(a). providing at least one protocorm or protocom-like body (PLB) of an orchid by plant tissue culture technique under sterile condition, the protocorm or PLB having a height of 2-8 mm and having an upper portion with a growing point and a lower portion without any growing point, the lower portion located beneath the upper portion;
(b). cutting the protocorm or PLB approximately at a point of half height to separate the upper portion and the lower portion such that the upper portion has a first cut surface and the lower portion has a second cut surface correspondingly;
(c). subculturing the lower portion of the protocorm or PLB in an inducing medium, and putting the second cut surface of the lower portion of the protocorm or PLB to face upward so that one or more next-generation PLBs grow from the second cut surface of the lower portion;
(d). cutting off at least one of the next-generation PLBs from the second cut surface of the lower portion when growing to a height of 2-8 mm;
(e). repeating the steps (b) through (d) one or more times if necessary;
(f). cultivating the next-generation PLBs obtained from the step (d) or (e) in a regenerating medium so as to differentiate the next-generation PLBs into plantlets; and
(g). processing a chromosome ploidy analysis to identify the ploidy level of the plantlets.