Interaction of red to far red light ratio and ethylene in regulating stem elongation of <Emphasis Type="Italic">Helianthus annuus</Emphasis> |
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Authors: | Leonid V Kurepin Linda J Walton David M Reid |
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Institution: | (1) Department of Biological Sciences, University of Calgary, University Drive 2500 NW, Calgary, Alberta, Canada, T2N 1N4 |
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Abstract: | Sunflower (Helianthus annuus L.) stems showed increased elongation under two types of vegetative shade: canopy shade (low red to far red R/FR] ratio)
and neighbouring proximity shade (FR enrichment). Hypocotyls also elongated more under narrow-band FR light than under narrow-band
R light. Ethylene levels were determined in actively elongating 7-day-old hypocotyls and 17-day-old internodes under three
R/FR ratios. Ethylene levels were lower in both sunflower hypocotyls and internodes when the R/FR ratio was reduced. Both
FR enrichment of normal R/FR ratio and narrow-band FR light with very low light irradiance resulted in reduction in ethylene
levels in 7-day-old hypocotyls. Further, in application experiments, sunflower stems grown under low R/FR ratio were more
sensitive to ethephon and less sensitive to aminoethoxyvinylglycine (AVG) than stems grown under high R/FR ratio. Low R/FR
ratio appears to initiate reduction in ethylene levels in sunflower seedlings, allowing maximum stem elongation. These results,
and findings of other authors, suggest that various plant species may have developed different ways of regulating stem elongation
and ethylene levels in response to low R/FR ratio. |
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Keywords: | Ethylene Light quality Narrow-band light Stem elongation |
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