The role of after-ripening in promoting germination of arid zone seeds: a study on six Australian species

Abstract

The effects of after-ripening (storage under warm, dry conditions) on seed germination was examined in six plant species from the arid zone of Western Australia with the aim of improving germination and germination rate for rehabilitation objectives. Study species (Acanthocarpus preissii, Anthocercis littorea, Dioscorea hastifolia, Eremophila oldfieldii, Thryptomene baeckeacea and Zygophyllum fruticulosum) were selected based on diverse plant habits, seed types and requirements for rehabilitation. After-ripening was investigated by adjusting seed moisture content to 13 and 50 equilibrium relative humidity (eRH) at 23°C and storing seeds at two temperatures (30 and 45°C) from 1 to 18 months. Following storage, seeds were incubated in water, gibberellic acid (GA3) or karrikinolide (KAR1; the butenolide, 3-methyl-2H-furo[2,3-c]pyran-2-one). All after-ripening conditions increased germination percentage and rate of A. littorea and D. hastifolia, with A. littorea only germinating when treated with GA3 or KAR1. The germination of Z. fruticulosum was dependent on after-ripening temperature and seed moisture content. After-ripening had a limited effect on the remaining three species. The restoration implications of the findings are discussed.

Overcoming physiological dormancy in seeds of Triodia (Poaceae) to improve restoration in the arid zone

“…seeds were hydrated for 2 days, then redried for 28 days) significantly enhanced germination to 100% after the same storage time (Hoyle et al 2008 a ). In another study on arid zone species, Commander et al (2009 a ) assessed various combinations of relative humidity and storage temperatures, and found, for example, that dormancy loss of Dioscorea hastifolia seeds was significantly faster at 45°C than at 30°C. Such studies highlight the role that storage temperature and seed water content plays in DAR.…”

“…Such studies highlight the role that storage temperature and seed water content plays in DAR. Storing florets or seeds under differing environmental conditions, including exposure to treatments such as wet/dry cycling and/or chemical stimulants (Commander et al 2009 a ; Hidayati et al ), may assist in further refining dormancy break of Triodia , particularly those species that have not responded to the DAR conditions imposed in this study.…”

“…In another study on arid zone species, Commander et al (2009a) assessed various combinations of relative humidity and storage temperatures, and found, for example, that dormancy loss of Dioscorea hastifolia seeds was significantly faster at 45 ∘ C than at 30 ∘ C. Such studies highlight the role that storage temperature and seed water content plays in DAR. Storing florets or seeds under differing environmental conditions, including exposure to treatments such as wet/dry cycling and/or chemical stimulants (Commander et al 2009a;Hidayati et al 2012), may assist in further refining dormancy break of Triodia, particularly those species that have not responded to the DAR conditions imposed in this study.…”

Comparative longevity of Australian orchid (Orchidaceae) seeds under experimental and low temperature storage conditions

“…More specifically, endospermic seeds tended to be shorter lived than non‐endospermic seeds and species originating in hot, dry climates were longer lived than those from cool, wet climates. Commander et al. (2009), among others, have demonstrated that many species from desert environments are dormant at maturity and may require after ripening to increase germination percentages.…”

Setting the scene for dryland recovery: an overview and key findings from a workshop targeting seed‐based restoration

“…Some examples include the use of mechanical or chemical abrasion, wet or dry heat, dry after‐ripening, warm and cold stratification, and the use of chemical stimulants (e.g. gibberellic acid, karrikinolide, and ethylene) (Hargurdeep et al ; Morris ; Bonner & Karrfalt ; Commander et al 2009 a , 2009 b ; Turner et al ; Kildisheva et al ; Baskin & Baskin ; Erickson et al 2016 a ). A number of dormancy alleviation techniques have been successfully applied in the context of large‐scale restoration (Rokich et al ; Rokich & Dixon ; Erickson et al 2016 a ).…”