998896.4

a294
112
94
10498
96
97
91
98.3

Selection of Cassava for Trimming
In March 2012, after 4 months passed from planting, the heights of 300 cassava trees weremeasured. Eight plants in each of selected 6 plots which indicated no significant difference inheight were selected for further experiment (Table 1). This is to ensure that selected cassava trees
grew similarly although there were various factors affecting to the growth of cassava trees such as
soil nutrients, moisture, solar radiations, and other plants effects, so on.
And then, amounts of cassava leaves from the lower part were trimmed at 0%, 20%, 40%,60%, 80% and 100% (Fig. 3) in March 2012. The plot was selected as “c5” for 0%, “c4” for 20%,“c1” for 40%, “b5” for 60%, “b1” for 80% and “a2” for 100%, respectively (Fig. 2).

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Changes in Cassava Yields with Trimmed Leaves
The leaves of selected cassava were trimmed at 0% (c5 plot), 20% (c4 plot), 40% (c1 plot), 60%(b5 plot), 80% (b1plot) and 100% (a2 plot), respectively (Fig. 3). After 4 months passed, cassava
tubers were harvested and the mass of tubers in each cassava tree was measured in July 2012.
The experimental results were summarized in Fig. 5. It showed that the yield of 100%
trimmed leaves was significantly smaller than that of 0% to 80% trimmed. Also, there was no
significant difference in the yield among plots trimmed 0% to 80%. It was considered that trimmed
cassava trees at 0% to 80% could recover the function of photosynthesis with reproducing cassava
leaves. However, photosynthesis was not enough to grow cassava tubers for cassava trees trimmed
at 100%.
Also, the fresh mass of trimmed cassava leaves at 0% to 80% was measured for cultivating
eri-silkworms at middle flow of harvesting cassava as shown in Table 2. Apparently, there was atendency for the fresh mass of trimmed cassava leaves to be larger with the increase in percentage
trimmed. It indicated that 202.42 g of fresh cassava leaves were harvested from one cassava plantof 80% trimmed for cultivating eri-silkworms.
A**5
Mass of harvested cassava tubers (kg)

A**

4.5

A**
A**

43.5

A**

32.521.5
B**

10.50
c50%

c4
20%

c140%

b560%

b180%

a2
100% trimmed

Different letter indicates the significant difference at 99%(**) .

Fig. 5 Effects of trimmed amounts of cassava leaves on mass of harvested cassava tubers
Table 2 Fresh mass of selected cassava leaves in each plot from 0% to 80% trimmed
Name of plot

Fresh mass ofcassava
leavestrimmed (g)Average (g)c5(0% trimmed)
0000000c4(20% trimmed)
42.72
28.98
35.39
13.92
45.58
23.25
17.63
34.09
30.20

c1(40% trimmed)
90.90
55.80
62.88
106.92
84.99
92.51
81.69
111.8985.95

b5(60% trimmed)
137.41281.20169.51
159.1979.81
191.71160.84145.82165.69b1(80% trimmed)
232.74185.21290.75129.42163.67220.66220.49176.44202.42

CONCLUSION
Cassava (Manihot esculenta), a host plant of eri silkworm (Samia Cynthia ricini), is one of themain crops in Cambodia, and its harvested areas and yields have been increasing in the last fiveyears and it is estimated to expand year by year.
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Eri-culture, the raising of eri silkworm, a kind of wild silkworm originated in Assam province,
India, was introduced to Cambodia in October 2010. Since then, farmers face the difficulty toensure fresh leaves for feeding eri silkworm. So trimming methods of leaves should be studied.
Accordingly, attention has been paid to evaluate the suitable amounts of leaves trimmed for ericulture without damaging cassava yields.
KM 94, one of cassava variety that is widely adopted by local farmers in Cambodia, wascultivated from November 2011 to July 2012, a period of 8 months, at the experimental field inRoyal University of Agriculture located in Phnom Penh. After 4 months passed from planting, theleaves were trimmed at 0%, 20%, 40%, 60%, 80% and 100%, respectively. At 8 months passed
from planting, the yields were compared among plots of different trimming percentage anddiscussed the suitable amounts of leaves trimmed for eri-culture without damaging cassava tubers.
The results showed that the yields of 100% trimmed were significantly smaller than that of 0% to80% trimmed. Moreover, there was no significant difference in yields amongst plots trimmed 0%to 80%. Accordingly, it was concluded that cassava leaves can be trimmed up to 80% without
damaging cassava yields.
ACKNOWLEDGEMENTS
I would like to express our gratitude to Dr. Bunthan NGO, Rector at Royal University ofAgriculture to rent us the experimental farm of the university. I also would like to thank EREON
Cambodia Branch for the assistance to provide at all levels of the research project.
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