Physiological Studies on Flower Formation of Tobacco : VI. On the cause of promoting effect of water-logging on the flower formation of tobacco.

[摘要] Experiments were carried out to examine the production and flower promotion of ethanol in day-neutral tobacco plant grown on the water logged soil. The seedlings of the variety Xanthi with thirteen leaves were employed as materials throughout these experiments. The results were as follows: 1) The alcohol constituents in the steam distillates from tobacco materials, were analyzed specifically by the gas chromatograph procedure. The methanol was detected both in the water-logged plant and in the control, whereas the ethanol was detected exclusively in the former. The ethanol content increased with the increasing duration of water-logging. 2) In order to examine the effect of ethanol on the flower formation of tobacco grown on the soil culture, the roots of the seedlings were applied to the soil surface with the aquatic solution of ethanol for fifty days. The concentrations of ethanol were from 1.8 % (w/v) to 3.6 % (w/v). From this work, it was found that a marked promotion of flowering and the decrease of total leaf number were caused by the application of ethanol. The degree of the promotion was not varied within the range of concentrations examined. 3) In order to examine the effect of the duration of application, the roots were kept in the basal medium contained ethanol at 2.4 % (w/v) for three, six, nine and twelve days respectively. After various periods of culture, the seedlings were transferred to the basal medium without ethanol added, and grown until the date of flowering. From this work, it was found that a marked promotion of flowering and the decrease of total leaf number were caused by the three day's treatment. The decrease of leaf number, however, was not varied within the range of days examined. The promotion of flowering, on the other hand gradually decreased with the prolonged application period. 4) The effect of the broader range of concentrations was investigated with the same way as in the preceding work. Ethanol solution was diluted with the culture solution to give 0.3, 0.6, 0.9, 1.2 and 1.5 % (w/v) of ethanol. Treatment with ethanol was conducted for a five days and after being held for that period, it was found that a promotion of flowering and the decrease of total leaf number were caused in any solution but the maximum response of flower formation was not detected within these ranges of concentration. Moreover, the same results were obtained when the ethanol was applied to the roots of tobacco grown on the soil in pot. From the results mentioned above, the author assumes that the promotion of flowering in tobacco whose root systems are subjected to the water-logging treatment, may be caused by the effect of ethanol which have been endogenously produced in the roots as the result of anaerobic respiration.

[学科分类] 农业科学（综合）