Expert: Walter Hintz - 3/27/2008

Question
I'm an Asian form 4 student (equivalent to grade 10) currently studying the geotropism of plants.

I'm told that plant roots show positive geotropism, however, experiments have been done in space and it is found that plant roots still grow normally without the effect of gravity. How can they do that? And does this kind of show that gravity is not a factor that affects plant growth?

Another question is, although plant shoots are negatively geotropic, would gravity slows down their growth (like pullling them downwards)? And what about us? Is our growth encumbered by gravity pull?

Thank you very much.

Answer
Hi Rita; I was unaware of the space study regarding geotropism so I cannot answer you question but it seems to show that there other factors besides gravity.  Gravity of course has an effect on shoots also.
We have never observed the growth of a human in the absence of gravity but i believe that the force is not enough to inhibit growth