China's historic 23-day Chang'e 5 mission has not only obtained precious rocks and soil samples from the moon, but has also brought back a group of seeds that traveled the furthest in the nation's agricultural and forestry histories.
More than 30 kinds of seeds, including rice, oats, alfalfa and orchid, were placed inside the multi-module Chang'e 5 spacecraft and orbited around the moon for about 15 days.
Scientists wished to check what would happen to the seeds after being exposed to a unique environment in lunar orbit and also hoped that they could develop beneficial mutations.
The seeds were chosen by multiple domestic organizations such as China Agricultural University, Beijing Forestry University, South China Agricultural University and the Chinese Academy of Agricultural Sciences in a space-based mutation breeding program arranged by the Beijing-based China High-Tech Industrialization Association.
They were handed over to the participating organizations at a ceremony at the China National Space Administration on Dec 23.
Liu Jizhong, director of the administration's Lunar Exploration and Space Program Center, said that the program was the first time Chinese researchers conducted mutation breeding experiments in deep space and it offered good opportunities to scientists.
Professor Sun Yeqing from Dalian Maritime University in Liaoning province, who had her rice and Arabidopsis thaliana seeds onboard Chang'e 5, said that the mission gave a valuable opportunity for researchers to expose their seeds to a deep-space environment, and would enable them to deepen their studies on the effect of cosmic rays on the growth and evolution of life on Earth.
Space-based mutation breeding refers to the process of exposing seeds to forces such as microgravity, vacuums and cosmic radiation during a spaceflight and then sending them back to Earth for further observation and planting.
Researchers observe and examine several generations of plants grown from space-bred seeds and investigate their mutations — some are positive and desirable while others are negative. Those with positive mutations will be kept and analyzed, and will be introduced to farmers after their certification and approval.
Space breeding can generate mutations faster and more conveniently than ground-based experiments and can bring about some desirable traits that are otherwise hard to introduce.
Compared with natural or conventionally bred types of plants, space-developed versions with positive mutations usually feature higher nutritional content, greater annual yields, shorter growth periods and better resistance to diseases and insect pests, researchers explained.
China conducted its first space breeding experiment in 1987, using a satellite to carry seeds into space.
Since then, hundreds of kinds of seeds and seedlings have traveled with dozens of Chinese spaceships, including the Shenzhou manned spacecraft and recoverable satellites.
Space breeding has helped to produce more than 200 new types of mutated plants in China that have been approved for large-scale cultivation, ranging from grains to vegetables and fruits, said Liang Xiaohong, executive vice-chairman of the China High-Tech Industrialization Association.
The Chang'e 5 robotic mission was launched by a Long March 5 heavy-lift carrier rocket early on Nov 24 in Hainan province. The mission returned 1,731 grams of lunar rock and soil to Earth, marking a historic accomplishment 44 years after the last lunar substances were retrieved.
