Abstract
In order to determine the effect on the nicotine synthesis, excised root tips were incubated in the media varying in concentration of nitrogen, sugar and gibberellin. The results obtained were as follows. 1. The contents of total nitrogen and total sugar in the big root tips of several varieties were much higher than those in the fine roots, while comparison of nicotine content and the ratio of nicotine-nitrogen to total-nitrogen between big roots and fine ones showed that the values in the former were lower than in the latter. 2. The amount per milligram of synthesized nicotine in the root tips was highest in the roots grown in rooting media with low nitrogen level and those grown in the elongation media with high leyel of nitrogen. 3. The sugar level in the medium seemed to give more effect than nitrogen level. Considerable amount of nicotine was decomposed in the medium of 0.5 per cent sugar level and optimum concentration of sugar for nicotine synthesis was found to be around 2 per cent. 4. With increasing gibberellin concentration from 0 ppm to 1000 ppm, the activities of nicotine synthesis decreased.
