Seed dormancy is due to the : -

Options

A. Ethylene
B. Abscissic acid
C. IAA
D. Starch

Answer

To solve the question regarding the cause of seed dormancy, we can follow these steps:

### Step 1: Understand Seed Dormancy
Seed dormancy is a condition in which seeds are prevented from germinating even under favorable environmental conditions. This state is crucial for ensuring that seeds do not germinate prematurely and can survive until conditions are suitable for growth.

**Hint:** Think about why seeds might need to delay germination despite favorable conditions.

### Step 2: Identify the Hormones Involved
There are several plant hormones that play roles in seed development and dormancy. The options given are:
- A) Ethylene
- B) Abscisic Acid (ABA)
- C) IAA (Indole-3-acetic acid)
- D) Starch

**Hint:** Recall the functions of these hormones in plant physiology.

### Step 3: Analyze the Role of Abscisic Acid
Abscisic acid (ABA) is known to regulate various processes in plants, particularly in response to stress. It plays a significant role in inducing and maintaining seed dormancy. ABA inhibits germination and promotes desiccation tolerance, which is vital for seeds to survive until conditions are right for germination.

**Hint:** Consider which hormone is primarily responsible for preventing germination.

### Step 4: Evaluate Other Options
- **Ethylene**: Generally promotes ripening and can sometimes promote germination.
- **IAA (Indole-3-acetic acid)**: Primarily involved in growth and development, not dormancy.
- **Starch**: A carbohydrate, not a hormone, and does not regulate dormancy.

**Hint:** Think about the specific functions of each hormone and whether they relate to dormancy.

### Step 5: Conclusion
Based on the analysis, the hormone that is primarily responsible for seed dormancy is **B) Abscisic Acid**. It prevents germination and ensures seeds remain dormant until the right conditions are present.

**Final Answer:** B) Abscisic Acid