Morphophysiological Characteristics Analysis of Tuber from
Multiple Sweet Potato Clones (Ipomea batatas Lamb.) with Mulching
Application
Rosnidar, Dharma Bakti and Nini Rahmawati
Faculty of Agriculture, Universitas Sumatera Utara, Medan 20155, Sumatera Utara, Indonesia.
Keywords: Clones, Morphophysiological Characteristics, Mulching.
Abstract: The purpose of this research was to determine the morphophysiological characteristics of sweet potato tubers.
The design used in this research was a Randomized Group Design consisting of the first factor, namely sweet
potato clones with different color of tuber flesh (yellow, purple, orange) and the second factor was types of
mulching (without mulch, plastic mulch and straw mulch). The results showed that the highest water content
was in orange-fleshed sweet potato clones. Tuber flesh hardness in the three types of sweet potato was not
significantly different, but the results of the observation showed that the higher the tuber water content the
softer the tuber flesh. The highest betacarotene content was found in sweet potato clones with orange-fleshed
tuber (845 mg/100 g) and the lowest was in sweet potato clones with purple-fleshed tuber (566 mg/100 g).
The highest anthocyanin content was found in sweet potato clones with purple-fleshed tuber (10.46 mg/100
g) and the lowest was in sweet potato clones with yellow-fleshed tuber (3.73 mg/100 g). Mulching application
in this study significantly affected the water content and hardness of sweet potato tuber but did not
significantly affect the levels of betacarotene and anthocyanin.
1 INTRODUCTION
Sweet potato (Ipomoea batatas Lamb.) is an
alternative food crop that can be used to diversify
food to reduce dependence on rice and wheat. Sweet
potatoes can be planted throughout the year and can
grow on various types of soil and drought resistance
(Masango, 2014).
Generally, sweet potatoes are cultivated on dry
land, gardens and yards, as well as in rainfed lowland
fields. Sweet potato is used as a high-fiber, feed, and
industrial food ingredient. The storage capacity of the
tuber is quite good. Sweet potatoes have value in
modern society because they function as natural and
healthy foods, this is related to the presence of
anthocyanin and beta-carotene compounds they
contain (Masango, 2014; Husna et al. 2013;
Prabhavat at al. 2008).
Anthocyanins contained in sweet potatoes can
block the rate of free radical cell damage due to
nicotine, air pollution and other chemicals.
Anthocyanin plays a role in preventing aging,
deterioration in memory and senility, polyps, gout,
people with stomach ulcers (stomach acid), coronary
heart disease, cancer and degenerative diseases, such
as arteosklerosis. In addition, anthocyanin also has
the ability to be antimutagenic and anti-carcinogenic
to mutagens and carcinogens found in food and
processed ingredients, prevent disruption in liver
function, antihypertensive and reduce blood sugar
levels (antihypergicemic) (Rumbaoa et al. 2009;
Elisabeth et al. 2007; Ameny et al. 1997).
Beta-carotene has a very yellow color and is the
most active form of provitamin A, which is found in
two interconnected retinol molecules. Carotenoids
are present in plant chloroplasts and act as catalysts in
photosynthesis carried out by chlorophyll. Beta-
carotene (β-carotene) is an organic compound and is
classified as a terpenoid. β-carotene is a red-orange
pigment that is very abundant in plants and fruits.
Beta-carotene is thought to have many functions that
other compounds do not have. The amount needed by
the body is only the size of milligrams per day. But if
it is not fulfilled it can cause a disruption of function
(Kusumaningtyas et al., 2009). The benefits of beta
carotene for the body are to prevent and reduce the
risk of cancer. Eating foods or fruits that contain beta-
carotene is expected to support nutritional needs and
Rosnidar, ., Bakti, D. and Rahmawati, N.
Morphophysiological Characteristics Analysis of Tuber from Multiple Sweet Potato Clones (Ipomea batatas Lamb.) with Mulching Application.
DOI: 10.5220/0008551401810186
In Proceedings of the International Conference on Natural Resources and Technology (ICONART 2019), pages 181-186
ISBN: 978-989-758-404-6
Copyright
c
2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
181
increase immunity. The antioxidant properties found
in beta carotene can protect plants and
microorganisms from damaging sunlight (Listya,
2010).
In Binjai city, there are three clones commonly
planted by farmers, namely yellow, purple and orange
flesh clones. But until now research on the content of
secondary metabolites from each clone has never
been done. Sweet potato production in Binjai city in
2016 was only 771.62 tons with a harvest area of 51
ha. The low production in Binjai city apart from the
limited of sweet potato cultivation fields was also
caused by several obstacles including, the disturbance
of pests and diseases and technical cultural actions
that were still not good. Therefore, in this research
mulch was used as a method of natural technical
culture to control pest disorders that commonly attack
sweet potato plants. In addition, the use of mulch is
expected to improve the quality of sweet potato tuber
characteristics.
2 MATERIALS AND METHODS
2.1 Research Area
This research was conducted in Cengkeh Turi
Village, Binjai Utara District, Binjai City. and
starting from July to November 2018, with an altitude
of ± 28 m above sea level. Analysis of anthocyanin
and beta-carotene levels was carried out at Tissue
Culture Laboratory Faculty of Agriculture
Universitas Sumatera Utara. Analysis of water
content and tuber texture at Food Technology
Laboratory Faculty of Agriculture Universitas
Sumatera Utara. The materials used were 3 clones of
sweet potato plants from Binjai (yellow flesh-tuber,
purple flesh-tuber, orange flesh-tuber), urea fertilizer,
SP 36 and KCl. The tools used include hoes, plastic
mulch, straw, plastic rope, labels, scales, knives,
shoves, penetrometers, stationeries and other
supporting tools.
2.2 Research Methodology
The design used in this research was Randomized
Block Design with 3 replications, consisted of the
first factor, namely Sweet Potato clones, with 3 levels
of treatment, yellow flesh-tuber clones (B1), purple
flesh-tuber clones (B2) and orange flesh-tuber clones
(B3). The second factor was the type of mulch;
without mulch (A0), plastic mulch (A1) and straw
mulch (A2).
The data were analysed by Analysis of Variance
(ANOVA) and the follow-up test on the treatment
that was significantly affected was by Duncan's
Multiple Range Test (DMRT) at the level of 5%.
2.3 Research Implementation
The research implementation began with the
cultivation of land by cleaning the grasses and then
treating the soil until it is loose and then left it for 1
week. The loose soil was made into mounds with the
bottom width size of 60 cm, the height was 40 cm and
the distance between mounds was 40 cm and the
length of the mound was 2 m as many as 27
experimental plots.
Mounds that had been prepared for planting was
made into 10 cm array deep and with 30 cm spacing
between plants, seedlings planted ½ part of shoot
cuttings that have been provided then the soil was
compacted near the base of the cuttings. Fertilization
was done once during planting with a dose: 100 kg
Urea/ha, SP36 50 kg/ha, KCl 50 kg/ha. Fertilization
was carried out in an array at a distance of 7 cm with
plants and a depth of 5 cm. Installation of Black Silver
Plastic mulch (PHP) was carried out together with the
installation of straw mulch which was about a week
before planting. The use of straw with a dose of 5
tons/ha by placing it covered the entire surface of the
beds.
Watering was done once every 2 days until 2
months, while the age of the plant after 2 months was
watered once a week. Watering was done in the
morning. If rainy day was not watered. Weeding was
done to clean up weeds in the crop. Weeding was
done at the age of 1 month after planting or when it
looked a lot overgrown with weeds. Removal of the
stem was aimed to avoid the formation of small
tubers on the stem segment that propagates. The stem
lifting treatment was carried out on plants aged 60
days after planting. Observations were made on plant
samples taken from each treatment plot which was
carried out after the plants were harvested at the age
of 4 months.
3 RESULTS AND DISCUSSIONS
3.1 Tuber Water Content
The tuber water content in the three sweet potato
clones can be seen in Table 1. The highest sweet
potato water content was found in orange flesh sweet
potato clones which were equal to 74.02% followed
by purple flesh sweet potato clones of 69.02% and
ICONART 2019 - International Conference on Natural Resources and Technology
182
yellow flesh sweet potato clones of 63.17%.
According to Antarlina (1997), sweet potatoes have
high water content if the value is more than 73.5%
and classified as low if the value is less than 65.5%.
Based on these criteria, the orange flesh clones
included as high water content and yellow flesh sweet
potato clones included as low water content. Ginting
et al (2015) stated that sweet potatoes which have low
water content will have a high level of dry matter.
Sweet potatoes that have high levels of dry matter
are suitable for flour raw materials because they will
produce high yields (Antarlina, 1997). According to
the National Standardization Agency (SNI 01-4493:
1998), the requirements for quality I sweet potato
water content (tuber weight> 200 gr) are 60%, thus
from the three clones above, it is sufficient to fulfill
the requirements to be used as a source of food.
Tubers with high water content such as orange flesh
clones are good as a source of food consumed directly
because they can facilitate digestion. As a food
ingredient, tubers with low water content can be
increased in water content when processing, namely
by boiling or steaming. The difference in water
content is mainly due to differences in
clones/varieties, because the three clones are planted
at the same location and season (Ginting et al, 2015).
Table 1: Water content in three sweet potato clones with the
use of mulch.
Clone
Water Content (%)
Yellow flesh-tuber (B1)
63,17 b
Purple flesh-tuber (B2)
69,02 b
Orange flesh-tuber (B3)
74,02 a
Mulch
Without Mulch ( A0)
70,02
Plastic Mulch (A1)
69,81
Straw Mulch (A2)
70,34
Description: Numbers followed by the same notation on
the same line showed no significant
difference according to Duncan's Multiple
Range Test at the level of 5%.
The data in Table 1 showed the use of mulch both
plastic mulch and straw mulch, not having a
significant effect on sweet potato water content.
However, from the water content data obtained, the
use of straw mulch, yielded quite high levels of sweet
potato water content, equal to 70.34% followed by
without mulch at 70.02% and the use of plastic mulch
at 69.81%. The high levels of sweet potato water
content on the use of straw mulch are thought to be
related to the availability of soil moisture content.
Application of organic mulch like straw in this crop
was proven to be able to maintain soil moisture.
According to Gillespie et al (1992), organic mulch is
plant residues that are spread on the surface of the
soil. Mulch is useful for protecting the soil surface
from exposure to rain, erosion, maintaining moisture,
structure, and soil fertility. Research conducted by
Afandi (2013) which used organic mulch in the form
of cassava peel, explained that soil water content by
cassava mulch application can relatively control the
loss of water from the soil compared to soil without
mulch. The use of mulch is a matter that needs
attention, because it can control the loss of water from
the soil. In the treatment of plastic mulch, tuber
moisture content was lower than in the use of straw
and without mulch, because the soil water content in
the treatment of plastic mulch was also low. This was
because, at the time of planting, it was carried out on
rainfed land hence the source of water was from
rainwater. In the treatment with plastic mulch, found
dry beds with inadequate rainwater supply, because
most of the beds surface were covered with plastic
mulch.
3.2 Tuber-fleshed Hardness
Tuber-flesh hardness was measured by a
penetrometer. Measurements were made at the base,
middle and end of the sweet potato, each with 1 time
stabbing. The penetrometer rod was held and the
penetrometer needle was inserted vertically and
carefully over the sweet potato surface by pressing the
needle into the sweet potato for a few seconds. The
scale value can be read on the measurement results
indicated by the penetrometer scale, added together
then averaged. The larger the scale value shown, the
softer the texture. According to Suwanto et al. (2012),
the softer the sample, the penetrometer suppressor
will sink deeper and show an increasingly large
number.
Hardness or tuber texture is influenced by tuber
moisture content. The higher the water content, the
texture of the material will be softer (Purnomo, 1995).
In Table 2 it can be seen that the hardness of tuber-
flesh from the three clones was not significantly
different. The orange flesh clones with the highest
water content showed a high hardness scale (3.96
gr/mm2), which showed that this sweet potato clone
was softer compared to yellow and purple flesh sweet
potato clones. On the other hand, yellow flesh sweet
potato clones with the lowest water content showed
the lowest hardness scale (3.84 gr/mm2) which means
that this sweet potato clone was the hardest compared
to the other two clones. This indicated that the tuber
moisture content was related to the hardness of tuber-
flesh. Ginting et al (2008) research also showed the
Morphophysiological Characteristics Analysis of Tuber from Multiple Sweet Potato Clones (Ipomea batatas Lamb.) with Mulching
Application
183
same results, namely sweet potato clones which have
a small hardness value (hard texture) is having a small
water content. This was presumably due to
differences in other chemical compositions which can
affect the hardness of tubers such as starch, especially
the components of amylose, amylopectin and fiber.
Table 2: Tuber-flesh hardness in three sweet potato clones
using mulch.
Clone
Tuber-flesh Hardness
(kg/mm
2
)
Yellow flesh-tuber (B1)
3,84
Purple flesh-tuber (B2)
3,87
Orange flesh-tuber (B3)
3,96
Mulch
Without Mulch ( A0)
4,31
Plastic Mulch (A1)
3,79
Straw Mulch (A2)
3,57
The use of mulch had no significant effect on
texture or tuber hardness, but it can be seen from table
2 that the use of straw mulch showed the smallest
hardness number (3.57 gr/mm2) which means it was
the hardest tuber compared to the treatment of
without mulch which showed the highest hardness of
4, 31 gr/mm2 which means it was the softest tuber.
This was thought due to straw application increased
the chemical content in the tubers, for example; starch
which can cause the tuber to become harder. Because
the application of organic matters such as straw can
increase nitrogen in the soil, thus high nitrogen
content certainly increases the rate of photosynthesis
hence the results of photosynthesis is in the form of
more starch produced which are stored in the tubers.
This was in accordance with the statement of
Djunaedi (2009) which stated that adding organic
matter (bokashi) to the soil can increase the content
of organic matter and soil nutrients. This was because
the more bokashi fertilizer doses are given, the N
contained in bokashi fertilizer is also received more
by the soil. N element is a very important nutrient
because it is the most needed element for plant
growth. The use of plastic mulch showed a softer
tuber hardness level than the use of straw mulch but
harder than without mulch, this was due to the low
water content in the tuber.
3.3 Tuber-flesh Beta Carotene Content
Beta Carotene is a major component of provitamin A
in foods containing carotenoid compounds (van
Jaarsveld et al., 2005). Beta Carotene is an ingredient
that forms vitamin A in the body, which plays an
important role in maintaining a healthy sense of sight
(Hasyim and Yusuf, 2008). According to van
Jaarsveld et al., (2005) pro-vitamin A sources are in
yellow and orange fruits and vegetables and dark
green leaf vegetables. The orange tuber-flesh sweet
potato is one source of beta-carotene (Eluagu and
Oniwamo, 2010).
Table 3: Beta-carotene content in three sweet potato clones
using mulch.
Clone
Beta Carotene (mg/100 g)
Yellow flesh-tuber (B1)
6,72 ab
Purple flesh-tuber (B2)
5,66 b
Orange flesh-tuber (B3)
8,45 a
Mulch
Without Mulch ( A0)
7,55
Plastic Mulch (A1)
7,48
Straw Mulch (A2)
5,80
Description: Numbers followed by the same notation on
the same line showed no significant
difference according to Duncan's Multiple
Range Test at the level of 5%.
The highest beta-carotene content was found in
orange-fleshed sweet potato clones of 845 mg/100 g
and the lowest was in purple-flesh sweet potato
clones of 566 mg/100 g (Table 2). Sebuliba et al.
(2001) stated that the beta-carotene content contained
in orange tuber-flesh cultivars was higher than yellow
and white.
The use of mulch also had no significant effect on
beta-carotene content in the tubers. Sweet potatoes
cultivated without using mulch had the highest tuber
beta-carotene content compared to sweet potatoes
which are cultivated using mulch. This was allegedly
because the content of beta carotene in tubers is
influenced by environmental factors, especially the
availability of water. Treatment without the use of
mulch tends to cause lower groundwater content
compared to the use of mulch. Masango (2014)
research also showed that watered sweet potato plants
every day tended to have lower beta carotene content
than sweet potatoes which were not watered.
3.4 Tuber-flesh Anthocyanin Content
Sweet potato anthocyanin levels vary, depending on
the intensity of purple color on the tuber-flesh. The
darker the purple color of the tuber, the higher the
level of anthocyanin (Ginting and Utomo, 2011). The
data in Table 4 showed that the highest anthocyanin
content was found in purple flesh sweet potato clones
which were 10.46 mg/100 g and the lowest was in
yellow flesh sweet potato clones of 3.73 mg/100 g.
Friedman and Levin (2009), stated that the color of
ICONART 2019 - International Conference on Natural Resources and Technology
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sweet potato flesh is influenced by the content of
beta-carotene and anthocyanin. Orange-flesh sweet
potato is rich in beta carotene sources, while purple-
flesh sweet potato is rich in anthocyanins and
phenolic compounds. The difference in anthocyanin
contents can also be caused by the season and
growing environment of the plant (Damanhuri 2005)
which affects the intensity of tuber color.
Anthocyanin accumulation is driven by
environmental factors such as light, temperature,
nitrogen sources, pathogen attacks and some growth
regulating substances such as cytokinin, gibberellic
acid (GA) and ethylene (Kim and Kim, 2010).
Table 4: Anthocyanin contents in three sweet potato clones
with the use of mulch.
Anthocyanin (mg/100 g)
3,73
10,46
5,86
7,72
6,55
5,79
The data in Table 4 also showed that the use of
mulch did not affect the anthocyanin contents in the
tuber. Anthocyanin content in tubers is influenced by
the type of clones and environmental factors,
especially the soil water content. Sweet potato plants
that were not given mulch produce tubers with the
highest anthocyanin content compared to other
treatments. Research results from Oktavidiati et. al
(2013) also showed that anthocyanin content in Red
Meniran leaves (Phyllanthus urinaria L.) with
drought stress treatment to 25% field capacity higher
than 100% groundwater content and 75% field
capacity. This was thought to be related to the
function of anthocyanin as an antioxidant whose
activity increases when plants experience
environmental stress.
4 CONCLUSIONS
The results showed that 3 sweet potato clones which
were commonly planted in Binjai City had various
levels of water and various content of beta-carotene
and anthocyanins. The use of mulch in sweet potato
planting systems in this research significantly
affected the water content and hardness of sweet
potato tuber but did not significantly affect the levels
of beta carotene and anthocyanin in the tuber.
REFERENCES
Antarlina, S. S., 1997. Characteristics of sweet potato as
flour for the cake making. p. 188-204. In Budijanto, S.,
F. Zakaria, R. Dewanti-Hariyadi, B. Satiawiharja (Ed).
In Proceedings of the National Food Technology
Seminar in Denpasar 16-17 July 1997. PATPI-Republic
of Indonesia.
Ameny, M. A., Wilson, P. W., 1997. Relationsip between
hunter color value and β-carotene contents in white
flesh african sweet potatoes (Ipomoea batatas Lam.).
J.Sci. Food and Agric. 73: 301-306.
Afandi, A. 2013. The changes of water content and soi;
temperature due to the giving of organic mulch in
pineapple plantations PT Great Giant Pineapple
Terbanggi Besar Central Lampung. Tropical
Agriculture Journal. ISSN 2337-4993 Vol. 1, No. 2:
213 - 218.
Badan Serifikasi Nasional. 1998. Sweet potato SNI (SNI 01-
4493:1998). National Standardization Agency. Jakarta.
11 Pages
Djunedi, A. 2009. The effect of type and dosage of bokashi
fertilizer on growth and production of long bean (Vigna
sinensis L.). Faculty of Agriculture, University of
Trunojoyo. Madura.
Elisabeth, D. A. A., Widyaningsih, M. A., Kariada, I. K.,
2007. Utilization of sweet potato tubers as raw material
for making ice cream. Bali Institute of Agricultural
Technology (BPTP). Pp. 1-7.
Eluagu, E. N., Onimawo, I. A. 2010. Effect of processing
on the mineral composition and antinutritional factors
of orange fleshed sweet potato (Ipomoea Batatas L.
Lam.) Flours. Electronic Journal of Environmental,
Agricultural and Food Chemistry. 9(6): 1000-1005.
Friedman, M., Levin, C. E. 2009. Analysis and biological
activities of potato glycoalkaloid, calystegine alkaloids,
phenolic compounds and anthocyanin. In: Advances in
potato Chemistry and technology. Singh, J. and Kaur,
L. (Eds.). Academic Press, Elsevier Inc., New York. pp.
127-161.
Gillespie, T. J., Swanton, C. J., Wagner, C. S. 1992. The
effect of organic mulches on soil moisture and crop
growth. Jurnal of Technology Evaluation and
Development: 56-58.
Ginting, E., Jusuf, M., Rahayuningsih, S. A. 2008. The
physical, chemical and sensory properties of eight
yellow/orange sweet potato clones which rich of beta
carotene. Proceedings of the Legums and Tubes
Seminar.
Ginting, E., Utomo, J. S., Yulifianti, R., Jusuf, M. 2011. The
potential of purple sweet potato as a Functional Food.
Food Crop Science and Technology, 6(1), 116-138.
Ginting, E., Yulifianti, R., Jusuf, M., Mejaya, M. J. 2015.
Identification of physical, chemical, and sensory clones
of the anthocyanin-rich sweet potato expectations.
Food Crop Agriculture Research 34 (1)
Hasyim, A., Yusuf, M. 2008. Sweet potatoes rich of
anthocyanins, healthy food choice. Sinar Tani Edisi 20.,
26.
Morphophysiological Characteristics Analysis of Tuber from Multiple Sweet Potato Clones (Ipomea batatas Lamb.) with Mulching
Application
185
Husna, N. E., Novita, M., Rohaya, S. 2013. The
anthocyanin content and antioxidant activity of fresh
purple sweet potato and its processed products.
Agritech. 33(3):296-302
Kim, H. B., Kim, S. L., Koh, S. H., Seok, Y., Sung, G. B.,
Lee, K. G. 2010. The development of natural pigments
from mulberry fruits as a food additive. Paper
presented at the International Conference on
Neuraceutical and Functional Food in Denpasar, Bali
on 12-15 th October 2010
Listya, Ana, Sinly dan Satuhu, S. 2010. ntiradical activity
and beta carotene levels in honey honey and longan
honey. FMIPA Udayana University. Bukit Jimbaran
Masango, S., 2014. Water Use Efficiency of Orange
Fleshed Sweet Potato. University Pretoria.
Oktavidiati, E., Chozin, M. A., Ghulamahdi, M.,
Wijayanto, N., Darusman, L. K., Sunaryadi. 2013. The
growth and anthocyanin content of green meniran
leaves (Phyllanthus niruri L.) and red meniran
(Phyllanthus urinaria L.) at various soil moisture levels.
Health Journal of Health Research and Development
Agency 6 (1): 19-30
Prabhavat, S., Reungmaneepaitoan, S., Hengsawadi, D.
2008. Production of high protein snacks from ubijalar
(Ipomoea Batatas L.). Kasetsart Journal (Nat. Sci.)
(29): 131–141.
Purnomo. 1995. Water activity and its role in food
preservation. UI Press Jakarta
Sebuliba, J. M., Nsubuga, E. N., Muyonga, J. H. 2001.
Potential of Orange and Yellow Fleshed Sweet potato
Cultivars for Improving Vitamin A Nutrition in Central
Uganda. African Crop Science Journal. 9(10): 309-316.
Kusumaningtyas, R. K., Limantara, L. 2009. The
isomerization and oxidation of carotenoid compounds
in the oil palm fruit during productions of CPO.
Indonesian Journal of Chemistry, 9(1), 48-53.
Suwanto, E. P., Hapsari, Y. D. 2012. Study and Design of
Digital Penetrometers As Microcontroller Based
Material Consistency Test Equipment. Department of
Physics, Faculty of Mathematics and Natural Sciences.
Ten November Institute of Technology. Surabaya.
Rumbaoa, R. G. O., Cornago, D. F., Geronimo, I. M. 2009.
Phenolic content and antioxidant capacity of Philippine
sweet potato (Ipomoea batatas) varieties. Food Chem.
113:1133-1138.
Van Jaarsveld, P. J., Faber, M., Tanumihardjo, S. A.,
Nestle, P., Lombard, C. J., Benade, A. J. S. 2005. β-
carotene rich orange fleshed sweet potato improves the
vitamin a status of primary school children assessed
with the modified-relative- dose-response test.
American Journal of Clinical Nutrition, 81(5): 1080 –
1087.
ICONART 2019 - International Conference on Natural Resources and Technology
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