Asfaw Zemede (Professor)Tilahun Mulugeta2018-07-182023-11-092018-07-182023-11-092017-05http://etd.aau.edu.et/handle/123456789/9290Ethiopian farmers have been traditionally growing several varietal mixtures in the same field that might have advantages of reducing the risks of pests and unusual environmental conditions in addition to adding variety to their diets. Replacement of farmers’ varieties with genetically uniform varieties, results in changes to crop patterns and land uses largely affecting the magnitude of the genetic diversity in Ethiopian tetraploid wheats. Therefore, this study was conducted at two locations of each Amhara, Oromia and Tigray regions with the objective of evaluating the effects of mixtures of Ethiopian tetraploid wheat collections on agronomic and nutritional quality traits and maintaining the diversity of the crop. The experiment was laid out by using alpha lattice design with three replications. The experiment had fifteen genotypes with two categories (Category one: mixtures and pure stands of Ethiopian tetraploid wheat collections and Category two: mixtures and pure stands of improved varieties). Agronomic and proximate as well as selected minerals data were taken and subjected to analysis using SAS procedures. Since genotype by location interaction was significant for agronomic traits, analysis was conducted for each locations and GGE-biplot was used to select best fit genotypes for each location. The analysis of variance showed significant differences for both agronomic and nutritional quality traits. The range of grain yield was 0.2 to 2.7tha-1 in Adet, 1.5 to 2.6tha-1 in Geregera, 0.6 to 3.0tha-1 in Debre Zeit, 2.4 to 3.4tha-1 in Chefe Donsa, 1.4 to 2.6tha-1 in Ayiba and 2.8 to 3.8tha-1 in Hagereselam. Based on the analysis of individual locations and GGE-biplot mega environment results; mixtures of top ten Amhara Region, mixtures of ten improved varieties, Assasa and Mikuye are best genotypes for Adet and Geregera of Amhara Region. Mixtures of Oromia Region, GEBRE of Oromia Region, Assasa and Mikuye are best genotypes for Debrezeit and Chefe Donsa of Oromia Region. Whereas mixtures of top ten Tigray Region, GG2 of Tigray Region, GEBRE of Oromia Region and Mangudo are best genotypes for Ayiba and Hagereselam of Tigray Region. In regarding to nutritional quality, amounts ranged from 8.1 to 13.0% for protein, 73 to 78.9%for total carbohydrate, 1.4 to 2.9% for fat, 2.5 to 3.4% for fiber, 1.1 to 3.4gm/100gm for Fe and 1.9 to 2.7gm/100gm for Zn. Significantly higher protein contents (13.0 and 11.9%) were recorded from Mangudo, mixtures of Tigray Region and TIKUR SINDE of Amhara Region. Maximum total carbohydrate (78.9%) was obtained from GEBRE of Oromia Region. Higher fat contents (2.9, 2.6 and 2.5%) were obtained from TIKUR SINDE of Amhara Region, mixtures of top ten Tigray Region and Mangudo respectively. Maximum Fe 3.4 mg/100gm and Zn (2.7 mg/100gm) were obtained from mixtures of parental lines. Therefore, it can be concluded that mixtures as well as pure lines of farmers’ varieties performed well comparatively with pure lines of high yielding improved varieties in this experiment and farmers can maintain the diversity of the crop and add supplement their diets by growing mixtures of Ethiopian tetraploid wheat genotypes. Key words: Diversity maintenance, farmers’ varieties, GGE-biplot, mega environmentenDiversity maintenanceFarmers’ varietiesGGE-biplotMega environmentThesis