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Journal and Journal Articles: Recent submissions
Now showing items 1741-1760 of 5157
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Selection of rhizobacterial strains for suppression of germination of Striga hermonthica (Del.) Benth. seeds
(2002)Striga hermonthica (Del.) Benth. is an obligate root-parasitic flowering plant that severely threatens cereal production in sub-Saharan Africa. A potential biological control option for reduction of crop yield–loss within the season of application is the use of soil-borne antagonists of S. hermonthica seed. This study was aimed at selecting soil-borne fluorescent pseudomonad strains capable of suppressing germination of S. hermonthica seeds and consequently reducing parasitism and damage to maize. ... -
Analysis of phenotypic stability in ten cassava genotypes in three West African countries
(2002)Ten Cassava (Manihot esculenta, Crantz) genotypes were assessed for phenotypic fresh tuber yield stability for 2 years in nine locations in three West African countries (Nigeria, Ghana and Benin). From a combined analysis of variance for fresh yield, all main effects were significant. First order interaction genotype x year was not significant, while genotype and location interaction was significant. By Finlay and Wilkinson'sb-values tability statistic 82/00058 was considered highly yielding with ... -
Profitability of cassava-maize production under different fallow systems and land-use intensities in the derived savanna of southwest Nigeria
(2002)Population pressure has diminished the role of the traditional bush fallow system in restoring the fertility of depleted soils following several years of cultivation in the derived savanna of southwest Nigeria. The search for alternative fallow systems led to the development of alley cropping using Leucaena leucocephala and cover cropping using Pueraria phaseoloides. These soil-conserving systems also embody the principles of sustainability by ensuring stable crop yields in spite of an increase ... -
Optimal sampling strategy and core collection size of Andean tetraploid potato based on isozyme data: a simulation study
(2002)Selection of an appropriate sampling strategy is an important prerequisite to establish core collections of appropriate size in order to adequately represent the genetic spectrum and maximally capture the genetic diversity in available crop collections. We developed a simulation approach to identify an optimal sampling strategy and core-collection size, using isozyme data from a CIP germplasm collection on an Andean tetraploid potato. Five sampling strategies, constant (C), proportional (P), ... -
Diversity changes in an intensively bred wheat germplasm during the 20th Century
(2002)Plant breeding may lead to narrowing genetic diversity of cultivated crops, thereby affecting sustained selection gains in crop improvement. A total of 47 microsatellite primer pairs (mapped to the 21 wheat genetic linkage groups) were assessed in 75 Nordic spring wheat cultivars bred during the 20th century to determine the variation of genetic diversity in this germplasm throughout this period. The number of alleles ranged from one to seven, with an average of 3.6 alleles per microsatellite ... -
Wet-cold preservation of West African yam (Dioscorea spp.) pollen
(2002)Hermetic cold storage without previous drying (wet–cold storage) was experimented for the preservation of yam pollen grains. Pollens collected from white yam D. rotundata and a wild relative, D. praehensilis, were stored at -80, -20, 5, and 150C in sealed packs for 2 years. Pollen samples were drawn for in vitro germination tests after 100 and 700 days, and hand pollination was conducted after 365 and 730 days in storage. Pollen germination responses were not significantly different among the two ... -
Heritability studies of some cassava genotypes
(2002)Three traits, namely root number (RTNO), root weight(RTWT) and fresh yield (FYLD) of some cassava genotypes wrer scored and analysed for heritability. The genotypes differed significantly for each of the tree traits. Generally heritability per replicate was above 50% indicating that the additive portion of the genetic variance might be high. Heritability per plot ranged between 69% and 86% which might indicate that non additive effect of the genotypic variance variance might be small. Phenotypic ... -
Diversity, distribution and farmer preferences of Musa cultivars in Uganda
(2002)The East African highlands, home to more than 80 cultivated varieties of locally evolved bananas, constitute a secondary centre of banana diversity. Uganda is the leading producer and consumer of banana in the region and also enjoys the highest diversity of a group of bananas uniquely adapted to this region. These East African highland bananas comprise cooking and brewing types. The former is a staple for more than 7 million people and thus important for food security. Little is known about the ... -
Prey-related odor preference of the predatory mites Typhlodromalus manihoti and Typhlodromalus aripo (Acari: Phytoseiidae)
(2002)Typhlodromalus manihoti and Typhlodromalus aripo are exotic predators of the cassava green mite Mononychellus tanajoa in Africa. In an earlier paper, we showed that the two predators were attracted to odors from M. tanajoa-infested cassava leaves. In addition to the key prey species, M. tanajoa, two alternative prey mite species, Oligonychus gossypii and Tetranychus urticae also occur in the cassava agroecosystem. Here, we used a Y-tube olfactometer to determine the attraction of the predators to ... -
Influence of crop management practices in two locations on plantain response to plant parasitic nematodes
(2006)Mulch supported more vigorous plants and repressed nematode activity. Plant parasitic nematodes were responsible for damage to the roots of plantain cv. Agbagba, resulting in reduction in the number of functional leaves on the plants. Inoculated plants had better suckering than the uninnoculated ones when mulched, suggesting that the cumulative effect may result in heavier toppling in the inoculated plots during later growth stage, especially at flowering and fruit filling when the roots of the ... -
Selection criteria of Musa cultivars as determined through a farmer participatory appraisal survey in Uganda
(2002)New varieties are often developed on research stations with limited farmer involvement until the final stages of testing. Recently, farmer participatory approaches have been employed to include farmers' input into breeding objectives at much earlier stages of varietal development. This paper reports on a farmer survey in Uganda to record farmer selection criteria for banana cultivars as a pre-breeding activity. From ranked data, bunch size and crop maturation time were the key selection criteria ... -
Flexible antipredator behavior in herbivorous mites through vertical migration in a plant
(2002)When predation risk varies in space and time and with predator species, successful prey defence requires specific responses to each predator. In cassava fields in Africa, the herbivorous cassava green mite (Mononychellus tanajoa) is attacked by three predatory mite species that are segregated within the plant: the leaf-dwelling Typhlodromalus manihoti and Euseius fustis occur on the middle leaves, whereas the apex-inhabiting T. aripo migrates from the apex to the top leaves only during the night. ... -
Pattern analysis of sorghum genotype x environment interaction for leaf, panicle, and grain anthracnose in Mali
(2002)Resistance to anthracnose, caused by Colletotrichum graminicola, in sorghum was identified through field screening at two locations (Samanko and Longorola) in Mali. The occurrence and progress of anthracnose were monitored on 19 sorghum lines plus resistant and susceptible checks in the 1996 to 1998 rainy seasons. Foliar anthracnose severity was assessed at regular intervals throughout the season. Area under the disease progress curve (AUDPC) was calculated for each genotype. Anthracnose severity ... -
Stomatal response of some cultivated and wild tuberbearing potatoes in warm tropics as influenced by water deficit stress
(1992)Leaf resistances of 14 cultivated potato genotypes ( Solanum spp.) and three tuber-bearing wild Solanum species were compared when plants were grown under water stress at two tropical sites. Factors investigated were diurnal changes in leaf resistance, the effect of plant age, transient drought versus well-watered conditions of potted and field-grown plants. These measurements were carried out in order to determine the stomatal behaviour of tuber-bearing genotypes and species. Significant genotypic ... -
Les insectes et le Sillon Dahomeen: fragmentation et refuges forestiers
(2002)South Eastern Ghana and the south of Togo and Benin constitute a biogeographically remarkable area, called the Dahomey Gap, whose entomological fauna is stilliittie known despite its unique features. The geographical barrier separating this region from the two forest blocks with wetter climates, in the east and the west, is more strongly marked in Ghana th an in Benin, where relict forests still exist. They sustain an in sect fauna belonging to either the western or eastern forest block, with few ... -
Identification and potential application of RAPD markers for anthracnose resistance in water yam (Dioscorea alata)
(2002)Anthracnose, caused by Colletotrichum gloeosporioides, is the most severe foliar disease of water yam (Dioscorea alata) worldwide. The tetraploid breeding line, TDa 95/00328, is a source of dominant genetic resistance to the moderately virulent fast growing salmon (FGS) strain of C. gloeosporioides.Bulked segregant analysis was used to search for random amplified polymorphic DNA (RAPD) markers linked to anthracnose resistance in F1 progeny derived from a cross between TDa 95/00328 and the susceptible ... -
Identification and potential use of RAPD markers linked to yam mosaic virus resistance in white yam (Dioscorea rotundata)
(2002)Resistance to Yam mosaic virus (YMV) in tetraploid white yam (Dioscorea rotundata) is inherited differentially as a dominant and recessive character. Elite D. rotundata breeding lines with durable resistance to YMV can be developed by pyramiding major dominant and recessive genes using marker assisted selection (MAS). The tetraploid breeding line, TDr 89/01444, is a source of dominant genetic resistance to yam mosaic disease. Bulked segregant analysis was used to search for random amplified ... -
Relationships between leaf trichome characteristics and field resistance to cassava green mite (Mononychellus tanajoa (Bondar)
(2002)Experiments were conducted at Ibadan, Nigeria to assess the effect of leaf trichome characteristics (pubescence intensity index, length, and orientation) on field resistance of cassava to the green spider mite, Mononychellus tanajoa (Bondar). There were significant (P < 0.01) differences in M. tanajoa density, damage score and leaf trichome characteristics among the cultivars. During the dry season (February, 1993 and 1994) and the early part of the rainy season (May, 1993), there were significant ... -
Population dynamics of cassava green mite, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae) as influenced by varietal resistance
(2002)The population dynamics of Mononychellus tanajoa as influenced by varietal resistance of cassava was determined over two cassava planting seasons (dry and wet season), using biweekly samples from 11 cassava genotypes in Ibadan, Nigeria. The population size of M. tanajoa and the damage scores were higher during dry than wet season. In 1993, there was a higher mite population and damage peak in January than in March, while in 1994, the peak occurred only in April. Mite population and damage generally ... -
Septoria leaf spot reduces flower bud number and return yield in southern blue berries
(2006)In field trials on Premier rabbit eye blueberry, individual shoots were selected and tagged in the fall of 2001, 2002, and 2003 to quantify the effects of Septoria leaf spot severity and disease-induced premature defoliation on flower bud set and return yield. Experiments were carried out similarly on Blue crisp southern high bush blueberry using shoots tagged after fruit harvest in the summer of 2002 and 2003. Leaves on the distal 20-cm segments of these shoots were monitored for disease severity ...
