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Title: Flowering Induction and Cross Compatibility Studies for Sweetpotato (Ipomoea batatas, L.) Breeding
Authors: Samba, Jebeh Augusta
Issue Date: 16-Dec-2013
Abstract: Lack of flowering in some sweetpotato genotypes, and the existence of incompatibilities among them, do present challenges to sweetpotato breeding programmes. To address these in the breeding programmes at CSIR-CRI, flowering induction and cross compatibility studies for sweetpotato breeding were undertaken. Eight sweetpotato varieties; Faara, Sauti, Ogyefo, Apomuden, Hi-Starch, Otoo, Santom Pona, Okumkom and CIP 440390 were used in reciprocal crosses in the first study to determine cross compatibility groups in the Ghanaian crossing block. The varieties Ogyefo,Sauti, Faara,Ipomoea nil-cv. Kidachi Asagao and Ipomoea setosa Ker. Gawl.were used in the second study of flowering induction, where in Faara, Ipomoea nil and Ipomoea setosawere used as rootstocks.Ogyefo and Sauti were used as scions in the grafting. The first study was conducted in the field and the second study was conducted in both the screenhouse and field. Data to evaluate the success rate of crosses based on the different cross combinations, on time of day, and month of the year the crosses were made, were obtained from crossing to seed production for all the cross combination groups in the compatibility study and data were obtained from graft establishment to flowering for all graft combinations in the flower induction study. All cross combinations made among the Ghanaian sweetpotato cultivars were compatible. Assessment of the number of seeds produced per cross suggests that the crosses;Faara x Apomuden, Apomuden x Faara, Faara x Otoo, Otoo x Faara and Santom Pona x Faara were the most compatible among the seed parents. And the best time of day for hybridization was between 6-7a.m. and 7-8a.m. Seed set was highest in August perhaps due to favourable weather condition for hybridization when; the average minimum temperature was 24.0˚C, maximum temperature, 26.7˚C and relative humidity 86.7%. In the flower induction experiment graft combinations in the field performed far better in flower production thanthose in the screenhouse. Among the rootstocks, I.nil proved to be the most effective in flower induction, followed byI.setosa,while Sauti was the best scion plant in the study. Flowering from the different graft combinations started slowly and increased as the time advanced from the first day to the thirty-fourth day of flowering. Afterwards, all the graft combinations in the field were dead and those in the screenhouse stopped flowering, perhaps due to the harsh weather conditions.
Description: A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirement for the award of Master of Science degree in Plant Breeding, August-2013
URI: http://hdl.handle.net/123456789/5403
Appears in Collections:College of Agric and Natural Resources

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