Detailed Explanation of Key Techniques for Red-barked Spruce Seedling Cultivation

I. Properties and Uses

The red-barked spruce is also known as "red-bark stinker." It belongs to the Pinaceae family and is an evergreen tree that can reach a height of 30 m. The branchlets are hairy or hairless, without white powder. The leaves are four-angled, with stomatal lines on all four sides, pointed tips, and a length of 1.2 cm-2.2 cm. The cones are ovate-cylindrical or long ovate-cylindrical, 5 cm-8 cm long; the seed scales are obovate, with rounded or slightly pointed tips, and the exposed parts are smooth without longitudinal stripes. It is a major tree species in the forests from the Changbai Mountains to the Lesser Khingan Mountains in Northeast China. It is also distributed in Korea and eastern Siberia, Russia. The wood is light, soft, and fine-textured, suitable for construction, furniture, papermaking, and other uses, and it is also grown as an ornamental tree.

II. Cutting Propagation Methods

The cutting time should be in early spring after new shoots emerge. Cut 15 cm-long cuttings and carry out cutting propagation inside a plastic greenhouse. To raise the ground temperature, fresh horse manure can be placed under the bed, maintaining a ground temperature of 25°C-35°C; a humidity of about 90% is optimal. The plastic greenhouse should be tightly covered and not opened frequently, so as to avoid reducing humidity. When cuttings are inserted, dipping them in 1000 μg/g indolebutyric acid hormone and ABT Rooting Powder No. 1 gives relatively good rooting results.

III. Seedling Cultivation Techniques

1. Seed treatment. Use the "snow storage method" to bury seeds. First, choose a place with a low groundwater table and shelter from wind and sun, and dig a storage pit with a depth of 80 cm, while the length and width depend on the amount of seed. The pit is best dug in the autumn of the previous year. Between January and February, spread 10 cm-15 cm of snow on the bottom of the pit, then mix the seeds with snow at a ratio of 1:2 or 1:3, stir evenly, and place them into the pit. After filling, pile snow into a mound shape and cover it with straw curtains and other materials. About 1 week before the sowing season, take the seeds out, mix them with moist sand, and stratify them at room temperature of about 15°C for 4-5 days. Water when the sand dries, and turn them 1-2 times a day. When 20%-30% of the seeds have cracked open, they can be sown.

2. Sowing. Use the no-cover sowing method. First prepare the seedbed as required. Do not water the base; instead, rake the moist bed surface so that it forms an even, uniform surface with strip-like ridges and grooves. To facilitate sowing, mix an appropriate amount of dry sand into the seed-sand mixture before sowing and stir evenly. When sowing, sow, press (with a wooden roller), cover with a curtain, and water immediately so that the seeds are in close contact with the soil. Before the seedlings emerge completely, water frequently and always follow the principle of "small amounts, many times," keeping the bed surface moist at all times.

Practice has shown that no-cover sowing produces seedlings faster and more uniformly than cover sowing. Generally, seedlings appear 8 days after sowing, 80% can emerge in 15-20 days, and emergence is basically complete in 20-25 days, with no lodging of seedlings ever occurring. According to statistics, the seedling yield of no-cover sowing is higher than the regulatory standard compared with cover sowing, generally 22% higher, and in some cases 2-3 times higher.

3. Seedling-stage management. When more than 60% of seedlings have emerged, remove the reed curtains so that the seedlings receive full light. If there is no high temperature or drought, carry out full-light seedling cultivation throughout, which is better than long-term shading, making the seedlings sturdy, with well-developed root systems and strong resistance to disasters. To prevent late frost damage, water before cold air arrives to increase the soil heat capacity. If frost damage occurs, water before the sun comes out so that the seedlings form ice columns, which then gradually melt, and the frost damage can be eliminated.

During the seedling growth period, follow the principle of "small amounts, many times" and water regularly and quantitatively. Especially in dry weather, do not apply "horse-racing water" (light, rapid surface watering). For mechanical watering, use high pressure, fine nozzles, and fast valves to prevent the water flow from washing out the seedlings. After the seedlings emerge completely, loosen the soil and remove weeds in time to prevent weeds from competing for water and nutrients, thereby promoting seedling growth. To prevent sunscald, an electric-contact mercury thermometer can be used, connected to a sunscald alarm, with the thermometer set to 36°C. When the ground surface temperature reaches 36°C, the alarm goes off, and watering should be carried out immediately to cool the temperature.

In terms of pest and disease control, adopt the method of regulating the ecological environment to restrict the spread of pests and diseases. In addition to seed disinfection, strictly prevent disasters caused by non-infectious ecological factors from being mistaken for infection by pathogenic bacteria. For infectious diseases, solve them by regulating ecological factors such as water, fertilizer, air, heat, and light, and prevent chemical pesticides from polluting the environment. In this way, the seedlings can develop well and have strong resistance to pests and diseases.