Welcome to the International Institute of Tropical Agriculture Research Repository
Journal and Journal Articles: Recent submissions
Now showing items 641-660 of 5266
-
Gliricidia agroforestry technology adoption potential in selected dryland areas of Dodoma region, Tanzania
(2020-07-20)Declining soil fertility is one of the major problems facing producers of field crops in most dryland areas of Sub-Saharan Africa. In response to the declining soil fertility, extensive participatory research has been undertaken by the World Agroforestry (ICRAF) and smallholder farmers in Dodoma region, Tanzania. The research has, amongst others, led to the development of Gliricidia agroforestry technology. The positive impact of Gliricidia intercropping on crop yields has been established. However, ... -
Banana biomass estimation and yield forecasting from non-destructive measurements for two contrasting cultivars and water regimes
(2020-09-21)The largest abiotic constraint threatening banana (Musa spp.) production is water stress, impacting biomass buildup and yields; however, so far no studies have investigated the effects of water stress on allometric equations in banana. Weighted least square regression models were built for (i) estimating aboveground vegetative dry biomass (ABGVD) and corm dry biomass (cormD) and (ii) forecasting bunch fresh weight (bunchF), based on non-destructive parameters for two cultivars, Mchare Huti-Green ... -
Genotype x environment interaction analysis of soybean (Glycine max (L.) Merrill) grain yield across production environments in southern Africa
(2020-10-01)Development of high yielding and stable cultivars of various crops across the Southern African Development Community (SADC) member states is in line with the recently enacted SADC’s seed harmonisation act. This study, therefore, focused on evaluating soybean [Glycine max (L.) Merrill] lines developed by the International Institute of Tropical Agriculture (IITA) for yield and stability across SADC test environments using the additive main effects and multiplicative interaction (AMMI) analysis. ... -
Maize hybrids response to high plant density in the Guinea savannah of Nigeria
(2020-07-07)Several maize (Zea mays L.) hybrids have been developed and commercialized in the Nigeria savannas, but limited informationis available on how they perform at plant densities higher than the recommended density of 53,333 plants ha-1. Therefore, field trials were conducted in northern Nigeria in 2015 and 2016 at two locations with contrasting rainfall amount to evaluate the performance of selected maize hybrids at plant densities of 53,333 and 88,888 plants ha-1. All maize hybrids had higher grain ... -
Susceptibility of ten tomato cultivars to attack by Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) under laboratory conditions
(2020-07-28)We evaluated, in a laboratory experiment, the susceptibility of 10 tomato cultivars to the attack by the tomato red spider mite Tetranychus evansi, an invasive pest of this crop in Benin. Among the 10 cultivars tested, six were imported (i.e. Roma VF, Tima, Rio Grande, Buffalo, Petomech, and TLCV15) and four local (i.e. Akikon, Tounvi, TomL4, and Kèkèfo). Leaf disks (2.5 cm diameter) excised from leaves of tested cultivars, and placed upper side down on top of water-soaked cotton wool laying in ... -
Towards sustainable yield improvement: field inoculation of soybean with Bradyrhizobium and co‑inoculation with Azospirillum in Mozambique
(2020-11)The effects of sole inoculation of soybean (Glycine max L. Merrill) with Bradyrhizobium and co-inoculation with Bradyrhizobium and Azospirillum on nodulation, plant growth and yields were investigated in the 2013/2014 and 2014/2015 cropping seasons under field conditions in Mozambique. The treatments included (1) Control (non-inoculated control, with symbiosis depending on indigenous rhizobia), (2) Urea (non-inoculated, receiving 200 kg ha−1 of N), (3) Sole inoculation with B. diazoefficiens strain ... -
Life history and temperature-dependence of cassava-colonising populations of Bemisia tabaci
(2020-06-17)The whiteflies belonging to the species group Bemisia tabaci transmit viruses that are the greatest constraint to the production of cassava, Africa’s most important food security crop. We studied the life history of an endemic African population of B. tabaci SSA-ESA at six constant temperatures (16, 20, 24, 28, 32, 36 °C) in controlled environment chambers, and for 10 generations in the field. Oviposition occurred between 20 and 28 °C, with highest fecundity (114.5 ± 88.2) eggs per female at 20 ... -
Evaluation of nutritional properties of cassava-legumes snacks for domestic consumption: consumer acceptance and willingness to pay in Zambia
(2020-08-25)High-quality cassava flour (HQCF) is a cheaper alternative to wheat in the production of snacks. This study assessed the nutritional properties and consumer acceptability of cassava-legume snacks in Zambia. Cassava snacks were made from 100% HQCF, 50:50 cassava-soybean flour blend, 50:50 cassava-cowpea flour blend and 100% wheat flour as the control. The samples were analyzed for nutritional, functional and anti-nutritional properties using standard laboratory methods. Also, a well-outlined ... -
Boiled yam end-user preferences and implications for trait evaluation
(2020-07-25)This study aimed to establish the quality characteristics of raw and boiled yam by involving stakeholders along the food chain using a methodology that includes a state of knowledge review, focus group discussion and individual interviews, participatory processing diagnosis with processors and consumer testing. Predictive characteristics of yam for producing a high‐ and low‐quality boiled yam were related to morphological or physicochemical characteristics: peeled yam discoloration and mucilage ... -
Soil quality and soil fertility status in major soil groups at the Tombel area, South-West Cameroon
(2020-02)Among the greatest challenges of Sub-Saharan Africa is the need for more crop production for supplying the increasing demand of its growing population. For this purpose, knowledge on soil resources and their agricultural potentials is important for defining proper and appropriate land use and management. We thus investigated on the status of soil fertility in Tombel area, in order to produce such knowledge through understanding and monitoring the impact of physicochemical properties of soil. Diverse ... -
Potato cyst nematodes: a new threat to potato production in east Africa
(2020)Potato cyst nematodes (PCN), such as Globodera rostochiensis and Globodera pallida, are quarantine restricted pests of potato causing major yield and financial losses to farmers. G. rostochiensis was first reported from Kenya’s key potato growing area in 2015. We sought to determine the diversity, prevalence and distribution of PCN species across the country by conducting a country-wide survey between 2016 and 2018, which included a more focused, follow-up assessment in three key potato growing ... -
Acetylcholinesterase (ace‑1R) target site mutation G119S and resistance to carbamates in Anopheles gambiae (sensu lato) populations from Mali
(2020)Background The long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are major malaria vector control strategies in Mali. The success of control strategies depends on a better understanding of the status of malaria vectors with respect to the insecticides used. In this study we evaluate the level of resistance of Anopheles gambiae (sensu lato) to bendiocarb and the molecular mechanism that underlies it. Methods Larvae of An. gambiae (s.l.) were collected ... -
Fungal diversity within organic and conventional farming systems in Central Highlands of Kenya
(2020)Fungal diversity in agro-ecosystems is influenced by various factors related to soil and crop management practices. However, due to the complexity in fungal cultivation, only a limited number has been extensively studied. In this study, amplicon sequencing of the Internal Transcribed Spacer (ITS) region was used to explore their diversity and composition within long-term farming system comparison trials at Chuka and Thika in Kenya. Sequences were grouped into operational taxonomic units (OTUs) at ... -
Founder events influence structures of Aspergillus flavus populations
(2020-08)In warm regions, agricultural fields are occupied by complex Aspergillus flavus communities composed of isolates in many vegetative compatibility groups (VCGs) with varying abilities to produce highly toxic, carcinogenic aflatoxins. Aflatoxin contamination is reduced with biocontrol products that enable atoxigenic isolates from atoxigenic VCGs to dominate the population. Shifts in VCG frequencies similar to those caused by the introduction of biocontrol isolates were detected in Sonora, Mexico, ... -
Double burden of malnutrition: evidence from a selected Nigerian population
(2020-09-01)Indices reflecting the double burden of malnutrition in sub-Saharan Africa are increasing. Evidence to support this claim in households of Africa’s most populous country—Nigeria—is scant. This study, therefore, presents results from a study of mother-child pairs sampled from Akwa Ibom State in the southern region of Nigeria. Anthropometric measures for 660 mother-child pairs were collected according to standard procedures. Indices were expressed as the standard deviation of units from the median ... -
Taxonomic revision of the afrotropical Phytomia gerin-meneville (Diptera: syrphidae)
(2020)The Afrotropical representatives of the hoverfly genus Phytomia Guérin-Méneville (Diptera) are revised. In total, 19 species are recognized of which three are new to science: Phytomia austeni sp. nov., P. memnon sp. nov., and P. pallida sp. nov. Phytomia neavei Bezzi is considered a junior synonym of P. kroeberi (Bezzi), P. noctilio Speiser a junior synonym of P. pubipennis Bezzi, and P. ephippium Bezzi a junior synonym of P. melas (Bezzi). Lectotypes are designated for the following species: ... -
Witchweed [Striga hermonthica (Del.) Benth] control using imazapyr seed coating in maize hybrids in the Nigerian savannah
(2020-08)Witchweed [Striga hermonthica (Del.) Benth] is a major parasitic weed of most cereal crops in Africa, including maize. Seed treatment with low doses of acetolactate synthase–inhibiting herbicides, such as imazapyr, was introduced in the 1990s to control witchweed. Field trials were conducted in four locations in Nigeria in 2007 and 2008, to assess the effect of coating seeds of several maize hybrids with imazapyr on witchweed control. The hybrids had genes for imidazolinone herbicide resistance ... -
Popular biofortified cassava cultivars are heavily impacted by plant parasitic nematodes, especially Meloidogyne Spp.
(2020)The development of new biofortified cassava cultivars, with higher micronutrient contents, offers great potential to enhance food and nutrition security prospects. Among the various constraints affecting cassava production are plant parasitic nematodes (PPN), especially root-knot nematodes. In this study, six popular biofortified cultivars were field-evaluated for their response to PPN in Nigeria. A field naturally infested with a diversity of PPN but dominated by root-knot nematodes was used. ... -
Seed yam production from whole tubers versus minisetts
(2020)Yam (Dioscorea rotundata Poir.) is a major staple and cash crop for millions of households in West Africa, where about 93% of the world crop is produced. The tuber serves as food and seed. Depending on the size, seed tubers are often cut into setts, minisetts, or planted whole. An experiment was conducted to investigate the effects of using whole tubers versus minisetts to produce seed yams. Six treatments constituted combinations of whole tubers and minisetts, and three tuber-size classes, viz., ... -
Making smallholder value chain partnerships inclusive: exploring digital farm monitoring through farmer friendly smartphone platforms
(2020)Value chain partnerships face difficulties achieving inclusive relations, often leading to unsustainable collaboration. Improving information flow between actors has been argued to contribute positively to a sense of inclusion in such partnership arrangements. Smallholders however usually lack the capability to use advanced communication technologies such as smartphones which offer a means for elaborate forms of information exchange. This study explores to what extent co-designing smartphone ...