What aspects of research have scientists conducted on space agriculture?

In order to provide people living in space orbit for a long time with all kinds of delicious foods similar to those on the earth and solve the food supply of more space immigrants in the future, people put forward the idea of establishing a closed space ecological environment and agricultural base in space? As early as more than 20 years ago, NASA began to study space crop cultivation and closed ecology?

In recent years, it is more concrete and fruitful for the United States to engage in such research with the help of the space shuttle? In order to study the germination rate of seeds under weightlessness in space? Dormancy? In terms of vitality and gene mutation, the United States used to put plant seeds involved in experiments in special tanks in the payload cabin of spacecraft in different ways? Some seeds are sealed in special pots to avoid some harsh space environment; Some seeds are open, completely exposed to the space environment and in a state of weightlessness? Vacuum? Extreme temperature changes and the test of cosmic ray radiation, and then these seeds after space travel are planted on the ground of greenhouse for comparative experiments to observe what obvious reactions plants have to weightless environment, and how weightless environment affects the growth of plants. Development? Maturity and decay, for which people have done many interesting experiments? 1On April 4th, 983, during the first flight of the American space shuttle Challenger, 1 1.3kg of vegetables were used. Herbs and flowers are planted in space orbit? This batch of seeds has 46 varieties; Among them are African purple chicory moss? Spinach in Melody and spinless okra in clemson? Tomatoes? Beans Sweet corn? Cucumber? Lai Sesame or something? 1On April 7th, 984, the American space shuttle Challenger put an experimental device containing about14 million plant seeds into space orbit on its fifth flight, and it was planned to be brought back to the ground by another space shuttle in early February ten months after the flight? The purpose of the experiment is to see what kind of packaging can be unaffected by the cosmic environment.

The ultimate goal of plant seed space experiment is to open up an oasis in space? Because in the space shuttle, astronauts and their crew need oxygen? At present, water and food have to be brought from the ground, which is neither economical nor reliable, and it is difficult to meet the needs of long-term manned space flight? In order to solve this problem, tsiolkovsky, a scientist of the former Soviet Union, once suggested that advanced plants must be used as a means for people to maintain their lives in long-term space flight? According to this theory, Korolev proposed to build a greenhouse with a closed ecological circulation system and select some plants whose metabolic functions are related to human beings? Animals and microorganisms? Regenerated oxygen? Water and food provide two ecological environments similar to the earth's environment, which provide life support for astronauts' long-term space life and provide an ecological environment similar to the earth for the establishment of scientific experimental stations and space cities on other planets in the future? Therefore, in the early days of space flight, the former Soviet Union launched the second spacecraft in 1960, and studied Chlorella? Purple Commelina and all kinds of onions? Peas? Wheat and corn seeds are tested? Later, Chlorella was sent to the "Oriental V" manned spacecraft for space travel. 197 1 The former Soviet Union experimented with tulips on the Soyuz-10 spacecraft and found that they miraculously blossomed after returning to the ground? 1989, the former Soviet Union set up a special greenhouse in Salute -6 space station to cultivate wheat? Peas? Onions? Tulips, orchids and other plants, in which tulips not only grow new leaves? Living roots were born, and the success of these experiments undoubtedly brought gratifying information to space oasis developers?

Lignin is a substance that binds plant fibers together and makes plants stand upright? Astronauts were worried that the growth of lignin would be hindered under weightlessness? In order to solve this mystery,1in March, 983, when the space shuttle Columbia was flying, mung beans were released. Oats? Pine tree? Seeds of 96 kinds of plants, such as cucumbers and peas, were sent into space to sprout and grow leaves in special plants in the cargo hold? Experiments show that the roots of oats and mung beans can stick out of the soil instead of growing downward in the normal way? The roots of pine trees grow into the soil as usual? On the contrary, the protein ratio of pine trees usually increases by 20%~30%? 1982, the former Soviet Union planted Arabic grass in Salute -7 space station. This plant grew slowly in space for about 30 days, and didn't blossom until August 2, then planted 27 flower pods on the straw and harvested more than 200 seeds? These experiments deny the idea that weightlessness affects the growth of plant lignin? Played an important role in the birth of cosmology?

The plants in the space oasis are different from the plants on the earth because of the change of environmental conditions? Because of the gravity of the earth, plants on the earth have gradually formed functions suitable for bearing gravity, such as geotropism. Phototropism top advantage, etc? However, when the plants in the universe grow in an environment without gravity or microgravity, the situation will change. For example, China mung bean was taken into space by the space shuttle for experiments. As a result, mung bean sprouts twisted in several directions, and the growth direction was very chaotic, instead of growing in the direction of light. More than 50% of the roots of mung bean sprouts come from the soil, not rooted in the soil? Secondly, the cells and biochemical components of plants in the universe may also change. For example, the former Soviet Union used electric stimulation in spacecraft to force onions to grow green leaves. When astronauts tasted onions in space, they found that the taste of onions was bitter?

Space travel and the planting of plant seeds announced the birth of cosmology? Confirmed the technical feasibility of human beings opening up space oases? But there are still many difficulties and problems in practice that need to be explored for a long time?

In order to cultivate fruit trees and vegetables in space, even grow wheat, and provide sufficient living materials for long-term manned space flight and interplanetary navigation, a concept of space agriculture is being conceived and studied?

Researchers from the U.S. Department of Agriculture are working with NASA to determine the problems that must be solved to realize agricultural cultivation in space?

Steven Braise, a plant physiologist at the Agricultural Research Center in Bethsville, Maryland, thinks that what kind of growth conditions and light types should be considered in any sealed environment? Root space? Growth medium? Adaptability of soil or nutrient solution and crops to these conditions?

They regard space as an infinitely closed space. Taking light as an example, what will happen to the growth mode of plants supplied in the space station? Under normal circumstances, long nights are conducive to the growth of plant roots, and plants store more photosynthetic products as starch. Therefore, it is assumed that plants can be guided to grow as many roots, stems, leaves and fruits as people want through the cycle of alternating day and night, which is different from the natural cycle.

In order to obtain the basic characteristics of plants' response to light, Brez began to observe the effects of blue light with different brightness on soybean growth under the condition of constant total light intensity? In the experiment; Soybean seeds are planted in a plant growth box, and part of them are irradiated by fluorescent lamps to simulate natural light; The other part is irradiated by low sodium lamp, which does not contain blue light, which is equivalent to the characteristics of shading time? After 86 days, 65438 06% of soybean dry matter irradiated by fluorescent lamp was in the root. And soybean roots without blue light have 8% dry matter? Plants seem to respond more to changes in light quality than to nutrients and water? Generally speaking, people want to have fewer roots and more stems to increase production, but carrots should be another matter?

In a closed space environment, the growth can be influenced by changing the light; It is impossible to change the lighting conditions in the fields on the earth, but people can indirectly change the light shining on plants because plants grow taller and form a shade, and there is less blue light under the shade? When necessary, people can increase or decrease shading by changing sowing amount, changing ridge width or intercropping and interplanting?

In another experiment, they used the microporous tube system designed by NASA for wheat cultivation to study the individual and simultaneous effects of root restriction and root water on plant growth. This study proves that crops such as wheat can be sown in nutrient solution? Growth and harvest, even if the root system is extremely limited?

For space agriculture, unlike soilless culture on earth, plants can't absorb water and nutrients in the form of water drops? In the case of weightlessness or only a little centrifugal simulation of gravity, in order to prevent liquid loss, water must be absorbed by plants in the form of water film? By increasing the suction inside the tube relative to the water or nutrients absorbed through the membrane, researchers can make plants grow in an environment with sufficient nutrient supply and measurable water shortage? This study will eventually help to understand the physiological response of plants to drought and cultivate the drought resistance characteristics of plants?

In short, one day, people will not eat frozen food in space?