Question

the modified root used for vegetative propagation is

Answer 1

Vegetative Propagation by Roots. In this process, new plants grow out of the modified roots called tubers. Some plant roots also develop adventitious buds. These buds grow and form new plants/sprouts under the right conditions.

Answer 2

Here in which swollen roots are buried inside soil to obtain new plants.

Example :

Dahilia, sweet potato ,etc