It has been demonstrated that a variety of plant species can be conveniently propagated through the techniques of cell, tissue or organ culture. This is popularly described as clonal propagation ormicropropagation.
The major benefits of this method include the following; (i) rapid multiplication of superior clones and maintenance of uniformity; (ii) multiplication of disease free plants and (iii) multiplication of sexually derived sterile hybrids. In most cases, clonal propagation is achieved by placing . sterilized shoot tips or auxiliary buds onto a culture medium “that is sufficient to induce formation of multiple buds. This method has already been used to propagate a large number of marketable ornamentals.
Following stages are involved in the method of clonal propagation: (i) Stage I involves establishment of tissue in vitro, (ii) Stage II involves multiplication of shoots (often media are not changed between stage I and stage II). (iii) Stage III concerns root formation and conditioning of propagules prior to transfer to the green house; this stage requires alteration of media for promotion of root formation, (iv) Stage IV involves growth in pots followed by field trials. The number of steps in micropropagation may sometimes be reduced to three or two as shown in diagram.
A wide range of plants have now been regenerated through technique of tissue culture. This has been found particularly useful for propagation of tree species, so that a large number of plant species have been successfully grown by tissue culture.