（transplanting of nursery stock）

（林民智）

Cultivation of seedlings or seedlings in different beds in order to obtain seedlings of certain specifications technical measures. Seedlings cultivated in this way are called transplanted seedlings. Transplantation of seedlings can increase the nutritional area of ??the above-ground and underground parts of the seedlings, improve nutrient, moisture, light and ventilation conditions, promote the development of lateral roots and fibrous roots, avoid excessive main root growth, accelerate the growth of the above-ground parts of the seedlings, and form good seedling stems and stems. Seedling crown, improve seedling yield. The number of transplants of seedlings and the length of cultivation time depend on the growth rate of the seedlings and the requirements for the seedlings in afforestation and greening. Fast-growing tree species such as eucalyptus, casuarina, camptotheca, etc. only need to be transplanted once and cultivated in the transplanted area for several months to meet the requirements. Slow-growing tree species such as Korean pine, spruce, fir, bamboo cypress, Lujun pine, oil fir, cedar, golden pine, etc. generally need to be transplanted 1 to 2 times and cultivated for 2 to 4 years before they can become seedlings. Large seedlings used for urban greening and tree planting on all sides require multiple transplants and cultivation. The main techniques for cultivating transplanted seedlings are as follows:

Soil preparation and application of base fertilizer

In order to facilitate the root development of transplanted seedlings, the transplanting area should be located in an area with deep, loose and fertile soil. The soil preparation depth should be deeper than the sowing area, generally 30 to 35 cm. Apply enough base fertilizer.

Transplanting Season

Transplantation can be done in spring, autumn and rainy season, but it is generally better to transplant in spring and autumn when the above-ground part of the seedlings has not yet sprouted and the underground part begins to grow. At this time, the soil moisture conditions are good, the temperature is not high, the transpiration of the above-ground part of the seedlings is small, and the water in the body is easy to maintain a balance. The seedling slow-down period after transplantation is short and the survival rate is high. The order of transplanting various tree species in spring and autumn should be determined based on the order of their germination. Those that sprouted early were transplanted first, and those that sprouted late were transplanted later. Generally, coniferous saplings should be planted first, deciduous broadleaf saplings second, and evergreen broadleaf saplings last. In areas where the climate is warm and humid in autumn, the seedlings can also be transplanted immediately after the above-ground part of the seedlings stops growing. Because the seedling root system has not stopped moving at this time, the root system can resume growth after transplantation and is easy to survive. However, in areas where the soil freezes in winter, it is not suitable to transplant in autumn. Evergreen trees can be transplanted during the rainy season. In northern China, transplantation should be done at the beginning of the rainy season. In the south, transplantation should be done at the beginning of the plum rainy season. Transplantation is best done in the early morning and evening on cloudy or calm wind days. Do not transplant on rainy days or when the soil is too wet to avoid muddy soil, which will affect the root system of the seedlings and damage the soil structure of the nursery, reducing the survival rate and growth rate of the transplanted seedlings.

The transplanting density

is determined based on the growth rate of the seedlings, the size of the seedlings, the development characteristics of the seedling crown and root system, the purpose and years of cultivation, climate, soil and other conditions. Generally, the density of fast-growing tree species is smaller than that of slow-growing tree species; the density of broad-leaved tree species is smaller than that of coniferous species; the density of large seedlings is smaller than that of small seedlings; the density of seedlings with spread crowns and developed lateral fibrous roots should be smaller; the density of those with a longer cultivation period is smaller than that of those with a shorter cultivation period; In places with a warm and humid climate and fertile soil, seedlings grow faster and their density should be smaller; if animal-drawn tools or machine-drawn tools are used for seedling care, their density should also be smaller. Commonly used plant spacing is 10 to 30 cm, and row spacing is 15 to 50 cm.

Transplanting method

When the seedbed is dry, water should be filled first to soak the seedbed, and the seedlings should be raised when the soil is semi-dry but not wet. The seedlings should be graded immediately and transplanted in different sizes. , making it grow evenly and reduce differentiation. Before transplanting, the seedlings should be properly pruned, and the roots that are too long and damaged by splitting should be cut off. The remaining length of the root system is generally 15 to 25 centimeters. Some branches and leaves of evergreen broad-leaved trees should be pruned. The above-ground parts of broad-leaved trees with strong germination ability, such as paulownia, poplar, and black locust, can be pruned appropriately or cut dry and transplanted. There are two types of transplantation: bare root transplantation and soil transplantation. Current-year evergreen seedlings and most deciduous tree species can be transplanted with bare roots. When transplanting bare roots, special attention should be paid to keeping the root system moist. Generally, the roots should be slurried with mud immediately after the seedlings emerge, and placed in a container lined with moist moss or straw. They can be taken as they are planted; if possible, they can be placed in a sealed truck or sealed box. , and sprinkle water to moisturize, which can better protect the root system of the seedlings and improve the transplant survival rate. Some tree species that are difficult to survive with bare-root transplantation, as well as evergreen saplings and tree species with tap-root systems that are transplanted for the second time, as well as rare tree species such as Araucaria and cedar, should be transplanted with soil lumps. There are two types of transplantation methods: manual transplantation and mechanical transplantation. For seedlings with well-developed root systems, use hole planting or trench planting; for seedlings with slender main roots and less developed lateral roots, use transplanting cones or transplanting shovels for hole planting or seam planting. However, the root system must be fully stretched to survive. The depth of transplantation should be 1 to 2 cm slightly deeper than the original seedling ground diameter (soil mark). After transplantation, irrigation should be carried out in time to shorten the seedling slowing period and improve the survival rate of seedlings.

Tending and management

The number of cultivating and weeding should be determined according to the soil, climate conditions and the number of weeds. After transplantation, cultivating should generally be done 5 to 6 times in the first year, 4 times in the second year, and then reduced year by year. The height of the seedling stems should depend on the purpose. For street trees, it is generally 3 to 4 meters; for shelterbelts, it is generally 1 to 2 meters. Strapping is an effective measure to improve the stem shape of seedlings. For deciduous tree species with strong germination ability, if the stem shape of the seedlings does not meet the requirements, the growth is not strong or the above-ground parts are seriously damaged, they can be leveled to the ground when they germinate in the early spring of the year after transplantation. stubble so that a straight and strong trunk can regrow. After the stubble is leveled, it should be covered with 3 to 5 cm of fine loose soil to prevent water evaporation and drying of the cut. After the sprouts sprout, select one strong and upright one as the main trunk, and remove the rest.

For certain tree species used for landscaping, when the main trunk of the seedlings grows to a certain height (usually about 2 meters), the tips can be cut or the top buds removed to inhibit high growth, accelerate diameter growth and side branch expansion, and make the crown open and symmetrical. The shaping of the tree crown can be determined according to the purpose. Street trees can be allowed to grow into a natural crown shape or an umbrella shape; ornamental tree species can be shaped into a fan shape, cup shape, candlestick shape, cone shape, spherical shape, etc.; those used as shelterbelts are mostly natural Crown shape.

Out of the nursery

There are two types of seedlings out of the nursery: those with soil lumps and those without soil lumps (bare root seedlings). Deciduous broad-leaved tree species often do not have soil lumps when they are planted, while evergreen tree species generally have soil lumps. Regardless of whether the soil is lumpy or not, the root system should be kept intact as much as possible. For large seedlings with lumps of soil, the diameter of the lump is generally 6 to 12 times the diameter of the rhizosphere. If it is dug and planted immediately, it does not need to be wrapped; if it is transported over a long distance, it should be wrapped with straw curtains or straw ropes to prevent the soil from spreading. (See seedlings coming out of the nursery)

Bibliography

Sun Jin and others edited: "Garden Nursery", China Construction Industry Press, 1982.