Circumnutations under free-fall conditions in space?

Regular growth movement, so-called circumnutation, of plants and plant organs is a very general phenomenon. The origin of circumnutations is, however, unclear. Three different types of model are discussed in relation to some experimental results on circumnutations. It is suggested that an experiment in space, under free-fall conditions, should be done on different species showing circumnutations in order to discriminate between the models.