Effects of pH and sucrose on seed germination of Paphiopedilum exul (Ridl.) Rolfe

Abstract

© 2017, International Society for Horticultural Science. All rights reserved. Paphiopedilum exul (Ridl.) Rolfe is one of terrestrial or lithophytic orchids also known as the ‘‘lady’s slipper orchid’’. The distribution is native around limestone mountain at western and eastern coasts of Thailand. The suitable conditions for P. exul seed germination were constructed. Seeds from 5-month-old fruits cultured on half-strength Murashige and Skoog agar medium (½ MS) at different pH levels (5, 5.6, 6.2, and 6.8) and supplemented with 10, 20, and 30 g L-1sucrose. Seeds were cultured in dark conditions for 2 months and then cultured at 25±3°C under light intensity of 37 µmol m-1s-1for 16 h d-1for 1 month. The results showed that different pH levels affected seed development to germination. The pH 5, 5.6, 6.2, and 6.8 gave seed germination of 28.07, 26.33, 21.75 and 19.12%, respectively. Sucrose concentrations did not affect seed germination significantly, but 20 g L-1sucrose tended to give high seed germination at 24.97%. There is no interaction between sucrose and pH on seed germination.