Seed ecology of Lepidosperma scabrum (Cyperaceae), a dryland sedge from Western Australia with physiological seed dormancy.

摘要

Lepidosperma scabrum is a common understorey species currently required for urban bushland restoration, although its propagation has been highly problematic. In this context, the overall aims of the present study were to (1) document key characteristics for seed-dormancy classification; (2) assess the effectiveness of different germination-promoting treatments; and (3) quantify changes in nutlet fill, dormancy and germination following soil storage under natural and nursery conditions. Initial investigations found that naturally shed nutlets (the natural germination unit) have high seed fill and viability (>90.0%) and a small (~468 micro m) capitate embryo that readily grew (>95.0%) when extracted and cultured in vitro. Intact nutlets also imbibed moisture to a similar percentage (15.0+or-1.4%) as nicked nutlets (18.0+or-1.8%). Fresh nutlets germinated only in response to heat shock (100 degrees C for 10 min), which was enhanced with additional treatment with 2.89 mM gibberellic acid (13.3%), 10% v/v smoke water (16. 6%) or a combination of both (23.3%). Nutlets placed into a burial trial maintained viability for 3 years and started to germinate (19.9+or-9.5%) in response to smoke water by the third winter season. Heat shock was also found to significantly improve germination (81.1+or-4.2%) for soil-aged nutlets. The present study is the first report of high germination from intact nutlets of any Lepidosperma spp. and provides practical techniques for the large-scale production of plants for horticulture and restoration.