Skip to page content Mission Information


Plant Growth/Plant Phototropism (ED61_62)
Principal Investigator
Research Area:
Plant biology
Species Studied
Scientific Name: Oryza sativa Species: Rice


Phototropism is the characteristic exhibited by plants as they grow towards the main source of light. Plant leaves near a window will orient themselves toward the Sun. Geotropism is a plants reaction to the force of gravity. Plant roots react positively to geotropism and grow down, while the stem exhibits a negative response to gravity and grows upward in the opposite direction.

This experiment was a combined study that converged from two similar proposals. The first proposal suggested the study of microgravity effects on the orientation of roots and stems of germinating seedlings. The second proposal suggested an experiment to determine the phototropic response under various light intensities to determine the illumination level required to produce the phototropic response. The combined objectives of this experiment were (1) to observe and record the differences in root and stem growth and orientation of rice seeds germinated in the Skylab environment and (2) to assess whether phototropism can serve as a geotropism substitute for rice seeds germinated and developed in the Skylab environment.

The germination and growth of seedlings in microgravity raised secondary questions concerning the role of gravitational forces on seedling development. New plant life begins when a sperm nucleus from a pollen grain unites with an egg nucleus and the resulting cell begins developing a seed. The seed develops into an embryo-like stage and begins to grow or germinate after it is exposed to water. This experiment addressed a fundamental question of how microgravity affects the process of germination.

++ -- View more

Anonymous. MSFC Skylab student project report. NASA Marshall Space Flight Center; Huntsville, AL, United States. August 01, 1974. NASA-TM-X-64866. [NTRS]

Newkirk RW, Ertel ID, and Brooks CG. Skylab: A Chronology. January 01, 1977. NASA SP-4011. [NTRS]

Skylab Student Project Summary Description. Huntsville, AL: NASA George C. Marshall Space flight Center; 1973. MSFC SL-73-3.

Summerlin LB, ed. Skylab, Classroom in Space. NASA Marshall Space Flight Center; Huntsville, AL, United States. January 01, 1977. NASA SP-401. [NTRS]


Photo Gallery
+ View digital images

Data Information
Data Availability
Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Plant growth

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Skylab 3 07/28/1973 09/25/1973 59.5 days

Additional Information
Managing NASA Center
Marshall Space Flight Center (MSFC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Protocol / Approach
Not applicable
Hardware Items