Energy Loss in Tissue 2Sauromatum guttatum (Schott) Analysed by Microcalorimetry

The heat evolved by 1 mm-thick tissue slices of the appendix of the Sauromatum guttatum inflorescence was measured calorimetrically during development. From D–5 (5 d before inflorescence-opening, designated as D-day) to D–2 about 8 μW mg−1 fresh wt. was observed, and during D–1 an increase in heat evolution to 14 μW mg−1 fresh wt. was monitored. The heat was produced through oxidative metabolism, since replacing the air in the microcalorimeter with nitrogen blocked heatproduction. Addition of salicylic acid to tissue slices of thermogenic organs (appendix, lowest part of the spadix and male flowers) and of non-thermogenic organs (female flowers, club-shaped organs and lower part of the spadix) of Sauromatum inflorescences revealed that the acid boosted heat-production only in the thermogenic organs. The effect of the acid manifested itself with no appreciable lag time, and it generated non-linearity in the rate of heat-production by tissue slices of the appendix. In the appendices of the highly thermogenic Arum italicum and of the weakly thermogenic Amorphophallus rivieri, salicylic acid selectively boosted the rate of heat-production in the appendix of A. italicum. A Q10 of 2·4 was found between 15°C to 25 °C for 1 mm-thick slices of D–4 appendices of S guttatum. Addition of digitonin or deoxycholate to pre-D-day tissue slices of the appendix increased the rate of heat-production.