Methyl bromide fumigation, a common method used to combat soil borne pathogens in commercial tomato cultivation, was to be limited by the Montreal Protocol due to concerns of ozone depletion. Alternative methods to protect tomatoes against diseases include grafting. However, short grafted transplants may expose the scion to the soil. To avoid scion exposure, hypocotyl elongation of two tomato rootstocks 'Maxifort' and 'Aloha' via end-of-day far-red (EOD-FR) was examined in terms of light quality (red to far-red ratio, or R/FR) and dose (product of far-red intensity and duration). In EOD-FR light quality experiments, 'Aloha' seedlings were exposed to unfiltered and filtered incandescent light with an R/FR of 0.5 and 0.05 respectively. The resulting hypocotyl elongation was higher in filtered light than either the unfiltered light or the untreated control. Hypocotyl elongation response to EOD-FR dose in 'Aloha' and 'Maxifort' was affected by both far-red intensity and treatment duration. A saturating response was also found within a far-red dose between 0–8 mmol•m⁻²•d⁻¹ and modeled using non-linear regression with a three parameter Michaelis-Menten equation to estimate the far-red dose required to obtain near-maximum hypocotyl elongation for 'Aloha' and 'Maxifort'. The far-red dose required was affected by cultivar and experimental period. None of the EOD-FR treatments affected plant mass or stem diameter. To conclude, for maximum hypocotyl elongation using EOD-FR, the lower R/FR would increase the effectiveness of the treatment. The far-red dose should preferably be at 4–8 mmol• m⁻²•d⁻¹.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/193454 |
| Date | January 2009 |
| Creators | Chia, Po-Lung |
| Contributors | Kubota, Chieri, Kubota, Chieri, Ray, Dennis T, Wang, Guangyao |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Electronic Thesis |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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