Genetic and Root Growth Studies in Cassava (Manihot esculenta Crantz): Implications for Breeding

Simple item page
dc.contributor.authorKizito, Elizabeth B.
dc.date.accessioned2017-12-15T10:45:01Z
dc.date.available2017-12-15T10:45:01Z
dc.date.issued2006
dc.descriptionThis thesis was submitted for the degree of Doctor of Philosophy in the Department of Plant Biology and Forest Genetics, Faculty of Natural Resources and Agricultural Sciences. Swedish University of Agricultural Sciences Uppsala 2006en_US
dc.description.abstractCassava (Manihot esculenta Crantz) is a perennial tropical crop grown for its starchcontaining tuberous roots. It is cultivated mainly by small-scale farmers and consumed daily by an estimated 500 million people. Cassava mosaic disease (CMD) has long been recognized as a major limiting factor to cassava production in Africa and severe epidemics hit Uganda in the late 1920’s and late 1980’s. In spite of its importance as a major food crop it is the least researched major crop and many questions regarding its genetics are still unresolved. This thesis has therefore dealt with studies on: i) the effect of CMD on the genetic diversity of cassava in Uganda, ii) the composition of varieties and the genetic structure within and between varieties on small farms in Uganda, iii) the genetic basis of two agronomic important traits, cyanogenic glucoside potential (CNP) and dry matter content (DMC) in cassava roots, using quantitative trait loci (QTL) mapping and iv) the effect of nutrient availability on the growth and tuber formation. The outcome of these studies is relevant for developing strategies for breeding and gene conservation programmes. CMD did not have a strong selective effect on the genetic diversity of cassava in Uganda in spite of earlier reports on losses of varieties due to the latest CMD epidemic. However, a loss of rare alleles in areas with high CMD incidence in Uganda was found. The composition of varieties differed widely between villages and districts and the genetic variation was surprisingly large within varieties although the variation was larger among varieties. The like-named varieties in different villages were genetically similar, demonstrating farmers’ ability to differentiate and maintain the same variety over large areas. We detected two QTL on two different linkage groups controlling CNP and six QTL on four different linkage groups controlling DMC. One QTL for CNP and one QTL for DMC mapped near each other, suggesting pleiotrophy or linkage of QTL. In the root studies, production of storage roots was found to be regulated by nutrient availability and appeared to be positively affected by a gradually increasing limitation of mineral nutrients during the growth of the plants.en_US
dc.identifier.citationKizito, Elizabeth Balyejusa (2006). Genetic and Root Growth Studies in Cassava. PhD thesis, Dept. of Plant Biology and Forest Genetics, The Swedish University of Agricultural Sciences Uppsalaen_US
dc.identifier.isbn91-567-7131-1
dc.identifier.issn1652-6880
dc.identifier.urihttps://hdl.handle.net/20.500.11951/80
dc.language.isoenen_US
dc.publisherSwedish University of Agricultural Sciences Uppsalaen_US
dc.subjectCassava: the biology, ecology and origin of the planten_US
dc.subjectCassava in Africa and Asiaen_US
dc.subjectGenetic diversity of cassavaen_US
dc.subjectCassava breedingen_US
dc.titleGenetic and Root Growth Studies in Cassava (Manihot esculenta Crantz): Implications for Breedingen_US
dc.typePhD Thesisen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Kizito_Genetic and root growth studies in cassava_PhD_Thesis_2006.pdf
Size:
4.62 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Theses from other institutions by UCU staff members