Abstract
The temperatures of the head leaves of cabbage in a field can be higher than the air temperature during the day due to solar radiation. The decrease in freezing tolerance by solar radiation was confirmed by shading the head leaves. Although the highest leaf temperature without shading was about 28°C during the day, the leaf temperature with shading was lower than the air temperature. Deacclimation of the cabbage was also reduced by shading. Shading (31% of full sun) with cover materials stretched horizontally above the ground for 6 days increased the freezing tolerance in comparison with non-shading. These results demonstrate that the head leaves of cabbage grown in winter are often exposed to high temperatures on sunny days, affecting the freezing tolerance of the cabbage. Short-term deacclimation of cabbage induced by high leaf temperatures in winter can be transiently controlled by shading.
