Asymbiotic seed germination and in vitro conservation of Coelogyne nervosa A. Rich. an endemic orchid to Western Ghats

Abstract

Coelogyne nervosa is an epiphytic orchid endemic to Western Ghats, South India. The mature seeds of C. nervosa were cultured on ½ MS (Murashige and Skoog), MS, Kn (Knudson) and VW (Vacin and Went) media to evaluate the seed germination response. Of the four basal media used, MS medium supported maximum seed germination. Further experiments to enhance seed germination were done on MS medium supplemented with various concentrations (10, 20, 30 and 40%) of coconut water (CW). Thirty percent CW gave the highest response in terms of percent seed germination (96), fresh weight (7.2mg/seedling) and protocorm length (15.2mm). Since CW containing medium did not support further seedling growth, each seedling was isolated and cultured on MS medium supplemented with either BA (6-benzylaminopurine) or Kin (kinetin) alone (1.0-4.0mg/l each) or in combination with NAA (1-naphthaleneacetic acid; 0.2-1.0mg/l). Maximum growth was observed on MS medium supplemented with BA (3.0mg/l) and NAA (0.5mg/l). On this medium, the seedlings reached an average length of 3.6cm with 2.8 well expanded green leaves per seedling. Similarly optimum, healthy, white root induction (3.3 roots/seedlings) was also observed on the same medium. The rooted seedlings were successfully transplanted to pots with 91% success. The 2-year-old tissue culture derived plants produced normal flowers and fruits.