Inhibition of Dendrobium bicaudatum Reinw. ex Lindl growth using Paclobutrazol for in vitro conservation

D. bicaudatum orchid has become threatened with extinction. Environmental damage due to human activities and overcollection of orchids has triggered the extinction of orchids in their natural habitat. In situ and ex situ conservation measures need to be taken to reduce the threat of extinction for orchids. This research aims to investigate the effect of paclobutrazol (PBZ) on culture mediums as a plant growth inhibitor, one of which is in vitro conservation measures, and was conducted experimentally using a completely randomized design. The independent variables were the concentrations of PBZ of 0, 1, 3, and 5 mg L-1, respectively, which were added to the growing medium in the form of solid MS medium. The medium-term conservation of D.bicaudatum orchids with the addition of paclobutrazol exhibited a very significant result. Inhibition of vegetative growth such as the number of leaves and root length was exhibited by 1-5 mg L-1 PBZ, while the stem diameter, as one of the dependent variables, increased more in all treatment groups than in the control group. Reduced number of roots occurred in the groups of treatments of 1 mg L-1 PBZ and 3 mg L-1 PBZ. Keywords: extinction, in Vitro culture, reductionKeberadaan anggrek D. bicaudatum mulai mengkhawatirkan. Kerusakan alam akibat aktivitas manusia dan pengambilan anggrek di alam secara berlebih memicu kepunahan anggrek pada habitat asal. Tindakan konservasi tanaman baik secara in situ maupun ex situ perlu dilakukan untuk mengurangi ancaman kepunahan anggrek tersebut. Penelitin bertujuan untuk menyelidiki efek dari paclobutrazol pada media kultur sebagai penghambat pertumbuhan tanaman, salah satu upaya konservasi secara in vitro. Penelitian dilakukan secara eksperimental menggunakan rancangan acak lengkap. Variabel bebas penelitian adalah konsentrasi PBZ berturut-turut 0, 1, 3, dan 5 mg L-1 yang ditambahkan pada medium tanam berupa MS padat. Hasil penelitian menunjukkan konservasi jangka menengah anggrek D. bicaudatum dengan penambahan pactobutrazol menunjukkan pengaruh yang sangat nyata. Penghambatan pertumbuhan vegetatif seperti jumlah daun dan panjang akar terdapat pada PBZ 1-5 mg L-1, sedangkan pada variabel diameter batang terjadi pembesaran pada semua perlakuan dibandingkan kontrol. Reduksi jumlah akar terjadi pada perlakuan PBZ 1 dan 3 mg L-1. Kata kunci: kepunahan, kultur in Vitro, reduks