To investigate the possibility of plants cultivation at hypobaria and hypoxia , the gas ex-change, ultrastructure and stress resistance of lettuce were conducted under short-term hypobaric and hy-poxic conditions.The gas exchange and growth of 25-day old lettuce (Lactuca sativa L.var.Rome) seed-lings were tested after 1-h or 24-h equilibration under two levels of total atmospheric pressure (101kPa and 30kPa)and three levels of oxygen partial pressure (21 kPa, 6 kPa and 2 kPa).The results showed that the biomass, ratio of root/shoot, water content and mineral contents of lettuce plants were not affect-ed by the changes of total atmospheric pressure and oxygen partial pressure;Under the same total pres-sure conditions (101 kPa or 30 kPa), hypoxia (6 kPa or 2 kPa) resulted in the increases of photosynthe-sis rate , soluble sugar and malondialdehyde and the reduction of dark respiration of lettuce leaves .The change of mitochondrion ultrastructure and the decrease of transpiration were found at 2 kPa oxygen par-tial pressure;Under the same oxygen partial pressure conditions , photosynthesis rate ,the chloroplast ul-trastructure ,the contents of chlorophyll and carotenoid of lettuce leaves were not affected by short-term hypobaric treatment (30 kPa) ,but the rates of dark respiration and transpiration increased and the con-tents of soluble sugar and malondialdehyde in lettuce leaves decreased .Lettuce can grow under short-term hypobaric and hypoxic conditions.Short-term hypoxia (6 kPa or 2 kPa) resulted in hypoxic stress and hypobaria(30 kPa) enhanced the stress resistance of lettuce .%为探索低压低氧环境中培养植物的可行性，研究了短期低压和低氧对莴苣气体交换、叶片超微结构和抗逆特性的影响。将莴苣植株（25天株龄）在两种总压（101 kPa和30 kPa ）和三种氧分压（21 kPa、6 kPa和2 kPa）条件下进行了1小时和24小时平衡处理。发现短期低压和低氧均未影响莴苣植株生物量、根冠比、含水量和大部分矿质养分含量；短期低氧（6 kPa或2 kPa）提高莴苣叶片光合速率，增加可溶性糖和丙二醛的含量，但降低暗呼吸速率，并且2 kPa氧分压导致线粒体变形和蒸腾速率下降；短期低压处理（30 kPa ）增加暗呼吸速率和蒸腾速率，减少可溶性糖和丙二醛的含量。研究表明，莴苣可以在短期低压低氧环境中生长，但短期低氧（6 kPa或2 kPa）造成莴苣逆境胁迫，而低压（30 kPa）能够提高其抗逆性。
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