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Journal and Journal Articles: Recent submissions
Now showing items 1581-1600 of 5273
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Effect of five years of notillage and mulch on soil properties and tuber yield of cassava on an acid Ultisol in southeastern Nigeria
(1990)The effect of no-tillage and mulch on soil properties and tuber yield of cassava was studied over a five year period on an infertile, acid Ultisol in south-eastern Nigeria. Mulch was applied at a rate of 12 t ha−1 as a split application once at planting and once six months after planting. No chemical fertilizers were used during the trial. Bulk density and proportion of micropores (pore radius, r, <1.4 µm) were greater, and proportion of macropores (r>14.4 µm) lower, with no-tillage. Water ... -
Alley farming
(1990)Alley farming involves the cultivation of food crops among hedgerows of multipurpose trees. Use of woody legumes provides N-rich mulch and green manure to maintain soil fertility and enhance crop production, and protein-rich fodder for livestock. The success of alley farming depends on a number of technical factors—choice of suitable woody species, successful establishment of the hedgerows, and appropriate management of the hedgerows. The alley farming technique being a scale-neutral system is ... -
Screening of cowpeas for resistance to Clavigralla tomentosicollis Stal (Hemiptera: Coreidae)
(1990)A laboratory screening method was developed for evaluating resistance of cowpea, Vigna unguiculata (L.) Walp, to Clavigralla tomentosicollis Stål. The technique uses dry cowpea seeds, which were judged better than fresh seeds or fresh pods, to identify protracted nymphal development and high cohort mortality. Two wild cowpea relatives, TVNu 72 and TVNu 73, were highly resistant to C. tomentosicollis. Insect mortalities were >85% on the resistant lines as compared to <25% on the susceptible lines. ... -
Alleviation of soil constraints to crop growth in the upland alfisols and associated soil group of the West African Sudan savannah by tied ridges
(1990)The climate of the West African Sudan savannah (annual rainfall of 600–900 mm and a monomodal rainy season of 3–4 months) is characterized by frequent long- and short-term droughts. Crop growth in the Alfisols and associated soil groups is further constrained by soil compaction, low soil fertility, high soil temperatures, low soil water retention and available water holding capacity, and low water infiltration rate. Tied ridges, ridges with earthen bunds constructed at right angles to the self-same ... -
Collecting germplasm in Zimbabwe
(1989)Reports the findings of a mission carried out by the International Institute of Tropical Agriculture in Zimbabwe to gather genetic resources of cowpea, rice, bambarra groundnut and their wild relatives. 461 samples of 365 species were collected. Sampling was made over 140 sites of both natural vegetation and cultivated habitats. The team was able to gather samples from farmers' stores (43%), markets (6%) and from standing crops 39%. 12% of the samples collected were from wild vegetation. -
Shoottip culture and thirdcountry quarantine to facilitate the introduction of new Musa germplasm into West Africa
(1990)Tissue culture is increasingly being used as a vehicle for the safe exchange of Musa germplasm. However, certain pathogens, e.g banana bunchy-top virus (BBTV), may pass undetected through in vitro culture. To meet the urgent need for introducing new desired germplasm for Musa breeding and reduced the risk of pathogen transfer, a germplasm-movement strategy based on two independent safeguards, viz. shoot-tip culture and third-country quarantine, was adopted. More than 270 Musa accessions have been ... -
Farmers maize yields in S.W. Nigeria and the effect of variety and fertilizer: an analysis of variability in onfarm trials
(1990)Farmer-managed trials in developing countries often show great variability in yield and treatment effects. The use of statistical techniques is demonstrated to explain this variability in a maize + cassava intercropping trial in southwestern Nigeria. Concomitant variables, measured in the trial fields, are used as covariates in the ANOVA and as regressors in the analysis of mean site yield. It was found that a new maize variety (TZSR-W) performed better than the lcoal irrespective of farmers' yield ... -
The role of kairomones in prey finding by Diomus sp. and Exochomus sp. two coccinellid predators of the cassava mealybug, Phenacoccus manihoti.
(1990)We studied searching behaviour of Diomus sp., a coccinellid predator introduced into Africa as a natural enemy of the cassava mealybug, when searching on cassava leaves, and compared its behaviour with the searching behaviour of Exochomus sp., an African predator of mealybugs (MB's). Female adults of Diomus and Exochomus spent more lime searching on cassava leaves previously infested with cassava MB than on clean cassava leaves, in response to substances produced by MB's (wax and/or honeydew) still ... -
Tillage effects on cassava (Manihot esculenta) production and some soil properties
(1990)Cassava is traditionally grown on tilled soils. Interest in reduced-tillage systems is increasing in the humid tropics due to erosion problems. A field study was conducted on a sandy clay loam Ultisol to compare cassava performance in three tillage systems effects on soil water and organic carbon content. Tillage treatments were: (1) ploughing, harrowing and ridging (conventional); (2) digger-made holes (minimum); (3) pushing the sharpened end of cassavs cuttigs directly into the soil (no-till). ... -
Computer acquisition and analysis of insect feeding monitor data
(1990)Electronic insect-feeding monitors are increasingly being used to study the feeding behavior of piercing-sucking insects in relation to host resistance and biotypes. The original AC design has been modified several times to simplify and expand the signal generator and signal processor. We report a method to improve the monitoring stage by using an MS-DOS computer to replace strip chart recorders. We present fragments of custom software in BASIC, C, and 8086 assembly language designed to simplify ... -
Analysis of epidemics of leptosphaerulina leaf spots on alfalfa and white clover in time and space
(1990)The spatial and temporal development of leaf spots on alfalfa(Medicago sativa ‘Are’ and Ladino-type white clover (Trifolium repens ‘Regal’) caused by Leptosphaerulina trifolii were mentioned during spring 1987, fall 1987, and spring 1988. In spring 1987, diseases gradients developed from diseased alfalfa to both white clover, little diseases developed on either host in plot with diseases clover at the focus. In fall 1987 and spring 1988, disease developed from alfalfa or clover on both hosts. ... -
Collecting germplasm in Lesotho
(1990)Reports the findings of a collecting mission in Lesotho carried out by the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria and the Germplasm Institute CNR, Bari, Italy in April 1988. The main objective was to collect genetic resources of cowpea and bambara groundnut, and gather information about wild species of the genus Vigna in the country. 46 accessions of local varieties of cowpea were collected, together with 26 Phaseolus vulgaris, 6 Triticum aestivum,24 Zea mays and ... -
Collecting in Swaziland and Zimbabwe
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Fatty acid composition and insect resistance in Vigna unguiculata seeds
(1990)Fatty acid composition of extracted oils from 58 lines of cowpea (Vigna unguicuiata (L) Walp) was investigated by gas‐liquid chromatography (GLC). Considerable variability was observed in the fatty acid profile, though palmitic (16:0), linoleic (18:2) and linolenic (18:3) acids were the dominant components in each line. Correlation analysis shows that seed oil composition differs according to response to Callosobruchus maculatus (F). In fact, besides a group of correlations common to all lines, ... -
Structure of south central agricultural production
(1990)Using a dual economic specification of a multi- product technology, the structure of agricultural production was tested for five South Central states purpose. (Texas, Oklahoma, Arkansas, Mississippi, and Louisiana). A comprehensive set of output supplies and input demands comprised the estimation equations in each state. Evidence of non-joint in a subset of commodities was detected in four of five states. Several commodities also satisfied sufficient conditions for consistent aggregation. However, ... -
Assessment of genetic variability for N2 fixation between and with provenance of Leucaena leucocephala and Acacia albida estimated by 15N labelling techniques
(1990)Nitrogen fixed in 13 provenances of Acacia albida and 11 isolines of Leucaena leucocephala inoculated with effective Rhizobium strains was measured by 15N techniques and the total N difference method. In the test soil, on the average, L. leucocephala derived about 65% of its total N from atmospheric N2 fixation compared to about 20% by A. albida. Significant differences in the percentage of N derived from atmospheric N2 (% Ndfa) occurred, between provenances or isolines within species. The % Ndfa ... -
Population dynamics of Typhlodromalus limonicus from Colombia, an introduced predator of the exotic cassava green mite in West Africa
(1990)The introduction of Typhlodromalus limonicus (Garman & McGregor) sensu lato is a major component of an on-going biological control campaign against the exotic cassava pest Mononychellus tanajoa (Bondar) in Africa. However, long-term establishment of this exotic phytoseiid predator has not yet been achieved. The Colombian biotype of 33 limonicus was evaluated as a biological control agent in Nigeria and Bénin by assessing its population response to selected abiotic and biotic factors. In field ... -
Genetic variability in symbiotic nitrogen fixation within and between provenances of two Casuarina species using the 15Nlabelling methods
(1990)Differences in the nitrogen-fixing abilities of provenances of Casuarina equisetifolia and C. cunninghamiana were assessed in pot experiments. Three methods, the 15N isotope dilution, the A value and total N difference were used to measure N2 fixed. There was a good agreement between the A value and isotope dilution methods for measuring N2 fixed. The total N difference method gave unreliable values, with large coefficients of variation. There were significant differences in the proportions and ... -
Influence of reference trees on N2fixation estimates in Leucaena leucocephala and Acacia albicia using 15N_ labelling techniques+A51
(1990)We examined the suitability of four reference crops, i.e., two non-fixing trees,Cassia siamea andEucalyptus grandis, and two uninoculated fixing trees,Leucaena leucocephala andAcacia albida, for measuring fixed N2 fixed in inoculatedL. leucocephala andA. albida grown for 36 weeks in pots. The15N isotope-dilution (involving the addition of equal amounts of labelled N fertilizer to the non-fixing and the fixing plants) and theA-value (with different amounts of labelled N fertilizer added to the ...
