高性能growth cabinetおよびそれを用いた環境要因と葉音との関係解析

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For studies on biotronics of fundamental problems in environmental control in biology, high accurate control of environmental factors is demanded. The growth cabinet is considered as an effective tool for such a purpose. This report presents a newly developed growth cabinet with capacity of high accurate control of air temperature and relative humidity, and also present analysis of relationships between leaf temperature and environmental factors with the use of the growth cabinet. From analyses of the capacity of the growth cabinet, following performances were obtained. 1) It became possible to control temperature from -5℃ to 40℃ with accuracy of ±0.5℃. The P.I.D. control action contributed to remove off-set and cyclic variation in temperature control. In the case of program control, temperature gradient of 10℃/30 min was obtained. 2) Relative humidity was controlled from 40% to 80%±3%~±5％ at temperature range from 10℃ to 40℃. In program control, falling and rising gradient of relative humidity was 10%/15 min. 3) Wind direction, velocity and distribution were kept uniform by 16 fans installed at the side of air supply compartment. Wind velocity ranged from 0.2 m/sec to 0.5 m/sec. 4) The canopy provided 45 fluorescent lamps of 40 W (FLR 40 SW-SDL-AP/M) and 8 incandescent lamps of 100 W. At 50 cm above floor 20,000lux (110 μW/mm^2) of light intencity was obtained. Leaf temperature was measured under various conditions of air temperature, relative humidity, light and wind by micro-thermistor which was inserted into the cotyledon of Cucurbita maxima seedling. Under the condition of 70% relative humidity in darkness, the leaf temperature was lower than the air temperature at air temperature of 20℃, 30℃ and 40℃, but at the air temperature of 10℃, there was no difference between the leaf temperature and the air temperature. The difference between the leaf temperature and the air temperature was larger at higher temperature. When the leaf was illuminated by a tungsten lamp with the intensity of 220 μW/ mm^2, the leaf temperature was higher than the air temperature at air temperature of 10℃, 20℃ and 30℃. The difference between the leaf temperature and the air temperature was smaller at higher temperature. When the air temperature was changed from 30℃ to 40℃ under the illuminated condition, the leaf temperature once became 40.5℃ and fell to 38.5℃ and gradually converged to 39℃. When the relative humidity was changed from 80% to 40% at the air temperature of 40℃ under illuminated condition, the leaf temperature fell from 39℃ to 35.5℃ and gradually converged to 36.0℃. When the relative humidity was changed from 80% to 40% at the air temperature of 30℃ under the same condition, the leaf temperature fell from 34℃ to 32.5℃. Thus, the effect of relative humidity on the leaf temperature was larger at higher temperature and was scarcely observed at the air temperature of 20℃. The leaf temperature of 26.5℃ under condition illuminated by the tangusten lamp with the intensity of 273 μW/mm^2 at air temperature of 20℃ and relative humidity of 60%, rapidly fell to 25℃, 24℃, 23℃ and 21.5℃, when the wind verocity was 0.6 m/sec, 1.2 m/sec, 2.4 m/sec and 4.8 m/sec, respectively. Thus the leaf temperature was remarkably affected by wind, and the effect of wind on leaf temperature corelated to wind verocity. From these results, it could be estimated that the leaf temperature was remarkably affected by air temperature, light, relative humidity and wind. These findings suggest that the air temperature is not enough to be taken as the index of "the temperature" in the examination of the temperature effects on the plant, but such plant temperature as the leaf temperature should be taken into consideration for the exact analysis of the temperature effects.
九州大学の論文

高性能growth cabinetおよびそれを用いた環境要因と葉音との関係解析

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