Evaluation of multistress tolerant maize varieties for sustainable intensification in northern Guinea Savanna of north eastern Nigeria

Maize productivity is limited by multiple stresses in the savannas of West and Central Africa. Field trials were conducted in northern Guinea savanna of Nigeria in 2011 and 2012 to evaluate the performance of multi-stress tolerant maize varieties. Thirteen varieties including Local Check replicated three times were tested in randomized complete block design. Plant and ear heights were significantly higher for LNTP x LNP-WC3 and 2004 TZE-W DTSTRC4 than POOL 18-SR, 2009 TZE-W POP-STR, EVDT 99-W STR; and EVDT 2000-Y STRQPM, respectively. Striga count was significantly lower for EVDT 99-W STR and LNTP x LNP-WC3 than all the other entries. Days to 50% tassel and 50% silk were each significantly earlier for EVDT 99STR W-STR QPM, DT-W STR SYN, EVDT-99W STR and 2009 TZEW DT STR than the Local Check. Anthesis Silk Interval (ASI) was significantly lower for TZE COMP3 DT-WC2, 2009 TZEW DT STR, and EVDT 99-W STR than Local Check. Number of ears plant-1 was significantly higher for 2008 DTMA-Y STR than Local Check. Grain yield ha-1 was significantly superior for DT-Y STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DTSTR C4, 2009 TZEW DT STR and EVDT 99-W STRQPM, respectively. Plant height was positively correlated with ASI and ear height, while ear height was positively associated with ears plant-1, days to 50% silk and 50% tassel. Grain yield ha-1 was positively correlated with ears plant-1, days to 50 % silk, days to 50% tassel and ear height, while ears plant-1 was negatively correlated with ear weight. Farmer selection criteria for acceptance of variety were in the order: Striga tolerance > nutrient value > drought tolerance > flour value > good taste > high yield > early maturity. The five varieties: DTY STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DT STRC4, 2009 TZEW DT STR and EVDT 99-W STRQPM satisfied farmers criteria and were promising and thus nominated for on-farm demonstration and subsequent adoption in the region

Causes of differences in seed quality among cowpea (Vigna unguiculata (L.) Walp) cultivars

Three cowpea cultivars differing in seed coat colour, IT83S-818 (white, black-eye), TVX 2724-01F (brown) and IT82D-32 (dark brown), were aged using the controlled deterioration method (20% seed moisture content and incubated at 40 oC) for 0, 1, 2 and 4 days. Time to 50 per cent germination (t50) and final germination percentage were determined to assess the vigour differences that exist among these cultivars. In unaged seeds, the white cultivar germinated quicker than the pigmented cultivars as a result of the characteristically higher rate of water uptake, which enhanced rapid hydration of the embryonic cells for quicker germination. When ageing progressed, however, the white cultivar germinated more slowly with a lower final germination percentage since the embryonic cells possibly became weaker and leaky leading to reduced vigour and eventually, loss of germinability. In contrast, the pigmented cultivars germinated more slowly before seeds were aged due to their slower rates of water uptake; germination became quicker as ageing progressed due to increasing softening of the seed coats. Thus, the pigmented cultivars showed decreases in the time to 50 per cent germination during ageing. They, however, retained high germination percentages throughout the ageing period, which is an indication of high vigour. These three cultivars, together with two other unpigmented cultivars, IT81D-1137 (white) and TVX 3236 (cream and brown) were subsequently examined for the incidence of disease pathogens. It was observed that the unpigmented cultivars had higher levels of the importasnt seed pathogens such as Fusarium species and Aspergillus flavus which cause reduction in germination. These seeds also showed susceptibility to mechanical damage caused by hand-beating of dry pods in sacs. These differences in behaviour between the two groups of cowpea cultivars, pigmented and unpigmented, were attributed to differences in tannin and lignin contents in their seed coats

Consumption trends of white cassava and consumer perceptions of yellow cassava in Ghana

Open Access JournalVitamin A deficiency has been one of the major nutritional problems for many countries where cassava is eaten as a major source of energy. In an attempt to help reduce the incidence of vitamin A deficiency, bio-fortified cassava which contains more pro-vitamin A carotenoids than the white cassava, has been introduced to such areas. This study therefore endeavored to find out how often Ghanaians ate cassava and its products, as well as what Ghanaian consumers knew about bio-fortified cassava and their willingness to consume it. A survey was done between the month of January and March using 287 participants in the Greater Accra Region of Ghana which gathered information on their demographics, and their frequencies of the consumption of cassava and its products. Data on the knowledge of the participants on yellow flesh cassava, and their willingness to accept it were also gathered. Logistic regression was used to determine the relationship between some demographic characteristics and knowledge and ‘willingness-to-accept’ biofortified cassava. The cassava product which was mostly consumed by the participants was gari. Sixty-three percent of the participants had no knowledge of bio-fortified cassava. About half of them were willing to accept the biofortified cassava, and more than half of the participants perceived that yellow cassava could be used for some white cassava products. Providing nutritional information and sensitizing consumers on the benefits of biofortified cassava can enhance its consumption in Ghana

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The response of cowpea (Vigna unguiculata L. Walp) seeds differing in seed coat colour to storage and reduced water availability during germination

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN003702 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

In vitro, greenhouse, and field assessment of cassava lines for resistance to anthracnose disease caused by colletotrichum gloeosporiodes f. sp. Manihotis

Fifty-three cassava lines were selected from breeding populations at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria and screened in vitro for resistance to cassava anthracnose disease (CAD). The in vitro inoculation of stem cuttings with the fungus Colletotrichum gloeosporioides f.sp. manihotis showed significant differences (p ± 0.05) in acervuli production and in the sensitivity of the cassava lines to the fungal infection after 7 days of incubation at 25 ◦C. Cassava lines 88/01084, 91/00595, 91/00475, 91/00344, 91/00684, 91/00313, 91/00422, and 91/00344 were highly resistant, with necrotic lesion sizes less than 7 mm. In contrast pedigree lines 88/02549, 89/0008, 91/00390 and 91/00402 were highly susceptible with the largest necrotic lesion size being greater than 20 mm. Ten cassava lines from the in vitro screening that showed varying levels of resistance to CAD were selected, based on their flowering abilities for diallel hydridization trials, and were further screened in greenhouse and field trials for CAD resistance. The greenhouse and field screening showed significant varietal differences (p ± 0.05) in sensitivity to the fungus. In all cases, the progeny lines showed correlated levels of resistance irrespective of the type of screening or assessments. Correlation analysis of the in vitro, greenhouse and field assessments showed that there was a good correspondence among all three methods of evaluating for CA

Anthracnose: an economic disease of cassava in Africa

Cassava anthracnose disease (CAD) caused by the fungus Colletotrichum gloeosporioides f.sp. manihotis has become one of the major economic diseases of cassava in Africa. The expansion of cassava production farmlands particularly in the humid rainfall zones of West and Central Africa has led to an increase in pathological problems of the crop. The increased epidemic levels of CAD had caused significant crop failure leading to severe food shortages for the poor subsistent farming population depending on the crop for their livelihood. This paper reviews the importance of the crop in terms of food security, CAD disease symptoms, epidemiology, yield losses and the possible control options within the frame work of integrated pest management systems (IPMS)