Factors affecting in vitro seed germination and shoot proliferation of galax [Galax urceolata (Poir.) Brummitt].

To overcome the limitations of traditional propagation of Galax (Galax urceolata (Poir.) Brummitt), the feasibility of in vitro propagation was explored. We studied the effects of cold stratification, seed maturity, light intensity, pH and plant growth regulators on in vitro seed germination and subsequent shoot proliferation of Galax. Our results demonstrated that cold stratification enhanced seed germination. Seeds cold stratified at 5 degrees C for a month resulted in significantly higher seed germination than seeds treated at 22 degrees C for the same period. The level of seed maturity had an impact on seed germination. More mature dark brown seeds consistently produced higher seed germination (> 70%) than less mature light orange seeds (between 30% and 40%). The highest germination percentage of 76% was obtained with dark brown seeds stratified at 5 degrees C. Light exposures stimulated germination. Light exposure at 97 umol m-2s-1 and minimal light at 17umol m-2s-1 promoted significantly higher seed germination percentages (64% and 56% respectively) than total dark (18%). Germination media at pH levels of 4.2, 5.0 or 5.8 had no effect on germination, irrespective of seed maturity. Gibberellic acid (GA3) negatively affected germination, which was significantly reduced germination from 49% to around 30%. Additions of 6-benzylaminopurine (BAP) and indole-3-butyric acid (IBA) at different ratios in the growing medium significantly influenced shoot proliferation. The ratio of 1:1 of BAP : IBA produced the highest shoot number (8.1). All other ratios, (3:1, 6:1 and 9:1) showed no promotive effect on shoot proliferation. Abnormal shoots and shoot hyperhydricity were also observed in cultures with 6:1 and 9:1 of BAP and IBA ratios. This is the first report on successful in vitro propagation of galax.