Carbon dioxides fertilisation effect is

Options

A. Warming effect of `CO_(2)`
B. Photosynthetic enhancement of elevated `CO_(2)` level
C. Both summer and temperature rainfall at higher latitudes
D. Poleward shifting of temprature zone .

Answer

**Step-by-Step Solution:**

1. **Understanding Carbon Dioxide Fertilization Effect**: The carbon dioxide fertilization effect refers to the enhancement of plant photosynthesis due to increased levels of carbon dioxide (CO2) in the atmosphere. This phenomenon is particularly significant in C3 plants, which are a type of plant that utilizes the C3 carbon fixation pathway.

2. **Role of Elevated CO2 Levels**: When the concentration of CO2 in the atmosphere increases, it can lead to a rise in the rate of photosynthesis in plants, provided that other conditions such as temperature, water availability, and light intensity are also favorable.

3. **Impact on Stomatal Conductance**: As CO2 levels rise, plants may partially close their stomata (the small openings on leaves that allow gas exchange). This partial closure reduces water loss through transpiration, which is the process of water vapor exiting the plant.

4. **Conclusion of the Effect**: The overall response of plants to elevated CO2 levels, which includes increased photosynthesis and decreased transpiration, is what defines the carbon dioxide fertilization effect. This effect indicates that higher CO2 levels can enhance plant growth and productivity.

5. **Identifying the Correct Option**: From the options provided, the correct answer is the second option: "photosynthetic enhancement of elevated carbon dioxide level." The other options do not accurately describe the carbon dioxide fertilization effect.

**Final Answer**: The carbon dioxide fertilization effect is the photosynthetic enhancement of elevated carbon dioxide levels.

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