1. The classification of Adzukibean varieties based on responses to daylength was carried out and several characteristics of the varieties with regard to these responses were studied. 2. The early varieties were apperared to have less sensitivity to short-day and the late varieties were showed to have great sensitivity. The order arranged in series, from the early to the late of varieties, coinsided with the order of sensitivity to daylength among all varieties in Adzukibeans. 3. M 2 group, intermediate variety, is an unstable group which is very sensible to the effect of daylengh and temperature, and its flowering date is especially liable to vary by the different temperature from year to Year. 4. The grade of sensitivity to daylength among varieties in every region showed the latitudinal adaptation. While in comparison with Manturian and Hokkaido ecotypes, the former showed slightly greater than the latter for the sensitivity to short-day. This difference may be due to the determinate and indeterminate plant type. The early varieties distributed in the southern region have the greater sensitivity to short-day than the early varieties in the southern region have the greatest sensitivity to short-day. 5. Under the stronger level of short-day, the threshold of temperature to flowering showed no difference among varieties, but under long-day treatments, the threshold of temperature to flowering gradually increased according to the degree of lateness of the varieties. This may be due to the varietal difference for responses to photoperiod influenced by temperature. 6. The grade of sensitivity to short-day was decided by the difference of flowering dates between short- and long-day treatments. The flowering date showed no difference at the short-day plot. Therefor, the different sensitivity to daylength among varieties was appeared by the difference of the delay of flowering under long-day plot. In this test, the experiment was taken place under the natural condition of seasonal temperature. So, the delayed varieties received the different temperature on subsequent growth to flowering in comparison with the earlier varieties which have already finished their flowering. Under different conditions, we cannot compare the characteristics of the varieties. But in this experiment the thresholds of temperature on flowering from early to late among varieties, were just arranged in the order of the seasonal increase of temperature. From the reason above, when we want to test the relative order of sensitivity to daylength, it may be possible to use the changing temperature under seasonal condition. 7. The order of the grade of earliness and the sensitivity to daylength among varieties, coinsided with each other. This shows that the selection by the long photoperiod on the summer solstice in Central Japan and the test of 16h30m long-day plot under natural temperature, have the seame effectiveness each other. Then, the test of the earliness may substitute for a practical method of the test of the sensitivity to daylength.
