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Journal and Journal Articles: Recent submissions
Now showing items 1761-1780 of 5273
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Seed damaging field pests of cowpea (Vigna unguiculata) L.Walp.) in Benin: occurance and pest status
(1994)Three insect groups, known from the literature, were confirmed to make up a seed pest complex in cowpea fields in Benin Republic (West Africa). Several species of heteropteran pod‐sucking bugs (PSBs), two lepidopteran species, namely Maruca testulalis (Geyer) and Cydia ptyehora (Meyrick) and the weevil Apion varium Wagner occurred throughout southern Benin. Field infestations of PSBs and M. testulalis were always present, whereas A. varium and C. ptyehora occurrence was sporadic. Seed damage ... -
Establishment and spread of Gyranusoidea tebygi Noyes and Anagyrus mangicola Noyes (Hymenoptera: Encyrtidae), two biologigal control agents released against the mango mealybug Rastrococcus invadens Williams (Homoptera: Pseudococcidae) in Africa
(1994)Two specific endophagous parasitoids Gyranusoidea tebygi and Anagyrus mangicola, of Indian origin, were mass‐reared at the International Institute of Tropical Agriculture in Cotonou and released against the mango mealybug Rastrococcus invadens, in collaboration with national biological control programmes. G. tebygi was released in the following countries: Benin, Gabon, Ghana, Nigeria, Sierra Leone and Zaire. In Togo, it had been released earlier and studied during another project. This parasitoid ... -
Virulence characteristics of a new race of the parasitic angiosperm, Sriga gesnerioides, from southern Benin on cowpea (Vigna unguiculata)
(1994)An in vitro growth system was used to determine the virulence of two samples of Striga gesnerioides from Zakpota in southern Benin. Cowpea variety B301, previously considered resistant to all races of S. gesnerioides, was susceptible to both samples of the parasite. Two other cowpea varieties, 58–57 and IT81D-994, were totally resistant. Resistance in 58–57 was associated with a hypersensitive necrosis of infected roots, whilst IT81D-994 supported production of small S. gesnerioides tubercles with ... -
Effect of boiling on the texture of cassava clones: a comparison of compressive strength, intercellular adhesion and physiochemical composition of the tuberous roots
(1994)A highly significant relationship was found between the compressive strength of eight boiled cassava (Manihot esculenta Crantz) tuberous roots and their intercellular adhesion, as measured by a retained dry weight method, suggesting that compressive strength is a measure of cell separation. In general, compressive strength is related to amylopectin content, intercellular adhesion strength and moisture levels. The addition of calcium ions to the boiling water progressively increased compressive ... -
Breeding of cassava for low cyanogenic potential: problems, progress and prospects
(1994)The starchy staples of cassava (tuberous roots) provides more than half the calories consumed by more than 200 million people in sub-Saharan Africa, and the leaves are often used as a vegetable providing protein, vitamins and minerals. The cyanogenic potential of cassava has often been cited as a causal factor of health problems, particularly in areas where cassava roots are not properly processed. Provision of improved genotypes with low cyanogenic potential would ameliorate these problems. ... -
Persistence and recovery of introduced Rhizobium ten years after inoculation on Leucaena leucocephala grown on an Alfisol in southwetern Nigeria
(1994)Establishment of Leucaena leucocephala was poor at Ibadan (Transition forest-savanna zone) and Fashola (savanna zone, 70 km north of Ibadan) in southwestern Nigeria as a result of low soil fertility and the presence of only a few native rhizobia capable of nodulating it. Inoculation with L. leucocephala at these two locations in 1982 resulted in striking responses with Rhizobium strains IRc 1045 and IRc 1050 isolated from L. leucocephala grown in Nigeria. The persistence of inoculated effective ... -
Breeding potatoes for developing countries using wild tuber bearing Solanum spp. and ploidy manipulations
(1994)The use of ploidy manipulations in potato breeding has been successfully applied by breeders at the International Potato Center (CIP) as a tool for germplasm enhancement and for the introduction of desirable genes of wild species into the cultivated gene pool. This methodology consists in reducing the ploidy level using haploids (2n = 2x = 24) and increasing it through the utilization of 2n gametes. It takes advantage of working at the 2x level to develop genotypes which combine multiple pest/disease ... -
Transient gene expression in electroporated banana (Musa spp., cv. Bluggoe, ABB group) protoplasts isolated from regenerable embryogenic cell suspensions
(1994)Electroporation conditions were established for transient expression of introduced DNA in banana (Musa spp., cv. 'Bluggoe') protoplasts isolated from regenerable embryogenic cell suspensions. The following parameters were found to be highly influential: electroporation buffer, polyethylene glycol treatment and its duration before electroporation, use of a heat shock, and chimaeric gene constructs. The maximum frequency of DNA introduction as detected by an in situ assay for transient expression ... -
Inheritance of albinism in banana and plantain (Musa spp.)
(1994)Few genetic markers are available in Musa spp. as a result of a lack of inheritance studies. Full-sib diploid (2n = 2x = 22) plantain-banana hybrids of the International Institute of Tropical Agriculture were selfed or outcrossed with other diploid bananas, one of which is an improved selection from Central America. Three populations having albinos (complete lack of chlorophyll in any plant tissue) were produced. The segregation ratios for albinism suggested that this deleterious trait is controlled ... -
Inheritance of black sigatoka disease resistance in plantainbanana (Musa spp.) hybrids
(1994)Black sigatoka (Mycosphaerella fijiensis Morelet), an airborne fungal leaf-spot disease, is a major constraint to plantain and banana (Musa spp.) production world-wide. Gaining further knowledge of the genetics of host-plant resistance will enhance the development of resistant cultivars, which is considered to be the most appropriate means to achieve stable production. Genetic analysis was conducted on 101 euploid (2x, 3x and 4x) progenies, obtained from crossing two susceptible triploid plantain ... -
Genetics analysis of apical dominance and improvement of suckering behaviour in plantain
(1994)Apical dominance, i.e., the inhibition of lateral bud growth due to growth substances released by the terminal bud, has been considered as a limiting factor for the perennial productivity of plantains (Musa spp., AAB group).Segregation ratios in F1and F2plantain–banana hybrids suggest that inheritance of apical dominance is controlled by a major recessive gene, ad. The dominant Ad allele improved the suckering of plantain-banana hybrids, as measured by the height of the tallest sucker at flowering ... -
Effect of time to first shoot removal and the amount of shoots removed on the yield and quality of cassava leaves and tubers
(1994)The effect of time to first shoot removal and the amount of shoots removed on the yield and quality of cassava leaves and tubers were investigated in two experiments carried out at IITA, Nigeria using two cassava varieties, TMS 30572 and TMS 91934. Four different times to first shoot removal, 8, 14, 20, and 52 weeks after planting (WAP), i.e. SR8, SR14, SR20, and SR52, and five different amounts of shoot harvested: no shoot removed, tip only, tip and two fully developed leaves, tip and five fully ... -
The effect of laval diet on the growth and development of Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and Eldana saccharina Walker (Lepidoptera: PYralidae)
(1994)Sesamia calamistis Hampson and Eldana saccharina Walker larvae were reared at 25°C on pieces of stem from five indigenous African grasses. All five, Andropogon sp., Panicum maximum Jacq., Pennisetum polystachion (L.) Schult., P. purpureum L. and Sorghum arundinaceum (Desv.) Stapf. have been reported as host plants for one or both species. Larval survival, larval and pupal period and pupal weight were recorded and compared to values of these parameters for larvae reared on stems of maize and on ... -
Natural levels of fungal infections in grasshoppers in northern Benin
(1994)The infection of grasshoppers by naturally occurring, entomopathogenic fungi was monitored at two sites in Malanville, northern Benin, Africa. Grasshoppers were collected and recorded from the sites between June and December 1992 and all of them, barring the first instars, were incubated in ventilated cages. At the first site, 1343 individuals of 35 grasshopper species were incubated, and at the second site, 857 individuals of 36 grasshopper species were incubated. Three hyphomycete fungi ... -
Quantitative methods for assessing the severity of anthracnose on yam (Dioscorea alata)
(1994)Two methods (the individual leaf method and whole plant method) for the quantitative assessment of the incidence and severity of anthracnose (Colletotrichum gloeosporioides on yam were developed and evaluated in the field over 3 growing seasons and are proposed for use in epidemiological studies. The percentage leaf/plant area affected by anthracnose and therefore unable to photosynthesize was used to produce disease assessment keys. -
The effects of alley cropping and fertilizer application on continuously cropped maize
(1994)A trial was conducted to study the long-term effects of alley cropping on maize under continuous cropping with and without fertilizer. Maize was planted twice a year for four years. Maize yields were higher with alley cropping than without alley cropping from the fourth crop onward. Fertilizer application increased yield for each crop. Average yields over the eight crops were highest for the combination of alley cropping and fertilizer application. The long-term effects of the treatments on maize ... -
PYrenophora triticirepentis as a component of the fungal flora of winter wheat seed in New York
(1994)The occurrence of P. tritici-repentis among the fungal flora of soft white winter wheat seed in New York, USA, was assessed during 1990-91. The fungus was recovered from 54% of the seed lots in 1990 and from 36% of the seed lots in 1991, infecting an av. of 2.1 and 0.6% of the seeds, respectively. Seed infection by fungal pathogens was generally low in 1991. Alternaria spp. were the fungi most commonly associated with soft white winter wheat seed in both years. Stagonospora [Leptosphaeria] nodorum, ...
