[An in vivo study of phytochrome in seeds of Pinus nigra Arn by differential spectrophotometry].

Phytochrome photoconversions Pr→Pfr and Pfr→Pr can be measured by differential spectrophotometry in "dry" seeds (6% water content) of Pinus nigra Arn. A red light irradiation given before imbibition induces germination when the seeds are subsequently wetted and kept in darkness.In continuous darkness the phytochrome content shows a drastic increase at the beginning of moistening.The detectable pigment is entirely in the Pr form. The normal Pfr→Pr dark reversion is observed. Pfr destruction does not take place.