Effect of Light on Growth of Excised Root Tips Under Sterile Conditions

Abstract

1. Diffuse light was favorable to the continued growth of root tips in a modified Pfeffer's solution containing 2 per cent glucose, or the same solution to which 80 ppm or 400 ppm of autolized yeast were added. 2. Anthocyan developed in some of the excised corn roots in the light, but in none in the dark. 3. The anthocyan pigment was present in the root cap, at points where secondary roots were to emerge or had emerged, and at the base of the root, but not in the meristematic region. 4. The longest period a root tip was grown was 149 days, through ten periods of transfer, in diffuse light in the modified Pfeffer's solution containing 2 per cent glucose and 400 ppm of autolized yeast. 5. Roots which remained attached to the grain during the first two weeks grew for a longer time than those grown under excised conditions from the start. One such root was grown in the dark for 133 days, 119 in excised condition.