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Conference Documents: Recent submissions
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The structure and function of DSSAT
(1991) -
Soil constraints for sustainable upland crop production in humid and subhumid West Africa
(1991)Major upland soils in the humid and sub humid zones of West Africa consist of low activity clays (LAC) Alfisols, Ultisols and Oxisols. Alfisols which are less leached and have a high base saturation are more dominant in the sub-humid zone. Chemically they are more fertile, but they have a low structural stability. The Ultisols/Oxisols which are more prevalent in the humid zone, are less fertile, with major nutrient and acidity constraints. The major constraints on sustainable crop production on ... -
Preliminary results at IITA in breeding plantain for black sigatoka resistance in Africa
(1991)Africa accounts for 50 of all plantain produced in the world. These plantains are overwhelmingly import as a food crop for local consumption. Black sigatoka has now invaded Africa, thereby endangering this important food source. The long term solution lies in the creation of black sigatoka resistant plantains. The available Musa germplasm at IITA was screened for female fertility with AA black sigatoka resistant diploids. Sixteen `French' plantains and seven `False Horn' plantains produced seed. ... -
Representativeness of farmers and sites in onfarm trials
(1991)In the farming systems approach to technology development, trials are carried out on a limited number of farmers’ fields. Results of these trials are extrapolated to the entire target area and used either to identify directions for further research or to develop recommendations for farmers. Extrapolation is obviously not valid if farmers and fields are not representatives of the target area. In practice however, it is difficult to select a sample of farmers according to predetermined criteria. ... -
Framework for orientation of Striga research at IITA
(1991)Striga research at IITA is conducted by multidisciplinary team. To coordinate and focus the activities of the team, two models have been developed that attempt to provide a framework for research. One model addresses the agro biological aspects of Striga seed population dynamics. This model shows the combination of, and the necessary impact of, each of various technological inputs to stop or decrease Striga seed population growth. The second model has been adapted to assess the likelihood of ... -
Aerial release of acarine biological control agents on carrier materials
(1991)Laboratory and field experiments were performed to test several materials on their suitability as carrier for the aerial release of phyroseiid mites. Relatively few mites adhered to the materials. Nevertheless, mites were rettieved in cassava fields after a mass release, using oat flakes as carrier material. This method can be suitable when large areas are to be supplied with low mite densities. -
Host plant resistance of cassava green spider mite (CGM) (Mononychellus tanajoa Bondar) at IITA
(1991)Major upland soils in the humid and sub humid zones of West Africa consist of low activity clays (LAC) Alfisols, Ultisols and Oxisols. Alfisols which are less leached and have a high base saturation are more dominant in the sub-humid zone. Chemically they are more fertile, but they have a low structural stability. The Ultisols/Oxisols which are more prevalent in the humid zone, are less fertile, with major nutrient and acidity constraints. The major constraints on sustainable crop production on ... -
Breeding for resistance to Striga and Alectra in cowpea
(1991)An outline is given of the progress made in a systematic breeding programme set up in Nigeria to develop improved cowpea cultivars with combined resistance to Striga gesnerioides and Alectra vogelii along with multiple disease and insect resistance. Several sources of resistance to both parasitic weeds have been identified. Of these, B301, a land race from Botswana has shown complete resistance to S. gesnerioides and A. vogelii. This was crossed with a susceptible cultivar, IT84S-2246-4, which is ... -
Progress in breeding maize for Striga tolerance/resistance at IITA
(1991)IITA has been breeding maize for Striga tolerance/resistance (STR) since 1982. Populations of Striga hermonthica from Nigeria have been used to challenge maize germplasm. Initially (1982-1984), field screening was done under natural infestation, but variability both within sites and across years was high. Since 1985, fields have been infested artificially. Artificial infestations have been improved with experience, and variability has now declined to an acceptable level. The most important ...