Catalysis of the phytochrome dark reaction by reducing agents.
D003624:Darkness; D005288:Ferredoxins; D005182:Flavin-Adenine Dinucleotide; D009243:NAD; D010777:Photochemistry; D010786:Photoreceptor Cells; D010940:Plant Proteins; D013053:Spectrophotometry; D013447:Sulfites; D014316:Tritium
D005288:Ferredoxins; D010940:Plant Proteins; D013447:Sulfites; D009243:NAD; D014316:Tritium; D005182:Flavin-Adenine Dinucleotide