BEIJING -- The Chinese spacecraft Shenzhou 8 launched earlier this month with some unusual cargo on board: hundreds of carefully vacuum-packed walnut and date seeds.
The seeds were selected as part of a Chinese government program which has put thousands of seeds into orbit over the past few years. Researchers say that space travel can change the genetic makeup of plant seeds, producing super-yielding plant varieties when they are eventually planted back on planet earth. Space seeds have produced new kinds of rice, wheat and vegetables which are more productive, larger, and more nutritious than their earthly counterparts, according to Chinese reports.
Chinese research into “Space breeding,” as the practice is known in China, began in the 1980s, when the first batch of Chinese seeds entered orbit attached to a satellite, returning to earth five days later. Satellites continued to carry Chinese seeds into space through the 1990s, but the pace of the program has accelerated rapidly in recent years. “In the past five years the government doubled its investment in the program,” Professor Liu Luxiang, director of the Space Breeding Research Center at the Chinese Academy of Agricultural Sciences said. “That helped us increase the number of new seed varieties produced by Space breeding from just 20 to 110.”
The first improved variety of plant to be grown from a space seed was a strain of rice known as Huahang 1, yields of which were reported to have improved by more 4%. But Liu is proudest of the new varieties of wheat produced by the breeding program, some of which are now being grown commercially in China. One
variety, named Taikong 6, is “more nutritious,” than normal varieties, because it contains elevated levels of protein. “Its great for baking,” Liu said.
A recent paper published in the journal Space Policy touted other space seed successes, including a kind of soybean with 11% higher yields than usual, supersized green peppers weighing in at 500g, as well as oversized cucumbers and tomatoes with unusually high sugar content, whose taste is “comparable to oranges,” according to the report.
But ever the sober-minded scientist, Professor Liu is frustrated by the media’s constant obsession with gigantic pumpkins and oversized peppers. “Size isn’t the point of the program,” he said. “I care more about increasing yields,” he said.
Levels of radiation
Precisely how a brief sojurn in space can alter the size or fertility of plants is still a mystery to Chinese scientists. “We are still investigating exactly what the mechanism is,” Liu said. The most popular explanation
is that the seeds are exposed to higher levels of radiation than on earth, and some scientists propose that lower levels of gravity also play a role.
Other experts doubt that that either radiation or lower gravity could change the genetic makeup dried seeds in this way. “Dehydrated seeds are very inert,” Dr. Cary Mitchell, professor of horticulture and plant physiology at Purdue University said. “I’m very sceptical that they’d respond to radiation in any way.”
Those doubts are compounded by uninspiring results from a previous space seed experiment carried out in the USA. As part of the Challenger space shuttle program, more than twelve million Rutgers California Supreme tomato seeds were put into orbit, where they remained for nearly five years. After they were returned from space by the Colombia space shuttle, the seeds were distributed to middle school children across the United States, who were grew the seeds alongside others from a control sample, which had been kept on earth.
In China’s space breeding experiments, seeds are exposed space conditions for about six days on average. But although the American tomato seeds experienced the same conditions for a vastly longer period of time, experimenters concluded that, fruit yield was “unaffected” in plants grown from space-exposed seeds.
Still very secretive
A lack of publications in credible scientific journals has prevented Chinese space breeding researchers from winning the recognition of the international scientific community. “[The Chinese] publications read more like technical reports than scientific papers,” one American botanist, who asked not to be named, said. “The Chinese are still very secretive about any space-related research, because of its connections to the military,” the botanist said. Secrecy surrounding the project means that Chinese reports often lack key information on the methods and materials used in space-experiments.
That’s something Liu hopes to change in the coming years “I admit the lack of publications has been a problem,” he said. “But we have at least two publications under review by high-ranking journals.”
The seeds carried by the Shenzhou 8 were not selected by Professor Liu’s research team, but by a competing research team based in Central China’s Henan province. A rush by local governments and private businesses to grab a slice of the lucrative space breeding industry has led to a rapid rise in the number of space breeding “research bases,” of which China now has nearly 60. “Some companies are using the name of space breeding to promote seeds which have no connection with space,” Liu said.
Liu is confident that the space breeding program will continue to make breakthroughs. “We’re very happy with the level of government support, which will continue over the next five years,” he said. But he is realistic about the downsides of space breeding. “Compared with conventional methods of breeding seeds, the costs are much higher,” he said, estimating that at least $500 USD is spent for each seed launched into space. Over 90 percent of seeds are completely uneffected by space flight, Liu said. “That’s why space breeding should be used in combination with traditional seed breeding, and shouldn’t replace other methods of altering seeds, such as by exposure to nuclear radiation."