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Journal and Journal Articles: Recent submissions
Now showing items 1921-1940 of 5273
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Symptomatology and development of banana streak badnavirus, under natural conditions in Ibadan, Nigeria
(2000)A field experiment with suckers taken from five improved plantain hybrids and one landrace with typical symptoms of banana streak badnavirus (BSV) infection was established at Ibadan (Nigeria) to investigate climatic factors affecting BSV symptom development and to identify parameters useful in genotype evaluation for BSV incidence. Weekly monitoring of individual plants for symptom incidence and severity indicated that symptom expression was more severe during the rainy season (July to October-November) ... -
Implications of bipphysical site characteristics on growth and sustainable cassava production in the savannas of Nigeria
(2000)In the Nigeria savanna (derived, Guinea and Sudan) belt, continuous production of crops with short or no fallow cycle, with small amounts or no fertilizer and mixed cropping is a prevalent land use system. Cultivation of cassava as a staple supplementary food source in relatively degraded savanna lands it common. Productivity of the on-farm crop is greatly lower than its potential. Therefore we studied the effect of several biophysical factors on growth and productivity of cassava. Field data ... -
Statistical tools to evaluate sensory data fro testing fruit quality of Musa
(2000)Recent successes in the conventional cross-breeding of plantains and cooking bananas by genetic improvement programmes will inevitably lead to an increase in the number of new clones that require testing before release to farmers. In most cases testing focused on disease resistance and yield but little attention was given to fruit quality. The International Institute of Tropical Agriculture (IITA) has developed a procedure for testing the fruit quality of landraces and hybrid Musa genotypes. This ... -
Potentiel de productivite et efficacite technique du secteur agricole en Afrique
(2006)This study utilizes frontier metaproduction functions to analyze inter‐region agricultural productivity differences. Technical efficiency scores are examined through estimation of stochastic frontiers for 16 African countries divided into three different regions (West Africa, East and Southern Africa, and North Africa) from 1970 to 2001. The idea is to explore the differences in efficiency and technological gaps of agricultural sector. Apart of common traits that characterize African agricultural ... -
Analyse des determinants du choix des methodes de lutte contre les pestes dans les plantations de cacao et cafe au sud Cameroon
(2000)Cet article analyze the determinants of cholera des méthodes de lutte contre les pestes, dans les plantations de café et de cacao des communautés paysannes du sud-Cameroun. Les méthodes sont chimiques, traditionnelles, et mixtes. Pour capter l'influence des variables socio-économiques sur la probabilité d'utilisation des différentes méthodes, a multinomial logit modèle a été utilisé. Les résultats obtenus révèlent the variables which influence significantly the choix des différents moyens utilisés ... -
Undesrtanding the Musa genome: an update
(2000)Scientific strategies for crop improvement ensue from genetic knowledge gain from the relevant breeding populations. Few genetic studies were undertaken in Musa before the 1990s, despite the importance of the crop in human diet in the tropics. It was believed that genetic studies of most cultivated Musa, a virtually sterile triploid crop, were impossible. This explains the absence, until recently, of inheritance studies in triploid plantain and banana and the lack of genetic markers. Although ... -
Taxonomic value of calcium oxalate cystals in Musa germplasm
(2000)Epidermal and histological characterization of Musa species and cultivars were carried out to investigate the descriptor value of calcium oxalate between groups and subgroups of cultivars. Epidermal peels of the bracts of selected plantain and banana cultivars stained with 0.01% safranin solution and permanent mounts of microtometric sections of fruits, bracts and peduncles stained with hydrogen peroxide and silver nitrate were microscopically examined for their crystal content and features. Bract ... -
Variation in soil nutrient levels under multispecies hedgerow cropping with plantain
(2000)Spatial nutrient distribution was studied under a multi-species hedgerow cropping with plantain on an acid ultisol in southeastern Nigeria. The objective of this study was to evaluate variation in soil nutrients under alleys formed by multi-species hedgerows at three sampling sites: 0.5 m around plantain stands, from 0.5 m to 1.5 m away from plantain stands and under multi-species hedgerows. Nutrient distribution (0-10 cm soil layer) varied significantly across the three sampling sites. This study ... -
A procedure for allocating heterogenous units to treatment groups
(2000)In allocating experimental subjects that are not homogeneous (eg. animals, socio-economic units such as households, etc.) to treatment groups, certain attributes which are likely to affect the results if not accounted for, are usually used as classification variables prior to allocation. This can easily be done for one or two variables by dividing the observed range(s) of the key classification variable(s) into sub-groups and ensuring, as far as possible, that treatments appear in all groups (as ... -
Response of East African highland bananas to black Sigatoka and Cladosporium leaf speckle under tropical humid forest lowland conditions in West Africa
(2000)The responses of 19 East African highland (EAH) banana cultivars (AAA and AA genomes) and two reference cultivars to black sigatoka (Mycosphaerella fijiensis Morelet) and Cladosporium leaf speckle (Cladosporium musae Mason) were studied in 1993 at Onne (southeastern Nigeria) under ecological conditions of the tropical humid forest lowlands. Plants were evaluated before flowering during the rainy season when conditions were favorable for both plant growth and disease development. Disease development ... -
Yield loss from plant parasitic nematodes in East African highland banan (Musa spp. AAA)
(2000)East African Highland bananas (Musa spp., AAA) also known by their vernacular name ‘matooke', are a major staple food for the densely populated high elevation regions of Eastern and Central Africa. Banana production, however, is declining due to increased pest and disease pressure. Nematodes are considered to be a major constraint. An experiment was established at the East and Southern Africa Regional Centre of the International Institute of Tropical Agriculture at Sendusu (Uganda) to assess the ... -
Barriers to interspecific hybridization between Vigna unguiculata and Vigna vexillata
(1992)Interspecific hybridization between Vigna unguiculata and V. vexillata always failed: no seed was obtained in both crossing directions. Two different barriers to crossability were found: a pre-zygotic barrier and a post-zygotic one. Many abnormalities were observed in pollen-tube development, which reduced the percentage of fertilization to 18–30%. Differences in the percentage of fertilization were detected between the two accessions of V. vexillata involved in the interspecific crosses. The ... -
Maize storage practices and their influence on aflatoxin contamination in stored grains in four agroecological zones in Benin, West Africa
(2000)Aflatoxin level in 300 farmers' stores in four agro-ecological zones in Benin, a West African coastal country, were determined over a period of 2 years. At sampling a questionnaire was used to evaluate maize storage practices. Farmers were asked what storage structure they used, their storage form, storage period, pest problems in storage and what was done against them. Beninese farmers often changed their storage structures during the storage period, transfering the maize from a drying or temporary ... -
Influence of insect infestation on aflatoxin contamination of stored maize in four agroecological regions in Benin
(2000)Insect species and damage levels were evaluated and related to aflatoxin content in maize sampled from farmers' stores in four agroecological zones over a two-year period in Benin, West-Africa. In 1993, no aflatoxin was detected in maize that was free of isect damage. In the same year; in maize with more than 70 % of cobs damaged by insects 30.3 % were aflatoxinpositive, with a mean aflatoxin contamination of 77.8 ppb (parts per billion or kg). Grain moisture increased with damage levels. The mean ... -
Effet de la fumure en potassium sur le developpement, la survie et la fecondite de Sesamia calamistis Hampson (Lepidoptera: Noctuidae) et de Eldana saccharina Walker (Lepidoptera: Pyralidae)
(2000)The effect of potassium application to maize plants on the development, survival and fecundity as well as larval and pupal weight of Sesamia calamistis and Eldana saccharina were studied in the laboratory. Six different potassium treatments corresponding to 0, 30, 60, 60, 90, 120 and 150 kg K2O/ha were used. Potassium had no influence on larval and pupal developmental time or longevity of adult S. calamistis. The highest larval mortality was observed at 0 and at 150 kg K2O/ha. Increased doses (> ... -
Cycle biologique duree des stades larvaires du criquet puant, Zonocerus variegatus (Linne, 1758) (Orthoptera: Pyrgomorphidae) au sud du Benin
(2000)The life cycle and development of Zonocerus variegatus (variegated grasshopper) from southern Benin was studied at the International Institute of Tropical Agriculture (IITA) Benin Station, from March 1992 to August 1994. Hoppers of the 1st to the 5th stage were collected from uncultivated fields in the Atlantic Province and placed in cages and their development evaluated by counting the number of insects in each stage every two days until the adult stage. Mating and the number of egg pods were ... -
Metafrontier analysis of technology gap and productivity difference in African agriculture
(2006)Agricultural productivity in Africa from 1971 to 2000 is examined using the recently developed metafrontier function technique, for the purpose of studying differences in efficiency and technology gap across different regions of the continent. The results support the view that technology gap plays an important part in explaining the ability of agricultural sectors in one region to compete with agricultural sectors in different regions in Africa. The study has also evidenced that average technical ... -
Investigation of inoculum threshold and latent infection in Colletotrichum gloeosporiodes f. sp. manihotis in cassava cultivars
(2000)Studies were conducted at the advance pathology laboratory and glasshouse at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, to determine the inoculums threshold of fungal suspensions at different concentration levels, and also to investigate latent infection of cassava anthracnose disease pathogen, (colletotrichum gloeosporioides f. sp. Manihotis), in cassava cultivars. This study showed that fungal suspension could initiate disease infection at very low inoculums ... -
Efficacy of antimicrobial plant crude extracts on the growth in Colletotrichum gloeosporiodes f. sp. manihotis
(2000)This study was conducted to investigate a cheap and readily available alternative control measure for cassava anthracnose disease causal agent (Colletotrichum gloeosporioides f. sp. manihotis), through the use of antimicrobial crude plant extracts such as neem (Azadirachta indica), bitter leaf (Vernonia amygdalina), Ocimum gratissimum and Xylopia aethiopica, on the fungal growth parameters (mycelial growth, sporulation and germ tube development). The extracts at concentration levels of 25, 50, 75 ... -
Spatiotemporal associations in beetle and virus count data
(2000)This paper analyzes two insect-related sets of agricultural field data. Both comprise spatially referenced count data sampled on a series of occasions. One concerns carabids (ground beetles) in cereals, the other the incidence and spread of an aphid-vectored virus disease of lupins. For both sets, the major objective was to describe and quantify the stability through time of the spatial patterns found for each occasion; this was measured by the spatial association between successive samples. ...