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Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressureThe response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.
Document ID
20040087842
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Spanarkel, Robert
(College Station TX 77843-2133, United States)
Drew, Malcolm C.
Date Acquired
August 21, 2013
Publication Date
December 1, 2002
Publication Information
Publication: Physiologia plantarum
Volume: 116
Issue: 4
ISSN: 0031-9317
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG9-669
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Life Support Systems
Non-NASA Center

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