EFFECTS OF NONIONIC SURFACTANTS ON TOBACCO ROOTS
The nonionic surfactant Tween 20, when present in culture media at 0.001%, occasionally stimulated growth and (or) nicotine synthesis of isolated roots of N. rustica and whole plants of N. tabacum. It was also found to stimulate root respiration and the succinoxidase activity of root mitochondrial fractions. Its effects were compared with those of its metabolically active ingredients oleate and laurate and with those of an assumed metabolically inert surfactant Triton X-100. Tween 20 showed both types of effects, the toxicity and respiratory stimulation being characteristic of oleate–laurate, and the growth stimulation being also produced by Triton X-100. No oleate deficiency in the tissues was evident, since neither oleate nor biotin stimulated growth. Modes of action are briefly discussed and the use of 0.001% nonionic surfactant in culture media is recommended.