This photo taken on Dec. 9, 2024 shows space-bred highland forage in Cona, southwest China's Xizang autonomous region. [Xinhua/Wang Zehao]

LHASA -- In the world's highest plateau region, the seeds of certain high-quality pasture grasses have been sourced from a place far higher than their growing altitude -- beyond the skies.

It all began when Losang Norbu, an agricultural official from Cona city in the southeastern part of the Himalayan mountain range, realized that improving local herders' livestock yields required better forage, a challenge further complicated by the region's harsh climate.

Ranging from 2,400 to 4,400 meters in elevation, Cona features a diverse landscape, from lush forests and alpine meadows to barren hillside fields.

Later, a cadre sent to support Southwest China's Xizang autonomous region as part of a paired-up assistance program had an idea: why not experiment with seeds from an even higher altitude? He proposed a joint space-breeding study for saline-alkali-tolerant forage grasses in cold, arid regions.

"I was thrilled to learn of Cona's plan to test our space-grown seeds," said Guo Rui, director of Shaanxi provincial space breeding engineering technology research center. "Although space breeding is widely adopted, it had never been tried on the snowy plateau until now."

Space breeding involves sending seeds into space aboard returnable satellites or spacecraft to expose them to conditions like high vacuum, microgravity and cosmic radiation, which randomly cause genetic mutations.

Back on Earth, scientists select seeds with beneficial traits -- such as high yield, superior quality, early ripening and disease resistance -- and cultivate them into new crop varieties.

The two parties immediately agreed. In early May, Guo, 56, headed a team to Cona for an on-site assessment and obtained some soil samples for subsequent analysis back at the lab.

Using these soil samples, the team tailored organic fertilizers, optimized for space-bred seeds to be used in the high-altitude environment.

About a month later, they rushed back to Cona, since the cold-resistant plants must be sown before the end of the frost-free period that lasts only over 40 days there.

The team opted to conduct the trial on a barren 2.5-hectare plot of neglected, sloping land. "Our goal was to perform an extreme test," said Guo. "If these seeds can thrive in the poorest conditions, they will be well-suited to the natural environments across a broader part of Xizang."

The team chose six space-bred forages, including broadleaf chicory and string-leaf rosin, for their cold resistance, disease resistance, and high nutrition and yield. The seeds ventured into space via Shenzhou-15 and Shenzhou-16 manned spacecraft.

Their successful cultivation could significantly boost feed production, helping to address the grass-to-livestock balance issue.

Guo's team prepared the land and set up a greenhouse nursery to analyze the growth of the seedlings. Yuan Zhongquan, 66, the oldest member of the team, endured altitude sickness and worked in the field for 48 days.

"The grasses began to thrive, with some varieties growing over 40 centimeters by late August, surpassing our expectations," said Guo, adding that the overwintering process has been progressing well so far.

The planting of space-bred seeds in Xizang has proven to be a roaring success.

Despite encountering extreme, low temperatures of minus 40 degrees Celsius, these plants are capable of surviving the winter, according to Guo.

The team also collected 350 grams of seeds from 11 local crops in Xizang, including barley and rapeseed. These seed packets were launched into space aboard China's first reusable and returnable satellite, Shijian-19, in September, and the retrieved payloads were delivered to scientists in October.

"In the future, we will introduce space-bred vegetable and fruit seeds in Xizang to boost local agriculture," said Guo, his eyes brimming with confidence as he stood on the field's ridge, gazing toward the horizon.