Effects of Different Natural Extracts and Plant Growth Regulators on Plant Regeneration and Callus Induction from Pseudobulbs Explants through in vitro Seed Germination of Endangered Orchid Bulbophyllum auricomum Lindl.

Bulbophyllum auricomum Lindl. is a rare orchid and has flowers with an attractive fragrance. The present study investigated the tissue culture method for micropropagation. Capsules derived from artificial self-pollination were obtained for the best seed germination in MS basal medium. Plant growth regulators (1.0 mgL -1 of BAP and 2.0 mgL -1 of NAA) were affected by callus induction from subcultured pseudobulb explants. For the callus subculture, different natural plant extracts were tested in 11 treatment media. Among them, MS medium with 150 mLL -1 of coconut water was generally effective in fresh weight (1.75 0.08) and (3.01 0.20) of callus proliferation and PLBs induction at 1 and 2 months, respectively, followed by an MS combination of 30 gL -1 of banana and 20 gL -1 of potato extract. The results of a comparative study of different MS mediums containing plant growth regulators with a natural extract combination and MS medium supplemented with natural extract only showed that MS medium supplemented with a combination of natural extracts (150 mLL -1 of coconut water) and plant growth regulators (2.0 mgL -1 of BAP and 1.0 mgL -1 of NAA) obtained the highest shoot regeneration (3.37 0.17) and (6.41 0.68) after 1 month and 2 months of culturing, respectively.