Influence of Environmental Conditions in the Artificial Light Room on the Growth of Soybean Plants

Abstract

The author experimented on the environmental conditions in the artificial light room of the phytotron at the Hokkaido Agricultural Experiment Station to make clear the distribution of air velocity, air temperature, radiation energy and influence of vegetation on these factors.Air is provided into the room from the perforated side wall and expelled into the opposite wall of same style. At the standard condition which has no pot-trolley and soybean plants in the room, the fairly uniformal distribution of air velocity and temperature are measured. Along air stream from the supply wall to the return wall, air temperature rises only 0.6°C in the standard condition. At the growing condition which has pot-trolleys and soybean plants, the air temperature between plants rises in the range from 1.4 to 1.9°C according to the distance from supply wall. This elevation of temperature is primarily owing to the insufficiency of air velocity. To depress this phenomenon, more sufficient air velocity should be secured.Soybean plant height varies from 48 to 111cm with their places. Under favourable conditions, stem elongation is accelerated to receive more radiation energy from the lamps, causing as much as a three times difference in the enlargement of plant height.The soybean growth was comperatively tested at the artificial light room, at the natural light room and at outdoors. It was proved that the environmental conditions in artificial light room were inferior to the outdoor conditions, but superior to the conditions in natural light room from the view of the increment of dry matter per day, grain yield and its component characters such as pod number per plant and grain weight.Normal growth processes from germination to maturity are attained under the condition of this artificial light room.