Magnitude of primary productivity is affected by

Options

A. Temperature , Availability of nutrients
B. Solar radiations available, Availability of nutrients
C. Photosynthetic capacity of producers
D. All of these

Answer

To answer the question regarding the factors affecting the magnitude of primary productivity, we can follow these steps:

### Step-by-Step Solution:

1. **Define Primary Productivity**:
- Primary productivity refers to the rate at which organic compounds are created by producers (like plants) through the process of photosynthesis. It is a measure of how much energy is captured by photosynthetic organisms in a given area over a specific time period.

2. **Identify Factors Affecting Primary Productivity**:
- Several factors can influence the magnitude of primary productivity:
- **Temperature**: The rate of photosynthesis can be affected by temperature, as different species have optimal temperature ranges for growth.
- **Nutrient Availability**: Nutrients such as nitrogen, phosphorus, and potassium are essential for plant growth and can limit productivity if they are in short supply.
- **Solar Radiation**: The amount of sunlight available directly impacts the photosynthetic rate, as sunlight is a key component of photosynthesis.
- **Photosynthetic Capacity of Producers**: Different plant species have varying efficiencies in converting sunlight into chemical energy, which affects overall productivity.

3. **Evaluate the Options**:
- The question provides four options:
1. Temperature and nutrient availability
2. Solar radiation available and availability of the nutrients
3. Photosynthetic capacity of the producers
4. All of these
- Since all the mentioned factors (temperature, nutrient availability, solar radiation, and photosynthetic capacity) can affect primary productivity, the most comprehensive answer would be option 4: "All of these".

4. **Conclusion**:
- Therefore, the magnitude of primary productivity is affected by multiple factors, including temperature, nutrient availability, solar radiation, and the photosynthetic capacity of the producers.

### Final Answer:
The magnitude of primary productivity is affected by all of these factors: temperature, nutrient availability, solar radiation, and the photosynthetic capacity of the producers.