C3 and C4 Pathway Differences

C3 plants are those that use the Calvin cycle in the dark reaction stage of photosynthesis, whilst C4 plants use the Hatch-Slack Pathway.

C4 plants are less efficient than C3 plants at fixing CO2 in temperate climates and are also more sensitive to shade conditions.

C4 plants grow faster and are more energy efficient in the fixing of carbon, as well as having a better efficiency of water usage, than C3 plants.

Feature C3 plants C4 plants
Location Temperate, cooler, moist climates Tropical, warmer, drier climates
Global (green) plant species 95% 5%
Photosynthesis Occurs when stomata open Occurs when stomata open or closed
First product of photosynthesis 3-carbon acid (phosphoglyceric acid) 4-carbon acid (oxaloacetate)
Krantz anatomy Not present Present
Carbon fixation Occurs once Occurs twice (due to Krantz anatomy)
Photorespiration Can be high Does not occur
Typical ‘optimum’ turfgrass growing temperatures, Celsius * c. 16.5 to 24 c. 26.5 to 35
Minimum soil temperature (Celsius) for growth* c. 4.5 c. 16
*[The range will vary depending on species and cultivars]