Energy metabolism of the thermogenic tropical water lily, Victoria cruziana

Energy turnover in the giant water lily, Victoria cruziana was determined by indirect calorimetry (oxygen consumption rate) and different kinds of thermometry. Experiments were performed in a greenhouse pond of the Botanical Gardens, Free University of Berlin, Germany at constant water and air temperatures (30 and 24 °C, respectively). Flowers were investigated (i) in situ as a whole floating on the water or elevated a few centimeter above its surface, and (ii) in vitro after cutting and transporting to the laboratory: (a) as a whole or (b) dissected into their single components. Buds and flowers have heat production rates between 1 and 9 mW g−1 wet weight, depending on their state of blooming. Results show that plant structures which are near to the floral chamber exhibit high metabolic rates and temperatures raised by about 10 K compared with outer parts like sepals. Continuous temperature monitoring reveals a time course with two heat dissipation maxima in the first evening/night and the afternoon of the second day of blooming. Growth of leaves is briefly touched.