Option 1: Polyploid breeding refers to the process of artificially increasing the number of sets of chromosomes in a plant. This technique does not rely on the concept of cellular totipotency as it is not concerned with regenerating whole plants from individual cells.

Option 2: Tissue culture is the correct answer. It is a plant propagation technique that involves growing plant cells, tissues, or organs in a controlled environment outside of the plant body. Cellular totipotency, the ability of a single cell to regenerate into an entire plant, is the basis of tissue culture. Through the manipulation of plant cells, tissues, or organs in the lab, new plants can be produced. This technique is widely used in crop improvement to generate large numbers of identical plants rapidly.

Option 3: Induced mutations involve the deliberate induction of mutations in plants to create genetic variations. While this technique is useful for crop improvement, it does not directly rely on the concept of cellular totipotency.

Option 4: Hybridization involves the crossing of two genetically different plants to produce offspring with desirable traits. Although hybridization is an important technique in crop improvement, it does not rely on the concept of cellular totipotency.

Therefore, the correct answer is Option 2: