Effects of Hypobaric Environment on Growth and Physiological Characteristic of Lettuce

TANG Yong-kang; GUO Shuang-sheng; QIN Li-feng; AI Wei-dang

Abstract：Objective To investigate the characteristic of growth and development of vegetable at hypobaric environment and offer the cultivating technique of controlled ecological life support system for higher plant. Methods The means of comparative measurement was adopted to study the growth and physiological characteristic of lettuce under low and normal pressure (40. 0 kPa, 101. 0 kPa), which was carried out with the low pressure plant-cultivating facility. Results Compared with normal pressure, germination rate of lettuce seed was eliminated by 7.62% under total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa conditions; harvest time of lettuce was delayed, so biomass harvested at the same time reduced by 13.67% and content of total saccharide declined; the average rates of photosynthesis and transpiration were lower than those at normal pressure in 30 days after planting (DAP) , but which reversed after that; release of C2H4 and shoot height reduced by 38.79% and 11.68% , but leaf area, ratio of root to total biomass and root vigor increased by 15.43% , 2.57% and 40. 53% , respectively. Conclusion Seed germination, growth and development of lettuce are affected in some degree at total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa, some measures should be adopted to regulate the growth of lettuce.