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• Cucurbita maxima and C. moschata are leafy vegetables with numerous health benefits. • Drought stress tolerance screening can be achieved through potted seedlings for 10 and 20 days. • Biomass production, chlorophyll content, relative water content and membrane stability were not affected by stress after 10 days. • Stress exposure for 20 days resulted in compromised chloroplast biosynthesis, biomass production, membrane stability and increased proline content, albeit a good water status was maintained. • Phenotypic plasticities of the traits indicated which traits were reliable indicators of drought stress tolerance. A pot screening approach was used to identify mannitol stress tolerance indicating traits that were reliable and easy to determine, in two Cucurbita species. A population of C. maxima seedlings with trimmed roots were exposed to 0–800 mM mannitol for 20 days and the mannitol concentration required to inhibit root regrowth by 50±0.51% was established through a linear regression analysis (LD 50 = 453 mM, -1.11 MPa). The established LD 50 was then used to screen a population of C. moschata seedlings in addition to a second population of C. maxima. When exposed to 453 mM mannitol for 10 days, both species were able to regrow roots, maintain biomass production, chlorophyll content, high water status, membrane stability and accumulate proline as an osmoprotectant. Even with a good water status, stress exposure for 20 days compromised the biomass production, chlorophyll content, membrane stability and encouraged a surge in proline content. Based on their phenotypic plasticity indices, traits such as root regrowth, fresh weight, dry weight, relative chlorophyll content, electrolyte leakage and proline content were identified as potential indicators of stress tolerance at day 10 of mannitol stress. Meanwhile, root regrowth and proline content were the only traits identified as good indicators of stress tolerance at day 20 of mannitol stress. The biochemical, morphological and physiological traits of tested populations had varying degrees of plasticity under stress and this should be considered when screening and identifying drought resilient seedlings prior to labourious field tests. [ABSTRACT FROM AUTHOR]

Amaranthus spp occupies a strategic position in combating food and nutrition insecurity, as it is widely consumed in sub-Saharan Africa. It is drought tolerant and can grow on marginal soils, however, with adequate management; it can produce about 40 tons/ha of fresh leaves. The leaves are rich in nutrients that can combat malnutrition and support healthy eating. Despite the huge benefits offered by amaranth, it has been underutilized in South Africa. Its consumption is concentrated in rural areas, where it is harvested from the wild during the rains. There are no large-scale productions of amaranth, hence the lack of data on its production. Inadequate knowledge of its uses, agronomic requirement, low research efforts and the absence of an organized market are part of the reasons why amaranth is still underutilized in South Africa. This paper argues that with increased awareness of the benefits of amaranth and research geared towards agronomic improvement, social and economic acceptance, amaranth will be utilized nationwide with time. It recommends that conscious effort should be aimed at introducing amaranth into mainstream agricultural value chains through increased research attention and awareness of its nutritional benefits. This will ensure sustainable production to match the anticipated increase in consumption.

African leafy vegetables are rich in micronutrients that can help solve hidden hunger problems in Sub-Saharan Africa. However, their availability is limited due to seasonality and high post-harvest losses, which account for about 50%. In the field survey, we observed that wilted vegetables are usually discarded from the Morogoro Region, Tanzania markets. That loss also contributes to the loss of resources used to cultivate and transport the vegetables. Therefore, this study aimed to investigate the effect of the commonly used sun-drying method on the nutritional and sensory properties of fresh and wilted African nightshade and cowpea leaves. The common practice of handling fresh vegetables by vendors was adopted by putting the freshly harvested vegetables in an open basin at 24 ± 2°C for 3 days. Then, the stored vegetables were either sprayed or dipped in water to reduce the wilting rate. Next, the fresh and the wilted vegetables were dipped into hot water at 100°C for 7 min. Afterwards, the vegetables were sundried (22.5 ± 5.5°C) for three consecutive days. To study the effect of wilting, blanching, and sun drying fresh and dried vegetables were analysed for moisture, ascorbic acid, β-carotene, antioxidant activity and nitrate contents. Fresh and dried vegetables were used to prepare sauces using traditional recipes. The vegetable sauces were analysed for their sensory attributes using 30 semi-trained panellists. After drying, ascorbic acid contents, antioxidant activity and nitrate were reduced. The β-carotene significantly increased in the African nightshade and decreased in the cowpea leaves. Ascorbic acid ranged from 17.40 to 2.22 mg/100 g, antioxidant activity from 37.30 to 19.78, nitrate 230 to 10 mg/100 g and β-carotene from 96.38 to 79.49 mg/100. The sensory results showed relative acceptability among the sauces prepared from the fresh, fresh-dried and wilted-dried vegetables. In conclusion, blanching before drying reduced the water-soluble nutrient content but improved the sauces’ sensory scores of fresh and wilted vegetables. Therefore, reducing the post-harvest loss of African leafy vegetables is possible by drying the wilted vegetables and preparing the sauces with acceptable quality.

Amaranthus spp occupies a strategic position in combating food and nutrition insecurity, as it is widely consumed in sub-Saharan Africa. It is drought tolerant and can grow on marginal soils, however, with adequate management; it can produce about 40 tons/ha of fresh leaves. The leaves are rich in nutrients that can combat malnutrition and support healthy eating. Despite the huge benefits offered by amaranth, it has been underutilized in South Africa. Its consumption is concentrated in rural areas, where it is harvested from the wild during the rains. There are no large-scale productions of amaranth, hence the lack of data on its production. Inadequate knowledge of its uses, agronomic requirement, low research efforts and the absence of an organized market are part of the reasons why amaranth is still underutilized in South Africa. This paper argues that with increased awareness of the benefits of amaranth and research geared towards agronomic improvement, social and economic acceptance, amaranth will be utilized nationwide with time. It recommends that conscious effort should be aimed at introducing amaranth into mainstream agricultural value chains through increased research attention and awareness of its nutritional benefits. This will ensure sustainable production to match the anticipated increase in consumption. [ABSTRACT FROM AUTHOR]

Aim: Traditional African vegetables have high potential to contribute to healthy diets and climate resilience in sub‐Saharan African food systems. However, their genetic resources are likely at threat because they are underutilized and under the radar of agricultural research. This paper aims to contribute to a conservation agenda for traditional African vegetables by examining the geographical diversity and conservation status of these species. Location: Sub‐Saharan Africa. Methods: 126 traditional annual and perennial African vegetables were selected for their food and nutrition potential. Food uses and species' areas of origin were recorded from literature. Species' presence records were collected from open‐access databases of genebanks and herbaria. These records were used to determine geographical patterns of observed and modelled richness, to distinguish geographical clusters with different compositions of vegetables, to assess species' ex situ and in situ conservation status and to prioritize countries for conservation actions. Results: Of the 126 species, 79 originated in sub‐Saharan Africa. High levels of observed and modelled species richness were found in: (a) West Tropical Africa in Ghana, Togo and Benin; (b) West‐Central Tropical Africa in South Cameroon; (c) Northeast and East Tropical Africa in Ethiopia and Tanzania; and (d) Southern Africa in Eswatini. South Sudan, Angola and DR Congo are potential areas of high species richness that require further exploration. In general, ex situ conservation status of the selected species was poor compared to their in situ conservation status. Main conclusions: Areas of high species richness in West Tropical Africa, South Cameroon and Ethiopia coincide with centres of crop domestication and cultural diversity. Hotspots of diversity in Tanzania and Eswatini are especially rich in wild vegetables. Addressing the conservation of vegetable diversity in West Tropical Africa and South Cameroon is of most urgent concern as vegetable genetic resources from these locations are least represented in ex situ collections. [ABSTRACT FROM AUTHOR]

Production of high quality seeds in African leafy vegetables has not been practiced due to varying reasons including incorrect harvesting stages and fertilizer rates. Jute mallow (Corchorus olitorius L.) pods do not ripen simultaneously and fruits left to dry on mother plant long before harvesting, which face seed quality deterioration. Timely seed harvesting ensures maximum seed quality attributes of purity, germination and vigour. The present study aimed to investigate the effects of harvesting stages and nitrogen fertilizer on seed quality and yield of Jute mallow. Seed samples from four Jute mallow morphotypes (GEMS, GLMT, BEMS, and BLMT) were planted. Completely randomized block design was used for analysing the effects of nitrogen fertilizer levels (0, 60 and 120 kg/ha) with three replicates. Five plants were randomly tagged per plot and seed harvested at three maturity stages of green, tan and black. Seed quality test of purity, germination and vigour were done as per ISTA (2004) and means separation done by DMRT at p=0.05. Results showed that harvesting stage significantly influenced seed quality attributes, in a way that the maximum purity, germination and seed vigour was detected at tan pod stage and their lowest levels were observed at black pod stage. It can be concluded that best agronomic practices of Jute mallow seed can be attained when they harvested at tan stage together with use of N fertilizer for high seed quality and yield. [ABSTRACT FROM AUTHOR]

Indigenous leafy vegetables play a major role in strategies to attain food and nutritional security for African households. However, the potential of these vegetables in meeting the nutritional requirements have not been adequately exploited. This study assessed effects of shadenets on nutritive value of African indigenous leafy vegetables. The vegetables African nightshade (Solanum scabrum Mill.) and spiderplant (Cleome gynandra L.) and net covers colored white, gray, blue, and yellow, with unnetted plants as a control were used. From the 7th week after sowing (spiderplant) and transplanting (African nightshade) and at 2-week intervals nutritive quality variables were determined. Compared to open field, white net produced higher leaf β-carotene at 13 weeks after planting by 6% and 17% for African nightshade and spiderplant, respectively. Use of blue net cover reduced leaf vitamin C content by 94.5% and 79% in African nightshade and spiderplant, respectively, compared to open field at 15 weeks after planting. Higher leaf calcium was consistently recorded for plants grown under yellow net cover for African nightshade and white nets for spiderplant; but was reduced under blue net for both species on most sampling dates. Leaf iron content was maximized under yellow net cover for both crops. Use of net covers reduced leaf crude fiber content compared to open field; high leaf phenolic content was obtained in crops grown under white net for both vegetables. The crop responses were attributed to spectral quality, light intensity, and environmental changes to which the crops were subjected. The different colored agronet covers differentially influenced crop leaf nutritive quality. [ABSTRACT FROM AUTHOR]

Abstract African leafy vegetables (ALVs) play a crucial role in substituting the diets and household income of local people. Production of ALVs is, however, hampered by plant-parasitic nematodes, particularly Meloidogyne spp. The objectives of this study were: i) to determine the host suitability of 13 Amaranthus genotypes to Meloidogyne incognita and M. javanica in separate greenhouse experiments, and at three on-farm field sites, and ii) to verify resistance exhibited by genotype Thohoyandou, identified in greenhouse screenings, to the two said root-knot nematode species in micro plot studies. Glasshouse screenings for M. incognita showed reproduction factor (Rf) values < 1, indicating resistance, for genotypes Oyaya, Red Stem, Local 33 and Thohoyandou. Only genotypes Red Stem and Thohoyandou had Rf < 1 for M. javanica. Field data showed that genotypes Thohoyandou, Local 33, ACAT Seedfair and Oyaya maintained relatively low population densities of Meloidogyne spp. per 50 g roots at the three experimental sites, while A. cruentus, A. greacizans and A. tricolor , ex Botswana and Applebosch were the most susceptible. For micro plot experiments, values of all reproduction parameters were significantly lower for final population densities of resistant genotype Thohoyandou compared to that of susceptible genotype Arusha when evaluated against M. incognita. For M. javanica, only egg-mass numbers per root system were significantly lower for genotype Thohoyandou compared to those of Arusha. Use of resistant genotype Thohoyandou will benefit producers and can contribute to food security, household income and sustainable crop production. Highlights • Smallholding farmers has limited knowledge with regard to plant-parasitic nematodes. • Damage caused by nematodes usually goes unnoticed or associated with other growth-limiting factors by producers. • Nematode damage may leads to increased aerial growth as the plants try to compensate. [ABSTRACT FROM AUTHOR]

There is a decline in the production, utilization and diversity of underutilized crops including African Leafy Vegetables (ALVs), which poses a threat to the status of food security and rural development. This study examines the factors influencing households’ participation decision in the production of African leafy vegetables in the Limpopo Province of South Africa using a double-hurdle model that accounts for whether or not smallholder farmers produce ALVs (decision to participate) and how much land was allocated for ALV production (level of participation). Participation and level of participation decisions were analysed using cross section data collected from 126 smallholder farmers in 2013. The empirical results suggest that factors explaining participation decision and the level of participation are different. Hence, it is imperative that policies that are aimed at incentivising participation and level of participation and their impacts on food security and nutrition target different groups. The commercialization of ALVs could also promote rural development in the study area. [ABSTRACT FROM AUTHOR]

The major challenge affecting rural resource-poor households (RRPHs) in South Africa is deficiencies in micronutrients (iron and zinc) and vitamin A. Traditional leafy vegetables (TLVs) are dense in iron, zinc, and β-carotene concentrations. Therefore, they are deemed suitable to improve the dietary diversity of RRPHs. The main objective of this study was to assess the effect of irrigation regimes on nutritional water productivity (NWP) of selected leafy vegetables [ Amaranthus cruentus (Amaranth) and Cleome gynandra (Spider flower), both TLVs, and Beta vulgaris (Swiss chard)]. Experiments were conducted under a rain shelter at the ARC-VOP, Pretoria, South Africa, during two consecutive seasons (2013/14 and 2014/15). Leafy vegetables were subjected to three irrigation regimes [well-watered (I 30 ), moderate water stress (I 50 ), and severe water stress (I 80 )]. Data collected [(aboveground biomass (AGB), aboveground edible biomass (AGEB), actual evapotranspiration, and nutrient concentrations (iron, zinc and β-carotene)] were used to calculate NWP of leafy vegetables. Swiss chard exhibited a higher portion of AGEB compared to TLVs due to its larger harvest index (0.57-0.92). Selected TLVs displayed superiority in terms of nutrient richness compared to Swiss chard, under I 50 . Results indicated that TLVs could provide more than the daily-recommended nutrient intake (DRNI) for vitamin A to all age groups. For iron, Spider flower could supply more than the DRNI to infants between 1 and 3 years of age, whereas for zinc, it could supply approximately 11% to this age group. However, higher micronutrient and β-carotene concentrations did not translate to superior nutritional yield (NY). Swiss chard showed higher Fe-NY and Zn-NY, whereas TLVs were rich in β-carotene-NY. Similarly, Swiss chard demonstrated the highest Fe-NWP (1090 mg m −3 ) and Zn-NWP (125 mg m −3 ), whereas Amaranth was larger in β-carotene-NWP (1799 mg m −3 ), under moderate water stress. These results show that there may be an opportunity to improve NWP under drought conditions. There is a need for future studies that will assess NWP for a wider range of leafy vegetables. These studies should be conducted in different locations and explore the effect of management factors (fertiliser, water stress, planting density and planting date), and soil type on NWP of micronutrients and β-carotene. [ABSTRACT FROM AUTHOR]

Abstract The aims and objectives of the current study were to investigate the level of genotypic variation in the leaf calcium (Ca) and iron (Fe) contents within a relatively small population of Solanum nigrum , to select high and low Ca- and Fe-producing genotypes and clonally propagate them in vitro and to test the resulting clonal progeny ex vitro for their Ca and Fe content and growth, based on their physiological age and on the use of different substrates. Firstly, chilled and fresh S. nigrum seeds were acid-scarified and sown onto potting soil in a greenhouse. Optimal germination (95%) was achieved in seeds chilled for 3 weeks and scarified with 0.01 M HCl for 10 min. Thereafter, fifty 6-week old seedlings were screened using Inductively Coupled Plasma-Optical Emission Spectrometry resulting in ranges of leaf calcium (Ca) and iron (Fe) of 331.0–916.3 mg 100 g− 1 dry mass (DM) and 0.64–14.95 mg 100 g− 1 DM, respectively. When a micropropagation protocol using seedling nodal and leaf explants was investigated, direct organogenesis using leaves on shoot multiplication medium containing 3 mg l− 1 benzylaminopurine (BAP) and rooting on hormone-free MS medium was most successful resulting in 80% explants producing shoots, 50 shoots/explant and 80% rooted shoots. After acclimatisation in nutrient-rich potting soil, the yield was 25 plants/explant. Subsequently, genotypes for high Ca (G20), high Fe (G15), low Ca (G43) and low Fe (G35) were micropropagated using the established protocol. At certain physiological ages, G43 was the only genotype whose clones had better shoot and root growth on the nutrient-poor substrate than on the nutrient-rich one while G35 was the only genotype whose clones had better root growth on the nutrient-rich substrate than on the nutrient-poor one. The clones of G20 produced high numbers of leaves and shoot and root fresh and dry masses on both substrate types but the overall growth was better on soil. For the G15 clones, shoot and root growth increased with age with no overall difference in growth between the substrates. The levels of phenotypic plasticity for the selected genotypes were found to be G43 > G35 > G20 > G15 and in cases where phenotypic plasticity was observed, more clones with higher overall biomass were found on the nutrient-poor substrate. When compared to their respective parents, the G20 clones produced the same amount of Ca on both tested substrates while G43 exhibited higher Ca production on the nutrient-rich substrate. The Fe levels in the clones of G15 decreased with physiological age, and were lower than that of the parent plant, on both the nutrient-rich and poor substrates while the Fe levels of the G35 clones were higher than that of the parent plant on nutrient-rich soil at all ages. Highlights • Genotypic variation exists in leaf Ca/Fe content in a population of Solanum nigrum. • Leaf explants were more effective than nodal explants for clonal propagation. • Selected genotypes had different levels of phenotypic plasticity for ex vitro growth. • Ca content in clones does not change with age and is not affected by substrate. • In general, Fe content in clones decrease with age and is not affected by substrate. [ABSTRACT FROM AUTHOR]

Cleome gynandra is one of the most promising African leafy vegetables consumed in most parts of Africa. The crop is a rich source of vitamins A and C and minerals such as calcium, iron, magnesium and protein. The leaves and seeds of spider plant are used in indigenous medicine in several countries. Despite the numerous nutritive benefits and ethnopharmacological uses of the plant, C. gynandra is still underutilized due to lack of awareness and promotion of production technologies and utilization. Available information is limited and short on several relevant and rudimentary components. Hence, this review focuses on the current knowledge on C. gynandra, with regards to its botany, ecology, cultivation systems, utilization, nutraceutical properties as well as the breeding avenues that will contribute to promoting the species, aimed at ensuring food and nutritional security and efficient management of its genetic resources. Breeding programmes aimed at minimizing the bitterness of the leaves so to arouse the interest of consumers, and the mechanisms involved in the responses and adaptation of C. gynandra as a C4 plant to salinity stress, were also explored. [ABSTRACT FROM AUTHOR]

Spider plant ( Cleome gynandra L.) is one of the most important and highly prioritised African leafy vegetables consumed in many parts of Africa due to its rich source of vitamins A and C and minerals such as calcium, iron, magnesium and protein. In order to improve upon yield and promote the breeding of improved cultivars, this study was carried out to understand variation in morpho-agronomic characters of twenty-four accessions of Cleome gynandra in Ghana. The accessions were evaluated for morpho-agronomic traits using Completely Randomized Design (CRD) with three replications. There were variations among the accessions in terms of growth habit, stem pubescence, stem colour, flower colour and petiole colour. Significant differences (p < 0.05) were recorded among the accessions for plant height, petiole length, number of seeds per pod and 100 seed weight. Hierarchical cluster analysis based on the morpho-agronomic traits grouped the accessions into four distinct clusters suggesting diversity among the accessions. Correlation values among the agro-morphological characters revealed that some of the traits were associated with each other. Nevertheless, the extent of correlation values differed from one trait pair to the other. Accessions KNUST001, KNUST005, KNUST006, KNUST011 and KNUST020 recorded higher values in terms of number of leaflets per compound leaf accompanied with higher leaf length values. Desirable genotypes among the accessions identified could be used in developing improved varieties to reap the full potential benefits of this important indigenous leafy vegetable. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: The younger generation of South Africans generally do not consume traditional meals prepared using African green leafy vegetables, primarily because they are regarded as bitter, “poverty” foods. Canning of these vegetables could create value‐added products that can be sold in the commercial market. Descriptive sensory evaluation and consumer acceptance testing with young females were used to assess the potential of such products. RESULTS: The sensory attributes of amaranth, cleome and cowpea leaves canned in brine and in a cream sauce were described using 21 attributes grouped by aroma, taste, texture/mouthfeel and aftertaste. Amaranth and Swiss chard products were described as sweet with a popcorn‐like aroma. Cleome products were described as bitter, sour, pungent, chemical‐tasting, astringent, sandy with a metallic mouthfeel and strong aftertaste. Cowpea products were described as having woody and tobacco aromas as well as a chewy and cohesive texture. Among the products canned with a cream sauce, young female consumers preferred amaranth and Swiss chard; cowpea was less liked, while cleome was least liked. CONCLUSIONS: Canned amaranth leaves have potential as a commercial product that may be well liked by young consumers. The cowpea leaves product has consumer potential, but the formulation needs revision, while canned cleome leaves need further research work. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim of this study has been to analyse the value chain of African leafy vegetables in the Limpopo Province of South Africa. This was done by identifying the prominent value chain actors, institutions governing the chain, the infrastructural endowments, key factors and challenges affecting the success or failure of the value chains for African leafy vegetables. Relationships among the value chain actors were weak, with transactions based mostly on spot markets. While smallholder farmers attain high gross margins, their intention to take part in the mainstream markets are prevented by lack of technical advice on production, lack of packaging and processing services, poor infrastructure, deficiency of contractual agreements between actors, and lack of access to finance. Although producers currently attain relatively higher gross margins, more benefits might be realized if government services (such as training, seed production and distribution) could either be decentralized or privatized. Future policy interventions should focus on promoting value addition along the African leafy vegetable chain, provision of cold storage facilities by municipalities closer to smallholder farmers in the rural areas and this will stabilize farm gate prices to encourage continuation of production.

Fertility management techniques being promoted in sub-Saharan Africa (SSA) seek to grow indigenous vegetables economically and sustainably. This study was conducted in a phytotron chamber and compared yield, soil carbon (C) speciation and greenhouse gas (nitrous oxide (N2O) and carbon dioxide (CO2)) emissions from SSA soils of two ecoregions; the dry savanna (lna, Republic of Benin) and rainforest (Ife, Nigeria) cultivated with local amaranth (Amaranthus cruentus) under manure (5 t/ha) and/or urea (80 kg N/ha) fertilization. Vegetable yield ranged from 4331 kg/ha to 7900 kg/ha in the rainforest, RF, soils and 3165 kg/ha to 4821 kg/ha in the dry savanna, DS, soils. Yield in the urea treatment was slightly higher compared to the manure, and manure+urea treatment, but the difference was not statistically significant. Cumulative CO2 emissions over 21 days ranged from 497.06 to 579.47 g CO2-C/kg soil/day in the RF, and 322.96 to 624.97 g CO2-C/kg soil/day in the DS, while cumulative N2O emissions ranged from 60.53 to 220.86 mg N2O-N/kg soil/day in the RF, and 24.78 to 99.08 mg N2O-N/kg soil/day in the DS. In the RF samples, when compared to the use of urea alone, the combined use of manure and urea reduced N2O emissions but led to an increase in the DS samples. ATR-FTIR analysis showed that the combined use of manure and manure+urea increased the rate of microbial decomposition in the soils of the DS, but no such effect was observed in soils of the RF. We conclude that combining manure and urea fertilization has different effects on soils of the two ecoregions, and that RF farmers can reduce agricultural N2O emissions without compromising soil productivity and yield potential.

This study investigated the speciation, transformation, and availability of P during indigenous vegetable production by employing a combination of chemical and spectroscopic techniques. The study focused on sites in two ecozones of SSA, the dry savanna (lna, Republic of Benin) and rainforest (Ilesha, Nigeria). Both sites were cultivated with two indigenous vegetable species: local amaranth (Amaranthus cruentus (AC)) and African eggplant (Solanum macrocarpon (SM)). The soils were treated with 5 t/ha poultry manure and urea fertilizer at the rates of 0, 20, 40, 60, and 80 kg N/ha. Soil samples were collected before planting and after harvest. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy was used to determine P speciation in these soils. Quantitative analysis showed that adsorbed and organic P were the two dominant P species in the manure amended dry savanna (DS) soils before planting and after harvest in soils cultivated with both AC and SM, with the addition of urea (40 kg N/ha) causing an increase in the organic P form in dry savanna soils cultivated with AC. Soils of the rainforest (RF) cultivated with AC initially had large amounts of apatite P in the manure amended soils prior to planting, which was transformed to adsorbed and organic P after harvest. Urea addition to the rainforest soils shifted the dominant P species from organic P to adsorbed and apatite P, which was likely to limit P availability. Soils cultivated with SM had similar proportions of both organic and adsorbed P forms, with 40 kg N/ha addition slightly increasing the proportion of adsorbed P.

Over the last decade, African indigenous leafy vegetables (AIVs) such as African nightshade ( Solanum scabrum Mill.) have featured increasingly in both formal and informal markets in the peri-urban and urban centres of Africa, due to the increasing awareness of their nutritive and medicinal as well as expanding economic value. AIVs are rich in nutritional and health promoting plant compounds such as vitamins, minerals, proteins, dietary fibre and antioxidant compounds. However, the crop is highly perishable and more than half of it is lost before it reaches the consumer. In Kenya, appropriate postharvest handling and treatments, storage or refrigeration facilities are lacking. More so, the information on postharvest losses of the AIVs is limited, making the management of such losses along the supply chain very difficult. The objective of the study was to determine nutritional and economic losses of African nightshade plants along the supply chain, i.e. from producer until marketing. The study was conducted in the three main commercial AIVs producing counties in Kenya, i.e. Nakuru, Kisii and Kakamega, where three farmers from each county were randomly selected. The farmers were allowed to carry out their normal routine AIVs handling procedure right from harvesting to selling; and samples were collected at each supply chain stage (at harvest, before transport, after transport and at the market). Dry matter, selected macro-nutrients (N, P, K, Ca and Mg) and micro-nutrients (Fe and Zn), protein, carotenoids and chlorophyll content, cumulative produce and economic losses as well as the causes of losses were evaluated. The results obtained revealed significant quantitative, nutritive, and economic losses of African nightshade along the supply chain. The dry matter content was reduced by between 32.8–45.5%, depending on the county, along the supply chain. The mineral elements and protein were reduced by between 3.2–29.4%, while chlorophylls and carotenoids were reduced by between 70.9–90.9% and 70.4–91.9%, respectively. Cumulative produce loss was between 71.8–292.4% while the economic loss was between 12.6–34.4%. The findings indicate the immense losses of nutritional, quantitative and economic values of African nightshade along the supply chain. Lack of certified seed varieties, unfavourable weather, inadequate postharvest handling practices and technologies as well as insect pest and diseases are the main causes of losses during the supply chain. Therefore, maintaining quality attributes and managing postharvest losses in AIVs could be among the key issues to improving food security in developing countries. [ABSTRACT FROM AUTHOR]

Currently, consumer eating habits have shifted to an increasing demand for high quality, safe and healthy food products worldwide. In many African countries, specifically African indigenous leafy vegetables (AIVs) gained importance in this respect contributing to human diet by providing minerals, proteins, vitamins and health-promoting antioxidant compounds. Moreover, these vegetables have an immense potential in creating job opportunities in rural as well as peri-urban areas. However, AIVs tend to suffer severe quantitative and qualitative postharvest losses because of their high perishability. UV-C has been mainly applied in sanitation and food safety for its germicidal effect but also has an impact on preventing nutritional losses. To address this, studies were conducted to evaluate the effect of postharvest application of hormic UV-C dosages on bioactive plant compounds of two AIVs, i.e. African nightshade ( Solanum scabrum Mill.) cv. Olevolosi and vegetable amaranth ( Amaranthus cruentus L.) cv. Madiira. Eight weeks after planting, the leaves were harvested and treated with UV-C (254 nm) at either 1.7 kJ m −2 or 3.4 kJ m −2 while untreated leaves served as control. The leaves were kept for 4 and 14 d at 20 °C (65% RH) and 5 °C (85% RH), respectively. The quality parameters studied were fresh weight loss, mineral elements (N, P, K, Ca, Mg, Fe, and Zn), protein, and structural carbohydrates determining dietary fibre content and microbial counts. In addition, antioxidative, health promoting plant compounds, i.e. carotenoid, and chlorophyll contents were evaluated. The results showed that fresh weight loss of both AIVs was significantly reduced with application of lower UV-C dosage (1.7 kJ m −2 ). Mineral elements and proteins were variedly affected with a general decline in the initial stages followed by an increase compared to the untreated leaves. Hemicellulose and cellulose was significantly increased in vegetable amaranth and lignin content was significantly increased in African nightshade following UV-C treatment. Chlorophyll and carotenoid contents declined within 2–4 d during storage, depending on storage conditions; but thereafter increased again significantly compared to the control. Aerobic mesophyllic and yeast counts were significantly reduced by UV-C treatment, while mould counts were not affected. The findings demonstrate the potential of using hormic UV-C for maintaining the nutritional quality of AIVs during their supply chain as an easy to apply and effective tool, hence contributing to improved food accessibility and food safety in Sub-Saharan areas such as Kenya. [ABSTRACT FROM AUTHOR]

Production of indigenous African leafy vegetables such as African nightshade (Solanum scabrum Mill.), whose high nutritional and medicinal value is well documented is still limited due to insufficient preharvest techniques. Electric current is known to improve quality in food crops. Therefore, in the present study, the effects of direct-electric-current (DC) on growth and characteristic bioactive and health promoting compounds were evaluated in different morphological sections, i.e., leaves and stems of African nightshade cv. Olevolosi. Six weeks old plants were exposed to different DC applied with a voltage of 8 and 16 V, 10 h/day for 12 days. Non-treated plants served as control. Plant growth, primary and secondary plant compounds were evaluated. Applying DC increased leaf fresh (11.5-14.4%) and dry (12.1-24.2%) weight as well as marketable leaves (29.1-55.3%). Biosynthesis of chlorophylls and carotenoids was enhanced by increased DC. Furthermore, dietary fibre fractions such as hemicellulose was promoted (23.3-45.3%) by DC applications, while cellulose and lignin remained unaffected. Minerals accumulated with increasing DC. Alteration of cell membrane permeability due to DC may enhance physiological processes leading to the improved growth and acceleration of bioactive compounds in African nightshade leaves.

The reuse of greywater, wastewater from sources other than toilets, could enable low-income households to save potable water for drinking and cooking. Greywater irrigation of food crops is widely practised but its effects on African leafy vegetables (ALVs), which hold potential for cultivation to improve food security, are unknown. This study investigated the effects of synthetic greywater irrigation on germination in three ALVs, viz., Amaranthus dubius, Cleome gynandra and Solanum nigrum, and subsequent seedling growth in A. dubius and S. nigrum. Seeds and seedlings were treated with chlorinated and dechlorinated greywater and tap water, supplemented with nutrients. Greywater application decreased germination capacity (by 23-25%) when assessed in Petri dishes in A. dubius only. However, greywater application was less harmful to A. dubius seeds sown in soil. Vigour was compromised in greywater-treated seeds of all three species but greywater can be used to irrigate freshly-sown seeds of A. dubius without reducing percentage seedling production. However, greywater irrigation reduced capacity (by 21-23%) and rate of shoot emergence in S. nigrum, and growth and chlorophyll content in both species. These negative effects were accompanied by increased soil electrical conductivity (after 21 d) and pH (after 14 d). The reduced growth under greywater irrigation was most likely based on a reduction in light-harvesting capacity and/or nutrient availability. Overall, S. nigrum seedlings were significantly more sensitive to the negative effects of greywater, possibly due to increased transpirational water loss under greywater irrigation. The effects of greywater were largely independent of chlorine content. Applying greywater in excess of plant requirements and/or alternating greywater irrigation events with freshwater watering events could promote leaching of salts found in greywater. The effects of greywater irrigation on soil water and nutrient availability demand further investigation for ALVs. [ABSTRACT FROM AUTHOR]

Objective: A randomized controlled trial was conducted to assess the effect of African leafy vegetable (ALV) consumption on Fe, Zn and vitamin A status in children.Design: Children were randomly allocated to receive either a 300 g cooked ALV dish and school meal starch (n 86) or the normal school meal (n 81) five times per week for three months. ALV in the dish consisted mainly of Amaranthus cruentus (at least 80 %) and the remainder of Cleome gynandra, Cucurbita maxima or Vigna unguiculata. Nutrient content and consumer acceptance of the ALV dish were also determined.Setting: North West Province, South Africa.Subjects: Grade R to grade 4 children (6-12 years old) of two farm schools.Results: The ALV dish contributed 11·6-15·8 mg Fe and 1·4-3·7 mg Zn. At baseline, prevalence of deficiencies in the intervention group was 16·0 %, 16·3 %, 7·0 % and 75·6 %, respectively, for anaemia (Hb<11·5 g/dl), Fe (serum ferritin<15 µg/l), vitamin A (serum retinol<20 μg/dl) and Zn (serum Zn<65 μg/dl); and in the control group 10·5 %, 18·5 %, 2·5 % and 75·3 %, respectively. No significant estimated intervention effect was found.Conclusions: This randomized controlled trial showed that ALV were unable to improve serum retinol, serum ferritin or Hb if there are only mild deficiencies present. Furthermore, despite the low Zn status in the study population, ALV consumption did not improve serum Zn concentrations either. [ABSTRACT FROM AUTHOR]

Using laboratory incubation, the response of seed germination and emergence to variability in temperature and light was examined for spider flower ( Cleome gynandra L.), amaranth ( Amaranthus cruentus L.), non-heading Chinese cabbage ( Brassica rapa L. subsp. chinensis ), nightshade ( Solanum retroflexum Dun.), pumpkin ( Cucurbita maxima Duchesne), tsamma melon ( Citrullus lanatus Thunb.), Jew's mallow ( Corchorus olitorius L.) and cowpea ( Vigna unguiculata (L.) Walp.). Effect of temperature on seed germination and emergence was monitored under continuous darkness and at constant temperatures that ranged from 4 °C to 44 °C with 4 °C increments. The effect of light on seed germination was measured at 25 °C. Temperature affected germination rate and final germination percentage of all species tested in ways that were characteristic for each of the species tested. Generally, optimum germination occurred at temperatures ranging between 29 °C and 32 °C but at higher temperatures for V. unguiculata (36 °C) and C. olitorius (35 °C). The minimum temperature for germination ranged between 8 °C and 15 °C, and the maximum between 36 °C and 44 °C. Optimum temperatures for seedling emergence ranged from 25 °C to 31 °C, the maximum between 32 °C and 40 °C and minimum between 2 °C and 13 °C. Light positively ( p < 0.01) affected onset of germination in A. cruentus , B. rapa subsp. chinensis and C. olitorius , and final germination percentage of B. rapa subsp. chinensis , C. lanatus and S. retroflexum . The results suggested that under South African conditions, seeds of the eight species will typically germinate optimally as temperatures rise during spring before the occurrence of very hot temperatures in summer. Due to their positive response to light, germination of B. rapa subsp. chinensis , C. lanatus and S. retroflexum seeds is expected to be optimal when sown at or close to the soil surface. [ABSTRACT FROM AUTHOR]

This study surveyed urban consumers in Eldoret Town, Kenya to determine the willingness to pay ( WTP) a premium for African leafy vegetables (ALVs) and the underlying determinants using the semi-double bounded contingent valuation choice and logit models, respectively. Consumers generally preferred ALVs to exotic leafy vegetables and were willing to pay an average premium of 79 % for them: 88 % and 70 % in open air and supermarkets, respectively. The WTP premium was positively influenced by age, presence of children in the household, years of schooling of the household decision maker and the number of years the consumers had been consuming ALVs. Implications for policy are drawn. [ABSTRACT FROM AUTHOR]

Background: The dietary shift from indigenous and traditional plants (ITPs) to cash crops and exotic plant food sources increases the risk of malnutrition and other nutrition-related non-communicable diseases, especially in poor rural communities. Farm communities in South Africa have been associated with poor nutritional status and extreme poverty. ITPs have been found to be affordable sources of several micronutrients. However, knowledge of and the use of these plants are declining, and little is known about the child's acceptance of dishes prepared with ITPs. This knowledge can be used to improve the general acceptance of ITPs. This study aimed to gain insight into parents' knowledge and perceptions and their use of ITPs in a farming community in the North West Province and to assess children's acceptance of and preference for dishes made with African leafy vegetables (ALVs) and Swiss chard. Methods: Parents (n = 29) responsible for food preparation for children in grade 2 to 4 in two schools were purposively selected for four focus group discussions. A sensory evaluation assessed the children's (n = 98) acceptance of, preference for and intended consumption of dishes made with leafy vegetables. The dishes were made of Amaranthus spp., Cleome gynandra, Cucurbita maxima, Vigna unguiculata and Beta vulgaris. Results: Parents mentioned 30 edible ITPs during the focus group discussions. Parents had knowledge of available ITPs and their use as food. Location, seasonal variation and rainfall affected the availability of and access to ITPs. Sun-dried ITPs were stored in sacks for later use. ITPs were perceived as healthy, affordable and delicious, hence acceptable to the parents. The children also evaluated the dishes made with ALVs as acceptable in terms of colour, smell and taste. Swiss chard was preferred, most likely because of the children's exposure to this vegetable. Children indicated that they would like to eat these leafy vegetables twice a week. Conclusion: These results look promising for the promotion of ITPs as a strategy to reduce malnutrition in rural farm communities and for potential inclusion of these micronutrient-rich ALVs in school feeding programmes to improve the nutritional status of children. [ABSTRACT FROM AUTHOR]

Abstract: Crop responses to different manures differs considerably, however, the factors responsible for it have not been conclusively elucidated. Consequently, this study examined the biomass response of Cucurbita maxima and Solanum retroflexum to application rates of chicken and kraal manures of cattle and goat, and soil factors related to salinity. The crops’ biomass yield increased linearly with increase in application rates of kraal and chicken manures, but steeper in the latter. Results showed that significant decline in biomass yield in chicken manure at rates above 8.5tonsha−1 were not due to salinity. The crops’ response to cattle and goat kraal manures was linear but polynomial (cubic) in layer chicken manure. It was concluded that the yield decline in chicken manure was due to other manure factors except salinity, probably toxicity effect of the manure fatty acids. Further research was however, recommended to elucidate this claim. [Copyright &y& Elsevier]

Objectives: The objectives of this study were to determine the availability of, access to and nutrition-related uses of African leafy vegetables in rural and urban households; and to determine the β-carotene content of the dominant African leafy vegetable. Design: The study consisted of a qualitative explorative phase (field walks, semi-structured interviews with key informants, focus group discussions) at two rural sites; and a quantitative household survey (questionnaire) at two rural and one urban site. Amaranth leaves were analysed for β-carotene content. Setting and subjects: The household survey included households at a rural site in Limpopo province (n = 100); and a rural (n = 101) and urban (n = 391) site in KwaZulu-Natal province, South Africa. Results: A variety of edible plants were identified during field walks at the two rural sites. Focus group discussions narrowed this down to ten plants at the rural Limpopo site and six at the rural KwaZulu-Natal site. The most popular leaves were amaranth (Amaranthus spp), spider plant (Cleome gynandra), wild watermelon (Citrullus lanatus) and blackjack (Bidens spinosa), consumed individually or mixed with other leaves. Rural households procured leaves mostly from the wild whereas urban households relied more on informal markets. In Limpopo, leaves were dried and stored for consumption during winter. KwaZulu-Natal households considered African leafy vegetables food for the poor. Leaves were boiled in salted water, or steamed and then fried in oil. Fried and boiled amaranth leaves contained 627 and 429 μg retinol activity equivalents/100 g respectively. Conclusions: Availability of, access to and nutrition-related uses of African leafy vegetables are context-specific, with inter- and intraprovincial rural/urban differences. Information collected during small studies within a specific area can therefore not be generalised for the overall South-African population. Amaranth can potentially contribute significantly to vitamin A requirements of nutritionally vulnerable communities. [ABSTRACT FROM AUTHOR]

Despite the increased recognition of African Leafy Vegetables (ALVs) as important source of vitamin A, there is still paucity of research highlighting on the vitamin A intake attributed to them. The level and the extent of contribution of ALVs could inform programming, monitoring and evaluation of vitamin A-related nutrition and development programs. The study aimed at investigating the level of contribution of ALVs to household vitamin A intake and the influence of household monthly income in a rural setting, through use of selected data from a cross-sectional vitamin A consumption survey in Butere-Mumias District, western Kenya. A multistage cluster sampling procedure was used to select 814 households considered for the survey. It was found that plant sources contributed about 43.1% of total household vitamin A intake. ALVs contributed 65.7% of vitamin A from plant sources and 32.7 % of household vitamin A intake. Predominant ALV was the cowpea leaves which accounted for about 45% of vitamin A contributed by ALVs, 34% of the contribution of plant sources and 14.7% of household vitamin A intake. Although the influence of monthly income on the level of vitamin A from ALVs was not conclusive, there were some indications that lower intake from ALVs was positively correlated with lower incomes and vice versa. Income was weakly and negatively associated with household vitamin A intake (r=-1.92, 3.7% of variance explained), and the opposite was true for the proportion of income spent on food verses household vitamin A intake (r=1.64, 2.7% of variance explained). It was apparent that ALVs formed an important dietary source of vitamin A in rural households in western Kenya with cowpea leaves as a predominant contributor. In areas of similar environmental conditions, ALVs production, marketing and consumption should be promoted. There was no evidence that increase in income among the rural folk may likely improve ALVs consumption and vitamin A intake. It is thus recommended that development programs and policies consider ALVs as significant source of vitamin A, and that increments in incomes per se may not significantly influence household vitamin A intake and from ALVs. [ABSTRACT FROM AUTHOR]

Abstract: In this report, we present preliminary nutritional data for traditional leafy vegetables collected in Kwa Zulu-Natal, South Africa, including their content of mineral elements (Ca, P, Na, Zn, Mg, Mn and Fe) and antioxidant levels. Twenty vegetables were studied: Amaranthus dubius, Amaranthus hybridus, Amaranthus spinosus, Asystasia gangetica, Bidens pilosa, Centella asiatica, Ceratotheca triloba, Chenopodium album, Cleome monophylla, Cucumis metuliferus, Emex australis, Galinsoga parviflora, Justicia flava, Momordica balsamina, Oxygonum sinuatum, Physalis viscosa, Portulaca oleracea, Senna occidentalis, Solanum nodiflorum and Wahlenbergia undulata. The results of this study provide evidence that these local traditional vegetables, which do not require formal cultivation, could be important contributors to improving the nutritional content of rural and urban people. From this study, it was determined that twelve leafy vegetables, namely A. dubius, A. gangetica, A. hybridus, A. spinosus, C. metuliferus, C. monophylla, C. triloba, G. parviflora, J. flava, M. balsamina, P. viscosa and W. undulata provide mineral concentrations exceeding 1% of plant dry weight and are much higher than typical mineral concentrations in conventional edible leafy vegetables; they are thus recommended for future commercial cultivation. High levels of antioxidant activity (96%) were noticed in J. flava and P. oleraceae. [Copyright &y& Elsevier]

Fertility management techniques being promoted in sub-Saharan Africa (SSA) seek to grow indigenous vegetables economically and sustainably. This study was conducted in a phytotron chamber and compared yield, soil carbon (C) speciation and greenhouse gas (nitrous oxide (N2O) and carbon dioxide (CO2)) emissions from SSA soils of two ecoregions; the dry savanna (lna, Republic of Benin) and rainforest (Ife, Nigeria) cultivated with local amaranth (Amaranthus cruentus) under manure (5 t/ha) and/or urea (80 kg N/ha) fertilization. Vegetable yield ranged from 4331 kg/ha to 7900 kg/ha in the rainforest, RF, soils and 3165 kg/ha to 4821 kg/ha in the dry savanna, DS, soils. Yield in the urea treatment was slightly higher compared to the manure, and manure+urea treatment, but the difference was not statistically significant. Cumulative CO2 emissions over 21 days ranged from 497.06 to 579.47 g CO2-C/kg soil/day in the RF, and 322.96 to 624.97 g CO2-C/kg soil/day in the DS, while cumulative N2O emissions ranged from 60.53 to 220.86 mg N2O-N/kg soil/day in the RF, and 24.78 to 99.08 mg N2O-N/kg soil/day in the DS. In the RF samples, when compared to the use of urea alone, the combined use of manure and urea reduced N2O emissions but led to an increase in the DS samples. ATR-FTIR analysis showed that the combined use of manure and manure+urea increased the rate of microbial decomposition in the soils of the DS, but no such effect was observed in soils of the RF. We conclude that combining manure and urea fertilization has different effects on soils of the two ecoregions, and that RF farmers can reduce agricultural N2O emissions without compromising soil productivity and yield potential. [ABSTRACT FROM AUTHOR]