IITA Conference Documents

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Field and greenhouse screening for resistance to leafhoppers and thrips in cowpea
(Conference Proceedings, 1976) Raman, K.V.
Of 4705 entries in the World Cowpea Germplasm Collection, 800 showed moderate to high levels of field resistance to Sericothrips occipitalis and Empoasca dolichi and of these 100 were highly resistant. Of six lines tested under greenhouse conditions, TVu662E was highly resistant to E. dolichi, resistance being the result of antibiosis.
Biological nitrogen fixation in farming systems of the tropics
(Conference Proceedings, 1977) Ayanaba, A.; Dart, P.J.
This book is the proceedings of a symposium held at the International Institute of Tropical Agriculture, Ibadan, Nigeria in Oct. 1975. It is divided into sections on general considerations (3 papers); legumes in farming systems of the tropics (4 papers); ecology and physiology of rhizobia (6 papers); nitrogen fixation in legumes (7 papers); non-legume sources of biological N in nature (6 papers); and measuring N gains and losses in farming systems (4 papers). The following are noted.
Intercropping with cassava in Africa
(Conference Proceedings, 1978) Ezeilo, W.N.
In Africa, cassava-growing areas are located from Senegal in the west, through Nigeria and Zaire, east to Malagasy and from 15°N-15°S latitude, according to de Viliers (1965). Optimum production requires an annual rainfall of 1000-2000 mm; average annual temperatures of 25-29 °C; daylengths not greater than 15 hours; altitudes less than 2000 m above sea level; and freely draining sandy loam soils dominated by oxisols, ultisols, and alfisols. The diversity of cassava cropping systems in the lowland humid tropics is based on high population densities, personal tastes, economic and political factors, and the overall level of technological development and resource availability.
Cowpea as an intercrop under cereals
(Conference Proceedings, 1976) Wien, H.C.; Nangju, D.
One of the commonest systems involves grain legumes such as cowpea or groundnut planted under cereals such as sorghum, millet, or maize (31). Steele (32) suggests that cowpea may have come from its supposed center of origin, Ethiopia, to the West African semi-arid zone as part of such a cereal-legume farming system.
Weed control systems for upland rice production
(Conference Proceedings, 1974) Moody, K.
Nearly one-quarter of the total rice area of the world is planted to upland rice (10). At least two-thirds of the production in Latin America and West Africa is from upland culture (3, 36). Probably 30-40 percent of the rice in the world is grown following dry soil preparation (23~. Much of the upland rice in West Africa is grown on small farms under shifting cultivation. With this system, the farmer clears the underbrush towards the end of the dry season leaving the large trees of economic value intact (18). Generally the stumps and roots from~ hich the forest regenerates are left in the ground (13). The underbrush is allowed to dry and is then burnt. After the commencement of the rains, the farmer sows his crop of rice which may be mixed with other crop seeds using a hoe with which he scratches the surface soil to cover the seeds (18). Farms rarely exceed 1 hectare in size mainly~ because the farmer is unable to weed a larger area.
Weed problems and food production in developing countries
(Conference Proceedings, 1978-02) Okigbo, B.D.N.
A review covering weed importance, weed control in relation to food production, weed evolution, weed problems and weed control strategy.
Protein quality in grain legumes grown in the lowland humid tropics, with special reference to West Africa
(Conference Proceedings, 1975) Luse, R.A.; Kang, B.T.; Fox, R.L.; Nangju, D.
The grain legumes are important sources of dietary protein in the lowland humid tropics. To attain their yield potential and hence possible protein productivity, legumes grown in the lowland humid tropics (except on newly cleared land) require fertilizer Nand P. Observations in West Africa have indicated that seed yield and protein content have been raised in soybean by added Nand P. Rhizobial inoculation without fertilizer N increased seed protein from 31 to 36%. In terms of protein yield, inoculation is equivalent to 65 kg/ha of fertilizer N when used with 30 kg/ha'starter'N. Cowpea yield respon: ed to added Nand P but seed protein content was unaffected. Seed yield and seed S content of cowpea increased as the level of added soil solution S increased from near zero to about 2 ppm and then tended to remain nearly constant at higher soil S concentrations. Seed protein content was relatively unchanged. Protein content in groundnuts was not influenced by N, P or K fertilizer. The effect of K fertilization on seed yield and protein quality of grain legumes needs further investigation. Micronutrients, particularly B, Mo and Zn, may limit legume yield, but low yielding cultivars and low N PK fertilizer rates have tended to conceal this Iimitation.
Experimental designs in rice mechanization experiments
(Conference Proceedings, 1974) Little, T.M.
Special problems of experimental design arising when planning mechanization experiments are discussed, including consideration of plot and experiment size.
Herbicides in tropical soils and water
(Conference Proceedings, 1978) Ayanaba, A.
In the U. K., the amount of herbicides used on about 4.15 million hectares of agricultural land in 1973 was considered enough to provide 30 ppm if mixed evenly into the top 0.5em of the treated area (Greaves et al., 1976). How soon quantities of this kind will be used in the topics is not known. It is the responsibility of agriculturalists to maintain the productivity of the soil, and one aspect of this task is to ensure that levels of herbicides in soils and water are kept _low.
Performance of four newly released cassava varieties in a fallowed land over two cropping seasons
(Journal Article, 2025) Ossai, C.O.; Ojobor, S.A.; Ogwuche, T.O.; Akpeji, S.C.; Sunday, A.I.; Diebiru-Ojo, E.M.
Cassava (Manihot esculenta Crantz) is an important crop for humans due to its staple and industrial values. Currently the demand is more than the supply as the current output falls below the expected. This necessitated the breeding of superior genotypes that are high yielding. These superior genotypes also requires a fertile soil for optimum production. However, this has been primarily achieved through the application of organic manures and inorganic fertilizers. It is then important to evaluate four newly released cassava varieties in an organically enriched soil relative to the local best variety. Four newly released cassava varieties, Hope, Obasanjo2, Baba 70, and Game changer, and one Local Best (LB) was planted in 5-years fallowed farm lands at three plots (A, B and C) for 2 seasons. It was a three-way factorial (5-varieties*3-farms*2-seasons) arranged in a randomized complete block design and replicated three times. Data were taken on the Fresh Tuber Weight (FTW) and Stem Height (SH) per variety, and pre and post soil status. Data were analyzed using analysis of variance, while differences in varietal means were separated using least significant differences at 5% level of significance. The FTW and SH differed significantly across varieties, years and interaction between variety, farms and year, and ranged from 19.2 ± 0.5 (LB) to 41.0 ± 0.5 (Obasanjo2), 32.1 ± 0.4 (farm C) to 34.1 ± 0.4 (farm A), 30.4 ± 0.3 (year two) to 35.0 ± 0.3 (year one), and the interactions between variety and year, farms and year, and variety, year and farms were significant. The soil macro and micro elements declined in the post relative to the pre status. The fresh yield of the improved varieties Baba70, Game change, Hope and Obasanjo2 was 74%, 80.8%, 81%, and 113% higher than the local best, respectively. Yield declined in the second season due to decline inherent soil nutrient hitherto compensated by shifting cultivation in the farming community.
The importance of grain legumes in cropping systems in Africa
(Conference Proceedings, 1975) Nangju, D.
Grain legumes play an important role in cropping systems in Africa by virtue of their short duration, drought tolerance, ability to fix nitrogen from atmospheric air, and ability to grow in depleted soils and in association with cereals and root crops. In addition, grain legumes are important sources of vegetable proteins, vitamin B and calcium particularly for vegetarian diets during the hungry season. Different species of grain legumeg are grown in various forms of cropping systems. Their performance under mixed cropp ins system and their contribution to soil fertility are reviewed. It is concluded that under the present management practices in Africa, grain legumes probably contribute very little toward maintaining or enhancing soil fertility, and that higher yields obtained under mixed cropping may be attributed mainly to greater utilization of environmental resources, and lower incidence of diseases and insects. Research is urgently required to improve the contribution of grain legumes to nitrogen requirements of companion crops or the following crops in view of the high cost of nitrogen fertilizers.
The IITA farming systems program
(Conference Proceedings, 1974) Okigbo, B.
The International Institute of Tropical Agriculture (IITA) was established in 1967 on 1,000 hectares of land located at 3o 54'E longitude and 7o 30'N latitude, about 16 kiloneters north of Ibadan, the capital of the Western State of Nigeria. It is one of a network of international research institutes where priority is given to research, training and related activities aimed at quantitatively and qualitatively increasing food production in the developing countries of the world. These countries contine to experience shortages in available food supplies resulting from much higher rates of population growth as compared to the rates of increase in food production. Specifically, IITA's activities involve multidisciplinary, problem-oriented research in food crops production which, for effectiveness and rapid progress, is restricted to the major food crops of the humid tropics. The humid tropics is defined as the broad belt girdling the earth in the lower latitutes on both sides of the equator where precipitation exceeds evaporation for more than half the year and where normally the tropical rain forest constitutes the climax vegetation.
P40: Rate of seed transmission of bean common mosaic virus (BCMV) in successive generations in cowpea
(Abstract, 2025) Dauda, N.; Ajamu, D.; Baiyeri, P.K.; Ugwuoke, K.I.; Kumar, P.L.
This study aimed to understand the effect of genotype, time of infection, and seed morphometrics on seedborne virus infections in cowpea (Vigna unguiculata) transmission and the eventual impact of seed-borne viruses on cowpea yield compared to uninfected control. Experiments were performed using a Potyvirus species, bean common mosaic virus-blackeye (BCMV-BlCM). This virus is endemic in West Africa. Nine cowpea genotypes raised in 6-inch pots and maintained in an insect-proof screenhouse were mechanically inoculated at 7, 21, and 40 days after planting (DAP). Seeds obtained from both the inoculated and uninoculated control groups were planted, and the seedlings were examined for seedborne infection based on symptoms and RT-PCR diagnostics. All identified seed-borne plants were maintained until harvest and re-evaluated for seed transmission and the impact of seedborne viruses on cowpea yield in successive generations. In the first generation, percent BCMV seed transmission rates of 7.9, 4.6, and 44.4 were observed in genotypes RS018 inoculated at 21 DAP, RS075 (7 DAP), and RS012 (DAP). In the second generation, 35.1%, 0%, and 34.1% transmission rates were reported for the same genotypes. Significant reduction in seed yield and prolonged days to phenology was observed in seedborne plants when compared to uninfected controls. Early-stage protection against virus infection will reduce the risk of seed transmission in cowpeas.
Implications of high throughput sequencing of plant viruses in biosecurity – a decade of progress?
(Abstract, 2025) Fox, A.; Botermans, M.; Ziebell, H.; Fowkes, A.R.; Fontdevila, N.; Massart, S.; Rodoni, B.; Chooi, K.M.; Kreuze, J.; Kumar, P.L.; Cuellar, W.J.; Carvajal-Yepes, M.; Macdiarmid, R.M.
In the 15 years since High Throughput Sequencing (HTS) was first used for the detection and identification of plant viruses, the technology has matured and is now being used in frontline plant biosecurity applications. Anticipating the challenges this new approach was starting to reveal, recommendations were made a decade ago to streamline the application of these technologies (MacDiarmid et al., 2013). The recommendations were (1) for countries to increase baseline surveillance, (2) to address nomenclature for “data inferred” new viral sequence to differentiate from characterised viruses, and (3) to increase the focus on fundamental biological research to deal with the deluge of new virus discoveries. The progress made on these recommendations in the intervening decade has been as much about changing philosophical approaches as about advancing practical research. As we move towards a potential asymptote in the rate of virus discovery, the anticipated future challenges posed by the broader adoption of HTS in routine biosecurity applications need to be considered. In addition to these three recommendations, which remain relevant, a fourth recommendation is becoming necessary: (4) to ensure equal inclusion and access to research and technology, both locally and globally, with a particular emphasis on countries in the global south. The potential impact of these recommendations on researchers, risk analysts, biosecurity authorities, and policymakers at national and international levels to achieve a reduction of biosecurity incursions of phytopathogenic viruses will be discussed.
Between isomorphism and entrepreneurship: the impact of standardisation on product quality, market access and livelihoods in Kenyan banana production
(Abstract, 2011-10) Matui, M.S.; Ingenbleek, P.; Linnemann, A.; van Trijp, H.; Abass, A.
Delivering innovative research towards inclusive adoption of climate-smart agriculture for food and nutritional security: Book of Abstracts for the 26th Annual Symposium of the International Association of Research Scholars and Fellows
(Conference Proceedings, 2023-11-30) International Association of Research Scholars and Fellows
Seed propagation trends in Nigeria and Ghana
(Abstract, 2023) Balogun, M.
Relative performance of old and newly released yam varieties in hydroponics system for seed yam production
(Abstract, 2023) Balogun, M.; Ekundayo, M.; Ossai, C.; Jimoh, L.; Maroya, N.; Aighewi, B.; Mignouna, D.; Amele, A.; Legg, J.
Rapid multiplication of improved yam varieties is crucial to enhance farmers’s access to seeds. Seed yam production has been enhanced using hydroponics system. However, reports on use of hydroponics have been for few improved genotypes released at least one decade ago. This study assessed the amenability of released / near-release yam genotypes to hydroponics substrates. Two weeks old Breeder seedlings of three released varieties of Dioscorea alata (Akuabata, VaYam and Wonder) and four genotypes of Dioscorea rotundata (Released: Kpamyo and Asiedu, and near-release: Danacha and Meccakusa) were planted in the following hydroponics susbtrates; Riversand, Riversand+Ashed Ricehusk (RS+AH: 3:1), Cocopeat, Cocopeat+Ashed Ricehusk (CP+ASH: 3:1) and Ash. Fertigation was daily with nutrient solution as described previously. Data were taken on the Number of Single Node Vine Cuttings (SNVC) f rom 18 stands at 2 Weeks after Planting (WAP), Percentage Vine Survival (PVS), Number of Nodes (NON) at 6WAP, Number of Tubers (NOT) and Tuber Weight (TW) g at harvest. Data were analysed using ANOVA , and means were separated using Least Signif icant Differences at P=0.05. The SNVC, PVS, NON, NOT and TW of the genotypes differed signif icantly and ranged from 220 (Wonder) to 596 (Asiedu), 33.8% (VaYam) to 95.4% (Danacha), 16.0±1.4 (Danacha) to 35.1±1.4 (Asiedu), 1.4±0.1 (Danacha) to 1.9±0.1 (Akuabata), and 16.6±2.6g (Wonder) to 40.3±2.6g (Asiedu), respectively. The substrate effect on SNVC, PVS, NON, NOT and TW ranged f rom 143 (CP+AH) to 577 (RS+AH), 42.7% (CP+AH) to 60.9% (Riversand), 4.33±1.1 (Ash) to 30.3±1.1 (RS+AH), 1.0±0.1 (Ash) to 2.1±0.1 (RS+AH), and 1.4±2.3g (Ash) to 50.3±2.3g (Riversand), respectively. Genotype by substrate interactions were also signif icant. Asiedu gave the highest vine production in the hydroponics system relative to the near release varieties, but the near-release varieties Danacha and Akuabata had higher vine survival rate and number of minitubers, respectively. The implications of these f findings in evolution of the formal yam seed system are discussed.
Prospects and challenges of emerging yam formal seed systems in West Africa
(Abstract, 2023-10) Aighewi, B.; Aihebhoria, D.; Balogun, M.; Mignouna, D.
Yam (Dioscorea spp.) is a staple tuber crop produced in parts of tropical Af rica, the Caribbean, Oceania, and South Asia. Typically, the crop is grown in traditional systems where there are no dedicated seed producers and farmers use seed f rom informal sources. Recently, technologies developed at the International Institute of Tropical Agriculture, Nigeria, were deployed to initiate formal yam seed systems in Nigeria and Ghana to enhance the availability of quality seed to millions of yam farmers in West Af rica. A study was conducted using a structured questionnaire to investigate how seed companies that engage in foundation and certified seed yam production were using the new technologies, and to assess the prospects for increasing the availability of quality seed through the formal seed system, as well as the challenges encountered. Results showed that seed companies were satisf ied using new technologies such as <10 g minitubers of improved varieties, compared to the 250 g seeds of landraces in informal production systems. They also use leaf-bud cuttings in hydroponic systems in screenhouses with up to 92% plant establishment, and 65% of the companies use locally available rice husk as a growth substrate. The improved practices used in screenhouses and f ields that are inspected and certified by the relevant quality control and certification agencies have great potential in enhancing the availability of quality seed yam. However, the aeroponic system was considered complicated and expensive, and not adopted despite the 95 to 97% plant survival in the system. Major challenges of the new system include limited knowledge on the storage requirement for 1 - 10 g foundation seeds and high storage losses (up to 38%) resulting from nematode infestation when seed was produced in the field. There is also an unwillingness by farmers to accept new varieties. In conclusion, the adoption of new technologies in the formal seed system with additional knowledge on storage and pest control will mitigate major bottlenecks in quality seed yam production and availability.
Varietal characteristics of cassava: farmers' perceptions and preferences in semiarid zone of west Africa
(Conference Paper, 2003-09) Kormawa, P.; Tshiunza, M.; Dixon, A.; Udo, E.; Okoruwa, V.
The study examines and models Farmers' perceptions and preferences of cassava· varietal characteristics vis-i-vis the decision ' to adopt cassava cultivars in their fields. The paper is built on the concept of the effect of technology-specific factors on adoption. By way of threshold decision modelling for each of the countries considered, the results reveal different scenario. Based on the varietal characteristics considered, environmental resistance quality (ERQ), high-yielding quality (HYQ), early maturing qualities (EMQ), leaf quality (LQ), inground storability quality (lSQ) and taste quality (TQ) have declining importance in the order of Iisting. As such, environmental resistance quality appears a major varietal characteristic that the farmers perceived and preferred for cultivating any cassava cultivar in the zone. The results, therefore, reinforce the relative importance of varietal characteristics in the choice and preference of cassava cultivars by farmers; it is, therefore, imperative for breeders to develop cultivars that will be acceptable to the farmers considering their level of preference and perceptions.

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