Monday, April 23, 2012

C3 Plants

I was reading Ohio's Country Journal and came across this note about C3 and C4 plants. I thought what the heck? and looked it up. They started teaching this AFTER I got my Master's Degree.

Soybeans are C3 plants. This means they assimilate carbon differently than other types of plants like wheat or corn.

"The three types of photosynthesis are C3, C4, and CAM. C3 photosynthesis is the typical photosynthesis the most plants use and that everyone learns about in school (it was all we knew about until a few decades ago). C4 and CAM photosynthesis are both adaptations to arid conditions because they result in better water use efficiency. In addition, CAM plants can "idle," saving precious energy and water during harsh times, and C4 plants can photosynthesize faster under the desert's high heat and light conditions than C3 plants because they use an extra biochemical pathway and special anatomy to reduce photorespiration. Below are the details.

C3 Photosynthesis : C3 plants.

Called C3 because the CO2 is first incorporated into a 3-carbon compound.
Stomata are open during the day.
RUBISCO, the enzyme involved in photosynthesis, is also the enzyme involved in the uptake of CO2.
Photosynthesis takes place throughout the leaf.
Adaptive Value: more efficient than C4 and CAM plants under cool and moist conditions and under normal light because requires less machinery (fewer enzymes and no specialized anatomy)..
Most plants are C3."

My friend Kelly said, "The biggest thing I got out of C3 C4 was in weed control and why things yield the way they do…….

A C3 crop like soys cant compete against a C4 weed when its hot and the C3 “stops growing” for lack of a better word. In other words, I know waterhemp is a C4 so when it gets hot and a C3 stops growing because its to hot to photosynthesize I had better be spraying my fields for waterhemp if they are there because in a matter of days they will take away the water, nutrients and also outgrow the soys……….

Best example of how I use it………."

See, I learned something new from a farm paper! I had to research it and ask me network about it first though...

Have a great day! Where did that nice weather go? It's snowing not that far east of here!

I will see if I can post a picture of Liam with his new C3 plant. Whoops, he got waylaid by an excavator.



  1. "Some generalities as I was taught in forage ruminant relations:

    C4 forages: typically tropical origin, high cell wall content, low protein, high lignin, plant storage polysaccaride is starch. Warm season forages.

    C3 forages: typically temperate origin, low cell wall content, high protein, low lignin, plant storage polysaccaride is sugars. Cool season forages.

    There is an appreciable non-structural carbohydrate fraction in soy leaf...say 20% and low ndf and high protein...c3 warm season imo based on composition."

  2. Hi Ed. In our summer cover crop mixes, do you think the C3 or C4 nature of plants should not have a bearing on our choices for the mix? For example, I can still include soy for diversity, but expect it to be suppressed by the c4 grasses. I'm thinking the time of sowing nor the sowing rates will be affected by the photosyn. type either. Is that a fair thought?