Re-examination of the Effect of Daily Rotation in the Horizontal Plane on Growth of Cyclamen Plants and Etiolated Avena Seedlings

Abstract

JONES1, in New Zealand, has reported that rotating cyclamen and bean plants in a clockwise direction about a vertical axis at one revolution per day resulted in a loss of turgidity and accelerated the death of leaves, whereas normal growth was maintained when the direction of rotation was anti-clockwise. In other experiments it was shown that when etiolated Avena seedlings were rotated in darkness in the same manner, clockwise rotation caused a reduction in root and shoot extension growth, while, by contrast, anti-clockwise rotation brought about increased growth. Jones did not interpret these results, which were reported as being distinct and unequivocal, and they do not appear to be gravitational or centrifugal responses. However, Jones's technique of slowly rotating plants about a vertical axis has recently been used2,3 in experiments to support claims that in some plants, notably cereals, growth and root orientation is affected by the horizontal component of the magnetic field of the Earth. To seek independent confirmation of Jones's findings, similar experiments have been carried out in Griffith, Australia, at latitude 34.18° S., using cyclamen and etiolated Avena seedlings. Negative findings are reported here.