TITLE:
The Effect of Photosynthetic Active Radiation and Temperature on Growth and Flowering of Ten Flowering Pot Plant Species
AUTHORS:
Leiv M. Mortensen
KEYWORDS:
Air Temperature, Flowering, Growth, Photon Flux Density (PFD), Photosynthetic Active Radiation (PAR), Pot Plants
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.13,
June
18,
2014
ABSTRACT: Hibiscus rosa-sinensis, Rosa sp. (miniature roses), Sinningia speciosa,
Gerbera hybrida, Kalanchoe blossfeldiana, Hydrangea, Begonia x
hiemalis, Calceolaria, Cyclamen persicum and Pelargonium domesticum were grown
at six photon flux densities (85, 130, 170, 215, 255 and 300 μmol·m-2·s-1,
PFD) during lighting periods of 20 h·day-1 at three air temperatures
(18°C, 21°C and 24°C) in midwinter at latitude 59° north. This corresponded to photosynthetic active radiations (PAR)
ranging from 6.1 to 21.6 mol·m-2·day-1. Time until flowering
decreased in all species except Cyclamen when the temperature increased from 18°C to 21°C, particularly at lower PFD levels. A
further increase in temperature, from 21°C to 24°C, clearly decreased time until flowering in six of the ten tested species. Generally, this represented a reduction in the
time until flowering between 20% and 40%. The dry weight of the plants at time
of flowering increased up to 170 μmol·m-2·s-1 PFD (12.2
mol·m-2·day-1 PAR) in Hibiscus, miniature rose, Kalanchoe
and Pelargonium, while the dry weight reached a maximum at 85 to 130 μmol·m-2·s-1 PFD mol·m-2·day-1 (6.1 to 9.4 mol·m-2·day-1)in the other species. Based on the present results a PAR level of 6 to 8 mol m-2·day-1 is recommended for Calceolaria and Cyclamen, of 8 to 10 mol·m-2·day-1 for Sinningia, Gerbera, Kalanchoe, Hydrangea and Begonia, of 10 to 12 mol·m-2·day-1 for Pelargonium and of 12 to 15 mol·m-2 day-1 for
Hibiscus and miniature roses.