Effect of Solar Radiation to Side Surface of Multi-cavity Container on Root Zone Temperature and Growth of Cryptomeria japonica Seedlings

Abstract

Since multi-cavity containers used in open-field cultivation receive direct sunlight on the side surface, the seedlings located near the outer margin have higher root zone temperatures than others. Our investigation focused on the root zone temperature and seedling growths in containers with and without shading on the sides along the four cardinal directions. During the day, without shading from the sides of the container, the root zone temperature of the outer margin seedlings was warmer than that of the central seedlings. Conversely, in containers with sides shielded from sunlight, the root zone temperature did not differ depending on the seedling position. Furthermore, in seedlings near the outer margin of the container whose sides received direct sunlight, the roots were reduced, while height tended to be small. Thus, during the open-field cultivation of containerized seedlings, shading the sides of the container from sunlight is effective in maintaining a suitable temperature for growth.