Find out the correct reason for non-existence of sharp annual rings in Secondary dicot root as found in secondary wood of dicot stem.

Options

A. Lack of periclinal divisions in vascular cambium
B. Production of more secondary xylem to inside and less secondary phloem outside
C. Relatively less difference in the climate of the soil during different seasons.
D. Unexposure of root to proper wet conditions.

Answer

To find the correct reason for the non-existence of sharp annual rings in the secondary dicot root, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Annual Rings**:
- Annual rings are formed in the secondary wood of dicot stems due to the activity of the vascular cambium, which produces new xylem and phloem each year. The growth varies with the seasons, leading to distinct layers of wood (spring wood and autumn wood).

2. **Secondary Growth in Dicot Stems**:
- In dicot stems, the cambium is located between the xylem and phloem and can form a complete ring. This allows for the differentiation of wood based on seasonal changes, resulting in sharp annual rings.

3. **Secondary Growth in Dicot Roots**:
- In contrast, the secondary growth in dicot roots does not exhibit the same pattern. The cambium in roots does not form a complete ring like in stems. This is primarily because the environmental conditions affecting root growth are different from those affecting stem growth.

4. **Environmental Influence**:
- The roots are typically underground, where they are less influenced by seasonal changes compared to the above-ground parts of the plant. The soil environment remains relatively stable throughout the year, lacking the sharp seasonal variations that lead to the formation of distinct annual rings.

5. **Conclusion**:
- Therefore, the main reason for the absence of sharp annual rings in secondary dicot roots is the relatively less difference in the climate of the soil during different seasons compared to the above-ground environment. This leads to a lack of distinct growth patterns in the roots.

### Final Answer:
The correct reason for the non-existence of sharp annual rings in secondary dicot roots is: **"Relatively less difference in the climate of the soil during different seasons."**

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