The goal of this study was two fold, the first was to determine the effect of different basal medium formulationsand medium supplements (complex additives and growth hormones) on the development and growth rate of Phalaenopsis orchids, while the second goal was to find or develop an efficent method for the clonal propagation of Phalaenopsis orchids.MethodsThe first part of this study was further subdivided in to several phases; the first of these involved a comparative study of the germination of Phalaenopsis ovules on six different basal medium formulations and seven different sets of medium supplements. The second phase involved a comparative study of the development of Phalaenopsis protocorms on six different basal medium formulations and ninteen different sets of medium supplements. The third phase involved a comparative study of the growth of Phalaenopsis seedlings on six different basal medium formulations and twelve sets of medium supplements. The forth and final phase involved a comparative study of the development and growth of Phalaenopsis protocorms and seedlings on media containing varing concentrations and combinations of auxins and cytokinins. The second part of this study involved a comparative study designed-to determine the suitability of several sizes of axillary buds and plantlets for the clonal propagation of Phalaenopsis orchids and the modification of several procedures in an attempt to determine suitable explant material and procedures for the commercial clonal propagation of Phalaenopsis orchids.Results and DiscussionResults of this study indicated that of the basal medium formulations and medium supplements tested Modified Heller's salt base medium and to a lesser extent Modified Vacin and Went salt base medium supplemented with vitamin formulation 1 and Bactopeptone yielded the highest percent germination and development up to the seedling stage. At the seedling stage the growth rate of seedlings grown on media supplemented with banana homogenate nearly doubled the growth rate of the seedlings grown on all of the other medium supplementstested.Results of the second part of this study indicated that by modifying the procedures of Bouriquet, Broly, and Legrand (1982) the proliferation rate (shoots per plantlet) could be increased by a factor of two to eight. This can be translated into an increase from two to five shoots per plantlet per six weeks to an increase of eight shoots per plantlet per six weeks with a minimal mortality rate. With further modification of the procedure of Bouriquet, Broly, and Legrand (1982), other results indicated that it may be possible to increase to forty the number of shoots per plantlet produced per six week period. / Department of Biology

[Truncated abstract] Currently, Alcoa World Alumina Australia (Alcoa) mines and undertakes procedures to rehabilitate approximately 550 ha of jarrah forest each year at two open-cut bauxite mines in South-West Western Australia. Alcoa aims to establish a self-sustaining jarrah forest ecosystem that maintains the functions of the landscape prior to mining, including biodiversity, on areas that have been mined for bauxite. Indigenous terrestrial orchids form a significant proportion of the indigenous geophytic plant species that either fail to colonise rehabilitated areas or do so very slowly. Terrestrial orchids are considered to be particularly sensitive to competition from weeds and disturbance, which combined with the obligate nature of the orchid-mycorrhizal fungus association suggests that orchids would colonise rehabilitation areas only when both microhabitat sites and soil microflora have established. Occurrence of certain orchids may therefore be expected to be useful as indicators of ecosystem health, the success of vegetation establishment and the recovery of edaphic conditions suitable for orchid mycorrhizal fungi. Vegetation surveys were undertaken to compare orchid species richness and population size of a chrono-sequence of rehabilitation areas with adjacent unmined forest. ... Orchid taxa present in each vegetation assemblage were generally not exclusive to these assemblages, with the following broad exclusions: D. bracteata was found only in species assemblages associated with rehabilitation areas; and Eriochilus sp. and T. crinita were found only in species assemblages associated with unmined forest. No single orchid species appears to be an indicator of ecosystem recovery. However, the presence of populations of C. flava, P. sp. crinkled leaf (G.J.Keighery 13426) or P. recurva in combination with the absence of the disturbance opportunist orchid taxa D. bracteata and M. media appears to be a measure of the maturity of the rehabilitation vegetation. Orchid species richness and clonal orchid population size were correlated with changes in vegetation structure, but apart from the absence of orchids in 1 year old rehabilitation areas, these orchid population characteristics did not show any direct relationship with rehabilitation age or vegetation maturity. Only two orchid taxa appeared to have potential as indicators of vegetation characteristics: T. crinita as an indicator of undisturbed jarrah forest; and D. bracteata as an indicator of disturbed ecosystems. The results of this study suggest that most jarrah forest orchid taxa will readily colonise the post bauxite mining landscape, but that the unassisted colonisation by recalcitrant orchid taxa may be a prolonged process. It is recommended that field-based transplantation and/or seeding trials be undertaken with these recalcitrant taxa to determine if these procedures will enhance recruitment. The results of this work have applications not only in the management of post-mining landscapes but also in vegetation monitoring and conservation work in Western Australia and elsewhere.