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Item Analysing the value chain for African leafy vegetables in Limpopo Province, South Africa.(Taylor and Francis, 2018-08-03) Senyolo, Grany M.; Wale, Edilegnaw; Ortmann, Gerald F.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.Item Factors influencing the adoption of climate-smart irrigation technologies for sustainable crop productivity by smallholder farmers in arid areas of South Africa.(MDPI, 2021-12-03) Serote, Batizi; Mokgehle, Salmina; Du Plooy, Christian; Mpandeli, Sylvester; Nhamo, Luxon; Senyolo, GranyThe adoption of climate-smart irrigation technologies amongst smallholder farmers generally remains low beside their role in combating food and nutrition security in a society and in climate change adaptation strategies. This study identified the factors influencing smallholder farmers’ decision to adopt Climate Smart Irrigation Technologies (CSIT) in the Limpopo Province of South Africa. Data were collected through the completion of a face-to-face structured questionnaire by 100 smallholder farmers selected through convenience and purposive sampling. A probit regression and OLS model were used to identify factors that influence the smallholder farmer’s decision to adopt CSIT and the level of adoption. The results indicated that only 46% of the smallholder farmers adopted climate-smart irrigation technologies and suggested that adoption is influenced positively by factors such as gender, age, district, farm size, staple food production and knowledge on CSIT. There is an urgent need for related stakeholders to transform the smallholder farmer subsector through improved extension services, training, adopting resilient crop varieties, promoting underutilized and nutrient-dense crops adapted to harsh local conditions, and other interventions. This should be done by promoting awareness to smallholder farmers regarding these interventions and new technologies that have the potential to improve rural livelihoods and enhance resilience and adaptation.Item Essential oil vapours suppress the development of anthracnose and enhance defence related and antioxidant enzyme activities in avocado fruit.(Elsevier B.V., 2013-02-03) Sellamuthu, Periyar Selvam; Sivakumar, Dharini; Soundy, Puffy; Korsten, LiseAnthracnose caused by Colletotrichum gloeosporioides is a major postharvest disease in avocados that causes significant losses during transportation and storage. Complete inhibition of the radial mycelia growth of C. gloeosporioides in vitro was observed with citronella or peppermint oils at 8 L plate−1 and thyme oil at 5 L plate−1. Thyme oil at 66.7 L L−1 significantly reduced anthracnose from 100% (untreated control) to 8.3% after 4 days, and to 13.9% after 6 days in artificially wounded and inoculated ‘Fuerte’ and ‘Hass’ fruit with C. gloeosporioides. GC/MS analysis revealed thymol (53.19% RA), menthol (41.62% RA) and citronellal (23.54% RA) as the dominant compounds in thyme, peppermint and citronella oils respectively. The activities of defence enzymes including chitinase, 1, 3--glucanase, phenylalanine ammonia-lyase and peroxidase were enhanced by thyme oil (66.7 L L−1) treatment and the level of total phenolics in thyme oil treated fruit was higher than that in untreated (control) fruit. In addition, the thyme oil (66.7 L L−1) treatment enhanced the antioxidant enzymes such as superoxide dismutase and catalase. These observations suggest that the effects of thyme oil on anthracnose in the avocado fruit are due to the elicitation of biochemical defence responses in the fruit and inducing the activities of antioxidant enzymes. Thus postharvest thyme oil treatment has positive effects on reducing anthracnose in avocados.Item Comparison of the contents of bioactive compounds and quality parameters in selected mango cultivars.(Wiley, 2013-08-28) Sellamuthu, Periyar Selvam; Denoya, Gabriela Ines; Sivakumar, Dharini; Polenta, Gustavo Alberto; Soundy, PuffyMango cultivars Tommy Atkins, Zill, Peach, Sabre, Rosa and Phiva were analyzed for their quality parameters (fruit weight, flesh color chroma, L, h0, total soluble solid [TSS]/titratable acidity [TA], firmness), bioactive compounds (total phenols, carotenoids, ascorbic acid, antioxidant activity) and polyphenol oxidase (PPO) activity. Cv. Sabre showed highest total phenolic content (76.43 mg gallic acid/ 100 g FW), carotenoids (9.90 mg/100 g of FW), ascorbic acid content (69.71 mg/ 100 g of FW) and antioxidant activity (1.2 mg of gallic acid/g of FW), whereas cv. Peach mango contained lower bioactive compounds. Multivariate principal component analysis analysis showed higher concentration of bioactive compounds in cv. Sabre mango, whereas cv. Tommy Atkins was firm and heavier. Cv. Rosa and Phiva were moderately rich in bioactive compounds and lower in fruit weight and firmness, whereas cv. Peach was higher in TSS/ TA. The PPO activity was higher in cvs. Rosa and Zill.Item Influence of postharvest storage temperature and duration on quality of baby spinach.(American Society for Horticultural Science, 2015-10-01) Mudau, Ambani R.; Nkomo, Mpumelelo M.; Soundy, Puffy; Araya, Hintsa T.; Ngezimana, Wonder; Mudau, Fhatuwani N.Spinach (Spinacia oleracea) is a member of the Amaranthaceae family. Baby spinach leaves have a very high respiration rate, thus postharvest quality is affected mostly by tissue decay and the development of off-odors. Thus, this study was conducted to investigate the influence of storage temperature and time on the postharvest quality of baby spinach. Baby spinach leaves were harvested 36 days after planting and subsequently stored at 4 and 22 C for 0, 2, 4, 6, 8, 10, or 12 days. Thereafter, the leaves were incubated for 72 hours at 40 C to dry. Minerals, trace elements, total phenols, total carotenoids, flavonoids, and antioxidant activities were measured. Concentration of magnesium (Mg), zinc (Zn), and iron (Fe) were declined after 8 days of storage at 4C, while at 22 C they declined after 2 days of storage. Mg, Zn, and Fe revealed a similar trend with significantly higher carotenoids found up to 6 days in storage at 4 C, while at 22 C the carotenoid levels declined after only 2 days. Total phenolic compounds gradually decreased in samples stored at 4 C. However, samples stored at 22 C showed a rapid decrease after 4 days. Both total antioxidant activities and vitamin C content showed a similar trend, with the content remaining constant at 4 C and decreasing after 6 days, whereas the total antioxidant activities and vitamin C for leaves stored at 22 C decreased immediately after 2 days. Results demonstrated that quality of baby spinach deteriorates as storage time and temperature increase.Item Activity-guided isolation and identification of the major antioxidant and anticancer compounds from a commercial pelargonium sidoides tincture.(Springer, 2015-08-20) Pereira, Andreia; Bester, Megan; Soundy, Puffy; Apostolides, ZenoExtracts prepared from the roots of Pelargonium sidoides (DC) are commercially available for the treatment of respiratory related conditions. Recently, a commercial radix mother tincture of this plant was shown to have both antioxidant and anticancer effects especially related to the G0/G1 block in the Jurkat E6.1 cell line (unpublished results). Fractions were prepared by semipreparative HPLC, and their antioxidant and anticancer activities were determined. The more hydrophilic fractions isolated namely F6–F12 were all found to have strong reducing capacities and were able to scavenge peroxyl radicals. In the human lung cell line, NCI-H460, significant cellular antioxidant effects were observed. Anticancer activity was evaluated in the NCI-pre-screen panel (NCIH460, MCF-7 and SF-268) and the Jurkat E6.1 cell line. Fractions F7, F9, and F12 were found to inhibit the cell growth of these four cell lines (p\0.05), especially the Jurkat E6.1 cell line with the sulforhodamine B assay. Mass spectrometry analysis revealed that these active fractions contained several polyphenolic compounds such as gallic acid, trihydroxycoumarin, dihydroxycoumarin sulfates, proanthocyanidins, and phenolic glycosides. A phenolic acid glycoside sulfate not previously shown in P. sidoides extracts was also isolated. In conclusion, the antioxidant and/or anticancer activity of the P. sidoides tincture may be attributed to the presence of these polyphenolics.Item Response of baby spinach (Spinacia oleracea L.) to photoselective nettings on growth and postharvest quality.(American Society for Horticultural Science, 2017-05-01) Mudau, Ambani R.; Soundy, Puffy; Mudau, Fhatuwani N.Manipulation of microenvironments by means of photo selective nettings is widely used to improve the productivity and quality of high-value vegetables. The aim of this study was to investigate the effect of photos elective nettings on growth, productivity, and postharvest quality attributes of baby spinach. Baby spinach cv. Ohio was grown from seeds, and the trial was repeated. Plants were planted in an open field (control) and under closed nets, viz., black, pearl, yellow, and red nets. At harvest, baby spinach leaves were subjected to 4, 10, and 20 8C storage temperatures for 12 days. Crops grown under black nets and stored at 4 8C retained higher level of antioxidant activity (0.23 g·kgL1), whereas the least level of antioxidant activity was observed in baby spinach grown under red and yellow shade nets (0.01 g·kgL1). Similar trend was evident with flavonoid content where baby spinach leaves grown under black nets maintained high level of flavonoids at 4, 10, and 20 8C during storage period compared with other shade nets and the control. The study control showed a better potential in retaining antioxidant activity over red and yellow shade nets. Results showed that black shade nettings have the potential to reduce water loss, decay incidents, and maintain flavonoid content and antioxidant activity followed by pearl and yellow nets.Item Nitrogen application and leaf harvesting improves yield and nutritional quality of beetroot.(American Society for Horticultural Science, 2017-06-27) Mampa, Salfina S.; Maboko, Martin M.; Soundy, Puffy; Sivakumar, DhariniBeetroot (Beta vulgaris), commonly known as table beet, is used as a staple in the diet of many people through the consumption of the entire plant, leaf, and the root. The objective of this study was to assess the effects of nitrogen (N) application and leaf harvest percentage on the yield and quality of roots and leaves of beetroot. The treatment design was a randomized complete block design with five levels of N (0, 60, 90, 120, and 150 kghaL1) combined with three leaf harvest percentages (0, 30, and 50) and replicated three times. The first leaf harvest was initiated 35 days after transplanting (DAT) by removing the outer matured leaves and the second harvest occurred 80 DAT by removing all the leaves. The results showed increases in leaf and root yield with an increase in N application. Nitrogen application at 90 and 120 kghaL1 increased fresh leaf weight, leaf number, and fresh and dry root weight, including root diameter and length with the exception of leaf area which was significantly higher at 120 kghaL1 N. Magnesium and iron leaf content, and N root content were significantly improved by the application of 120 kghaL1 N. Leaf harvest percentage did not have a significant effect on leaf yield or leaf and root mineral content. However, dry root weight was significantly reduced by the 50% leaf harvest. Leaf harvest at 30% or 50% increased total protein content of the roots of beetroot, whereas an increase in N application decreased concentration of total proteins. Results demonstrate that leaf and root yield, as well as magnesium, zinc, and iron leaf content, increased with the application of 120 kghaL1 N, whereas 30% leaf harvest did not negatively affect root yield.Item Deficit irrigation improves phenolic content and antioxidant activity in leafy lettuce varieties.(Wiley, 2017-11-04) Malejane, Dunsfort N.; Tinyani, Peter P.; Soundy, Puffy; Sultanbawa, Yasmina; Sivakuma, DhariniThis study investigated the effect of deficit irrigation at three management allowable depletion levels (MAD) 25%, 50%, and 75% on phytochemicals, ascorbic acid, antioxidant activity, glucose, fructose, and fresh and dry mass in two green leafy lettuce cultivars (Lollo Bionda and Vera) at harvest. Genotype response was observed during deficit irrigation on fresh and dry mass at harvest. Vera revealed similar fresh mass at MAD levels 25% and 50%. Chicoric acid, caftaric acid, and chlorogenic and caffeic acid tended to increase at 50% MAD, while kaempferol, quercetin, and myricetin increased at 75% MAD in both cultivars indicating increasing antioxidant properties. Ascorbic acid content declined with increasing MAD levels and no definite trend on β-carotene content was noted in these cultivars with respect to MAD irrigation. Deficit irrigation at 50% and 70% increased glucose concentration in cv. Lollo Bionda. Deficit irrigation influences the abiotic stress condition that stimulates the biosynthesis of phytochemicals in plants and improves crop quality. However, deficit irrigation can affect marketable crop yield. Based on findings of this study, the lettuce cv. Vera can be recommended as a suitable cultivar for deficit irrigation (at MAD 50% levels) for improving dietary phytochemicals and crop quality without compromising fresh mass for marketing.Item Impact of transportation, storage, and retail shelf conditions on lettuce quality and phytonutrients losses in the supply chain.(Wiley, 2018-04-27) Managa, Millicent G.; Tinyani, Peter P.; Senyolo, Grany M.; Soundy, Puffy; Sultanbawa, Yasmina; Sivakumar, DhariniThis study was initiated to investigate the impact of transportation, storage, and retail shelf conditions on lettuce quality and phytonutrients losses in the urban fresh produce market supply chain. Reducing postharvest losses is a priority to reduce the loss of the dietary-based phytonutrients and to improve the health of the consumers. Limited information is available in South Africa related to the postharvest and nutrition loss in the urban fresh produce market supply chain. In this study, we quantified the postharvest losses, changes in phytochemicals, and loss of minerals in lettuce at different points of Tshwane Fresh Produce Market supply chain. Lettuce supply to the Tshwane Fresh Produce Market from two different provinces, Gauteng and Northwest, were included in this study for comparison. Lettuce from the two provinces was collected from five different farms. The loss of fresh weight, changes in visual quality, Phyto nutrition properties, and economic loss of lettuce at the supply chain points: (a) transport; (b) storage; (c) and at the retail shelf was investigated. Five boxes of lettuce per supply chain point from Gauteng and Northwest provinces were randomly selected. The results indicated that the high temperature (25°C) and low RH (40%) at the retail shelf affected the weight, overall quality, and Phyto nutrition properties of lettuce. Cumulative economic loss was higher at the retail shelf due to the inferior quality of lettuce. The study identified where major quality and Phyto nutrition losses occur during marketing. The study demonstrated to identify the where major food and nutritional loss losses occur during marketing. This information will significantly benefit food sustainability by introducing technologies to manage food and nutrition losses.Item Variety-specific responses of lettuce grown in a gravel-film technique closed hydroponic system to N supply on yield, morphology, phytochemicals, mineral content and safety.(Elsevier Ltd., 2018-05-07) Mampholo, Bevly M.; Maboko, Martin M.; Soundy, Puffy; Sivakumar, DhariniUtilization of nitrogen (N) element is a common practice used to reach profitable yields in horticultural crops and N supply can be used as a tool to manipulate the enhancement of phytochemicals and minerals in vegetable crops to address consumer-oriented quality production. Hence the study was aimed to investigate the effect of N application on leaf morphology, ascorbic acid content, phenolic acids, flavonoids, mineral content, and nitrate residues in three lettuce varieties (two green leafy lettuce, Multigreen 1 and Multigreen 3; one red leafy lettuce, Multired 4) grown in a closed hydroponic system (gravel-film) at harvest. Nitrogen was applied as ammonium nitrate (NH4NO3) at six different concentrations of 0, 60, 90, 120, 150 and 180 mg L–1. The results obtained during 2015 and 2016 seasons were similar and demonstrated variety dependent responses with respect to different N application rates. Multigreen 3 was more sensitive to N supply and showed higher amount of nitrate residue at harvest. Variety Multired 4 was less sensitive to N supply followed by Multigreen 1. Although N supply at 120 mg L–1 improved the yield and the number of leaves in Multigreen 3, overall 90 mg L–1 can be recommended for these lettuce varieties to improve the yield and the accumulation of ascorbic acid content, phenolic acids mainly caffeic, caftaric acids, quercetin (the important flavonoid in lettuce), and Fe and Mn contents. Furthermore, the concentration of 90 mg L–1 improved the antioxidant property (FRAP and ABTS+) and reduced the nitrate accumulation, ensuring safe food for consumers.Item Phylogenetically diverse group of native bacterial symbionts isolatedfrom root nodules of groundnut (Arachis hypogaea L.) in South Africa.(Elsevier GmbH., 2017-02-12) Jaiswal, Sanjay K.; Msimbira, Levini A.; Dakora, Felix D.Groundnut is an economically important N2-fixing legume that can contribute about 100–190 kg N ha−1to cropping systems. In this study, groundnut-nodulating native rhizobia in South African soils were isolated from root nodules. Genetic analysis of isolates was done using restriction fragment length polymorphism (RFLP)-PCR of the intergenic spacer (IGS) region of 16S-23S rDNA. A total of 26 IGS types were detected with band sizes ranging from 471 to 1415 bp. The rhizobial isolates were grouped into five main clusters with Jaccard’s similarity coefficient of 0.00–1.00, and 35 restriction types in a UPGMA dendrogram. Partial sequence analysis of the 16S rDNA, IGS of 16S rDNA-23S rDNA, atpD, gyrB, gltA, glnIIand symbiotic nifH and nodC genes obtained for representative isolates of each RFLP-cluster showed that these native groundnut-nodulating rhizobia were phylogenetically diverse, thus confirming the extent of promiscuity of this legume. Concatenated gene sequence analysis showed that most isolates did notalign with known type strains and may represent new species from South Africa. This underscored the high genetic variability associated with groundnut Rhizobium and Bradyrhizobium in South African soils, band the possible presence of a reservoir of novel groundnut-nodulating Bradyrhizobium and Rhizobiumin the country.Item Symbiotic performance, shoot biomass and water-use efficiency of three groundnut (Arachis hypogaea L.) genotypes in response to phosphorus supply under field conditions in Ethiopia.(Higher Education Press, 2020-05-27) Muhaba, Sofiya K.; Dakora, Felix D.Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism, respiration and photosynthesis and its supply at low levels can affect legume nodulation, N2 fixation, and C assimilation. A two-year field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth, symbiotic N2 nutrition, grain yield and water-use efficiency of three groundnut genotypes. Supplying P to the genotypes significantly increased their shoot biomass, symbiotic performance, grain yield, and C accumulation. There was, however, no effect on shoot δ13C values in either year. Compared to the zero-P control, supplying 40 kg$ha–1 P markedly increased shoot biomass by 77% and 66% in 2012 and 2013, respectively. In both years, groundnut grain yields were much higher at 20 and 30 kg$ha–1 P. Phosphorus supply markedly reduced shoot δ15N values and increased the %Ndfa and amount of Nfixed, indicating the direct involvement of P in promoting N2 fixation in nodulated groundnut. The three genotypes differed significantly in δ15N, %Ndfa, N-fixed, grain yield, C concentration, and δ13C. The phosphorus genotype interaction was also significant for shoot DM, N content, N-fixed and soil N uptake.Item African origin of bradyrhizobium populations nodulating bambara groundnut (Vigna subterranea L. Verdc) in Ghanaian and South African soils.(Public Library of Science, 2017-09-25) Puozaa, Doris K.; Jaiswal, Sanjay K.; Dakora, Felix D.Flavonoids secreted by legumes play a major role as signal molecules for attracting compatible rhizobia. The aim of this study was to assess and understand the diversity of microsymbionts nodulating Bambara groundnut (Vigna subterranea L. Verdc.) landraces of different seedcoat colours using restriction fragment length polymorphism and phylogenetic analysis. Seedcoat pigmentation of landraces had effect on the diversity of microsymbionts of Bambara groundnut. Even when planted together in one hole, nodulating bradyrhizobia clustered differently. For example, 16S rDNA-RFLP typing of rhizobial samples TUTVSBLM.I, TUTVSCRM.I and TUTVSRDM.I originating respectively from Black, Cream and Red landraces that were co-planted in the same hole at Manga in the Sudanosahelian savanna, as well as TUTVSCRK.I and TUTVSRDK.I respectively from Cream and Red landraces co-planted at Kpalisogu in the Guinea savanna, revealed different 16S rDNA- RFLP types. Phylogenetic analysis of 16S rDNA, glnII, recA and atpD sequences showed that Vigna subterranea was nodulated specifically by a diverse group of Bradyrhizobium species (e.g. Bradyrhizobium vignae, and a novel group of Bradyrhizobium spp.) in soils from Ghana and South Africa. The recA gene phylogeny showed incongruency with the other housekeeping genes, indicating the possibility of lateral gene transfer and/or recombination events. The grouping of isolates according to symbiotic gene (nifH and nodD) phylogenies revealed inter- and intra-specific symbiotic plasmid transfer and different evolutionary history. The results also showed that a cropping history and physico-chemical environment of soils increased bradyrhizobial diversity in Ghana and South Africa.Item Seed coat metabolite profiling of cowpea (Vigna unguiculata L. Walp.) accessions from Ghana using UPLC-PDA-QTOF-MS and chemometrics.(Taylor and Francis, 2018-11-12) Tsamo, Armelle Tontsa; Mohammed, Haruna; Mohammed, Mustapha; Ndibewu, Peter Papoh; Dakora, Felix DapareCowpea (Vigna unguiculata L. Walp.) is an important grain legume in Africa exhibiting high morpho-genetic diversity. However, not much information exists on the phytochemical profiles of its hulls. This study explored the metabolite profiles of seedcoats from thirteen cowpea accessions of varying phenotypes using UPLC-QTOF-MS and chemometric analysis. A total of 34 secondary metabolites were identified, which comprised phenolic acids, flavonoids, anthocyanins, sphingolipids and fatty acids. Quantification of selected phenolic compounds revealed marked variations among the cowpea accessions. The chemical profiles of the test accessions were distinguished by multivariate analysis, and the results revealed a marked influence of seed-coat pigmentation on the observed differences in their metabolite profiles. Moreover, delphinidin (traces to 2257.6 mg/g), catechin glucoside (traces to 2840.6 mg/g), catechin (traces to 2089.2 mg/g) and epicatechin (26.3 to 3222.7 mg/g) contributed to the segregation amongst the studied samples. The concentrations of the discriminant metabolites were greater in the dark seeded cowpeas compared to their lighter seeded counterparts. The findings represent a useful contribution to the literature on cowpea seed coat metabolites, and also reveal their potential for use in the development of food and pharmaceutical products.Item Distribution and phylogeny of microsymbionts associated with cowpea (Vigna unguiculata) nodulation in three agroecological regions of Mozambique.(American Society for Microbiology, 2017-11-01) Chidebe, Ifeoma N.; Jaiswal, Sanjay K.; Dakora, Felix D.Cowpea derives most of its N nutrition from biological nitrogen fixation (BNF) via symbiotic bacteroids in root nodules. In Sub-Saharan Africa, the diversity and biogeographic distribution of bacterial microsymbionts nodulating cowpea and other indigenous legumes are not well understood, though needed for increased legume production. The aim of this study was to describe the distribution and phylogenies of rhizobia at different agroecological regions of Mozambique using PCR of the BOX element (BOX-PCR), restriction fragment length polymorphism of the internal transcribed spacer (ITS-RFLP), and sequence analysis of ribosomal, symbiotic, and housekeeping genes. A total of 122 microsymbionts isolated from two cowpea varieties (IT-1263 and IT-18) grouped into 17 clades within the BOX-PCR dendrogram. The PCR-ITS analysis yielded 17 ITS types for the bacterial isolates, while ITS-RFLP analysis placed all test isolates in six distinct clusters (I to VI). BLAST sequence analysis of 16S rRNA and four housekeeping genes (glnII, gyrB, recA, and rpoB) showed their alignment with Rhizobium and Bradyrhizobium species. The results revealed a group of highly diverse and adapted cowpea-nodulating microsymbionts which included Bradyrhizobium pachyrhizi, Bradyrhizobium arachidis, Bradyrhizobium yuanmingense, and a novel Bradyrhizobium sp., as well as Rhizobium tropici, Rhizobium pusense, and Neorhizobium galegae in Mozambican soils. Discordances observed in single-gene phylogenies could be attributed to horizontal gene transfer and/or subsequent recombinations of the genes. Natural deletion of 60 bp of the gyrB region was observed in isolate TUTVU7; however, this deletion effect on DNA gyrase function still needs to be confirmed. The inconsistency of nifH with core gene phylogenies suggested differences in the evolutionary history of both chromosomal and symbiotic genes. IMPORTANCE A diverse group of both Bradyrhizobium and Rhizobium species responsible for cowpea nodulation in Mozambique was found in this study. Future studies could prove useful in evaluating these bacterial isolates for symbiotic efficiency and strain competitiveness in Mozambican soils.Item Insights into nitrogen fixing traits and population structure analyses in cowpea (Vigna unguiculata L. Walp) accessions grown in Ghana.(Springer, 2020-05-12) Mohammed, Haruna; Jaiswal, Sanjay K.; Mohammed, Mustapha; Mbah, Glory C.; Dakora, Felix D.With legumes, symbiotic N2 fixation can meet the species N demand and reduce the over-reliance on chemical fertilizers in tropical regions where N deficiency is a major factor limiting crop yields and increased agricultural sustainability. Therefore, to optimize the use of cowpea (Vigna unguiculata L. Walp) germplasm in effective breeding, evaluation of genetic diversity and quantification of N2 fixation are essential prerequisites. The aim of this study was to explore the level of diversity using SSR markers and N2-fixing traits in a set of cowpea germplasm grown in Ghana. We analysed 49 cowpea accessions collected from Northern Ghana using qualitative vegetative and N2 fixation traits, and simple sequence repeat (SSR) markers. Experimental field results revealed considerable morpho-physiological variation for plant growth habits, grain yield and symbiotic performance between and among the cowpea accessions. Results from both the 15N natural abundance and ureides in the xylem sap were able to descriminate between high and low levels of N2 fixation in cowpea accessions. Five subpopulations were identified within accessions inferred from STRUCTURE 2.3.4. A general linear model was used to assess the association of SSR markers with N2–fixing traits. There were significant (p B 0.05) links between SSR markers and symbiosis-related traits such as nodule number, nodule dry weight, shoot dry weight, N-fixed, N derived from air (Ndfa), and relative uried-N (RU-N).Item Nature and mechanisms of aluminium toxicity, tolerance and amelioration in symbiotic legumes and rhizobia.(Springer, 2016-02-12) Jaiswal, Sanjay K.; Naamala, Judith; Dakora, Felix D.Recent findings on the effect of aluminium (Al) on the functioning of legumes and their associated microsymbionts are reviewed here. Al represents 7% of solid matter in the Earth’s crust and is an important abiotic factor that alters microbial and plant functioning at very early stages. The trivalent Al (Al3+) dominates at pH < 5 in soils and becomes a constraint to legume productivity through its lethal effect on rhizobia, the host plant and their interaction. Al3+ has lethal effects on many aspects of the rhizobia/legume symbiosis, which include a decrease in root elongation and root hair formation, lowered soil rhizobial population, and suppression of nitrogen metabolism involving nitrate reduction, nitrite reduction, nitrogenase activity and the functioning of uptake of hydrogenases (Hup), ultimately impairing the N2 fixation process. At the molecular level, Al is known to suppress the expression of nodulation genes in symbiotic rhizobia, as well as the induction of genes for the formation of hexokinase, phosphodiesterase, phosphooxidase and acid/alkaline phosphatase. Al toxicity can also induce the accumulation of reactive oxygen species and callose, in addition to lipoperoxidation in the legume root elongation zone. Al tolerance in plants can be achieved through over-expression of citrate synthase gene in roots and/or the synthesis and release of organic acids that reverse Al-induced changes in proteins, as well as metabolic regulation by plant-secreted microRNAs. In contrast, Al tolerance in symbiotic rhizobia is attained via the production of exopolysaccharides, the synthesis of siderophores that reduce Al uptake, induction of efflux pumps resistant to heavy metals and the expression of metal-inducible (dmeRF) gene clusters in symbiotic Rhizobiaceae. In soils, Al toxicity is usually ameliorated through liming, organic matter supply and use of Al-tolerant species. Our current understanding of crop productivity in high Al soils suggests that a much greater future accumulation of Al is likely to occur in agricultural soils globally if crop irrigation is increased under a changing climate.Item Assessing host range, symbiotic effectiveness, and photosynthetic rates induced by native soybean rhizobia isolated from Mozambican and South African soils.(Springer, 2016-10-21) Gyogluu, Cynthia; Mohammed, Mustapha; Jaiswal, Sanjay K.; Kyei-Boahen, Stephen; Dakora, Felix D.identifying rhizobial strains with potential for use as inoculants. In this study, 10 native soybean rhizobia isolated from Mozambican and South African soils were evaluated for host range, symbiotic effectiveness and ability to induce high rates of photosynthesis leading to enhanced plant growth in cowpea (Vigna unguiculata L. Walp.), Bambara groundnut (Vigna subterranean L. Verdc.), Kersting’s groundnut (Macrotyloma geocarpum Harm) and soybean (Glycine max L. Merr). The test isolates had different growth rates and colony sizes. Molecular analysis based on enterobacterial repetitive intergenic consensus (ERIC)-PCR revealed high genetic diversity among the test isolates. The results further showed that isolate TUTLBC2B failed to elicit nodulation in all test plants, just as TUTNSN2A and TUTDAIAP3B were also unable to nodulate cowpea, Kersting’s bean and Bambara groundnut. Although the remaining strains formed ineffective nodules on cowpea and Kersting’s bean, they induced effective nodules on Bambara groundnut and the two soybean genotypes. Bacterial stimulation of nodule numbers, nodule dry weights and photosynthetic rates was generally greater with isolates TUTRSRH3A, TUTM19373A, TUTMCJ7B, TUTRLR3B and TUTRJN5A. As a result, these isolates elicited significantly increased accumulation of biomass in shoots and whole plants of Bambara groundnut and the two soybean genotypes. Whole-plant symbiotic nitrogen (N) of soybean and Bambara groundnut was highest for the commercial strains CB756 and WB74, as well as for TUTRLR3B, TUTMCJ7B and TUTRSRH3A, suggesting that the three native rhizobial isolates have potential for use as inoculants.Item Grain yield of common bean (Phaseolus vulgaris L.) varieties is markedly increased by rhizobial inoculation and phosphorus application in Ethiopia.(Springer, 2017-12-19) Samago, Tarekegn Yoseph; Anniye, Endalkachew W.; Dakora, Felix D.A field experiment was conducted to assess plant growth, symbiotic performance and grain yield of common bean in response to rhizobial incoculation and phosphorus application at Galalicha in Southern Ethiopia during the 2012 and 2013 cropping seasons under rain-fed conditions. The treatments consisted of 2 released common bean varieties (HawassaDume and Ibbado), 3 levels of Rhizobium inoculation (uninoculated, inoculated with strain HB-429 or GT-9) and 4 levels of phosphorus application (0, 10, 20 and 30 kg P ha−1) using a split-split plot design with four replications. Here, phosphorus levels, Rhizobium inoculation and common bean varieties were assigned as main, sub- and sub-sub treatments, respectively. The results revealed marked varietal differences in plant growth, grain yield and symbiotic performance. Of the two common bean varieties studied, Hawassa Dume generally showed superior performance in most measured parameters in 2013. Rhizobium inoculation significantly (p ≤ 0.05) increased plant growth, symbiotic performance and grain yield. Applying Rhizobium strain HB-429 to bean crop respectively increased plant growth, %Ndfa, amount of N-fixed and grain yield by 19, 17, 54 and 48% over uninoculated control. Similarly, the application of 20 kg P ha−1 to bean plants respectively resulted in 36, 20, 96 and 143% increase in plant growth, %Ndfa, Nfixed and grain yield when compared to the control. These results clearly indicate that plant growth, symbiotic performance and grain yield of common bean can be significantly increased by Rhizobium inoculation and phosphorus fertilization in Ethiopia. Rhizobium inoculants are a cheaper source of nitrogen than chemical fertilizers and when combined with moderate phosphorus application can markedly increase grain yield for resource-poor farmers.