Propagating the pale-flowered kumarahou (Pomaderris hamiltonii) and kumarahou (Pomaderris kumeraho) from seeds

Abstract

The germination rate in the nursery of Pomaderris hamiltonii and P. kumeraho has been observed to be low. Poor germination for a number of species can be due to a range of seed dormancy mechanisms. Five different dormancy-breaking treatments were trialled. Scarification using boiling water and sulphuric acid significantly improved germination in both species (for P. hamiltonii the germination percentages were 9.3 for the control, 14 for boiling water, and 32.6 for acid; for P. kumeraho the germination percentages were 3.4 for the control, 27.3 for boiling water, and 59.3 for acid), by breaking the impervious coat. The most successful treatments achieved 97% germination (acid plus warmth during germination) for P. kumeraho and 50% germination (boiling water plus warmth during germination) for P. hamiltonii. Smoke exposure followed by pre-sowing heat significantly (P < 0.011) improved germination for P. hamiltonii, but not for P. kumeraho, suggesting different dormancy-breaking stimuli. The response of both species to treatments which break physical dormancy may indicate an ecological role for high heat events such as fire. Embryo viability for both species is high (94%) while germination percentages were low (5.9% and 10.3%, respectively). It is possible there are other barriers to germination. © 2007 Taylor & Francis Group, LLC.