THE EFFECTS OF LOW GROWTH AND MEASUREMENT TEMPERATURE ON THE RESPIRATORY PROPERTIES OF 5 TEMPERATE SPECIES

Five temperate ruderal species, Epilobium glandulosum, Matricaria matricariodes, Melilotus alba, Sonchus asper and Taraxacum officinale, were grown under controlled conditions at both 10 °C and 20 °C. Respiration was measured at 10 °C and 20 °C. Total dark respiration rates of plants grown at 10 °C were consistently higher than the rates of plants grown at 20 °C. This was due to greater respiratory activity along both the cytochrome (KCN-sensitive) and alternative (SHAM-sensitive) pathways in the cold grown plants. The capacity to use the alternative pathway was also greater in the 10 °C grown plants. The increase in the relative contribution of each pathway was species specific. At a given growth temperature the activity of the alternative pathway varied little between measurements at 10 °C and 20 °C. In contrast, the activity of the cytochrome pathway was greater when measured at 20 °C than when it was measured at 10 °C. The capacity of the alternative pathway was lower when measured at 10 °C. These results suggest that the cytochrome pathway is more sensitive to temperature stress than is the alternative pathway. © 1990 Annals of Botany Company.