Rotation axes for analysis of gravity effects on plant organs.

Epinastic curvatures of branches of Coleus blumei Benth. and the growth pattern of wheat (Triticum aestivum L.) seedlings on clinostats were used for bioassay of rotation methods for preventing growth responses to gravity. Tumbling a plant end over end was found to be just as effective as rotation about its horizontal axis. The results support the reliability of data from experiments in which an entire plant is rotated about a single horizontal line with only part or none of its immature tissues in horizontal orientation to gravity.