S. M. Laurie

The use of sensory attributes, sugar content, instrumental data and consumer acceptability in selection of sweet potato varieties

BACKGROUND As eating quality is important for adoption of new varieties, nine orange-fleshed and three cream-fleshed sweet potato varieties were assessed for sensory characteristics, dry mass and free sugar content, instrumental texture and colour and consumer acceptability (n =  216) in a peri-urban South African setting. RESULTS Cream-fleshed varieties were higher in yellow-green colour and sweet potato-like flavour and lower in graininess. Orange-fleshed varieties were higher in pumpkin-like flavour, orange colour, discolouration and sucrose content. Partial least squares regression analysis showed that the most accepted varieties (Impilo, Excel, Resisto, 2001_5_2, Serolane, W-119 and Monate) were associated with sweet flavour, dry mass and maltose content, while the least accepted varieties (Beauregard, Khano and 1999_1_7) were associated with wateriness. Pearson correlation analysis highlighted correlations of sensory attributes yellow and orange with instrumental colour measurements (colour a* and colour b*), instrumental firmness with sensory firmness, dry mass with sensory wateriness, and maltose content with sensory sweet and sweet potato-like flavour. The varieties were clustered into three groups. Consumer acceptability for eating quality correlated with maltose content, dry mass and sweet flavour. CONCLUSION Chemical and instrumental measurements were identified to evaluate key attributes and will be useful in the intermediate phases of sweet potato varietal development.

Availability of, access to and consumption of fruits and vegetables in a peri‐urban area in KwaZulu‐Natal, South Africa

Availability and consumption of fruits and vegetables were assessed in peri-urban households in KwaZulu-Natal Province, South Africa. Caregivers of 400 randomly selected grade 6 and 7 learners were interviewed using a questionnaire that included unquantified food frequency questions. Using a repeated 24-h dietary recall, dietary intake was quantified for learners, caregivers and 2- to 5-year-old children in the household. Usual household fruit and vegetable consumption was expressed over three Living Standard Measure (LSM) categories. Average per capita intake of fruit and/or vegetables was 99 g for 2- to 5-year-old children and 124 g for caregivers. For consumers, fruits and/or vegetables contributed towards total dietary intake of fibre (16-21%), calcium (13-21%), vitamin A (27-31%) and vitamin C (47-62%). For households not consuming fruits (n = 297) and vegetables (n = 178) daily, cost was the major constraint (≥75%). Of all households, 52% had fruit trees and 25% had a vegetable garden. Animals destroying vegetables was the major constraint to 59% of vegetable growers. Household consumption of fruits and vegetables increased over the LSM categories. Caregivers in the higher LSM group more likely used printed material for information on healthy eating, had fruit trees, were confident about vegetable gardening and sold some of their produce. To enable peri-urban populations of low socio-economic status to consume more frequently a bigger variety of fruits and vegetables, the cost of purchasing these food items needs to be addressed by government and business sector. Households should further receive support to overcome constraints which hamper the success of home gardens.

Initiation and First Results of a Biofortification Program for Sweet Potato in South Africa

Orange-fleshed sweet potato, high in provitamin A carotenoids, were introduced to Africa from the United States, but there was a shortage of varieties with desirable traits for South African conditions, namely, stable yield, good total carotenoid content, and good taste. Desirable characteristics were combined annually through the polycross method using parents selected for specific traits, followed by clonal selection phases and multi-location advanced yield trials. Genotype by environment analysis of advanced lines indicated two locally bred lines, 1998-21-1 (released as “Impilo”) and 1999-1-7, as the best. Other useful clones were 1999-6-1 (released as “Khano”) and U.S. variety “Resisto.” These were recommended for use in food-based approaches to address vitamin A deficiency. In addition, three new promising lines were identified, viz., 2001-5-2, 2000-6-1, and 2000-10-7, which needed to be evaluated in multi-location trials to determine their adaptability. Future breeding efforts could concentrate on higher levels of total carotenoids and stable high yields, and in addition, on tolerance to drought and Alternaria stem blight.

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.

Effect of different types of mulching and plant spacing on weed control, canopy cover and yield of sweet potato (Ipomoea batatas (L.) Lam).

The aim of the study was to determine the effects of mulching, plant spacing and other control measures on effectiveness of weed control, canopy cover and sweet potato yield. The cultivar Blesbok was planted in a randomized complete block design where seven treatments were replicated four times. Field trials were established at the Agricultural Research Council Roodeplaat Vegetable and Ornamental Plant Institute in Pretoria, South Africa during 2006 and 2007. Seven treatments were applied: 1) HW = Hand weeding, 2) NS = Narrow plant spacing (0.5 m between the rows and 15 cm between plants), 3) CO = Organic mulch (compost), 4) PL = Inorganic mulch (black plastic), 5) E*F = Eptam (EPTC; Thiocarbamate) followed by Fusilate (fluazifop-p-butyl), 6) L*F = Afalon (Linuron) followed by Fusilate (fluazifop-p-butyl), and 7) CN = Control (untreated plot). Organic mulch (compost) was omitted in the second trial as it will be Original Research Article Laurie et al.; AJEA, 5(5): 450-458, 2015; Article no.AJEA.2015.044 451 beneficial for both weeds and the crop making it difficult to control the weeds. Instead, grass straws (ST) and newspaper (NP) mulches were added. Narrow row spacing, hand weeding, plastic mulch, and newspaper mulch outperformed the other treatments and obtained more than 90% canopy cover by 5 weeks after planting. Effective reductions in weeds were detected with plastic and newspaper mulched plots and was similar to the hand-weeded treatment, followed by narrow spacing. Plots with newspaper mulch and narrow spacing produced marketable yields similar to the hand-weeded treatment. Inorganic mulching and narrow plant spacing were the most effective weed management treatments. Newspaper mulch seems to be a viable option for small holder farmers to control weeds in sweet potato plantings, eliminating the cost of labour to conduct hand weeding. Compost and grass mulch should not be adopted for weed control since these did not control weeds effectively.

Dietary Diversity and Vegetable and Fruit Consumption of Households in a Resource-Poor Peri-Urban South Africa Community Differ by Food Security Status

ABSTRACT 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.

Agronomic performance of new cream to yellow-orange sweetpotato cultivars in diverse environments across South Africa

Sweetpotato is grown in diverse environments of South Africa by both commercial and subsistence farmers. The aim of the present study was to assess the stability, agronomic performance and palatability of new ARC cultivars bred for the informal market, and to make cultivar recommendations. Eight new cultivars with cream to yellow-orange flesh were evaluated in multi-environment trials using a randomised complete block design in six provinces. Data were recorded on root yield, percentage dry mass, palatability and vine vigour. An additive main effects and multiplicative interactions model was employed for data analysis. New cultivars with high potential were Ndou, Letlhabula and Monate, with root yields similar to or slightly lower than the commercial control cultivar Blesbok. Ndou and Monate had vigorous vine growth, high dry mass and good end-user acceptability and offered the best combination of important traits for the informal market. Letlhabula seemed more suitable for the commercial market owing to lower dry mass. The new improved cultivars will be advantageous, firstly, to farmers as a result of high yield and, secondly, to consumers owing to better palatibility.

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.

Performance of informal market sweet potato cultivars in on-farm trials in South Africa

Abstract Several new sweet potato cultivars have been released in South Africa from 2004 until 2011 with varietal traits suitable for the informal market. This paper reports on results of on-farm trials conducted to evaluate the cultivars in broader agro-ecologies in the country. The trials were conducted at 15 localities across the 2011/12 to 2014/15 planting seasons including six cultivars with varying flesh colours. Data collection included marketable and unmarketable storage root yield classes, dry mass, and taste acceptability. The sites were representative of cool subtropical and warm temperate regions. Statistical analysis included ANOVA, AMMI, Discriminant analysis (DA) and Principal component analysis (PCA). Significant effects were detected for locality*cultivar and region*cultivar interactions for total and marketable yield, and for cultivar only for marketable yield. The factor region was not significant. The mean marketable yield ranged from 13.1 to 19.0 t/ha, being highest for 199062.1 and Ndou, while Bophelo had average stable yield over a broad range of environments. The most prevalent unmarketable class was weevil damage (15.1%). The study demonstrated PCA and DA as quick analytical tools to associate quality traits with cultivars to facilitate cultivar recommendations. Bophelo and Ndou had been sold with success on local informal markets and have large potential to be promoted wider.

Employing the GGE SREG model plus Elston index values for multiple trait selection in sweetpotato

Sweetpotato is a good source of energy, easy-to-grow and hardy and thus useful in contributing to food security. The current study aimed at identification of the best sweetpotato varieties for multiple desirable traits such as good yield, adaptability (including vine vigor) and tastiness (high dry mass content; taste). Ten South African sweetpotato varieties were evaluated during the period 2002/3–2007/8 at six locations each over two seasons. The sites regression model (SREG) of the genotype plus genotype by environment interaction (GGE) biplot analysis was performed with GenStat to determine stability and adaptability of the varieties. Subsequently, multiple trait selection was performed by using the ranking from Elston index selection. To enable inclusion of varietal stability in multiple trait selection, a stability value was calculated. High yielding varieties included Blesbok, Monate, Ndou and Letlhabula, of which Monate and Letlhabula had stable performance. The advantage, particularly for resource-poor farmers, of a specifically adapted, responsive variety such as Ndou, is the ability to respond to changes in the environment. Based on multiple trait selection varieties Ndou and Monate were recommended for production. The results present an innovative use of Elston index selection, including a stability value, in combination with GGE SREG for recommending varieties with multiple desirable traits. The recommended varieties are of significance for future use to improve food security.