Assessment of food gardens as nutrition tool in primary schools in South Africa

Objectives: To assess knowledge, perceptions and practices on food production  amongst learners and educators, gardening activities and management of school food gardens in schools participating in the National School Nutrition Programme.Design: Cross-sectional survey.Setting: Ten purposively selected primary schools in each of the nine provinces of South Africa (total: n = 90).Subjects and outcome measures: Questionnaire data were collected from the garden administrators (n = 66), garden workers (n = 55), educators (n = 687) and learners (n = 2 547). A checklist was completed for the school garden (n = 66) by  observation.Results: Sixty-six (73%) schools had a food garden, varying in size (100 m2 – 6  000 m2). A variety of vegetables, but few fruit, were grown. Problems experienced  with gardens were mostly lack of funds (59%), tools and infrastructure (47%),  garden workers (53%) and technical support (50%). Few schools received external funding for food gardens. In 50% of gardens, crops were growing for > 6 months, and 30% of gardens provided fresh produce for school meals more than twice a week. Fifty-four percent (54%) of learners were involved in school gardens, and 67% had food gardens at home. Attitudes of learners and educators towards both food  gardening and eating vegetables and fruit were generally positive; 68.4% of learners and 86.4% of educators indicated they like to eat vegetables every day.Conclusions: School food gardens as a vehicle for improving nutrition should be strengthened through training of educators and garden personnel, and support by external role players and policy directives are needed to enhance sustainability.Keywords: agriculture, National school nutrition program, school food garden

Total β-carotene content of orange sweetpotato cultivated under optimal conditions and at a rural village

At community level, sweetpotato is often cultivated in marginal soils, with low agricultural inputs and is harvested when needed. Total β-carotene content of orange sweetpotato harvested four, five and six months after planting at optimal cultivation conditions and at a rural village was determined. Compared to those produced under optimal conditions, sweetpotato produced under rural village conditions were smaller, had higher β-carotene content and required a smaller serving size to provide 100% of the dietary vitamin A requirements. Harvesting at four, five and six months after planting at a rural village showed gradual increases in β-carotene content; no change was observed under optimal conditions. Differences in β-carotene content due to harvesting time and management level should be considered in food-based interventions addressing vitamin A deficiency.Keywords: Provitamin A content, orange sweet potato, cultivation conditionsAfrican Journal of Biotechnology Vol. 12(25), pp. 3947-395

Analysis of the Nutritional Composition and Drought Tolerance Traits of Sweet Potato: Selection Criteria for Breeding Lines

Sweet potato is an important world staple with the potential to address hunger and malnutrition. The Agricultural Research Council of South Africa has led sweet potato breeding efforts in the country since 1952 and released several important cultivars. More detailed quality assessments are necessary in addition to general breeding criteria. The present study investigated sweet potato cultivars and elite clones for (1) their nutritional composition; (2) biochemical reaction to drought stress; (3) correlate biochemical reaction to root yield for possible identification of screening methods for drought tolerance in sweet potato. Orange-fleshed cultivars, in particular Bophelo, had superior contents of Fe, Zn, Mg, Ca, Mn, and dietary fiber. Cream-fleshed cultivars, particularly Ndou, were higher in starch and carbohydrate. When sweet potato cultivars were subjected to drought stress, significant changes were noted in most antioxidant enzymes, chlorophyll and proline concentrations, and 13C discrimination. All of these showed significant correlations with root yield. For screening of drought tolerance, the determination of nitrate reductase, proline, and chlorophyll concentrations at 60 days after planting are recommended. Ndou was less affected by drought stress. Bophelo and Ndou, which are gaining popularity on the informal market, have superior nutritional value and are good cultivar choices for food security and addressing malnutrition

Influence of Harvesting Stages on Phytonutrients and Antioxidant Properties of Leaves of Five Purple-Fleshed Sweet Potato (<i>Ipomoea batatas</i>) Genotypes

Sweet potatoes (Ipomoea batatas) are highly profitable, contribute to food security, and their leaves rich in phytonutrients. This study examined the optimal leaf harvesting stage by harvesting newly formed leaves (leaves 1 to 5) to achieve the highest concentration of carotenoids, phenolic compounds, antioxidant properties and mineral content. Leaves of five purple-fleshed sweet potato genotypes ‘2019-11-2’ and ‘2019-1-1’, ‘Purple-purple’, and from the USA ‘08-21P’ and ‘16-283P’ were harvested based on tuber life cycle [vegetative 8 weeks after planting (VS-8WAP), tuber initiation (TIS-12WAP), and tuber maturation phases (TMS-16WAP)]. At the 8WAP stage, leaves of genotype ‘2019-11-2’ had the highest concentrations of cyanidin-caffeoyl-sophoroside-glucoside (17.64 mg/kg), cyanidin-caffeoyl-feruloyl-sophoroside-glucoside (41.51 mg/kg), peonidin-caffeoyl-hydroxybenzoyl-sophoriside-glucoside (45.25 mg/kg), and peonidin caffeoyl-feruloyl-sophoriside-glucoside (24.47 mg/kg), as well as antioxidant scavenging activity. In contrast, ‘Purple-purple’ harvested at TIS-12WAP showed the highest concentration of caffeoylquinic acid derivatives. Zeaxanthin, lutein, all trans-β-carotene, and cis-β-carotene are the most abundant carotenoids in genotype ‘08-21P’ at VS-8WAP. As a result, local genotypes ‘2019-11-2’ harvested at 8WAP and ‘Purple-purple’ harvested at 12WAP are potential sources of anthocyanins and caffeoylquinic acid derivatives. Conversely, USA’s genotype ‘08-21P’ at the VS-8WAP stage is an excellent source of carotenoids. The leaves of USA’s ‘08-21P’ genotype and the local ‘2019-11-2’ genotype at TMS-16WAP exhibited the highest content of Fe and Mn, respectively. The study identified the optimal leaf stage for consumption of leaves and for use as a functional ingredient

Comparison of Caffeoylquinic Acids and Functional Properties of Domestic Sweet Potato (Ipomoea batatas (L.) Lam.) Storage Roots with Established Overseas Varieties

Root samples of sweet potato varieties originating from South Africa (&lsquo;Ndou&rsquo;, &lsquo;Bophelo&rsquo;, &lsquo;Monate&rsquo;, and &lsquo;Blesbok&rsquo;), the USA (&lsquo;Beauregard&rsquo;), and Peru (&lsquo;199062.1&prime;) were analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/QTOF/MS) and chemometrics to characterize and compare the locally developed varieties with well-known established overseas varieties. The highest total phenol content was detected in &lsquo;Bophelo&rsquo;, followed by &lsquo;Beauregard&rsquo; and Peruvian variety &lsquo;199062.1&rsquo;. The Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) model classified the storage roots of six sweet potato varieties into two clusters. In the OPLS-DA scatter plot, one cluster, which included Peruvian variety &lsquo;199062.1&rsquo;, was separated from the others. L-tryptophan and 3-caffeoylquinic acid (CQA) showed variable importance in projection (VIP) scores greater than 1.5. Based on the OPLS-DA-S-plot, L-tryptophan separated the other varieties from Peruvian variety &lsquo;199062.1&rsquo;. Peruvian variety &lsquo;199062.1&rsquo; contained higher concentrations of CQA (1,3-diCQA, 1,4-diCQA, 3,5-diCQA, 4,5-diCQA, 3-CQA, and 5-CQA) and 5-hydroxy-6-methoxycoumarin 7-glucoside than other varieties. Among all sweet potato varieties analyzed, Peruvian variety &lsquo;199062.1&prime; showed the highest ferric reducing antioxidant power (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging activity, and [2,2&prime;-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] scavenging activity. Among the local sweet potato varieties, &lsquo;Bophelo&rsquo; has the greatest potential for commercialization as it is the richest source of CQA

Selection of Sweetpotato Parental Genotypes Using Simple Sequence Repeat Markers

Knowledge of the genetic diversity and genetic relationship is important in crop improvement. The objective of this study was to determine the genetic diversity of 31 sweetpotato genotypes and furthermore to select distantly related individuals for breeding of superior parental clones. The genotypes (sourced from the Agricultural Research Council, South Africa) originating from Africa and American continent were genotyped using eight highly polymorphic SSR markers. The SSR markers generated a total of 83 putative alleles. The polymorphic information content (PIC) of the tested simple sequence markers varied from 0.73 to 0.91, with a mean of 0.85. At least 11 different alleles were found in 8 loci within the population, with 7 effective alleles per locus. Although high diversity was found among the genotypes, genetic distances among the genotypes were relatively low. Cluster analysis revealed the existence of three distinct genetic groups, and the clustering patterns follow to some extent the geographic origin and pedigree of the genotypes. High gene flow was observed among different sweetpotato accessions. The selected SSR markers were found to be highly polymorphic with high discriminatory power for genetic characterization studies and are useful genomic tool to complement phenotyping of sweetpotato genotypes. Two heterotic groups were found in the study. The heterotic group A was composed of 14 genotypes mainly of South African origin, while the heterotic group B consisted of 17 genotypes of American origin. The two distinct groups were important for the selection of breeding clones that were distantly related to be used as parental clones in the advancement of traits of interest

Genetic variability in cowpea (Vigna unguiculata (L.) Walp.) genotypes

Information on genetic variability among the existing cowpea genotypes will increase the efficiency of the cowpea improvement. Field experiments were conducted at the Agricultural Research Council–Roodeplaat Vegetable and Ornamental Plant Institute in South Africa, in 2011 and 2012, to estimate the level of phenotypic variability among a collection of 25 cowpea genotypes. The experiment was laid out in a randomised complete block design with three replications. Sixteen phenotypic markers were recorded. Analysis of variance for the phenotypic traits revealed that differences among genotypes were highly significant for all traits. This indicated the high level of genetic variability among the cowpea genotypes studied. Genetic and phenotypic coefficient of variation, and broad-sense heritability were estimated for all phenotypic traits. The first five principal components showed 79.30% of the total variability among the genotypes. Pod length, leaf area, leaf area index and number of seeds per plant contributed mainly to PC1 and leaf number, plant height, dry biomass and fresh biomass contributed mainly to PC2. Cluster analysis of the phenotypic traits resulted in five distinct groups of genotypes. The phenotypic traits therefore provide a useful measure of genetic distances among the cowpea genotypes and will enable the identification of potential parental materials for future breeding efforts. Genotypes IT93K129-4, Fahari, Glenda and Veg cowpea Dakama Cream were associated with desirable grain yield characteristics and are recommended as suitable parental lines for improvement of grain production. Genotypes 5431, Tatro mix, Kisumu mix and Okalulenu were identified to possess good vegetative traits and are also recommended for use as suitable parents when breeding for leafy vegetable or for fodder production.Keywords: heritability, phenotype, principal component analysis, varianc