Give three criteria of essentiality of an element.

Explanation

To determine whether an element is essential for plant growth and development, three primary criteria of essentiality can be established. Here’s a step-by-step breakdown of these criteria:

### Step-by-Step Solution:

1. **Absolute Essentiality for Growth and Reproduction**:
- The first criterion is that the element must be absolutely essential for supporting normal growth and reproduction of the plant. This means that if the element is not present, the plant will not be able to grow or reproduce effectively. For instance, without certain nutrients, plants may fail to produce flowers or fruits.

2. **Deficiency Symptoms**:
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