Nursery management after the first transplant. In the first transplanting stage (including the second transplanting of slow-growing trees), the seedlings are still very small, and the main goal of cultivation is to promote the development and rapid growth of seedling roots, so the focus of tending management is loosening soil and weeding and fertilizer and water management.
First, loosen the soil and weed. Because the canopy of seedlings is not closed, weeds grow rapidly, which will compete with seedlings for nutrition and will inevitably affect the growth of seedlings. Therefore, it is necessary to loosen the soil and weed in time, so as to weed early, small and small. Weeds should be removed from paths and open spaces except the boundary. Irrigation after rain, when the topsoil is slightly dry, loosen the soil immediately, and the appropriate depth is 5 ~ 10 cm. Be careful not to damage the roots of the seedlings. After loosening the soil and weeding, repair the trail in time, cover the soil in the frame and level it.
Second, fertilizer and water management. The production of green seedlings has high benefits. Judging from the sales price of seedlings in recent years, the average DBH of seedlings below 8 cm is around 10 yuan, and the price of seedlings with good tree specifications of 8 ~ 10 cm is higher. Thus, as long as the DBH of seedlings is 1 cm, there will be at least 10 yuan. Therefore, under the condition of excellent soil texture, strengthening fertilizer and water management and promoting the vigorous growth of seedlings can effectively improve economic benefits. Pay attention to the combination of base fertilizer and topdressing when applying fertilizer. The base fertilizer can be put into the planting pit when transplanting, or applied in autumn and winter every year. Topdressing mainly uses compound fertilizer, which is applied in the growing season or in holes. Top dressing should be carried out at least three times a year. If possible, topdressing can be done before each germination and after the new leaves turn green in the growing season, so that the seedlings grow faster. The last topdressing every year is completed one month before the autumn and winter seedlings stop growing. So as to lignify the seedlings in time. Fertilization should be combined with irrigation in order to exert the effect of fertilization.
(2) Tending management of seedlings after secondary transplanting. In the second transplanting stage, the seedlings have basically reached the specification requirements of green seedlings, and the main goal of cultivation is to make the roots of seedlings dense, have certain dry and crown-shaped healthy seedlings, and have no pests and diseases. Therefore, the focus of tending management is fertilizer and water management, pest control and pruning.
First, pest control. Pest control must implement the policy of "prevention first, comprehensive prevention", do a good job in the prediction and prevention of pests and diseases, and cultivate high-quality and healthy seedlings for urban greening. Do a good job in soil and seedling disinfection, and the seedlings can only be used after passing the quarantine inspection. Strengthen field management, reduce the breeding conditions of pests and diseases, make seedlings grow healthily and enhance stress resistance. Reasonable close planting, appropriate thinning, improve permeability conditions and reduce the occurrence of pests and diseases. Pests and diseases should be prevented in time.
Second, shaping and pruning. Requirements for plastic finishing. The shaping and pruning of urban greening seedlings is mainly based on natural tree shape, so that the crown width/height ratio is appropriate, the main branches are evenly distributed, the trunk is complete and the crown is full. In the process of cultivating street tree seedlings, it is required that the crown is complete, the trunk is straight and symmetrical without scars, and the main and lateral branches are clear. The height of the branch point can be gradually moved up by pruning until the specified fixed dry height, which generally takes 2 ~ 2.5 meters. The natural height of seedlings should reach 4.5 ~ 5m, and the crown width/height ratio is generally 1/3 ~ 1/2, and the crown width should be above 2.5m.. Garden ornamental seedlings, the height of stem is lower than that of street trees, generally less than 2 meters, requiring full crown. The crown height ratio is generally 1/2 ~ 2/3, and the crown width is more than 2.5 meters. It can also be cultivated into multi-stem type or curved stem type. Conifer seedlings should be cultivated into full crown type or low stem type, and the main shoots should be well cultivated. Generally, it is not advisable to repair more. It is worth noting that in the process of trunk cultivation, when the seedlings do not meet the predetermined specifications, the height of branch points should not be trimmed in one step, because excessive pruning will weaken the tree potential and affect the growth. At the same time, pruning should be carried out step by step when the tree is strong, so that the wound can be easily healed and scars on the trunk can be avoided due to pruning. The period of plastic surgery and pruning. Generally, plastic surgery is the main method in the dormant period, and the pruning amount can be slightly heavier. The growth period is mainly to adjust the tree potential, and the pruning amount should be light. For seedlings, in addition to transplanting pruning, whether dormant or growing, try not to prune, so as not to weaken the tree; Seedlings with weak tree potential shortly after transplanting are generally not suitable for pruning; Slow-growing saplings should not be felled again.
(3) Pretreatment of seedlings before they leave the nursery. The green seedlings cultivated according to the above procedures can reach the standard of high-quality seedlings and are the standard seedlings for urban greening. However, it will take a long time for this kind of seedlings to recover and achieve the ideal greening effect after they are transplanted to the site for planting. If this recovery period is arranged in the seedling field, the seedlings can achieve the greening effect immediately after being planted on the site without restoration. At present, this practice has been realized in the field of bagged and potted shrub seedlings, while in the field of large-scale arbor greening seedlings, several seedling conservation farms in Nanhai and Huadu have been doing this work in recent years, which is the goal pursued by urban greening seedlings in the future. The basic practice is to dig up the qualified seedlings from the nursery, trim the trunk, height, crown width and root system as required, plant them in large containers and cultivate them in the maintenance field for 3 to 6 months. When the seedlings survive and grow again, and the tree shape meets the requirements, they become finished seedlings.