World’s rarest plants, vital crops can’t be banked, says study

PARIS: International efforts to save some of the world’s rarest and economically important plants from climate change are doomed to fail because their seeds cannot be stored, researchers warned on Friday.

As the planet heats and mankind continues to decimate natural habitats, scientists concede that the only way to save some types of vegetation is in seed banks — giant repositories of thousands of species preserved for future generations.

Nations agreed a global strategy in 2002 to conserve at least three quarters of threatened plant species with the aim of recovering and restoring their stocks in nature at some point.

Scientists working in several seed banks around the world currently conserve seeds by drying them before freezing.

But new research by botanists at Britain’s Royal Botanic Gardens, Kew, found that 36 per cent of “critically endangered” plants and trees aren’t bankable under the current method because their seeds die when dried and so cannot be preserved by freezing.

“You can’t dry the seeds so you cannot conserve them in a conventional seed bank,” John Dickie, head of collections at Kew, said.

It was previously known that at least eight per cent of plants — including oak trees, mango, avocado and cacao — produce “recalcitrant” seeds that die when dried. But with seed banking a work in progress, only a small proportion of plants have had their suitability for freezing assessed.

Dickie and his team developed a model using data on the climate, species habitat and the known seed-storage behaviour of related vegetation that predicted how likely it was that a plant’s seeds would be bankable.

The analysis showed that the goal of conserving 75 per cent of the world’s threatened plant species outside their natural habitat by 2020 was “practically impossible”.

In addition, even a proportion of seeds that survive drying and freezing have been shown to deteriorate while in storage, further complicating efforts to save their species.

Dickie said the team at Kew, which has been banking seeds for nearly 40 years, noticed “declines in viability” in some seed varieties over the decades, meaning they are less likely to be successfully planted and grown in future.

Other common food plants with problematic seeds include lychees, jack fruit and coconuts — all from the tropics. Ebony, parana pine and myrtle trees also have “recalcitrant” seeds.