|Authors: ||J.L. Catley, I.R. Brooking, L.J. Davies, E.A. Halligan|
|Keywords: ||flower quality, growth, irradiance, Sandersonia aurantiaca|
The influences of temperature and irradiance on the time of flower initiation, sprouting, growth and flowering of Sandersonia aurantiaca were examined in a series of controlled environment studies.
Plants were grown at constant temperatures of 15, 18, 21, 24 or 27oC; or at a mean temperature of 21oC with day/night differentials of –6, 0, +6, +12 or +18oC. Photosynthetic photon flux densities (PPF) were either 210, 460 or 700 μmol m-2 s-1 for 12 hours with photoperiod extension of
8 μmol m-2 s-1 for 2 hours.
Flower initiation commenced after 62 days of sprouting at 12oC, 30 days at 18oC, and 22 days at 24oC. At all temperatures, flower initiation had commenced before shoot emergence from the soil. Flower numbers per stem increased with sprouting temperature, growing temperature and irradiance.
Under differential temperatures, the greatest number of flowers were produced at differentials of 0, +6 and +12oC. However, the most desirable shaped flowers were grown at lower constant temperatures or smaller deviations in daily temperature.
Stem length increased as constant growing temperatures increased to 24oC and as the day/night differentials increased from –6 to +12oC. In all cases, stem length decreased as irradiance increased.
However, stem strength was in general inversely related to stem length, so that the strongest self-supporting stems were produced under combinations of lower temperature and higher irradiance.
The number of days to flowering decreased as temperature increased.
Under the day/night differential growing regimes, plants flowered quickest in the control temperature of a constant 21oC (0oC differential).
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