All given factors promote absorption of water by roots , except

Options

A. well - aerated soil
B. highly concentrated soil solution
C. optimum soil temperature
D. available soil water

Answer

To solve the question, "All given factors promote absorption of water by roots, except," we will analyze each option provided to determine which factor does not promote water absorption by roots.

### Step-by-Step Solution:

1. **Identify the Options**: We need to evaluate the given options to see which one does not promote water absorption by roots.

2. **Evaluate Well-Aerated Soil**:
- Well-aerated soil is crucial for root respiration. Roots need oxygen to carry out cellular respiration, which is essential for energy production and overall plant health.
- **Conclusion**: Well-aerated soil promotes water absorption.

3. **Evaluate Highly Concentrated Soil Solution**:
- A highly concentrated soil solution contains high levels of salts (e.g., Na2SO4, MgCl2, KCl). This increases the salinity of the soil.
- High salinity can create osmotic stress on plants, making it difficult for roots to absorb water.
- **Conclusion**: Highly concentrated soil solution does not promote water absorption.

4. **Evaluate Optimum Soil Temperature**:
- Optimum soil temperature is important for the activity of soil organisms and root function. It supports metabolic processes that are vital for plant growth.
- **Conclusion**: Optimum soil temperature promotes water absorption.

5. **Evaluate Availability of Soil Water**:
- The availability of soil water is directly related to the ability of roots to absorb water. More water in the soil means more water can be absorbed by the roots.
- **Conclusion**: Availability of soil water promotes water absorption.

6. **Final Conclusion**:
- Based on the evaluations, the factor that does not promote water absorption by roots is **highly concentrated soil solution**.

### Answer:
The correct option is **highly concentrated soil solution**.

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