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Syzygium maire (swamp maire) is an endemic New Zealand Myrtaceae tree species. Current threats to this species include habitat destruction, myrtle rust, declining remnant populations and low capacity for natural regeneration. Large-scale replanting for conservation/restoration initiatives would mitigate against these threats. However, there is limited information available on propagation of this species. In this study, we looked at sexual propagation using seed germination and asexual propagation using softwood cuttings. For seed germination, we examined the effect of seed pretreatments (intact fruit or de-pulped seed) and temperature settings (15/25°C or 20/30°C) to optimise germination. For softwood cutting propagation, we investigated the diameter of the cuttings (1–2 mm or 3–5 mm) and application of exogenous indole-3-butyric acid (IBA) (0, 1.5, 3.0, or 4.5 g L−1) on their efficacy of producing adventitious rooting. The most critical factor for seed germination was the removal of seed pulp. De-pulping the seeds shortened the mean time to germination and positively affected the germination percentage, regardless of the incubation temperature. Germination percentage of ≥94.5% was achieved in seeds sown without pulp. Propagation by softwood cutting of 1–2 mm in diameter was possible without IBA treatment (63.3% of cuttings rooted), but the application of 1.5 g L−1 IBA increased the rooting percentage (to 75%), thereby inducing the production of a higher number of roots. Seed germination and softwood cutting were effective strategies to propagate S. maire. The findings of this research contribute to the knowledge of propagation and restoration of S. maire populations. [ABSTRACT FROM AUTHOR]

Syzygium maire is an endemic tree in New Zealand and classified as critically endangered. The in situ populations of this species are further threatened by the incursion of myrtle rust. The biology and ecology of S. maire have not been well documented and limited information on seed development, effective germination and seed storage behaviour of S. maire are hampering ex situ conservation and restoration. In this study, we investigated fruit and seed development on S. maire populations growing at four sites and in different seasons, and used short-term seed storage protocols to investigate the storage potential of harvested seeds. Fruit development took 8–11 months with three of the four identified stages occurring during the warmer spring and summer months. Embryos were found to be viable from stage two, but seedlings from final stage embryos were more robust. The moisture content of the fruit pulp varied between populations and within populations between seasons, but embryo moisture content remained more constant. S. maire seeds have high germinability when removed from the fruit pulp, and removal from the pulp is essential for germination. Seeds in fruits stored hydrated at 5°C remained viable for up to 12 weeks, although some germination was observed from eight weeks. This paper identifies optimal time for seed collection to ensure high quality seed for propagation and restoration while the short term storage provides an opportunity for further research into long term seed conservation through cryopreservation. [ABSTRACT FROM AUTHOR]

The current threat of myrtle rust (Austropuccinia psidii) to New Zealand Myrtaceae, including a number of indigenous and socio-economically important species, requires that ex situ conservation is used to complement in situ populations. New Zealand's Myrtaceae have received little attention in terms of ex situ conservation. In this study, we assessed the integrated ex situ conservation strategies for selected New Zealand Myrtaceae. We particularly investigated seed banking options by assessing seed desiccation tolerance, in vitro culture, pollen cryopreservation and zygotic embryo cryopreservation of the recalcitrant Syzygium maire. A desiccation trial was conducted on six Myrtaceae species: Lophomyrtus bullata, L. obcordata, Metrosideros diffusa, M. umbellata, M. bartlettii and Syzygium maire. S. maire seeds and embryos showed extreme sensitivity to desiccation confirming its recalcitrant behaviour. The seeds of the other species were desiccation tolerant i.e. orthodox. Zygotic embryos of S. maire were successfully cryopreserved using an encapsulation-dehydration technique. Pollen cryopreservation was successful for M. excelsa following desiccation to about 5% moisture content, rapid freezing and rapid thawing. For M. bartlettii, one of the most endangered and a nationally critical Myrtaceae species in New Zealand, we tested the efficacy of hand pollination in producing viable seeds. Our assessment confirmed that one of the M. bartlettii trees at Otari is self-incompatible, and successful hand pollination using pollen obtained from different genotypes growing in the gardens at the University of Auckland resulted in seed production with c. 20% germination. Tissue culture protocols were successfully developed for selected Myrtaceae. In addition, photoautotrophic micropropagation techniques were developed for the first time for L. scoparium. This paper highlights the importance of holistic conservation strategies to ensure future access to New Zealand's unique Myrtaceae germplasm as a key component of long-term management response to the threat posed by A. psidii. [ABSTRACT FROM AUTHOR]

Chatham Island forget-me-notMyosotidium hortensia(Boraginaceae) is a monotypic genus endemic to the Chatham Islands of New Zealand.Myosotidium hortensiais threatened in its natural environment by introduced grazing animals and weeds. Further to this, the conservation and reintroduction efforts ofM. hortensiaare hindered by their dormant seeds. The dormancy is imposed by the seed coat but the underlying dormancy mechanisms are not well understood. Understanding the dormancy mechanisms in this species will help in revegetation efforts. This work aims to elucidate mechanisms by which the seed coat imposes dormancy inM.hortensiaby determining the germination after manipulation of the seed coat and measuring changes in oxygen uptake in response to this manipulation. The structure of the seed coat was assessed using scanning electron microscopy and the presence or absence of lignin in the seed coat determined. As with other Boraginaceae, the seed coat ofM.hortensiadoes not restrict water penetration into the seed. Oxygen uptake was 4.5 fold higher in decoated than in intact seed. There was no significant increase in oxygen uptake for the seeds when their seed coat had been pierced or pierced and resealed with vaseline. However, the germination rate, as measured by radicle emergence, was faster in these seeds. These findings, in addition to the structural analysis of the seed coat which revealed that the seeds have secondary thickening but no lignin, confirmed that mechanical constraint of embryo growth was preventing germination. [ABSTRACT FROM AUTHOR]