Dose response behaviour for polarotropism of the germ tube of the liverwort Sphaerocarpos Donnellii aust.

The dose response behaviour for polarotropism of the unicellular germ tube of Sphaerocarpos was studied in blue and near UV. At constant intensities the response is proportional to the logarithm of the exposure duration, and at constant exposure durations the response is proportional to the logarithm of intensity. Neither a polarotropic response to wavelengths > 550 nm, nor a significant influence on response to blue of a pre-, post-, or simultaneous-irradiation with red or far-red could be observed. Also a dark period was without any effect on the polarotropic response to blue. Growth responses under linearly polarized light are described.