A centrifugal phytotron was designed and fabricated to study the effects of gravity on the growth of plant. The magnitude of centrifugal force can be selected arbitrarily up to 4G by controlling angular velocity of cultivation drum (1 m diameter). Environmental factors in this phytotron such as temperature, humidity, CO2 concentration and light intensity can also be conditioned.
On the earth, different magnitude and different direction of artificial gravity, which is centrifugal force plus 1G earth gravity, distribute over the cultivation drum. Results of spectral analysis on vibration of the cultivation drum showed that overall vibration changed with centrifugal force and ranged from 0.7 to 2.1G.
Wind velocity over the cultivation drum increased with raising centrifugal force and ranged from 1.5 to 2.7 m s-1.
Results of preliminary cultivation experiment with radish (Raphanus sativus L.) showed that mean dry weight of the plants cultivated under centrifugal force of 2G was not significantly different from that of the plants cultivated under centrifugal force of 1G, and root/total dry weight ratio increased with raising centrifugal force. These tendency, however, might be due to several physical factors described above.
Isolation of gravitational effect on the plant growth from existing influential factors such as the vibration and wind will be required for further experiment.
