Evidence for Photorespiration in Tropical Grasses

Sugarcane leaves respired in full light and the CO2 evolved could be detected in sorghum or miaze photosynthesizing in the same closed system. A combination of radiometric and infra‐red gas analysis techniques allowed the estimation of photorespiration (total CO2 evolution in light) and photosynthesis at increasing light intensities and of dark respiration. Rates of CO2 evolution approaching those of temperate zone plants occurred at lower light intensities but rapidly decreased with higher light. Smaller but significant quantities of 14CO2 were released even at intensities approximating full sunlight in leaves of maize, sorghum and sugarcane. Highly efficient CO2 capture may explain the low rates of photorespiration at high light intensities.