Heat and gas exchanges between plants and atmosphere under microgravity conditions

Yoshiaki Kitaya, Masayuki Kawai, Hideyuki Takahashi, Akira Tani, Eiji Goto, Takahiro Saito, Toshio Shibuya, Makoto Kiyota

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Citations (Scopus)

Abstract

Fundamental studies were conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long term under microgravity conditions in space. To clarify the effects of gravity on heat and gas exchanges between plant leaves and the ambient air, surface temperatures and net photosynthetic rates of barley leaves were evaluated at gravity levels of 0.01, 1.0, and 2.0 g for 20 sec each during parabolic airplane flights. Thermal images were captured using infrared thermography at an air temperature of 22°C, a relative humidity of 18%, and an irradiance of 260 W/m2. The net photosynthetic rates were determined by means of a chamber method with an infrared gas analyzer at an air temperature of 20°C, a relative humidity of 50%, and photosynthetic photon fluxes (PPFDs) of 250 and 500 μmol/m 2/sec. Mean leaf temperatures increased by 1.9°C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.6°C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was greater at the regions closer to the leaf tip and at most 2.5°C over 20 sec as gravity decreased from 1.0 to 0.01 g. The net photosynthetic rate decreased by 20% with decreasing gravity levels from 1.0 to 0.01 g and increased by 10% with increasing gravity levels from 1.0 to 2.0 g at a PPFD of 500 μmol/m 2/sec. The heat and gas exchanges between leaves and the ambient air were suppressed more at the lower gravity levels. The retardation would be caused by heat and gas transfers with less heat convection. Restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air.

Original languageEnglish
Title of host publicationInterdisciplinary Transport Phenomena in the Space Sciences
PublisherBlackwell Publishing Inc.
Pages244-255
Number of pages12
ISBN (Print)1573316393, 9781573316392
DOIs
Publication statusPublished - 2006 Sep

Publication series

NameAnnals of the New York Academy of Sciences
Volume1077
ISSN (Print)0077-8923
ISSN (Electronic)1749-6632

Keywords

  • Barley
  • Heat convection
  • Infrared thermography
  • Leaf temperature
  • Microgravity
  • Parabolic airplane flight
  • Photosynthesis
  • Space

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • History and Philosophy of Science

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