Enhanced Phytochrome Sensitivity and Its Reversal in Amaranthus albus Seeds.

Seed of Amaranthus alus L. develop an enhanced sensitivity to the farred absorbing form of phytochrome after prolonged imbibition at temperatures >32 degrees C. The enhanced sensitivity developed at 40 degrees C could be reversed by subsequent treatment at 20 degrees C and similarly reestablished by repeating a 40 degrees C treatment. It is concluded that relative sensitivity to the far-red absorbing form of phytochrome may be readily manipulated in seeds of A. albus.