INDOOR GARDENS USING THE HIMAWARI SUNLIGHT COLLECTION AND TRANSMISSION DEVICE

摘要

Japan has had quasi-indoor gardens (known as tsubo-niwa) from ancient times. The aim of our research was to maintain a similar sort of continual garden indoors. Since sunlight is the most favorable light source for plant growth, we used the Himawari sunlight collection and transmission system to simulate tropical rainforest lighting conditions in a darkroom. We used Himawari light in place of the light patches (light: dark = 1:5), with supplementary artificial light in place of diffracted light. Theamount of light necessary to maintain homeostasis of plants was 0.33 E.m~(-2). day~(-1) for the Himawari light alone, and 0.43 E.m~(-2).day~(-1) for the artificial light alone. On the other hand, new growth was observed with only 0.30 E.m~(-2).day~(-1) by combining the Himawari light with the supplementary light. An indoor garden raised under these conditions showed continued plant growth for two years. Continual indoor gardens should be useful for improving the surroundings not only in rooms and offices, but also in places where direct sunlight cannot be obtained, such as deep underground spaces.