Movements of Zoospores of Phytophthora capsici

Abstract

A new photometrical device for measuring the tactic aggregation of zoospores of Phytophthora capsici Leon. is described in this paper.An annular diaphragm (×100) of Nikon phase contrast microscope was employed for dark ground illumination and reflected light intensity in the microscopic field was measured by an ordinary exposure meter for microscopic photography. Specimen chamber for the microscopic observation was devised by combining glass slide with cover glasses.When tips of plant roots, platinum electrodes, or capillary tubes containing plant extracts were introduced into the zoospore suspension in the specimen chamber, various patterns of tactic aggregation of zoospores were observed. The light reflected by zoospores in the dark ground illumination was photometrically read and recorded.The photometrically plotted diagrams directly reflected the density of zoospore population in the specimen chamber. This method would certainly be applicable to the kinetic analysis of the tactic aggregation of zoospores.