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Maize (Zea mays L.) is an important crop in sub‐Sahara Africa for both human consumption and livestock feed. Maize use is often limited by ear‐rotting fungi, some of which produce deleterious secondary metabolites. The aim of this study was to determine the inheritance of resistance to Fusarium verticillioides as an indirect way of selecting for resistance to secondary metabolites such as the mycotoxin fumonisin that is produced by this fungus, under artificial inoculation and natural infection. Twelve inbred lines from Seed Co that were used as the females, were mated to 12 tester lines from the International Institute of Tropical Agriculture (IITA) that were used as males, using the North Carolina Design II. The resulting 144 F1 hybrids and six check hybrids were evaluated in Zimbabwe. Artificial inoculation with F. verticillioides was done at Rattray Arnold Research Station in the first season. The general (GCA) and specific combining ability (SCA) effects for F. verticillioides incidence were variable across sites for the lines and the testers. Six southern African inbred lines had desirable GCA for F. verticillioides ear rot and can be used as resistance sources. Outstanding testers from IITA that had negative GCA for F. verticillioides ear rot and fumonisins were identified. Both additive and nonadditive effects were implicated in resistance to ear rot caused by F. verticillioides and potential lines were identified that can be used in regional breeding programs. Core Ideas: Ear‐rotting fungi can produce secondary metabolites that cause diseases in humans and animals.Inheritance of resistance to Fusarium verticillioides and fumonisin was determined.Additive and nonadditive genetics effects were implicated in resistance to ear rot.Potential lines and testers were identified that can be used in regional breeding programs. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is the main staple cereal food crop cultivated in southern Africa. Interactions between grain yield and biochemical traits can be useful to plant breeders in making informed decisions on the traits to be considered in breeding programs for high grain yield and enhanced quality. The objectives of this study were to estimate the heritability of grain yield and its related traits, as well as quality traits, and determine the association between quality protein maize (QPM) with non-QPM crosses. Grain yield, and agronomic and quality trait data were obtained from 13 field trials in two countries, for two consecutive seasons. Significant genotypic and phenotypic correlations were recorded for grain yield with protein content (rG = 0.38; rP = 0.25), and tryptophan with oil content (rG = 0.58; rP = 0.25), and negative rG and rP correlations were found for protein with tryptophan content and grain yield with tryptophan content. Path analysis identified ear aspect, ears per plant, and starch as the major traits contributing to grain yield. It is recommended that ear aspect should be considered a key secondary trait in breeding for QPM hybrids. The negative association between grain yield and tryptophan, and between protein and tryptophan, will make it difficult to develop hybrids with high grain yield and high tryptophan content. Hence, it is recommended that gene pyramiding should be considered for these traits. [ABSTRACT FROM AUTHOR]

Background and objectives: Quality protein maize (QPM) nutritional quality involves high total protein content but reduced zein accumulation in maize endosperm, leading to increased non‐zein proteins, hence higher levels of essential amino acids such as lysine and tryptophan. The aim of this study was to assess the effect of low nitrogen (N) conditions in one location, and optimum conditions in three locations, on zein proteins in 10 QPM hybrids developed by the International Maize and Wheat Improvement Centre (CIMMYT) compared to two non‐QPM checks. Findings: With a few exceptions, total protein content, and γ‐ and α‐zein peak areas were significantly reduced under low N compared to optimal conditions, while β‐zein increased. Non‐QPM hybrids had higher protein content than QPM hybrids, and QPM hybrids had higher γ‐zein than non‐QPM in all environments. Higher α‐zein values than other zein types were observed in non‐QPM than in QPM genotypes in all environments. Significance and novelty: Low N significantly reduced protein content and all the zein fractions except for β‐zeins, which were increased. The advantages of a decrease in zein fractions in QPM under low N conditions were offset by a large decrease in grain protein content. [ABSTRACT FROM AUTHOR]

Grain legumes, including cowpea, are the cheapest sources of minerals and protein to enhance human nutrition. Cultivar development and deployment of cowpea with increased grain mineral content and protein composition rely on selection of genetically unique and complementary breeding lines. The objective of this study was to assess the grain minerals and protein composition of diverse cowpea collections of eastern, southern and western Africa to select promising parents to develop a breeding population. Twenty-two genetically diverse cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. The dried grain mineral contents were determined using an Atomic Absorption Spectrophotometre, while the protein content was determined by the combustion method. Analyses of variance showed significant (P < 0.05) effects of genotypes, locations and their interactions. The test genotypes showed considerable variation for the following nine mineral contents: calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varying from 0.07 to 0.12 mg kg−1; 4.46 to 7.81 mg kg−1; 0.06 to 0.11 g; 11.82 to 14.45 g; 1.86 to 2.27 g; 9.24 to 13.30 mg kg−1; 0.26 to 0.80 g; 4.63 to 5.92 g and 0.03.00 to 0.05 g, respectively. Further, the total protein content varied from 23.16 to 28.13%. Significant correlations were detected among some mineral elements and total protein content, suggesting the possibility of simultaneous selection for these traits. The principal component analysis (PCA) identified four principal components (PCs) contributing to 70.93% of the total explained variation amongst genotypes. Overall the following genotypes with desirable grain mineral and protein attributes were selected: IT90K-59 (Ca), 98K-5301 (Ca and protein), ITOOK-1060 (Cu), ITOOK-1217 and IT845-2246 (Fe), Bensogla (K, Na, and P), TVU11424 and ITOOK-1217 (Mg), CH14 (Mn and Na), TVU12637 (Mn) and Glenda and Vuli (Zn). The selected cowpea genotypes are useful genetic resources for population and cultivar development for grain nutrients composition. [ABSTRACT FROM AUTHOR]

Growing maize (Zea mays L.) hybrids tolerant to drought and low-nitrogen (N) stress would significantly reduce yield losses occurring in Africa. This study evaluated the performance of quality protein maize (QPM) F1 hybrids, and general (GCA) and specific combining ability (SCA) of QPM inbred lines for grain yield and other agronomic traits under stress and nonstress environments. A diallel cross of 15 QPM inbred lines was evaluated under drought and low-N stresses and optimal conditions in a total of 17 environments in Eastern and Southern Africa. Significant variations were observed among the hybrids for all measured traits. TZMI703 × (6207QB/6207QA), GQL5 × (6207QB/6207QA), and CML511 × (6207QB/6207QA) were identified as the best single crosses across environments. The GCA and SCA mean squares were significant for all measured traits, indicating that additive and nonadditive genetic effects were important in this set of genotypes under all test environments. The GCA effects were more important under drought stress, and SCA effects were more important under low-N and optimal conditions for grain yield. There was preponderance of GCA effects for most agronomic traits tested in all environmental conditions. Inbred lines CML159SR, GQL5, CML159, and CML312SRQ exhibited favorable GCA effects for grain yield under stress and optimal conditions, indicating that the genetic systems controlling a given trait under different conditions are at least partially similar. Cross combinations with favorable SCA effects for grain yield and other traits were also identified. Generally, this study provided evidence that good performance can be achieved under stress and nonstress conditions in QPM germplasm. [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. [ABSTRACT FROM AUTHOR]

Abstract: Quality protein maize (QPM) breeding involves the combined use of the opaque-2 (o2) gene and the genetic modifiers of the o2 locus to develop cultivars with modified kernel endosperm, and increased concentrations of lysine and tryptophan. This study was designed to assess grain yield performance, endosperm modification, and protein quality and quantity under two contrasting soil nitrogen environments. A 15-parent diallel cross was evaluated under one low nitrogen stress and one optimal nitrogen environment each at Harare (Zimbabwe) and Bako (Ethiopia). Most QPM hybrids showed higher protein quality levels than the best non-QPM check under both conditions. Protein concentration tended to vary across nitrogen levels, but not endosperm type. Significant differences were found for the test of main effect (nitrogen-level) for endosperm modification and tryptophan concentration. This indicated that QPM maintains quality even under low soil nitrogen, a widespread condition in Africa. General combining ability (GCA) mean squares were highly significant for most protein quality traits for each environment and across environments whereas specific combining ability (SCA) mean squares were not significant in most cases. This indicated that additive gene effects were primarily responsible for variation of most traits evaluated and hence progeny performance can adequately be predicted on the basis of parental performance. Inbred lines P2, P4 and P12 had desirable GCA effects for endosperm modification while P1 and P3 had the best GCA for tryptophan concentration in grain. The current study suggests that hybrids with desirable endosperm modification, protein quality and stable performance under low nitrogen stress and optimal conditions can be produced with careful selection. [Copyright &y& Elsevier]

Nineteen kenaf genotypes from Cuba, Taiwan, the USA, El Salvador, Guatemala, Russia, Spain and Indonesia, and three wild types collected in South Africa were analysed for genetic diversity using AFLP analysis. All could be uniquely distinguished from one another, but only a low level of genetic diversity was present. The most distinct accession, Guatemala 4, was 85% similar to all other accessions. The accessions clustered more or less according to known pedigree and/or origin. Two of the three wild types (Hibiscus cannabinus c and H. cannabinus a) clustered separately from the commercial and Russian accessions. One of the wild types, H. cannabinus b clustered with some of the commercial accessions. Commercial accessions in the first subgroup all originated from central and North America, and surrounding islands (Cuba and El Salvador). The Russian accessions are all grouped together. The second subgroup was the only group that contained accessions from different geographical origins. [ABSTRACT FROM AUTHOR]

Breeding for nitrogen use efficiency (NUE) is important to deal with food insecurity and its effect on grain quality, particularly protein. A total of 1679 hybrids were evaluated in 16 different trials for grain yield (GY), grain quality traits (protein, starch and oil content) and kernel weight (KW) under optimum and managed low soil nitrogen fields in Kiboko, Kenya, from 2011 to 2014. The objectives of our study were to understand (i) the effect of low soil N stress on GY and quality traits, (ii) the relationship between GY and quality traits under each soil management condition and (iii) the relationship of traits with low-N versus optimum conditions. From the results, we observed the negative effects of low N on GY, KW and the percentage of protein content, and a positive effect on the percentage of starch content. The correlation between GY and all quality traits was very weak under both soil N conditions. GY had a strong relationship with KW under both optimum and low soil N conditions. Protein and starch content was significantly negative under both optimum and low-N conditions. There was no clear relationship among quality traits under optimum and low N, except for oil content. Therefore, it seems feasible to simultaneously improve GY along with quality traits under both optimum and low-N conditions, except for oil content. However, the negative trend observed between GY (starch) and protein content suggests the need for the regular monitoring of protein and starch content to identify varieties that combine both high GY and acceptable quality. Finally, we recommend further research with a few tropical maize genotypes contrasting for NUE to understand the relationship between the change in grain quality and NUE under low-N conditions. [ABSTRACT FROM AUTHOR]

A field screening trial undertaken in Uganda showed that a number of Musa L. (Musaceae) cultivars and hybrids displayed high levels of resistance to banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), while most highland banana cultivars tended to be susceptible to weevil attack. In this study, research was undertaken to determine modalities of resistance to banana weevil. Laboratory studies suggested that all cultivars were attractive to the weevil and that females freely oviposited on all cultivars. While some differences were found between cultivars in attractivity and egg numbers, these were not related to subsequent damage. Therefore, antixenosis does not appear to play an important role in host-plant resistance to banana weevil. Larval survivorship rates in living corms were, for the most part, low on resistant cultivars, suggesting that antibiosis mechanisms offer the primary avenues of resistance. In the laboratory, development was slower on some resistant cultivars although survivorship rates on excised corm material were not as well related to levels of resistance as that on living material. Sap appeared to play a minor role in reducing egg eclosion rates on some resistant cultivars. Methanol extracts from Kayinja, a resistant cultivar, inhibited larval development on corms of susceptible cultivars in the laboratory. [ABSTRACT FROM AUTHOR]

Biofortified yellow-fleshed cassava is important in countries with high cassava consumption, to improve the vitamin A status of their populations. Yellow- and white-fleshed cassava were evaluated over three locations for proximate composition and cyanide content as well as retention of carotenoids after boiling. There was significant variation in the crude fiber, fat, protein and ash content of the genotypes. All but one of the yellow-fleshed cassava genotypes recorded higher protein values than the white-fleshed local genotypes across locations. The cyanide content of the genotypes varied between locations but was within the range of sweet cassava genotypes, but above the maximum acceptable recommended limit. Micronutrient retention is important in biofortified crops because a loss of micronutrients during processing and cooking reduces the nutritional value of biofortified foods. Total carotenoid content (TCC) ranged from 1.18–18.81 μg.g−1 and 1.01–13.36 μg.g−1 (fresh weight basis) for fresh and boiled cassava, respectively. All the yellow-fleshed cassava genotypes recorded higher TCC values in both the fresh and boiled state than the white-fleshed genotypes used as checks. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Summary A hybrid maize seed production technology has the potential to reduce the complexity of hybrid seed production and increase seed quality. Here, we investigate the potential impact of this technology on yields when hybrid maize is recycled. Hybrid maize recycling is a practice used by resource‐poor farmers as a coping mechanism during drought years. Recycling hybrid maize produced using this technology could provide a small yet significant yield benefit to resource‐poor farmers when they chose to recycle. This study provides an example of how social considerations can be incorporated into testing strategies of new technologies to ensure equitable benefits. Understanding the performance of new genetic technologies in farmers' real‐world realities, especially those relevant to resource‐poor farmers, is often overlooked but is essential to ensure equitable benefits. A new genetic technology was developed to simplify hybrid maize seed production in sub‐Saharan Africa, thereby improving farmers' access to high‐quality hybrid seed. Hybrids produced with this technology segregate 50:50 for pollen‐producing and non‐pollen producing and are designated 50% non‐pollen producing (FNP). FNP maize has higher yields in low‐input environments. As recycling hybrid maize seed remains a common practice in Zimbabwe, including among resource‐poor households, it is important to understand the impact of recycling FNP seed on the yield gains from the FNP technology. The potential impact of recycling FNP hybrid seed was assessed by testing three seed recycling scenarios on‐station and on‐farm. The extent of hybrid seed recycling and the types of households recycling hybrid maize seed over a 3‐year period were also investigated. Hybrid maize seed recycling was associated with resource‐poor farmers, although it was not continually practiced across years. Yield gains associated with FNP were retained under recycling practices, albeit reduced. The greatest yield benefit was when seed from only non‐pollen‐producing plants was used. Yield gains were associated with longer ears and more kernels per ear. While recycling hybrid maize seed reduces potential yields due to inbreeding depression, in the years when farmers cannot afford to plant hybrid maize only, recycling non‐pollen‐producing hybrid maize seed conferred a yield benefit of 116 kg ha−1. [ABSTRACT FROM AUTHOR]