Monday theme 1 large briefing room m.laurie 1600 1615

1. Performance of ARC informal market
sweet potato cultivars in on-farm
trials
APA, Addis Ababa, 11/10/2016
Sunette Laurie, M Mtileni, W Mphela, S Tjale
ARC-Vegetable and Ornamental Plants (ARC-VOP),
Pretoria, South Africa

2. Introduction
• Sweet potato is an important indigenized root
crop in SA
• Features prominently in smallholder cropping
systems
 because of its versatility, ease to grow,
hardiness
 Orange cultivars presents a rich source of
provitamin A
• Vitamin A deficiency (VAD) in South Africa
– 43.6% of 1-9 years old (2012) – national
public health problem
– 27% of women at childbearing age (2005)

3. • Food security in SA (SANHANES, 2012):
 45.6% of population food secure (score of 0),
 28.3% were at risk of hunger (score 1–4) &
 26.0% experienced hunger (food insecure)
• Promoted by the ARC for food security, nutrition, income
generation and enterprise development
• Informal market estimated at 25000 – 30 000 t
• Large potential for processing into various products
Introduction (cont.)

4. 199062.1Ndou Monate Mvuvhelo
Bophelo
Impilo
Introduction (cont.)
• Breeding has focused on high yield, good root
quality, adaptability, high dry mass and sweet
taste (also β-carotene content)
• Cultivars released: Ndou & Monate (2003),
Impilo (2007), Bophelo (2011), Mvuvhelo (2013),
199062.1 (CIP: 2010)
• Trials across 5 research stations indicated:
o 29.5 – 36.2 t/ha (33.5) for total yield
o 17.3 – 24.6 t/ha (20.0) for marketable yield

5. Objectives
• Study objective: to test the performance of ARC
informal market cultivars in on-farm trials
• Present progress with vine distribution of new
cultivars

6. Materials and methods
• On-farm trials were conducted in 15 localities: 9 in
KwaZulu-Natal, 4 in Gauteng, 1 each in Eastern
Cape and Mpumalanga provinces across 2011/12
– to 2014/15.
• RCBD: 3 replicates; 6-7 cultivars (+Blesbok)
• 30/40 plants per plot
• Preplant 500 kg/ha 2:3:4
• Supplementary irrigation
• 5 months
Blesbok

7. *
*
*
*
Loc
Code
Location
name
Location details Region
PON Pongola Pongola Khiphunyawa
2013-14
Subtropical
*
*
* *
*
*
****
**
NEB Nebo Nebo Mamphokgo 2014-15 Cool
subtropical
DUM Paulpieters-
burg
Dumbe Paulpietersburg
2014-15
Cool
subtropical
BUL Nongoma 1 Bululwane - Nongoma
2012-13
Cool
subtropical
MLA Ulundi 1 Mhlabatsini - Ulundi 2012-13 Cool
subtropical
MAYE Nongoma 2 Maye - Nongoma 2014-15 Cool
subtropical
CEZ Ulundi 2 Ceza 1 Ulundi 2014-15 Cool
subtropical
KUT Soshanguve Kutlwano - Soshanguve
2011-12
Temperate
SIM Ekangala 2 Simajado - Bronkhorstspruit
2011-12
Temperate
WIN Winterveldt Winterveldt 2011-12 Temperate
SYA Ekangala 1 Siyathuthuka -
Bronkhorstspruit 2011-12
Temperate
MON Vryheid 1 Vryheid Mondlo 2013-14 Temperate
MVU Vryheid 2 Vryheid Mvynyane 2013-14 Temperate
MAP Ladysmith Maphophomeni Ladysmith
2014-15
Temperate
MJI Kokstad Mjila - Kokstad 2012-13 Temperate
Materials and methods (cont.): Localities
*
*
*

8. • Data collection: marketable root yield, unmarketable root
yield classes, dry mass, taste acceptability of small
informal panels
• Combined analysis of variance (SAS): cultivar, locality,
region
• Genotype x Environment analysis: AMMI model
(Genstat): cultivar * location
• Discriminant analysis (XLSTAT) to determine most
prominent characteristics
Materials and methods (cont.)

9. Analysis of Variance Table
Total Yield Marketable Yield
Source DF
Mean
Square Pr>F
Mean
Square Pr>F
Local 14 1297.05 <.0001 742.45 <.0001
Region 2 286.70 0.0018 649.66 <.0001
Rep(Local) 30 73.96 0.0201 42.40 0.0041
Cultivar 5 80.37 0.106 242.76 <.0001
Local*Cultivar 70 79.80 0.001 40.26 0.0007
Region*Cultivar 10 87.67 0.0349 76.26 0.0003
Error 150 43.38 21.45
Corrected Total 269
Results

10. Variable Minimum Maximum Mean
Taste score 1.3 4.6 2.5
Drymass% 16.2 35.8 25.5
Insect% 0.0 67.3 15.1
XXS% 0.0 25.6 6.5
Damaged% 0.0 19.9 5.7
Grooves% 0.0 30.0 5.1
XXL% 0.0 36.7 4.7
Veins% 0.0 55.0 4.3
Constrictions
% 0.0 20.0 3.6
Cracked% 0.0 26.3 2.9
Rat% 0.0 36.2 2.8
Rotten% 0.0 13.7 1.8
Curved% 0.0 22.0 1.7
Avg Weight
PerRoot (g) 130.7 514.3 242.5
Marketable% 21.2 86.4 59.1
Means across 15 sites
Total
yield t/ha
Mark
yield t/ha
199062.1 28.5a 199062.1 19.0a
Ndou 27.8a Ndou 17.8a
Monate 27.2ab Monate 15.8b
Bophelo 26.6ab Mvuvhelo 15.2bc
Mvuvhelo 25.9ab Bophelo 13.8cd
Impilo 24.8b Impilo 13.1d
Mean 26.8 15.8
CV% 24.6 29.33
Range
over loc’s
10.1-
37.9
5.0-
25.6
Blesbok (Control) at 8
sites produced lowest
Mark & Total yield

11. 10
15
20
25
30
35
40
199062.1 Bophelo Impilo Monate Mvuvhelo Ndou
TotalYield
Cultivars
RegionxCultivar Interaction Means
Coolsubtropical Subtropical Temperate
LSDp=0.05 = 6.97
0
5
10
15
20
25
30
199062.1 Bophelo Impilo Monate Mvuvhelo Ndou
MarketableYield
Cultivars
RegionxCultivar Interaction Means
Coolsubtropical Subtropical Temperate
LSDp=0.05 = 4.91

12. Genotype x environment interaction

13. Genotype x environment interaction (cont.)

14. 199062.1
Bophelo
Impilo
Monate
Mvuvhelo
Ndou
-4
-3
-2
-1
0
1
2
3
-4 -3 -2 -1 0 1 2 3
F2(36.86%)
F1 (50.98 %)
Centroids (axes F1 and F2: 87.84 %)
Centroids
F1 F2
Taste -0.136 -0.395
Constrictions -0.253 -0.137
Grooves -0.050 0.269
Veins -0.514 -0.202
Drymass% -0.185 0.710
XXS% 0.106 -0.123
XXL% 0.066 0.040
Cracked% 0.201 -0.241
Insect% 0.128 -0.056
Rat% 0.096 -0.229
Rotten% 0.119 -0.138
Damaged% -0.285 0.023
Curved% -0.300 -0.068
MarketableYield -0.248 0.212
WeightPerRoot -0.521 0.145
Marketable% -0.190 0.225
TotalYield -0.074 0.102
Taste
Constrictions
Grooves
Veins
Drymass%
XXS%
XXL%
Cracked%
Insect%
Rat%
Rotten%
Damaged%
Curved%
MarketableYield
WeightPerRoot
Marketable%
TotalYield
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0.75
1
-1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1
F2(36.86%)
F1 (50.98 %)
Variables (axes F1 and F2: 87.84 %)
Discriminant analysis
Ranking exercise to recommend cultivars per site

15. 1 ha production Ms Mmakgomu
Sokhulumi
Bronkhorstspruit
Mr Moyo
Winterveldt
Yield (Total sold excluding quantities consumed by
household)
13.9 tons 19.6 tons
Limpopo
Gauteng
• Mean 13.5 t/ha
• Mean 16.7 t/ha
Farmer yield

16. Vine dissemination and production 2015
• Vine dissemination during 2014/15 raised to
2.1 mil cuttings from 10 nurseries, ~ 75 ha
• 66% were orange-fleshed sweet potato

17. Conclusions
• Significant interaction of Locality*Cultivar and
Region*Cultivar
• Mean marketable yield of 15.8 t/ha
• Insect infestation was the most prevalent
unmarketable root yield class
• Veins, dry mass and avg root mass were the
main variables distinguishing cultivars
• Increased availability of vines/fresh produce
• Large potential for income generation on
informal market

18. Acknowledgements
• ARC-VOP team
• ARC Biometry unit
• Department of Agriculture collaboration with
on-farm trials
• Funding by ARC for trials; Dept Rural
Development for vine and production
enterprise project

19. Thank YouThank you