Negash, Legesse (Professor)Edemealem, Addisu2020-11-202023-11-092020-11-202023-11-092018-09-09http://etd.aau.edu.et/handle/123456789/23408Guizotia abyssinica L. f. Cass (synonym Polymnia abyssinica L. f.) belongs to Asteraceae (Compositeae). The species is said to have originated in the Ethiopian highlands and has spread to other parts of the world. In Ethiopia, niger seed is cultivated primarily for valuable edible oil for local consumption. Elsewhere, the crop is used in pharmaceutical products and other industrial applications, and as a green manure for increasing soil organic matter. In reality neither farmers nor extension institutions give focus on using improved practices such as optimum fertilizer applications for niger seed production. The present study was undertaken to find out the effects of chemical fertilizers and compost on growth and yield of G. abyssinica in potted vertisols at Bichena town, West central Ethiopia. A total of 150 plastic bags (depth 20 cm, diameter 10 cm) were filled with 1 kg vertisol, among which 50 bags contained only vertisol, 50 bags contained soils mixed with DAP and urea and the rest 50 contained soils mixed with compost. The study found out that application of DAP and urea at rates of 50 and 30 kg ha respectively improved the vegetative growth by 195 % compared to the control. Similarly, yield increased by 294 . On the other hand, niger plants grown in soils mixed with compost at rates of 12 tons ha improved the vegetative growth by 66% and yield increased by 82 . Though, the analysis of variance showed that there was no significant difference (p < 0.05) among the three treatments for all the germination parameters measured, vertisol mixed with chemical fertilizers (VR + CF) showed the best germination percentage, mean germination time and germination vigor compared to seeds germinated in vertisol mixed with compost (VR + Comp) or in vertisol only. Maximum mean plant height (cm), internodal length (cm), branches/plant, leaf number, leaf area (mm2), RCD (cm), number of capitulae/plant, number of seeds, seeds weight (g), 1000 seeds weight (g) and total dry weight (g) were 73.8, 39.6, 18, 50, 136, 1.8, 19, 355, 0.9, 2.3, and 5.5 respectively for plants grown in VR + CF. The corresponding values for plants grown in VR + Comp were 41.5, 11.9, 7, 26, 43.2, 1.3, 8, 164, 0.5, 2.2, and 1.9 respectively. The control plants resulted in 25, 5.3, 3, 19, 26.2, 1.2, 4, 90, 0.3, 1.8, and 1.2 respectively. Based on the results obtained, it is concluded that application of optimum amount of chemical fertilizers significantly (p < 0.01) improved almost all the growth and yield components of Guizotia abyssinica.enCapitulaeCross-PollinationEdible OilMontmorilloniteNiger SeedThesis