Cyclobalanopsis gilgii grafted seedling cultivation method

Abstract

The cyclobalanopsis gilgii grafted seedling cultivation method comprises the following steps: (1) scion collection: collecting annual branches with bare leaf buds as scions before the leaf buds germinate, and enabling the diameter of the scions to be more than 3mm; 2) scion treatment: cutting off 50% of leaves on the scions, wrapping the scions with a wet towel, and then putting the scions into a self-sealing bag for sand storage or cold storage at the temperature of 4 DEG C; 3) grafting; and 4) management and protection. On the basis of summarizing many years of grafting experience of cyclobalanopsis glauca, the cyclobalanopsis glauca grafted seedling cultivation method taking scion picking time, scion selection, storage and transportation, scion making, stock cutting grafting, warm water and fertilizer management, tooth wiping and sprout removal and the like as the core is provided, the grafting survival rate reaches 86.67%, and the technical difficulty of cyclobalanopsis glauca grafting is effectively solved. The method is simple to operate and clear in technical key points, and can generate remarkable benefits when being popularized and applied in production.

Description

Technical Field

[0001] This invention belongs to the field of seedling cultivation technology, specifically relating to a method for cultivating grafted seedlings of Quercus glauca. Background Technology

[0002] Red-skinned oak ( Cyclobalanopsis gilva (Blume) Oerst. is a species of oak in the family Fagaceae. Cyclobalanopsis This evergreen tree species can reach up to 30 meters in height and 1 meter in diameter at breast height. It is naturally distributed in provinces such as Zhejiang, Fujian, Hunan, Jiangxi, Guangdong, and Guizhou, as well as Japan. The red oak (Quercus glauca) is a diffuse-porous or semi-diffuse-porous wood, reddish-brown or yellowish-brown in color, with excellent quality, mostly considered a precious hardwood, and is a superior material for furniture, flooring, decoration, and handicrafts. Its sapwood is yellowish-brown, and its heartwood is dark reddish-brown. It is hard, heavy, strong, and elastic; it has a beautiful grain, a luster, and a unique fragrance. It is resistant to insect infestation, fire, and moisture, and is one of the four famous woods of Jiangnan. Furthermore, due to its tall and straight tree shape and dense foliage, it is also an excellent tree species for afforestation and landscaping. Red oak grows relatively quickly, is highly adaptable, has a deep root system, strong root sprouting ability, can tolerate intermittent short-term waterlogging, has a long lifespan, and is less susceptible to pests and diseases. It can grow in mountainous areas at altitudes of 300-1500m, and grows best in neutral or slightly acidic loam soils. It is especially suitable for mixed planting with pine and fir.

[0003] Southern provinces such as Zhejiang, Jiangxi, Fujian, and Hunan prioritize the development of *Quercus variabilis* as a precious tree species, requiring the propagation of nearly ten million high-quality container seedlings of various sizes annually for the construction of valuable timber forests and ecological restoration of forests affected by pine wilt disease. This necessitates significant technical demands for improved varieties and cultivation methods. Research on the distribution, breeding, seedling cultivation, and population evolution of *Quercus variabilis* is increasing year by year. Regarding issues such as delayed seed germination and low germination rates in its seedlings, scholars have conducted research from multiple perspectives, including different storage conditions, different habitats and shading treatments, exogenous hormone treatments, and transcriptomic and proteomic approaches. In contrast, research on grafted seedling cultivation techniques for *Quercus variabilis* is significantly insufficient. Because *Quercus variabilis* buds early in spring and sprouts rapidly, scions often require cold storage. Springtime rainfall is abundant, time is limited, and the plant is susceptible to pathogens, resulting in low grafting survival rates. The purpose of this invention is to improve the grafting survival rate of *Quercus variabilis*, reduce production costs, increase the growth of grafted seedlings, shorten the seedling nursery time, and effectively solve the grafting technical problems of preserving clonal lines of young *Quercus variabilis* and establishing clonal seed orchards. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a method for cultivating grafted seedlings of Quercus glauca, specifically achieved through the following technical solution: A method for cultivating grafted seedlings of Quercus glauca includes the following steps: (1) Bud selection time Bud selection before leaf bud emergence, usually in mid-February to early March, higher temperature needs to be picked up. Zhejiang, Jiangxi, Hunan and other places generally in late February.

[0005] (2) Bud selection and preservation ①Bud selection: choose sunny, short internodes, and well-developed annual branches.

[0006] ②Bud selection site: choose top branches with leaves and leaf buds. The buds on the branches cannot be hidden buds, and must be exposed buds that can survive grafting.

[0007] ③Bud preservation: The collected bud is cut in half and wrapped with a wet towel to keep it moist. For short-term storage, the bud is packed in a self-sealing bag and stored in sand for at least 20 days. When the amount of bud is small, it can be stored in the refrigerator. The hidden buds on the red-barked oak bud do not grow, and the clustered buds at the top of the bud can be grafted but are difficult to survive, and the leaf buds are the best. Before preservation, cut off half of the leaves on the bud, mainly to avoid damage to the leaf buds during preservation. When transporting over long distances, the bud is placed in a foam box with an ice bag for cold chain transportation.

[0008] ④Requirements: The diameter of the bud is more than 3mm, the thicker the better. Under natural conditions, the red-barked oak is tall and difficult to collect the top bud, so try to collect thick buds from the middle and lower parts.

[0009] (3) Selection and treatment of rootstock ①Rootstock selection: The rootstock should be selected for healthy growth, well-developed root system, no pests and diseases, and compatibility with the scion. Two-year-old, 0.8cm or more in diameter, red-barked oak seedlings are the best for grafting.

[0010] ②Rootstock treatment: Cut the rootstock 5-8 cm from the ground and trim it flat, then cut it vertically with a cutting knife on the smooth side of the rootstock, with a length of 2-3 cm.

[0011] ③Requirements: The rootstock needs to retain an appropriate amount of leaves or small branches, and the main stem should retain 4-5 leaves or small branches with 4-5 leaves to ensure the growth of the rootstock and the scion after grafting.

[0012] (4) Scion preparation ①Cut the scion: cut the bud into a 5-10 cm long scion with 2 or more leaf buds.

[0013] ②Cutting grafting: use the cutting grafting knife to cut the base of the scion without buds, and cut a smooth long inclined plane of 2-3 cm long. Do not cut the pith, and it is better to have a little xylem. The other side is cut into a short inclined plane of less than 1 cm long, so that the lower end of the scion is a flat wedge. When the scion is about 3 mm thick, the length of the long and short inclined planes is about 2.5 cm and 1 cm respectively, and the thicker the scion, the larger the inclined planes.

[0014] ③Requirements: the cutting grafting knife should be sharp, and the hand should be steady to ensure that the cutting surface is smooth and flat, and it is best to cut it in one stroke.

[0015] (5) Grafting ①Grafting time: the best time is in early March, when the leaf buds of the sand-stored scion are dormant buds.

[0016] ②Specific operation: insert the long cutting surface of the scion into the cut of the stock with the inside, and align the two sides of the cambium. The upper end of the cutting surface of the scion is exposed by 0.1-0.3 cm, that is, "white", to facilitate the healing growth of the stock and the scion.

[0017] ③Requirements: one of the two leaf buds remaining on the scion during grafting is as close to the graft as possible. The leaf bud close to the graft is more likely to grow callus, promoting healing of the graft.

[0018] (6) Binding After grafting, use a plastic tape of 2 cm wide to bind the graft to prevent drying. Do not move the position of the cambium alignment of the stock and scion during binding, and the tightness should be moderate, neither damaging the tissue nor being firm.

[0019] (7) Later management ①Sheltered plastic tunnel for moisture retention and shade: the grafted seedlings need to be placed in a plastic tunnel for warmth and moisture retention and shade when the air temperature is low. After the scion bud germination and the new leaves unfold (the new branches of the scion grow to 5-10 cm), the tunnel is removed.

[0020] ②Check germination: observe the leaf bud germination of the grafted seedlings at any time. The leaf bud germination time is directly related to the air temperature, which will germinate immediately when the air temperature rises. The grafted seedlings with good healing of the graft and leaf bud germination indicate that they are basically alive.

[0021] ③Removing sprouts: when the leaf buds grow to 3-4 cm, the stock needs to be removed. Check after 2-3 weeks of grafting, and remove the sprouts from the base when the stock sprouts. Avoid pulling to avoid damaging the stock bark and scion. Removing sprouts is a continuous process, especially in the first few months after grafting, which needs to be checked regularly and treated in time. Timely and thorough removal of sprouts can ensure that nutrients are concentrated to supply the scion, promote rapid growth of the scion, and improve the survival rate of grafted seedlings and seedling quality.

[0022] (4) Water management: Immediately after grafting, water the soil to keep it moist, avoid water loss from the scion, and ensure that the soil and roots are in full contact to promote healing. Avoid direct flushing of the interface when watering to prevent the scion from loosening. Regularly water in the morning or evening (once every 5-7 days), and ensure good drainage by digging drainage ditches on both sides of the bed to prevent root rot. In summer and autumn, the high temperature season, the seedling needs more water, so the frequency of watering should be increased.

[0023] (5) Fertilizer management: After the new leaves of the scion unfold (about 1 month after grafting), apply a small amount of low-concentration nitrogen fertilizer (liquid application method: evenly irrigate the prepared nitrogen fertilizer solution around the roots of the seedling, ensuring that the soil is moist but not excessive, and avoiding water accumulation; low-concentration nitrogen fertilizer solution can be 0.2%-0.5% urea solution), to promote root development and new shoot growth.

[0024] (6) Out of the nursery. After the grafting seedling interface is completely healed, it can be transplanted, and the water and fertilizer management of the seedling bed is referred to until it is out of the nursery.

[0025] Based on the summary of the grafting experience of C. japonica 'Akaban', a grafting seedling cultivation method for C. japonica 'Akaban' is proposed, which takes the time of collecting scions, selection of scion strips, preservation and transportation, preparation of scions, grafting of the rootstock, warm water and fertilizer management, and toothpaste and sprout removal as the core. The grafting survival rate is 86.67%, effectively solving the technical difficulties of grafting C. japonica 'Akaban'. The method is simple to operate, the technical points are clear, and the application of the method in production can produce significant benefits. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the scion strip treated in Example 2; Figure 2 is the scion strip stored in the refrigerator; Figure 3 is the survived C. japonica 'Akaban' grafting seedling. DETAILED DESCRIPTION

[0027] The present application will be further described in conjunction with specific examples to better understand the technical solutions.

[0028] Example 1: C. japonica 'Akaban' grafting test Grafting is the most common way of artificial asexual reproduction, its principle is to make the cambium of the rootstock and the scion tightly combined, because of cell proliferation, they heal each other to form a whole, which is the principle of grafting. Grafting can maintain the excellent characteristics of the original variety, grow faster, and bloom earlier. The nutrients needed for the growth of the grafted plant generally come from the rootstock.

[0029] In early March 2021, a grafting experiment of Quercus aliena var. acutissima was carried out in Zhujiaibu forest region of Xin'anjiang Forest Farm in Jiande, Zhejiang Province. The effects of age of rootstock and grafting method on the survival rate of Quercus aliena var. acutissima were mainly studied. One-year-old branches of Quercus aliena var. acutissima in the nursery were collected as scions, and two-year-old and three-year-old seedlings of Quercus aliena var. acutissima were used as rootstocks. Two different grafting methods, i.e., cutting grafting and cleft grafting, were used for the grafting of the same rootstock. After grafting, the grafted seedlings were cultivated in the nursery according to the production management, and the survival conditions were recorded.

[0030] The experimental results showed that the age of rootstock and grafting method had a significant effect on the survival rate of Quercus aliena var. acutissima (Table 1). The average survival rate of cutting grafting was 76.67%, which was 21.05% higher than that of cleft grafting. The survival rate of two-year-old rootstock cutting grafting was 86.67%, which was 30.00% higher than that of three-year-old rootstock grafting. The survival rate of two-year-old rootstock cleft grafting was 76.67%, which was 53.34% higher than that of three-year-old rootstock grafting. Quercus aliena var. acutissima should be grafted with two-year-old rootstock and cutting grafting method.

[0031] Table 1 Effects of age of rootstock and grafting method on the survival rate of Quercus aliena var. acutissima

[0032] Example 2: Construction of Quercus aliena var. acutissima scion orchard Unlike other species of Quercus, Quercus aliena var. acutissima has the characteristics of few dormant buds, not full, early germination (starting in late February), and synchronous germination of most buds on branches. In Zhejiang Province, the scion strips of natural forest superior trees should be collected in early February, and in southern provinces such as Hunan and Fujian, the scion strips should be collected in early February. After the treatment of removing 50% of the leaves on the scion strips and cold storage, the scion strips are grafted with two-year-old container seedlings with a ground diameter of 0.8 cm or more by cutting grafting method in early March, as shown in Figures 1-2 The survival rate of grafted seedlings of Quercus aliena var. acutissima can reach 86.67%, and the annual shoot growth can reach 60-80 cm, as shown in Figure 3

[0033] Due to the early germination of dormant buds of Quercus aliena var. acutissima, a special scion orchard should be established to ensure the scale breeding of grafted container seedlings of Quercus aliena var. acutissima in the construction of the garden. In 2017, the project team selected superior tree resources with tall tree body, straight and full stem shape, narrow crown, fine branches, normal fruiting, and no disease and insect pests in the superior natural forest stand of Quercus aliena var. acutissima. In February 2019, the scion strips were collected, and in March of the same year, the two-year-old Quercus aliena var. acutissima container seedlings with a ground diameter of 0.8 cm or more were grafted with the scion strips of young trees by cutting grafting method in the Zhujiaibu nursery base in Jiande, Zhejiang Province. In March 2021, a 4 mu scion orchard was constructed in the National Key Forest Tree Variety Base in Jiande, Zhejiang Province, which provided grafted seedlings for solving the technical difficulties of asexual propagation of Quercus aliena var. acutissima.

[0034] Example 3: Construction of Quercus aliena var. acutissima clone seed orchard​ The Jiande red-bark Qinggang asexual line seed orchard built by the present application can produce seeds in 3 years, and was identified as a Zhejiang forest tree variety (ZheR-CSO(1)-CG-001-2023) in 2024. The seed orchard has the characteristics of preserving excellent genetic characteristics and original quality, early flowering and fruiting, dwarfing, and easy seed production management.

[0035] ① Selection of superior trees: In 2017, in the selected forest stands of red-bark Qinggang in the main distribution area, according to the proposed investigation method and standard, along a certain line, single trees meeting the requirements of tall height, large diameter, uniform crown, narrow crown width, straight trunk and fine branches were selected as candidate trees, and the candidate superior trees were selected by using the dominant tree comparison method. A total of 80 red-bark Qinggang superior trees were selected.

[0036] ② Collection and grafting preservation of superior tree bud strips: In February 2019, red-bark Qinggang superior tree bud strips were collected for cold storage preservation. In early March 2019, 2-year-old red-bark Qinggang seedlings with a ground diameter of more than 0.8 cm were used in the Zhujiaibu nursery base in Jiande City, and the method of cutting grafting was used to graft and preserve the superior tree bud strips.

[0037] ③ Construction of asexual line seed orchard: In March 2021, a red-bark Qinggang asexual line seed orchard was built in Shouchang Forest Farm in Jiande City. The seed orchard covers an area of 42 mu, with 46 asexual lines completely randomly arranged with a plant spacing of 6m x 6m. During the construction of the orchard, the distance between the same asexual lines was kept above 25m, and the distribution was as uniform as possible, while avoiding fixed matching between asexual lines to ensure full random pollination of each asexual line.

[0038] ④ Main economic indicators: The red-bark Qinggang asexual line superior tree seeds were used to cultivate light substrate net bag container seedlings in Qingyuan. The seedlings had high seed germination rate and grew well. The growth measurement results of the 1-year-old container seedlings showed that the container seedlings grew vigorously and fast, with an average height of 34.47 cm and an average ground diameter of 0.48 cm, which were higher than those of the container seedlings cultivated from the Jiangxi Shangrao natural forest mixed seed (control).

Claims

1. A method for cultivating grafted seedlings of Quercus glauca, characterized in that... The method comprises the following steps: 1) Bud taking: collecting one-year-old branches with exposed buds as scions before bud break, the diameter of the scions being more than 3 mm; 2) Scion treatment: wrapping the scions with a wet towel after cutting off 50% of the leaves, and then placing the scions in a self-sealing bag for cold storage or cold storage at a temperature of 4°C; 3) Grafting: 3-1) taking 2-year-old red-bark oak seedlings as rootstocks, cutting the rootstocks horizontally at a distance of 5-8 cm from the ground and retaining 4-5 leaves or retaining small branches with 4-5 leaves, and making a vertical incision on the smooth side of the rootstock to form a rootstock cut; 3-2) cutting the scions into 5-10 cm long scions with more than two leaf buds, and cutting the base of the scions into a long bevel and a short bevel; 3-3) inserting the long bevel of the scion into the rootstock cut with the long bevel facing inwards, aligning the cambium on both sides and exposing 0.1-0.3 cm, and binding the grafting site with a plastic bag; 4) Tube protection: 4-1) placing the grafted seedlings in a greenhouse for heat preservation, moisture retention and shade until the new shoots of the scions grow to 5-10 cm, and removing the greenhouse; 4-2) pruning the base of the rootstock when the buds grow to 3-4 cm to remove the sprouts; 4-3) applying a low-concentration nitrogen fertilizer after the new leaves of the scions unfold; 4-4) transplanting the grafted seedlings after the grafting site is completely healed.

2. The Quercus acutissima grafted seedling cultivation method according to claim 1, characterized in that, In step 1), the bud taking time is in the middle of February to early March.

3. The Quercus acutissima grafted seedling cultivation method according to claim 1, characterized in that, In step 3-1), the rootstock has a ground diameter of more than 0.8 cm, and the length of the cut is 2-3 cm.

4. The Quercus acutissima grafted seedling cultivation method according to claim 1, characterized in that, In step 3-2), the long bevel is 2-3 cm long, and the short bevel is less than 1 cm long.

5. The Quercus acutissima grafted seedling cultivation method according to claim 1, characterized in that, In step 3-3), during grafting, one of the leaf buds on the scion is ensured to be close to the grafting site.

6. The Quercus acutissima grafted seedling cultivation method according to claim 1, wherein In step 4-2), the removal of sprouts is performed by checking and removing the new sprouts of the rootstock every week.

7. The Quercus acutissima grafted seedling cultivation method according to claim 1, wherein In step 4-3), the low-concentration nitrogen fertilizer solution is a 0.2%-0.5% urea solution.

Images