The limiting factors are the rare factors. These are environmental or resource conditions that limit the growth or spread of an ecosystem. These can be physical or biological factors characterized by increased population distribution or increase or decrease.
Blackman’s Law of Limiting Factors
- A plant chemist, Blackman investigated the limiting factors in photosynthesis in plants. He noted that biological factors are affected by a number of factors, but the magnitude of their effect on overall performance varies. Let’s take the example of photosynthesis. Plants need sufficient water, sunlight, chloroplasts, heat, carbon dioxide and chlorophyll for photosynthesis. Deficiencies in any of these components will affect photosynthesis.
- Any physical process affected by more than one factor is governed by the law of finite factors.
- The relative size of the dot is more important than the absolute size.
- The fact that it exists in small quantities is the limiting factor.
- When the rate of the process is constant for a limiting factor, only the amount of the limiting factor can be controlled, for example, a leaf that can consume 5mg of CO2 per hour in photosynthesis receives a certain amount of light intensity. If only 1mg of CO2 enters the leaf in an hour, the rate of photosynthesis is limited by the CO2 factor. As the concentration of CO2 increases, so does the rate of photosynthesis. A further increase in
- CO2 concentration will not affect the rate of photosynthesis. It increases if light intensity increases.
Criticism of Law of Limiting Factors
Explaining the concept of limiting point, Blackman showed a sudden stop in the rate of photosynthesis caused by low light intensity. According to collaborators, the rate of photosynthesis does not decrease rapidly, but gradually with each limiting factor.
This is because not all chloroplasts live in the same environment. The visible ones are more exposed to light and CO2 than the heavier ones. If these factors are limiting, then photosynthesis will be affected only in some chloroplasts. As a result, the rate of photosynthesis gradually decreases.