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Laurie S.,Roodeplaat Vegetable and Ornamental Plant Institute | Faber M.,Non Communicable Diseases Research Unit | Adebola P.,Roodeplaat Vegetable and Ornamental Plant Institute | Belete A.,University of Limpopo
Food Research International | Year: 2015

South Africa has a diverse population, with some pockets of society being in a first world setup and other pockets in a third world impoverished setup. Food provision in impoverished societies is particularly crucial. Sweet potato (Ipomoea batatas (L.) Lam.) is a hardy crop and prominent in ensuring household food security; through its rich supply of energy, high yield potential and market value. In addition, orange-fleshed cultivars in particular are prominent in combating vitamin A deficiency due to high content of naturally bio-available β-carotene. This paper reviews interventions with regard to biofortification of sweet potato in South Africa towards addressing food and nutrition security. The focus was on the development of biofortified (high β-carotene content) cultivars and screening procedures for desired varietal traits; assessment of β-carotene, anti-oxidant and mineral content and the processing potential of orange-fleshed cultivars. Efficacy of orange fleshed sweet potato to improve vitamin A status was shown and positive effects of household production of orange-fleshed sweet potato, in conjunction with other β-carotene rich vegetables, on dietary intake, vitamin A status and food security were recorded. Dissemination efforts were initially focused on home gardens, which gradually expanded to subsistence production and enterprises. During 2014/15, over 1 million cuttings were disseminated and 5 to 40 small-scale commercial farmers in six provinces planted 0.25 to 1. ha of orange-fleshed sweet potato as means for income generation. In order to exploit the nutritional benefits of sweet potato and its potential to reduce vitamin A malnutrition and food insecurity, it is recommended that policy makers set directives to incorporate orange-fleshed sweet potato in government programs related to health, rural development, social development and agricultural production. There is a great need for investment in promotion of orange-fleshed sweet potato, particularly to consumers and retailers. Private-public partnerships and investment by private companies will be crucial for upscaling the impact of orange-fleshed sweet potato on food and nutrition security. © 2015 Elsevier Ltd.


Laurie S.M.,Roodeplaat Vegetable and Ornamental Plant Institute | Calitz F.J.,Agricultural Research Council | Adebola P.O.,Roodeplaat Vegetable and Ornamental Plant Institute | Lezar A.,Roodeplaat Vegetable and Ornamental Plant Institute
South African Journal of Botany | Year: 2013

A total of 57 sweet potato accessions, consisting of 51 South African land races and six local cultivars, were subjected to characterization in a glass house and in follow-up field experiments. The accessions were morphologically characterized using the Bioversity International descriptors and, in addition, screened for drought and heat tolerance. Significant differences were observed for the following drought-heat screening parameters: number of days to severe wilting and number of severely wilted plants. A number of land races showed tolerance to both drought and heat, namely A3026, A3027, A2316 and A46. The multivariate cluster analysis and principal component analysis divided the 57 accessions into three groups consisting of 17, 21 and 19 accessions, respectively. The commercial varieties were all allocated to group 3, except the old cultivar Mafutha, which was in group 1. The most important characters for distinction of the accessions were leaf outline, leaf lobe type, leaf lobe number, and shape of the central leaf lobe. The study provided comprehensive information concerning locally available sweet potato germplasm and is of vital importance for advancement in the sweet potato improvement program in South Africa. The information will also be useful to SASHA (a regional network for sweet potato breeding), ensuring wider utilization of these germplasms within Sub-Saharan Africa. © 2012.


PubMed | University of Pretoria, a Non communicable Diseases Research Unit and Roodeplaat Vegetable and Ornamental Plant Institute
Type: Journal Article | Journal: Ecology of food and nutrition | Year: 2016

Sociodemographic, living standard measure, consumption of vegetables and fruit, and dietary diversity in relation to household food security were assessed. Using a hunger score, households were categorized as food secure (n = 125) or food insecure (n = 273). Food secure respondents had a higher mean dietary diversity score (3.98; 95%CI [3.79, 4.18] versus 3.65; 95% [CI 3.53, 3.77]), were more likely to eat vitamin A-rich foods (OR 1.15; 95% CI [1.05, 1.26]), a more varied diet (DDS 4, OR 1.90; 95% CI [1.19, 3.13]), and vegetables daily (OR 3.37; 95% CI [2.00, 5.76]). Cost limited daily vegetable/fruit consumption in food insecure households. Respondents with 8 years of schooling were more likely (OR 2.07; 95% CI [1.22, 3.53]) and households receiving social grants were less likely (OR 0.37; 95% CI [0.19, 0.72]) to be food secure. Results highlight the association between dietary diversity and household food security.


Maboko M.M.,Roodeplaat Vegetable and Ornamental Plant Institute
Acta Horticulturae | Year: 2013

Ideal plant population can lead to optimum yields, whereas too high or too low plant densities can result in relatively lower yields and quality. The objective of this study was to determine the combined effect of plant densities and leaf harvesting frequencies on yield of hydroponically grown mustard spinach. Mustard spinach plantlets were transplanted 21 days after seeding, utilizing a gravel-film technique hydroponic system. Eight treatment combinations were used, namely four plant densities (10,16, 20 and 25 plants/m2) combined with two leaf harvesting frequencies (after every 7 and 14 days). Leaf area, fresh and dry mass, and number of leaves were measured from four weeks after transplanting. Total number of inflorescences and bolted plants were also recorded. The results show that plant densities and harvesting frequencies, both, affected leaf area, leaf fresh mass and leaf dry mass per m2 planted. Harvesting frequency of 14 days significantly improved leaf area, leaf fresh and dry mass as well as number of inflorescences and bolted plants compared to 7 day frequencies. Conversely, leaf number was higher at a harvesting frequency of 7 days. Leaf fresh mass, area, dry mass and number of leaves at a plant density of 25 plants/m2 improved significantly compared to a plant density of 20, 16 and 10 plants/m2. An increase in plant population resulted in an increase in the number of inflorescences and bolted plants. Plant density of 25 plants/m2 combined with a harvesting frequency of 14 days improved yield of mustard spinach significantly.


Maboko M.M.,Roodeplaat Vegetable and Ornamental Plant Institute | Du Plooy C.P.,Roodeplaat Vegetable and Ornamental Plant Institute
Acta Horticulturae | Year: 2013

A study was conducted in a shade-net structure to evaluate the effect of early decapitation combined with high density plantings on tomato yield and quality in a hydroponic system. Plants were grown in a closed hydroponic (gravel-film technique) system using granite rocks as a substrate. The growing points of all plants were removed between the second and third inflorescence at 30-35 days after transplanting with two leaves remaining above the second inflorescence. In the first experiment (Exp. 1), plants were subjected to four plant densities i.e., 8, 16, 20 and 25 plants/m2 using tomato cultivar 'FA593'. In the second experiment (Exp. 2), two tomato cultivars, i.e., 'FA593' and 'Rodade' were used at four plant densities i.e., 10, 16, 20 and 25 plants/m2. For each experiment a randomised complete block design was used with five replicates. Total, marketable and unmarketable yields, as well as physiological disorders were recorded. In Exp. 1, results showed highest total yield and number of marketable fruits per unit area at a spacing of 25 plants/m2 although not significantly different to 20 plants/m2. Results in Exp. 2 showed similar results with significantly higher values of all variables at the highest density (25 plants/m2). The incidence of fruit cracking decreased with an increase in plant density. Cultivar 'FA593' produced significantly higher total yield, marketable yield, number of marketable fruits, fruit exhibiting cracking and blossom-end rot as compared to cultivar 'Rodade'. Results demonstrate that tomatoes pruned back to two trusses, combined with high density planting in a closed hydroponic system can achieve high yield of good quality with a shortened growth season.


Oyeyinka S.A.,Durban University of Technology | Singh S.,Durban University of Technology | Adebola P.O.,Roodeplaat Vegetable and Ornamental Plant Institute | Gerrano A.S.,Roodeplaat Vegetable and Ornamental Plant Institute | Amonsou E.O.,Durban University of Technology
Carbohydrate Polymers | Year: 2015

Abstract The physicochemical properties of starches extracted from five bambara genotypes were investigated. Bambara starch granules were predominantly oval shaped with a smooth surface and an average size of 26 ± 0.2 μm. The amylose contents (20-35%) varied significantly among genotypes. X-ray diffraction revealed the C-type pattern for all starches with relative crystallinity range: 29-35%. FTIR spectra of bambara starches showed variable peak intensities at 2931, 1655 and 860 cm-1, which corresponds to CH stretching, H2O bending vibrations and CO stretching, respectively. Bambara genotype with the highest amylose content showed the lowest intensity at wavenumber 2931 cm-1. With the exception of oil absorption which was similar, swelling power, water absorption and paste clarity of starches were significantly different among genotypes. Genotype with high amylose content showed restricted swelling, low paste clarity and great ability to absorb water. All bambara starches displayed a shear thinning behaviour (n < 1). © 2015 Elsevier Ltd.


Faber M.,Nutritional Intervention Research Unit | Oelofse A.,University of Pretoria | Van Jaarsveld P.J.,Nutritional Intervention Research Unit | Wenhold F.A.M.,University of Pretoria | Jansen Van Rensburg W.S.,Roodeplaat Vegetable and Ornamental Plant Institute
South African Journal of Clinical Nutrition | Year: 2010

Objectives: The objectives of this study were to determine the availability of, access to and nutrition-related uses of African leafy vegetables in rural and urban households; and to determine the β-carotene content of the dominant African leafy vegetable. Design: The study consisted of a qualitative explorative phase (feld walks, semi-structured interviews with key informants, focus group discussions) at two rural sites; and a quantitative household survey (questionnaire) at two rural and one urban site. Amaranth leaves were analysed for β-carotene content. Setting and subjects: The household survey included households at a rural site in Limpopo province (n = 100); and a rural (n = 101) and urban (n = 391) site in KwaZulu-Natal province, South Africa. Results: A variety of edible plants were identifed during feld walks at the two rural sites. Focus group discussions narrowed this down to ten plants at the rural Limpopo site and six at the rural KwaZulu-Natal site. The most popular leaves were amaranth (Amaranthus spp), spider plant (Cleome gynandra), wild watermelon (Citrullus lanatus) and blackjack (Bidens spinosa), consumed individually or mixed with other leaves. Rural households procured leaves mostly from the wild whereas urban households relied more on informal markets. In Limpopo, leaves were dried and stored for consumption during winter. KwaZulu-Natal households considered African leafy vegetables food for the poor. Leaves were boiled in salted water, or steamed and then fried in oil. Fried and boiled amaranth leaves contained 627 and 429 μg retinol activity equivalents/100 g respectively. Conclusions: Availability of, access to and nutrition-related uses of African leafy vegetables are context-specifc, with inter-and intraprovincial rural/urban differences. Information collected during small studies within a specifc area can therefore not be generalised for the overall South-African population. Amaranth can potentially contribute signifcantly to vitamin A requirements of nutritionally vulnerable communities.


Gerrano A.S.,Roodeplaat Vegetable and Ornamental Plant Institute | Van Rensburg W.S.J.,Roodeplaat Vegetable and Ornamental Plant Institute | Adebola P.O.,Roodeplaat Vegetable and Ornamental Plant Institute
South African Journal of Plant and Soil | Year: 2015

Amaranthus species plays an important role in sustaining food security and alleviation of malnutrition in South Africa. A number of Amaranthus genotypes have been collected and conserved in the gene bank of the ARC-Roodeplaat Vegetable and Ornamental Plant Institute, South Africa. It is important to genetically evaluate germplasm and select superior parental lines for utilisation in future Amaranthus breeding in the country. Thirty-two Amaranthus genotypes were therefore selected and evaluated in field plantings for quantitative morphological traits using a randomised complete block design across two seasons. Genetic parameters were estimated for 14 phenotypic traits and a considerable amount of genetic variability was observed. Characters such as thousand seed weight, dry biomass, number of leaves, leaf length and panicle length showed high heritability estimates and genetic advance. The Pearson correlation coefficient for the traits showed that there were significant (P ≤ 0.01) correlations among some of the phenotypic traits. Cluster analysis grouped the genotypes into six different groups and a singleton based on their genetic similarity. The clustering of the genotypes based on their genetic similarity will help in the identification of diverse parents for use in the breeding programme. © 2015 © Southern African Plant & Soil Sciences Committee.


Laurie S.M.,Roodeplaat Vegetable and Ornamental Plant Institute | van Jaarsveld P.J.,Nutritional Intervention Research Unit | Faber M.,Nutritional Intervention Research Unit | Philpott M.F.,The Water Council | Labuschagne M.T.,University of the Free State
Journal of Food Composition and Analysis | Year: 2012

The content of trans-β-carotene and selected minerals was determined in 12 sweetpotato (Ipomoea batatas) varieties produced at 4 agro-geographical production sites in South Africa. All 9 orange-fleshed varieties have the potential to contribute ≥100% of the recommended dietary allowance of 4-8 year-old children for vitamin A, 27% for magnesium, 15% for zinc and 11% for iron. Orange-fleshed varieties were superior to cream-fleshed ones in calcium and magnesium content. The trans-β-carotene content of the varieties varied over the geographical sites. The mean content in the 9 orange-fleshed varieties was between 5091 and 16,456 μg/100. g fresh weight. The mineral content in fresh roots of the 12 varieties ranged from 34 to 63. mg/100. g for calcium, 15 to 37. mg/100. g for magnesium, 28 to 51. mg/100. g for phosphorus, 191 to 334. mg/100. g for potassium, 0.73 to 1.26. mg/100. g for iron, and 0.51 to 0.69. mg/100. g for zinc. Variation within varieties over geographical sites could be ascribed to differences in soil mineral content, soil pH and the interaction of these. The variation in nutritional content of sweetpotato indicated here, needs to be considered in varietal selection for different production sites and in calculating nutrient contribution of sweetpotato toward dietary intake. © 2012 Elsevier Inc.


PubMed | Durban University of Technology and Roodeplaat Vegetable and Ornamental Plant Institute
Type: | Journal: Carbohydrate polymers | Year: 2015

The physicochemical properties of starches extracted from five bambara genotypes were investigated. Bambara starch granules were predominantly oval shaped with a smooth surface and an average size of 260.2m. The amylose contents (20-35%) varied significantly among genotypes. X-ray diffraction revealed the C-type pattern for all starches with relative crystallinity range: 29-35%. FTIR spectra of bambara starches showed variable peak intensities at 2931, 1655 and 860cm(-1), which corresponds to CH stretching, H2O bending vibrations and CO stretching, respectively. Bambara genotype with the highest amylose content showed the lowest intensity at wavenumber 2931cm(-1). With the exception of oil absorption which was similar, swelling power, water absorption and paste clarity of starches were significantly different among genotypes. Genotype with high amylose content showed restricted swelling, low paste clarity and great ability to absorb water. All bambara starches displayed a shear thinning behaviour (n<1).

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