Wild rice seeds need months of drying before they'll sprout
Sajeevan T, Wijayasinghe MM, Jayasuriya KMGG, Corli A, Hay FR
Seed Saving
If you save seeds from your garden, this is a reminder that dormancy isn't laziness: some seeds are hardwired to wait out exactly the kind of weather that would kill a seedling, and skipping that wait (or getting the timing wrong as rainfall patterns shift) can mean no germination at all.
Two wild rice relatives that grow in Sri Lanka won't sprout right after their seeds drop, even when there's water around, because germinating too soon could mean dying in a drought. Scientists found that drying the seeds out for up to a year breaks their dormancy and lets them sprout, but the two species react very differently to flooding: a short soak helps one species germinate better, while flooding does nothing for the other. That difference seems to match where each plant naturally grows, and heavier rains predicted under climate change could make it harder for the rarer species to ever get its dry spell.
Key Findings
Germination rose to about 80% in both species after up to 12 months of dry storage at 25°C and 60% relative humidity.
Beyond 12 months, germination dropped in O. rhizomatis and fell to zero in O. nivara.
A one-week flood boosted germination in O. rhizomatis, but 2-4 weeks of flooding suppressed it; flooding had no effect on O. nivara at any duration.
chevron_right Technical Summary
Two rare wild rice species from Sri Lanka use opposite strategies to time their seed germination to seasonal drought and flooding, and climate change's wetter forecasts could threaten the rarer of the two by disrupting the drying period its seeds need to wake up.
Abstract Preview
Original paper
Comparative seed dormancy and germination responses to drying and flooding in two Sri Lankan wild rice species.
Sri Lankan wild rice, Oryza nivara and Oryza rhizomatis, are two threatened species occurring in habitats with contrasting dry and wet seasonal patterns. Both species produce dormant seeds at dispe...
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Wild rice, also called manoomin, mnomen, psíŋ, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus Zizania, and the grain that can be harvested from them. The grain was historically and is still gathered and eaten in North America and, to a lesser extent...