In vitro seed germination and seedling growth of the orchid Dendrobium primulinum Lindl.

Abstract

Dendrobium primulinum Lindl. (D. Primulinum L.) is one of the important epiphytic orchid species for horticultural and commercial use. It is listed as a rare and critically endangered species of orchid. The present study is intended to conserve the orchid species through the micropropagation technique. The in vitro seed germination and seedling growth was carried out by taking a mature pod of D. Primulinum L. in Murashige and Skoog (MS) media, and the MS media supplemented with a varied concentration (0.5, 1.0, 1.5 and 2 mg/L) of 6-benzylaminopurine (BAP), and a fixed concentration (0.5 mg/L) of α-naphthalene acetic acid (NAA). Sequential phases of seed germination, protocorm formation, and seedling development in the presence of growth regulators were determined in the study. The significance of hormonal effects was determined by using One-Way Analysis of Variance (ANOVA, p≤0.05). The seed germination started after two weeks of culture in the media supplemented with BAP. The maximum seedling growth was obtained in the media supplemented with 1.5 mg/L of BAP. Although the hormone-free basal medium revealed an ideal condition for seed germination and spherules formation, the presence of an appropriate concentration of growth regulators such as 0.5 mg/L NAA or a combined  0.5 mg/L BAP + 0.5 mg/L NAA expressed a synergistic effect to enhance the protocorm formation and seedling development.   Key words: In vitro, Dendrobium primulinum, 6-benzylaminopurine (BAP), α-Naphthalene acetic acid (NAA).