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Conference Documents: Recent submissions
Now showing items 141-160 of 597
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Influence of a complex disease involving Praylenchus goodeyi and a nonpathogenic strain of Fusarium oxysporum on banana root health
(1994)Studies were undertaken to determine disease interactions involving P. goodeyi and a non-pathogenic strain of F. oxysporum, both responsible for root-rotting and subsequent toppling of 2 banana cultivars in Kenya. Thirty days after inoculation of young banana plants with P. goodeyi alone or in combination with F. oxysporum the higher density of P. goodeyi was found in necrotic primary roots of the cultivar Nakyetengu (AAA). In primary roots of the cultivar Sukali Ndizi (AB) high density of P. ... -
Intercrop yields of cassava and rice as influenced by cassava variety and population
(1994)The cassava variety and population, which when intercropped with rice leads to increased productivity of the system were identified. Two cassava varieties (Cocoa, a local variety; and 80/40, an improved one) were each planted at four populations (6 666, 10 000, 13 333, and 16 666) as sole crops or intercropped with the rice variety Rok 16. Variety 80/40 significantly out yielded Cocoa (17.2 and 4.1 t/ha, respectively). There was no significant difference in yield between sole and intercropped ... -
Effect of extracts from nine plant species found in Africa on the mycelial growth of Aspergillus flavus Link
(1994)Farmer survey conducted in 1991 and 1992 revealed that some farmer's combat storage moulds using locally available plants. Extracts and combination of extracts of nine different plant species that are used as traditional medicines and aromatic spices in Nigeria were tested for the effect in vitro on the growth of Aspergillus flavus. Aqueous extracts from the combination of dried fruits of xylopia aethiopica and dried seeds of piper guineense completely inhibited the growth of the fungus. Dried ... -
Cassava based foods: how safe are they?
(1994)Cassava production in Africa has increased by 12.5% between 1988 and 1990 with Nigeria becoming the largest cassava producer in the world. Almost all of the African cassava production is destined for human consumption. The consumption of cassava is sometimes associated with toxicity due to its cyanogenic potential (CNP). This paper presents the results of a preliminary survey of the CNP of cassava foods consumed in Kumasi, Ghana. The traditional processing of cassava in Africa and its potential ... -
Post transcriptional silencing of reporter transgenes in tobacco correlates whit DNA methylation
(1994)Endogenous plant genes or transgenes can be silenced on introduction of homologous gene sequences. Here we document a reporter gene-silencing event in Nicotiana tabacum that has a distinctive combination of features--i.e., (i) silencing occurs by a posttranscriptional process, (ii) silencing correlates with DNA methylation, and (iii) this de novo methylation is not restricted to cytosines located in the symmetrical motifs CG and CXG. -
Breeding for Striga hemonthica tolerant openpollinated maize varieties in Africa
(1994)A parasitic weed, Striga hermonthica (Del.) Benth., infects millions of hectares of arable land in sub-Saharan Africa, and it threatens production of cereal crops. The objectives of this study were to investigate inheritance in maize (Zea mays L.) inbred lines of tolerance and resistance to S. hermonthica, based on visible host plant symptoms and Striga emergence counts. A diallel cross involving 10 inbreds was tested under Striga infested fields at Mokwa, Nigeria, for 5 yr. Host plant response ... -
Determination of optimum sett size for white guinea yam (Dioscorea rotundata Poir.) seed yam production: trends in sprouting in the presprout nursery and field performance
(1994)Six weight-classes of white guinea yam (Dioscòrea rotundata Poir.) setts—2–5, 5.01–10, 10.01–20, 20.01–30, 30.01–40, and 40.01–50 g—were presprouted in fresh, moist sawdust in open-air, propagation beds. The 2–5 g and 5.01–10 g classes were described as microsetts. Three natural groups patterned along the various phases of the sigmoid curve, within which the classes did not perform differently were evident at 26 days after planting (DAP), for sets at the leafy-and leafless-shoots stage. The group ... -
A regional experiment to test green manure cover crops and evaluate the role of Internet based networking
(2000)Land degradation in the West African subregion is threatening the food security and livelihoods of both rural and urban populations. Green manure cover crops have the potential of reversing such trends. A wide range of stakeholders have been involved in the promotion of these technologies and it became apparent that a network was needed to provide a common forum where these cover crop enthusiasts could discuss their problems and identify opportunities for synergy. With the advancement of ICT ... -
An approach for the evaluation of herbaceous legumes with multiple benefits
(2000)In order to promote the identification of herbaceous legumes that may contribute to weed control, soil fertility, crop production, and livestock enterprises, as a means of encouraging sustainable agricultural practices amongst resource-poor farmers, an evaluation method using a simple sampling approach is described. To illustrate the method, result from one experiment in the derived savanna of Nigeria conducted over a period of 2.5 years are presented. The experiment included 14 accessions of ... -
Detection of mislabeled germplasm in cocoa collections using DNA fingerprinting with SSR markers
(2006)Incorrect labeling of cocoa accessions is a significant that has hindered the efficient conservation and use of cocoa germplasm. The United States Department of Agriculture (USDA), together with the international collaborating institutions, has undertaken a program to identify the cocoa genotypes and describe the genetic diversity in the major international and national cocoa collections maintained in the Americas. To date, a total of 4027 coca accessions maintained in the two international genebanks ... -
Suitability of Pueraria phaseoloides, Chromoleana odorata and Tithonia diversifolia for nematode management in Musa cropping systems
(2006)Mulching with plant organic matter has been shown to reduce nematode population densities in various cropping systems. The level of nematode control is increased when such mulches are incorporated into the soil as organic amendments. Chromolaena odorata, Tithonia diversifolia and Pueraria phaseoloides are common cover crops in West and Central Africa that produce large quantities of nutrient rich biomass. The aim of this study was to determine, if in-situ mulching of C. odorata, T. diversifolia ... -
Estimation of symbiotically fixed nitrogen using extended N difference methods
(1992)There are limitation to all methods currently available for estimating symbiotically fixed nitrogen. This paper evaluates the I5N dilution and N difference methods, and reports on the results of field experiments conducted with faba beans (Viciafaha) and peas (Pisum sativum). The objectives of these experiments were to investigate whether the limitations of the N difference method, hitherto the least-used method, could be overcome, to study the effect of extending the simple N difference method, ... -
Amelioration of a highly degraded tropical alfisol by planting 1. Changes in soil physical and chemical properties
(1992)This paper examines soil amelioration by planting 15 leguminous and graminaceous plant species, including herbaceous annuals, perennials and biennials, and woody perennials and biennials. Disturbed and undisturbed natural regrowth were planted with leguminous species, in some cases with fertilizer applied at planting (400 kg ha- of 15: 15: 15 NPK). The studies were made on two highly degraded sites in southwestern Nigeria which had been subjected to intensive mechanized cropping for a period of ... -
Comparative study on the growth and productivity of Sesbania and leucaena in the Central Plateau region,Rewanda
(1992)A study was conducted in the Central Plateau region of Rwanda to assess the productivity ofSesbania sesban and three Leucaena species in hedgerow intercropping systems. S. sesban grew and accumulated biomass most rapidly in the first 10 months of growth. During the following 6 months the fastest growth was observed in L. diversifolia (provenance Rwanda). After cutback, regrowth from S. sesban dropped whereas in the Leucaena species it increased. S. sesban produced more stakes than the Leucaena ... -
Five years of research on improved fallow in the semiarid highlands of Rwanda
(1992)Alternative technologies that maximize the use oflocal resources and improve the sustainability of crop production in Rwanda are needed. Promising species for the semi-arid highlands, where the research reported in this paper was conducted, include mucuna (Mucunaprwiens) for fallow periods of 1 4- 1 8 weeks, sunnhemp (Crotalaria ochroleuca), pigeonpea (Cajanus cajan) and desmodium (Desmodium distortum) for fallow periods of 20-24 weeks, and Sesbania sesban and Tephrosia vogelii for long fallows ...
