Detailed Explanation of Qinghai Spruce Sowing and Seedling Cultivation Techniques

Qinghai spruce, of the genus Picea in the pine family (Pinaceae), is an evergreen tall tree. First-year twigs are pale greenish-yellow at first, later turning pinkish-yellow or pinkish-brown, more or less hairy; leaves are four-angled linear, slightly curved or straight, 1.2-3.5 cm long, 2-3 mm wide, with obtuse tips or blunt pointed tips, rhombic in cross-section, with stomatal lines on all four sides; flowers are unisexual, monoecious; cones are conical, cylindrical or oblong-cylindrical, pendulous, 7-11 cm long, 2-3.5 cm in diameter; seeds about 3.5 mm long, wings about 1.3 cm long, young cones purplish-red. Flowering period is April to May, and cones mature in September to October.

Qinghai spruce is the main forest regeneration tree species and barren-hill afforestation tree species in the Qilian Mountain forest region, playing an extremely strong role in water conservation and soil and water retention. Because it is evergreen year-round and its crown is conical with a graceful shape, it is widely used in urban greening, garden planting, beautiful village landscaping and highway greening.

I. Seed Collection and Processing

In the natural forest region of the Qilian Mountains, Qinghai spruce seeds mostly mature 7-10 days before White Dew. Seed trees should preferably be selected from 30-50 year old plants that are robust in growth, excellent in trunk form and free of pests and diseases. After collection, the cones should immediately be spread out in the seed yard to dry in the sun, turned several times a day, until the scales loosen and open and the seeds fall out; use an iron fork to shake out the seeds. After winnowing and removing debris, dry the pure seeds and place them in a cool, dry storage room.

II. Nursery Site Selection

The nursery site should be set in flat terrain with convenient water sources and soil preferably of sandy texture and light clay loam with relatively high soil quality. It is forbidden to set up a nursery in places where cold currents gather, in waterlogged lowlands, or at wind gaps with damaging winds.

III. Soil Treatment

For the selected nursery site, in the previous autumn use a four-wheel tractor to plow deeply to 30 cm, and pick out all grass roots and stones. In combination with land preparation, apply 20 kg of ferrous sulfate, 1.5 kg of 3911 and 1.5 kg of methyl isothiophos per 667 sq m for soil treatment.

IV. Land Preparation and Bed Making

The seedbed uses a flat bed, 2.5 m wide and 20 m long, with ridges 30 cm wide and 30 cm high, and the bed surface is required to be level. Apply 5000 kg of decomposed sheep manure and 60 kg of phosphate fertilizer per 667 sq m, evenly spread on the bed surface, then plow deeply to 30 cm. After the bed is made, irrigate thoroughly; when the soil no longer sticks to tools, carefully shallow-plow to achieve a level bed surface with loose, fine, crumbly soil.

V. Seed Treatment and Sowing

Seed pre-germination. Generally, seeds are pre-germinated 10-15 days before sowing: soak in warm water at 30-40°C for 1-2 days and nights, select seeds by water, remove shriveled seeds and other debris, soak seeds in 0.5% copper sulfate solution for 30 minutes, rinse several times, then mix with sand and pile for pre-germination. Note to stir several times a day; when about 30% of the seeds have broken white, they can be sown.

Sowing. Spring sowing is the main method, preferably from late April to early May. Use the drill sowing method, open furrows with a sowing width of 15 cm and row spacing of 10 cm; the furrows are required to be level and uniform, with a depth of 1 cm. Evenly scatter the treated seeds into the furrows, then cover with a mixture of disinfected, sieved humus soil and fine sand mixed at a ratio of 1:3. The covering soil thickness is 1 cm, then properly compact with a wooden roller so that the seeds and soil are fully in close contact. The sowing rate is 15-20 kg per 667 sq m.

VI. Seedling Stage Management and Pest and Disease Control

Covering. Immediately after sowing, cover the seedbed with disinfected Achnatherum splendens, and sprinkle water in time to maintain suitable temperature and humidity in the seedbed. After most seedlings emerge, remove the covering in batches, and set up a shade shed before removing the covering.

Building a shade shed. When most seedlings have emerged, drive stakes and set up frames, and place shade netting on the frames, using overhead shading. The shade shed is 1.5 m above the ground, and a light transmittance of 30%-40% is better.

Frost prevention. According to weather changes, actively prevent frost by smoking, irrigation or covering.

Disease prevention. Qinghai spruce seedlings are susceptible to damping-off disease, so after the seedlings emerge, spray Bordeaux mixture or 0.3% ferrous sulfate solution once every 4 days, or spray with 1000-fold dexon solution, with 900 g per mu for root drenching; after drenching, spray with clean water to help the solution penetrate the seedling roots. After spraying ferrous sulfate, the solution on the seedlings must be washed off with clean water within 30 minutes to avoid phytotoxicity.

Weeding. One-year-old Qinghai spruce seedlings are tender and weak, so weeding is a key step. Whenever weeds are found on the seedbed, they should be pulled out in time; weeding must be thorough and clean, while protecting the seedlings and not damaging the root system.

Overwintering management. If summer management is good, the seedlings can become lignified by autumn. Overwintering is relatively easy, but cold protection is still needed in winter; that is, in mid-October, cover with disinfected straw curtains. In late April of the next year, when wild grass turns green, remove the curtains and grass. First remove the curtains for 4-5 days, then remove the covering grass in two stages; for the second removal of grass, it is better to be late than early to prevent spring cold.

VII. Summary

For Qinghai spruce seedling cultivation in the Qilian Mountain forest region, the density of current-year seedlings should reach more than 2000 plants per sq m. Spruce sown in the current year is prone to seedling damping-off disease, so symptomatic application of pesticides, timely disease prevention, and meticulous seedling management are required.