Before people begin to build bases beyond the Earth, scientists will have to solve a number of complex problems and answer many questions. One of these challenges is growing plants in extreme conditions, which are very different from those on Earth. Scientists were especially concerned about low gravity. However, recent research indicates that the problem can be solved – plants grow normally in low gravity conditions, in fact, it helps them withstand other negative environmental conditions, such as extremely low temperatures.
You can actually grow plants on the Moon
Plants have sprouted on the Moon
The Chinese Chang'e-4 lander, which landed on the moon in 2019, carried seeds of four types of plants on board. The scientists' task was to grow them on the Moon. As a result of this experiment, only the cotton seed sprouted successfully. Then this event attracted a lot of attention from scientists around the world. However, just the germination of a seed is not enough to talk about success.
The plant must not only germinate, but grow and be resistant to negative environmental conditions. It is important that the crops bear fruit and be sufficiently productive. Failure to meet any of these requirements can be a serious problem. But, before moving on to full-fledged cultivation, it is necessary to find out how possible this is. Therefore, during the Chang'e-4 mission, scientists were not faced with the task of growing plants in lunar soil in an open area.
Some previous studies have shown that the soil on the Moon is quite suitable for these purposes. Regarding solar radiation, this problem can be solved by providing domes or canopies over the beds. The only potential problem that cannot be solved is gravity. But, as mentioned above, it did not turn out to be an obstacle to growing plants outside the Earth.
Aboard «Chang'e-4» cotton sprouted and survived extreme night temperatures
How low gravity helps plants
Despite the fact that the experience of growing plants on the Moon as part of the Chang'e-4 mission was carried out back in 2019, the study was published relatively recently – in June 2023, and some more detailed information about this experience appeared even later.
In fact, two studies were carried out at once – one on the Moon, and the second on Earth. Scientists created the same conditions for seeds in the laboratory as on board Chang'e-4, that is, they provided the same pressure, temperature and humidity, and also used the same soil in which the seeds were planted on the Moon. The task was to compare how plants develop under the same conditions on Earth and the Moon. The only difference was gravity.
As it turned out, a little gravity significantly accelerated the process of seed germination. True, only cotton seeds sprouted on the Moon, while canola seeds also sprouted on Earth.
Cotton seedlings on Earth did not tolerate low temperatures, unlike the same seedling on the Moon
The biggest problem for the plant on the Moon was the long night that began nine Earth days after landing. At this moment, the temperature inside the compartment dropped to -52°C. Moreover, the heat did not return for 18 Earth days.
It would seem that these are extreme conditions that the plant cannot survive, but by the onset of the new lunar day the seedling remained green and stood upright. On Earth, the seedlings had quite naturally died by this time and were already black and yellow in color.
As a result, the lunar seedling was able to survive the second lunar day. True, his growth has stopped, but scientists attribute this to a lack of oxygen in the compartment. Considering that only gravity differed on Earth and the Moon, we can conclude that it was gravity that helped the plant survive extreme conditions. Scientists report this in their research, which was published in the journal Microgravity Science and Technology and Acta Astronautica.
Some polar plants on Earth can even withstand extremely low temperatures
It must be said that some polar plants have also developed the ability to survive in extreme cold. However, plants from warm climates do not have this ability. Unfortunately, the seedlings died on the second moonlit night. But the result can still be called positive. Most likely, if the conditions were corrected, the cotton would have continued to grow.
The fact that other plant species were unable to germinate is attributed to the unfavorable temperature during the first five days after landing. Therefore, there is hope that lunar agriculture has good prospects.
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Finally, let us remind you that scientists have already grown plants on the ISS, moreover, they even got a harvest. Therefore, in the future, most likely, astronauts will be able to grow plants not only at lunar or Martian bases, but also during long flights.