In recent years, the development trend of the space industry of the world's space powers is to compete for civilian launches, and the international community has carried out more extensive cooperation in the space field. In the past, the spacecraft of the United States and the former Soviet Union kept secrets from each other, but today, the United States and Russia have become "partners". Scientists in the United States and Russia have considered taking joint action for the exploration of Mars. It has repeatedly claimed that space activities will be tilted towards the civilian sector and will focus on projects with short development cycle, low cost, low risk and good benefits. For example, making satellites and using space shuttles to transport animals and plants to users.

At present, the United States is vigorously carrying out research on space plants. After the Kennedy Space Research Center was established in Florida, the Gravity Biology Center was recently established at the University of North Carolina. Scientists will begin to study plants suitable for space travel. In the long-distance space travel, people should not only adapt to the state of zero gravity, but also adapt to plants that provide food and oxygen for people. Their research focuses on how calcium affects the ability of plants to respond to gravity. Calcium seems to be the most important chemical element in plants' response to the environment. Researchers will use genetic technology to change the control ability of plants, so as to eventually cultivate plants more suitable for space travel. One experiment of Kennedy Space Research Center is to let a chemist live with 30,000 wheat plants 15 days. The experimental results show that these wheat provide people with the oxygen they need to sustain their lives.

At present, in their 2 1 century space plans, the United States, Japan and western Europe focus on the growth and function of plants in sealed space capsules, and set about building space farms. The United States spends a lot of money on experimental research on space plants, with the aim of promoting and fully proving that spacecraft will eventually become a "flying farm."

Scientists at home and abroad make full use of natural radiation in space, especially the synergistic effect of high-energy particles and microgravity on plant cell function, to induce physiological and biochemical changes and genetic variation of cells, so as to cultivate new plant varieties. Experiments show that space flight can improve the chromosome aberration rate of many plant cells, and excellent new varieties can be selected through space mutation treatment.

Space breeding began in 1984. The Education Department of NASA, the Solar Radiation Research Center and Parker Seed Company cooperated to transport a large number of tomato seeds to a long-term space vehicle, which was recovered by the space shuttle Columbia in 1990. The results showed that these seeds germinated quickly, the seedlings grew normally, developed well in the later stage and had rich fruits. It is reported that the fourth generation "space wheat" harvested by Shanghai Institute of Plant Physiology of China Academy of Sciences 1995, like other excellent varieties, has golden ears and full grains. Compared with the third generation "space wheat", it grows more vigorously, with long ears, more ears, big and strong seeds and strong resistance to scab. It is estimated that the yield per mu can reach 352kg, 28kg more than that without space flight, and the protein content is 9% higher. Experts from Zhejiang Academy of Agricultural Sciences have cultivated a new rice variety "Yuhang 1" for three years. The theoretical yield per plant increased from 22.4 grams to 32.8 grams, and the yield per mu increased from 400 kilograms to about 600 kilograms, with an increase rate of more than 40%. But also lodging resistance, early maturity and high yield, large panicle and many grains, high milled rice rate and good palatability. The growth period of the new variety is shortened by about 15 days, and the plant height is reduced by about 14 cm, which has the advantages of resistance to rice blast and bacterial blight.

Using the unique conditions of space to improve plant varieties has broad prospects, which opens up a new way to speed up the cultivation of high-quality and high-yield crop varieties and also puts forward a new topic for scientists to study in depth.

Space experiments at home and abroad have proved that for space agriculture, unlike soilless culture on the earth, plants cannot absorb water or nutrients in the form of water droplets. In the case of weightlessness or only a little centrifugal simulation of gravity, in order to prevent the loss of liquid, water must be in the form of water film to be absorbed by plants.

Under the unique conditions of space, which plants should be screened as its "darling"? At present, scientists in the United States and Japan are jointly tackling key problems, and plan to plant sweet potatoes in the spacecraft as future space crops for astronauts to eat. Sweet potato is so lucky because it is rich in nutrients and contains many nutrients needed by human body. According to the measurement, every 500 grams of sweet potato produces about 635 kilocalories, including protein 1/kloc-0.5 grams, sugar 14.5 grams, fat1gram, phosphorus 100 mg, calcium 90 mg, iron 2 mg and carotene 0. It has high medicinal value and is beneficial to prevent constipation and rectal diseases. It also contains substances similar to estrogen, which is very beneficial for protecting skin, delaying aging, improving immunity, promoting cholesterol excretion and maintaining arterial elasticity. Recently, American biologists found that a chemical rich in sweet potato can be used to prevent colon cancer and breast cancer. The Japanese Institute for Cancer Prevention investigated the relationship between the diet of 260,000 people and cancer, and found that the inhibition rates of cooked sweet potato and raw sweet potato on cancer were 98.7% and 94.4% respectively, which were the highest among vegetables and exceeded the anticancer effect of ginseng. In addition, sweet potato has strong adaptability, easy to grow and live, and high yield. It only needs a short vine stem, a small piece or even a radish leaf to take root and survive. Planting in the spacecraft can not only supplement the oxygen in the cabin, but also form a small ecological cycle closed environment, and can also be used as fresh food for astronauts.

At present, NASA scientists are experimenting with potato growth in a closed environment in a special laboratory at the Kennedy Space Research Center in Florida. The results showed that the potato plants in this experiment produced enough oxygen for an astronaut. Like sweet potatoes, potatoes can provide food and energy for astronauts. Scientists also collected "pure water" from potato leaves. It can be used as drinking water for four people.

Scientists expect that the research on the basic life support system of human beings by plants will make it a reality for human beings to land on Mars. The trip to Mars is expected to take three years of long-distance flight, but as long as the planting area is enough and crops such as sweet potatoes and potatoes are planted, astronauts can survive for a long time without hunger and thirst during the flight.