A method for grafting magnolia grandiflora onto magnolia denudata

Abstract

The application discloses a method for grafting magnolia denudata with magnolia grandiflora, and belongs to the technical field of plant grafting and maintenance. The method for grafting magnolia denudata with magnolia grandiflora is characterized by using magnolia denudata as a stock, using a branch of magnolia grandiflora as a scion, adopting the bud-embedding grafting method, and combining with field water and fertilizer management in the later period to obtain the grafted plant. In the second year after grafting, a special spraying agent for magnolia grandiflora is sprayed. The grafting method is simple in process, and the survival rate of grafting is above 70% by selecting a suitable magnolia denudata stock, a suitable magnolia grandiflora scion, a suitable grafting time and a correct grafting mode, so that the propagation efficiency of magnolia grandiflora seedlings is greatly improved, and large-scale seedling raising of magnolia grandiflora can be realized, with low cost and high benefit. After the spraying agent is used, the number of flowers and the quality of flowers of magnolia grandiflora can be effectively improved, the spraying agent is convenient to use, is mild and safe, and the flowering ornamental property of magnolia grandiflora is improved.

Description

Technical Field

[0001] This invention relates to the field of plant grafting and maintenance technology, and more specifically to a method for grafting Magnolia denudata onto Magnolia 'Baohua'. Background Technology

[0002] Magnolia zenii (WCCheng) DLFu is a deciduous tree belonging to the genus Magnolia in the family Magnoliaceae. It is endemic to Baohua Mountain in Jurong, Jiangsu Province, growing in broad-leaved forests and bamboo forests on mountain slopes at an altitude of approximately 220 meters. Magnolia zenii has a straight trunk, dense foliage, and blooms before the leaves appear in February and March. The petals are white on the inside, white on the upper part of the outside, and pale purplish-red on the lower part. The flowers are large, fragrant, and beautiful, making it a highly prized ornamental tree.

[0003] Due to its high scientific research value and scarcity in the wild, *Magnolia baohuaensis* was listed as a Class II National Key Protected Wild Plant in 1999 and 2021, respectively. It was also listed in the 1991 *China Plant Red Data Book*, the 2004 *China Species Red List*, the 2013 *China Biodiversity Red List - Higher Plants* (Critically Endangered), the 2011-2015 *National Project for the Rescue and Conservation of Wild Plants with Extremely Small Populations*, and in the 2023 IUCN Red List of Threatened Species (CR). According to field surveys conducted annually by relevant domestic research institutes and the Jiangsu Provincial Wildlife Conservation Station, there are currently only 118 wild adult *Magnolia baohuaensis* individuals remaining in the Baohuashan Nature Reserve.

[0004] Currently, sexual reproduction of Magnolia baohua is usually achieved through seed sowing, while asexual reproduction primarily uses methods such as cuttings. However, seed sowing suffers from limited seed resources, and the seeds, with their bright red aril rich in oil, are easily consumed by birds and rodents in the forest. Furthermore, the seeds of Magnolia baohua are encased in a fleshy outer seed coat, making them difficult to separate, and the fruit ripening period is short; early harvesting results in immature seeds, while late harvesting leads to seed drop, resulting in a germination rate of only 3-40% for most sowing methods. Additionally, the natural pollination and fruit setting of sexual reproduction methods can easily lead to phenotypic variations in offspring, hindering the large-scale breeding and propagation of Magnolia baohua. Propagation of Magnolia baohua through cuttings results in low rooting and survival rates, leading to high costs for large-scale breeding and hindering its widespread adoption.

[0005] Therefore, providing a method for grafting Magnolia denudata onto Magnolia 'Baohua' is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for grafting Magnolia denudata onto Magnolia basilica, which has a high survival rate, is simple, and is easy to operate in practice.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for grafting Magnolia denudata onto Magnolia 'Baohua', the specific steps are as follows:

[0009] (1) Select two-year-old Magnolia denudata with a ground diameter of 0.9-1.5cm as rootstock to ensure that the plant is healthy and free from pests and diseases;

[0010] (2) In mid-March or late September, select healthy branches with a diameter of 0.5-1.0 cm from the outer edge of the crown of the mother tree of Magnolia baohua before the spring sap flow or after the tree stops growing in autumn as scions;

[0011] (3) In mid-March or late September, use the Magnolia denudata from step (1) as the rootstock and the Magnolia basilica from step (2) as the scion for grafting using the inlay bud grafting method.

[0012] (4) After grafting, promptly remove any sprouts on the rootstock and keep only the scion;

[0013] (5) Water once every 3 days within 30 days after grafting; after 30 days, water once every 4-6 days and loosen the soil in time to retain moisture; reduce or stop watering on rainy days in summer or when the temperature is low in winter.

[0014] (6) After 3-5 weeks of spring grafting and 21-24 weeks of autumn grafting, when the scion buds swell, sprout branches and unfold leaves, gradually loosen the binding; set up a support to prevent the graft union from tearing and falling off.

[0015] (7) After weeding, apply nitrogen, phosphorus, and potassium compound fertilizer once in late May or mid-April of the following year after autumn grafting, using root fertilization, with a total application rate of 30-45 kg / hm. 2 Apply NPK compound fertilizer in late July, applying it to the roots, with a total application rate of 50-75 kg / hm². 2 The nitrogen, phosphorus, and potassium ratio of the nitrogen-phosphorus-potassium compound fertilizer is 15:15:15.

[0016] In step (4), when combining field management such as watering, the sprouts on the rootstock should be removed in time to prevent the loss of nutrients in the rootstock and affect the survival rate of the scion.

[0017] Furthermore, in step (3), the grafting method is as follows: when the buds of the Magnolia officinalis rootstock have not yet begun to swell and the sap has begun to flow in spring, choose a sunny day for grafting, remove excess buds at the top and base of the Magnolia officinalis scion, and select branches with 1-2 axillary buds in the middle for grafting; at a distance of 5-10cm from the base of the rootstock, use the 15° oblique cut bud grafting method, wrap and seal the interface with grafting tape, and cut off excess branches above the grafting point of the rootstock.

[0018] Further, in step (3), the grafting method is as follows: after the white magnolia rootstock tree stops growing in autumn, remove the leaves, choose a sunny day for grafting, remove the excess buds at the top and base of the scion, select branches with 1-2 axillary buds in the middle for grafting, cut off the leaves and leave the petioles; at a distance of 5-10cm from the base of the rootstock, use the 15° oblique cut bud grafting method, wrap and seal the interface with grafting tape, after overwintering, at the end of March of the second year, when the scion buds begin to sprout and swell, cut off the excess branches above the scion of the rootstock.

[0019] Furthermore, a special spraying agent for Magnolia baohua, by weight, is prepared in 1000 parts by containing 5-6 parts surfactant, 0.5 parts ferrous sulfate, 6-8 parts potassium dihydrogen phosphate, 0.5-1 parts 6-benzyladenine, and 4-6 parts urea, with the remainder being water.

[0020] Furthermore, the surfactant is rhamnolipid (Ruis, Xi'an Ruijie Biotechnology Co., Ltd.), sophorolipid (Yousuo, Shandong Yousuo Chemical Technology Co., Ltd.), or trehalolipid (Sinok, Guangzhou Sinoco Biotechnology Co., Ltd.).

[0021] Furthermore, the aforementioned special spraying agent for Magnolia baohua, when prepared in 1000 parts by weight, contains 5 parts rhamnolipid, 0.5 parts ferrous sulfate, 6 parts potassium dihydrogen phosphate, 0.5 parts 6-benzyladenine, and 4 parts urea, with the remainder being water.

[0022] Furthermore, the specific steps for preparing the special spray agent for Magnolia baohua are as follows:

[0023] (1) Dissolve the surfactant in 200-350 parts of water and refrigerate for later use;

[0024] (2) Weigh out ferrous sulfate and potassium dihydrogen phosphate, add 100-150 parts of water to dissolve, mix well and set aside;

[0025] (3) Mix the solutions prepared in steps (1) and (2), then add 6-benzyladenine and urea and mix them together, and bring the volume to 1000 parts to obtain a special spraying agent.

[0026] Furthermore, the method of using the special spray for Magnolia baohua is as follows: starting 3 months before flowering, spray the surface of the branches and buds of Magnolia baohua once a month for a total of 3 times. Apply 50-100ml of the spray to the surface of each plant to ensure that the plant fully absorbs the spray.

[0027] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for grafting Magnolia denudata onto Magnolia 'Baohua', which has the following beneficial effects:

[0028] (1) High survival rate: By selecting appropriate lignification degree Magnolia baohua branches, choosing suitable Magnolia white as rootstock, and adopting appropriate grafting time and grafting method, the survival rate can reach more than 70%.

[0029] (2) Low cost and wide availability of materials: The branches of Magnolia baohua used for grafting can be obtained in large quantities from the scion nursery. The market price of Magnolia baiyu seedlings is low and the quantity is large, making them easy to obtain. Large-scale grafting can obtain a large number of seedlings.

[0030] (3) Maintaining the stability of Magnolia baohua germplasm: The present invention adopts a grafting method, which can maintain the genetic stability of Magnolia baohua germplasm from the same scion source, which is conducive to the maintenance of excellent traits and will not result in germplasm degeneration in sexually reproduced offspring.

[0031] (4) High-quality rootstock expands the application range: The rootstock used in this invention is white magnolia (Yulania denudata (Desr.) DLFu). This species has good adaptability and is widely planted in most provinces of my country and grows normally. Therefore, grafting white magnolia onto Baohua magnolia can expand the planting area of ​​Baohua magnolia, a rare and endangered plant, in other provinces of my country and improve the stress resistance and adaptability of Baohua magnolia.

[0032] Baohua Magnolia Special Sprayer has the following advantages:

[0033] (1) By adding surfactants, a waxy layer is formed on the surface of branches and buds, which can protect the Magnolia baohua during the low temperature period in winter. At the same time, surfactants can also act as humectants, allowing other effective substances to spread fully and promoting absorption and utilization.

[0034] (2) Potassium dihydrogen phosphate in the spray is a high-quality and efficient phosphorus and potassium fertilizer that can promote the differentiation of flower buds in plants, promote the transformation of plants to sexual reproduction, and make flower buds swell, flower buds become large and flowers become strong during the flowering period; at the same time, it can also improve the ability of roots to absorb nutrients.

[0035] (3) Urea is a recognized neutral and fast-acting fertilizer. When applied during the flower bud differentiation period, it can increase the absorption of nitrogen by Magnolia baohua, accelerate the development of its root system, and accumulate nutrients for flowering.

[0036] (4) 6-Benzyladenine in the spray is a plant growth regulator. Its main function in this spray is to break plant dormancy and promote the formation of flower buds and flowering.

[0037] (5) The special spray for Magnolia baohua, combined with the quick-acting fertilizer and nitrogen-phosphorus-potassium compound fertilizer applied after grafting, can produce strong grafted seedlings in Magnolia baohua seedling production. It can also shorten the flowering period of Magnolia baohua after grafting, increase the number of flower buds and improve the quality of flowering. It provides efficient and effective technology for the selection, propagation and improvement of excellent individual plants of Magnolia baohua and the enhancement of its landscaping value. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 The attached figure shows a demonstration of the grafting operation of Magnolia grandiflora according to the present invention;

[0040] Figure 2 The attached image shows the flower buds of this invention swelling and ready to open;

[0041] Figure 3 The attached image shows the fully open flower of the Magnolia baohua of this invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] On March 15, 2022, researchers performed grafting at Nanjing Zhongshan Botanical Garden. Figure 1Select a two-year-old Magnolia denudata rootstock with a ground diameter of 0.9cm as the rootstock, ensuring the plant is robust and free from pests and diseases. Collect Magnolia buds with a branch thickness of 0.5cm as scions. In spring, before the buds of the Magnolia denudata rootstock begin to swell and sap begins to flow, graft on a sunny day. Remove excess buds from the top and base of the Magnolia bud, selecting branches with 1-2 axillary buds in the middle for grafting. Use a 15° oblique bud grafting method, grafting 8cm above the ground on the rootstock, promptly removing any sprouts from the rootstock, retaining only the scion. Water every 3 days for the first month after grafting, then every 5 days until late May. Grafting should be gradually loosened 35 days after grafting, once the scion buds begin to swell. Two months after grafting, apply a compound fertilizer (NPK ratio 15:15:15) at a rate of 35kg / hm². 2 Apply fertilizer to the roots; four months after grafting, apply a compound fertilizer of nitrogen, phosphorus, and potassium once, at a rate of 55 kg / hm². 2 .

[0045] On December 5, 2022, 5g of rhamnolipin was weighed and dissolved in 200g of water, then refrigerated for later use. 0.5g of ferrous sulfate and 6g of potassium dihydrogen phosphate were weighed and dissolved in 100g of water. The solutions were mixed, and then 0.5g of 6-benzyladenine and 4g of urea were added. Water was added to make up the volume to obtain 1000g of the special spray. The spray was applied once a month, with 50ml applied to each plant surface each time, for a total of three applications, ending before flowering in March 2023.

[0046] The grafting survival rate reached 72%, and the flowering rate of Magnolia baohuaensis reached 55% in the spring of 2023.

[0047] Figure 2 Flower buds are swelling and awaiting opening; Figure 3 The fully open flowers of the Magnolia denudata.

[0048] Example 2

[0049] On September 23, 2022, researchers grafted Magnolia baohua onto Magnolia denudata at the Nanjing Zhongshan Botanical Garden nursery. Two-year-old Magnolia denudata with a ground diameter of 1.5 cm were selected as rootstock, ensuring the plants were robust and free from pests and diseases. Branches of Magnolia baohua with a diameter of 1 cm were collected as scions. After the rootstock stopped growing in autumn, the leaves were removed, and grafting was performed on a sunny day. Excess buds at the top and base of the scion were removed, and 1-2 axillary buds from the middle section were selected for grafting. Leaves were removed, leaving only the petioles. Grafting was performed at a 15° angled budding method, 10 cm above the ground on the rootstock. Any sprouts on the rootstock were promptly removed, leaving only the scion. For the first month after grafting, water was applied every 3 days, then every 5 days for two months. In February of the following year, the binding was gradually loosened. Apply NPK compound fertilizer (N:P:K ratio 15:15:15) once after April 20, 2023, via root application, at a rate of 40 kg / hm². 2 On July 20, 2023, apply nitrogen, phosphorus, and potassium compound fertilizer once, using root fertilization at a rate of 60 kg / hm². 2 .

[0050] On January 30, 2023, 6g of trehalose was weighed and dissolved in 350g of water, then refrigerated for later use. 0.5g of ferrous sulfate and 8g of potassium dihydrogen phosphate were weighed and dissolved in 150g of water. The solutions were mixed, and then 1g of 6-benzyladenine and 6g of urea were added. Water was added to make up the volume to obtain 1000g of the special spray. The spray was applied once a month, with 100ml applied to each plant surface each time, for a total of three applications, ending before flowering in March 2023.

[0051] The grafting survival rate reached 74%, and the flowering rate of Magnolia baohuaensis reached 58% in the spring of 2023.

[0052] Example 3

[0053] On March 18, 2022, researchers performed grafting of *Magnolia denudata* onto *Magnolia baohuaensis* at the nursery of Nanjing Zhongshan Botanical Garden. Healthy, disease-free, two-year-old *Magnolia denudata* plants with a ground diameter of 1 cm were selected as rootstock. *Magnolia baohuaensis* branches with a diameter of 0.8 cm were used as scions. Grafting was performed on a sunny day in spring, before the buds on the rootstock began to swell and sap flow started. Excess buds at the top and base of the *Magnolia baohuaensis* scion were removed, and 1-2 axillary buds in the middle section were selected for grafting. The graft was performed at a 15° oblique budding method, 5 cm above the ground on the rootstock. Any sprouts on the rootstock were promptly removed, leaving only the scion. Watering was carried out every 3 days until mid-April, and every 6 days in May. One month after grafting, when the scion buds began to swell, the binding was gradually loosened, and a support was used if necessary to prevent tearing of the graft union. Apply NPK compound fertilizer (N:P:K ratio 15:15:15) once on May 29th after grafting, applying it to the roots at a rate of 30 kg / hm². 2Apply NPK compound fertilizer once on July 24th, applying it to the roots, with a total application rate of 60 kg / hm². 2 .

[0054] On December 5, 2022, 5.5g of sophorolipid was weighed and dissolved in 200g of water, then refrigerated for later use. 0.5g of ferrous sulfate and 7g of potassium dihydrogen phosphate were weighed and dissolved in 100g of water. The solutions were mixed, and then 1g of 6-benzyladenine and 5g of urea were added. Water was added to make up the volume to obtain 1000g of the special spray. The spray was applied once a month, with approximately 70ml applied to each plant surface each time, for a total of three applications, ending in early March 2023 before flowering.

[0055] The grafting survival rate reached 70%, and the flowering rate of Baohua Magnolia in the spring of 2023 was 50%.

[0056] Comparative Example 1

[0057] On September 23, 2022, researchers conducted a comparative study on grafting Magnolia denudata onto Magnolia 'Baohua' at the Nanjing Zhongshan Botanical Garden nursery. Magnolia denudata with a ground diameter of 2.5 cm was selected as rootstock, ensuring the plants were robust and free from pests and diseases. Branches of Magnolia 'Baohua' with a diameter of 0.5 cm were collected as scions. After the rootstock stopped growing in autumn, the leaves were removed, and grafting was performed on a sunny day. Excess buds at the top and base of the scion were removed, and 1-2 axillary buds from the middle section were selected for grafting. Leaves were removed, leaving only the petioles. Grafting was performed at a point 10 cm above the ground on the rootstock using a branch grafting technique. Any sprouts on the rootstock were promptly removed, leaving only the scion. Watering was done every 3 days for the first month after grafting, then once a week for two months. The binding was gradually loosened 45 days after grafting.

[0058] Grafting by cuttings was unsuccessful; none of the scions survived.

[0059] Comparative Example 2

[0060] On September 23, 2022, researchers grafted Magnolia baohua onto Magnolia denudata at the Nanjing Zhongshan Botanical Garden nursery. Magnolia denudata with a diameter at 1.5 cm was selected as rootstock, ensuring the plant was robust and free from pests and diseases. Branches of Magnolia baohua with a diameter of 1 cm were collected as scions. After the rootstock stopped growing in autumn, the leaves were removed, and grafting was performed on a sunny day. Excess buds at the top and base of the scion were removed, and 1-2 axillary buds from the middle section were selected for grafting. Leaves were removed, leaving only the petioles. Grafting was performed at a 15° angled budding method, 10 cm above the ground on the rootstock. Any sprouts on the rootstock were promptly removed, leaving only the scion. For the first month after grafting, water was applied every 3 days, then weekly for two months. The binding was gradually loosened 45 days after grafting. Apply a quick-acting nitrogen, phosphorus, and potassium fertilizer (nitrogen, phosphorus, and potassium ratio 15:15:15) once after November 20, 2022, by root application; the application rate is 30 kg / hm². 2On January 20, 2023, apply nitrogen, phosphorus, and potassium compound fertilizer once, using root fertilization, with a total application rate of 50 kg / hm². 2 .

[0061] On January 30, 2023, weigh out 1 part trehalose and dissolve it in 350 parts water. Refrigerate for later use. Weigh out 0.5 parts ferrous sulfate and 2 parts potassium dihydrogen phosphate and dissolve them in 150 parts water. Mix the above solutions and add water to make up to a final volume of 1000 parts spray. Spray once a month, using 100 ml per plant each time, for a total of three sprays, ending before flowering in March 2023.

[0062] The grafting success rate was 72%, and in the spring of 2023, only a portion of the Magnolia baohua bloomed, with a flowering rate of only 10%.

[0063] In summary, Examples 1, 2, and 3 showed high grafting success rates, averaging over 70%, with over 50% of the plants flowering in the spring of 2023. In Example 4, none of the scions survived, resulting in unsuccessful grafting. In Example 5, only 10% of the grafted Magnolia baohua bloomed in the spring of 2023, with the vast majority of scions only developing into vegetative branches.

[0064] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for grafting Magnolia denudata onto Magnolia 'Baohua', characterized in that, The specific steps are as follows: (1) Select two-year-old Magnolia denudata with a ground diameter of 0.9-1.5 cm as rootstock to ensure that the plant is healthy and free from pests and diseases; (2) In mid-March or late September, select healthy branches with a thickness of 0.5-1.0 cm from the outer edge of the crown of the mother tree of Magnolia baohua before the sap flow in spring or after the tree stops growing in autumn as scions; (3) In mid-March or late September, use the Magnolia officinalis from step (1) as rootstock and Magnolia basilica from step (2) as scion for grafting using the inlay bud grafting method. (4) After grafting, promptly remove any sprouts on the rootstock and keep only the scion; (5) Water once every 3 days within 30 days after grafting; after 30 days, water once every 4-6 days and loosen the soil in time to retain moisture; reduce or stop watering on rainy days in summer or when the temperature is low in winter. (6) After 3-5 weeks of spring grafting and 21-24 weeks of autumn grafting, when the scion buds swell, sprout branches and unfold leaves, gradually loosen the binding; set up a support to prevent the graft union from tearing and falling off. (7) In late May of the year following spring grafting or mid-April of the year following autumn grafting, apply nitrogen, phosphorus and potassium compound fertilizer once after weeding, applying it to the roots, with a total application of 30-45 kg / hm. 2 Apply NPK compound fertilizer in late July, applying it to the roots, with a total application rate of 50-75 kg / hm². 2 The nitrogen, phosphorus, and potassium ratio of the nitrogen-phosphorus-potassium compound fertilizer is 15:15:

15.

2. The method for grafting Magnolia denudata onto Magnolia 'Baohua' according to claim 1, characterized in that, In step (3), the grafting method is as follows: when the buds of the Magnolia officinalis rootstock have not yet begun to swell and the sap has begun to flow in spring, choose a sunny day for grafting, remove the excess buds at the top and base of the Magnolia officinalis scion, and select branches with 1-2 axillary buds in the middle for grafting; at a distance of 5-10 cm from the base of the rootstock, use the 15° oblique cut bud grafting method, wrap and seal the interface with grafting tape, and cut off the excess branches above the grafting point of the rootstock.

3. The method for grafting Magnolia denudata onto Magnolia 'Baohua' according to claim 1, characterized in that, In step (3), the grafting method is as follows: after the white magnolia rootstock tree stops growing in autumn, remove the leaves, choose a sunny day for grafting, remove the excess buds at the top and base of the scion, select branches with 1-2 axillary buds in the middle for grafting, cut off the leaves and leave the petioles; at a distance of 5-10 cm from the base of the rootstock, use the 15° oblique cut bud grafting method, wrap and seal the interface with grafting tape, and at the end of March of the second year after overwintering, when the scion buds begin to sprout and swell, cut off the excess branches above the scion of the rootstock.

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