Growth and Production Response of Several Local Sweet Potatoes

(Ipomoea batatas L.) Clones on Multiple Trimming Levels

Ardhea Ade Putra Pratama, Nini Rahmawati and Asil Barus

Faculty of Agriculture, Universitas Sumatera Utara, Medan 20155, Sumatera Utara, Indonesia.

Keywords: Local clones, trimming, sweet potato production

Abstract: Trimming is an effort to reduce plant parts to optimize plant parts that are important for growth and

production, to increase crop productivity. This research aim was to determine the growth and production

response of several local sweet potato clones on several trimming levels. This research used a randomized

block design with two factors, local sweet potato clones (local clone of Dusun Bintang Meriah, Sirube-rube,

Dolok Sinumbah) and several trimming levels (without trimming, trimmed after tendrils reach 50 cm long,

75 cm long, and 100 cm long).This research was carried out in Balai Penelitian Tanaman Sayur, Tongkoh

Village, Berastagi, Karo Regency from July 2018 to January 2019. The results showed that the local sweet

potato clones had a good growth and production response to several levels of trimming. Three local clones

did not affect significantly in the length of tendrils, tuber weight per sample, number of tubers per sample,

crown wet weight, and harvest index. Trimming levels did not significantly affect the length of tendrils,

tuber weight per sample, number of tubers per sample, and canopy wet weight, but significantly affect the

harvest index. The best level of trimming was trimmed after the length of the tendrils is 75 cm.

1 INTRODUCTION

Sweet potato (Ipomoea batatas L.) originating from

West Indies or South America, is an additional food

ingredient or substitute for rice that has received

public attention. Aside from being a food ingredient,

sweet potatoes are also used as industrial raw

materials for example flour, liquid sugar, fodder, and

alcohol (Sisharmini et al., 2005).

Data from the Ministry of Agriculture in

2016, production during the 1995-2016 period

fluctuated but tended to increase. Sweet potato

production in the 1995-2016 period increased,

averaging at 0.11% per year, while in the period of

2012 to 2016, Sweet potato production decreased by

an average of 4.14% per year. The increase in

production growth on Java Island in the period of

1995-2016 rose by 1.03%, while outside of Java

decreased by 0.06% per year.

There are several obstacles in increasing the

productivity and income of sweet potato farmers in

several countries. One of them is the lack of superior

varieties suitable for cultivation with the local

environment (Low, et al. 2009). Efforts that can be

made to overcome this problem are by using

superior seeds or high-yielding local seedlings,

improving the management of sweet potato farming

and by controlling the number of canopy above the

ground (Sasongko, 2009). The use of local superior

clones is a reliable technology not only in terms of

increasing agricultural production but also can

increase the income and welfare of farmers. Superior

clones generally have prominent properties in terms

of high yield and resistance to certain plant pest

organisms. Using superior clones that are resistant to

pests and diseases is the cheapest way to suppress

plant disturbances without any worries on negative

environmental impacts (Jayanto, 2009).

Improvement of cultivation methods is

another effort that can be done to increase sweet

potato production, one of which is by trimming the

leaves. Extraction or trimming of sweet potato

leaves during its vegetative stage has been common

in many countries. Trimmed leaves are used for

vegetables or animal feed. The plant's response to

defoliation depends on more than the total amount of

leaf lost. It is also known that the intensity of

defoliation can vary along the gradient of nutrient

availability and that defoliation can change the

relationship of competition between species (Ahmed

et al, 2012; Ahmadi et al, 2009).

176

Pratama, A., Rahmawati, N. and Barus, A.

Growth and Production Response of Several Local Sweet Potatoes (Ipomoea batatas L.) Clones on Multiple Trimming Levels.

DOI: 10.5220/0008551301760180

In Proceedings of the International Conference on Natural Resources and Technology (ICONART 2019), pages 176-180

ISBN: 978-989-758-404-6

According to Panggabean et al., (2014), trimming is

an activity to improve and optimize parts of plant

organs by removing or reducing other parts of plant

organs. Trimming is expected to increase

photosynthesis results hence maximize growth and

production. Suminarti (2016) research showed that

in untrimmed sweet potato plants, there is less

agronomic balance between parts of the organ above

the ground and parts of the organ below the surface

of the soil. Sweet potato plants which were trimmed

once, produce tubers with a diameter, length and

greater weight than ones without trimming. In

addition, Irawati and Setiari (2006) stated that

trimming can also improve lighting from sunlight to

all parts of the plant hence the photosynthesis

process can take place perfectly and can reduce

moisture hence plants can avoid attacks from pests

and diseases.

This research aim was to determine the growth

and production response of several local sweet

potato (Ipomea batatas L.) clones on several

trimming levels.

2 MATERIALS AND METHODS

2.1 Research Area

The research was carried out on the field of Balai

Penelitian Tanaman Sayur, Tongkoh Village,

Berastagi, Karo Regency with an altitude of 1450

meters above sea level, starting from May 2018 to

January 2019.

2.2 Procedures

This research used a randomized block design with

two factors, the first factor was the type of local

sweet potato clones (local clones of Dusun Bintang

Meriah, local clones of Sirube-rube, local clones of

Dolok Sinumbah) and the second factor was the

level of trimming (without trimming, trimmed after

tendrils length is 50 cm, trimmed after tendrils

length is 75 cm, trimmed after tendrils length is 100

cm).

This research started from land preparation,

making beds, preparing the seedlings, mulching,

planting, plant maintenance, fertilizing, and

analyzing morphological parameters including

tendrils length, canopy wet weight, number of

tubers, tuber weight per sample and harvest index.

2.3 Data analysis

Retrieval of morphological character data, namely

the length of tendrils carried out when the plant was

at 12 weeks after planting (WAP). Observation of

plant wet weight, number of tubers, tuber weight per

sample and harvest index were observed when the

plants were at 20 WAP.

Data were analyzed statistically by the F test and

continued by the Duncan Multiple Range Test

(DMRT) test at α 5%.

3 RESULTS AND DISCUSSIONS

3.1 Vegetative Growth of Sweet

Potatoes

The local clones had no significant effect on the

parameters of tendrils length but had significant

effect of canopy wet weight (Table 1). Clones from

Dusun Bintang Meriah had the highest tendrils

length compared to other local clones. Dolok

Sinumbah clone produced the highest canopy wet

weight compared to other treatments. This was due

to the three clones come from the area relatively had

similar altitude with the growing environment of

cultivated sweet potatoes. Kays et al. (2005)

reported that vegetative growth and the yield of local

sweet potato tubers were strongly influenced by the

growing environment. Okogbenin et. al., (2013) also

stated that plant growth would be better in areas that

have relatively high light intensity.

Table 1: The length of tendrils and canopy wet weights of

several local sweet potatoes clones

Local Clones

Length of

Tendrils (cm)

Canopy Wet

Weights (g)

Dusun Bintang

Meriah

76.65

901.79 b

Sirube-rube

65.88

864.67 c

DolokSinumbah

67.29

906.65 a

Description: The numbers followed by the same letters

showed no significant difference in the

Duncan Multiple Range Test at the level of α

= 5%.

The trimming levels showed no significant effect on

the length of tendrils and canopy wet weight (Table

2). Treatment without trimming resulted with the

highest length of tendrils and canopy wet weight

when compared with other treatments. Novianti

(2016) research also showed the same results,

namely trimming treatment resulted in an average

Growth and Production Response of Several Local Sweet Potatoes (Ipomoea batatas L.) Clones on Multiple Trimming Levels

177

growth of shorter stem length than treatment without

trimming, whereas trimming treatment resulted in

higher growth rate of primary branch length than

treatment without trimming. Jayanti et. al., (2016)

also stated that trimming sweet potato plants can

break apical dominance, thus inhibiting the

development of plant stems.

Table 2: Length of tendrils and canopy wet weights on

various levels of trimming.

Without Trimming

Length of

Tendrils

(cm)

Plant Wet

Weight

(g)

Without Trimming

75.78

1.150.89

Trimmed when reach 50 cm

67.39

678.36

Trimmed when reach 75 cm

66.42

800.83

Trimmed when reach 100 cm

70.17

934.06

In line with the length of the tendrils, untrimmed

sweet potato plants showed the highest plant wet

weight increased up to 66.66%, compared to the wet

weight of the trimmed plants.Plants which were

trimmed after the tendrils length reach 50 cm had

the lowest plant wet weight. The results showed that

the wet weight on sweet potato plants would be

lower if the plants were trimmed on the shorter

tendrils length. Yooyongwech et. al., (2014) also

related the decrease in leaf production with the age

of sweet potato plants and emphasized that the leaf

area is very important in determining the growth and

level of accumulation of dry matter at the storage

root.

3.2 Sweet Potato Production

The data in table 3 showed that the number of tubers

and tuber weights in the local sweet potato clones

did not show any significant differences. The local

Dolok Sinumbah clone produced the highest number

of tubers per sample compared to other local clones

which differed from 7.73% compared to the number

of tubers in clones from Dusun Bintang Meriah. On

the contrary, the highest tuber weight per sample

was produced by the local Dusun Bintang Meriah

clone compared to other local clones. Villordon et

al., (2009) stated that sweet potato yields varied

greatly. Differences in yields are related to various

factors such as cultivars, propagation matters,

environment and soil. Propagation matters and the

same cultivation environment in this research were

thought to cause the number of tubers and tuber

weight per sample not significantly different

between those local clones.

Table 3: The effect of several local sweet potato clones on

the number of tubers and tuber weight per sample.

Local Clones

Number of

tubers/sample

(tuber)

Tuber weight /

sample (g)

Dusun Bintang

Meriah

4.27

988.10

Sirube-rube

4.42

777.48

DolokSinumbah

4.60

895.42

The data in Table 4 showed that trimming treatment

had no significant effect on the number of tubers and

tuber weight per sample. The treatment of trimmed

after 75 cm resulted in the highest number of tubers

which increased by 11.14% compared to plants that

were not trimmed.Astrini (2012) stated that the

treatment of trimming on sweet potato plants can

increase tuber yield. This was due to the reduced of

shoot dominance and the increased of lateral

growth.Fitohormones, auxins and cytokines that are

produced at the shoots can stimulate the growth of

side shoots, resulting in a growth balance of the

canopy and tubers which will increase the assimilate

allocation to the tubers.

Table 4: Number of tubers and tuber weights per sample

against various levels of trimming

Trimming Levels

Number of

tubers/sample

(tuber)

Tuber

weights

/sample (g)

Without Trimming

4.22

821.94

Trimmed when reach 50 cm

4.47

942.31

Trimmed when reach 75 cm

4.69

1.007.44

Trimmed when reach 100 cm

4.33

776.31

The tuber weight illustrates the ability of a plant in

translocating the assimilate to the part of the storage

organ from the total assimilation obtained. Table 4

showed the highest tuber weight was also produced

on plants that were trimmed after the length of

tendrils was 75 cm which increased by 42.65%

compared to the lowest tubers weight on the plants

that trimmed after the length of tendrils was 100 cm.

The same results were also conveyed by Rahmiana

et. al., (2015) that the tuber weight of trimmed sweet

potatoes plants increased compared with without

trimming. The thing that needs to be considered in

sweet potato cultivation is the level and phase of

trimming, if the trimming is too excessive or the

phase is less precise it can reduce tuber production.

Lebot (2009) and An et. al., (2003) stated that

excessive trimming in sweet potatoes will negatively

affect the production and cause a decrease in crop

yields.

ICONART 2019 - International Conference on Natural Resources and Technology

178

Table 5: The effect of local sweet potato clones on harvest

index

Lokal Clones

Harvest Index

Dusun Bintang Meriah

0.50

Sirube-rube

0.44

DolokSinumbah

0.47

According to Wahyuni et. al., (2004) the harvest

index can be used as a parameter to see the

proportion of photosynthate allocation efficiency

and photosynthate translocation for more tubers

hence the proportion of tuber weight must be more

than 50% of the total weight of the plant.Based on

the harvest index observations in some local sweet

potatoes clones were not significantly different

(Table 5). Local clones from Dusun Bintang Meriah

produced the highest harvest index compared to

local clones of Sirube-rube and local clones of

Dolok Sinumbah.The harvest index value (HI) is

obtained from the ratio of yield (tuber) compared to

the total biomass, according to Wahyuni et. al.,

(2004), clones with high tuber yields generally

followed by a high harvest index.This statement was

in accordance with the research results that the

tubers production of clone from Dusun Bintang

Meriah was the highest compared to other local

clones which showed that the clone was more often

divided photosynthates to the tubers yield. Sitompul

(2016) also explained that plants which have a high

harvest index, the economic yield will be high too,

this is presumably because the harvest index is

carbon mobilization.

Table 6: The effect of the trimming level on the Harvest

Index

Trimming Level

Harvest Index

Without Trimming

0,33 b

Trimmed when reach 50 cm

0,53 a

Trimmed when reach 75 cm

0,53 a

Trimmed when reach 100

0,43 b

Description: The numbers followed by the same letters

showed no significant difference in the

Duncan Multiple Range Test at the level of

α = 5%.

The data in table 6 showed that the treatment of

trimming levels had a significant effect on the

harvest index. The treatment of trimmed after 50 cm

and 75 cm had the highest harvest index compared

to other trimming level treatments. These results

indicated that proper trimming on sweet potatoes

affected the amount of photosynthate produced and

supports more photosynthate translocation into the

tubers. This was due to the trimmed plants had fewer

number of leaves and minimizes the effect of shade

between the leaves, hence leaves can function as a

source. Astuti et. al., (2012) explained that the

number of leaves influences the plant growth

because it is related to the ability to carry out

photosynthetic activities. Efficient leaves for

photosynthesis are leaves that can absorb sunlight

optimally. Treatment of leaf trimming at a certain

level will increase yield, but excessive leaf trimming

will not increase crop yields and even can reduce the

yield. This was because the photosynthetic rate from

remaining leaves was not capable to compensate for

the increasing photosynthate requirements.

Suminarti et al (2016) also stated that the number of

canopy above the ground can affect photosynthetic

ability, hence the ability to translocate assimilates is

also affected, namely assimilate translocation to the

part of the storage organ from the total assimilation

obtained.

4 CONCLUSIONS

The local sweet potato clones had a good growth and

production response to several levels of trimming.

The three local clones were not significantly

different in the parameters of tendrils length, tuber

weight per sample, number of tubers per sample, and

harvest index. But significantly different in the

parameter canopy wet weight. The treatment of

trimming levels did not significantly affect the

length of tendrils, tuber weight per sample, number

of tubers per sample and canopy wet weight, but

significantly affected the harvest index parameters.

The best trimming levels was trimmed after 75 cm

long.

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