Haines et al. - Propagating two kumarahou species

New Zealand Journal of Botany abstracts

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

Leslie Haines

I. L. Ennis

D. J. Blanchon

School of Natural Sciences
Unitec New Zealand
Private Bag 92 025
Auckland 1025, New Zealand

C. M. Triggs

Department of Statistics
The University of Auckland
Private Bag 92 019
Auckland 1142, New Zealand

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.

Keywords Pomaderris hamiltonii; Pomaderris kumeraho; pale-flowered kumarahou; Rhamnaceae; dormancy; germination; scarification; sulphuric acid; smoke; heat; boiling water

B06016; Online publication date 27 February 2007; Received 11 May 2006; accepted 19 December 2006

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