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Despite the development of quality protein maize (QPM) genotypes with increased lysine and tryptophan levels, there is still a controversy on the yield potential of QPM genotypes compared to non-QPM genotypes. The objective of this study was to compare the QPM hybrids with non-QPM hybrids for grain yield and related traits and to determine if the QPM trait caused yield reduction in tested environments. A total of 126 hybrids were developed by crossing 32 inbred lines (22 QPM and 10 non-QPM) with two QPM and two non-QPM testers, using a line x tester design, and these were evaluated with four hybrid checks (two QPM and two non-QPM) at 13 locations in South Africa and Zimbabwe. Significant differences were observed among the hybrids for almost all the traits, indicating that superior hybrids could be identified and selected. Significant genotype by environment interaction effect was detected for almost all the traits which indicated that hybrids performed differently across the tested environments. When average yield for QPM and non-QPM was compared across the 13 sites, the yield reduction was 9.34% due to the QPM trait. Decreased ear placement and increased ear aspect could have contributed to this reduction. Yield reduction was 13% for the two QPM testers crossed with lines compared with means of crosses with two non-QPM testers. The best performing hybrid was a QPM genotype (entry 41), but only four of the top 20 hybrids were QPM. Though most crosses indicated a substantial yield loss due to the QPM trait, the top performing hybrid being a QPM indicates the possibility of yield potential improvement in QPM genotypes. [ABSTRACT FROM AUTHOR]

With its drought tolerant and protein-rich properties, Bambara groundnut [Vigna subterranea (L.) Verdc.], an indigenous African legume crop can contribute immensely to food security. This miracle crop is used as food and for the enhancement of soil fertility in South Africa. Knowledge on the genetic diversity and structure among the Bambara groundnut landraces can pave the way for the effective use and cultivation of this crop in southern Africa, especially South Africa. The aim of this study was to assess the genetic diversity and structure among Bambara groundnut landraces collected across South Africa and compared to a limited number of accessions from southern Africa using SSR markers. Seventy-eight Bambara groundnut accessions were genotyped using 19 Bambara specific SSR markers. SSR loci explored in this study, were all polymorphic. A total of 127 alleles were detected with a mean of 6.7 alleles per locus. Allele diversity and frequency among genotypes varied from 0.21 to 0.85 with an average of 0.62 per locus. Genetic variation as described by the analysis of molecular variance indicated higher genetic diversity (92%) within landraces than between (8%) different landraces. Population structure analysis showed that three subpopulations existed, and most of the South African accessions were restricted to one subpopulation, indicating that Bambara landraces has the ability to form unique haplotypes in different environments. Information harnessed in this study is helpful for further use in breeding programs for crop improvement. [ABSTRACT FROM AUTHOR]

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., (© 2012 Society of Chemical Industry.)

Little is known about the performance of South African cactus pear varieties in different agro-ecological regions. Effects of locality on internal quality parameters of available cactus pear varieties were examined. With only one exception, no significant differences among the mean replication values for the different parameters between the different locations were observed. The differences between mean values for most individual parameters at the three localities were highly significant. Highly significant differences between the mean values for the measured characteristics were observed, not only among the locations (except for the pulp glucose values), but also for the influences of genotype and interaction between locality and genotype. Significant variations existed between mean values of the different characteristics between localities. Genotype x environmental interactions were noted. It was concluded that Meyers is the most appropriate cultivar for economical purposes in South Africa.