ADVANCED PLANT EXPERIMENTS - CAMBIUM (APEX-CAMBIUM)
Research Area Plant Biology
Expeditions 20- 21
Principal investigator(s): ● Rodney Savidge, PhD, University of New Brunswick,
Fredericton, New Brunswick, Canada
RESEARCH OBJECTIVES
Astronauts on the International Space
Station engage in the unusual task of
bending weeping willow (Salix babylonica)
stems into loops to determine the role
gravity plays in forming different kinds of
wood.
Parts of a tree that are not vertical typically
grow one kind of wood on one side and
another kind on the other. This is known as
“reaction wood,” and the mix of different
kinds of this wood in trees influences their
suitability for different uses, such as
construction or paper. Scientists believe
reaction wood is a response to gravity, but
they haven’t been able to prove it. APEX-
Cambium determines if reaction wood forms to the same extent, and in the same position as in
trees grown on Earth.
EARTH BENEFITS
Understanding the fundamental processes by which plants produce cellulose and lignin in their
tissues is of great interest in the realm of forestry and industry. Trees used for paper production
are selected for maximum cellulose production and minimal lignin production. Conversely,
trees used to make structural lumber are selected for maximum lignin content. However, due
to the complex relationship of these 2 biosynthesis processes, researchers do not yet know how
to genetically alter such plants to further boost their productivity. Gravity is suspected to
strongly affect the formation of reaction wood, and this experiment determines if this is true.
SPACE BENEFITS
APEX-Cambium along with the Advanced Biological Research System hardware demonstrates
the capabilities of providing the correct environment for plant growth aboard spacecraft. For
future long-duration exploration, crews will need to be able to grow plants for a variety of
applications.
RESULTS
Data analysis for this investigation is ongoing; no results have been published to date.
This investigation is complete; however additional results are pending publication.
Canadian Space Agency astronaut and Expedition 20/21
crew member Bob Thirsk poses with the Canadian willow
trees used for the Advanced Plant Experiments -
Cambium experiment. NASA image.