The technique used for studying the effects of deficiency or toxicity of mineral nutrients on plant growth and metabolism is called -

Options

A. Hydrosonics
B. Hydrosphere
C. Solution culture
D. Hygroponics

Answer

To answer the question regarding the technique used for studying the effects of deficiency or toxicity of mineral nutrients on plant growth and metabolism, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a specific technique that allows researchers to study how mineral nutrient deficiencies or toxicities impact plant growth and metabolism.

2. **Identifying Relevant Techniques**: There are several techniques used in plant nutrition studies, including:
- Hydroponics
- Solution culture
- Hygrospare
- Other methods

3. **Evaluating Techniques**:
- **Hydroponics**: This is a method of growing plants without soil, using mineral nutrient solutions in a water solvent. It allows precise control over nutrient availability and can easily induce deficiency or toxicity by altering nutrient concentrations.
- **Solution Culture**: Similar to hydroponics, this involves growing plants in a nutrient solution but may not always provide the same level of control as hydroponics.
- **Hygrospare**: This method is not commonly recognized in the context of studying mineral nutrition in plants.

4. **Conclusion**: Among the techniques listed, hydroponics is the most suitable method for studying the effects of mineral nutrient deficiencies and toxicities on plant growth and metabolism. It allows for controlled experiments where specific nutrients can be manipulated.

5. **Final Answer**: The correct answer is **Hydroponics**.