The various methods of vegetative propagation are:
(iv) tissue culture.
Layering: In layering, roots are induced on the stem of a rooted plant. When roots develop, that part of stem is detached from the parent plant and grown in the soil. Layering is of two types:
(i) Mound layering: A lower branch of a rooted plant is bent and buried in the moist soil. The tip of the branch should remain above the ground. In a few days, the buried part of the blanch develops roots. It is now cut of from the parent plant and grown in the soil as a new plant. This method is used in the propagation of grapevine, strawberry, raspberry, jasmine, etc.
(ii) Air layering: This method is used in plants like crotons whose branches cannot be bent anti buried in the soil. The stem is girdled, i.e., a ring of bark is removed and then it is covered with a moist moss or cotton and enclosed in a polythene bag. After a few days, roots emerge from this region and branch is cut off from the parent plant. It can now be planted in the soil as a new plant. This method is used in loose, rubber plant, guavas, pear, apple, mangoes, etc.