|MadSci Network: Botany|
Magnetism does affect some organisms, but I do not believe that it was the cause of the differences in this situation. I have never read about plant growth being altered by magnetism. I have a few ideas as to what might have happened.
First, the magnets could have released a chemical into the soil that affected the plants' growth. This could be tested by wrapping the magnets in plastic bags in the experimental group and puting bags alone in the control group.
Second, if the magnets were not anchored, the two would heve squeezed together against the base of the plant. This would have caused stress in the plant, causing it to release growth hormones that might have caused this. This could be tested by anchoring the magnets.
Third, the magnets could have attracted metals from the soil. Depending on where the magnets were in relation to the roots, it could cause a great increase or decrease in the metals that the plant absorbed. I have no idea how you could test this hypothesis.
Many other organisms DO use magnetism. Pigeons, dolphins, bees, and monarch butterflies contain particles of magnetite, a magnetic mineral. All of these animals make long journies. Monarch butterflies only make it once, so it is not from learning. Homing pigeons are capable of finding their way home without being able to see. All are great navigators. It is believed that salmon find the stream they were born in using magnetism.
Some bacteria that require low oxygen and live in the bottom of ponds also use magnetism. They have a string of particles of magnetite that acts like a compass. It aligns with the earth's magnetic field so that the bacteria always swims in a downward motion.
Thank you for the question,
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