AOBPreview published online on May 9, 2005
Annals of Botany, doi:10.1093/aob/mci157
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1 Laboratoire d'Evolution et Diversité Biologique, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
* To whom correspondence should be addressed.
• Backgrounds and Aims Thermogenesis in reproductive organs is known from several plant families, including the Araceae. A study was made of the relationship between temperature increase and spadix size in the subfamily Aroideae in order to determine whether the quantitative variation of heat production among species and inflorescences of different sizes follows a physical law of heat transfer. • Methods Spadix temperature was measured in 18 species from eight genera of tropical Araceae from the basal clade of Aroideae, both in French Guiana and in the glasshouses of the Montreal Botanical Garden. • Key Results A significant logarithmic relationship was found between the volume of the thermogenic spadix zone and the maximum temperature difference between the spadix and ambient air. Four heat transfer models were applied to the data (conductive heat transfer alone, convective heat transfer alone, radiative heat transfer alone, and convective and radiative heat transfers) to test if physical (geometric and thermic) constraints apply. Which heat transfer model was the most probable was determined by using the criterion of a classical minimization process represented by the least-squares method. Two heat transfer models appeared to fit the data well and were equivalent: conductive heat transfer alone, and convective plus radiative heat transfers. • Conclusions The increase in the temperature difference between the spadix and ambient air appears to be physically constrained and corresponds to the value of a thermal model of heat conduction in an insulated cylinder with an internal heat source. In the models, a heat metabolic rate of 29.5 mW g-1 was used, which was an acceptable value for an overall metabolic heat rate in aroid inflorescences.
Received August 11, 2004
Revised November 15, 2004
Accepted March 9, 2005
Article
Physical Constraints on Temperature Difference in Some Thermogenic Aroid Inflorescences
2 Institut de Recherche en Biologie Végétale, Université de Montréal, Jardin Botanique de Montréal, 4101 Rue Sherbrooke Est, Montréal (Québec), Canada H1X 2B2
3 Laboratoire des Matériaux et Durabilité des Constructions, Institut National des Sciences Appliquées/Université Paul Sabatier, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France
4 Laboratoire d'Energétique, Université Paul Sabatier, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France
MARC GIBERNAU, E-mail: gibernau{at}cict.fr
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