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Journal and Journal Articles: Recent submissions
Now showing items 1761-1780 of 5157
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Genetic gains in nordic spring barley breeding (1930searly 1990s)
(2002)Accurate assessments of genetic gains ensuing from plant breeding for the most important agronomic characteristics in Nordic spring barley (Hordeum vulgare L.) are not available. Hence this research was aimed to determine the rate of genetic improvement in the Nordic barley breeding pool. This study included 90, 2-row spring barley cultivars released (1942–1988) and 29, 6-row spring barley cultivars released (1930–1991) adopted by Nordic farmers that were tested in four Nordic locations for three ... -
Spatial analysis of Prostephanus truncatus (Horn) (Coleoptera:Bostrichdae) flight activity near maize stores and in different forest types in southern Benin, West Africa
(2002)Weekly Prostephanus truncatus (Horn) ßight activity, measured as the density of captured beetles in pheromone baited traps, was monitored for 76 consecutive weeks at 16 sites inside the Lama forest in southern Benin and at four sites in maize farmland just outside the forest. Prostephanus truncatus ßight activity was consistently higher and the ßight activity pattern signiÞcantly different near maize stores than at sites inside the forest. Although P. truncatus is known to infest girdled branches ... -
Hierarchical and factorial mating designs in quantitative genetics of tetrasomic potato
(2002)Plant breeders need to quantify additive and non-additive components of genetic variance in order to determine appropriate selection methods to improve quantitative characteristics. Hierarchical and factorial mating designs (also known as North Carolina mating designs I and II, respectively) allow one to determine these variance components. The relative advantages of these two designs in the quantitative genetics of tuber yield in tetrasomic potato were investigated. Likewise, the number of female ... -
Influence of cereal legume rotation on soil chemical properties, crop yield and Striga control
(2006)Integrated soil management with grain legumes was studied at two villages (Ugwan Shamaki) and Tashan Kaya) in Kaduna State, northern Guinea Savanna zone of Nigeria (190 day growing season). Impacts of one year rotation of Soybean and Cowpea on soil chemical properties were compared with sole maize and maize-cowpea mixture. All plots were Striga infested. Organic carbon decreased by 4 and 2% in maize after maize (SM) plots in Ugwan Shamaki and Tashan Kaya respectively. Sole soybean, SC and MC mixture ... -
Natural enemies of the maize cob borer Mussidia nigrivenella (Lepidoptera: Pyralidae) in Benin, West Africa
(2002)Mussidia nigrivenella Ragonot is a pest of maize cobs in West Africa. It significantly reduces maize yields and grain quality, with quantitative losses of 2–25% at harvest, and up to 10–15% indirect losses due to an increase in storage pest infestation levels. Infestation by M. nigrivenella also significantly increased the susceptibility of maize to Aspergillus flavus infection and subsequent aflatoxin contamination. Surveys conducted in different agro-ecological zones of Benin on cultivated and ... -
Geographical patterns of diversity for morphological and agronomic traits in the groundnut germplasm collection
(2002)The characterization of diversity in germplasm collection is important to plant breeders to utilize and to the genebank curators to manage the collection efficiently and effectively. The objective of our study was to describe the phenotypic diversity in the 13342 accessions of groundnut (Arachis hypogaea L.) germplasm contained in the ICRISAT genebank. The germplasm accessions were characteized for 16 morphological descriptors, 10 agronomic traits in two seasons, and for reaction to early leaf ... -
Effect of water management and polyolefin-coated urea on growth and nitrogen uptake of indica rice
(2002)Poor water management and high nitrogen (N) losses are the key problems faced by rice farmers under rainfed inland valley systems. There is a need to evaluate different N fertilizers so as to identify one that could withstand these problems. The performance of polyolefin-coated urea (POCU) was therefore compared with conventional urea in a pot experiment with indica rice (Oryza sativa L. cv. IR36), using two water management systems: 1) Submerged condition referred to as good water management ... -
Development and deployment of transgenic plants: biosafety considerations
(2002)Recombinant DNA technology has great potential to enhance and extend the advantages of conventional plant breeding, and increase the production and productivity of crops to meet the increasing demand for food and food products in the future. Judicious application of this technology provides opportunities for alleviating some of the major constraints to crop productivity under subsistence farming conditions in the developing countries. Considerable progress has been made in developing strategies ... -
Ploidy analysis in water yam, Dioscorea alata L., germplasm
(2002)Poor reproductive development in yams (Dioscorea spp.) has often been attributed to the polyploid nature of the crop. In this study, flow cytometry was used to determine the ploidy level of 53 accessions of Dioscorea alata, mostly from West African countries, Chad and Puerto Rico. Nuclei were isolated from young leaf material and stained with DAPI (4,6-diamidino-2-phenylindole). The nuclear genome size (2C) was measured as an indicator of the ploidy level. Dioscorea rotundata genotypes with known ... -
Effects of legume intercrops on soilborne pests, biomass, nutrients, and soil water in banana
(2002)Banana (Musa AAA) and plantain (Musa AAB) are important dietary staples for over 70 million people in sub-Saharan Africa. Banana weevil (Cosmopolites sordidus) and nematodes (Radopholus similis, Helicotylenchus multicinctus) are often the largest constraints to production. Leguminous crops in the genera Canavalia, Mucuna and Tephrosia have been reported as having repellent or insecticidal properties. We assessed: weevil and nematode populations and damage; banana growth and development; soil and ... -
Factors affecting plant disease suppression by biocontrol: a meta analysis
(2006)Studies to evaluate the effectiveness of biological control in suppressing plant disease often report inconsistent results, highlighting the need to identify general factors that influence the success or failure of biological control in plant pathology. We conducted a quantitative synthesis of previously published research by applying meta-analysis to determine the overall effectiveness of bio-control in relation to biological and application-oriented factors. For each of 149 entries (antagonist–disease ... -
A genetic linkage map of water yam (Dioscorea alata L.) based on AFLP markers and QTL analysis for anthracnose resistance
(2002)A genetic linkage map of the tetraploid water yam (Dioscorea alata L.) genome was constructed based on 469 co-dominantly scored amplified fragment length polymorphism (AFLP) markers segregating in an intraspecific F1 cross. The F1 was obtained by crossing two improved breeding lines, TDa 95/00328 as female parent and TDa 87/01091 as male parent. Since the mapping population was an F1 cross between presumed heterozygous parents, marker segregation data from both parents were initially split into ... -
In vitro, greenhouse, and field assessment of cassava lines for resistance to anthracnose disease caused by colletotrichum gloeosporiodes f. sp. Manihotis
(2002)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 ... -
Genotypic variation for root pulling resistance in potato and its relationship with yield under water deficit stress
(1992)An extensively distributed root system may reduce the probability of crop failure during periods of restricted water supply . A quantitative measure of root distribution in the soil profile, i .e . pulling resistance of roots (PR), was tested at two moderately droughted tropical field sites . A total of 250 genotypes were evaluated for PR, 45 days after planting and for tuber yield at harvest at separate sites and years . The need to use genotypes adapted to a specific location for comparisons, ... -
Low prevalence of ataxic polyneuropathy in a community with high exposure to cyanide from cassava foods
(2002)Ataxic polyneuropathy, which occurs in endemic form in an area in southwest Nigeria, is attributed to exposure to cyanide from cassava foods. Exposure to cyanide from cassava is, however, not exclusive to this endemic area. In this study, the occurrence of ataxic polyneuropathy was compared in two communities in Nigeria, one located in the endemic area and the other located outside the endemic area. Both communities have been shown to have high exposure to cyanide from cassava foods. The prevalence ... -
Morphological and isozymic diversity of the cultivated yams (Dioscorea cayenensis/Dioscorea rotundata complex) of Cameroon
(2002)Using IPGRI's descriptors, 45 accessions of Guinea yams (Dioscorea cayenensis Lam./ Dioscorea rotundata Poir. complex) collected in Cameroon were classified into six cultivar groups based on their morphological similarities. An identification key is proposed for the cultivar groups. Six enzymatic systems (6PGD, PGI, AAT, SKDH, PGM, EST) were also used to assess genetic variation within these cultivated yams. Twenty-eight genotypes were identified within the 45 accessions analysed. The clustering ... -
Optimum sample size for determining disease severity and defoliation associated with Septoria leaf spot of blueberry
(2006)In a 3-year field study, Premier rabbiteye blueberry plants were sampled at three hierarchical levels (leaf, shoot, and bush) to assess severity of Septoria leaf spot (caused by Septoria al- bopunctata) and incidence of defoliation. A positive linear relationship (R2= 0.977, P< 0.0001, n = 2127) was observed between the number of spots per leaf and percent necrotic leaf area, both assessed on individual leaves in mid- to late October. For data summarized at the shoot level, percent defoliation ...
