Types of Photosynthesis: Summary Table of Comparison
of C3, C4, and CAM Photosynthesis

Ben G. Bareja, Aug. 2013

There are three distinct biochemical variants or types of photosynthesis based on the mechanism that plants employ by which carbohydrate is formed from CO2: C3 photosynthesis, C4 photosynthesis, and CAM photosynthesis.


Table TP-1. Summary comparison of C3, C4 and CAM photosynthesis in plants.




FEATURES

C3 PHOTOSYNTHESIS

C4 PHOTOSYNTHESIS

CAM PHOTOSYNTHESIS


Pathway of
CO2 fixation
via C3 cycle only via C3 and C4 cycles, spatially (C4 in the mesophyll cells
followed by C3 in the bundle sheath cells
via C3 and C4 cycles, both spatially (in different parts of same cells) and temporally (C4 at night, C3 at daytime)
Normal
diurnal
occurence

Daytime Daytime Day and night
Initial CO2 acceptor

Ribulose-1,5-bisphosphate (RuBP)

Phosphoenolpyruvate (PEP) PEP at night, RuBP in the day
CO2-fixing enzyme

Ribulose-1,5-bisphosphate carboxylase/
oxygenase (RuBisCo)
Phosphoenolpyruvate carboxylase (PEPcase) then Rubisco PEPcase at night, Rubisco at daytime
First stable product of
CO2 fixation

3-phosphoglycerate (3-PGA) Oxaloacetate (OAA)
in C4 cycle
OAA at night, 3-PGA at daytime
Cells
Involved
Mesophyll cells C4- mesophyll cells, C3- bundle sheath
cells
Both C3 and C4 in same mesophyll cells
Energy
needed for complete reduction
of one
molecule
of CO2

3 ATP, 2 NADPH 5 ATP, 2 NADPH
Environmental conditions favoring most efficient photosynthesis

moderate conditions; temperature
15 °C-25°C
hot, dry conditions; temperature 30°C-47°C extremely dry or xeric conditions; temperature ~35°C
Amount of
water needed
to produce 1 g dry matter

450-950 g 250-350 g 50-55 g
CO2 compensation point 30-70 ppm 0-10 ppm 0-5 ppm
Photorespiration Yes Absent or
suppressed
Absent or
suppressed
Annual dry matter production per hectare

~20-25 tons ~35-40 tons Usually low and variable
Sources: Mathews and Van Holde (1990); Hopkins (1999); Moore et al. (2003); Simpson (2010)


Click on to read more:

/ C3 Photosynthesis / C4 Photosynthesis / CAM Photosynthesis /


< Back to cropsreview.com Crop Farming Homepage from types of photosynthesis