Analysis of transient plant movements by holographic interferometry

Abstract

HOLOGRAPHIC interferometry is a photographic technique which can be used to measure minute displacements of objects¹. Williams² has shown holographic interferograms of painted wheat shoots, but in his initial work there was no attempt to make quantitative measurements of either plant displacement or, more importantly, transient plant response. The present work demonstrates the potential of holographic interferometry in plant movement analysis by showing previously unobtainable data on the bending and short term transient response of a mature, slow moving plant. Our results suggest that the holographic interferometric technique may provide the means to measure accurately such important plant movement parameters as velocity and displacement with much higher resolution than is available from any other method. In addition, the technique substantially improves the time resolution of plant movement analysis, thus enabling more detailed observation of the tropic response as a function of time.