Mother tree selection

According to the purpose of selection, select the mother tree with strong fruit and full seeds for seed collection.

(1) To cultivate timber forest, the mother tree requires compact tree shape, tall tree body, straight trunk, high branches, exuberance and no pests and diseases.

(2) To cultivate landscaping varieties, the mother tree requires an open crown, full trees, rich seasonal changes in leaf color and long leaf color cycle; Early discoloration period.

(3) potted ornamental type, the mother tree requires a short tree and a strange tree shape.

Time and method of seed collection

The seeds were harvested from late October of 10 to early October of 1 165438 when the fruit turned from green to brown. Collect seeds on the ground by naturally falling off or tapping twigs. After seed collection, the branches and leaves should be removed first, then spread in an indoor ventilated and dry place for natural drying for 2 ~ 3 days, and then winnowing. Before storage, the seeds were naturally dried indoors for 5 ~ 8 days, so that the water content of the seeds was reduced to below 65438 03%. Nursery land should be sandy loam or light loam, with flat terrain, water supply and deep and fertile soil layer. Before sowing, the nursery should be deeply ploughed, weeds should be removed, and sufficient base fertilizer (2000~2500kg/hm cake fertilizer) should be applied. After the nursery is leveled, a seedbed with a width of 120cm and a height of 20-25cm will be built.

sow seeds

Planting can be carried out in late autumn and early spring. Autumn sowing is followed by harvest, and it germinates in the first half of March of the following spring, with high seed germination rate and emergence rate and long seedling growth period; But it is vulnerable to attack by birds and animals. Spring sowing should be carried out when the rain comes and insects are frightened, not later than late March at the latest. Covering the seedbed with shading net with shading rate of 50%-75% after sowing is beneficial to soil conservation and seedling management in the later stage. The sowing amount is 150~200kg/hm2 to keep the soil moist and facilitate seed germination.

Seedling management

Drill, the row spacing is 20cm, the thickness of soil cover is 0.5cm, and the grass cover is permeable. 25 ~ 30 days after sowing, when the seeds germinate, the grass should be uncovered and the seedlings should be tempered in time to prevent bird damage. In the seedling stage, it is necessary to space seedlings in time, loosen the soil and weed, and irrigate and topdressing. The peak period of seedling growth is from July to late September. Weed 3-5 times a year at seedling stage, topdressing 65,438+0 times after each weeding, and the last fertilization 65,438+0 times can be carried out in early August. Zelkova schneideriana seedlings will branch at seedling stage and need to be pruned in time. Site selection for Zelkova schneideriana planting should choose the site environment with deep soil layer, loose, fertile and good drainage, such as plain, beach, gully slope and all around, and avoid the site with poor drainage and easy seasonal water accumulation and flooding.

Carry out soil preparation

Before planting, the land should be deeply ploughed, raked and fully fertilized. Determine the row spacing of plants, pay off and ditch to build beds and dig pits. The size of the hole depends on the volume of the root system of the seedling. Generally, the size of holes should be 2 ~ 3 times the volume of seedling roots.

Initial planting density

1 annual Zelkova schneideriana 50cm× 150cm transplanted seedlings (13000 plants /hm).

Planting method

The plant spacing should be100cm×100cm (10000 plants /hm2) or should be planted in early and middle March. When planting, put the seedlings into the hole, first return the soil to the hole 1/3, then gently lift the trunk of the seedlings upward to stretch the roots, and then return the soil to the hole 2/3. After that, the soil in the cave will be filled with water. When returning to the soil, return to the topsoil first, then return to the core soil, and tread lightly when returning to the soil. Annual seedlings should be planted shallowly. In the early land of Nangang slope of the Yangtze River, when the original roots of seedlings are buried in the soil, the planting depth is 0~4cm. Ridges and ditches should be built and planted in places with high groundwater level in summer. In arid areas and easy-to-dry land blocks, the planting depth can be slightly deeper, and the roots are buried in the soil for 5~ 10cm. When planting, cofferdams should be made around the roots to facilitate watering during continuous drought and prevent rainwater loss when it rains. For individual seedlings whose aboveground parts have died, but their roots are still alive, they should be cut off and uprooted in time.

Density adjustment

After two years of planting, seedlings should be transplanted alternately. The growth space of seedlings should be expanded through thinning and density control. The plant spacing should be adjusted to 100cm×200cm(5000 plants /dm) or 100cm× 150cm(6700 plants /hm2), which should be paid attention to during transplanting. After that, the density will be dynamically adjusted according to the site conditions and cultivation objectives (market specifications) every year. The row spacing of 3-year-old seedlings was adjusted to 200cm×200cm(2500 plants /hm2) or 200cm×300cm( 1700 plants/hm2); Five-year-old seedlings should be adjusted to 200cm×400cm( 1200 plants /hm2) and 200cm×300cm( 1700 plants/hm2); Seven-year-old seedlings should be adjusted to 400cm×400cm(600 plants /hm2) and 400 cm× 600 cm. Reasonable density control can ensure the good development of trees, cultivate excellent tree species and improve the application quality of green seedlings. Intertillage weeding

Weeding and loosening soil is an important measure for the maintenance of Zelkova schneideriana seedlings (young trees). Weeding and loosening soil can prevent weeds from competing with young trees for soil moisture and nutrients, improve soil aeration, improve rhizosphere environment for root respiration of seedlings, promote the reproduction of soil microorganisms and the decomposition of soil organic matter, and promote the growth of seedlings. The beech nursery needs to loosen the soil and weed 3 ~ 4 times a year. After weeding and loosening the soil every time, weeds should be covered in the rhizosphere to preserve moisture.

Prevention of premature drainage

Although Zelkova schneideriana can adapt to a certain arid climate, it still needs to adapt to a humid climate. When the climate continues to be dry, it is necessary to water and irrigate in time to prevent the seedlings from losing water and dying. In rainy season, it is especially necessary to ditch and drain in time to reduce waterlogging. Too high groundwater level and too much soil moisture will have serious adverse effects on Zelkova schneideriana.

rational application of fertilizer

Seedlings of Zelkova schneideriana need timely fertilization in the fast-growing season. The principle of fertilization is: in the early stage of seedling growth, choose quick-acting fertilizer; Applying nitrogen fertilizer in the middle growth period (fast growth period); In the later stage, phosphorus and potassium fertilizer were added to promote the good wood properties of seedlings.

Fertilization amount: In the afternoon, the average amount of N, P205 and K20 applied per mu of L-year-old seedlings was 7kg, 3kg and 4kg respectively, and the amount of decomposed manure was 1500kg. Fertilization mode is light before, stable after control. Topdressing is usually 4-6 times a year. For two to perennial seedlings, N, P20s and K20 are applied at 15~20kg, 6 ~ 8kg and 8 ~ 15 ~ 20k g per mu each year, and 2000~2500kg of heat and fertilizer are used.

control of insect

No serious diseases of Zelkova schneideriana have been found. More than 20 species of pests have been found at the seedling stage, mainly including black cutworm, aphid, inchworm, leaf moth, poisonous moth, bag moth, scarab and so on. Insecticides such as 80% dichlorvos 1000 times, 90% trichlorfon 1200 times or 2.5% triadimefon 6000 times can be sprayed in time to control leaf-eating pests. For underground pests, it is necessary to water the black cutworm or trap it with poison bait.

Trimming and shaping

Pruning of Zelkova schneideriana should be carried out in the early summer growth season or winter dormancy period, and the winter dormancy period is the best time. With the growth of tree age, the bottom branches with the height of 1/3 should be pruned year by year within 2-3 years, and pruning should be continued for many times. According to the cultivation goal of Zelkova schneideriana, the requirements for pruning and tree cultivation are: planting landscaping tree species, keeping the height below the main branch at 2.5~3m, and removing the inner branches, transverse branches, parallel branches, diseased branches and dead branches in time. Land selection

The afforestation site of Zelkova schneideriana should be acidic and neutral soil with thick and wet soil layer, and the foothills, valleys or other places with relatively gentle terrain can be selected for afforestation in mountainous areas; If the soil in urban greening is poor, foreign soil can be used for planting.

Carry out soil preparation

When constructing general timber forest, 1 year-old seedlings are adopted, and the tree hole size is 50×50×60cm；; The specifications of tree holes of urban greening seedlings are 80×80× 100 cm, and organic fertilizer is applied to the holes, 10-30 kg.

density

The beech timber forest can be made into pure forest or mixed forest. The initial planting density is 2×2 m or 2×3 m, and proper close planting can inhibit the growth of lateral branches, which is beneficial to high growth and cultivate straight stem shape. After thinning, the density can reach 4× 4m or 4× 3m, which can cultivate large-diameter timber. The planting density of street trees in urban greening is usually 3× 4m or 4× 4m.

plant

The planting time should be in spring, about the beginning of spring. When building a mixed forest, it should be planted every other tree, so that a pure forest can be formed after thinning. Water, seal and moisturize after planting. The big seedlings of urban greening should also be supported by poles to prevent them from shaking.