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. & 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 degrees C) to dry and warm (22-24 degrees C). The optimum temperature for photosynthesis was 23.7-25.6 degrees C for C. australe and 21.2-24.6 degrees C for F. brayleyana. Mean maximum rate of electron transport for each species did not differ between sites but was higher (60-62 &mgr;mol m(-2) s(-1)) in F. brayleyana than in C. australe (42-44 &mgr;mol m(..