Abstract
1. The intensity of supplemental light which affects the flower initial and vegetative growth of strawberry was studied using varieties Kogyoku and Red Star. The range of intensity of artificial light used was 2 to 100 luxes. The long day treatment (24 hours: all-night illumination in addition to natural day-length) was applied from September 1 to October 31.
2. The limit of light intensity which is able to inhibit the flower bud differentiation differs between the varieties. It seems to be about 20 luxes in Red Star and 10_??_20 luxes in Kogyoku.
3. The stronger the intensity of supplemental light, the more vigorous the vegetative growth, especially the growth of the crown. The limit of light intensity effective to vegetative growth seemed to be about 10 luxes.
