Microcalorimetry: a Novel Approach to Decision Making in Cut Rose Production

Since its innovative use by Lavoisier at the end of the eighteen-century, calorimetry has been one of the most important foundations of modern science. However, only recently, with the advent of modern and accurate sensors, has it to play a central role in the life sciences. The combination of calorimetric and respirometric studies resulted in a thermodynamic model that represents the rate of storage of chemical energy in structural biomass or Specific Growth Rate (RSG) that serves as an indicator for potential growth rate (PGR) of the tested tissue. Simultaneous measurements of metabolic heat rate (q) and respiratory heat production (RCO2) at the relevant range of environmental conditions such as temperature provides an insight into plant’s response to these factors and allow us to define their optimal range. The actual measurement is destructive in nature but with microcalorimetry only a small amount of plant tissue (2-3 mg DM) is required for each observation. This report demonstrates the use of calorespirometric analyses for two processes, using Rosa x hybrida ‘Kardinal’: • RSG as a function of temperature of young rose leaflets and sprouting axillary buds. • RSG as a function of moisture tension of young rose leaflets. Optimal temperature for young leaflets was found to be 25°C while that of young buds was below 15°C. Optimal temperature control in rose greenhouses is discussed in view of these results. The effect of physical characteristics of the root zone, such as moisture tension and unsaturated hydraulic conductivity K(h) on (Specific Growth Rate) RSG of young leaflets was evaluated at the optimal temperature. It was found that the higher the tension, the lower was the RSG. However, based on comparing the physical properties of 2 different media: UC mix and coir, it can be assumed that at high moisture tension, K(h) is more effective than moisture tension per se in moderating RSG.