Browsing by Subject "West Africa"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Characterization of novel rice germplasm from West Africa and genetic marker associations with rice cooking quality(Texas A&M University, 2006-10-30) Traore, KarimGenetic resource enhancement is the foundation of any good breeding program. Landraces from West Africa, interspecifics between Oryza sativa and Oryza glaberrima and improved lines from the West African Rice Development Association and other research centers were introduced to the Beaumont Rice Research center for in situ evaluation and characterization. Beside the introduction of seeds, milled samples were also introduced for grain chemistry analysis. Field evaluation combined with physicochemical and molecular characterization revealed unique characteristics among African germplasm. New rice for Africa (NERICA) lines performed well in the USA environment. Varieties like Nerica 2, Nerica 3, Nerica 4, and Nerica 5 need more attention because of their superior performance in yield and grain quality. Landraces did not perform well due to their height and late maturity and their resulting problems with lodging. The rapid visco analyzer RVA profiles showed that the cultivar Jaya has unusually strong paste viscosity features. Comparing West Africa samples grown in Cote d??????Ivoire with those grown in Texas, parameters like AA, ASV, Hot, Cool, and CT were not stongly affected by the environment. According to the Stbk value, cultivars grown in Cote d??????Ivoire will cook softer than when they were grown in Texas. The lack of the environmental effect is somewhat surprising considering the difference in latitude, soil types, weather patterns, and management practices between the two locations. Apparent amylose is a key element to characterize a rice cultivar; however certain varieties like Cocodrie and Dixiebelle have similar apparent amylose content but dramatically different functional qualities. A population derived from Cocodrie and Dixiebelle was developed for genotypic and phenotypic analysis of grain chemistry traits that affect functionality. It was concluded that the amount of soluble amylose in the grain had a significant effect on flour pasting properties, even when total apparent amylose content did not vary. Marker association studies revealed that the Waxy microsatellite and the Waxy exon 10 SNP markers were associated with soluble amylose content and RVA characteristics. These markers will speed up the development of new rice cultivars with desirable quality characteristics in West Africa and in the USA.Item Combined effects of global warming and a shutdown of the Atlantic meridional overturning circulation on West African and European climate(2012-05) Brown, Meredith Guenevere Longshore; Cook, Kerry Harrison, 1953-; Fu, Rong; Dickinson, Robert E.; Jackson, Charles S.The Atlantic meridional overturning circulation has a vast potential for abrupt climate change due to its large heat transport through the ocean and its nonlinear dynamics. Because of these unique properties, this paper investigates how the climate of West Africa and Europe will respond to a shutdown of the Atlantic meridional overturning circulation at the end of the 21st century. Here we use a regional climate model with 90-km grid spacing is forced by an idealized sea-surface temperature anomaly, based upon coupled atmosphere/ocean global model water hosing experiments, with a business-as-usual global warming scenario to discover how West African and European climate will change. In both the boreal spring and summer, cooling in the eastern Atlantic is associated with a strong intensification and eastward extension of the North Atlantic subtropical high over Europe throughout the depth of the atmosphere, a strengthening of the heat low over West Africa at low levels, and a weakening of the Saharan High in the upper atmosphere. Rainfall rates also decrease markedly throughout most of West Africa and Europe: in spring, rainfall rates decrease by 50-80% over Sahelian Africa, in summer rainfall over Europe decreases by up to 90%, while precipitation over West Africa is reduced by 40%.Item Soil and Mold Influences on Fe and Zn Concentrations of Sorghum Grain in Mali, West Africa(2012-10-19) Verbree, CherylIron (Fe) and zinc (Zn) deficiencies affect an estimated 3 billion people worldwide and are linked with cognitive and physical impairments, maternal and child mortality rates, and decreased adult work activity. To combat this "hidden" hunger, plant breeders in Mali are working to increase sorghum grain Fe and Zn concentrations. The objective of this study was to investigate soil and mold influences that affect Fe and Zn uptake and accumulation in sorghum grain. In southern Mali, soils from participatory sorghum variety trials and areas of different parent material and proximity to Shea (Vitellaria paradoxa) trees were analyzed for diethylenetriaminepentaacetic acid (DTPA)-extractable Zn and related soil properties, and sorghum grain was analyzed for Zn concentration. An inoculation trial was also performed at College Station, TX to determine if sorghum grain infected by the mold Curvularia lunata significantly increased grain Fe concentrations. DTPA-extractable Zn concentration was highly variable with high concentrations found in soils under Shea tree canopies with high pH and organic carbon and derived from mafic, high Zn-content parent material. However, these high concentrations did not significantly affect grain Zn concentrations in sorghum grown outside of the canopy. Groundnut grown underneath the canopy is likely to be affected and warrants further investigation. In many cases, soil DTPA-extractable Zn concentrations were at deficient levels, thus hampering its correlation to sorghum grain Zn concentration and potentially limiting the expression of genetic Zn biofortification. Knowledge of soil DTPA-extractable Zn concentrations or basic soil properties such as pH, organic carbon, and soil parent material may aid in the location of suitable available Zn fields and overall biofortification efforts. Grain Fe concentration was not significantly related to Curvularia lunata percent recovery or grain mold rating, but instead showed a relatively high variance by panicle, digestion batch, and grain subsample. Additional work is needed to address these sources of Fe variation so as to determine better if mold affects grain Fe concentrations.