Limiting Factors
The maximum rate of photosynthesis is controlled by the limiting factor.
Increasing the temperature from 10ºC to 20ºC could double the rate of photosynthesis as the plant's enzymes will be closer to their optimum working temperature.
As the temperature is increased, molecules in the cells will be moving at a faster rate due to kinetic theory.
If the temperature is raised above a certain level, the rate of photosynthesis will drop as the plant's enzymes are denatured.
They will be more likely to join onto the enzymes and react. But if this happens the plant will need more water or light so they become the limiting factor.
Most plants have ways to make up for the insufficient supply of any of them. Most plants grow towards their light source. Also a lot of plants have very deep roots that can make up for insufficient water supply. If a human wanted to increase the yield of a plant they would put up artificial lights, fertilisers to increase minerals in soil and a sprinkler system to keep the plants watered.
- Discuss the concept of the limiting factors in photosynthesis.
Temperature, concentration of CO2, availability of water, availability of minerals, intensity of sunlight, duration of sunlight, color of sunlight reaching the leaves are all factors that can limit photosynthesis. If any one of these factors is limiting, that factor will determine the rate of photosynthesis.
- Discuss the extent to which knowledge of limiting factors can be used to improve plant productivity.
Use of fertilizers and irrigation will improve yields of field crops. Removing plants that shade the field will improve yields. In a greenhouse setting, increasing CO2 concentrations will help as will the use of artificial light of high intensity and selected colors during winter months.
