Effect of Alternating Temperature on Dark Respiration and 14C Export in Rose Plants

Abstract

Summary The rate of dark respiration of rose plants ( Rosa hybrida cv. Golden Times) measured over a 9 h period was 100% higher at 18 °C than at 12 °C. After the plants had been kept in the dark for 50 h their «main-tenance» respiration at 18 °C was 41 % higher than at 12 °C. However, if the plants were exposed to a repeated alternating temperature regime of 2 h at 18 °C and 2h at 12 °C, their «maintenance» respiration was higher during the high-temperature intervals than at a constant temperature of 18 °C and lower during the low-temperature intervals than at a constant temperature of 12 °C. The proportion of respiration expended on growth was higher under the alternating temperature regime than at either of the constant temperatures. Fluctuations in 14 C export from the leaves of plants exposed to the alternating temperatures corresponded to the fluctuations in the temperature. The total export of 14 C by these plants was similar to that of plants exposed to constant high temperature. In plants exposed to constant low temperature, 14 C export from the leaves was strongly inhibited.