Variation in germination, in responce to salinity and waterlogging and the link with seed tree habitat of ten australian native species

Abstract

It was observed over several years of monitoring Landcare plantings that a number of locally-occurring native species showed variation in seedling establishment, particularly on degraded soils in the Upper Shoalhaven Catchment, a region of extreme frost. The variation appeared to be linked to different seed source locations. The question arose of whether habitat adaptation was occurring and, if it was leading to biodiversity within local species. This was key information needed for seed source selection in rehabilitation projects, for degraded soils on the Southern Tablelands of NSW. The primary aim of this research project was to investigate whether or not habitat differences in parent trees could be linked to measurable differences in the waterlogging and salinity tolerances of their progeny. The germination experiment was proposed as a method for investigating variation within local species, measuring germination rates under six different treatments of salinity and waterlogging. Populations of ten native tree and shrub species were selected for trial and seed was sourced from seven different habitat types in the Upper Shoalhaven Catchment and neighbouring areas, within a 100km radius of Braidwood, NSW. Glasshouse experiments were conducted over a six week period, from November to December. Experiments included a saline treatment with addition of a biofertiliser called 'PuraCast', a microbiologically active liquid, derived from worm castings. Species investigated were: Eucalyptus ovata, E.pauciflora, E.dives, E.blakelyi, E.aggregata, Acacia melanoxylon, A.decurrens, Casuarina littoralis, C.stricta, Leptospermum flavescens. There was a highly significant difference found between parent tree habitat and the germination response of progeny, particularly to treatments of medium salinity, waterlogging and waterlogging with salinity (P<0.001 in most cases). There was a moderately significant interaction between treatment and parent habitat type, with highly saline habitats, waterlogged and acidic soils producing seedlings tolerant of high salinity and combination treatments (P<0.05). Response to the biofertiliser was varied and further research is warranted for all of the above.