At a temperature above `35^(@)C`

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the effects of temperature above 35°C on the rates of photosynthesis and respiration in plants.

2. **Identify the Optimum Temperature for Photosynthesis**: The optimum temperature for photosynthesis is typically between 25°C to 35°C. At this range, the rate of photosynthesis is maximized due to optimal enzyme activity.

3. **Effects of Temperature Above 35°C**: When the temperature exceeds 35°C, the rate of photosynthesis begins to decline. This decline occurs because high temperatures can denature enzymes involved in photosynthesis, particularly those responsible for carbon fixation.

4. **Enzymes Affected**: The key enzyme affected by high temperatures is Rubisco (Ribulose bisphosphate carboxylase/oxygenase), which is crucial for the carboxylation process in photosynthesis.

5. **Comparison with Respiration**: While the rate of photosynthesis declines at higher temperatures, the rate of respiration does not decline as quickly. Respiration can continue at higher temperatures, albeit at a reduced efficiency.

6. **Conclusion**: Therefore, at temperatures above 35°C, the rate of photosynthesis declines earlier than the rate of respiration.

### Final Answer:
At temperatures above 35°C, the rate of photosynthesis will decline earlier than that of respiration.