Question

Crabgrass is a C4 plant why does it tend to predominant on the lawn during a hot season?

Answer 1

As it is stated that the crabgrass predominant in the hot season, it happens because of following advantages of being a C4 plant:

-The optimum temperature for photosynthesis is high in C4 plants.

- They like very sunny areas with warm temperatures. They can withstand cool evening temperature.

- They can keep their stomata closed more than C3 plants because they are more efficient in incorporating CO2. This minimize their water loss.

- C4 plants can perform photosynthesis even in the closed conditions of stomata but C3 plants cannot.

- C4 plants have evolved in a high CO2 environment. This increase both their nitrogen and water use efficiency compared to C3 plants.

-C4 plants avoid Photo respiration. ( photo respiration is a wasteful reaction that occurs when plants take in oxygen and give out CO2 instead of taking in CO2 and releasing oxygen.)

-C4 plants make a four carbon sugar during Calvin cycle instead of 2 three carbon sugars as in C3 plants. This larger sugar in C4 plants bring more CO2 to RuBisCO enzyme, reducing oxygen levels and making the process energy intensive. More CO2 is brought into the process because of how cells are located.

-C4 plants have greater rates of CO2 assimilation than C3 plants.