Articles
HIGH TEMPERATURES AND MARGINALLY INDUCTIVE PHOTOPERIODS IMPACT THE FLORAL DISPLAY OF POINSETTIAS ‘FREEDOM RED’, ‘EARLY RED SPLENDOR’, AND ‘PRESTIGE EARLY RED’
Article number
893_96
Pages
873 – 878
Language
English
Abstract
Commercial production of poinsettias is increasing in low latitude locations where supraoptimal temperatures and marginally inductive photoperiods for poinsettia flowering exist in the fall season.
Presently, we have investigated the impact of these conditions on development of the floral display in three modern, early flowering cultivars (Prestige Early Red, Freedom Red, and Early Red Splendor). Three temperature (21, 24, and 27°C average daily temperature) and photoperiod (11.5, 12.5, and 13.5-h dark) regimes were applied in two separate experiments.
Data collected were the number of days from the end of night interruption lighting through anthesis and the number of bracts per lateral branch on each plant every 10 days.
The hue angle and chroma of a representative colored bract collected from each plant at the time of anthesis was measured with a colorimeter.
In all three cultivars, the number of colored bracts was reduced at 27°C compared with plants grown at 21 or 24°C. The hue angle, a measure of redness, was not significantly different for bracts collected from Freedom Red and Prestige Early Red plants grown with each temperature regime, however the hue angle of bracts collected from Early Red Splendor plants increased from 25 to 71° with a temperature increase of 24 to 27°C. This change corresponds to the presence of more green hues versus red hues in the bracts to the extent that these plants were unmarketable.
With the reduction in dark period length from 13.5 to 12.5-hours dark, the average number of colored bracts per lateral on Early Red Splendor was reduced from 7.3 to 3.3 in contrast to 11.8 to 8.8 in Freedom Red and 9.2 to 8.4 on Prestige Early Red. Plants with less than five colored bracts per lateral were deemed not marketable.
These data indicate that cultivar selection is vital to produce marketable poinsettias in warm, low latitude locations.
Presently, we have investigated the impact of these conditions on development of the floral display in three modern, early flowering cultivars (Prestige Early Red, Freedom Red, and Early Red Splendor). Three temperature (21, 24, and 27°C average daily temperature) and photoperiod (11.5, 12.5, and 13.5-h dark) regimes were applied in two separate experiments.
Data collected were the number of days from the end of night interruption lighting through anthesis and the number of bracts per lateral branch on each plant every 10 days.
The hue angle and chroma of a representative colored bract collected from each plant at the time of anthesis was measured with a colorimeter.
In all three cultivars, the number of colored bracts was reduced at 27°C compared with plants grown at 21 or 24°C. The hue angle, a measure of redness, was not significantly different for bracts collected from Freedom Red and Prestige Early Red plants grown with each temperature regime, however the hue angle of bracts collected from Early Red Splendor plants increased from 25 to 71° with a temperature increase of 24 to 27°C. This change corresponds to the presence of more green hues versus red hues in the bracts to the extent that these plants were unmarketable.
With the reduction in dark period length from 13.5 to 12.5-hours dark, the average number of colored bracts per lateral on Early Red Splendor was reduced from 7.3 to 3.3 in contrast to 11.8 to 8.8 in Freedom Red and 9.2 to 8.4 on Prestige Early Red. Plants with less than five colored bracts per lateral were deemed not marketable.
These data indicate that cultivar selection is vital to produce marketable poinsettias in warm, low latitude locations.
Authors
R.A. Schnelle, J.E. Barrett
Keywords
Euphorbia pulcherrima, flowering, heat delay
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