Photosynthetic characteristics of Flindersia brayleyana and Castanospermum australe from tropical lowland and upland sites

Abstract

Photosynthetic responses to temperature, light and carbon dioxide partial pressure were studied in two-year-old Flindersia brayleyana F. Muell. and Castanospermum australe Cunn. and C. Fraser ex Hook. growing on coastal lowland and upland rainforest sites in tropical Queensland, Australia. Climatic conditions ranged from moist and cool (17-19 °C) to dry and warm (22-24 °C). The optimum temperature for photosynthesis was 23.7-25.6 °C for C. australe and 21.2-24.6 °C for F. brayleyana. Mean maximum rate of electron transport for each species did not differ between sites but was higher (60-62 μmol m-2 s-1) in F. brayleyana than in C. australe (42-44 μmol m-2 s-1). Ribulose-bisphosphate carboxyl..