Effects of plant growth regulators on germination and growth of Terrestrial Orchid, Habenaria rhodocheila Hance

Abstract

Habenaria rhodocheila is the one of endanger orchid species, thus, improvement of seed germination rate and growth of H. rhodocheila are needed. This study was conducted to investigate the effects of plant growth regulators on the seed germination and the growth of H. rhodocheila. Pods of H. rhodocheila were harvested and dried for two weeks. Then, the pods were opened and seeds were collected. The seeds were divided for three treatments. First, seeds were pre-treatment with plant growth regulators before sowing on the Malmgren modified terrestrial orchid medium (MM). Second, seeds were sown on Murashige and Skoog medium (MS) containing plant growth regulator at different concentration, Third, the seeds were sown on MM medium supplemented with various plant growth retardants. The results showed that the highest seed germination rates of H. rhodocheila occurred under the treatments of pre-treatment with 0.1 ppm of NAA, 1.0 ppm of BAP or 10 ppm and 1000 ppm of ethephon while plant growth retardants had no effect on seed germination. After seeds developed to protocorms, the protocorms were cultured on media supplemented with the NAA + BAP, NAA + TDZ and BAP + sucrose at different concentrations. The results showed that 0.5 ppm NAA + 2.0 ppm BAP was recommended for callus induction and MS medium supplemented with 0.5 ppm BAP + 50 g L-1 sucrose was recommended for root formation.