Document Detail


Separating the effects of hypobaria and hypoxia on lettuce: growth and gas exchange.
MedLine Citation:
PMID:  18251894     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The objectives of this research were to determine the influence of hypobaria (reduced atmospheric pressure) and reduced partial pressure of oxygen (pO2) [hypoxia] on carbon dioxide (CO2) assimilation (C(A)), dark-period respiration (DPR) and growth of lettuce (Lactuca sativa L. cv. Buttercrunch). Lettuce plants were grown under variable total gas pressures [25 and 101 kPa (ambient)] at 6, 12 or 21 kPa pO2)(approximately the partial pressure in air at normal pressure). Growth of lettuce was comparable between ambient and low total pressure but lower at 6 kPa pO2 (hypoxic) than at 12 or 21 kPa pO2. The specific leaf area of 6 kPa pO2 plants was lower, indicating thicker leaves associated with hypoxia. Roots were most sensitive to hypoxia, with a 50-70% growth reduction. Leaf chlorophyll levels were greater at low than at ambient pressure. Hypobaria and hypoxia did not affect plant water relations. While hypobaria did not adversely affect plant growth or C(A), hypoxia did. There was comparable C(A) and a lower DPR in low than in ambient total pressure plants under non-limiting CO2 levels (100 Pa pCO2, nearly three-fold that in normal air). The C(A)/DPR ratio was higher at low than at ambient total pressure, particularly at 6 kPa pO2- indicating a greater efficiency of C(A)/DPR in low-pressure plants. There was generally no significant interaction between hypoxia and hypobaria. We conclude that lettuce can be grown under subambient pressure ( congruent with25% of normal earth ambient total pressure) without adverse effects on plant growth or gas exchange. Furthermore, hypobaric plants were more resistant to hypoxic conditions that reduced gas exchange and plant growth.
Authors:
Chuanjiu He; Fred T Davies; Ronald E Lacey
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Physiologia plantarum     Volume:  131     ISSN:  1399-3054     ISO Abbreviation:  Physiol Plant     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2008-02-06     Completed Date:  2008-02-26     Revised Date:  2008-03-10    
Medline Journal Info:
Nlm Unique ID:  1256322     Medline TA:  Physiol Plant     Country:  Denmark    
Other Details:
Languages:  eng     Pagination:  226-40     Citation Subset:  IM    
Affiliation:
Department of Horticultural Sciences and Interdisciplinary Program of Molecular and Environmental Plant Sciences (MEPS), Texas A&M University, College Station, TX 77843-2133, USA.
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MeSH Terms
Descriptor/Qualifier:
Atmospheric Pressure
Carbon Dioxide / metabolism
Cell Respiration / physiology*
Chlorophyll / metabolism
Lettuce / growth & development*,  metabolism*
Oxygen / metabolism
Partial Pressure
Plant Leaves / growth & development,  metabolism
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 1406-65-1/Chlorophyll; 7782-44-7/Oxygen

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