The future of the world's gene banks, set up as safe havens for humankind's agricultural heritage, is in jeopardy.
Research by scientists from Imperial College, Wye, found that many of the crop varieties stored in national collections could be lost unless action is taken.
The findings were presented yesterday at the Earth Summit in Johannesburg by Chris Higgins, professor of clinical science. They were delivered along with a call to support a $260 million (£169 million) endowment administered by the soon-to-be launched Global Conservation Trust to ensure the future of all gene banks in perpetuity.
Professor Higgins, a trustee of Future Harvest, a body that operates 16 international agricultural research centres, warned: "We have to maintain plant genetic diversity because it underpins our future. The only place to do this is with gene banks but these are in a parlous state."
In 10,000 years of agriculture, 50,000 varieties of crop have been cultivated around the world. Many contain genes that make them suited to particular environments and needs.
Scientists argue that this diversity could be mined to produce future crops with the high yields demanded by the world's growing population or the ability to cope with climate change and environmental threats.
The range of crops grown by farmers has fallen sharply in the past century, while land clearance and urban sprawl threaten many of the original wild species.
Researchers led by Jeff Waage, professor of applied ecology and head of agricultural sciences at Imperial College, Wye, used data collected by the United Nations food and agriculture organisation to determine the health of the world's 1,470 gene banks and 5.4 million plant samples they hold.
They found that a quarter of countries housing collections had cut back on funding despite a 66 per cent rise in the overall number of plant samples conserved in the past five years.
Some were kept as growing plants, others as dried seed or frozen cells. But all require maintenance.
Many reported that their samples urgently needed to be grown out and new seed harvested before they lost the ability to germinate.
But without adequate funding, particularly in the developing world, it was difficult to prevent collections from deteriorating.
The Global Conservation Trust will raise money from governments and organisations to provide the means to maintain and build the capacity of the world's most critical plant collections.