A FULLY AUTOMATED DUAL‐WAVELENGTH PHOTOMETER FOR PHYTOCHROME MEASUREMENTS AND ITS APPLICATION TO PHYTOCHROME FROM CHLOROPHYLLCONTAINING EXTRACE

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Abstract
The photometer described here measures phytochrome photoreversibility of as many as 20 samples fully automatically. Monochromatic light of two laser diodes (670 and 780 nm) is used as a source for the measuring light beam. The whole measuring procedure is controlled by a computer linked to a lock‐in amplifier. This arrangement permits a rather simple construction and allows automatic zeroing and sample change.In addition the application of a Triton phase partitioning method to allow phytochrome photoreversibility mea surements of extracts of green tissue is described. A single phase partitioning with a chlorophylYphytochrome mixture reduced chlorophyll concentration to less than 10%. Repeated phase partitioning of crude extracts from green moss protonemata reduced chlorophyll content to less than 2% while leaving the phytochrome concentration almost unchanged. In some instances this method has advantages over polyethyleneimine precipitation, which is commonly used to obtain chlorophyll‐free extracts.