High temperature and drought stress are two of the greatest impediments to bedding plant growth and development. The objective of this study was to develop a rapid and effective protocol for screening Petunia x hybrida for basal heat or drought tolerance. A practical growth system for measuring seedling growth, or seedling growth sensitivity test (SGST), was first established. Based on this protocol, radicle growth rate was chosen over hypocotyl growth as the most reliable and accurate measurement for the SGST. Nineteen petunia cultivars from three plant classes (floribunda, grandiflora, or spreading) were previously evaluated, where cultivars within the same plant class and series were grouped as either best or worst for overall landscape performance, and then subjected to the SGST. Seeds were germinated in Petri dishes at 26°C for 4 days and then subjected to 5-h heat shock at a temperature of 40°C or 6 d drought stress at an osmotic potential of -0.8MPa achieved with PEG 6000 to determine heat or drought tolerance, respectively. The results indicated heat or drought stress significantly affected the relative radicle growth rate of seedlings. However, the imposed stress did not affect all cultivars similarly. While Avalanche Lilac and Dreams Burgundy Picotee had the greatest radicle growth rate, they were considered as more heat susceptible cultivars due to a significant reduction in radicle growth rate under heat stress. Avalanche Lilac was also regarded as the most drought sensitive cultivar. The results from this study indicate that the SGST may be used to determine heat or drought tolerance, but further research should be conducted to determine greenhouse and landscape performance under heat or drought stress.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-04132009-122420 |
| Date | 13 April 2009 |
| Creators | Liu, Miao |
| Contributors | Jeff S. Kuehny, Jeffrey S. Beasley, Marc A. Cohn |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-04132009-122420/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein 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 LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, 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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