Open Agriculture. 2017; 2: 431–441 1 Introduction South Africa annually produces around 60,000 tons of sweet potato (DAFF 2014), a much lower production than most other countries in sub-Saharan Africa (FAOSTAT 2014). Notwithstanding, sweet potato is an important indigenized root crop in South Africa and a popular traditional crop in the northern subtropical regions of the country (Laurie et al. 2015b). The sweet potato industry in South Africa is notably different as there is, on one end, a small number of large commercial mechanized farmers and, on the other end, the crop features prominently in smallholder cropping systems delivering to the informal markets. Smallholder and subsistence farmers easily include sweet potato in their cropping programmes because of its versatility, ease to cultivate and hardiness. Additionally, many people are starting to note the value of orange cultivars as rich sources of provitamin A (Laurie et al. 2015b). This is of great importance since Vitamin A deficiency (VAD) in South Africa is a national public health problem with 43.6% of one- to nine-year-olds being vitamin A deficient (Shisana et al. 2013). The same survey also indicated that food security is at an unfavourable level, with 28.3% of the population at risk of hunger and 26.0% already experience hunger. Based on these alarming statistics, sweet potato is promoted for food and nutrition security. While the estimated informal market of 25,000 – 30,000 t for sweet potato brings an opportunity for income generation and enterprise development, there is a large potential for processing sweet potato into various products, such as biscuits, doughnuts, juice and chips that can be processed on kitchen-scale (Laurie et al. 2015b, but may be scaled to commercial size with higher sweet potato production. Since 1995, the ARC-VOP breeding programme has been focussing on high yield, good root quality, adaptability, high dry mass and sweet taste. Furthermore, in 2003, β-carotene became the major breeding goal of the programme. Cultivars released include Ndou and Monate (2003), Impilo (2007), Bophelo (2011), and Mvuvhelo (2013), while a line from the International Potato Centre https://doi.org/10.1515/opag-2017-0047 received December 10, 2016; accepted June 5, 2017 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. Keywords: AMMI, discriminant analysis, sweetpotato, yield Research Article Sunette Laurie*, Frikkie Calitz, Musa Mtileni, Whelma Mphela, Sidwell Tjale Performance of informal market sweet potato cultivars in on-farm trials in South Africa *Corresponding author: Sunette Laurie, Agricultural Research Council- Vegetable and Ornamental Plants (ARC-VOP), Pretoria, South Africa; E-mail: slaurie@arc.agric.za Musa Mtileni, Whelma Mphela, Sidwell Tjale, Agricultural Research Council-Vegetable and Ornamental Plants (ARC-VOP), Pretoria, South Africa Frikkie Calitz, Agricultural Research Council-Biometry, Pretoria, South Africa Open Access. © 2017 Sunette Laurie, et al., published by De Gruyter Open. This work is licensed under the Creative Commons Attribution- NonCommercial-NoDerivs 3.0 License.