Abstract
The author examined the after-effects of the shortening the day length during seedling stage upon the growth of barley plant (var. Shirochinko) especially its influences on root length. Plants were grown in root-boxes fertilized as follows; (1) standard, (2) double the standard, (3) without N, (4) without P, (5) without K. The short day treatment hours a day (6) was commenced in a few days after their germination and continued for 30 ays. The main results were as follows : (1) The treatment made the total length of roots of all plots longer than that of non-treatment. (3) Heading and flowering commenced earlier in the plants of the plots such as without N, without P and without K, when plants were treated.