A method for cultivating grafted kiwifruit seedlings with dual root systems

Abstract

This invention provides a method for cultivating grafted kiwifruit seedlings with two root systems, comprising the following steps: S1, Rootstock acquisition: Select one one-year-old *Actinidia cuspidatum* and one *Actinidia deliciosa* seedling as rootstocks, and prune the main roots of both rootstocks to a length of 10-15 cm, retaining 4-5 cm of stem; S2, Scion acquisition: Select branches of the *Actinidia deliciosa* variety as scions, with a length of 8-12 cm. Seal the upper end with wax or wound healing agent, and smooth the lower end with a flat cut; S3, Grafting: Using bark grafting or cleft grafting, graft the two rootstocks in opposite directions onto the lower end of the same scion, and wrap the grafting area with grafting film to form a grafted kiwifruit seedling. The grafted seedlings cultivated by this invention have two sets of root systems, one for *Actinidia cuspidatum* and one for *Actinidia deliciosa*, thus exhibiting strong resistance to waterlogging, drought, and pests and diseases, and absorbing nutrients comprehensively, resulting in high-quality and high-yield fruit with significant economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of kiwifruit cultivation technology, specifically relating to a method for cultivating grafted kiwifruit seedlings with dual root systems. Background Technology

[0002] Kiwifruit is one of the most difficult fruit tree species to cultivate, mainly because the traditional rootstock for kiwifruit is Actinidia chinensis, which has a low degree of root lignification, poor rooting ability, and serious defects such as intolerance to waterlogging, drought, and poor soil, as well as susceptibility to canker disease. Actinidia calyx, on the other hand, has a highly lignified root system with a dense structure, strong rooting ability, and is particularly tolerant of waterlogging and drought, as well as strong resistance to diseases and pests, making it an ideal rootstock. Utilizing the advantages of Actinidia calyx's root system to cultivate resistant seedlings plays an important role in solving the problems of drought, waterlogging, disease, and pests in kiwifruit cultivation and improving the adaptability of kiwifruit. However, due to the significant difference in stem thickening rates between Actinidia calyx and Actinidia chinensis and Actinidia chinensis var. sinica, the problem of uneven stem size easily arises, affecting the survival rate of grafted seedlings and consequently reducing orchard uniformity and yield.

[0003] Currently, there are many techniques for double-root grafting, but most of them utilize the high tolerance of different rootstocks to cultivate seedlings with strong drought, waterlogging, and disease and pest resistance. However, in addition to solving the problems of grafted seedling resistance and survival, more attention should be paid to the quality and yield of the grafted fruit, since high-quality and high-yield agricultural products are what people pursue. Although existing double-root grafting techniques for kiwifruit have solved the problems of poor compatibility at the grafting site of the scion and the death of the tree due to severe longitudinal cracking of the trunk caused by the large and small size of the grafted seedlings, they have not substantially addressed the issues of fruit quality and yield. Summary of the Invention

[0004] In view of this, the present invention provides a method for cultivating kiwifruit scions by grafting a double rootstock of calyx kiwifruit and delicious kiwifruit onto delicious kiwifruit scions, which results in a better survival rate of grafted seedlings, faster and stronger plant growth, and significant improvements in bud break rate, branching rate and fruit setting rate.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for cultivating grafted kiwifruit seedlings with dual root systems includes the following steps:

[0007] S1. Rootstock acquisition: Select one one-year-old seedling of Actinidia chinensis and Actinidia deliciosa as rootstock. Trim the main root of the two rootstocks to a length of 10-15cm and retain 4-5cm of stem.

[0008] S2. Scion acquisition: Select branches of the delicious kiwifruit variety as scions. The scions should be 8-12cm long. Seal the upper end with wax or wound healing agent and cut the lower end into a smooth surface.

[0009] S3. Grafting: Using bark grafting or cleft grafting, two rootstocks are grafted in opposite directions onto the lower end of the same scion. The grafting area is wrapped with grafting film to form a kiwi seedling graft.

[0010] S4. Cultivating grafted seedlings: The grafted seedlings are cultivated in the nursery and transplanted into the field after the graft union has healed.

[0011] Furthermore, the rootstock stem is 0.4-0.6 cm in diameter and has 2-3 taproots; the scion stem is more than 1 cm in diameter and has more than one plump, complete bud.

[0012] In some specific embodiments, preferably, when grafting is performed using bark grafting, the specific details are as follows:

[0013] First, cut the upper part of the rootstock stem into a 2-3cm slanted surface, sharpening the top and making the cut surface thin. Then, cut a small slanted surface 0.2cm wide and 1.5-2cm long on each side of the cut, and a small slanted surface 0.2cm wide on the upper part of the back. Next, make a vertical cut in the bark from both sides of the lower end of the scion, 2-3cm long and deep to the xylem. Finally, insert the two rootstocks with the cut surfaces facing the xylem of the scion, close to the xylem, so that the rootstock is between the xylem and bark of the scion. Cover the two wounds on the rootstock with the inner sides of the bark, leaving the upper part of the rootstock slightly exposed to facilitate healing. After inserting the rootstock, immediately bind it tightly with grafting film.

[0014] In some specific embodiments, preferably, when the grafting method is cleft grafting, the specific details are as follows:

[0015] First, cut the upper part of the rootstock stem into 2-3cm long wedge-shaped bevels on both sides; then, use a grafting knife to vertically cut a 2.5-3.5cm long slit from the center of the lower end of the scion; finally, quickly insert the two prepared rootstocks, leaving 0.1-0.2cm of the cut surface of the rootstock outside to facilitate healing. Place the two rootstocks close to the two sides of the scion, aligning the cambium layers of the scion and rootstock, and then wrap the grafting area with grafting film.

[0016] Furthermore, before entering the nursery for cultivation, indoor pseudo-healing is carried out, as follows: the scions are placed with the roots facing down and neatly arranged on the seedbed; then covered with 2cm of fine sand, and water is sprayed as needed to keep the sand layer moist, and healing takes 15-20 days.

[0017] Furthermore, after the buds sprout during the cultivation process, promptly remove the buds that sprout from the rootstock to ensure the healthy growth of the scion buds; after the grafting site heals, remove the grafting film in a timely manner.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The kiwi seedlings cultivated by this invention possess two sets of root systems: one for Actinidia cuspidatum and the other for Actinidia deliciosa. Therefore, they not only exhibit strong resistance to waterlogging, drought, and pests and diseases, but also show excellent growth in grafted seedlings (survival rate 93.3-93.7%, budding rate 71.6-72.2%, branching rate 78.2-78.6%, fruit setting rate 87.1-88.6%). Furthermore, they absorb nutrients comprehensively, resulting in high-quality, high-yield fruit (single fruit weight reaches 90.7-91.6g, yield per mu 2461-2508kg, rich in various nutrients), thus offering significant economic benefits. Attached Figure Description

[0020] Figure 1 This is a flowchart of the double-rooted kiwifruit grafted seedling provided in Embodiment 1 of the present invention; wherein, a and e are rootstocks, b, c, and d are scions, f, g, and h are grafted seedlings, and i is a grafted seedling planted in a nursery.

[0021] Figure 2 This is a flowchart of the double-rooted kiwifruit grafted seedling provided in Embodiment 2 of the present invention; wherein, a, e, f, and g are rootstocks, b, c, and d are scions, h, i, and j are grafted seedlings, and k is a grafted seedling planted in a nursery. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0023] Example 1

[0024] This embodiment provides a method for cultivating grafted kiwifruit seedlings with dual root systems, as detailed below:

[0025] S1. Rootstock Acquisition: Select one one-year-old seedling of Actinidia cuspidata and one seedling of Actinidia deliciosa as rootstock. Both rootstocks should be robust, free from pests and diseases, with a stem diameter of about 0.5cm and 2-3 taproots. Prune the taproots of the two rootstocks to a length of 10-15cm, and retain 4-5cm of stem.

[0026] S2. Scion Acquisition: Select robust branches of the delicious kiwifruit variety (Qinhong) with a thickness of more than 1cm as scions. The scions should have more than one plump and complete bud and be 8-12cm long. Seal the upper end with wax or wound healing agent and cut the lower end into a smooth surface.

[0027] S3. Grafting: The kiwi seedling graft is formed by cleft grafting, as follows: First, cut the upper part of the rootstock stem into 2-3cm long wedge-shaped bevels on both sides; then, use a cleft grafting knife to gently cut a 2.5-3.5cm long vertical cleft from the center of the lower end of the scion; finally, quickly insert the two prepared rootstocks, leaving 0.1-0.2cm of the cut surface outside to facilitate healing. Place the two rootstocks close to the two sides of the scion, aligning the cambium layers of the scion and rootstock. Wrap the grafting area with grafting film to form the kiwi seedling graft.

[0028] S4. Cultivating grafted seedlings: Arrange the kiwi seedlings with the scion facing down and the roots facing up neatly on the seedbed; cover with 2cm of fine sand, spray water as needed to keep the sand layer moist, and allow it to heal for 18 days. Then place them in the nursery for cultivation. During the cultivation process, after the buds sprout, promptly remove the buds sprouting from the rootstock to ensure the healthy growth of the scion buds; after the grafting site has healed, remove the grafting film in time, and finally transplant them into the field for planting.

[0029] Example 2

[0030] This embodiment provides a method for cultivating grafted kiwifruit seedlings with dual root systems. The steps and methods are basically the same as in Embodiment 1, except that the grafting in step S3 is replaced by bark grafting; all other steps remain unchanged. The specific details of bark grafting are as follows:

[0031] First, cut the upper part of the rootstock stem into a 2-3cm slanted surface, sharpening the top and making the cut surface thin. Then, cut a small slanted surface 0.2cm wide and 1.5-2cm long on each side of the cut, and a small slanted surface 0.2cm wide on the upper part of the back. Next, make a vertical cut in the bark from both sides of the lower end of the scion, 2-3cm long and deep to the xylem. Finally, insert the two rootstocks with the cut surfaces facing the xylem of the scion, close to the xylem, so that the rootstock is between the xylem and bark of the scion. Cover the two wounds on the rootstock with the inner sides of the bark, leaving the upper part of the rootstock slightly exposed to facilitate healing. Immediately after inserting the rootstock, tightly bind it with grafting film to form a kiwi seedling graft.

[0032] Comparative Example 1

[0033] This comparative example provides a method for cultivating grafted kiwifruit seedlings with two root systems. The steps and methods are basically the same as those in Example 1, except that in step S1, both rootstocks are selected from Actinidia cuspidatum, while the rest remain unchanged.

[0034] Comparative Example 2

[0035] This comparative example provides a method for cultivating grafted kiwifruit seedlings with two root systems. The steps and methods are basically the same as those in Example 2, except that in step S1, both rootstocks are selected from Actinidia cuspidatum, while the rest remain unchanged.

[0036] Furthermore, in order to understand the differences in the growth of grafted seedlings and fruit quality in the above embodiments and comparative examples, the following statistics were also conducted.

[0037] Table 1. Growth of kiwifruit plants grafted onto different rootstocks

[0038]

[0039] As shown in Table 1, compared with 'Qin Hong' grafted onto two 'Qin Hong' rootstocks, grafted onto 'Actinidia cuspidatum' and 'Actinidia deliciosa' rootstocks had a better survival rate (93.3-93.7%), faster and stronger plant growth (main stem diameter reached 3.02-3.11 cm after three years), and significantly improved budding rate (71.6-72.2%), branching rate (78.2-78.6%), and fruit setting rate (87.1-88.6%). Cleft grafting and bark grafting were equally effective, and both grafting methods are well-suited for grafting kiwifruit seedlings with two root systems.

[0040] Table 2 Comparison of fruit quality of kiwifruit plants grafted onto different rootstocks

[0041]

[0042] Continued from the table above

[0043]

[0044] Table 2 shows that compared with 'Qin Hong' grafted onto two 'Qin Hong' rootstocks, grafted onto 'Actinidia cuspidatum' and 'Actinidia deliciosa' rootstocks, the grafted seedlings produced higher single fruit weight and yield per acre. The dry matter content and main nutrient content of the fruit also showed significant increases, with the most notable difference in phenol content (148.86~150.29 mg / 100g for the former and 43.97~44.01 mg / 100g for the latter). Similarly, the results of cleft grafting and bark grafting were comparable, and both grafting methods are well-suited for grafting kiwifruit seedlings with two root systems.

[0045] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market. Unless otherwise specified, the technical means used in the embodiments of this invention are conventional means well known to those skilled in the art.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for cultivating grafted kiwifruit seedlings with dual root systems, characterized in that, Includes the following steps: S1. Rootstock acquisition: Select one one-year-old seedling of Actinidia chinensis and Actinidia deliciosa as rootstock. Trim the main root of the two rootstocks to a length of 10-15cm and retain 4-5cm of stem. S2. Scion acquisition: Select branches of the delicious kiwifruit variety as scions. The scions should be 8-12cm long. Seal the upper end with wax or wound healing agent and cut the lower end into a smooth surface. S3. Grafting: Using bark grafting or cleft grafting, two rootstocks are grafted in opposite directions onto the lower end of the same scion. The grafting area is wrapped with grafting film to form a kiwi seedling graft. S4. Cultivating grafted seedlings: The grafted seedlings are cultivated in the nursery and transplanted into the field after the graft union has healed. The rootstock has a stem diameter of 0.4-0.6 cm and has 2-3 taproots; the scion has a stem diameter of more than 1 cm and has more than one plump, complete bud.

2. The method according to claim 1, characterized in that, When grafting is done using bark grafting, the specific steps are as follows: First, cut the upper part of the rootstock stem into a 2-3cm slanted surface, sharpening the top and making the cut surface thin. Then, cut a small slanted surface 0.2cm wide and 1.5-2cm long on each side of the cut, and a small slanted surface 0.2cm wide on the upper part of the back. Next, make a vertical cut in the bark from both sides of the lower end of the scion, 2-3cm long and deep to the xylem. Finally, insert the two rootstocks with the cut surfaces facing the xylem of the scion, close to the xylem, so that the rootstock is between the xylem and bark of the scion. Cover the two wounds on the rootstock with the inner sides of the bark, leaving the upper part of the rootstock exposed to facilitate healing. Immediately after inserting the rootstock, tightly bind it with grafting film.

3. The method according to claim 1, characterized in that, When cleft grafting is used, the specific steps are as follows: First, cut the upper part of the rootstock stem into 2-3cm long wedge-shaped bevels on both sides; then, use a grafting knife to vertically cut a 2.5-3.5cm long slit from the center of the lower end of the scion; finally, quickly insert the two prepared rootstocks, leaving 0.1-0.2cm of the cut surface of the rootstock outside to facilitate healing. Place the two rootstocks close to the two sides of the scion, aligning the cambium layers of the scion and rootstock, and then wrap the grafting area with grafting film.

4. The method according to claim 1, characterized in that, Before entering the nursery, indoor wound healing is carried out, as follows: the scions are placed with the roots facing down and neatly arranged on the seedbed; then covered with 2cm of fine sand, and water is sprayed as needed to keep the sand layer moist, and healing takes 15-20 days.

5. The method according to claim 1, characterized in that, After the buds sprout during the cultivation process, promptly remove the buds that sprout from the rootstock to ensure the healthy growth of the scion buds; after the grafting site heals, remove the grafting film promptly.

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