タバコの開花に関する生理学的研究 : 第2報 湛水処理期間の相違が発育反応に及ぼす影響

抄録

In these investigations, relationship between total number of leaves of a tobacco plant (bright tobacco var. BRIGHT YELLOW), which was closely related to time of flower initiation and length of duration in which plants were grown on water-logged soil, was examined under field conditions in normal season. In the first experiment, the three different sized seedlings (with 8, 10 and 12 leaves) were subjected respectively to water-logging for various durations (0, 1, 3, 6, 15 and 20 days) after transplanting, in order to determine the influence of both growth stage of seedling and length of treatment duration. As the results, in case of 8 leaver-seedling, these treatments had relatively little or no effect upon the number of leaves and in 12 leaves-seedling, it tended to decrease in total number of leaves markedly with length of durations, whereas in 10 leaves it was slightly decreased in case of shorter duration (1-3 days), but reversely increased in longer duration (15∼2O days) compared with that of normal plant. In the second experiment, all combination of three growth stages (8, 10 and 12 leaves), two periods until beginning of treatment from transplanting (0 and 14 days) and two water-logged durations (3 and 15 days) were tested in order to recognize above-mentioned relationships. As the results, total number of leaves, which were treated at 14 th day after Transplanting was decreased compared with that treated just at the time of transplanting, except in case of three days duration with 8 leaves-seedling and fifteen days with 12 leaves. Especially, the remarkable decreases of total number of leaves was caused by only three days treatment and in these plants was observed earlier blooming than normal, if the growth stage of plant shown by external leaf number reached more than 12 leaves. In the third experiment, the three different sized seedlings as above mentioned were transplanted at the same time, and then in 12 leaves-seedling were treated just at the time of transplanting, where as the same treatment was begun at 7 th day after transplanting in 10 leaves-seedling and at 14 th day in 8 leaves, when their external leaf number reached to 12 leaves and continued respectively for various durations (0, 1, 3, 6, and 15 days). As the results, in longer duration of treatment as fifteen days, there was less variation in decrease of total number of leaves among seedlings with various growth stages However, it showed in shorter duration that total number of leaves was decreased markedly in case of 12 leaves-seedling. From these results, it was concluded that there was a limiting factor showed by the growth stage of tobacco plant for decrease of total number of leaves caused by long duration of water-logging, as shown in previous paper, and in one stage before this limit, increase of total number of leaves occurred, but in another stage over this limit, water-logging duration required to induce the remarkable decrease was reached to only three days.