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Journal and Journal Articles: Recent submissions
Now showing items 1781-1800 of 5157
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The mineralization of sulfur from organic residues measured by inverse isotope dilution
(2006)Sulfur (S) deficiency in soils is increasingly recognized in agricultural systems. The quantification of S mineralization/immobilization processes after incorporation of organic materials into soils is a key factor to predict the availability of S to growing plants. However, immobilization and mineralization occur simultaneously making the quantification of the magnitude of each process difficult. We used the inverse isotope (35SO4) dilution technique to quantify immobilization and mineralization ... -
Effects of soil wetness at the time of land clearing on physical properties and crop response on an Ultisol in southern Nigeria
(1992)Land clearing of a tropical rainforest implies cutting and felling of existing vegetation by manual or mechanized techniques, with or without windrowing, followed by burning in situ or in windrows. The objective of this study was to evaluate effects of land clearing at three levels of initial soil wetness on soil physical properties, and on growth and yield of maize and cowpea for a tropical Ultisol in southern Nigeria. One of three main-plot treatments measuring 6 × 40 m was cleared mechanically ... -
Breeding cowpea varieties with combined resistance to Striga gesnerioides and Alectra vogelii
(2000)Two parasitic fl owering plants, Striga gesnerioides (Wild.) Vatke and Alectra vogelii (Benth.), cause substantial yield reduction in cowpea in the dry savannas of sub-Saharan Africa. Alectra is more prevalent in the northern Guinea savanna and southern Sudan savanna of West Africa, as well as in East and southern Africa whereas Striga is mostly found in West and Central Africa. However, both are fast spreading beyond these limits. Collaborative studies with national and regional programs have ... -
Improved cropping systems for higher productivity in the dry savannas of West Africa
(2000)Most of the farmers in the dry savannas of West Africa plant local varieties of cowpea, millet, sorghum, and groundnut in various intercropping systems with little or no purchased inputs. In this system, the cowpea and groundnut yields are low due to shading by cereals and lack of plant protection measures. The cereal yields are low mainly due to lack of fertilizer. Efforts are being made, therefore, to develop a combination of improved varieties and improved cropping systems for higher productivity ... -
Effects of fertilizer and hot water treatment upon establishment, survival and yield of plantain (Musa spp., AAB, French)
(2000)Plantain (Musa spp. AAB, French, cv. Essong) was grown on an acid ultisol in southern Cameroon to determine yield response to (1) a hot-water treatment to control nematodes and (2) the application of fertilizer. Observations were made for 42 months. Establishment was unaffected by hot-water treatment or fertilizer. Hot-water treatment reduced nematode infestation to about 30% of that found in untreated plants and increased rhizome survival by 11%. Fertilizer application increased the proportion ... -
The effects of mulch from selected multipurpose trees on nitrogen nutrition, growth and yield of maize (Zea mays)
(2000)Leaf extracts and mulch from 14 multipurpose trees were used to test their effects on maize germination, growth and yield. Maize germination was significantly reduced by leaf extracts of all species with increasing extract concentration. The most drastic reductions were caused by Gliricidia sepium, Tetrapleura tetraptera, Lonchocarpus sireceus, Senna siamea and Leucaena leucocephala. Terminalia superba, Tetrapleura tetraptera, Pithecelobium dulce, Gliricidia sepium and Senna siamea significantly ... -
The elusive banana weevil Cosmopolites sordidus Germar
(2000)The banana weevil Cosmopolites sordidus Germar, has evaded all efforts to manage it in all banana-based cropping systems except the commercial plantation banana system, where the 2 to 3 year crop cycle and the intensity of management limit the pest survival in that system. Conversely, in backyard and subsistence banana systems, predominant in Africa, the perennial cropping of banana and plantain, coupled with the planting of infested material, readily supports the pest survival strategies, resulting ... -
Bioecology of the cowpea pod weevil Piezotrachelus varius Wagner (Coleoptera: Curculionidae), and cowpea seed damage
(2006)The bioecology of the cowpea pod weevil, Piezotrachelus varius, and post-harvest seed losses were studied in the laboratory and in cowpea fields in the Western Highlands of Cameroon during the first and second cropping seasons of 1999 and 2000. Adult weevils appeared before flowering and fed on cowpea leaves and flowers before switching to newly formed pods. Pod-feeding produced holes on the pod wall mesocarp through which the female layed a cluster of 2-5 ovoid, semi-translucent eggs; the eggs ... -
A cage experiment with four trophic levels: cassava plant growth as influenced by cassava mealybud, Phenacoccus manihoti, its parasitoid Epidinocarsis lopezi,and the hyperparasitoids Prochiloneurus insolitus and Chartocerus hyalipennis
(1992)Different combinations of insects belonging to three trophic levels were released in large cages with hydroponie cultures of cassava in a greenhouse. The cassava mealybug (CM )' Phenacoccus manihoti Matile-Ferrero (Horn., Pseudococcidae) was applied at two initial infestation densities to cassava, some of which was grown at different fertilizer levels. Some cages received Epidinocarsis lopezi (De Santis) (Hym., Encyrtidae), the CM specific parasitoid, and/or the hyperparasitoids Prochiloneurus ... -
Transformations and recovery of residue and fertilizer nitrogen15 in a sandy Lixisol of West Africa
(2000)The fate of 15N-labeled plant residues from different cover-cropping systems and labeled inorganic N fertilizer in the organic, soil mineral, microbial biomass and soil organic matter (SOM) particle-size fractions was investigated in a sandy Lixisol. Plant residues were from mucuna (legume), lablab (legume), imperata (grass), maize (cereal) and mixtures of mucuna or lablab with imperata or maize, applied as a surface mulch. Inorganic N fertilizer was applied as 15N-(NH4)2SO4 at two rates (21 and ... -
Clustering shrub and tree legumes grown in acid and nonacid soil conditions using rank performance data
(2000)Clustering of ten woody and shrub legumes (Acacia auriculiformis, Albizia lebbeck, Gliricidia sepium, Leucaena diversifolia, L. leucocephala var. K28 and var. K636, Lonchocarpus sericeus, Cajanus cajan, Crotalaria juncea and Tephrosia candida) was performed using the partitioning around medoid and the Fuzzy clustering methods to assess the appropriateness of their earlier performance rank scores for evaluating their dissimilarity within an Alfisol and an Ultisol. Differences among formed clusters ... -
Selective control of weeds in an arable crop by mulches from some multipurpose trees in southwestern Nigeria
(2000)The use of agroforestry systems in which pruning from trees is used to mulch the companion crops is an important area of research in the tropics. However, previous studies mostly evaluated the contribution of mulch to soil improvement and rarely examined the effect of mulch on weeds. Field experiments were conducted during the 1995 and 1996 growing seasons to investigate the effects of mulch from three woody fallow species on weed composition, biomass and maize grain yield. Treatments consisted ... -
Symbiotic nitrogen fixation response of Mucuna as affected by rhizobial inoculation in farmers fields in the derived savanna of Benin
(2000)Leguminous cover crops such as Mucuna pruriens (mucuna) have the potential to contribute to soil N and increase the yields of subsequent or associated cereal crops through symbiotic N fixation. It has often been assumed that mucuna will freely nodulate, fix N2 and therefore contribute to soil N. However, results of recent work have indicated mucuna's failure to nodulate in some farmers' fields in the derived savanna in Benin. One of the management practices that can help to improve mucuna establishment ... -
The role of extension services for the successful introduction of new Musa cultivars in southeastern Nigeria
(2000)Black sigatoka (Mycosphaerella fijiensis) causes yield losses of 30 to 50% in banana and plantain. The cultivation of resistant cultivars is the most appropriate intervention to control this fungal leaf spot disease in Africa. The short-term approach of the International Institute of Tropical Agriculture (IITA) to control black sigatoka in Nigeria was to identify, multiply and distribute resistant cooking bananas. The Green River Project (GRP), in collaboration with IITA, has been promoting cooking ... -
Nitrogen contributions from decomposing cover crop residues to maize in a tropical derived savanna
(2000)In cover cropping systems in the tropics with herbaceous legumes, plant residues are expected to supply nitrogen (N) to non-legume crops during decomposition. Field experiments were carried out to (i) determine the effects of residue quality on decomposition and N release patterns of selected plants in cover cropping systems, (ii) relate the pattern of residue N release to N uptake by maize in cover cropping systems. To study decomposition, litter bags were used and monitored over two maize growing ... -
Influence of phytoparasitic nematodes on symbiotic N2 fixation in tropical herbaceous legume cover crops
(2000)Populations of plant parasitic nematodes and their effects on symbiotic nitrogen (N) fixation in herbaceous legumes and on some selected characteristics of other plant species associated with such cover crops were studied. Two legume species [mucuna, Mucuna pruriens (L) DC. var. utilis (Wright) Bruck and lablab, Lablab purpureus L. Sweet], one grass/weed species [imperata, Imperata cylindrica (L.) Rauschel] and a cereal (maize, Zea mays L.) were used. There were three soil treatments (fumigation, ... -
Evaluation of symbiotic dinitrogen inputs of herbaceous legumes into tropical cover crop systems
(2000)Reliable estimates of symbiotically fixed N2 in herbaceous legumes are important in order to determine their role in maintaining or improving N levels in tropical low-external-input farming systems. We have studied the effects of different management systems on the suitability of two non-N2-fixing reference crops, imperata [Imperata cylindrica (L.) Rauescel] and maize (Zea mays L.), for estimating N2 fixation in mucuna [Mucuna pruriens (L.) DC var. utilis (Wright) Bruck] and lablab [Lablab purpureus ... -
Utilization of molecular genetic techniques in support of plantain and banana improvement
(2000)Molecular genetic techniques may have a wide range of applications for improving the efficiency of Musa breeding and conservation. These range from analysis of genetic behaviour and structure, germplasm characterization and marker assisted selection. Restriction fragment length polymorphism (RFLP) appears to have limited application in Musa. Thus, we have concentrated on applications of the polymerase chain reaction (PCR) for Musagenome analysis. Random amplified polymorphic DNA (RAPD) techniques ... -
Comparative analysis of phenotypic and genoytpic diversity among plantain landraces (Musa spp., AAB group)
(2000)Genetic diversity amongst 76 plantain landraces has been studied using RAPD analysis at two levels of intensity and compared with groupings based on phenotypic indices and morphotype. There was a good correlation (R2=0.78) between estimates of genetic diversity based on 76 RAPD bands and 164 RAPD bands. However, there was a poor correlation between RAPD-based estimates of genetic diversity and a phenotypic index based on agronomic characters. There was also a poor correlation between RAPD analyses ...
