DOSIS LETAL LD20 DAN LD50 SERTA EFEK IRADIASI SINAR GAMMA PADA PROTOKORM Dendrobium discolor Lindl.

Gamma ray irradiation is one of plant breeding methods for increasing genetic diversity. In previous irradiation research of Dendrobium discolor Lindl. has not determined a dosage of LD20-50 yet, which generated the highest mutant variations. Thus, further research was carried out by increasing irradiation dosage. Research aimed were to determine the effect of irradiation on Dendrobium discolor Lindl. protocorms using lethal doses LD20 and LD 50, and to obtain new potential mutant with specific morphological characters and better plant performance. The dosages of Gamma ray irradiation used 0, 15, 30 and 60 Gray (Gy). A Completely Randomized Design (CRD) with six replicates was applied. The results showed that LD20 and LD50 values were 22,16 and 58,8 Gy. Gamma ray irradiation treatments of 15 Gy and 30 Gy dosages exhibited morphological changes in leaf shapes and more rosette in leaf arrangement. Consequently, these dosages ranged are recommended, particularly for this orchid species. Treatment of 60 Gy dosage caused entire explants died after 13 months irradiation, subsequent to the third subculture (MIV3).