Successful cultivation of sunflower in UK as an oil crop requires the production of early maturing, semi-dwarf. high seed yield and high oil content varieties which must be resistant to the attack by the indigenous pathogens. The present study evaluated a large number of F 1 hybrids produced by utilising cytoplasmic male sterile (CMS) lines of diverse foreign origin and fertility restorer lines developed locally. The two sets of inbred lines of different genetic make-up, derived from the Asmer hybrids and a very early flowering variety S47, have been crossed with the available CMS stocks for their assessment in hybrid combinations. The aim was to produce a wide range of divergent hybrids to make the possible selection of the most suitable lines/hybrids with desirable characteristics. Quantitative methods were used to identify and compare the genetic potentials of the inbred lines and their hybrids among themselves, and to compare their performance with commercial hybrids for some characters of economic interest. The results have been very encouraging and several promising inbreds and crosses have been identified which can be developed into possible varieties for the UK. Genetic analysis of the agronomic characters by the analysis of variance approach has revealed substantial heritable variation in the inbred lines for all the agronomically important characters which partitioned into general and specific combining ability effects and related to the possible types of genes action. Both the additive genetic and the non additive genetic portions arising largely from dominance and epistatic deviations were detected significant. It was revealed that GCA and SCA provide adequate information for making selection when parental lines show a wide range of genetic variability. Combining ability analysis further revealed the predominance of SCA effects and heterosis was detected for all the traits studied. Some yield traits have shown positive heterosis and negative heterosis for flowering time and Sclerotinia sclerotiorum meant that incorporation of earliness and high yield into one genotype is a distinct possibility in this crop. Flowering time and oil content were found to be highly heritable. This result was unusual in the case of flowering time because it was subjected to strong directional selection during the production of inbred lines. Further, heterosis in most characters was caused by directional but partial dominance. The estimates of dominance were found to be rather high in the present study, indicating that hybrids will have a considerable advantage over inbreds as varieties of sunflower. Significant epistasis and dominance for most traits confirmed that the genetic control of variation in sunflower is as complicated as in many other species. A part of the thesis was devoted to the assessment of sunflower families under normal and late sowings. This experiment revealed that early sown material has advantage in most seasons because it matures early, before the onset of autumn. The late sown seeds grow into better quality plants but their yield is affected badly and on many occasions total yield loss can occur when there is high humidity during September. The implications of the present study and those conducted before are discussed at the end and it is concluded that sunflower can prove to be a very useful and profitable crop in the UK provided suitable varieties are made available for cultivation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:626869 |
| Date | January 1995 |
| Creators | Hussain, Tanveer |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0013 seconds