Tuesday theme 2 1050 1105 room 11 njoku

1. EVALUATION OF IN-GROUND CURING
AND STORAGE METHODS OF
SWEETPOTATO FRESH ROOTS
PRESERVATION IN RAINFOREST ZONES
OF NIGERIA
Researchers: Njoku, J.C., Ehisianya, C.N., Amajor, J.U.

2. Introduction
• Nigeria is the 3rd highest producer of sweetpotato
globally coming after China and Uganda
• Though regarded as second crop in Nigeria, it is
assuming increasing importance as domestic
consumption increases significantly
• Production level has increased over the years (0.14
Mt in 1990-2.7 MT in 2012)
• Yield estimate ranged from 3.1-6.0 MT/ha in
Farmers field
• Storability of roots a major constraint
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3. • When stored under room temperature, roots may
lose 10-15% moisture under two weeks.
• Farmers in most cases engage in piece-meal
harvesting to avoid high storage losses and glut
• Loses occur in-ground due to weevil attack and
subsequently rots
• Weevil cause losses ranging from 60% to almost
100% during dry season
• Hence the need to fashion out appropriate in-
ground storage methods that will be amenable to
small holders setting
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4. Objectives
• To evaluate the effect of sweetpotato defoliation
on yield of fresh roots over time
• To evaluate the effect of defoliation and earthen-
up on in-ground storability and quality of fresh
roots

5. Materials and methods
• Trial laid out as split plot design in RCBD replicated
3 times
• Main treatment=7 varieties (Butter milk,
UMUSPO3, Ex-Igbariam, Kwara, UMUSPO1,
TIS8164 %& TIS87/0087
• Sub-treatments= 1.Defoliated 1WBH
2. Defoliated at Harvest
3. Defoliated, hilled up and
harvested one month after
4. Defoliated, hilled up and
harvested 2 months after

6. Materials and Methods Continu….
• Data Collection
Stand count at 2wap, 4wap & at Harvest
 Number of roots affected by rot
Number of root affected by weevil
Number of Marketable roots (>100gms)
Number of unmarketable roots (<100gms)
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7. Results

8. Table1. Mean number of stand/m2 at Harvest
Variety In-ground curing methods
Cured Uncured Harvest
1MAS
Harvest
2MAS
Mean
Butter Milk 1.8 1.6 1.9 1.8 1.8
UMUSPO3 2.9 2.7 2.7 2.8 2.8
Ex-Igbariam 2.6 2.1 2.6 2.3 2.4
Kwara 2.9 3.0 2.6 2,6 2.8
UMUSPO1 2.4 2.0 2.3 2.8 2.4
TIS8164 2.2 1.6 1.7 1.7 1.8
TIS87/0087 2.7 2.7 2.8 2.5 2.7
Mean 2.5 2.3 2.4 2.4
LSD (0.05):Variety=.46*, Curing method=0.22ns. Var. x curing method=

9. Table1. Mean storage roots yield (t/ha) at Umudike location
in 2013 cropping season
Variety In-ground curing methods
Cured Uncured Harvest
1MAS
Harvest
2MAS
Mean
Butter Milk 8.0 10.2 8.1 6.1 8.1
UMUSPO3 17.0 19.0 16.0 14.7 16.7
Ex-Igbariam 5.2 7.7 5.9 4.0 5.7
Kwara 7.7 7.2 6.4 5.3 6.7
UMUSPO1 18.6 14.4 14.2 8.2 13.8
TIS8164 5.3 4.52 4.1 0.7 3.6
TIS87/0087 9.6 9.1 8.0 9.8 9.1
Mean 10.2 10.3 8.96 7.0
LSD (0.05): Variety=2.77**, Curing method=1,71**. Var. x curing

10. Table2. Mean storage roots yield (t/ha) at Umudike location
in 2014 cropping season
Variety In-ground curing methods
Cured Uncured Harvest
1MAS
Harvest
2MAS
Mean
Butter Milk 6.9 5.4 7.3 6.1 6.4
UMUSPO3 20.7 19.7 15.3 14.5 17.6
Ex-Igbariam 3.3 4.8 7.1 5.2 5.1
Kwara 2.2 1.7 4.8 2.3 2.7
UMUSPO1 12.4 10.9 17.0 10.5 12.7
TIS8164 3.5 3.7 4.3 4.4 4.0
TIS87/0087 8.7 8.6 10.2 7.0 8.6
Mean 8.3 7.8 9.4 8.3
LSD (0.05): Variety= 2.15* Curing method= 1.72ns, Var. x curing method=

11. Table3. Mean percentage (%) root rot Umudike location
Variety In-ground curing methods
Cured Uncured Harvest
1MAS
Harvest
2MAS
Mean
Butter Milk 0.7 0.7 19.0 33.1 13.4
UMUSPO# 1.0 0.0 8.3 4.7 3.5
Ex-Igbariam 0.0 0.0 0.8 7.7 2.1
Kwara 0.0 0.0 0.6 5.8 1.6
UMUSPO1 0.0 0.0 6.0 25.3 7.8
TIS8164 1.2 0.0 7.6 6.8 3.9
TIS87/0087 0.8 0.0 0.0 2.6 0.8
Mean 0.5 0.1 6.0 12.3
LSD (0.05): Variety= 8.02*, Storage methods= 6.06* VxS=16.04NS

12. Table4. Mean percentage (%) weevil infestation Umudike
location
Variety In-ground curing methods
Cured Uncured Harvest
1MAS
Harvest
2MAS
Mean
Butter Milk 3.0 3.4 0.0 5.3 2.9
UMUSPO3 2.6 2.6 4.3 8.6 4.5
Ex-Igbariam 1.1 0.0 0.8 7.7 2.4
Kwara 0.0 1.2 3.3 5.8 2.6
UMUSPO1 2.8 0.4 4.1 16.8 6.0
TIS8164 1.0 0.0 0.0 2.0 0.7
TIS87/0087 2.0 0.0 0.8 3.3 1.5
Mean 1.8 1.0 1.9 7.1
LSD (0.05): Variety= 4.04*,storage methods=3.06,* Var x storage=10.61ns

13. Results and Discussion
• Varieties tested differed in most cases on yield potentials,
pest and disease susceptibility.
• UMUSPO3 and 1(OFSP) produced more average yields in
both season compared to other varieties.
• More roots developed rots (12.3%)and weevils (7.1%)
when harvesting was delayed for 2 months compared to
cured, uncured and harvested after 1 month .
• Also UMUSPO1 and 3 were more susceptible to weevil
compared to Tis 8164, and TIS87/0087.
• This may have been due to varietal characteristics where
the former and the later were noted to be shallow and
deep rooted respectively 13

14. 14
UMUSPO3Fig1. Weevil infestation on shallow rooted UMUSPO3 OFSP
Variety

15. Conclusion & Recommendation
• Sweetpotato weevil (Cylas puncticollis) has been a major
problem to farmers and its actions predisposes roots to
rots thereby causing yield loss and low market value.
• This investigation revealed that sweetpotato roots can be
left in the soil for 1 month or more with minimal damage.
• For in-ground storage methods, sweetpotato plant should
be defoliated and ridges or mounds hilled up to close the
cracks that could create access for weevils to get to the
roots.
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16. Conclusion and recommendation Contin….
• Storing the roots in-ground following the procedures
discussed will prolong storage of roots more than 1
month after maturity to enable the farmers harvest
storage roots when needed.
• Sweetpotato breeders may evaluate for deep rooted
genotypes that may root beyond soil medium that
weevils may have access to.
•
• However, more research is suggested to investigate the
nutritional quality of the prolonged stored roots.
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