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Researchs on the sweet potato ( Ipomea batatas L.) behaviour under the soi
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 Volume 19(1), 79- 84, 2015
JOURNAL of Horticulture, Forestry and Biotechnology
www.journal-hfb.usab-tm.ro

Researches on the sweet potato (Ipomea batatas L.) behaviour

under the soil and climatic conditions of the South-West of
Romania
Dinu Maria1*, Soare Rodica2

1
University of Craiova, The Faculty of Agriculture & Horticulture, The Department of Horticulture and Food
2
Science, 13 A.I.Cuza Street, 200858 Romania; University of Craiova, Faculty of Agriculture &Horticulture,
Libertatii Street, no 19, 200583, Craiova, Dolj, Romania

*Corresponding author. Email: dinumariana@hotmail.com

Abstract This study aims to present the role of sweet potato (Ipomea Key words
batatas L.) in human alimentation, specifically to present two new cultivars
recently cultivated, their way of behaviour in the south-west of Romania, the sweet potato, cultivation,
biochemical composition of the tuberous roots and the productive potential of biochemical composition
this species.
The sweet potato is appreciated for its very high nutritional value,
both of the tubers and of the young aerial parts. The thickened roots rich in
carbohydrates, starch, minerals (Ca, Mn, Cu Fe, P, K) and vitamins (ß-
carotene, vitamin C, B6) can be used in various forms of meals: mashed
sweet potatoes, soups, fries, desserts. Considering the qualities of these
varieties, in The Didactic Research Station of the University of Craiova there
was studied the behaviour of two cultivars of sweet potato, Pumpkin and
Chestnut in terms of productive potential and biochemical composition, under
the conditions in the south-west of Romania.
Within the experiment there were made observations on the way of
plant growth: the number of stems in the bed, the average and total weight of
haulm and the total quantity of vegetal material. We also observed the
characteristics in terms of tuberous roots production, and the average number
of the tuberous roots per bed, their dimensions and weight. The water
content, the dry matter and soluble dry matter, the titratable acidity, the
starch, total sugar and vitamin C content were determined and the yield was
calculated. The study shows that the best productive performance was
recorded in the Pumpkin cultivar, 53.3 t/ha, and in terms of chemical
composition, the total sugar content and vitamin C content, the higher values
were recorded in Chestnut, 14.1 %, 14.6 mg/100 g FW respectively.
The results of our study should determine the development of certain
research activities at national multidisciplinary level which aim at improving
the production technology, the storage, the post-harvest and processing
technologies, and the quality of sweet potato and its value-added products.

The sweet potato (Ipomea batatas L.), or were carried out researches at the University of
American potato belongs to the Convolvulaceae family Agronomic Sciences and Veterinary Medicine
and it is original from South America; it is cultivated Bucharest by Ruxandra Ciofu and the collective of the
on large areas in China, India, Japan, in south-eastern vegetable growing subject matter. Two cultivars
Asia and in Africa. It is also cultivated in southern Victoria IANB and Crux were created (10).
Russia, the US, South America and even in the The sweet potato contains complex
Mediterranean areas of Europe. This species is among carbohydrates, especially simple sugars; the sweet
the most important food crop in the world with more potato glycemic index is quite high and it is therefore
than 133 million tonnes in annual production (2; 3). Its unsuitable for diabetics and overweight persons. The
culture can be found on all continents, in over 95 carbohydrate content is 20.1 g/100 g edible part of
countries with an area of over 9.5 million hectares, the which 16.0 g is starch and 4.2 g are soluble sugars. The
largest in China (22). proteins are in small quantities, as well as fats. Instead
It replaces completely the potato in the the fibres are quite abundant making the sweet potato
subtropical and tropical regions. In our country there suitable for those suffering from constipation.

79
Regarding the minerals, the American potato is rich in There are numerous studies which show that
potassium and magnesium. It has a high content of B6 the sweet potato leaves are rich in anthocyanins and
vitamin and a remarkable content of vitamin A (18). phenolic acids than most vegetables found on the
This species is appreciated due to the thickened roots market. These polyphenols have radical properties,
nutritional value, rich in carbohydrates, starch, mineral scavenging activity, antimutagenic activity, anticancer,
salts of potassium, calcium, phosphorus, magnesium, antidiabetes, and antibacterial activity, which may be
various organic acids, ß-carotene, vitamin E, C and A helpful for maintaining human health (8).
which can be used in various types of dishes (mashed The culture of sweet potato is very profitable
potatoes, soups, fries, desserts) (5). and encouraged in many countries. The tobacco
The rizoderm of the thickened roots has growers in eastern Kentucky found as an alternative the
different colours (white, cream, yellow, orange, pink, culture of sweet potato which is profitable and sought
red to purple.), and the pulp has shades of ivory, by consumers; the organic sweet potato is also
orange or purple-lilac (1; 3). The orange colour is currently produced in the state of Mississippi,
given by the high content of ß-carotene: 11,500 mg per especially used for baby food (20).
100g of product, compared with only 6 mg contained Because this culture is considered an
by potatoes, and even with 40% more than carrots. The important source of food security, with great potential
beta-carotene is converted by the human body into to alleviate hunger in many countries in Africa, the
vitamin A, with beneficial effects on the immunity State University of North Carolina will be funded by
enhancement, skin health and membranes lining the the Bill & Melinda Gates Foundation with over 12
nose, lungs and intestines. A sweet potato provides million dollars to conduct studies to improve the
about half of the necessary nutritional vitamin E and technology of this species (21).
contains significant amounts of other vitamins and In Romania, the sweet potato is almost
minerals. unknown by the population, the first investigations
A 100 g of sweet potato has the following were carried out since 1954, when it was brought into
nutritional quality: 105 kcal energy; 2.22 g proteins; the country and its behaviour was observed in specific
74.43% water; 14.43% starch; 3.48% total sugar; temperate climate conditions in our country and there
0.58% glucose; 1.10% cellulose. Due to the was established the technological sequences. The
biochemical composition and large production per unit researches have shown that the sweet potato can be
area (above 40 t/ha) it is a good source of food in many grown in Romania, especially on sandy soils in the
least developed countries with problems of nutrition south-west of the country (7). Also, the researches have
(14; 19). continued at the University of Agronomic Sciences and
According to the estimations of the Center for Veterinary Medicine Bucharest and they were
Science in the Public Interest, the nutritional value of conducted by Ruxandra Ciofu and the collective of the
sweet potato is more impressive than the one of vegetable growing subject matter (11;12).
common potato. In comparison to the latter, the sweet Also, this culture is well suited for sandy soils
potato has a much higher content of retinol equivalents, from south-west of the country but also on other soil
especially β-carotene. A study carried out in Uganda in types. Therefore, the objective of this paper was to
2012, which involved approx. 10,000 households study the behavior of two cultivars of sweet potato
showed that: "Only 10% of those who consume dark under pedoclimatic conditions from south-western
orange sweet potatoes suffer from vitamin deficit, Romania.
retinol equivalents, while 50% of those who consume
beige or pale yellow sweet potato have a significant Biological Material and Method
hypovitaminosis"; this is explained by the higher
content of β-carotene of dark orange sweet potatoes in
The experiment was placed in the didactic
comparison to the lighter ones (6).
area of the Faculty of Agriculture and Horticulture,
Due to its high content in starch, the sweet
University of Craiova, Romania, on a reddish brown
potato is used in the alcoholic beverages industry (the
preluvosoil. The biological material was represented by
spirits), food industry (flour of sweet potatoes, food
two sweet potato cultivars originating in South Korea
dyes) and in the textile industry to dye the fabrics and
which are named Pumpkin and Chestnut. The main
to obtain the paper. In South America, the juice of red
objective of the study was to test the behaviour of the
sweet potatoes, combined with lemon juice is used as a
two new cultivars introduced in Romania through a
dye for fabrics.
"Romanian-Korean Collaborative partnership for the
There is no waste from this variety. The leaves
sweet potato" which was signed between the Research
and young shoots are used in human food and the older
- Development Center for Agricultural Plants on Sands
ones for the animal feed. It can also be used for
Dăbuleni and Gyeongbuk Province FTA Committee
ornaments and landscapes due to the variety of colours
(GPFC) –South Korea.
of the leaves and variety of forms or it can remain on
The culture was formed by cuttings obtained
the soil as a green carpet, the plant growing as haulm.
by forcing the tuberous roots in greenhouses, which
were left two days after being removed from the

80
mother plants in ventilated rooms and then planted to precisely compare the various biochemical
without previous rooting, as it has been done before in components by reference to 100 g dry matter.
some tests in Romania. Regarding the soil, it should be The titratable acidity- the principle of the
sandy or loamy-sandy or allow good ventilation method is the titration with a NaOH 0.1N standard
because the roots need oxygen in order to develop. The volumetric solution in the presence of phenolphthalein
sweet potato does not support excessively humid soils. as indicator.
The cuttings were planted on June 15 on high The determination of total sugar content was
ridges of above 30 cm, at a distance of 70 cm between made by refractometry using the refractometer Delta
them and 40 cm between plants in rows resulting refractometer Bellingram Stanley DTD.
33,333 plants/ha. The vitamin C was determined by volume.
Regarding the culture technology there were The starch was determined polarimetrically using a
applied 2 fertilizations with complex fertilizer 20-20- Jasco P 2000 polarimeter and its content was reported
20 + micronutrients, 150 kg/ha, and the drip irrigation to the dry matter of the samples.
was performed in the case of moisture deficit. For
weed control in the early stages of vegetation there was
Results and Discussions
applied manual hoeing, after that the vegetative growth
of sweet potatoes led to the soil cover, between plants
and interventions were no longer needed. Also, 2 The variability of climate in the south-west of
treatments were performed against the diseases attack Romania where summers are dry and hot offers
with Topsin alternating with Bravo and for pests, with favourable conditions for growing the sweet potatoes.
Actara alternating with Calypso. In Romania, the sweet potato crop is at the beginning
After harvesting the roots, they were washed and could be a great alternative enriching the range of
and placed in storage areas. less cultivated species.
The experiment was arranged in randomized In the experiment located in the
blocks, in four replications. There was taken as control didactic field of the vegetable growing subject matter,
the cultivars average. At harvest, there were made observations and measurements on the vegetative
observations on the morphological characteristics of growth of sweet potato (table1) for each cultivar were
plants: the number of haulms in the bed, the average made on October 20. Thus, the Pumpkin cultivar
and total weight of the haulm and the total quantity of recorded 8.5 stems/bed, which had a total mass of 1230
plant material, reported in tonnes per hectare. There g and the average weight per each stem of 145 g, while
were also observed the production characteristics: the the average number of stems of the Chestnut cultivar
average number of the tuberous roots per plant, their was smaller, 7.8 with a total mass of 800 g and an
dimensions and weight. There was determined the average weight of 102.5 g/stem. The Pumpkin cultivar
water content, the S:U:T and S.U.S, titratable acidity, plants were more vigorous with strong developed
starch, total sugar and vitamin C content for the two stems, which reached a production of 41 t/ha. The
cultivars and the yield was calculated. Chestnut cultivar haulms are less developed and the
The data were interpreted statistically and the foliar system is smaller and less developed as well as
analysis of variance was performed using ANOVA. the total production of stems, which was of 26.6 t/ ha
The roots moisture was determined by the (Table 1). Some authors (Zihin et all., 2011)(17)
gravimetric method, in order to calculate the S.U.T and reported the stem length between 332.2 cm and 405.7
cm and stem number / plant, between 6.5 and 14.1.

Table 1
The influence of cultivar on plant growth of sweet potato
(average values)
Morphological characteristics:
Cultivar No./bed Total weight g/bed Average weight t/ha
g/stem
Pumpkin 8.5 1230 145 41.0
Chestnut 7.8 800 102.5 26.6

All this mass vegetative production in polyphenols, phenolic acids and anthocyanins, in
Romania is used in animal feed while in countries with relation to many vegetables. The leaves of this species
a tradition of the sweet potato crop it is used in human contain at least 15 anthocyanins biologically active that
food, prepared in various forms or in industry as dye have a significant drug amount for certain human
(4). diseases and can be also used as natural food dyes.
The previous experiments have shown that the These polyphenols have properties to capture the free
leaves of sweet potatoes have a high content of radicals, antimutagenic, anticancer, antidiabetic and

81
antibacterial activity that can be useful for maintaining process was heavier and this thing was observed in the
and promoting the human health (8). crop.
The thickened roots had a very uneven For the studied sweet potatoes cultivars, the
development because during the plant vegetative average number of thickened roots per storage was 4.0
development (July-August- September) the amount of for Pumpkin and 5.1 for Chestnut. The average weight
rainfall in the area of culture was quite big but of roots of the Pumpkin cultivar was 400 g and 210 g
unevenly distributed, thus disfavouring the normal for the Chestnut cultivar (Table 2). In other studies
development of thickened roots and favouring the (Zihin et all., 2011)(17) have been reported values for
vegetative plant growth. Periodically we entered into root number / plant from 5.1 to 11.5, and the weight of
the culture and the plants were moved in order to not storage for root/plant from 504.8 to 738.8 g.
form adventitious roots, but during the rains this

Table 2
The influence of cultviar on the main productivity characters

Productivity characters (medium values)

Cultivar
Number of Weight of storage Weight of storage
storage root /plant (g) root
root /plant (g)
Pumpkin 4,0 1600 400
Chestnut 5,1 1071 210

The sweet potato production for the two The Chestnut cultivar presented lower yields
cultivars ranged between 35.6 t/ha and 53.3 t/ha, with compared to the control plant, to the average of the two
an average per experiment of 44.5 t/ha, a relatively variants, the difference in production being of -8.9 t /
high level, given the conditions of culture, relatively ha which is distinct significantly negative (Table 3).
low thermal regime and high rainfall during the growth The two studied cultivars were tested in the
and roots formation. According to the analysis of Research - Development Center for Agricultural Plants
variance, considering as control the cultivars average, on Sands Dăbuleni and they behaved very well,
the Pumpkin cultivar had the highest production, the obtaining productions of over 30 tonnes/ha.
difference in yield being of 8.8 t/ha; thus it was
statistically assumed at the distinct significant levels.

Table 3
The production of sweet potato for the studied cultivars in Banu Maracine DC

Cultivar Production ± Difference from Signification

t/ha % the control
Pumpkin 53.3 119.7 8.8 xx
Chestnut 35.6 80 -8.9 00
Average of cultivars 44.5 100.00 - -
(control)

DL 1%=5.24 t/ha; DL 5%=3.16t/ha; DL 0.1%= 9.81 t/ha

The sweet potato tubers are mainly a source of 70.05%, which was higher for the Chestnut cultivar
energy due to their high content of carbohydrates, and which is correlated with the content of the dry
which is 80-90% of the dry weight. These matter (32.90 and 29.95 respectively) values sustained
carbohydrates consist of starch, sugar and small also by other authors (13;16;18). Soluble dry matter
amounts of pectin, hemicelluloses and cellulose (9). had higher values for the Chestnut cultivar that, overall,
For the biochemical analysis of the two recorded higher values for all the components than for
cultivars of sweet potato there were taken samples the Pumpkin cultivar. In the literature, the dry matter
from each cultivar, from each repetition (Table 4). content of fresh tubers ranged from 30% to 45%,
Thus, the water content varied between 67.10% and values sustained also by other authors (13; 18).

82
 Table 4
The biochemical composition of the tuberous roots of sweet potato depending on cultivar
Cultivar Water Dry Soluble Titratable Total Vitamin C
(%) matter dry acidity (%) sugar (mg/100 g
Starch %
(%) matter (%) FW)
(%)
Pumpkin 67.10 32.90 11.5 0.28 31.94 13.2 12.9
Chestnut 70.05 29.95 13.1 0.26 32.00 14.1 14.6

The titratable acidity had values ranging - the best yield was produced by the Pumpkin
between 0.28 and 0.26% and the starch content was cultivar, 53.3 t/ha;
above the values quoted in the literature, namely - in terms of chemical composition, the
31.94% for Pumpkin and 32.0% for Chestnut (14). content of total sugar and vitamin C were higher in the
The total sugar had a value of 13.2% for Chestnut cultivar, of 14.1% and 14.6 mg/100 g FW .
Pumpkin and 14.1% for Chestnut, values that have The requirements of the sweet potato for the
been cited by other authors in different studies, (15; 16) vegetation factors are met especially in the south-
existing American varieties containing over 38% (18). western part of Romania where this species can be
The sugar content can be highly variable, usually successfully cultivated.
between 1 and 12% DM, but some American varieties
contain up to 38% DM of sugars. The sugar
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