17:15 〜 18:45
[MIS07-P07] 火星と月を想定した低圧下での樹木育成
キーワード：樹木育成、その場での持続可能な資源、低圧、閉鎖生態系生命維持システム
[Introduction]
When humans inhabit Mars in the near future, trees will play an important role in providing a sustainable wood supply, oxygenation and healing effects for humans on Mars. We are conducting basic research to explore the possibility of growing trees on Mars. There are several studies assuming plant cultivation on extraterrestrial space [1],[2], including Mars. However, these studies are mainly aimed at food production, and there are not many researches about trees [3]. On Mars and the Moon, where the atmospheric pressure is much lower than Earth's, humans will live in domes pressurized to the same atmospheric pressure as Earth. If the air pressure inside the dome used to grow plants can be made lower than that in the residential dome, the cost of constructing and maintaining the dome can be reduced. We investigated the growth characteristics of trees under low pressure using a custom created low pressure tree growth experiment apparatus (LPTGEA), a closed chamber.
[Materials and Methods]
(1) Materials: Seedlings 30 to 40 days after cuttings were used in the study. Seedling are clones.
(2) Experimental conditions: The LPTGEA was placed in a room whose temperature was adjusted to approximately 25℃. The environment inside the LPTGEA during the experiment was controlled by a microcomputer with a carbon dioxide concentration of 500 ppm, a relative humidity of 50%, and an arbitrary atmospheric pressure of 0.75, 0.5, 0.3, 0.2 or 0.1 atm. An LED light was used as the light source, and the seedlings were illuminated from directly above the LPTGEA.
(3) Measurements: height, ground diameter, and dry weight of each part of the seedling before and after measurement. LMA (leaf mass/leaf area). Taking photos of seedlings every 30 minutes.
[Results and discussion]
(1) Tree height analysis: The growth rate of seedlings under 0.1 atm was slower than that under 1 atm, and no significant difference was observed under other atmospheric pressures.
(2) LMA: Under both low and 1 atm, the younger the leaf, the larger the LMA and decreased as the leaves matured. Furthermore, LMA was larger under low pressure than that under 1 atm. The difference in LMA between low and 1 atm pressures decreased as the leaf matured. The leaves at the beginning of development from the bud were relatively thick.
Under low-pressure environment of 0.2 atm or higher, an initial growth of tree was affected by the low pressure, and then over time trees grew to the same level as under normal atmospheric pressure. This is probably because they have adapted to the low-pressure environment.
After this, in order to further understand tree growth under low pressure, we will consider repeating the experiment, extending the growing period, examining the effects of O2 partial pressure, and genetic analysis.
References
[1] Goto,E., Iwabuchi.K, and Takakura.T. (1995) Effect of reduced total air pressure on spinach growth. J.Agri.Meteorol 51: 139-143
[2] Tang,Y., Guo,S., Dong,W., Qin,L., Ai,W. and Lin,S. (2010) Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce. Adv. Space Res. 46: 751-760
[3] Nagatomo, M. (2005) Experimental study on growth of young trees under the pressure of one tenth of earth atmosphere. The Journal of Space Technology and Science 21(2):2_11-2_26.
When humans inhabit Mars in the near future, trees will play an important role in providing a sustainable wood supply, oxygenation and healing effects for humans on Mars. We are conducting basic research to explore the possibility of growing trees on Mars. There are several studies assuming plant cultivation on extraterrestrial space [1],[2], including Mars. However, these studies are mainly aimed at food production, and there are not many researches about trees [3]. On Mars and the Moon, where the atmospheric pressure is much lower than Earth's, humans will live in domes pressurized to the same atmospheric pressure as Earth. If the air pressure inside the dome used to grow plants can be made lower than that in the residential dome, the cost of constructing and maintaining the dome can be reduced. We investigated the growth characteristics of trees under low pressure using a custom created low pressure tree growth experiment apparatus (LPTGEA), a closed chamber.
[Materials and Methods]
(1) Materials: Seedlings 30 to 40 days after cuttings were used in the study. Seedling are clones.
(2) Experimental conditions: The LPTGEA was placed in a room whose temperature was adjusted to approximately 25℃. The environment inside the LPTGEA during the experiment was controlled by a microcomputer with a carbon dioxide concentration of 500 ppm, a relative humidity of 50%, and an arbitrary atmospheric pressure of 0.75, 0.5, 0.3, 0.2 or 0.1 atm. An LED light was used as the light source, and the seedlings were illuminated from directly above the LPTGEA.
(3) Measurements: height, ground diameter, and dry weight of each part of the seedling before and after measurement. LMA (leaf mass/leaf area). Taking photos of seedlings every 30 minutes.
[Results and discussion]
(1) Tree height analysis: The growth rate of seedlings under 0.1 atm was slower than that under 1 atm, and no significant difference was observed under other atmospheric pressures.
(2) LMA: Under both low and 1 atm, the younger the leaf, the larger the LMA and decreased as the leaves matured. Furthermore, LMA was larger under low pressure than that under 1 atm. The difference in LMA between low and 1 atm pressures decreased as the leaf matured. The leaves at the beginning of development from the bud were relatively thick.
Under low-pressure environment of 0.2 atm or higher, an initial growth of tree was affected by the low pressure, and then over time trees grew to the same level as under normal atmospheric pressure. This is probably because they have adapted to the low-pressure environment.
After this, in order to further understand tree growth under low pressure, we will consider repeating the experiment, extending the growing period, examining the effects of O2 partial pressure, and genetic analysis.
References
[1] Goto,E., Iwabuchi.K, and Takakura.T. (1995) Effect of reduced total air pressure on spinach growth. J.Agri.Meteorol 51: 139-143
[2] Tang,Y., Guo,S., Dong,W., Qin,L., Ai,W. and Lin,S. (2010) Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce. Adv. Space Res. 46: 751-760
[3] Nagatomo, M. (2005) Experimental study on growth of young trees under the pressure of one tenth of earth atmosphere. The Journal of Space Technology and Science 21(2):2_11-2_26.