QUELQUES OBSERVATIONS SUR LE DÈVELOPPEMENT DES CULTURES IN VITRO DE MOELLE DE TABAC EN PRÉSENCE D'AUXINE ET DE KINÉTINE, EN ÉCLAIRE-MENT RELATIVEMENT MONOCHROMATlQUE

Abstract— In a previous publication we have presented some results on tobacco pith tissue cultures grown in relatively monochromatic light (around 4350,5250, 6600 and 8000 Å).
This paper points out specially that cultures subjected to a continuous blue light period of 12 days only, followed by a darkness period of 29 days, grew no more than cultures exposed to the same radiations during the 41-day period of the experiment.
The growth was only 67 per cent of that of tissues grown in the darkness.
The morphologic and histologic observations showed the same differences between the cultures grown in blue light conditions and the cultures grown in the other light conditions, as also reported elsewhere.
Observation of bud developement on stem segment cultures in vitro of willow, grown under these relatively monochromatic light conditions, together with these histologic studies, leads us to believe in a possible gibberelline action in blue light.