Speed ​​Appropriateness of Clinostat

[Jiny]

In an experiment to grow plants in microgravity using an Arduino clinostat, I implemented normal gravity and microgravity conditions and conducted an experiment with red radish seeds. When implementing microgravity conditions, a clinostat with 30 RPM was used. My prediction was, ‘In microgravity, plants will grow in random directions.’ However, as a result of the experiment, it grew in a certain direction, although the direction was clearly different from that under gravity, as shown in the picture below. So I'm not sure if I've implemented microgravity correctly. Therefore, what I want to ask is whether microgravity can be achieved at a speed of 30 RPM and whether this experiment went well.

[Jiny]

Oh, sorry. The two photo captions were swapped.

[Jiny]

1. Does the microgravity effect appear at 30 RPM of the Clinostat? 2. The speed of the clinostat was so fast that I wonder if it was affected by centrifugal force. So, I wonder whether the bending of plant stems and roots is due to centrifugal force or waving and skewing. 3. Can waving and skewing also occur in the ‘stem’ of a plant?

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[bfinio]

Hi,

While the project recommends 10-15RPM, even at 30RPM, the centripetal acceleration is still very low. I won't post the details here, but I did the calculation for a seed at a radius of 2cm from the center of the dish, and got a value of about 0.2 meters per second squared, which is less than 2% of Earth's gravity.

If you WERE seeing centripetal effects because the dish was spinning too fast, then I would expect to see all the roots growing radially outward from the center, but that does not appear to be the case. It looks like your plants all still grew in the same direction. If you did this experiment in a classroom, is there any chance that power was interrupted to the Arduino overnight, causing it to stop spinning?

[amyCC]

Administrator note: Previous post related to this project: viewtopic.php?p=75981#p75981

[Jiny]

Hi,

While the project recommends 10-15RPM, even at 30RPM, the centripetal acceleration is still very low. I won't post the details here, but I did the calculation for a seed at a radius of 2cm from the center of the dish, and got a value of about 0.2 meters per second squared, which is less than 2% of Earth's gravity.

If you WERE seeing centripetal effects because the dish was spinning too fast, then I would expect to see all the roots growing radially outward from the center, but that does not appear to be the case. It looks like your plants all still grew in the same direction. If you did this experiment in a classroom, is there any chance that power was interrupted to the Arduino overnight, causing it to stop spinning?

Maybe it didn't stop. When I went the next day, the servo motor was still running.

[bfinio]

Do you have any more pictures you can upload of the petri dishes without the lid? It's hard for us to see what's going on with all the condensation on the lid.