Adaptability and acceptability of new orange-fleshed sweetpotato varieties in selected areas of Eastern and Central zones of Tanzania

Abstract

Orange-fleshed sweetpotato
(OFSP) has been earmarked to be among foodbased
approaches in providing cheap source
of beta-carotene a precursor of Vitamin A.
Orange coloration intensity in sweetpotato
roots correlates positively with the amount
of beta-carotene available. In Tanzania,
sweetpotato is produced almost entirely for
home consumption and majority of popular
varieties are either white or yellow- fleshed,
which don’t qualify to provide enough
vitamins to meet the daily requirements.
Majority of sweetpotato growers are resource
poor with limited access to expensive sources
of Vitamin A. Severe deficiency of Vitamin A
has been reported to contribute to about 60
percent mortality rates for prescholers
(children aged under 5 years) and pregnant/
lactating mothers in South Asia and sub
Saharan Africa. In Tanzania, production and
utilization of OFSP is limited, hence there was
a need to test the adaptability and
acceptability of the newly introduced varieties
by farmers to ensure wide acceptance hence
increased utilization. Twenty improved
orange fleshed varieties introduced from CIP
in 2001 were evaluated at Kibaha (lowland
warm sub-humid) and Hombolo highland
warm semi-arid) research stations. Two local
checks were included. At harvest, farmers
were invited to conduct the acceptability
studies so as to capture the consumer-desired
qualities. Varieties Tainung-65 (440215) and
Japon Tresmesino (420009) produced
significantlyhigh yields at both sites. Carrot-
C (local check) gave the least yields. All
varieties tested showed mild symptoms of
virus disease. Results on farmer’s assessment
revealed that, among the varieties, Tainung-
65, Jonathan, Zapallo and Centennial had
generally higher acceptance levels. Others
were rejected due to low dry matter, inability
to produce enough planting materials
especially during the dry season and some
due to low yields. Varieties Tainung 65,
Jonathan, Zapallo and Centenial have
therefore been selected for on-farm testing.

Full text

Proceedings of the 13th ISTRC Symposium, 2007
pp. 737 - 745
Adaptability and acceptability of new orange-fleshed
sweetpotato varieties in selected areas of Eastern and
Central zones of Tanzania
Masumba E.1, Kapinga R.2, Tollan S.M.1, Mary o1, Yongolo1 and Kitundu C.D.3
1Root/tuber Crops Research Programme, SRI-Kibaha, P. O. Box 30031, Kibaha, Tanzania.
2International Potato Center (CIP), Box 22274, Kampala, Uganda. 3Hombolo Agricultural Research
Institute, P. O. Box 299, Dodoma, Tanzania
Abstract. Orange-fleshed sweetpotato
(OFSP) has been earmarked to be among food-
based approaches in providing cheap source
of beta-carotene a precursor of Vitamin A.
Orange coloration intensity in sweetpotato
roots correlates positively with the amount
of beta-carotene available. In Tanzania,
sweetpotato is produced almost entirely for
home consumption and majority of popular
varieties are either white or yellow- fleshed,
which don’t qualify to provide enough
vitamins to meet the daily requirements.
Majority of sweetpotato growers are resource
poor with limited access to expensive sources
of Vitamin A. Severe deficiency of Vitamin A
has been reported to contribute to about 60
percent mortality rates for prescholers
(children aged under 5 years) and pregnant/
lactating mothers in South Asia and sub
Saharan Africa. In Tanzania, production and
utilization of OFSP is limited, hence there was
a need to test the adaptability and
acceptability of the newly introduced varieties
by farmers to ensure wide acceptance hence
increased utilization. Twenty improved
orange fleshed varieties introduced from CIP
in 2001 were evaluated at Kibaha (lowland
warm sub-humid) and Hombolo highland
warm semi-arid) research stations. Two local
checks were included. At harvest, farmers
were invited to conduct the acceptability
studies so as to capture the consumer-desired
qualities. Varieties Tainung-65 (440215) and
Japon Tresmesino (420009) produced
significantlyhigh yields at both sites. Carrot-
C (local check) gave the least yields. All
varieties tested showed mild symptoms of
virus disease. Results on farmer’s assessment
revealed that, among the varieties, Tainung-
65, Jonathan, Zapallo and Centennial had
generally higher acceptance levels. Others
were rejected due to low dry matter, inability
to produce enough planting materials
especially during the dry season and some
due to low yields. Varieties Tainung 65,
Jonathan, Zapallo and Centenial have
therefore been selected for on-farm testing.
Introduction
Sweetpotato (Ipomoea batatas. Lam) is grown
throughout Tanzania and is the third most
important root and tuber crop after cassava
(Manihot esculenta) and round potato
(Solanum spp.). The crop occupies
approximately 14 percent of total arable land
of the farms surveyed (Kapinga et al., 1995).
Consumption of sweetpotato is mostly by
boiling; roasting and deep-frying of the roots
and the leaves are blanched and used as
vegetable.
Vitamin A deficiency (VAD) is the world’s
most common cause on child blindness
(Mukherjee et al., 2002). WHO estimates 228
million children affected sub clinically and
500,000 children become partially/totally blind
every year as a result of Vitamin A deficiency.
Low et al. ( 2001) reported that, in Sub Saharan
Africa (SSA) and Asia, there are severe
deficiency of Vitamin A leading to high fatality

Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
738
rates of 60 percent for preschoolers (children
under 5 years of age) and pregnant/lactating
mothers. In SSA, estimates of VAD children
aged 5 range from 24% to 70% (Harvey and
Taylor, 2003).
Promotion of the consumption rate of
OFSP at community level is a food-based
approach that aims at combating Vitamin A
deficiency especially for women and children.
Most of sweetpotato growers are resource
poor, therefore consume imbalanced diets.
Among Vitamin A rich foods, OFSP provides
a cheap source of Vitamin A (Low et al., 2001).
Orange coloration intensity in sweetpotato
root flesh indicates its level of β-carotene (van
Jaarsveld, 2003).
Most of sweetpotatoes grown by farmers
are white fleshed. Experience indicates that,
most of the orange-fleshed sweetpotato
varieties currently grown by farmers have low
root yields accompanied by low dry matter
contents (Mwanga et al., 2003b). High dry
matter content is among the major criteria used
by farmers in the selection of sweetpotato
varieties in Tanzania; especially in the Eastern
zone farming communities (Masumba et al.,
2003). Therefore there was a need to introduce
OFSP varieties adapted to Tanzania conditions
and also acceptable to consumers.
Objectives. The following objectives were
targeted:
• To introduce and evaluate orange-fleshed
varieties.
• Assess consumer acceptability of the
introduced orange fleshed varieties.
• Assess the adaptability of the introduced
varieties in the two agro-ecologies
(lowland warm sub humid and highland
warm semi-arid areas).
• To increase the diversity of OFSP to
combat Vitamin A deficiency at community
level.
Materials and Methods
Tested varieties. Twenty OFSP varieties
including the local checks namely Mayai and
Carrot-C were used ( Table 1).
Research locations. The varieties were
evaluated on station for their general
performance in terms of their virus reaction,
root yield and adaptability. Two different agro-
ecologies were identified and used for rapid
evaluations of the introduced varieties. These
were the lowland warm sub-humid (Kibaha),
about 107 meters above sea level with sandy
clay loam soils. It is characterized by a weak
bimodal pattern of rainfall of an average of
970mm per annum. The second was a
highland warm semi-arid (Hombolo) area
about 1070 meters above sea level with reddish
loamy soils. This area experiences a
Table 1: Twenty orange-fleshed varieties of sweet potato
introduced from International Potato Center (CIP), Kenya
in 2001.
Variety CIP number
1. Tainung No. 65 440215
2. Tainung No. 64 440189
3. W-123 440018
4. W-151 440005
5. VSP-3 440287
6. VSP-4 440228
7. Jewel 38 56638
8. Jewel 31 440031
9. TIB 440060
10. Resisto 187017
11. Salyboro 187017
12. Excel 440016
13. BP-SP-2 440293
14. Kandee 440140
15. Zapallo 420027
16. Jonathan 420014
17. Julian 440141
18. CN 317 440090
19. Japon tresmesino 420009
20. Nemaneje -
21. Centenial 440122

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Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
monomodal rainfall pattern with an average
rainfall of about 655mm per annum.
Experimental design. A replicated preliminary
yield trial was established during the long
rains in April 2002 (Kibaha) and January 2003
(Hombolo). This is the common sweetpotato
growing season in the respective areas. Plot
size was 1.0m x 6.0m and plants spaced at 0.3m
as intra-row spacing (i.e., 20 plants per ridge,
two/four rows per variety).
Consumer acceptance by farmers. A total of
26 (Eastern zone) and 30 (Central zone)
sweetpotato farmers were invited for
participatory sweetpotato variety selection at
Kibaha and Hombolo research stations,
respectively. They were involved in the
assessment of the post harvest attributes of
the varieties including appearance, taste,
mealyness, fibrousness and general
acceptability. Clones were assessed by
individual farmers using a subjective scale
(1=very poor, 2=poor, 3=moderate, 4=good
and 5=excellent) (Kapinga et al., 2000). By the
use of matrix ranking procedure mean scores
were ranked. Farmer opinions on individual
clones were computed into frequencies.
Scores of the clones were compared using
means.
Data collection and analysis. Data collected
included plant establishment, virus scores,
foliage and root yield (number, weight of the
storage roots and dry matter content). A CIP
scoring method was adopted and data
subjected to the Analysis of Variance
(ANOVA) using Mstat-C package.
Results and Discussions
Plant establishment and sweetpotato virus
disease reaction. Generally establishment rates
at Kibaha were higher with the average of 97.4
% as compared to Hombolo 75.5% (Table 2),
probably as a result of semi arid condition the
latter location experiences. At Kibaha all the
varieties had good establishment rate of
above 90.0% except for Julian (440141)
(80.0%). The same variety Julian could not
be established at Hombolo because it dried
off after planting.
Reaction to sweetpotato virus diseases.
Results on severity scores for sweetpotato
virus disease ranged between class 2 (mild
symptoms on a few plants) and 4 (mild
symptoms on many plants, stunting of many
plants). Generally, Salyboro and the two local
checks (Carrot-C and Mayai) had the lowest
scores displaying its mild resistance to the
disease (Table 2). The rest of the introductions
succumbed to the disease. Kibaha site was
however less affected by SPVD than
Hombolo. Virus pressure in the region, has
slowed down the uptake and promotion of
OFSP as noted earlier studies (Kapinga et al.,
1995; Kapinga et al., 2003; Mwanga et al.,
2003a) and Laurie et al., 2003). CIP however
in collaboration with other research
organizations has developed new varieties
high in dry matter content and beta-carotene
with good resistance to sweetpotato virus
diseases. These varieties will be introduced
in Tanzania soon ( Kapinga et al 2003,
Mwanga et al 2003b).
Plant vigour and foliage weight. Most of the
varieties had intermediate vigour (class 3).
Tainung 65 had the highest plant vigour (class
5 for Hombolo site) followed by the local
checks Mayai and Carrot-C (Table 3).
Hombolo site gave the lowest yields because
of the dry weather as compared to Kibaha
site. The amount of rain for the two cropping
seasons at Kibaha was abnormally low and
erratic.
Root yield and dry matter content. High root
yields is among the best criteria that farmers
base on in the selection of crop varieties.
Average root yields that reported by the
Tanzanian Ministry of Agriculture and Food
Security are as low as 2.0 t/ha. In this study,
at Kibaha site, almost 50% of the total
introduced varieties produced higher yields
than the local varieties (Table 4). Varieties
Salyboro, Japon, Tresmesino, Tainung 65 and

Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
740
VSP 65 gave higher yields at both sites.
Majority of the tested varieties had high dry
matter contents (beyond 30% at both sites).
Varieties Tainung 64, Nemanete, W-123, CN-
317 and Centenial although low yielders gave
higher dry matter contents.
Consumer acceptability by farmers:A good
number of varieties (55%) tested at both
locations were highly accepted by consumers
for good taste and other root attributes
(Tables 5 and 6). Majority were appreciated
for being “dry” as the local ones.
Conclusion and implications
The results showed that OFSP varieties were
accepted at both trial sites in Tanzania
indicating wide adaptability and acceptability.
Varieties Salyboro, Tainung 65, Japon
Tresmeniso, Jonathan, Zapallo, Excell and
Kandee are doing well even in other parts of
Tanzania, Kenya, South Africa, and
Mozambique ( Kulembeka et al., 2003;
Kapinga et al., 2003; Laurie et al., 2003). These
have not been successful in the Lake Victoria
Crescent of Uganda because of the high virus
pressure ( Mwanga et al., 2003). This implies
that careful recommendations should be made
taking these exceptional cases into
consideration. While research continues on
breeding to combine multiple resistances to
stress factors, most of the introduced varieties
can be promoted in low virus pressures. Also
breeding programs should target to raise
populations using African landraces or
improved African germplasm that are already
adapted to various stresses. Examples are
Table 2: Plant establishment of orange fleshed sweet potato varieties and their reaction to virus diseases at Kibaha and
Hombolo stations , Tanzania (2002/2003).
Variety/clone CIP number Plant establishment (%) Sweetpotato virus disease evaluation
Kibaha Hombolo Kibaha Hombolo
Tainung 64 440189 100.0 78.3 2 4
Jonathan 420014 97.5 76.3 4 4
Salyboro 187017-1 100.0 70.9 2 2
Centenial 440112 92.5 61.6 2 4
W-123 440018 - 73.4 3 4
W-151 440005 92.5 3 4
Zapallo 420027 92.5 79.1 2 4
Jewel 31 440031 100.0 84.0 3 4
VSP-4 440228 97.5 68.9 4 4
Nemanete - 100.0 86.4 2 4
Kandee 440140 100.0 83.4 3 4
CN 317 440090 97.5 26.5 3 4
Tainung 65 440215 100.0 85.3 2 3
VSP-3 440287 97.5 72.5 4 4
TIB 440060 100.0 82.8 4 4
Jewel 38 56638 100.0 80.8 3 4
Resisto 440001 97.5 65.9 3 3
Excel 440016 100.0 81.0 2 4
Japon Tresmesino 420009 100.0 84.0 2 3
Julian 440141 80.0 - 2 -
Carrot-C Local check 100.0 73.8 2 2
Mayai Local check 100.0 95.0 2 2
SPVD scores: 1= No visible symptoms; 5= Completely attacked by virus.

741
Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
successful programs in South Africa, Zambia
and Uganda. The sweetpotato breeding and
evaluation program in South Africa has been
very effective. In South Africa 21 improved
cultivars and lines, of which 14 were
developed in South Africa, were found to be
acceptable to resource-poor farmers and
recommended for on-farm testing (Laurie et
al., 2003). In Uganda, variety Ejumula (a local
landrace) and SPK 004 (an improved variety
with an origin in Kenya) have widely been
accepted by farmers and processors for their
high yields and dry matter contents (Mwanga
et al., 2003b).
For this particular study all varieties
selected for high root yields, dry matter
contents plus consumer acceptance have
been advanced in adaptability studies under
diverse agro-ecologies. In these sites
multiplication at primary sites have been
initiated for the continuous supply of clean
healthy planting materials.
References
Harvey, P. W. and T.M. Taylor 2003. Global
and regional status of Vitamin A: global
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Table 3: Plant vigour and foliage weights of the evaluated varieties of orange-fleshed varieties of sweet potato at Kibaha
and Hombolo, Tanzania in 2002/3 and 2003/4.
Variety/clone CIP number Plant vigour Foliage weight (t/ha)
Kibaha Hombolo Kibaha Hombolo
Tainung 64 440189 3 3 7.7 5.1
Jonathan 420014 3 2 10.0 4.5
Salyboro 187017-1 3 3 11.7 5.0
Centenial 440112 3 1 9.3 1.2
W-123 440018 3 2 - 3.3
W-151 440005 3 — 12.0 -
Zapallo 420027 3 3 11.0 5.0
Jewel 31 440031 3 3 10.7 4.7
VSP-4 440228 3 3 13.0 4.8
Nemanete - 2 3 6.0 5.5
Kandee 440140 3 2 4.3 3.1
CN 317 440090 2 1 6.7 1.3
Tainung 65 440215 3 5 15.3 5.2
VSP-3 440287 3 3 12.3 4.5
TIB 440060 3 3 6.0 1.9
Jewel 38 56638 3 2 4.0 2.5
Resisto 440001 2 3 3.0 2.0
Excel 440016 3 3 7.7 3.9
Japon Tresmesino 420009 3 3 14.0 4.6
Julian 440141 2 - 2.7 -
Carrot-C Local check 3 4 9.0 6.1
Mayai Local check 4 4 11.0 11.5
Mean 8.9 4.3
LSD 0.05 3.1
Vigourness: 1= Very poor; 5= Very vigour

Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
742
Kapinga et al, 2003, Kapinga, R., Zhang, D.,
Lemaga, B., Andrade, M., Mwanga, R.,
Laurie, S., Ndolo, P., Kanju, E. (2003).
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Table 4: Yield performance and dry matter contents of orange-fleshed sweet potato varieties at Kibaha and Hombolo
sites, Tanzania (2002-2003).
Variety CIP number Root yield (t/ha) Dry matter content (%)
Kibaha Hombolo Kibaha Hombolo
(2002) (2003)
S L Total S L Total
Tainung 64 440189 1.0 7.7 8.7 0.6 2.0 2.6 27.3 35.3*
Jonathan 420014 1.0 10.0 11.0 0.2 1.1 1.3 30.6* 30.7*
Salyboro 187017-1 2.7 11.7 14.4** 1.8 4.0 5.8** 30.7* 30.7*
Centenial 440112 2.0 9.3 11.3** 0.1 0.5 0.6 30.6* 30.6*
W-123 440018 - - - 0.1 0.5 0.6 40.8* 40.2*
W-151 440005 3.3 12.0 15.3** - - - -
Zapallo 420027 2.0 11.0 13.0** 0.6 1.9 2.5 25.6 25.7
Jewel 31 440031 2,7 10.7 13.4** 0.8 1.0 1.8 30.5* 30.6*
VSP-4 440228 2.7 13.0 15.7** 0.3 1.6 1.9 28.7 28.6
Nemanete - 2.0 6.0 8.0 0.4 0.8 1.2 37.5* 37.5*
Kandee 440140 4.7 4.3 9.0 0.6 1.1 1.7 30.7* 28.2
CN 317 440090 5.0 6.7 11.7** 0.3 0.7 1.0 28.2 30.7*
Tainung 65 440215 3.0 15.3 18.3** 0.8 7.8 8.6** 22.8 28.2
VSP-3 440287 3.0 12.3 15.3** 0.3 2.7 3.0** 28.0 28.2
TIB 440060 2.3 6.0 8.3 0.4 2.3 2.7** 30.6* 30.6*
Jewel 38 56638 1.0 4.0 5.0 1.0 2.3 3.3** 23.4 23.6
Resisto 440001 4.0 1.0 5.0 0.5 2.6 3.1** 27.5 27.5
Excel 440016 1.0 7.7 8.7 0.6 3.9 4.5** 42.2* 21.0
Japon Tresmesino 420009 1.7 14.0 15.7** 0.3 3.3 3.6** 27.6 27.5
Julian 440141 2.3 2.7 5.0 - - - 36.3* -
Carrot-C Local check 1.7 9.0 10.7 - - - 34.5* -
Mayai Local check 1.3 11.0 12.3* 0.6 0.9 1.5 36.6* 37.9*
Mean 2.4 8.80 11.2 0.5 2.1 2.6 31.0
CV (%) 28.4 61.6
LSD 0.05 1.0 1.9
S- Small, L-Large * Selected for high dry matter contents** Selected for high yields.
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Kapinga, R. E., P.T. Ewell, S.C.Jeremiah, and
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Tanzanian sweetpotato varieties and their
associated acceptable qualities by end-

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Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
Table 6: Farmers’ assessment of cooked roots of OFSP varieties tested at Hombolo Station, Central Tanzania
(2002/3).
Variety Scores
Appearance Taste Mealyness Fibrousness Overall acceptability
Excel 3.7 2.9 1.9 2.9 2.8
Jonathan* 3.9 3.9 3.1 4.3 3.8
Jewel 3.3 3.7 2.7 3 3
Zapallo * 3.9 3.7 3.1 4.4 3.6
Centenial* 3.9 3.8 3 3.8 3.8
VSP-4 3.6 3.1 2.8 3.7 3
Japon Tresmesino* 3.6 3.8 2.9 3.7 3.8
W-123* 3 3.4 2.7 3.9 3.3
Jewel 38 3.7 3.2 2.6 3.1 3
TIB* 3.5 3.8 3.1 3.2 3.3
CN 317 3.4 3.2 2.7 3.3 3.2
Kandee* 4.1 3.9 3.1 3.6 3.8
Nemanete 2.8 3.1 3.3 3.4 2.8
Salyboro 3.2 3.4 3.3 3.8 3.2
Tainung 64* 3.7 4 2.6 3.3 3.5
VSP 3* 4 4.1 3.2 4 3.9
Resisto 3.2 3.2 2.8 3.2 3
Tainung 65* 4.2 4.2 3.4 4.4 4.1
Mayai* 2.8 3.4 3.4 3.3 3.3
N= 30; Scores: 1 = Very bad, 2 = Bad, 3 = Moderate, 4 = Good, 5 = Very Good
*Selected varieties for further adaptability studies and on-farm evaluation and promotion
Table 5: Farmers assessment of cooked roots of OFSP varieties tested at Kibaha station, Tanzania ( 2002/03)
Variety Scores
Appearance Taste Mealyness Fibrousness Overall acceptability
Excel 2.9 3 2.8 4.5 3.2
Jonathan * 3.4 3.3 2.7 3.7 3.7
Jewel * 3.4 3.4 2.8 3.8 3.7
Zapallo* 2.7 3.7 3.1 3.6 3.4
Centenial 3.3 3.4 2.8 3.5 3.2
VSP-4 3.1 2 2 3 2.4
Japon Tresmesino 2.5 3.1 2.5 3.2 3.2
Jewel 38 3.1 2.9 2.5 3.2 2.9
TIB* 2.9 3.3 3.2 3.3 3.3
CN 317 3 2.9 2.8 3.2 3.1
Kandee * 2.6 3.3 4.3 3.7 3.5
Nemanete* 2.9 3.4 3.1 3.7 3.3
Salyboro 2.4 2.2 1.9 2.6 2.3
Tainung 64 3.4 3 2.8 3.1 3.1
VSP 3 2.8 2.3 2 3.3 2.3
Resisto 3 3.4 2.8 3.3 3.1
W-151 * 3.6 3.7 3.4 3.5 3.6
Julian 3.4 2.8 2.5 3.3 3
Tainung 65* 3 3.4 3.3 3.8 3.5
Carrot-C (local)* 3.7 4.5 4.4 4.4 4.4
Mayai* 2.9 2.7 3.2 3.5 3.3
N= 26; Scores: 1= Very bad, 2= Bad, 3= Moderate, 4= Good, 5= Very good
*Selected varieties for further adaptability studies and on-farm evaluation and promotion

Proceedings of the 13th ISTRC Symposium, Arusha, Tanzania, 2007
744
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