Seed biology can inform conservation actions: a case study on Geijera parviflora

Abstract

Context

Knowledge of seed biology is imperative for effective curation and utilisation of seeds.

Aims

We studied the seed biology and reproduction of Geijera parviflora, a species suitable for ecological restoration and ornamental horticulture that has largely been overlooked because of issues with unreliable germination and viability.

Methods

Germination in response to dormancy-breaking treatments and soil seed burial, and variation in germination at an inter-population level were assessed for G. parviflora. Seed storability in a conventional seedbank was tested. Floral phenology was assessed.

Key results

Germination of untreated and seed coat removed seeds were 0 ± 0.0% and 67 ± 5.5% respectively. Seed germination varied between 21.9 ± 1.8 and 66.6 ± 5.5% at an inter-population level. Seeds buried in soil for 6 months showed 11.7 ± 0.8% germination without any treatment. All seeds buried for 12 months were non-viable. Drying seeds from 11.4 ± 0.19% to 5.79 ± 0.17% moisture content resulted in 40% less germination. Visual observation of floral attributes confirmed the presence of orange-coloured pollen grains for 3.5 ± 0.48 days from floral opening. The stigmatic surface became shiny 3.5 ± 0.21 days after floral opening.

Conclusion

Seeds of G. parviflora demonstrate physiological dormancy; treatments that remove seed coat resistance against embryo growth enable germination. Local environmental conditions may explain the inter-population variation in germination. Seeds are short-lived in soil and ex situ seedbank conditions. In soil, seeds release dormancy at the end of first winter, so seeds are available to germinate the following spring/summer with high rainfall. Floral phenology assessment indicated protandrous sequential hermaphroditism, which may reduce the probability of self-pollination in G. parviflora.

Implications

This knowledge supports use of G. parviflora in ecological restoration and horticulture.