Liu Huaizhi, a farmer in his 70s, never thought that a variety of corn his family had planted for over a century could one day become a national treasure.

Living in a remote mountainous area of Yicheng County, north China's Shanxi Province, Liu plants a variety of corn that features tiny cobs, bulbous grains and low annual yields.

"It's not for economic returns," Liu said, as popcorn made from the corn sweetens his family's life.

Heated in a covered pot, over 99 percent of kernels made from Liu's corn variety burst into popcorn dozens of times larger than the original size, researchers later found.

Named "pearl corn," the variety was discovered during the country's ongoing large-scale germplasm census, which aims to protect endangered resources nationwide and explore new ones.

Local crop species are facing mounting risks of extinction brought by accelerating industrialization and urbanization, climate change, as well as agricultural transformation, and that could affect biodiversity, according to the census action plan.

Treasures like pearl corn that were discovered in the course of the census will be kept in reserve in the national germplasm bank at the Chinese Academy of Agricultural Sciences, which boasts the world's largest capacity at 1.5 million units.

"The germplasm bank forms one of the significant foundations of the seed industry, with the key task of making agricultural technological breakthroughs during the 14th Five-Year Plan period (2021-2025)," according to Minister of Agriculture and Rural Affairs Tang Renjian.

To further enrich the country's germplasm bank, people from fields such as germplasm resources, plant classification, biological breeding, and information technology have been trained as "seed hunters," or census takers.

Li Xuefeng, one of the census takers to discover the pearl corn, still remembers the arduous journeys taken day after day. The census team would pack instant noodles and set out at dawn each day, and then they would walk dozens of kilometers, braving the danger of falling from the cliffs.

"The discovery and preservation of pearl corn was a rare event," Li said. It was when the sun was about to set one night that the census team heard about the variety. Regardless of their tiredness during the daytime, they began seeking it at once.

Older generations had told Liu that "corn with tiny cobs is too timid to stand close to corn with big cobs," so he always plants the special variety on its own atop a hill to prevent the mixture of pollens.

"Without the germplasm census, it is unlikely that pearl corn would have been discovered and it could have disappeared years later," Li said, noting that the variety has various advantages such as stronger resistance to pests and crop diseases, and it is higher in calcium.

Li is one among millions of census takers with a passion for remote mountains and forests, as farmers on plains usually use commodity seeds to achieve scale production.

"We keep moving forward through twists and turns," said Chen Jiying, a census taker in southwest China's Yunnan Province. The sweet taste and soft texture of a special type of yam she found in a remote village are still fresh in her mind.

"No matter how winding the trail, we feel happy as long as we can find something that contributes," Chen said.

In the newly unveiled "No. 1 central document," the first policy statement released by China's central authorities this year, the country outlined seed industry development as one of its policy priorities, which means China's seed hunters will soldier on in their search.

Although the work is time-consuming, laborious and doesn't yield fruit easily, seed hunters share the belief that "someone must do it" as their work can benefit future generations.