THE ‘HIGH‐IRRADIANCE RESPONSE’ IN ANTHOCYANIN FORMATION AS RELATED TO THE PHYTOCHROME LEVEL

Abstract

Abstract— The involvement of phytochrome in light‐mediated anthocyanin synthesis in the mustard seedling ( Sinapis alba L.) under inductive conditions (law of reciprocity valid) was shown previously (Drumm and Mohr, 1974). In the present paper the hypothesis (Hartmann, 1966) is checked that light‐mediated anthocyanin synthesis in continuous high‐irradiance far‐red light (‘high‐irradiance response’) is also due exclusively to phytochrome. The data indicate that the effectiveness of the far‐red light is indeed a function of total phytochrome [ P total ]* and therewith [ P fr ]*. The data are not consistent with the suggestion (Schneider and Stimson, 1972) that photosynthesis (in particular, photosystem I) is involved in the ‘high‐irradiance response’ of photomorphogenesis.