Studies on the Utilization of Polyploidy in Tea Plant (Part 1)

We have succeeded to create new tetraploid tea plants by two methods, namely by colchicine treatment of the growing point of diploid seedlings and by sawing the seeds openly collected from triploid plants.Both induced and spontaneous tetraploid plants showed gigantic types as like as autotetraploid plants in other crops, but the leaves of the tetraploids induced from Yamatomidori variety which has small leaves were smaller than those of the tetraploid induced from Benihomare variety which has large leaves.From this result, it is thought that there must be some relations between the characters of induced tetraploid plants and those of parental diploid plants.As large leaves are not desirable in making good green tea, small leaf varieties may be suitable as a material of tea polyploidy breeding.Among the colchicine treated plants, a mixoploid plant was found. This plant had two branches, and though the leaves of each branch had almost 4n or 2n cells, the roots from these branches, on the contrary, had 2n and 4n cells respectively.This mixoploid seems to be useful for the study of development of tea plant.