Abstract
Humidity distribution in a plant population is complicated with many environmental factors and physiological functions even in controlled environment. The present paper deals with analyses of humidity distributions in the cucumber plant population under different air currents with reference to plant growth. The humidity in the plant population was increased by irradiation and evaporation from soil, and the humidity distribution was remarkably influenced by air current. Increased air velocities higher than 0.9 m sec-1in lateral air current made the humidity in the plant population close to that of controlled air. However, these velocities were estimated to exceed the optimum velocity for plant growth. When the air velocity was reduced to 0.2 m sec-1, the horizontal gradients of humidity were smaller in downward air current as compared with those in upward and lateral air currents. Therefore, it is certain that each of the plants in the population can be exposed to almost the same humidity in downward air current. On the other hand, the plant growth was more uniform in downward air current than in upward and lateral air currents. From these facts, it could be estimated that the downward air current is preferable for minimizing the horizontal differences in humidity in the plant population, in order to make plant growth more uniform for exact analyses of plant responses to environmental factors.
