Journal and Journal Articles: Recent submissions

Now showing items 1881-1900 of 5157

    • Agricultural soils as a sink to mitigate CO2 emissions 

      Paustian, K.; Andren, O.; Janzen, H.H.; Lal, R.; Smith, P.; Tian, G.; Tiessen, H.; Noordwijk, M. van; Woomer, P.L. (1997)
      Agricultural soils, having been depleted of much of their native carbon stocks, have a significant CO2 sink capacity. Global estimates of this sink capacity are in the order of 20-30 Pg C over the next 50-100 years .Management practices to build up soil C must increase the input of organic matter to soil and/or decrease soil organic matter decomposition rates. The most appropriate management practices to increase soil C vary regionally dependent on both environmental and socioeconomic factors

    • Protein quality of raw and autoclaved cowpeas: Comparison between some insect resistant and susceptible varieties 

      Umoren, U.E.; Tewe, O.O.; Bokanga, M.; Jackai, L.E.N. (1997)
      A comparative study was conducted with four improved cowpea (2 pod bug resistant and 2 susceptible) varieties to assess the effect of autoclaving at 105 ~ under 15 psi for 30 min on their protein quality, as measured by the levels of some antinutritional factors and performance of rats fed the different cowpea diets. Also, the relationships between antinutrients in the cowpeas and protein quality indicators were examined. Results showed that autoclaving completely eliminated trypsin inhibitor, ...

    • Variability in susceptibility to simulated sunlight of conidia among isolates of entomopathogenic hyphomycetes 

      Fargues, J.; Goettel, M.S.; Smits, N.; Ouédraogo, A.; Vidal, C.; Lacey, L.A.; Lomer, C.J.; Rougier, M. (1997)
      The influence of simulated sunlight on survival of conidia of 4 species of entomopathogenic Hyphomycetes was investigated. Conidia from 65 isolates ofBeauveria bassiana, 23 ofMetarhizium anisopliae, 14 of Metarhizium flavoviride and 33 isolates of Paecilomycesfumosoroseus were irradiated by artificial sunlight (295 to 1,100 nm at an ultraviolet-B irradiance of 0.3 W m -2) for 0, 1, 2, 4 and 8 h. Survival was estimated by comparing the number of colony forming units (CFU) produced by conidia exposed ...

    • Exchanging natural enemies species of lepidopterous cereal stemborers between African regions 

      Schulthess, F.; Bosque-Pérez, N.A.; Chabi-Olaye, A.; Gounou, S.; Ndemah, R.; Goergen, Georg E. (1997)
      Difficulties of identification of natural enemies of cereal stemborers for 'redistribution' in Africa are discussed. Tritrophic level studies on wild and cultivated habitats of borers and beneficial species are needed to judge the impact of a natural enemy species in the cropping system. Areas witli low Pest pressure which are climatically favorable for Pest development may be selected for study. Based on the results of various countrywide surveys to map the relative importance of Sesaniia calnmistis ...

    • Host response to black sigatoka in Musa germplasm of different ages under natural inoculation conditions 

      Mobambo, K.N.; Pasberg-Gauhl, C.; Gauhl, F.; Zuofa, K. (1997)
      The development of an early evaluation method for host response of different Musa clones to black sigatoka was investigated under natural inoculation conditions in southeastern Nigeria. Two months old tissue-culture-derived plants of three plantain hybrids and parents of the hybrids were exposed to the natural inoculum of Mycosphaerella fijiensis in a field planted with a susceptible plantain cultivar. The response to M. fijiensis was evaluated on these young plants and on the same clones of mature, ...

    • Cassava based intercropping: a review 

      Mutsaers, H.; Ezumah, H.; Osiru, D. (1993)
      This paper reviews intercropping research for a particular case: cassava-based crop combinations. Cassava is dominated in combination with maize while it is the dominating species in combination with low-growing species. Combinations with maize or legumes show a real biological advantage over the sole crops reflected in (modified) Area × Time Equivalency ratio (ATER) values above unity. This is not the case with sweet potatoes. Success of maize+cassava mixtures depends on time and rate of recovery ...

    • Banana weevil, Cosmopolites sordidus Germar (Coleoptera, Curculionidae) infestation of cooking and beer bananas in adjacent stands in Uganda 

      Gold, C.S.; Bagabe, M.I. (1997)
      Banana-weevil populations and associated damage were studied in adjacent plantations of highland cooking-bananas (cultivar Kibuzi) and introduced beer-bananas (cv. Kisubi) on a farm in central Uganda. Weevil density and mobility were assessed using mark and rerapture techniques. Residual banana corms and pseudostems were evaluated for weevil damage at various intervals following harvest. Newly harvested cooking-bananas revealed moderate weevil damage that reached the corm centre, whereas damage ...

    • Multivariate pattern of quantitative trait variation in triploid banana and plantain cultivars 

      Osuji, J.O.; Okoli, B.E.; Vuylsteke, D.; Ortiz, R. (1997)
      Plantains and bananas (Musa spp. L.) are inter- or intraspecific triploid hybrids derived from crosses between M. acuminata Colla. (A genome) and M. balbisiana Colla. (B genome). Cultivars have been assigned to different taxonomic groups (AA, BB, AAA, AAB, ABB, etc.) based on morphological qualitative descriptors. Principal component analysis of 15 quantitative traits was carried out to establish a more objective taxonomic relationship of cultivar groups and subgroups in the Musa germplasm. Fruit ...

    • Development of Metarhizium spp. for the control of locusts and grasshoppers 

      Lomer, C.J.; Prior, C.; Kooyman, C. (1997)
      Four research programmes are investigating the entomopathogenic fungal genera Metarhizium and Beauveria for locust and grasshopper control in Africa. In the LUBILOSA programme, surveys for pathogen isolates revealed a morphologically distinctive Metarhizium flavoviride Gams and Rozsypal attacking acridoids in West Africa, Madagascar, and elsewhere. Metarhizium anisopliae (Metschnikoff) Sorokin isolates with virulence to acridoids were also obtained, including several from non-orthopteran hosts. ...

    • Silicon disease resistance, and yield of rice genotypes under upland cultural conditions 

      Winslow, M. (1992)
      Silicon deficiency limits rice (Oryza sativa L.) yield on highly weathered upland soils in West Africa and can increase susceptibility to some diseases. A study at Onne, Nigeria, examined responses of different genotypes to increasing Si supply under upland cultural conditions. Without applied Si, average shoot Si concentration was one-fifth of the minimum recommended value for rice, confirming deficiency. Application of 18.7 g Si m−2 as sodium metasilicate doubled plant Si concentration and ...

    • Agricultural intensification, soil biodiversity and agroecosystem function in the tropics: the role of decomposer biota 

      Beare, M.H.; Reddy, M.V.; Tian, G.; Srivastava, S.C. (1997)
      Intensification of agriculture in the tropics has resulted from a shortage of farmland and insufficient food production to satisfy the needs of an expanding population. Many tropical farmers are challenged by the prospect of intensifying their production while sustaining or improving the fertility and productivity of soils with only locally available natural resources. The waste products of plant and animal production represent some of the most abundant natural resources available for use by ...

    • Farmers perception of constraints in plantain production in Ghana 

      Schill, P.F.; Afreh-Nuamah, K.; Gold, C.S.; Green, K.R. (2000)
      Plantain (Musa AAB), a primary food crop in Ghana, is a key component in sustainable agricultural systems in high rainfall zones. Recently, there has been a substantial yield decline and reduction in plantation life. To elucidate the context in which intervention strategies should be developed, a Participatory Rural Appraisal (PRA) was conducted at five villages in the major plantain-producing belt of Ghana. The importance of plantain as a preferred food was confirmed, although farmers tended to ...

    • ALSinhibiting herbicide seed treatments control Striga hermonthica in ALSmodified corn (zea mays) 

      Berner, D.K.; Ikie, F.O.; Green, J.M. (1997)
      Seed treatments with two acetolactate synthase (ALS)-inhibiting herbicides, the sulfony- lurea herbicide nicosulfuron and the imidazolinone herbicide imazaquin, controlled the parasitic weed Striga hermonthica in corn. The XA-17 gene in ALS-modified P3180IR corn strongly reduced corn injury from herbicide seed treatments while another ALS modification was not effective. Combining seed treatment of ALS-inhibiting herbicides and ALS-modified corn with the XA-17 gene may offer a practical means for ...

    • Influence of pruning frequency of Albizia lebbeck, Gliricidia sepium and Leucaena leucocephala on nodulation and potential nitrogen fixation 

      Kadiata, B.D.; Mulongoy , K.; Isirimah, N.O. (1997)
      The influence of four pruning frequencies on biomass, nodulation and N2 fixation was investigated on Albizia lebbeck, Gliricidia sepium and Leucaena leucocephala grown in the screenhouse for 16 months, using acetylene reduction and 15N dilution methods. Frequent prunings at 4-month intervals had no deleterious effect on symbiotic N2 fixation, which increased in Gliricidia and Leucaena in particular. Nodulation and nitrogenase activity varied inconsistently within species, and were not influenced ...

    • Amelioration of a degraded Oxic Paleustalf by leguminous and natural fallows 

      Kang, B.T.; Salako, F.K.; Akobundu, I.O.; Pleysier, J.L.; Chianu, J.N. (1997)
      The restorative ability of herbaceous (Psophocarpus palustris, Pueraria phaseoloides) and woody (Leucaena leucocephala, Senna siamea, Acacia leptocarpa, Acacia auriculiformis) legume species and of natural regrowth was studied on an eroded and compacted Oxic Paleustalf in southwestern Nigeria. Compared to the control treatment that was continuously cropped for 15 years, four years of fallowing significantly improved test crop yields. However, fallowing with the above species did not substantially ...

    • Effects of cassava pubescene on the behaviour, postembryonic development and reproduction of the cassava mealybug, Phenacoccus manihoti matileferrero (Homoptera: pseudococcidae) 

      Kasu, T.; Odebiyi, J.; Lema, K. (1989)
      Role of trichome density in cassava resistance to mealybug, Phenacoccus manihoti Matile-Ferrero was evaluated on the apex, the first expanded leaf and the stem in pubescent and glabrous cassava varieties. Pubescence significantly retarded the rate of settling and establishment of P. manihoti. The weight of the developing larvae was also affected becoming more pronounced at the pre-ovipositing adult stage. However, the relationship between pubescence and P. manihoti weight was not significant. ...

    • Institutionalizing the farming systems perspective in multicommodity research institute: the role of systemsbased research groups 

      Spencer, D. (1991)
      Research institutes in Africa have had limited success in producing new technologies appropriate to the needs of small farmers because of an inadequate understanding of small farmers' goals and resource limitations and over-reliance on the transfer of technologies from other regions. Farming systems research (FSR) is an effective way of improving the focus of scientists on the problems farmers face. Vertically segmented thematic research programmes make institutionalization of FSR difficult within ...

    • First report and pathogenicity of Myrothecium roridum, Curvularia eragrostidis and C.lunata on seeds of Striga hermonthica in Nigeria 

      Czerwenka-Wenkstetten, I.M.; Berner, D.K.; Schilder, A.; Gretzmacher, R. (1997)
      Striga is a weed known to be devastating to crops in the tropics. Yield reductions in maize of up to 90% have been observed in West Africa. In September 1994, a seed lot of Striga hermonthica (harvested in 1993 in sorghum fields in Abuja, Nigeria) was observed to have a very low germination rate (20 to 40%). Single-spore isolates from fungal colonies growing on the striga seeds were identified as Myrothecium roridum, Curvularia eragrostidis, and C. lunata. Pathogenicity to striga was tested. Striga ...

    • Soil improvement by trees in sub-Saharan Africa 

      Buresh, R.J.; Tian, G. (1997)
      Trees can influence both the supply and availability of nutrients in the soil. Trees increase the supply of nutrients within the rooting zone of crops through (1) input of N by biological N2 fixation, (2) retrieval of nutrients from below the rooting zone of crops and (3) reduction in nutrient losses from processes such as leaching and erosion. Trees can increase the availability of nutrients through increased release of nutrients from soil organic matter (SOM) and recycled organic residues. Roots ...

    • Effects of rehydration on the conidial viability of Metarhizium flavoviride mycopesticide formulations 

      Moore, D.; Langewald, J.; Obognon, F. (1997)
      The rehydration of dried conidia of Metarhizium flavoviride was investigated in an attempt to increase speed of kill of locusts and grasshoppers by formulations of this fungus. Conidia were dried to 4-5% moisture content with no apparent adverse effects on viability, but rapid rehydration (by putting dried conidia directly in free water) reduced viability. Rehydration in an atmosphere of high humidity allowed dry conidia to absorb sufficient moisture to avoid imbibition damage. Rehydrating and ...