Key outcomes of the Conservation Seed Science team:
Modelling of the seed longevity of more than 200 native species demonstrates that seed life-spans vary between species by at least four orders of magnitude. This data is being used to assess potential plant ecological and seed morphological traits that may assist in predicting whether species produce long- or short-lived seeds. Seeds of serotinous species, and those that possess physical dormancy ('hard-seeded' species), tend to be long-lived. Seeds of orchids are very short-lived and require specialised storage procedures including cryopreservation for effective long-term conservation.
Warm stratification (incubation of seeds under warm, moist conditions) is an effective means of dormancy alleviation for many species that are difficult to germinate. The application of alternating wetting/drying cycles during warm stratification accelerates this dormancy loss for some species, including those of the much sought-after genus Hibbertia. The sensitivity of seeds to smoke and karrikinolide is, in part, dictated by the application of these dormancy alleviation treatments.
Research on the enigmatic aquatic plant family Hydatellaceae, recently re-classified as a member of an ancient group of basal angiosperms, has found that these seeds have an unusual and previously undiscovered means of germination. The tiny seeds of Trithuria species have a new kind of specialised morphophysiological dormancy. During the germination process, the undifferentiated cells of the embryo do not differentiate into either a radicle or a shoot until after the embryo emerges from the seed coat. It is thought that this primitive and somewhat risky means of germination is possible only due to the aquatic habitat of these plants.
Molecular research in collaboration with colleagues at The University of Western Australia’s (UWA) School of Chemistry and Biochemistry has established signalling proteins responsible for karrikin action in seeds. Methods have been established for the synthesis of labelled karrikins to research the fate of these molecules in seeds and in the environment, and improved methods for production of karrikins from simple carbohydrates have been developed. These chemical and molecular studies are being used to support ecological studies through investigating the stability and efficacy of karrikins in soil to promote seedling emergence at restoration sites and for broad-acre weed control.
Collaborative research with UWA’s School of Chemistry and Biochemistry has identified a second germination-active chemical in smoke from the cyanohydrin group of chemicals. Under certain conditions cyanohydrins slowly release cyanide, a compound long known to promote germination. This ground-breaking research provides for the first time an ecological explanation for the seed response to cyanide.
Studies on prominent agricultural weeds, including those of the Brassicaceae, are being undertaken to develop the application of karrikinolide for broad-acre weed control. The germination response to karrikinolide is now know to be species and seed-lot specific and strongly influenced by seed hydration status. This provides important insights into factors influencing weed emergence in response to karrikinolide, guiding the optimal timing of karrikinolide application to the soil.