Question

what is stock and scion?

Answer 1

During vegetative propagation ,i.e, stem cutting the plant part which has root system and fixed as it is called stock.

The shoot system of another plant which is tied with stock is called scion.

Answer 2

two plants are joined together in drafting method at that time one which is attached to soil is called stock or root stock and the cut stem of other plant without roots is called scion or graft.
hope it helps you.