Čeština
EnglishImpact of end-of-day red and far-red light on plant morphology and hormone physiology of poinsettia
Islam M.A., Tarkowská D., Clark J.L., Blystad D.-R., Gislerøda H.R., Torrea S., Olsen J.E.
SCIENTIA HORTICULTURAE 174: 77-86, 2014
Keywords: Abscisic acid, End of day far red light, End of day red light, Gibberellin, Indole-3-acetic acid, Shoot elongation
Abstract: Control of morphology is essential in greenhouse production of poinsettia, which is among the largest and economically most important ornamental pot plant cultures worldwide. Plant growth regulators are used to reduce shoot elongation but due to their potentially negative impacts on human health and the environment, it is highly desirable to replace these. Exploiting responses to light quality as an alternative has been investigated to a limited extent only in poinsettia and information about elongation-controlling hormones is scarce. In natural light an increased far-red (FR) proportion at the end of the day (EOD) is known to enhance shoot elongation in several species through action of phytochrome on hormone metabolism. The aim of this study was to assess the effect of manipulation of the phytochrome systemat the EOD on elongation growth and hormone metabolism in poinsettia. Depending on cultivar, shoot elongation and internode lengths were reduced 34–54% by exposure to 30 min EOD-R compared to 30 min EOD-FR, both provided by light emitting diodes. The reduced elongation under EOD-R correlated with29% and 21% lower levels of gibberellin and indole-3-acetic acid, respectively. Specific leaf and bractarea were also significantly lower under EOD-R compared to EOD-FR. Bract formation and time to visible cyathia did not differ between the light treatments. In conclusion, manipulation of the phytochrome system by EOD-R in order to modulate the contents of the growth-controlling hormones can be a usefultool in control of shoot elongation in greenhouse-grown poinsettia in order to counteract the effect ofthe increased FR proportion at the EOD.
DOI: IEB authors: Danuše Tarkowská
SCIENTIA HORTICULTURAE 174: 77-86, 2014
Keywords: Abscisic acid, End of day far red light, End of day red light, Gibberellin, Indole-3-acetic acid, Shoot elongation
Abstract: Control of morphology is essential in greenhouse production of poinsettia, which is among the largest and economically most important ornamental pot plant cultures worldwide. Plant growth regulators are used to reduce shoot elongation but due to their potentially negative impacts on human health and the environment, it is highly desirable to replace these. Exploiting responses to light quality as an alternative has been investigated to a limited extent only in poinsettia and information about elongation-controlling hormones is scarce. In natural light an increased far-red (FR) proportion at the end of the day (EOD) is known to enhance shoot elongation in several species through action of phytochrome on hormone metabolism. The aim of this study was to assess the effect of manipulation of the phytochrome systemat the EOD on elongation growth and hormone metabolism in poinsettia. Depending on cultivar, shoot elongation and internode lengths were reduced 34–54% by exposure to 30 min EOD-R compared to 30 min EOD-FR, both provided by light emitting diodes. The reduced elongation under EOD-R correlated with29% and 21% lower levels of gibberellin and indole-3-acetic acid, respectively. Specific leaf and bractarea were also significantly lower under EOD-R compared to EOD-FR. Bract formation and time to visible cyathia did not differ between the light treatments. In conclusion, manipulation of the phytochrome system by EOD-R in order to modulate the contents of the growth-controlling hormones can be a usefultool in control of shoot elongation in greenhouse-grown poinsettia in order to counteract the effect ofthe increased FR proportion at the EOD.
DOI: IEB authors: Danuše Tarkowská