This research was a detailed study of ryegrass (Lolium perenne L.) and the susceptibility to the Drechslera siccans pathogen. It was important to determine whether rapid analytical techniques, applied to the biochemical analysis of L. perenne, could identify and facilitate the removal of susceptible germplasm from the breeding programme. The remaining resistant plants were then positively selected for and used within the further breeding of new cultivars. The study focused upon the standardisation of tire-disease scoring value (OSV) for the O. siccans assessment, and examined the application of near infrared reflectance spectroscopy (NIRS), digital image analysis(DIA), thermogravimetric analysis (TGA) and fourier transformed infrared microscopy (FTIRm). The research aimed to enhance the breeding of new cultivars with greater resistance to D. siccans. Traditional breeding techniques of L. perenne cultivars requires selection and trial examination over many years. This research evaluated germplasm in F2 clonal row trials, which were designed to determine the effect of D. siccans infection. The trial design facilitated the application of rapid assessment techniques in the selection process. Phenotyplc examination of F2 plants resulted in the discovery of a series of differential plants, which had a high level of consistent scoring for DSV, NIRS and DIA, plus using a unique algorithm created the disease assessment tool (OAT). Using OAT a distinct strategy was developed to select L. perenne germplasm, which had consistently high levels of resistance to O. siccans. The TGA and FTIRm research explored the association of macromolecule structure with disease analysis. The TGA result showed a strong positive correlation with WSC analysis of L. perenne (R=0.968) but was unable to determine whether high WSC grass experienced higher susceptibility to D. siccans. Spectrometric analysis of necrotic lesions (caused by O. siccans) using FTIRm identified unique spectra for susceptible L. perenne material. This unique biochemical fingerprint analysis has the potential of quickly identifying susceptible L. perenne with the deselection of F2 plants. This study investigated the selection process of L. perenne germ plasm within a breeding programme, but also included a high level of spectrometric (especially NIRS) and DIA assessment. The assessment strategy developed new L. perenne cultivars these showed a positive outcome for breeding highly productive and more D. siccans resistant L. perenne cultivars. A detailed knowledge was gained for L. perenne phenotypic characteristics and' of the structural biochemistry of the L. perenne. Hence, the product of this research will potentially increase grassland production on farms
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:680868 |
| Date | January 2015 |
| Creators | Archer, John Edward |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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