Njuguna, Wambui (2005) Characterization of Kenyan Sweetpotato [Ipomoea balalas (L.) Lam] Germplasm Using Morphological and Molecular Markers. Masters thesis, Kenyatta University.
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PDF (Characterization of Kenyan Sweetpotato [Ipomoea balalas (L.) Lam] Germplasm Using Morphological and Molecular Markers)
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Abstract
East Africa is the largest producer of Sweet potato in Africa with Uganda taking the lead. Sweet potato has higher genetic diversity than other root crops such as cassava, yams or coco yams. The short tropical day lengths found in East Africa favours Sweet potato flowering leading to hybridisation and giving rise to new varieties. In addition, the nature of its dispersal and vegetative propagation has created a vast number of cultivated genotypes. Conservation of this germplasm is necessary for the improvement of agricultural production. Characterization of germplasm is the first step in establishing a core collection, which promotes easier management of the genetic diversity. In the present study, morphological characterization was done to eliminate the duplicates in the Sweet potato collection. Principle Component Analysis (PCA) was done to determine the descriptor that contributed the highest variation while DIY A-GIS version 4.2, a Geographical Information Systems software was used to analyse the Sweet potato collections with regard to their geographical locations. Four hundred and eighty three varieties were identified as unique varieties, while there were one hundred and fifty seven duplicates in the collection using a sorting method. There were also some varieties that were initially identified as "unknown" because they did not have local names. Some of these were identified because they formed duplicates with some of the known varieties. The descriptor, Shape of Central Leaf Lobe was found to have the highest influence in discriminating among the varieties. In the present study morphological and ISSR (Inter Simple Sequence Repeats) profiles for twenty-two most popular farmer varieties of Sweet potato in Kenya were generated. Both techniques identified the different varieties as unique. However ISSR gave low variation as compared to morphological markers from the bootstrap values calculated for the trees generated. The morphological markers separated the twenty-two varieties into five groups each having a different shape of Central Leaf Lobe. Farmer varieties are the greatest source of genetic variation and therefore need to be conserved and used in breeding. It has been noted that even when improved cultivars are readily available, farmers continue to rely on landraces because of lack of economic and institutional resources to suit the requirements of modem cultivars. Introduction of new varieties into smallholder cropping systems can lead to rapid loss of valuable traditional varieties. Continued erosion of germplasm indicates the need to secure long-term preservation of landraces.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | Q Science > QD Chemistry Q Science > QK Botany S Agriculture > S Agriculture (General) |
| Divisions: | Africana |
| Depositing User: | Tim Khabala |
| Date Deposited: | 19 Jan 2018 14:20 |
| Last Modified: | 19 Jan 2018 14:20 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/3116 |
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