Factor Affecting Photosynthesis

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Photosynthesis is the process by which plants prepare their own food while being exposed to water, chlorophyll, sunlight,  and CO₂. This process takes place primarily in the plant’s leaves. Photosynthesis is also performed by the stems of some other plants. Photosynthesis takes place in the chloroplast cells of leaves. Photosynthesis is influenced by a number of factors, including its rate and efficiency. Let’s take a look at the factors that influence photosynthesis and see how they work.

Factor Affecting Photosynthesis

Light

It is one of the most important factors influencing photosynthesis. Photosynthesis cannot occur in the dark, and the plants’ primary source of light is sunlight. Three aspects of light are critical for photosynthesis:

Intensity

Photosynthesis begins at low light intensities and gradually increases until it reaches its peak at the brightest time of day. The amount of light required by different plants varies. Photosynthesis uses up to 1.5 percent of the available light in the process, so light is generally not a limiting factor at high intensities. However, low-intensity light becomes a limiting factor because photosynthesis cannot occur without light, regardless of the amount of water or CO₂ present. When the intensity is high, the temperature of the plant rises, resulting in increased transpiration. This causes the stomata to close, resulting in less CO₂ intake. As a result, photosynthesis is reduced and, eventually, stopped. As a result, too much light inhibits photosynthesis.

Quality

Engelmann’s experiments show that chlorophyll absorbs red and blue wavelengths from the entire spectrum of light most effectively. As a result, when the plant is exposed to light of these wavelengths, photosynthesis is at its peak.

Duration

The longer the plant is exposed to light, the longer the photosynthesis process will last. Photosynthesis will occur as long as the plant’s temperature remains balanced.

Carbon Dioxide Concentration

Among other gases, the atmosphere contains 0.3 percent of carbon dioxide. Plants absorb carbon dioxide from the atmosphere. However, because the amount of CO₂ .The air is so small, it acts as a limiting factor for photosynthesis. Experiments have been carried out to investigate the rate of photosynthesis as the concentration of CO₂ in the atmosphere increases.

When light and temperature are not the limiting factors, increasing CO₂ concentration leads to an increase in photosynthesis rate. However, after a certain point, CO₂ begins to accumulate in the plant, slowing down the process. As a result, excess CO₂ inhibits photosynthesis, especially when it begins to accumulate.

Temperature

It is common for all biological and biochemical processes to occur best in a specific temperature range. This is true for photosynthesis. When CO₂ and light are not limiting factors, the rate of photosynthesis increases with increasing temperature until it reaches the optimum level for that plant. When the levels on both sides of the normal range exceed the optimum, the enzymes are deactivated or destroyed, and photosynthesis ceases.

Water

Water is thought to be one of the most important factors influencing photosynthesis. When there is a decrease in water intake or availability, the stomata begin to close to prevent any water loss during transpiration. With the stomata closing, CO₂ intake ceases, affecting photosynthesis. As a result, the effect of water on photosynthesis is indirect rather than direct.

Oxygen

Photosynthesis benefits from optimal oxygen levels. In C₃ plants, oxygen is required for photorespiration, and the product of photorespiration  is CO₂ , which is required for photosynthesis. Additionally, the energy generated during oxygen respiration is required for photosynthesis. An increase in oxygen levels above the optimum for the plant, on the other hand, inhibits photosynthesis.

This is due to the fact that oxygen tends to degrade the intermediaries formed during photosynthesis. Oxygen also combines with CO₂ to form RUBISCO, which is a component of the dark reaction of photosynthesis and photorespiration. As a result of increased O₂ levels, RUBISCO will combine with O₂ to initiate photorespiration and photosynthesis will slow down.

Blackman’s Principle of Limiting Factors

When a process is governed by more than one factor, the rate of the process is governed by the factor that is closest to its minimum value, according to this principle.

For example, if a leaf is exposed to a certain amount of light intensity at a constant temperature but has less CO₂ available, the rate of photosynthesis will not increase as the light intensity increases. As a result, CO₂ is the limiting factor in this case.

Important Internal Factors Regulating the Rate of Photosynthesis

Protoplasmic Factors

There is an unknown factor in protoplasm that influences photosynthesis rate. This factor has an impact on the dark reactions. The decrease in photosynthesis rate at temperatures above 30°C or at high light intensities in many plants suggests that this unknown factor is an enzyme.

Chlorophyll Content

Chlorophyll is a critical internal factor in photosynthesis. The amount of CO₂ Fixed by one gram of chlorophyll in one hour is referred to as the photosynthetic number or assimilation number. It is usually constant for a plant species, but it varies on occasion. The assimilation number of a species’ variegated variety was discovered to be greater than the variety with green leaves.

Accumulation of End Products

The accumulation of food in the chloroplasts slows photosynthesis.

Structure of Leaves

The amount of CO₂ that reaches the chloroplasts is determined by structural features of the leaves such as stomatal size, position, and behaviour, as well as the number of intercellular spaces. Other characteristics, such as cuticle thickness, epidermis, the presence of epidermal hairs, the amount of mesophyll tissue, and so on, influence the intensity and quality of light reaching to the chloroplast.

CO₂ Compensation Point

It is the value or point in light intensity and atmospheric CO₂ concentration at which the rate of photosynthesis is just equal to the rate of respiration in photosynthetic organs, resulting in no net gaseous exchange. The light compensation point for shade plants is 2.5-100 ft. candles and 100-400 ft. candles for sun plants. The CO₂ compensation point in CO₂ plants is very low (0-5 ppm), whereas it is quite high in C₃ plants (25-100 ppm). A plant cannot survive for long at the compensation point because there is a net loss of organic matter due to non-green organ respiration and dark respiration.

Conclusion

Photosynthesis is the process by which plants prepare their own food while being exposed to water, chlorophyll, sunlight, and CO₂. This process takes place primarily in the plant’s leaves. It is one of the most important factors influencing photosynthesis. Photosynthesis begins at low light intensities and gradually increases until it reaches its peak at the brightest time of day. Engelmann’s experiments show that chlorophyll absorbs red and blue wavelengths from the entire spectrum of light most effectively. Among other gases, the atmosphere contains 0.3 percent of carbon dioxide. Plants absorb carbon dioxide from the atmosphere. It is common for all biological and biochemical processes to occur best in a specific temperature range. Water is thought to be one of the most important factors influencing photosynthesis. When there is a decrease in water intake or availability, the stomata begin to close to prevent any water loss during transpiration. Photosynthesis benefits from optimal oxygen levels. There is an unknown factor in protoplasm that influences photosynthesis rate. Chlorophyll is a critical internal factor in photosynthesis. The amount of CO₂ that reaches the chloroplasts is determined by structural features of the leaves such as stomatal size, position, and behaviour, as well as the number of intercellular spaces. It is the value or point in light intensity and atmospheric CO₂ concentration at which the rate of photosynthesis is just equal to the rate of respiration in photosynthetic organs, resulting in no net gaseous exchange.