Very short term measurement of root growth with magnified time-lapse image capture system

To date, various kinds of electric responses of animal have been reported. Galvanotaxis of paramecium and electric stimulation of neuron or muscle of vertebrate are well studied. On the contrary, there are few reports on the responses of plant to electric stimulation. R.sativus and E.camaldulensis are among them. In our previous study, root growth of Eucalyptus seedling seems to enhanced by 20% in 50Hz a.c. electric field of around 50 V/m range. However, standard deviation of the data was so large that reliability about electric root growth enhancement was difficult to demonstrate clearly. To make a precise measurement, averaging in a ensemble is needed. However, effect of individual difference is inevitable in the experiment. In this study, we developed a magnified time-lapse image capture system to measure the root growth in a short period of time. This system enables growth measurement in very short time compared with some days long. We investigated the resolution and the accuracy of the system rapid growth measurement. The maximum resolution of the system was less than 4μm. The root length of the R.sativus, whose growth enhancement in electric field was well established, was mesured. From the result of 2 hour measurement, root growth measurement with 10% standard deviation in 5 minutes was demonstrated. This figure means the new system enables over 800 fold faster measurement with better accuracy.