Abstract Storage of sweetpotato roots for a prolonged period is a great challenge at the smallholder farmer level in Mozambique. Piecemeal harvesting allows a continuous supply of roots for household consumption for several months if weevil infestation is avoided. No systematic study has been done to look at the dynamic changes in yield and nutritional content among orange-fleshed sweetpotato (OFSP) cultivars harvested at different times in Mozambique. The objectives of the studies were to determine yield and changes in key macro- and micronutrients associated with early or late harvesting of OFSP cultivars in Mozambique. Four trials were established at Gurué in December 2015. The trials were classified into harvesting period, 3, 4, 5, and 6 months. Each trial had 30 OFSP cultivars laid in a randomised complete block design with three replications. Twenty-two of the cultivars are already released in Mozambique, 2 are elite clones, and 3 are common checks in 2016. Yield measurements were done in the field and samples were selected and sent to the quality laboratory in Maputo for determination of dry matter (%), β-carotene (mg/100g dry weight basis [dwb]), iron (mg/100g dwb), zinc (mg/100g dwb), and carbohydrate content, including starch, using near-infrared spectrometry. Data of the collected traits were analysed using R. The cultivars had significant differences in the measured traits within each harvesting period and among the harvesting dates. Yield and dry matter sharply rose as the harvesting period increased from the date of planting. Sweetpotato is perennial, hence partitioning of photosynthates to the storage roots is a continuous process. Dry matter, starch, iron, and β-carotene increased linearly in some cultivars as harvesting was prolonged; zinc was not affected by harvesting period. Genotype x environment interaction was small for the quality traits. Stability of micronutrients is essential for piecemeal harvesting. The study allowed accurate grouping of the cultivars tested into maturity groups as this was never done before Abilio Alvaro

1. The Sweetpotato Action for Security and
Health in Africa (SASHA) is a five-year
initiative designed to improve the food security
and livelihoods of poor families in Sub-
Saharan Africa by exploiting the untapped
potential of sweetpotato. It will develop the
essential capacities, products, and methods to
reposition sweetpotato in food economies of
Sub-Saharan African countries to alleviate
poverty and under-nutrition.
YIELD AND NUTRITION QUALITY
STABILITY OF ORANGE-FLESHED
SWEETPOTATO CULTIVARS ACROSS
DIFFERENT HARVESTING PERIODS,
MOÇAMBIQUE
By
A. Alvaro, M.I. Andrade, G.S.
Makunde, F. Dango, O. Idowou &
W. Gruneberg
African Potato Association
Conference, 10– 13 October 2016,
United Nations Conference
Center, Addis Ababa, Ethiopia

2. Introduction
• Orange-fleshed sweetpotato (OFSP) contains:
(1)Beta-carotene and other micronutrients as well as
energy giving compounds such carbohydrates
(2)Both leaves and roots are consumed
• OFSP is ensures food security crop in drought
prone areas
• Extraction of juice from the roots
• Roots can be processed into flour to make
different bakery products (buscuits, bread, cakes
etc)

3. Some farmer prefered traits in
Moçambique
Pre-harvest Post-harvest
High storage root yield Sweetness
Early maturity Marketability
Pest and disease resistance Good root shape
Tender leaves
Ability to grow all seasons
Good in-ground storability

4. The importance of early maturity in
smallholder agriculture
• Early maturity is the ability to give mature roots and
attain a high storage root yield between 3 to 4 months
after planting.
• This bridges the hunger gap before harvest of main
crops – e.g maize or cassava
• &
• allows piecemeal harvesting if in-ground storability is
good
• Early maturity is more preferable where sweetpotato is a
commercial crop & where there is an terminal dry spell

5. Objectives
The objectives of the studies were to:
•determine storage root yield AND changes in key
macro- and micronutrients associated with early or
late harvesting of released cultivars in
Moçambique

6. Methodology
• Four trials were established at Gurue in December
2015 (rainfed)
• The trials were classified into 4 harvesting periods;
90, 120, 150 and 180 days after planting (DAP).
• Each trial had 22 released cultivars and 3 checks
laid in a randomized complete block design with
three replications

7. Traits measured for all trials
In the field
Storage root yield, vine yield, weevil damage,
root size
Quality laboratory
Dry matter, beta-carotene, iron, zinc, starch
and sugars

8. Harvesting
At harvest time two middle rows of 39 plants were
used to measure the following traits:
•Storage root yield (t/ha) after digging up the roots
with hoes and weighing all from the net plot on a
balancing scale.
•Vine yield (t/ha) by manually cutting the above
ground plant parts on the net plot, bulking them
and weighing on a balancing scale.

9. Harvesting
• Weevil damage using a 1–9 scale, where 1 = no
damage, 3 = light damage, 5 = moderate
damage, 7 = severe damage and 9 =extremely
severe damage.
• Other injuries or damages to the roots were
recorded using the above scale.
• Root size using 1-9 scale, 9 = extremely big, 7 =
big, 5 = medium, 3 = small, 1 = very small.

10. Laboratory analysis
Three roots were randomly selected from each plot
and sent to laboratory to assess quality traits.
•Dry matter content (DM, %) by taking a sample of
50 g after bulking three roots and freeze drying for
72 hours. After freeze drying, samples were
reweighed for dry matter determination
•β-carotene, zinc, iron, starch and sugars were
read in NIRS according to Burgos et al. 2009 using
ground samples from freeze drier.

11. Data analysis

12. Cultivar performance across DAPs
Average performing genotypes at 90 DAP

13. Root quality across DAPs
Cultivar Root size ( 1- 9) Weevil damage (1- 9) Other root damage (1- 9)
120DAP 150DAP 180DAP 120DAP 150DAP 180DAP 120DAP 150DAP 180DAP
Amelia 9.1 3.7 5.0 7.0 5.7 6.3 4.0 3.7 4.3
Bela 4.3 3.0 5.7 4.3 6.3 7.0 3.7 4.3 5.7
Cecilia 4.3 4.3 5.0 3.7 5.7 7.7 3.0 4.3 5.0
Chingova 6.0 5.7 5.3 3.7 6.0 8.0 2.0 4.0 5.7
Delvia 6.9 5.7 6.3 1.1 5.7 7.7 1.3 5.7 7.0
Erica 5.0 5.0 5.0 2.3 5.7 7.0 2.3 4.3 4.3
Esther 6.1 4.3 5.0 4.0 5.0 5.0 3.8 4.3 3.0
Gloria 7.1 6.3 6.3 2.0 6.3 7.7 2.8 5.7 5.7
Ininda 5.7 5.0 6.3 2.3 5.0 7.7 2.3 5.0 6.3
Irene 5.7 3.0 4.3 3.0 5.7 5.7 3.0 3.7 4.3
Jane 7.7 4.3 6.3 4.3 6.3 8.3 4.3 4.3 7.0
Jonathan 6.7 5.3 5.7 3.3 6.3 8.3 2.0 4.0 6.3
Lourdes 5.7 5.0 5.0 3.7 5.7 7.7 3.0 4.3 6.3
Victoria 5.7 5.0 5.0 1.7 6.3 7.7 1.0 4.3 6.3
Melinda 3.0 5.0 4.3 3.7 6.3 5.0 2.3 5.0 4.3
MUSG11016-1 3.7 5.7 5.0 1.0 5.0 8.3 1.0 4.3 7.0
Bita 7.9 5.7 5.7 1.0 5.7 9.0 1.1 5.0 7.0
Lawrance 4.3 4.3 5.0 3.0 5.7 8.3 1.7 3.7 6.3
Caelan 8.9 6.3 5.0 3.1 5.0 8.3 1.3 4.3 7.0
Ivone 6.3 7.2 5.7 1.0 5.0 8.3 1.0 5.3 5.7
Bie 4.3 5.7 6.3 2.3 5.7 9.0 1.0 3.7 7.7
MUSGP0646-126 3.0 5.0 3.7 1.0 6.3 5.0 1.0 5.0 4.3
Namanga 3.7 5.0 4.3 3.7 5.7 6.3 3.0 3.7 5.0
Resisto 7.3 5.7 6.7 2.0 4.7 8.3 1.3 6.3 6.7
Sumaia 3.0 3.7 5.0 3.0 5.7 7.7 2.3 4.3 6.3
Tio Joe 3.7 3.7 4.3 3.0 5.0 7.7 2.3 3.7 4.3
Alisha 6.3 7.8 5.7 1.7 6.3 8.3 1.7 3.8 7.7
Mean 5.6 5.0 5.3 2.8 5.7 7.5 2.2 4.4 5.8

14. Nutritional changes – BC, Fe & Zn
Variety Beta carotene (mg/100gDW) Iron (mg/100gDW) Zinc (mg/100gDW)
120DAP 150DAP 180DAP 120DAP 150DAP 180DAP 120DAP 150DAP 180DAP
Bela 29.8 26.5 26.0 1.9 1.7 1.8 1.2 1.1 1.2
Cecilia 17.3 12.6 20.4 1.7 1.7 1.9 1.3 1.2 1.3
Chingova 0.0 0.0 0.0 1.6 1.5 1.6 1.2 1.3 1.3
Erica 29.2 23.4 23.4 1.9 1.9 2.0 1.3 1.2 1.3
Esther 22.1 19.8 23.0 2.0 1.7 2.0 1.4 1.3 1.5
Gloria 17.3 28.7 21.4 1.7 2.0 2.0 1.2 1.3 1.3
Ininda 27.4 21.3 18.1 2.0 1.8 1.9 1.5 1.2 1.3
Irene 16.0 12.4 16.7 1.7 1.8 1.7 1.3 1.2 1.1
Jane 19.5 20.2 22.7 1.6 1.8 1.9 1.1 1.3 1.3
Jonathan 0.0 0.0 0.0 1.4 1.5 1.7 1.0 1.0 1.1
Lourdes 15.6 10.9 17.3 1.5 1.7 1.5 1.2 1.2 1.1
Victoria 31.1 38.7 42.0 2.1 2.1 2.3 1.5 1.5 1.6
Melinda 15.2 13.9 17.8 1.8 1.8 1.7 1.3 1.2 1.2
MUSG11016-1 0.0 0.0 0.0 1.6 1.6 2.0 1.2 1.2 1.3
Bita 0.0 0.0 0.0 1.5 1.6 1.7 1.0 1.1 1.2
Lawrence 11.6 9.3 11.9 1.8 1.7 1.8 1.4 1.3 1.4
Ivone 14.0 22.5 30.6 1.7 2.2 2.0 1.1 1.5 1.2
Bie 0.0 30.0 7.1 1.5 1.6 2.1 0.9 1.1 1.4
MUSGP0646-126 0.0 4.8 5.2 1.6 1.7 2.1 1.2 1.3 1.5
Namanga 27.8 27.5 30.1 1.8 1.9 2.0 1.2 1.2 1.3
Resisto 21.6 22.4 27.0 1.8 1.9 2.0 1.1 1.3 1.4
Sumaia 27.3 23.6 27.9 1.9 2.2 2.0 1.3 1.3 1.2
Tio Joe 38.2 35.5 37.5 2.2 2.1 2.1 1.4 1.3 1.3
Alisha 14.1 14.6 21.6 1.6 1.9 2.0 1.2 1.3 1.5
Mean 1.7 1.8 1.9 1.2 1.2 1.3

15. Nutritional changes- DM, Starch, Glucose
& Sucrose
Variety Dry matter % Starch % Glucose % Sucrose %
120DAP 150DAP 180DAP 120DAP 150DAP 180DAP 120DAP 150DAP 180DAP 120DAP 150DAP 180DAP
Bela 25.2 24.7 22.2 54.8 53.1 44.7 6.5 6.2 8.5 13.2 16.6 19.5
Cecilia 29.8 29.1 22.6 64.6 62.4 52.0 4.8 4.6 7.7 6.3 8.7 13.0
Chingova 32.9 37.2 35.4 63.6 69.9 67.3 4.1 2.8 3.2 8.4 3.1 5.8
Erica 27.4 24.9 23.5 60.2 57.8 54.4 5.7 6.9 9.1 7.7 7.7 7.8
Esther 27.9 26.8 27.7 59.4 59.0 59.7 5.9 4.5 4.9 9.1 11.2 9.0
Gloria 33.2 36.3 37.0 62.8 65.0 64.3 4.1 3.4 3.2 8.8 6.8 6.6
Ininda 30.0 27.9 29.9 61.4 59.1 62.6 4.5 4.5 3.8 9.2 11.8 8.7
Irene 31.1 29.3 28.3 62.4 58.7 55.1 4.2 3.8 6.1 8.8 12.2 13.9
Jane 25.6 31.9 31.3 57.9 61.8 59.7 7.1 3.7 4.5 9.7 8.3 9.5
Jonathan 24.9 27.8 23.4 55.9 59.4 50.8 8.3 5.3 7.9 9.8 12.2 16.5
Lourdes 33.1 34.7 32.4 67.1 65.8 63.2 3.8 3.5 4.3 4.9 5.6 7.5
Victoria 29.0 27.3 20.9 55.6 56.2 48.5 5.6 4.3 6.2 10.0 12.6 15.4
Melinda 23.4 25.6 23.6 54.0 55.1 53.0 6.9 5.7 5.8 13.3 15.2 16.6
MUSG11016-1 28.7 31.3 27.2 59.1 66.7 61.7 5.7 4.3 4.3 8.5 3.1 8.2
Bita 31.7 38.3 36.5 60.1 68.6 67.9 5.5 3.6 3.5 9.4 3.4 4.5
Lawrence 36.2 33.5 34.9 66.8 66.7 66.9 3.4 3.2 3.0 2.2 4.4 4.5
Ivone 26.7 27.9 21.8 57.1 55.1 48.6 9.2 7.5 8.1 5.9 9.6 16.1
Bie 22.9 26.5 27.7 49.8 54.9 56.4 13.7 8.4 6.1 5.4 9.2 9.2
MUSGP0646-126 29.6 32.9 30.7 65.1 67.9 64.8 3.9 3.2 3.1 6.8 4.1 5.0
Namanga 29.4 26.4 23.2 61.5 52.2 46.2 4.8 5.2 7.2 9.4 18.2 18.9
Resisto 28.5 31.9 31.1 60.1 63.3 60.6 8.1 4.9 5.2 3.9 5.1 6.7
Sumaia 24.8 21.2 21.6 58.2 49.4 49.6 6.6 9.1 9.8 8.3 11.9 10.9
Tio Joe 24.4 26.3 24.3 55.5 53.4 47.8 5.6 5.6 7.1 11.1 14.3 18.7
Alisha 31.4 29.3 30.1 58.4 59.4 61.1 5.8 5.1 4.3 9.3 9.6 9.0
Mean 28.7 29.5 27.8 59.6 60.0 56.9 6.0 5.0 5.7 8.3 9.4 10.9

16. Summary
Harvesting can commence as early as 90DAP for
varieties such as:
•Irene, Bela,Tio Joe, Sumaia & Cecilia (all
released in 2011)
&
•Lawrence & Ivone (released in 2016)

17. Summary contd’’
• Stability analysis showed harvesting at 150DAP
was stable and had higher storage roots yield
than 90DAP and 120DAP.

18. Summary contd’’
Farmers pay particular attention to taste and
quality traits before adopting a variety
•Population means for starch were 59.6
(120DAP), 60.0 (150DAP) and 56.9 % (180DAP)
•Sucrose was the major sugar in all the varieties at
all stages of development
•There was a quantitative increase in DM% during
development, though cultivar depended.

19. Summary contd’’
The DM and starch % levels of some of the
released OFSP varieties are high
•The breeding program in Mozambique had
worked to improve DM in orange fleshed clones
since 2009.
•The new ‘hard’ status in the released varieties in
Mozambique enhance consumer acceptance and
help combat vitamin A deficiencies.

20. Summary contd’’
• Early maturing cultivars fit well in short growing
seasons, especially now with the threats of
climate change.
• High storage root yields at 3 months assist to
break the hunger period and income generation
where sweetpotato is a commercial crop
• Weevil damage and other root injuries are often
associated with drought and significantly
increased as harvesting was delayed.

21. Conclusion
• Piecemeal harvesting can begin as early as 3
months after planting in early maturing cultivars;
Irene, Bela, Tio Joe, Sumaia, Cecilia, Lawrence
and Ivone

22. Acknowlegements
• The authors thank the Bill and Melinda Gates
Foundation for providing financial support
through the SASHA project in Mozambique.
• We also acknowledge nine students who
assisted with trial management and data
collection.