I recently executed an experiment in which I collocated 20 lentil seeds in independent Petri boxes with an agar agar solution, all of it located in a clinostat (a slowly rotating device used to simulate microgravity conditions, where they rotated perpendicularly to the ground (gravity). The objective was to see in what direction did the roots grow under the effects of microgravity, since geotropism didn't have a fixed direction to head to. At the end of an entire cycle, the forces (gravity in 360°) applied to the seeds would turn out to be equally strong, in opposite directions, so it would come down to nearly zero. However, after many executions, without having any functional problem with the clinostat, the seeds simply didn't grow roots while being in the agar agar in the Petri boxes. I tried different agar agar solutions, different concentrations, more & less quantity so that the seeds would have a thin air layer; and I also added copper sulphate to prevent fungi from appearing, also varying its concentration. Afterwards, I tried using an already germinated seed so that the radicle had direct access to the solution and to the air layer. Nevertheless, after several executions, only a few seeds grew their roots and I din't find a concrete explanation for this experiment not being successful.
I expected having the roots in the experimental group to grow in many different directions, not being constant. As in the other hand, I expected the control group to grow roots in the same direction, going downwards, being in the same system (clinostat) without having the rotations going on.