Der Einfluss des Lichtes auf die Bildung von Blattprimordien am Vegetationskegel der Keimlinge vonSinapis alba L

Summary

Seedlings of white seeded mustard (Sinapis alba L.) have been investigated with respect to the influence of light (red, far-red, white) on the rate of formation of primordia at the apex. The results show that the formation of primordia is strongly increased by light and that this control is exerted mainlyvia the phytochrome system and the “high energy reaction” )=blue, far-red reaction) of photomorphogenesis (cf.Mohr 1962). Apparently photosynthesis can also be important in the case that the supply of organic material limits the rate of those growth processes which have been induced by the photomorphogenetically effective radiation.

The morphological appearance of the stem apex and of the youngest primordia is the same in light and dark. It is concluded that light increases the rate of primordia formation by promoting the mitotic activity in the apical meristem. Growth of the primary leaves of the mustard seedling is also greatly promoted by light. Both the phytochrome system and the “high energy reaction system” are involved. Experiments indicate that this control by light is exerted in a way similar to the light control of the growth of the cotyledons (Mohr 1959b).