PHOTORECEPTORS. “The perception of the luminous sign in plants is made by photoreceptors, which include phytochromes (phy), cryptochromes, phototropins, ZTL/ADO family proteins, in addition to a protein family of photoreceptors responsible for absorbing the ultraviolet light (UV-B). Phytochromes are the main photoreceptors, and they are responsible for absorbing the red (R) and far-red (FR) radiation.”
http://www.scielo.br/scielo.php?pid=S0100-83582016000100191&script=sci_arttext