This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Cite this article
Arnold S, Kailichova Y, Baumgartl T.2013. Germination of Acacia harpophylla (Brigalow) seeds in relation to soil water potential: Implications for rehabilitation of a threatened ecosystem. PeerJ PrePrints1:e100v1https://doi.org/10.7287/peerj.preprints.100v1
Initial soil water conditions play a critical role when seeding is the primary approach of revegetation on post-mining areas. In some semi-arid climates, such as the Brigalow Belt Bioregion in eastern Australia, extensive areas are affected by surface mine developments. Together with erratic rainfall patterns and clayey soils water deficit is the primary environmental stressor, which makes the Brigalow Belt representative for other water-limited ecosystems worldwide. Apart from other environmental stressors germination is governed by the water potential of the surrounding soil material. While previous studies confirmed the high tolerance of Brigalow (Acacia harpophylla) seeds to a broad range of temperature and salinity, the question remains how soil water potential triggers seed germination. In this study, we used three replicates of 50 seeds of predominant native Brigalow to investigate germination in relation to water potential as environmental stressor. Solutions of Polyethylene Glycol (PEG 6000) were applied to expose seeds to nine osmotic water potentials ranging from soil water saturation (0 kPa) and field capacity (-10 to -30 kPa) to the permanent wilting point (-1,500 kPa). We measured germinability (number of germinated seeds relative to total number of seeds per lot) and mean germination time (mean time required for maximum germination of a seed lot) to quantify germination. Based on these empirical data we estimated the parameters of the hydrotime model, which facilitates to simulate timing and success of seed emergence. Our findings indicate that Brigalow seeds are remarkably water stress tolerant with germination being observed at a water potential as low as -1,500 kPa. Likewise, the average base water potential of a seed population (hydrotime model) was very low and ranged between -1,533 kPa and -1,451 kPa. In general, Brigalow seeds germinate opportunistically over a broad range of abiotic conditions related to temperature, salinity, and water availability. Direct seeding and germination of native plants on post-mining land may be an effective and economically viable solution in order to re-establish plant communities. However, due to their ability of asexual reproduction, alternative rehabilitation approaches such as transplantation of whole soil-root compartments may become attractive for restoration ecologists to achieve safe, stable, and non-polluting ecosystems.
This manuscript has been submitted for review with PeerJ.