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VARIETAL PERFORMANCE OF SWEET POTATO
DURING WET AND DRY PLANTING SEASONS
IN LA UNION PROVINCE, PHILIPPINES
Renato F. Limon and Lilia O. Sampaga
Don Mariano Marcos Memorial State University
North La Union Campus
Bacnotan, La Union
ABSTRACT
Eight promising varieties of sweet potato recommended by Northern Philippines Root
Crops Training Center (NPRCTC), La Trinidad Benguet were evaluated during the wet and dry
season planting to determine location specific varieties suited for each season. The specific
objective of the study was to to evaluate the agronomic characteristics and to determine the
most adaptable varieties with high yield potential and resistant to pests.
Results revealed that sweet potato varieties Bengueta, Inubi, Tocano and PSBSp22 are
recommended for both wet and dry season planting. Super Beaurelli variety is highly
recommended for wet season planting. Varieties NSIC 30 and Japanese Ubi are recommended
for dry season planting for higher yield and resistant to weevil infestation respectively.
Keywords: Infestation, Sweet Potato, Varieties, Weevil, Yield
INTRODUCTION
Sweetpotato is a popular and commonly grown root crop in the province of la Union. It
is one of the staple foods of Filipinos in some areas of the country like Ilocos Region. It is
popularly known as “Kamote Lanut”. The tuberous roots are a good source of starch and flour,
and as ingredient in non-alcoholic beverages, catsup, jellies, jam, soy sauce, bakery and nonbakery products. Furthermore, sweet potato is rich in antioxidant and nutrients useful in
maintaining a healthy body. Sweet potato is also used as food vegetable both using its
tuberous roots and leafy tops. The viny stems are also used as animal feed either cooked or
raw.
Sweetpotato requires a little input in terms of labor and production cost. One limiting
factor in sweetpotato production is the lack of information on desirable and adaptable varieties
which are location specific with high yield potential and resistant to weevil infestations to
increase farm income.
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METHODOLOGY
Two planting trials were conducted and evaluated during the wet and dry season of
planting. Results of the soil analysis revealed that the soil is light with a soil pH of 6.1 with 20g
Urea (N) per hill as nutrient recommendation.
Terminal sweet potato cuttings as planting materials were selected by cutting 30-35 cm long,
vigorous and free from pests. The cuttings were wrapped with dried banana leaves, moistened
and were placed under shady areas for 8 hours.
Land Preparation
The experimental area was cleared from shrubs, tall and viny weeds prior to land
preparation. It was rotavated and the final harrowing was done a day before planting to obtain
fairly fine tilt to ensure soil aeration and optimum weed control. Prior to planting, continuous
furrows were set at 1 m apart at a depth of 20cm using an animal drawn plow.
Treatments and Statistical Design
The varietal treatments were randomly assigned following the Randomized Complete
Block Design (RCBD). There were eight varieties used which were replicated 3 times. The
treatments were the following: V1- Tocano, V2 – Bengueta, V3 - PSBSp 22 (improved check), V4 SP Native (local check), V5 - Super Beaurelli, V6 - NSIC 30, V7- Inubi, and V8 - Japanese Ubi.
Duncan’s Multiple Range Test (DMRT) was used in the comparison of treatment means.
Planting
The sweetpotato cuttings of the different varieties were planted at a distance of 30 cm
between hills and were slipped in the furrows at slanting position burying at least three nodes.
There were 10 cuttings planted per row or 40 cuttings per plot. Basal application of urea
fertilizer at a rate of 20g per hill was done followed by immediate irrigation. Hilling-up was
done one month after planting to control the weeds and enhance better root development.
Cultural Management
Basal application of urea fertilizer at a rate of 20g per hill was done. Hilling-up was done
one month after planting to control weeds and provide better root development.
Supplemental watering was done once a month during the dry season planting. Spot weeding
was also done twice in the wet season planting.
RESULTS AND DISCUSSIONS
Agronomic Characteristics
Most of the varieties have elongated tubers except the Tocano and the check variety
which are round and round to oblong. With regards to root skin color, Tocano and Bengueta
have the same root skin color of light pink. SP Native has light orange. The check variety (V3)
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has purple, Super Beaurelli has red root skin color and Japanese Ubi has white root skin color,
NSIC 30 is peach and Inubi variety has red violet root skin color.
Table 1. Agronomic characteristics of the sweetpotato varieties at wet and dry season
planting.
As to root flesh color, most of the varieties had light yellow except for the Japanese Ubi
which has white, Inubi had also white with violet tinge and NSIC 30 has a yellow orange flesh
color.
Number and length of the longest Vines Per Plant During Wet and Dry Season
The vine production of the eight sweetpotato varieties at wet and dry season planting is
shown in Table2.
During wet season planting, all the varieties are of comparable number of vines which
indicates that the new varieties are adoptable to the locality. However, during the dry season
planting, Inubi had significant more number of vines as compared to the check varieties but was
found comparable to new varieties such as Super Beaurelli, Bengueta, NSIC 30, and Tocano.
Moreover, the PSB Sp22 check variety had comparable number of vines per plant to the new
varieties Super Beaurelli, Bengueta, NSIC 30, and Tocano. However, all new varieties are
adoptable in the locality when compared to the Sweet Potato Native check variety (V4).
As to the length of vine of the different sweetpotato varieties at both wet and dry
season planting, results shows that on wet season planting both check varieties have significant
longer vines (more than 3.5 meters long) compared to new varieties tested in the locality. The
new varieties ranged from less than 1.0 meter up to 2.72 meters. However, at dry season
planting, both check varieties have comparable vine length with new varieties such as Tocano,
Inubi and Japanese Ubi.
Table 2. Number and length of the longest Vines Per Plant During Wet and Dry
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Weight (kg) of Above-ground Biomass During Wet and Dry Season of Planting
The weight of biomass at wet and dry season of the eight sweetpotato varieties is
shown in Table 3. At wet season planting, new varieties Tocano, Bengueta and Super Beaurelli
have comparable biomass with the check varieties. However, at dry season planting, all new
varieties have comparable biomass with the two check varieties indicating their adoptability in
the locality.
Table 3. Weight (kg) of above-ground biomass.
Number of Days to Maturity
The crop maturity of the eight sweetpotato varieties during wet and dry season of
planting is presented in Table 4. Result revealed that the new varieties tested were early
maturity ranging from 80-95 days during wet season planting which is similar to the two check
varieties. However at dry season planting, shorter duration of crop maturity was noted ranging
duration of crop maturity was noted ranging from 83-95 days. This finding indicates that the
new varieties tested are adoptable in the locality.
Table 4. Number of days to maturity during wet and dry season planting.
Number and weight (kg) of sweetpotato tuber roots during wet and dry season planting
Table 5 shows the number and weight of tuber roots harvested on the different
sweetpotato varieties. At wet planting, result showed that the improved check variety PSBSP22
produced the most number (8.07) of tuber roots per plant which was found comparable to
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Super Beaurelli and Bengueta. The least tuber root production was obtained from Tocano (3.53)
but was found comparable to Japanese Ubi, NSIC 30, SP Native and Inubi. However at dry
season planting, NSIC 30 produced the most number of tuber roots per plant but was found
comparable to Bengueta, Inubi, Tocano, and the improved check variety (PSB Sp 22).
As to the overall effect of planting season, it reveals that new varieties Bengueta, Super
Beaurelli, and Japanese Ubi are intended for both wet and dry season of planting. Tocano and
NSIC 30 have high yield reduction (56.25% and 39.65%) at wet season planting.
Table 5. Number of and weight of sweetpotato tuber roots during wet and dry season
planting.
At wet season planting, result revealed that Bengueta produced the heaviest weight of
1.06 kg/plant which was found comparable to the improved check variety (V3) and Inubi. Other
new varieties such as Tocano, Super Beaurelli and Japanese Ubi were also found comparable to
the improved check variety. The SP native variety produced the least (0.45kg/plant) which was
found comparable to NSIC 30 variety (0.46kg/plant).
Tuber Root Yield (Tons/ha) During Wet and Dry Season Planting
Table 6presents the tuber root yield of the eight sweetpotato varieties in tons per
hectare. At wet season of planting, Bengueta produced the highest yield (35.43 t/ha) which was
found comparable to the improved check variety (22.99 t/ha) and Inubi (32.34 t/ha). Other new
varieties (Tocano, Super Beaurelli and Japanese Ubi were also found comparable to the
improved check variety.
At dry season planting, Bengueta have the heaviest yield (33 t/ha) but was found
comparable to Tocano, NSIC 30, Inubi and the improved check variety (V3). Moreover, Super
Beaurelli, Japanese Ubi and SP native were also found comparable to the improved check
variety.
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Table 6. Weight of tuber root per plant during wet and dry season of planting per plant and in
tons per hectare
Percent (%) Marketable Tubers During Wet and Dry Season of Planting
The percentage of marketable tuber root of the eight sweetpotato varieties during wet
and dry season of planting is shown in Table 7. Result revealed that Bengueta, Tocano and NSIC
30 exhibited 100% marketability without infestation and the presence of small size tubers
during wet season. New varieties generally have high percentage of marketable tuber roots
during wet and dry season. However, the native check variety (V4) showed the least percentage
of marketable tubers due to high sweetpotato weevil infestation.
Table 7. Percent (%) marketable tuber roots of sweetpotato per plant during wet and dry
season of planting.
Degree of Infestation
Table 8 presents the weevil rating and degree of infestation of the different
sweetpotato varieties. It can be noted that the SP Native variety was rated highly susceptible
with a weevil rating of 20.28% on both wet and dry season of planting. The resistant varieties
were Tocano, Bengueta, NSIC 30, Super Beaurelli, and the improved check variety. The Inubi
and Japanese Ubi were rated with moderately resistant. However, at dry season of planting, the
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new varieties were rated resistant to moderately resistant. The native check variety (V4) was
rated highly susceptible.
Table 8. Degree of sweetpotato weevil infestation during wet and dry season of planting.
Legend: 0 – 5% - Resistant, 6-10% -Moderately Resistant, 11-15% - Slightly Resistant, 16-20%Susceptible, 21% and Above - Highly Susceptible
Organoleptic Characteristics of Sweetpotato
Table 9 presents the results of the organoleptic test on the different sweetpotato tuber
roots according to the appearance, texture, palatability and general acceptability during wet
and dry seasons under DMMMSU conditions.
In terms of appearance varieties Tocano, Bengueta, Inubi, Japanese Ubi and the improve
check variety (PSBSp17) were rated “like very much”. Super Beaurelli and NSIC 30 were rated
as “like extremely” with numerical rating of 81-83% during wet season planting. During dry
season planting, NSIC 30, Inubi and Japanese Ubi were rated as “like extremely”. All other
varieties were rated as “like very much” except variety sweet potato native (SP Native) which is
rated as “like moderately’.
As to texture the sweet potato varieties tested was rated like very much and like
extremely.
As to the palatability of sweet potato tubers, it can be noted that most of the varieties
were rated as “like very much” and NSIC 30 was rated as “like extremely” either planted both
wet and dry season of planting. As to general acceptability, the same rating (wet and dry
season planting) was noted. Varieties Tocano, Bengueta and Super Beaurelli have the same
rating with the improve check variety “like very much”. NSIC 30, Inubi and Japanese Ubi were
rated as “like extremely” and the native check was rated as “like moderately”.
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Table 9. Organoleptic characteristics of sweetpotato tuber roots tested one week after
harvest, DMMMSU, DS, 2013
Legend:
81-90 - Like Extremely (LE)
71-80 – Like very Much (LV)
61-70 – Like Moderately (LM)
51-60 – Like Slightly (LS)
41-50- Neither Like nor Dislike (NLD)
31-40- Dislike (D)
21-30- Dislike Moderately (DM)
11-20 – Dislike Very Much (DVM)
1-10 – Dislike Extremely (DE)
Correlation Analysis on the Growth and Yield Parameters
Results of the correlation analysis on the weight of tuber roots, weight of above-ground
biomass and number of vines per plant is shown on Table 10.
Result connotes a positive correlation on the weight of biomass, and number of vines,
and weight of tuber roots. This implies that the more number of vines the plants have the
heavier the above-ground biomass and the more number of tuber roots.
Table 10. Correlation analysis on the growth and yield parameters obtained on sweet potato
varieties, DMMSU, WS 2011.
Correlations
Wt. of biom ass
No. of vines
Wt. of roots
Pearson Correlation
Sig. (2-tailed)
N
Pearson Correlation
Sig. (2-tailed)
N
Pearson Correlation
Sig. (2-tailed)
N
Wt. of
biomas s
1.000
.
8
.806*
.016
8
.545
.163
8
No. of vines
.806*
.016
8
1.000
.
8
.781*
.022
8
Wt. of roots
.545
.163
8
.781*
.022
8
1.000
.
8
*. Correlation is si gnifi cant at the 0.05 level (2-tail ed).
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Climatological Data
The mean maximum and minimum temperature, rainfall and relative humidity during
the growth and development stages of the different sweet potato varieties is shown in Table
11.
The highest maximum temperature of 32.8oC was recorded in March 2013 and the
lowest was recorded in January (30.2oC). Minimum temperature ranged from 20.3oC to 23.4oC.
The average relative humidity during wet season was 91.98% and was highest in September
2011 and lowest in the month of July 2011. Average relative humidity during dry season
planting was 80.36%. The highest RH was in the month of December 2012 and was lowest in
the month of August 2011 (87.0%) and lowest in March (83.0%). The average rainfall during
wet season was 47.25mm, the highest was recorded in August 2011 and lowest in October
2011(.2mm). During dry season planting, the average rainfall was 0.084 mm. the highest was
recorded in November 2012 and lowest in February 2013 (0.1mm) and no rain occurred in
December 2012. This implies that the climatological data under DMMMSU conditions is
suitable for growing sweet potatoes during wet and dry seasons of planting.
Table 11. Mean maximum and minimum temperature, rainfall and relative humidity during
the growth and development of the sweet potato varieties, DMMMSU, DS, 2013
Net Income
An estimated net income ranging from P133,000.00 to P425,450.00 per hectare
basis was obtained during wet season planting and P99,200.00 to P422,750.00 durinf dry
season planting.
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Table 12. Estimated Net Income of 1 ha Sweet Potato.
Table 13. Cost of Production of 1 ha Sweet potato.
CONCLUSIONS AND RECOMMENDATIONS
Conclusions:
1. Tocano and Bengueta produced the most number of secondary vines and was
significantly comparable to Inubi and the improve check variety (PSBSp22) during wet
season planting. During dry season planting Inubi outnumbered the other varieties.
Sweet Potato Native produced the least and was comparable to Japanese Ubi, PSBSp 22
and Tocano.
2. The two check varieties (SP Native and PSBSp22) produced the longest vine during wet
season planting and Japanese Ubi produced the least. During dry season planting,
Sweet potato native produced the longest vine and was comparable to Japanese Ubi,
Inubi and the improve check variety (PSBSp22). Super Beaurelli and Bengueta produced
the shortest vine.
3. Japanese Ubi produced the heaviest above-ground biomass during dry season planting
but produces the lightest during wet season planting.
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4. All varieties are early maturing (80-95days).
5. The improve check variety PSBSp22 outnumbered all other varieties in terms of number
of tuber roots and was found comparable to Bengueta and Super Beaurelli during wet
season planting. Tocano produced the least number of tuber roots. NSIC 30 and
Bengueta produced the most number of tuber roots and were significantly comparable
to Inubi, Tocano and the check variety PSBSP22. SP Native produced the least number
of tuber roots during dry season planting.
6. During wet season planting, Bengueta and Inubi significantly produced the highest tuber
root yield and was comparable to the improve check variety (PSBSp22). NSIC 30 and
Sweet potato native produced the least tuber yield. During dry season planting,
Bengueta significantly outyielded the other varieties and was found comparable to
Tocano, NSIC 30, Inubi and the check variety (PSBSp 22).
7. Bengueta, Tocano and NSIC 30 produced the highest percentage of marketable tuber
roots per plant during wet season planting and Japanese Ubi produced the highest
marketable tuber root yield during dry season planting.
8. All the varieties were resistant to weevil infestation except SP Native variety which is
susceptible both wet and dry season planting.
Recommendations:
1. The sweetpotato varieties Bengueta, Inubi, Tocano and PSBSP22 are recommended for
both wet and dry season planting.
2. The variety Super Beaurelli is highly recommended for wet season planting only.
3. Other varieties NSIC 30 and Japanese Ubi are highly recommended for dry season
planting for higher yield, and resistant to weevil infestation.
REFRENCES
AMALIN, D.M., E. CHUSOY AND M.T.L. GERPACIO. Selection for resistance to the sweet potato
weevil, Cycles formicarius Fabr. The Potato and Sweetpotato in Southeast Asia and the Pacific
region. CIP, Manila, Phil. Pp. 127-132.
La Union Technoguide. 1991. La Union Technoguide on Sweetpotato Production.
TECHNOPACK, Don Mariano Marcos Memorial State University, Bacnotan, La Union.
NERI, F.R. 1990. Performance of Promising Sweet Potato Cultivars/Lines in La Union. Terminal
Report. DMMMSU, Research Office, Bacnotan, La Union.
MACFARLANE, R. and G.V. JACKSON. 1989. A leaflet on the sweet potato weevil. South
pacific Commission. New Zealand. 355.
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