Most deleterious effect of aluminium toxicity to plant is:

Options

A. Necrosis at high concentration
B. Impaired phosphate availability
C. Weedicide effect
D. Disruption of iron uptake

Answer

### Step-by-Step Solution:

1. **Understanding Aluminium Toxicity**:
- Aluminium toxicity occurs when there is an excessive amount of aluminium in the soil, which can be absorbed by plants. This can lead to various harmful effects on plant health.

2. **Identifying the Effects**:
- The question asks for the most deleterious (harmful) effect of aluminium toxicity on plants. We need to evaluate the options provided.

3. **Evaluating Each Option**:
- **Option 1: Necrosis at high concentration**:
- Necrosis refers to the death of cells or tissues. While it can occur in plants, it is not specifically caused by aluminium toxicity. Therefore, this option is incorrect.

- **Option 2: Impaired Phosphate Availability**:
- This option suggests that aluminium toxicity would lead to phosphate deficiency. However, aluminium does not directly cause phosphate deficiency, making this option incorrect as well.

- **Option 3: Weedy Side Effect**:
- This option implies that aluminium toxicity would have a weedy side effect, which means it would kill the plants. However, aluminium toxicity does not function like herbicides that kill weeds. Thus, this option is also incorrect.

- **Option 4: Disruption of Iron Uptake**:
- This option states that aluminium toxicity disrupts iron uptake in plants. Studies have shown that high levels of aluminium can hinder the synthesis of ferritin (a protein that stores iron) and inhibit iron uptake. This can lead to oxidative damage in plants due to insufficient iron availability. Therefore, this option is correct.

4. **Conclusion**:
- The most deleterious effect of aluminium toxicity in plants is the **disruption of iron uptake**.

### Final Answer:
The most deleterious effect of aluminium toxicity to plants is **disruption of iron uptake**.

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