Seed viability of native grasses is important when revegetating native wildlife habitat

Native grasses are a dynamic and essential component of the majority of terrestrial ecosystems in the Northern Territory. Restoring native grasses in disturbed environments is important for providing faunal habitat, reducing surface erosion and resisting weed invasion. However, establishing native grasses has been problematic in many regions of Australia due to seed viability issues. We investigated 48 seed lots of 29 Northern Territory native grass species to determine whether seed quality was an issue for establishment of tropical native grasses. Seed lots were largely collected by commercial seed suppliers, rather than by research staff, so the samples reflect seed lots that could be sourced for revegetation projects. The seed purity, proportions of filled seeds, visually viable seeds and metabolically active seeds were assessed. Viability responses to storage were investigated in 15 seed lots. The proportion of florets that contained a seed (caryopsis) ranged from 10-97% (average 62%) and between 0-79% of the florets contained metabolically active seeds (average 36%). Two seed lots had viability of 0-10% and 12 of the 48 seed lots had less than 30% seeds that were metabolically active and potentially viable. Thus, seed quality limits establishment of tropical native grasses from sown seeds in the Northern Territory. When using native grasses to establish native habitat it is important to assess the quality of the seeds and use a sufficient quantity of seeds for effective establishment of these grasses. Seeds of many species will maintain viability for several years if stored in cool dry conditions. Seed for revegetation projects can therefore be collected and stored over several years.