Planting for the future

Cai says that such painful encounters are part of their job, but each seed collection experience is precious. "I often think that if we missed saving one species, it would face extinction. What a tremendous loss that would be."

To ensure genetic diversity, researchers gather seeds from various locations where the same plant species grows.

Ideally, they try to collect 10,000 mature and plump seeds per sample, or a minimum of 2,500 seeds. However, it is crucial to ensure that the collection does not exceed 20 percent of the seeds available in the original population to avoid jeopardizing regeneration.

To better protect these rare seeds and assist in future ecological restoration, researchers record detailed information, such as collection time, location, altitude, soil type and surrounding environment. They also preserve the plants' twigs with leaves, flowers and fruits as herbarium vouchers to create a "DNA ID" for the seeds in the future.

"The DNA ID provides a molecular genetic pedigree for the accurate conservation of species in our country, and lays a solid foundation for future germplasm use and ecological restoration," Cai says.

The seeds must undergo procedures such as drying, cleaning and counting, before they can be stored. Ordinary seeds, such as corn and wheat, can be stored at room temperature for up to two years. To extend storage time, low temperature and dry conditions are used to prolong the seed's life span.

"Some seeds are incredibly small, like those from certain orchid plants, which are only tens of micrometers in size. Cleaning these seeds presents a significant challenge, not to mention counting them accurately," says Qin Shaofa, a seed curation supervisor at the germplasm bank.

Due to static electricity in the drying room, seeds from orchid plants often stick to weighing instruments, making them difficult to remove.

"To avoid losses, we only extract a portion of the seeds for weighing, calculate the average weight, and determine the number of seeds by weighing the total," Qin explains.

Before counting the seeds, a random sample is taken and examined using an X-ray machine, so scientists can easily see whether the seeds are plump or shriveled.

After examination, the seeds undergo another round of cleaning, quality testing, counting and drying. They are then stored at 15 C with a balanced relative humidity of 15 percent for one month to induce dormancy.

Finally, after being sorted into sealed containers according to size, the seeds enter their hibernation stage in cold storage at — 20 C.

Each species' seeds are divided into two parts: the first stored in the basic repository for permanent preservation, and the other in the active repository for germination testing and research purposes, Qin says.