Only macronutrients were added in which nutrient solution?

Options

A. Amon's
B. Knop's
C. Hoagland's
D. All of these

Answer

To answer the question "Only macronutrients were added in which nutrient solution?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand Macronutrients**: Begin by identifying what macronutrients are. Macronutrients are essential elements required by plants in larger quantities. There are nine macronutrients: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), and Sulfur (S).

2. **Identify Nutrient Solutions**: Recognize that there are various nutrient solutions used in plant nutrition studies. Notable examples include the solutions developed by researchers like Knop, Hoagland, and Arnon.

3. **Review Solutions**:
- **Knop's Solution**: This solution contains macronutrients such as Calcium Nitrate and Potassium Nitrate, which are rich in macronutrients.
- **Hoagland's Solution**: This solution is also known for containing a variety of macronutrients necessary for plant growth.
- **Ammons Solution**: Similar to Hoagland's, this solution is designed to provide essential macronutrients.

4. **Conclusion**: Since all three solutions (Knop, Hoagland, and Ammons) are formulated to include only macronutrients, the answer to the question is that these solutions contain macronutrients.

5. **Final Answer**: Therefore, the correct response to the question is that the nutrient solutions developed by Knop, Hoagland, and Ammons all contain only macronutrients.