Analysis of Factors Influencing the Production of Dried Gambier Sap

in Pakpak Bharat District

Tasya Chairuna Pane

and Tavi Supriana

Faculty of Agriculture, Universitas Islam Sumatera Utara, Medan, Sumatera Utara, Indonesia

Faculty of Agriculture, Universitas Sumatera Utara, Medan, Sumatera Utara, Indonesia

Keywords: Gambier Leaf, Dried Gambier Sap, Production, Harvested, Processing Capacity.

Abstract: Gambier has high economic value, but it has not been cultivated intensively in Indonesia. Plant area and

production of gambier still fluctuate from year to year. Pakpak Bharat is the largest gambier-producing

region in North Sumatra. The factors that directly and indirectly influence the production of dried gambier

sap in Pakpak Bharat District were analyzed using the linear regression model with the intermediate or

intervening variable. The results showed that the area of productive plants, the use of fertilizers, and the

experience in farming had a positive and significant influence on the amount of harvested gambier leaf, the

types of seeds, and the use of pesticides. However, the age of productive plants have a negative and

significant influence. Meanwhile, the number of productive plants has a positive influence and the number

of cultivation labors has a negative influence, although it is not significant. The number of processing labors

has a positive and significant influence on the production of dried gambier sap; while the amount of

harvested gambier leaf has a positive but not significant influence. Variables influencing the amount of

harvested gambier leaf cannot influence the production of dried gambier sap indirectly through the

mediation of the amount of harvested gambier leaf.

1 INTRODUCTION

Dried gambier sap is the dried extract of boiled leaf

and twig of gambier plant (Uncaria gambier Roxb).

Gambier sap has many benefits and can be used both

in the traditional and modern industry, so the need

for gambier continues to increase. Consequently, it

has high economic value. Although Indonesia is a

large exporting country in the world gambier

market, gambier plantation is a smallholder

plantation and has not been cultivated intensively.

According to Manan (Manan, 2008), all gambier

plantations in Sumatera are smallholder plantations,

and no investors are trying to manage them.

According to Ermiati (Ermiati, 2004), the prospect

of high gambier demand has not been accompanied

by increased productivity, quality, and income of

farmers. Gambier industry is still classified as the

home industry, so the productivity, quality, and

income of farmers are still low.

Many problems must be faced in gambier

plantation development, ranging from cultivation

techniques, post-harvest processing, business

planning, marketing, to the socio-economic and

cultural aspects. According to Fauza et al. (Fauza et

al. 2007), the main problem in gambier plantation

development is low productivity. The low

productivity of gambier occurs due to the traditional

cultivation techniques, the use of non-optimal

production inputs, the unavailability of superior

varieties, inadequate maintenance, as well as the

methods and tools of harvesting and processing that

have not been effective and efficient.

The production centers of gambier in Indonesia

are still limited. Based on BPS-Statistics Indonesia

(BPS-Statistics Indonesia, 2014), the three largest

gambier producing regions in Sumatra are Lima

Puluh Kota District in West Sumatra Province and

followed by Pakpak Bharat District and Dairi

District in North Sumatra Province. The largest

gambier-producing region in Indonesia is Kabupaten

Lima Puluh Kota in West Sumatera Province.

Meanwhile, the area of plants and production of

gambier in North Sumatra, which is the second

largest gambier-producing region in Indonesia, still

fluctuates from year to year. It shows that gambier

farming in North Sumatra is potential to be

developed intensively. The largest gambier-

242

Pane, T. and Supriana, T.

Analysis of Factors Inﬂuencing the Production of Dried Gambier Sap in Pakpak Bharat District.

DOI: 10.5220/0008888102420249

In Proceedings of the 7th International Conference on Multidisciplinary Research (ICMR 2018) - , pages 242-249

ISBN: 978-989-758-437-4

producing region in North Sumatra is Pakpak

Bharat.

It is slow and fluctuating increase in production

and the demand in the domestic and world markets

continue to increase along with new studies about

the benefits of gambier. This situation leads to

increases gambier demand for industries. It makes

gambier farming potential to be developed

intensively. Based on this, this study aims to analyze

the factors that directly and indirectly influence the

production of dried gambier sap in Pakpak Bharat

District. Mediawati (2010) in Pakpak Bharat

District, North Sumatera Province, showed that the

factors influencing gambier production were the

number of cultivation labors, the use of fertilizers,

and the number of productive plants. Afrizal (2009)

in Lima Puluh Kota District, West Sumatera

Province, showed that the factors influencing

gambier production were the number of cultivation

labors, the area of productive plants, the use of

pesticides, the number of productive plants, the age

of productive plants, cultivation methods, farming

experience. Ermiati and Rosmeilisa (2001) in Harau

Sub-district, Lima Puluh Kota District, West

Sumatera Province, showed that the types of seeds,

the use of fertilizers, and the technology of

processing influence gambier production.

2 METHODS

The study was conducted in Pakpak Bharat District

because it was the largest gambier plant area and

production in North Sumatra Province. The

population of this study was the gambier farmers in

Pakpak Bharat District, who planted gambier started

from the cultivation to the processing into dried

gambier sap. The sampling was carried out using a

simple random sampling method. The samples

obtained from Sitellu Tali Urang Jehe, Pergetteng

Getteng Sengkut, Kerajaan, and Tinada Sub-districts

because they had the largest gambier farmer

population in Pakpak Bharat District with more than

100 gambier farmers. The data used were the

primary data obtained through interviews with 100

gambier farmers in 2013.

The collected data were then tabulated and

analyzed using the linear regression model with

intermediate or intervening variables. Model

estimation used Ordinary Least Square (OLS)

method. The data processing used the SPSS 24

Program. The production of dried gambier sap was

influenced by the amount of harvested gambier leaf

and the number of processing labors. While the

amount of harvested gambier leaf was influenced by

the cultivation labors, the area of productive plants,

the types of seeds, the use of fertilizers, the use of

pesticides, the number of productive plants, the age

of productive plants, and the experience in farming.

Therefore, through the amount of harvested gambier

leaf, the number of cultivation labors, the area of

productive plants, the types of seeds, the use of

fertilizers, the use of pesticides, the number of

productive plants, the age of productive plants, and

the experience in farming were expected to influence

the production of dried gambier sap. The path of

analysis of the influencing factors of the production

of dried gambier sap in Pakpak Bharat District was

presented in Figure 1.

Figure 1: Path of Analysis.

Model of the production of dried gambier sap in

this study is mathematically expressed in a multiple

linear regression equation as follow.

HPDG = c

+ c

TKB + c

LLTM + c

JB + c

PPu + c

PPe + c

TM + c

UTM + c

PB +

(1)

PGGK = b

+ b

HPDG + b

TKP + μ

(2)

Descriptions:

HPDG = the amount of harvested gambier leaf

(kg/ha/year);

TKB = the number of cultivation labors

(HKO/ha/year);

LLTM = the area of productive plants (ha);

JB = the types of seeds (dummy),

where: 1: if used the seeds varieties that was

recommended by government; 0: if used the

local seeds varieties;

PPu = the use of fertilizers (dummy),

Analysis of Factors Inﬂuencing the Production of Dried Gambier Sap in Pakpak Bharat District

243

where: 1: if used fertilizers; 0: if did not use

fertilizers;

PPe = the use of pesticides (dummy),

where: 1: if used pesticides; 0: if did not used

pesticides;

JTM = the number of productive plants

(tree/ha);

UTM = the age of productive plants (year);

PB = the experience in farming (year);

PGGK = the production of dried gambier sap

(kg/ha/year);

TKP = the number of processing labors

(HKO/ha/year);

, ..., b

= the regression coefficients or parameters

of the production of dried gambier sap

equation;

, ..., c

= the regression coefficients or parameters

of the amount of harvested gambier leaf

equation;

, c

= the intercept coefficient or constant of

the model;

= the error or residual or disturbance.

Variables influencing the amount of harvested

gambier leaf influence the production of dried

gambier sap indirectly through the amount of

harvested gambier leaf mediation. OLS assumption

test was carried out before the model estimation to

see whether there was a disturbing element in the

regression model (Gujarati, 2004). Normality

assumption test was conducted by the Kolmogorov-

Smirnov test. The multicollinearity assumption test

was conducted by looking at the Tolerance and VIF

values. Moreover, the heteroscedasticity assumption

test was conducted by the Glejser test (Ghozali,

2014).

Furthermore, results of the goodness of fit test,

which included the F-test, and the determination

coefficient value (R

) test were evaluated. The t-test

was carried out to see the independent variables

influencing the amount of harvested gambier leaf

and the production of dried gambier sap. In addition,

the Sobel test was carried out to see the indirect

influence of variables influencing the amount of

harvested gambier leaf on the production of dried

gambier sap through the mediation of the amount of

harvested gambier leaf (Ghozali, 2013).

3 RESULTS AND DISCUSSION

The normality assumption test with Kolmogorov-

Smirnov test on both models showed a significance

value of 0.200 (> 0.05) which means that the residual

data were normally distributed. The multicollinearity

assumption test showed the Tolerance value of all

independent variables > 0.1 and VIF of all

independent variables < 10 which means that there

was no multicollinearity in the models. The

assumption of heteroscedasticity test with Glejser test

showed the significance value of all independent

variables > 0.05, which means that heteroscedasticity

did not occur in the models (Table 4).

Table 1 shows the statistical test result of factors

influencing the amount of harvested gambier leaf.

The model of the factors influencing the amount of

harvested gambier leaf is 0.528 (R-Squared). It

means that 52.8% of the variations of the

independent variables of the number of cultivation

labors and the area of productive plants

explain the

variation of the dependent variable. The types of

seeds, the use of fertilizers, the use of pesticides, the

number of productive plants, the age of productive

plants, and the experience in farming, have been

able to explain the variation of the dependent

variable of the amount of harvested gambier leaf.

The remaining 47.2% is explained by the variations

in other variables that are not included in the model.

The F-statistical probability value of 0.000 (< 0.05)

also has significant influence on the dependent

variable of the amount of harvested gambier leaf.

Table 1: The statistical test result of factors influences the

amount of harvested gambier leaf.

Variables

Statistics Test

C Std. Erro

t Sig.

Constant 1554.665 1303.305 1.193 0.240

The number of

cultivation labors

(HKO/ha/year)

-0.006 0.982 -0.006 0.995

The area of productive

lants (ha)

2143.232 921.615 2.326 0.025

The types of seeds

(

dumm

-1649.479 536.772 -3.073 0.004

The use of fertilizers

(dummy)

1774.538 602.476 2.945 0.005

The use of pesticides

(dummy)

-1061.868 572.449 -1.855 0.071

The number of

productive plants

(plants/ha)

0.571 0.356 1.601 0.117

The age of productive

lants (year)

-132.575 77.979 -1.700 0.097

The experience in

farmin

ear

)

110.278 45.468 2.425 0.020

0.528

F 5.724 0.000

Normality Test (Z) 0.089 0.200

Dependent Variable:

The amount of harvested gambier leaf (kg/ha/year)

ICMR 2018 - International Conference on Multidisciplinary Research

244

Table 2 shows the statistical test result of factors

influencing the production of dried gambier sap. In

the model of the factors influencing the production

of dried gambier sap, the determination coefficient

(R-Squared) is 0.577 which means that 57.7%

variations in the independent variables of the amount

of harvested gambier leaf and the number of

processing labors have been able to explain the

variation of the dependent variable of the production

of dried gambier sap. On the other hand, the

remaining 42.3% is explained by the variations in

other variables that are not included in the model.

The f-statistical probability value of 0.000 (<0.05)

shows that the independent variables of the amount

of harvested gambier leaf and the number of

processing labors included into the model,

simultaneously has a significant influence on the

dependent variable of the production of dried

gambier sap.

Table 2: The statistical test result of factors influences the

production of dried gambier sap.

Variables

Statistics Test

Std.

Erro

t Sig.

Constant 57.111 48.202 1.185 0.242

The number of

processing labors

(

HKO/ha/

ear

)

0.020 0.017 1.141 0.260

The amount of

harvested gambier

leaf

(

/ha/

ear

)

1.625 0.451 3.602 0.001

0.577

F 32.024 0.000

Normalit

Test

(

)

0.085 0.200

Dependent Variable:

The production of dried gambier sap (kg/ha/year)

The function of the factors influencing the

production of dried gambier sap could be written in

the linear equation as follows.

HPDG = 1554.665 - 0.006 TKB + 2143.232

LLTM - 1649.479 JB + 1774.538 PPu -

1061.868 PPe + 0.571 JTM - 132.575 UTM +

110.278 PB

(3)

PGG

= 57.111 + 0.020 HPDG + 1.625 TK

(

)

The number of cultivation labors has a

coefficient value of -0.006, but the significance

value is 0.995 so that it is not significant at α 5% and

α 10%. It means that the number of cultivation

labors has a negative influence but not significant on

the amount of harvested gambier leaf. Therefore, if

there is an increase in the number of cultivation

labors of 1 HKO/ha/year, then the amount of

harvested gambier leaf will decrease by 0.006

kg/ha/year. The cultivation labors were mostly used

in the process of plant maintenance and harvesting.

The majority of gambier farming in Pakpak Bharat

District used family labor. All this time, the gambier

farming itself was still a source of side income. In

general, gambier farmers have other sources of

income. Therefore, the allocation of labors for the

plant maintenance and harvesting had not been

optimal. The plant maintenance was only carried out

if it was time available and as minimum as possible.

The harvesting also still had to experience

constraints on the limited capacity of processing

facilities owned by farmers. Consequently, whatever

number of labors was allocated for harvesting, the

labors would only harvest gambier leaves as much

as the capacity that could be processed by the

processing facilities owned by farmers.

The area of the productive plants has a coefficient

value of 2143.232, and the significance value is 0.025

so that it is significant at α 5%. It means that the area

of the productive plants has a positive and significant

influence on the amount of harvested gambier leaf.

Therefore, if there is an increase in the area of the

productive plants of 1 ha, then the amount of

harvested gambier leaf will increase by 2143.232

kg/ha/year. The larger the area of the productive

plants, the more the number of plants and the amount

of gambier leaf could be harvested.

The types of seeds have a coefficient value of -

1649.479, and the significance value is 0.004 so that

it is significant at α 5%. It means that the types of

seeds have a negative and significant influence on

the amount of harvested gambier leaf. Therefore, if

the farmers use the superior varieties seeds

recommended by the government, then the amount

of harvested gambier leaf will be lower by 1649.479

kg/ha/year than if the farmers use the local varieties

seeds. The superior varieties recommended by the

government succeeded well based on observations in

the area of West Sumatra, which was the largest

gambier production center in Indonesia, on the other

hand, the local variety seeds yielded a higher amount

of gambier leaf in Pakpak Bharat District. The local

varieties were more suitable to be developed in

Pakpak Bharat District due to the location-specific

nature of agricultural commodities. Varieties that are

suitable to be developed in an area will not

necessarily give the same results if developed in

other regions. Local varieties from Pakpak Bharat

District had better adaptability in Pakpak Bharat

District compared to new varieties imported from

other regions.

Analysis of Factors Inﬂuencing the Production of Dried Gambier Sap in Pakpak Bharat District

245

The use of fertilizers has a coefficient value of

1774.538, and the significance value is 0.005 so that

it is significant at α 5%. It means that the use of

fertilizers has a positive and significant influence on

the amount of harvested gambier leaf. Therefore, if

the farmers use the fertilizers, then the amount of

harvested gambier leaf will be higher by 1774.538

kg/ha/year than if the farmers do not use the

fertilizers. There was no location-specific standard

operating procedure (SOP) in carried out the

gambier farming in Pakpak Bharat District. So that

farmers also had not implemented the gambier

farming based on SOP. The use of fertilizers and

pesticides was carried out only modestly. There was

no regular schedule or frequency of using fertilizers

or spraying pesticides. Farmers would use fertilizers

or spray pesticides only if there were excess money

or if it was deemed necessary. The amount and types

were also just as casual and not based on

calculations or specifically recommended dosages.

Gambier plants are usually planted on marginal land,

so fertilization is essential to improve soil fertility.

The use of pesticides has a coefficient value of -

1061.868, and the significance value of 0.071 so that

it is significant at α 10%. It means that the use of

pesticides has a negative and significant influence on

the amount of harvested gambier leaf. Therefore, if

the farmers use the pesticides, then the amount of

harvested gambier leaf will be lower by 1061.868

kg/ha/year than if the farmers do not use pesticides.

Same as in the use of fertilizers, the farmers had not

implemented the gambier farming based on SOP.

When using pesticides, the amount and types were

just as casual and not based on calculations or

specifically recommended dosages. Moreover, the

form of gambier plants themselves is the shrubs

half-propagating, so that an inappropriate pesticides

usage and not according to the recommendations or

excessive can actually damage the plant, especially

the leaves.

The number of productive plants has a

coefficient value of 0.571, but the significance value

is 0.117 so that it is not significant at α 5% and α

10%. It means that the number of productive plants

has a positive but not significant influence on the

amount of harvested gambier leaf. Therefore, if

there is an increase in the number of productive

plants by 1 tree/ha, then the amount of harvested

gambier leaf will increase by 0.571 kg/ha/year. The

more the number of productive plants, the more the

amount of gambier leaf could be harvested.

However, paying attention to the plants spacing is

still very important. Farmers in Pakpak Bharat

District usually plant gambier with varies spacing,

so that the number of productive plants of each

farmer per hectare varies greatly. In fact, spacing

that is too narrow, can interfere the plant growth,

while too tenuous spacing will be less efficient

because the number of plants produce will decrease.

The age of productive plants has a coefficient

value of -132.575, and the significance value of

0.097 so that it is significant at α 10%. It means that

the age of productive plants has a negative and

significant influence on the amount of harvested

gambier leaf. Therefore, if there is an increase in the

age of productive plants by 1 year, then the amount

of harvested gambier leaf will decrease by 132.575

kg/ha/year. The gambier plants were not at a

productive age so that an increase of age would

actually reduce the amount of harvested gambier

leaf.

The experience in farming has a coefficient value

of 110.278, and the significance value of 0.020 so

that it is significant at α 5%. It means that the

experience in farming has a positive and significant

influence on the amount of harvested gambier leaf.

Therefore, if there is an increase in the experience in

farming by 1 year, then the amount of harvested

gambier leaf will increase by 110.278 kg/ha/year.

The higher the experience of farmers in farming

gambier, the higher their knowledge and ability,

therefore they will be better and more efficient in

farming gambier.

The amount of harvested gambier leaf has a

coefficient value of 0.020, and the significance value

of 0.260 so that it is not significant at α 5% and α

10%. It means that the amount of harvested gambier

leaf has a positive but not significant influence on

the production of dried gambier sap. Therefore, if

there is an increase in the amount of harvested

gambier leaf by 1 kg/ha/year, then the production of

dried gambier sap will increase by 0.020 kg/ha/year.

The amount of harvested gambier leaf has no

significant influence on the production of dried

gambier sap because the capacity of the processing

facilities was not optimal. As much as any gambier

leaves could harvest by farmers, farmers could only

process as much dried gambier sap as can be

processed by the available processing facilities,

while the rest would be the leftover. There used to

be a factory that could process gambier leaves into

dried gambier sap in Pakpak Bharat District, so that

the farmers could sell their gambier leaves to be

processed at the factory. However, the factory was

no longer operating, so farmers were forced to

process their gambier leaves into dried gambier sap

with traditional and limited processing tools. It

caused gambier leaves to be processed per day only

ICMR 2018 - International Conference on Multidisciplinary Research

246

as much as the capacity of the boiler for boiling and

the available labors. The quality, size, and shape of

the dried gambier sap produced were also not well

standardized, so it would be difficult to export.

The number of processing labors has a

coefficient of 1.625, and the significance value of

0.001 so that it is significant at α 5%. It means that

the number of processing labors has a positive and

significant influence on the production of dried

gambier sap. Therefore, if there is an increase in the

number of processing labors of 1 HKO/ha/year, then

the production of dried gambier sap will increase by

1.625 kg/ha/year. The more the number of

processing labors, the more the capacity of gambier

leaf that can be processed by farmers to become

dried gambier sap, so that will increase the

production of dried gambier sap.

Table 3: The statistical test result of factors influences the

production of dried gambier sap indirectly through the

mediation of the amount of harvested gambier leaf.

Variables

Statistics Test

B x C Std. Erro

t t

table

The number of

cultivation labors

(

HKO/ha/

ear

)

-0.00012 0.02578 -0.00466 2.020

The area of

productive plants

(ha)

42.86464 43.73470 0.98011 2.020

The types of

seeds

(

dumm

-32.98958 31.38189 -1.05123 2.020

The use of

fertilizers

(

dumm

35.49076 34.06095 1.04198 2.020

The use of

pesticides

(dummy)

-21.23736 23.48722 -0.90421 2.020

The number of

productive plants

(tree/ha)

0.01142 0.01347 0.84756 2.020

The age of

productive plants

ear

)

-2.65150 3.04452 -0.87091 2.020

The experience

in farming (year)

2.20556 2.22238 0.99243 2.020

Dependent Variable:

The production of dried gambier sap indirectly through the

mediation of the amount of harvested gambier leaf

(kg/ha/year)

Table 3 shows the statistical test result of factors

influencing the production of dried gambier sap

through the mediation of the amount of harvested

gambier leaf. The Sobel test showed the significance

value (p-Value) of all independent variables > 0.05

which means that it was not significant at α 5% or α

10% (Table 5). It means that the variables that

influence the amount of harvested gambier leaf

could not influence the production of dried gambier

sap indirectly through the mediation of the amount

of harvested gambier leaf. Variables that influenced

the amount of harvested gambier leaf would be able

to influence the production of dried gambier sap

indirectly if the amount of harvested gambier leaf

itself could influence the production of dried

gambier sap.

The magnitude of the indirect influence from

variables influencing the amount of harvested

gambier leaf to the production of dried gambier sap

through the mediation of the amount of harvested

gambier leaf could be interpreted as follows.

1. The number of cultivation labors has an indirect

coefficient value of -0.00012 which means that if

there is an increase in the number of cultivation

labors of 1 HKO/ha/year, then the production of

dried gambier sap will decrease by 0.00012

kg/ha/year.

2. The area of the productive plants has an indirect

coefficient value of 42.86464, which means that

if there is an increase in the area of the

productive plants of 1 ha, then the production of

dried gambier sap will increase by 42.86464

kg/ha/year.

3. The types of seeds have an indirect coefficient

value of -32.98958 which means that if the

farmers use the superior varieties seeds

recommended by the government, then the

production of dried gambier sap will be lower by

32.98958 kg/ha/year than if the farmers use the

local varieties seeds.

4. The use of fertilizers has an indirect coefficient

value of 35.49076, which means that if the

farmers use the fertilizers, then the production of

dried gambier sap will be higher by 35.49076

kg/ha/year than if the farmers do not use the

fertilizers.

5. The use of pesticides has an indirect coefficient

value of -21.23736, which means that if the

farmers use the pesticides, then the production of

dried gambier sap will be lower by 21.23736

kg/ha/year than if the farmers do not use

pesticides.

6. The number of productive plants has an indirect

coefficient value of 0.01142, which means that if

there is an increase in the number of productive

plants by 1 tree/ha, then the production of dried

gambier sap will increase by 0.01142 kg/ha/year.

7. The age of productive plants has an indirect

coefficient value of -2.65150, which means that

if there is an increase in the age of productive

Analysis of Factors Inﬂuencing the Production of Dried Gambier Sap in Pakpak Bharat District

247

plants by 1 year, then the production of dried

gambier sap will decrease by 2.65150 kg/ha/year.

8. The experience in farming has an indirect

coefficient value of 2.20556, which means that if

there is an increase in the amount of harvested

gambier leaf by 1 kg/ha/year, then the production

of dried gambier sap will increase by 2.20556

kg/ha/year.

4 CONCLUSIONS

In the area of the productive plants, the use of

fertilizers, and the experience in farming, has a

positive and significant influence on the amount of

harvested gambier leaf. The types of seeds, the use

of pesticides, and the age of productive plants, have

a negative and significant influence. The number of

productive plants has a positive influence, and the

number of cultivation labors, have a negative

influence but not significant. The number of

processing labors has a positive and significant

influence on the production of dried gambier sap;

while the amount of harvested gambier leaf has a

positive but not significant influence. Variables

influencing the amount of harvested gambier leaf

cannot influence the production of dried gambier sap

indirectly through the mediation of the amount of

harvested gambier leaf due to the inadequate

processing tools capacity and technology. Variables

influencing the amount of harvested gambier leaf

would be able to influence the production of dried

gambier sap indirectly if the amount of harvested

gambier leaf themselves could influence the

production of dried gambier sap. Government and

academics are advised to conduct research and

guidance to farmers regarding the gambier varieties

and the standard operating procedures (SOP) in

carrying out the location-specific gambier farming

in Pakpak Bharat District. The government and

investors are also suggested to be able to facilitate

farmers related to the efforts to increase the capacity

and technology of gambier processing facilities.

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West Sumatra Province] (Thesis), Sekolah Pasca

Sarjana [Post Graduate School] Institut Pertanian

Bogor. Bogor.

Badan Pusat Statistik Indonesia [BPS-Statistics

Indonesia], 2014. Luas Tanaman dan Produksi

Gambir Tanaman Perkebunan Rakyat menurut

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ICMR 2018 - International Conference on Multidisciplinary Research

248

APPENDIX

Table 4: The multicollinearity and heteroskedasticity test

result of factors influence the amount of harvested

gambier leaf model and the production of dried gambier

sap model.

Variables

Multicollinearity

Test

Heteroskedasticity

Test

Tolerance VIF t Si

endent Var.: The amount of harvested

ambier leaf

The number of

cultivation labors

(HKO/ha/year)

0.728 1.374 0.999 0.324

The area of

productive plants

(ha)

0.665 1.503 0.636 0.528

The types of

seeds (dummy)

0.961 1.041 -1.322 0.193

The use of

fertilizers

(dummy)

0.746 1.341 -0.271 0.787

The use of

pesticides

(dummy)

0.790 1.266 1.420 0.163

The number of

productive plants

lants/ha

)

0.679 1.474 1.141 0.261

The age of

productive plants

ear

)

0.586 1.708 -0.033 0.974

The experience in

farmin

ear

)

0.837 1.195 -1.594 0.119

endent Var.: The

roduction of dried

ambier sa

The number of

processing labors

(

HKO/ha/

ear

)

0.328 3.048 -0.798 0.429

The amount of

harvested gambier

leaf (kg/ha/year)

0.328 3.048 0.857 0.396

Table 5: The Sobel test result of factors influences the

production of dried gambier sap indirectly through the

mediation of the amount of harvested gambier leaf.

Variables

Sobel

Test

Sobel’s Z Two-tailed p Value

Dependent Variable:

The production of dried gambier sap indirectly through the

mediation of the amount of harvested gambier leaf

The number of

cultivation labors

(

HKO/ha/

ear

)

-0.00611 0.99513

The area of

productive plants

(

)

1.04978 0.29382

The types of seeds

(

dumm

-1.09870 0.27190

The use of fertilizers

(dummy)

1.09254 0.27460

The use of pesticides

(

dumm

-0.99350 0.32047

The number of

productive plants

(plants/ha)

0.94864 0.34280

The age of

productive plants

(year)

-0.96743 0.33333

The experience in

farming (year)

1.05852 0.28982

Analysis of Factors Inﬂuencing the Production of Dried Gambier Sap in Pakpak Bharat District

249