________________is always the main objective of plant breeding.

Answer

**Step-by-Step Solution:**

1. **Understanding Plant Breeding:**
- Plant breeding is defined as the purposeful manipulation of plant species to create desired plant types.

2. **Purpose of Manipulation:**
- The manipulation is done to develop plants that are better suited for cultivation, which includes improving their characteristics.

3. **Desired Outcomes:**
- The desired outcomes of plant breeding include creating plants that have higher yields, are disease-resistant, and can tolerate environmental stresses such as salinity, extreme temperatures, and drought.

4. **Identifying the Main Objective:**
- Among all the benefits and improvements that can be achieved through plant breeding, the primary goal is to increase the yield of the plants.

5. **Conclusion:**
- Therefore, the blank in the question can be filled with "Higher yield," indicating that higher yield is always the main objective of plant breeding.

**Final Answer:**
"Higher yield is always the main objective of plant breeding."

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