Germination of selected Australian native grass species, with potential for minesite rehabilitation

Native grasses have become increasingly important in the post-mining landscape where land rehabilitators try to reconstruct vegetation communities similar to those present before land clearing. So as to include native grasses in these communities, there is a requirement to understand their germination biology, because in the past, many grasses have typically been hard to establish in the final community. The present study found that poor germination of 13 native grass species was due to (1) low percentage of seed fill, (2) low seed viability of filled seeds and/or (3) seed dormancy. Eight species had dormancy treatments investigated. Most were found to exhibit at least one form of dormancy that was either located in the hull structures immediately external to the caryopsis (i.e. the lemma, palea and glumes), within the seed coat (i.e. testa and pericarp, tissues that are found inside the hull, but external to the embryo and endosperm) and/or within the embryo. Seven of the grass species tested were found to have a dormancy mechanism present in two or more locations of their dispersal unit. Germination of the selected native grass species could be improved by (1) processing seeds to enrich the percentage of seeds that are filled, (2) testing viability to ensure a high proportion of the seeds are likely to germinate or (3) using methods to help overcome dormancy and promote germination.