Floral biology and breeding system of pohutukawa (Metrosideros excelsa, Myrtaceae)

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dc.contributor.author Schmidt-Adam, G. en
dc.contributor.author Gould, K.S. en
dc.contributor.author Murray, B.G. en
dc.date.accessioned 2009-08-24T06:51:30Z en
dc.date.available 2009-08-24T06:51:30Z en
dc.date.issued 1999 en
dc.identifier.citation New Zealand Journal of Botany 37 (4), 687-702. 1999 en
dc.identifier.issn 0028825X en
dc.identifier.other eid=2-s2.0-0033379735 en
dc.identifier.uri http://hdl.handle.net/2292/4782 en
dc.description An open access copy of this article is available from the publishers website. en
dc.description.abstract The floral biology and breeding system of pohutukawa (Metrosideros excelsa, Myrtaceae), a mass-flowering tree of northern New Zealand coastlines, were examined. Trees flower over a peak period of 2 weeks, and compound inflorescences contain an average of 14.3 showy, hermaphrodite, red brush flowers that remain open for 7 days. A brief female flower stage (mean duration 1.3 d) is followed by the main hermaphrodite phase that lasts for 4 days. Neither dichogamy nor herkogamy is important in preventing pollen and stigma interference. Pollen is highly viable (93.6%), and stigma receptivity extends for at least 9 days, as indicated by peroxidase activity, pollen germination, pollen tube length 24 h after pollination, and seed set. Stigmatic exudate production appears to increase up to 5 days post-anthesis. On average, flowers produce 46 ?l nectar per day, containing 18% (w/v) sucrose. Floral design and display of pohutukawa are consistent with high levels of autogamous and geitonogamous self-pollination. Controlled pollination experiments were used to assess the effect of self- and cross- pollen and a pollen mixture from five unrelated parents on capsule and seed production, and on pollen tube growth in seven trees. Three trees in the experiment were self-incompatible, as quantified by the index of self-incompatibility (ISI), indicating that natural populations may consist of a mosaic of self-compatible and incompatible individuals. Self-incompatibility is late-acting as pollen tubes from selfs and crosses reached the ovary simultaneously at 10-15 d after pollination. In common with other Myrtaceae, the seed/ovule ratio in pohutukawa is low and this is likely to be genetically determined rather than limited by stigmatic pollen load. Germination of fertile seeds from all pollination treatments was equally high (98.4%), indicating that no inbreeding depression is acting at this stage of the life cycle. The pollen/ovule ratio of 462.5 (s.e. �43.3) places the breeding system of pohutukawa between facultative selfing and facultative outcrossing. en
dc.publisher Royal Society Of New Zealand en
dc.relation.ispartofseries New Zealand Journal of Botany en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from http://www.sherpa.ac.uk/romeo/issn/0028-825X/ en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.source.uri http://www.royalsociety.org.nz/publications/journals/nzjb/1999/059 en
dc.title Floral biology and breeding system of pohutukawa (Metrosideros excelsa, Myrtaceae) en
dc.type Journal Article en
dc.subject.marsden Fields of Research::270000 Biological Sciences::270400 Botany en
pubs.issue 4 en
pubs.begin-page 687 en
pubs.volume 37 en
dc.rights.holder Copyright: Royal Society of New Zealand en
pubs.end-page 702 en

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