On the photoperiodism in paddy rice plant : 1. Photoperiodic responses of principal varieties cultivated in Tohoku region, Japan

[摘要] 1. A comparative study of photoperiodic sensitivity of principal rice varieties was made by means of short-day vs. long-day treatments of the plants. 2. Of the 40 varieties tested, naturally earlier maturing varieties were found, in general, to be more sensitive to the treatments, while the medium and the later ones were less sensitive ; the result just agreed with those hitherto obtained by many previous investigators. 3. On the other hand, however, some of the varieties showed different tendencies. 4. According to the types of response observed in our experimentation, the varieties may be classified into following three groups: 1) A group sensitive to both short-day and long-day conditions, 2) A group more sensitive to short-day, but less to long-day conditions, 3) A group less sensitive to short-day, but more to long-day conditions. 5. Generally speaking, with a few exceptions, the earlier and the medium varieties proved to be more sensitive to long day, but less sensitive to short day, while the later varieties were more sensitive to the short day but less to long day.

[学科分类] 农业科学（综合）