What are the key technical points for tending and managing Korean pine (Pinus koraiensis) seedlings?

The tending and management of Korean pine (Pinus koraiensis) seedlings is as follows: the emergence period of Korean pine takes about 20 to 30 days. When the temperature is above 16°C, germination is most vigorous. Attention should be paid to watering to prevent drought, and to preventing damage from birds pecking. During the seedling stage, roots grow relatively fast; the main root can reach 10 cm long, accounting for about 40% of the annual growth, and can produce 4 to 5 lateral roots. However, the height growth of the seedlings is very small. Therefore, the resistance of the seedlings is very poor. Attention should be paid to watering to lower the temperature, preventing sunscald, and timely topdressing and loosening the soil and weeding. From the time Korean pine seedlings form terminal buds until the growth rate declines, it lasts about 2 months. Leaf volume increases, seedling stems thicken, the main root elongates, lateral roots grow abundantly, and two rounds of lateral roots appear. The fertilizer demand of the seedlings increases, so topdressing should be carried out in time. Also strengthen management such as intertillage, soil loosening, and weeding. First-year Korean pine seedlings are small and weak and generally cannot be shipped out of the nursery for afforestation (2- to 3-year-old seedlings are commonly used for afforestation), so overwintering protection for the seedlings is extremely important. Korean pine is more cold-tolerant, but afraid of drought, especially in early spring when the aboveground parts of the seedlings have already begun to sprout but the soil has not yet thawed, so water cannot be supplied in time, causing physiological drought. Therefore, the method of covering the seedlings with soil is commonly used to protect the seedlings. The method is: first break up the soil in the path and bury the seedling stems, then bend the seedlings to one side and press them down with soil, about 10 cm thick, to the extent that the seedling leaves are no longer visible, and be careful not to allow wind to pass through. Wait until the following spring when the soil has thawed to a depth of more than 10 cm before removing the soil. In recent years, some people have also applied warming agents sprayed on the leaf surface to control leaf transpiration and prevent the seedlings from drying out, with very good results.