Langya elm breeding and afforestation seedling cultivation method

Abstract

The invention discloses a yellow ulmus pumila breeding and afforestation seedling cultivation method, which comprises the following steps: taking mature yellow ulmus pumila seeds for sowing, carrying out first transplanting when two pairs of true leaves of each seedling grow and the seedling height reaches 5cm, and keeping the distance between the transplanted seedlings at (4-6) cm * (20-30) cm; 2-3-year-old strong seedlings are selected and transplanted for the second time, roots are cut off before transplanting, all lateral branches are removed, and the transplanting line spacing is (1-1.5) m * (1-1.5) m; after the forest trees are closed and grow for 1-2 years, third-time transplanting is conducted, the transplanting line spacing is 2-3 m * 2-3 m, and exposed roots of the soil balls are cut off during transplanting. According to the yellow ulmus macrocarpa breeding and afforestation seedling cultivation technology, the yellow ulmus macrocarpa seed germination efficiency can be improved, the seedling survival rate can be increased, and excellent landscape forests, water and soil conservation forests and commercial forests can be created.

Description

Technical Field

[0001] The invention relates to a method for breeding and afforestation seedlings of Langya elm, belonging to the technical field of forest cultivation. Background Art

[0002] Langya elm (Ulmus chenmoui), a deciduous tree endemic to China, is found only in Langya Mountain in Anhui Province and Baohua Mountain in Jiangsu Province. It grows in deciduous broad-leaved forests on limestone hills at altitudes of 100-250 meters. With a well-developed root system and tolerance to drought and infertility, Langya elm thrives in sites with exposed rock and shallow soil, but grows faster in deep, fertile soil. With its tall, upright trunk and beautiful shape, Langya elm is a natural feature of Langya Mountain and is widely used for timber, soil and water conservation, and landscape architecture. In recent years, mature Langya elm trees have frequently died. Furthermore, Langya elm's ability to propagate by cuttings is weak, and sowing is currently the primary method of propagation. However, the reproductive capacity of its seeds decreases with age. Under natural conditions, seed germination rates are low, and seed harvesting time, sowing time, and sowing temperature all significantly affect emergence rates. Consequently, understory seedling regeneration is poor, leading to the tree being listed as a Class III endangered species by the state. Although a tall tree, Langya elm suffers from a lack of distinct trunk and soft, heavily branched branches in its early stages of growth, which can easily lead to deformed tree forms. This not only compromises its aesthetic appeal and ornamental value, but also hinders its potential for growth. Therefore, research on the improved breeding of Langya elm is of great significance. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for breeding and afforestation seedlings of Langya elm.

[0004] The technical solution adopted in the present invention is: A method for breeding and afforestation seedlings of Langya elm, comprising the following steps: (1) Take mature seeds of Langya elm and sow them. When the seedlings have two pairs of true leaves (the seedlings are about 2-3 cm tall at this time) and when the seedlings reach 5 cm in height, transplant them for the first time. During the transplanting process, pinch off the root tips. The spacing between the seedlings after transplanting should be kept at 4-6 cm × 20-30 cm. For the seedlings left in the bed that have not been transplanted, when they grow to 30-40 cm in height, cut off the main roots. Cutting off the roots can promote the growth of the root system, increase the number of lateral roots and fibrous roots, and help improve the survival rate of Langya elm. By observing the Langya elm seedlings that died after afforestation, more than 95% of the seedlings were not cut off. (2) Select 2-3 year old strong seedlings for the second transplant. Cut off the roots and remove all side branches before transplanting. The transplanting row spacing is 1-1.5m*1-1.5m; (3) After the trees have grown for 1-2 years after becoming densely covered, they are transplanted for the third time. At this time, the seedlings are generally 2-3m tall, and the transplanting row spacing is 2-3m*2-3m. When transplanting, they are transplanted with the soil ball and the exposed roots outside the soil ball are cut off.

[0005] During the propagation and cultivation of Langya elm, multiple transplanting is very important. Seedlings that have not been transplanted grow sluggishly, while Langya elms that have been transplanted multiple times have straight trunks, beautiful tree shapes, and significantly higher growth rates and diameters at breast height than those that have not been transplanted. By combining root pruning with multiple transplanting, the ultimate yield rate of Langya elm can reach over 90%. The main purpose of root pruning is to promote the growth of lateral roots, thereby increasing the survival rate of transplants. The beds are kept for 2-3 years, mainly because the branches of Langya elm seedlings are soft and easy to bend during growth. Planting them densely in the beds can prevent the seedlings from bending. Multiple transplanting can also better change the growth space of the seedlings, achieve natural pruning with the right density, reduce scars on the trunk caused by pruning, and regulate the growth of the trunk and crown of Langya elm. Typically, Langya elms that have undergone three transplants reach a height of approximately 4 meters by the time they are planted, with a trunk height of approximately 2.5 meters and a crown width of 3-4 meters. Pruning is rarely necessary, and the trunk remains straight and flawless. However, seedlings that have not undergone multiple transplants often lack significant trunk growth and develop premature branching. Even with pruning and tying, the wide spacing between plants prevents them from withstanding wind and excessive lateral branch growth, preventing them from developing a straight, perfectly straight trunk. This not only affects the Langya elm's aesthetic appearance but also its potential for growth. The above treatments produce seedlings with straight trunks, beautiful shapes, and a high survival rate.

[0006] Preferably, in step (1), excellent plants aged 20 to 50 years are selected for seed collection, and yellow-winged fruits are taken. The seeds are soaked in warm water at 30 to 40°C for 12 to 24 hours, dried in a ventilated place, and then sown.

[0007] Preferably, in step (1), the seeding is carried out by row sowing, the seedbed is 1.0-1.5 m wide, the bed surface is 10-20 cm higher than the walkway, shallow trenches are dug on the surface of the seedbed, the depth of the trenches is controlled to be 2-3 cm, and the spacing between the trenches is controlled to be between 20-30 cm. The seeds are sown in the trenches and covered with soil after sowing.

[0008] Preferably, the root interruption treatment in step (1) is to cut off the main root at about 8-10 cm below the middle of the main root.

[0009] Preferably, after the roots are cut off in step (2), the main root length is retained at 20 to 30 cm, and the seedlings are dipped in mud before the second transplanting to improve the survival rate.

[0010] Preferably, in step (2), for seedlings with a diameter of less than 2 cm, the bare-root transplanting method is adopted; for seedlings with a diameter of more than 2 cm, the transplanting method with a soil ball is adopted, and the diameter of the soil ball is 8 to 10 times the diameter of the plant at breast height.

[0011] Preferably, after transplanting in step (2), the full height of the seedlings with obvious main trunks is retained, and the top trunk of the seedlings with obvious branches at the top of the main trunk is cut off, leaving only 1 / 2-2 / 3 of the seedling height, and only one main trunk is retained.

[0012] Preferably, the diameter of the soil ball in step (3) is 8 to 10 times the diameter at breast height of the plant.

[0013] Preferably, during the propagation and cultivation process, the first pruning is carried out in the winter of the second year after the second transplanting, and another pruning is carried out two years later, with the intensity of 1 / 3 to 1 / 2 of the tree height.

[0014] Beneficial effects of the present invention: Langya elm is a deciduous tree of the Ulmaceae family, endemic to China. It is found only in Langya Mountain in Anhui Province and Baohua Mountain in Jiangsu Province, growing in deciduous broad-leaved forests on limestone hills at altitudes of 100 to 250 meters. Langya elm is listed as a Class III endangered species under national protection and is on the verge of extinction. Intensified research on Langya elm cultivation techniques is crucial to ensure the long-term, sustainable utilization of this resource. The Langya elm breeding and afforestation seedling cultivation methods provided herein help improve seed germination efficiency and seedling survival rates, resulting in afforestation seedlings with straight trunks, beautiful shapes, and high survival rates. DETAILED DESCRIPTION

[0015] The present invention is further illustrated by the following examples, but is not intended to limit the present invention. The following provides specific materials and their sources used in the embodiments of the present invention. However, it should be understood that these are merely exemplary and are not intended to limit the present invention. The cultivation methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0016] Example 1: Seedling cultivation (1) Sowing Seeds are collected from high-quality plants aged 20 to 50 years with symmetrical crowns, lush foliage, straight trunks, and robust growth. Langya elm seeds mature between April and May. Select yellowing winged fruits and soak the seeds in warm water at 30-40°C for 12-24 hours. Remove the seeds, place them in a well-ventilated area indoors, and spread them out to dry. Sow the soaked seeds immediately using row sowing. The seedbed should be 1.0-1.5 meters wide and 10-20 cm above the walkway. Dig shallow trenches 2-3 cm deep and 20-30 cm apart. Sow between 60 and 100 seeds in each trench. After sowing, cover the seeds with soil, ensuring that the seeds are not visible and avoiding excessive soil coverage. After the soil is covered, compact it appropriately and water the seedbed thoroughly with a fine-meshed watering can. Cover the surface with plastic film or straw and compact the plastic film with bricks. A shade net can be built above.

[0017] (2) Seedling management About 7 days after sowing, some seeds begin to germinate. Remove the straw covering three times depending on weather conditions. If the light intensity is too high after uncovering, the young seedlings will be easily burned. A single layer of sunshade net can be built over the seedlings. In early July and early August, apply 37.5 and 75.0 kg / hm2 of urea, respectively. 2 , adopt the furrow fertilization method, and cover the soil immediately after fertilization to prevent fertilizer nutrient loss. If the field is dry, water it in time to ensure that the soil moisture is appropriate.

[0018] Promptly remove seedlings that are overcrowded, underdeveloped, injured, or infected with pests and diseases. Thin out the seedlings for the first time one month after they emerge. Thin out and transplant seedlings for the second or third time based on their growth. The number of plants retained per unit area should be approximately 15% more than the planned seedling yield.

[0019] First transplanting of the seedlings: After the Langya elm seedlings have two pairs of true leaves, they are thinned and transplanted. Thinning is to remove weak seedlings and overcrowded seedlings, while transplanting is to replant in plots where no seedlings have emerged. Both processes are used to adjust the spacing between seedlings in rows and plants. During transplanting, the root tips are pinched to promote lateral root growth. When the seedlings reach a height of about 5 cm, they are transplanted, and the spacing between rows and plants is controlled at 4-6 cm x 20-30 cm.

[0020] In order to encourage the seedlings to grow lateral roots as quickly as possible, for seedlings that have not been transplanted during the thinning and transplanting process, when they grow to 30-40 cm in height, the main root is shoveled off about 8 cm from the middle and lower part of the main root. After comparison, the root system of the seedlings treated with root cutting is well-developed, the number of lateral roots and fibrous roots is more, and the survival rate of the seedlings is improved. The main roots of the seedlings that have not been treated with taproot cutting grow thick and long, and the lateral roots are underdeveloped and the number is small, which has a great impact on their survival rate after afforestation. Through observation of the Langya elm seedlings that died after afforestation, the seedlings without root cutting accounted for more than 95%. Therefore, root cutting plays a very important role in improving the survival rate of Langya elm. It can properly control the excessive growth of the main root and promote the growth of lateral roots.

[0021] Seedling pest and disease control: 1) Physical prevention Pests that are caught and trapped can be controlled by artificial means and methods such as light, electricity, and heat.

[0022] 2) Chemical control The main insect pest during the Langya elm seedling stage is the autumn four-veined aphid. In Chuzhou City, this pest produces multiple generations a year and often overwinters as eggs in cracks in elm branches. For prevention and control, remove galls from seedlings as soon as they first appear, prune overgrown branches and overcrowded branches within the trunk, and improve light transmission in the forest. A 1500-fold dilution of 2%-3% cypermethrin or a 2000-fold dilution of 10% imidacloprid can be used for control. For other leaf-feeding pests, spray a 1500-fold dilution of 2.5% cypermethrin.

[0023] Fertilizer management during the seedling stage: Adhere to the principle of using organic fertilizer as the main fertilizer, chemical fertilizer as the auxiliary fertilizer, applying sufficient base fertilizer and appropriate topdressing. The base fertilizer is mainly organic fertilizer, and the amount of phosphorus fertilizer is 3000kg / hm 2 , compound fertilizer 450~750kg / hm 2 Combined with tillage, apply evenly into the deep soil layer. For seed fertilizer, apply a granular fertilizer primarily containing phosphorus, mix evenly with the seeds, or soak the seeds in a dilute solution of trace elements. Seeds that have been germinated should not be mixed with seed fertilizer; instead, the seed fertilizer should be applied to the sowing furrow first. Topdressing should primarily be urea. Apply the first topdressing when the seedlings have all emerged, and the second and third topdressings should be applied in June and July during the rapid growth period. The dosage should not exceed 150 kg / hm2. 2 .

[0024] Example 2 Afforestation seedling cultivation 1. Planting 1) Seedling selection and processing The seedlings selected are 2-3 year old strong seedlings, designed according to the standard of Class I seedlings, striving to have complete root system, straight stems, full lignification; well-developed main roots, many lateral roots or fibrous roots; well-developed, free from diseases and pests, and no mechanical damage.

[0025] Before planting, the roots of the seedlings should be shortened to keep the main root length at 20-30cm, and all side branches should be removed. When transplanting, the seedlings should be dipped in mud to improve the survival rate.

[0026] 2) Planting method ① Bare-root transplanting: For Langya elm plants with a diameter of less than 2cm, bare-root transplanting (with a small amount of perennial soil) is recommended. It is best to plant them immediately after planting. Before planting, prune any damaged, dead, or overgrown roots, ensuring the cut ends are smooth.

[0027] ② Transplanting with a soil ball: Oversized seedlings (over 2cm in diameter) must be transplanted with a soil ball. The diameter of the soil ball should generally be 8-10 times the tree's diameter at breast height. After the soil ball is formed, wrap it with straw rope. The rope does not need to be removed when the seedling is planted.

[0028] Plant the seedlings at a moderate depth, about 5 cm from the root trace, and press firmly to keep the seedlings upright and the roots stretched out. After planting, water them promptly to allow them to take root and build up the soil into a bun shape. Use a tripod to secure the tree.

[0029] 3) Reasonable density planting and two transplanting Langya elm is cultivated as a timber forest. In the early stage, dense planting is adopted to make the trunk grow upright and cultivate the tree shape. The initial planting density is 3300-25000 plants / hm2. 2 , the spacing between rows and plants can be maintained at 1m*1m-1m*2m. After growing for 1-2 years after canopy closure, transplant again, and the spacing between rows and plants can be 2m*3m. After multiple transplants until canopy closure again, the trunk of Langya elm can reach about 4m, so that the trunk is basically formed. In the later stage, appropriate thinning can be carried out according to needs to cultivate high-quality large seedlings. In terms of forest stand structure, pure Langya elm forest can be selected, or mixed forests can be appropriately created. Various models such as Langya elm × thin-shelled pecan, Langya elm × pine mixed forest can be created to reduce the harm of pests and diseases and maintain ecological balance. Multiple transplanting is very important for the cultivation of Langya elm. The first transplanting in the seedling stage can promote the growth of lateral roots, the second transplanting can promote the straightening of the trunk, and the third transplanting can promote the formation of the crown. Reforestation after three transplants in the seedling stage can achieve twice the result with half the effort.

[0030] 2. Seedling care and management For the first three years after transplanting, loosen the soil and weed every spring, summer, and autumn. The depth is generally 5 cm. Deepen the weeds appropriately in arid areas. In hilly and mountainous areas, expand the holes in conjunction with tending to increase the nutrient area. Expand the weeds annually until the stand is fully closed. Closedness is generally achieved by the third year. Prune the first branch in the winter of the second year to 1 / 3 to 1 / 2 the tree's height. For multi-headed seedlings, retain only one main trunk. Prune again two years later. Ensure smooth cuts that do not damage the bark or leave stumps. Bud removal is typically performed in May, followed by appropriate summer pruning in August.

[0031] 3. Forestry and agricultural intercropping Between afforestation and stand closure, appropriate intercropping can be carried out according to the afforestation density. For example, intercropping can include low-stalk crops such as peanuts, beans, rapeseed, chrysanthemums, and Chinese medicinal herbs. Tall or climbing crops should not be intercropped.

Claims

1. A method for breeding and afforestation seedlings of Langya elm, characterized in that: The steps include: (1) Take mature seeds of Langya elm and sow them. When the seedlings have two pairs of true leaves and the height reaches 5 cm, transplant them for the first time. Pinch off the root tips during transplanting. Keep the spacing between seedlings at 4-6 cm × 20-30 cm after transplanting. For seedlings that are not transplanted and left in the bed, cut off the main roots when they grow to 30-40 cm in height. (2) Select 2-3 year old strong seedlings for the second transplant. Cut off the roots and remove all side branches before transplanting. The transplanting row spacing is 1-1.5m*1-1.5m; (3) After the trees have grown for 1-2 years after becoming densely populated, they are transplanted for the third time with a row spacing of 2-3m*2-3m. The trees are transplanted with the soil ball and the exposed roots outside the soil ball are cut off.

2. The method for breeding and cultivating afforestation seedlings according to claim 1, characterized in that: In step (1), select high-quality plants aged 20 to 50 years to collect seeds, take yellow-winged fruits, soak the seeds in warm water at 30 to 40°C for 12 to 24 hours, dry them in a ventilated place, and then sow them.

3. The method for breeding and cultivating afforestation seedlings according to claim 2, characterized in that: In step (1), the seeding is carried out by row sowing. The width of the seedbed is 1.0-1.5 m, and the bed surface is 10-20 cm higher than the walkway. Shallow trenches are dug on the surface of the seedbed. The depth of the trenches is controlled to be 2-3 cm, and the spacing between the trenches is controlled to be between 20-30 cm. The seeds are sown in the trenches and covered with soil after sowing.

4. The method for breeding and cultivating afforestation seedlings according to claim 1, wherein: Step (1) The root interruption treatment is to cut off the main root at about 8-10 cm below the middle of the main root.

5. The method for breeding and cultivating afforestation seedlings according to claim 1, characterized in that: After the roots are cut off in step (2), the main root length is retained at 20-30 cm, and the seedlings are dipped in mud before the second transplanting to improve the survival rate.

6. The method for breeding and cultivating afforestation seedlings according to claim 5, characterized in that: In step (2), for seedlings with a diameter of less than 2 cm, the bare-root transplant method is adopted; for seedlings with a diameter of more than 2 cm, the transplant method with a soil ball is adopted, and the diameter of the soil ball is 8 to 10 times the diameter of the plant at breast height.

7. The method for breeding and cultivating afforestation seedlings according to claim 5, characterized in that: After transplanting in step (2), the seedlings with obvious main trunks are kept at their full height. For seedlings with obvious branches at the top of the main trunk, the top trunk is cut off, leaving only 1 / 2-2 / 3 of the seedling height, and only one main trunk is retained.

8. The method for breeding and cultivating afforestation seedlings according to claim 1, characterized in that: In step (3), the diameter of the soil ball is 8 to 10 times the diameter of the plant at breast height.

9. The method for breeding and cultivating afforestation seedlings according to claim 1, characterized in that: During the propagation and cultivation process, the first pruning should be done in the winter of the second year after the second transplanting, and another pruning should be done two years later, with the intensity of 1 / 3 to 1 / 2 of the tree height.