INFLUENCE DES ÉCLAIREMENTS APPROXIMATIVEMENT MONOCHROMATIQUES SUR LE DEVELOPPEMENT DES TISSUS DE MOELLE DE TABAC CULTIVBS IN VZTRO EN PRESENCE D'AUXINE ET DE KINETINE

Abstract— The influence of relatively monochromatic light (around 4350, 5250, 6600 and 8000 Å) on the growth of cultures of tobacco pith tissues with auxin and kinetin was studied. The cultures were subjected either to continued light or to alternations of 16 hr light with 8 hr darkness, or to a dark period followed by continuous light.
The influence of blue light was especially noted. The development in volume and weight of the cultivated tissues in blue light is generally less than in the other conditions (except for one or two exceptions); the differences are attenuated when a light period alternates with a period of darkness; the callus tissues of tobacco pith exposed to blue light are always chlorophyllic with a dense and hard appearance and histological studies show that tissues grown in blue light are mostly made of large cells with thick cell-walls and many nodules while under the other conditions the tissues are mostly made of very small cells with few or no nodules.
These differences seem related to specific photoreceptors rather than to energies delivered to the cultures.