Picea koraiensis: management techniques at seedling stage

(1) shading: red spruce seedlings like shade and dampness. after the seedlings are unearthed, the seedling preservation rate of proper shading is 30% 40% higher than that of full-light seedlings, the seedling height increases by 32%, and the tender leaves are bright green. Generally, when 50% of the seedlings emerge, they begin to set up day-covering curtains to cover the shade until they are removed in the early and middle of July. If it is difficult to cover and obtain materials, you can also plant tall crops (such as corn) along the bed instead of Reed curtains. In some areas, there are sufficient water sources and convenient irrigation. Watering with a small amount of water 2 or 4 times a day and mastering timely and appropriate watering can also make full-light seedling cultivation successful.

(2) topdressing irrigation: topdressing can be carried out in the middle and last ten days of June, with 4.5 kg urea per mu, divided into 2 times, and rinse in time after topdressing to avoid burning the stems and leaves. Before the first ten days of June, under the condition of dry weather, it is better to water 2mi 4 times a day, a few times, and enter the rainy season after the middle and late June. According to the changes of the weather, the times of irrigation can be gradually reduced, and the amount of irrigation can be increased appropriately, irrigated every other day, timely irrigation, and keep the topsoil on the bed moist. To the end of July or early August, fertilizer and water should generally be controlled to promote the full Lignification of seedlings.

(3) Frost prevention: Baiyinaobao and Northeast Forest region in Inner Mongolia are located in high cold, the final period of late frost is about late May, and late frost has a great effect on seedlings. According to the observation of Tieli nursery in Heilongjiang Province, when the temperature dropped to 0 ℃ 10 cm above the bed, the newly planted seedlings suffered 10% Mel 13%, and when the temperature dropped to-2 ℃, the newly grown shoots of 2-3-year-old seedlings suffered 3% Mel 10%. The growth of seedlings damaged by frost is poor, and the seedling rate is very low. Therefore, it is necessary to make a good prediction of frost and use smoking method or grass cover in time.

(4) Prevention and control of diseases and insect pests: the main underground pests such as blight and mole cricket at seedling stage should give priority to prevention and comprehensive control (see the relevant contents of seedling disease and insect pest control for details).

(5) overwintering and cold prevention: the cold prevention of red spruce seedlings is an important measure to ensure the seedlings to survive the winter safely and reduce losses. More measures should be taken to cover the soil in the seedling bed trail. The specific measures are as follows: turn up and break the soil on the seedling trail, pour the seedlings to one side, cover the soil evenly, and its thickness should be 4 cm higher than that of the seedlings. The time of cold prevention by soil mulching should not be too early, otherwise the seedlings are prone to heat and mildew, usually in late October or early November before soil freezing. The time to remove the soil should not be too early or too late. Generally speaking, the cold soil should be removed twice before Grain Rain. In order to prevent the physiological drought of seedlings caused by the dry wind in spring, the seedlings should be irrigated in time after the soil is removed.

(6) changing the bed: the seedlings of more than 1 year old should be replanted in the middle or late April, and the sap should be carried out before the sap flows. The density of changing bed is 200 plants per square meter, plant spacing is 5 cm, row spacing is 10 cm, and about 80,000 seedlings can be produced per mu. In order to avoid transplanting the nest root, the main root of the seedling should be trimmed properly and keep 8ml 10cm.

According to the experience of Tieli nursery, the root system of the bed-changing seedling is developed, the stem is short and stout, and the survival rate of afforestation is 6% higher than that of the remaining bed seedling. The annual growth is 3% higher. Therefore, at present, more than 2-year-old seedlings are cultivated by changing beds and transplanting.