No abstract

Determining the seed quality and germination requirements for threatened orchid species in storage is vital for future conservation efforts. Seeds of many Australian terrestrial orchid species are held in conservation collections around the country, but few have been germinated in vitro, fuelling concerns over their long-term viability. This study tested three methods of assessing orchid seed quality; asymbiotic germination was compared with vital staining using triphenyltetrazolium chloride or fluorescein diacetate. Six culture media were examined for efficacy in promoting asymbiotic seed germination of four Australian terrestrial orchid species (Pterostylis nutans, Microtis arenaria, Thelymitra pauciflora and Prasophyllum pruinosum). Germination occurred on all media but germination rates were consistently highest on BM1 and development was most advanced on BM1, P723 and Malmgren media. Subsequent trials tested the efficacy of BM1 for asymbiotic germination of additional genera (Caladenia, Calochilus and Diuris), several congeneric species, and two species collected from several different provenances within each of their ranges. The results indicate that asymbiotic germination on BM1 medium is an effective technique for testing the performance of Australian terrestrial orchid seeds. The efficacy of vital stains to determine seed viability, however, remains uncertain, as significant disagreement between degree of staining and germinability was observed for some species.

No abstract

This paper was prepared to highlight some of the factors limiting the success of plant translocations, based on Manfred's work with experimental translocations of endangered plants in South Australia. Summary Experimental translocations of three endangered plants undertaken in SouthAustralia confirmed the impact of specific factors thought to affect the survival and establishment of seedlings of each species. A trial involving Prostanthera eurybioides planted into several different microsites, found microsite to be a critical determinant of survival and growth. Herbivore grazing and weed competition adversely affected survival and growth of Acacia cretacea and Acacia whibleyana translocants, respectively. While these findings may not necessarily extrapolate to all species, common sense suggests that these three factors should be important considerations when planning other plant translocations. For example, attention needs to be given to the exact placement of individuals in relation to suitable edaphic, biotic and climatic factors around the receptor site. Where weeds threaten the population, they need to be controlled either before or at the time of planting. Furthermore, protection of new plantings from herbivores is likely to be crucial, particularly during the first few months after planting.