Seed enhancement technologies to improve germination and emergence of Australian native Poaceae

Abstract

Using seeds to restore natural ecosystems has a greater chance of success if the seeds used are ready to germinate given appropriate environmental conditions. For Australian native Poaceae species, seed quality and dormancy can impose constraints on restoration success. In this study, germination biology of three Australian native Poaceae species, such as Cymbopogon refractus, Capillipedium spicigerum and Bothriochloa bladhii, was investigated. The seeds were exposed to different germination-enhancing chemicals (GECs, namely smoke water (SW), potassium nitrate (KNO3) or a combination (SW + KNO3)) and treated with three different seed enhancement technologies (SETs, namely seed priming, seed coating or seed cookies) then sown into two contrasting soil types (sodosol or black vertisol). Laboratory germination percentages achieved were <50% for all species, limited by dormant seeds. Incorporating GECs together with seed priming or seed coating treatment significantly increased seedling emergence rates and promoted earlier emergence as compared to the untreated control. For C. refractus and C. spicigerum, priming and/or coating with KNO3 + SW had the highest cumulative emergence. For B. bladhii, total seedling emergence was the highest (36% in both soils) for primed seeds with KNO3. Seedling emergence from seed cookies was low in all three species (<15%). Generally, soil type did not influence emergence rates for either GEC or SET. Understanding the environmental requirements needed for seed germination, together with an appropriate pre-treatment before sowing, can speed up seedling emergence and increase total emergence when using native Poaceae species for seed-based restoration.