The floriculture and ornamental industry is constantly looking for new products.
South Africa is blessed with an exceptional rich bio-diversity and many South African plants
have found their way onto international markets. The local development of products for the
international market unfortunately is limited. The genus Lachenalia is one of the exceptions,
with local development and production of cultivars for the international pot plant market.
This thesis thus aimed to establish the different aspects and requirements needed for the
development of new Lachenalia cultivars and to use the basic genetic information generated
through research to develop specific breeding strategies for the development of new
cultivars.
The thesis established the wider requirements of the complete value chain for the
development of new floriculture crops and identified the strong need to establish basic
research information in order to successfully develop new cultivars in the genus Lachenalia.
The diversity amongst the 133 described species of Lachenalia and the breeding and
research on production that facilitated the release of cultivars to the international market
indicated the suitability of the genus for development. The genetic variation present in the
genus includes various different basic chromosome numbers, polyploidy, B-chromosomes,
different karyotypes within the same basic chromosome number, different phylogenetic
groups and the existence of possible hybrid species. Relationships between specific basic
chromosome numbers were shown and possible evolutionary history was proposed, but
conclusions in this regard needs further investigation.
The development of new cultivars is possible from both conventional and mutation
breeding processes, but the availability of basic genetic information is essential for future
progress. Inter-specific as well as complex hybrid/hybrid crosses are used for the
development of new cultivars. To facilitate future crosses the cross-ability among
Lachenalia species was investigated. The cross-ability data supports the phylogenetic
relationships identified by various authors and both are strongly linked to basic chromosome
numbers. Phenotypic characters cannot be used to predict the success of inter-species
crosses, except where clear mechanical isolation (female long style species crossed with male short style species) is present.
Clear unilateral cross-ability is present among several species and this is not linked
to self-incompatibility. Self-incompatibility seems to be present in specific species, but can
be overcome by crossing different accessions of the same species. Clear differences in the
level of success of crossing combinations were statistical shown through AHC cluster and
principle component analysis. A limited number of crosses showed good cross-ability with
the production of many normal seeds. Most of these crosses were between species with the
same basic chromosome number with only four exceptions, which were between basic x = 7
and x = 8, confirming the close relationship between these two basic chromosome numbers.
Some intermediate success rates between basic x = 11 with both x = 7 and x = 8 was also
present possible supporting the basal nature of x = 11. Basic chromosome numbers are
currently the best criterion for predicting the success rate of inter-species crossing
combinations but it does not guarantee success.
The data presented clearly indicated the importance of well characterized
(phenotypic and genotypic) germplasm material, including the maintenance of various
accessions of a species. Good breeding parents were identified to assist breeders to reach
specific goals. The importance of an in-depth investigation on the nature and extent of the
crossing barriers and continued research on the genetics and molecular systematic of the
genus was determined. This study clearly shows that the availability of basic genetic
information and data on the cross-ability among species is essential for the selection of
breeding parents to ensure better success rates for inter-species crossing combinations and
the future development of new Lachenalia cultivars.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08202014-114234 |
| Date | 20 August 2014 |
| Creators | Kleynhans, Riana |
| Contributors | Prof JJ Spies |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08202014-114234/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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