Fundamental Studies on the Sun-scalded Injuries of Garden Trees after Transplanting

Abstract

The experiments were tried to find the some rational methods which would prevent the transplanting trees from sun-scalded injuries and make the growth better.
Cinnamomum camphora, Zelkova serrata and Prunus donarium var. spontanea were used in this experiments.
After transplanting, we measured the tree temperature (cambium temperature) with the thermocouple, and water contents of cortical tissues by dry weight method.
We tried to find out the lethal tree temperature, and direction and time which sun-scalded injuries occurred.
We also tried to find out the relation between the lethal tree temperature and the water contents, solar radiation and air temperature.
1. The tree temperature of transplanting trees is higher than non-transplanting.
2. Solar radiation and air temperature are more imp ortant factors which influence the tree temperature.
3. High temperature is recorded on the south-west and west side at 14: 00-16: 00 o'clock during the time the late in July to the beginning of September.
4. The tree temperature is different according to the height of measuring spot from the ground and the direction of boughs.
5. The lethal temperature of Cinnamomum camphora is between 52 and 55°C in dark brown bark of trunk at the height of 1. 5m (φ9cm), and in green parts at the height of 1.0m (φ3cm), 42-45°C is lethal. But in the part of the trunk at the height of 0.2m (φ14cm) where the cork layer develops well, the tree temperature of 55-57°C is not lethal.
6. The heigher the tree temperature becomes, the lower the water contents of the cortical tissues becomes,
7. The trunkcovering with rice straw, cheese cloth and reed, and white washing kept the tree temperature considerably lower, and somewhat steadier, than non-trunkcovering trees, and prevent deterioration of the cortical tissues.
It is important to shade from the burning sun.