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Conference Documents: Recent submissions
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The role of tissue culture in the establishment of disease free germplasm for international distribution
(1990)Meristem-tip culture is being used to eliminate viruses from plants. The fact that some viruses are easier to eliminate than others has been utilized in thermotherapy and chemotherapy, along with meristem-tip culture, to increase the efficacy of disease elimination. Tissue culture materials are considered the most suitable form for international exchange of vegetative plant materials and the method is well accepted by national quarantine authorities. Clonal germplasm of cassava and sweet potato ... -
Longtern fertilizer trials on alfisols in West Africa
(1990)Results of longterm fertility trials have been useful in identifying long-term nutrient needs and problems arising with continuous and intensive cropping on Alfisols. Available data have shown that high and sustained crop yields can be obtained with judicious and balanced NPK fertilization, combined with organic material amendments. Although the need for secondary and micro nutrients has not been clearly identified, increasing problems can be expected with more intensive and unbalanced fertilizer ... -
Media forum for agriculture
(1990) -
Embryological study of crosses between Vigna unguiculata and V. vexillata
(1990)Early embryogenesis up to 8 days after pollination was characterized in V. unguiculata. When crosses were performed between V. unguiculata and wild V. vexillata, seeds were not obtained due to crossability barriers. In most cases pollen tube growth was arrested in the stigmatic tissue. In the 15-20% of ovules which were fertilized, embryo development was normal up to the globular stage, but then (5-8 days after pollination) the embryo began to collapse. -
Breeding cassava and sweet potato for pest and disease resistance in Africa
(1990)IITA's research in breeding cassava and sweet potato for resistance to pests and diseases of major economic importance in Africa is discussed under the headings: breeding cassava for resistance to pests (cassava green spider mite (Mononychellus progresivus and M. tanajoa) and cassava mealybug (Phenacoccus manihoti)); breeding cassava for resistance to disease (African cassava mosaic geminivirus, cassava bacterial blight (Xanthomonas campestris pv. manihotis) and cassava anthracnose disease ... -
Cowpea (Vigna unguiculata [L.] Walp.) germplasm collection in southern Italy and preliminary evaluation
(1990)In Italy cowpeas are grown primarily for green pod production. During 1986-88, 3 collecting missions covering the regions of Campania, Basilicata, Apulia and Calabria were mounted by the Germplasm Institute, Bari. A total of 177 seed samples were collected (147 of cowpeas and 30 of asparagus beans (V. unguiculata subsp. sesquipedalis)) from 120 sites. Severe genetic erosion was noted, particularly in Basilicata and Calabria, due to farmers no longer growing the crop or using seed from commerical ... -
Preexisting phenols and resistance to aphid in cowpea (Vigna unguiculata [L.] Walp.)
(1990)Phenolic compounds were analysed in leaf samples from 9 lines known to be resistant or susceptible to aphids (mainly Aphis craccivora but also, to a lesser extent, A. fabae). Resistant lines TVu3000, IT84E and IT83S742 had higher flavonoid glycoside contents than the susceptible lines VITA7, TVu3236 and IT82E. In the other 3 lines there was no clear relationship, which was attributed to sampling errors. Some of the phenolic compounds identified were tested in feeding experiments with A. fabae. The ... -
Nutritional evaluation of wild and cultivated species of cowpea
(1990)Data are given on seed characteristics and nutritive value for 6 accessions of 4 wild Vigna taxa (V. vexillata, V. oblongifolia, V. gracilis and V. unguiculata subsp. dekindtiana) and 27 cultivated V. unguiculata varieties. The 100-seed weight ranged from 2 to 6 g among wild and from 6 to 24 g in cultivated accessions. Protein content was significantly lower in cultivated than in wild accessions (22.3-25.5% vs. 23.4-28.2%) while the reverse was true for in vitro protein digestibility (79.5-82.5% ... -
Biochemical seed analysis in relation to bruchid resistance
(1990)Trypsin inhibitor content was determined in the seeds of 21 cowpea (Vigna unguiculata) lines (10 known to be resistant to Callosobruchus maculatus and 11 susceptible) whilst fatty acid composition was determined in 58 lines (11 resistant and 47 susceptible). A wide range in trypsin inhibitor contents was observed but these were not related to level of resistance. Total unsaturated fatty acid contents, however, were associated with resistance level, being lowest in the resistant lines. Six fatty ...