The analysis of patterns of leaf and canopy photosynthesis in relation to crop development will provide essential information to understand carbon partitioning and development of the yield. Studies attempting to determine these physiological parameters in field-grown plants are often confounded because environmental and management variables co-limit growth and photosynthetic processes.

The objective of this study was to determine canopy and leaf photosynthesis and related physiological parameters under controlled environmental conditions as a function of leaf and canopy aging. Experiment 1 was conducted to determine leaf photosynthesis and related physiological processes when plants were grown under optimal temperature (30/22°C), water and nutrient conditions. Experiment 2 was designed to understand the limitations of canopy photosynthesis under nitrogen-sufficient and nitrogen-deficient conditions when plants were grown under optimal temperature and water conditions. Experiment 3 was designed to understand the limitations of diurnally and seasonally varying temperatures and different levels of carbon nutrition on canopy photosynthesis when water and other nutrients were provided adequately.