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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.

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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.

The accumulation of free proline in the flrst leaves of barley, Hordeum distichum L., and wheat, Triticum aestivum L.. in response to a range of low temperatures was examined with 10-dayold plants. In barley (cv. Prior) no proline accumulated at 8°C or above, but in wheat (cv. Gabo) proline accumulated at 12°C and lower temperatures. In barley, the first leaf survived for 29 days following transfer to 5°C and continued to accumulate proline throughout this period. In contrast, the first leaves of plants maintained at 20° C survived for 13 days only and accumulated no proline. Proline accumulation at low temperature was shown to be light-dependent, both in intact plants and excised leaf sections, and the light requirement could not be replaced by supplying leaf segments with precursors of proline. Proline accumulation in response to water stress was not light-dependent at 20°C but was at 5°C.Inter-specific and intraspecific variation in the extent of accumulation in response to low temperature was also examined. Considerable variation was encountered but there was no clear relationship with geographical distribution or chilling sensitivity for the species and no correlation with accumulation in response to water stress in the cultivars of barley examined. ' Present address:

Allozyme electrophoresis was used to determine the extent of clonality in four naturally occurring populations of Acanthocladium dockeri F.Muell. from the mid-north of South Australia. A total of 33 loci was scored for at least 16 plants from each population. The four known populations of A. dockeri represent four quite distinct genetic clones. Each natural population consists of a single genet, and no indication of any correlation between geographical proximity and genetic similarity was found. Seed set in flowers was very low (0.6% of florets), probably owing to low pollen germinability. Seedlings raised from A. dockeri seed collected at Hart displayed obvious genetic affinities to their parent, but were nevertheless genetically distinct. Differences were consistent with the derivation of this seed by selfing of the Hart genet. A. dockeri is considered at high risk of extinction because of its low genetic diversity, poor seed production, lack of seedling recruitment and population growth by clonal reproduction alone. On the basis of the outcomes of this research, the following recommendations for conservation management of A. dockeri are made: (1) all four extant genets should be preserved in their respective habitats; (2) at least one ex situ collection of all four extant genets should be maintained at a secure site as an insurance against population loss; (3) further surveys are required to potentially locate new populations with superior fertility; and (4) mixing of clones or seed provenances into a single population should be avoided until appropriately designed experimental translocations have evaluated the possible consequences of such mixing on competitive, reproductive and genetic responses of populations.

Glasshouse and field trials were conducted to select plant species suitable for revegetation of waste fly ash lagoons. Species which demonstrated potential for growth on fly ash or ameliorated fly ash m glasshouse trials were subsequently tested by direct seeding in situ at the Port Augusta power station in South Australia. Xero and halophytes from the families Aizoaceae, Chenopodiaceae and Zygophyllaceae performed optimally in both sets of trials, and species most suited for revegetation and regeneration included Mesembryanthemum aitonis, M. nodiflorum, Atriplex holocarpa, A. lindleyi, A. vesicaria, Enchylaena tomentosa, Halosarcia halocnemoides, H. pergranulata, Scaevola collaris and Nitraria billardierei . A range of surface amelioration treatments for fly ash lagoons designed to overcome the chemical and physical limitations of fly ash to plant growth, and to reduce the effects of high temperatures, strong winds and low rainfall in the region were also tested. A 50-100-mm surface cover (overlay) of either local sandy topsoil or compost, stabilized with coarse organic mulch, hydromulch or erosion control fabric supported good germination and plant growth. The soil or compost overlay provided a seed bed for initial germination away from the toxic elements of the ash, while the stabilization treatment prevented wind-blown removal of both seed and seed bed, while also conferring some protection to germinating seedlings. © 1997 ISWA

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