Methods to inhibit excessive growth of shoots sprouting below the fracture surface of large branches of *Juglans regia* and promote fruit production

Abstract

This application discloses a method for inhibiting excessive growth of shoots sprouting below the fracture surface of large branches of *Walnut yangbiense* and promoting fruit production, comprising the following steps: 1) After sawing off large branches of *Walnut yangbiense*, a sealing gel containing carbendazim and paclobutrazol is applied to the cut surface; 2) Below the fracture surface, a branch segment with a length of 45–55 cm is selected, and multiple incisions are made on the segment, extending to the xylem, with the incisions evenly distributed on the surface of the selected segment; 3) 190–210 g / tree of paclobutrazol, 1.5–2.5 kg / tree of NPK compound fertilizer, and 25–35 g / tree of rare earth powder are applied to the soil around the base of the trunk, followed by rotary tillage and soil covering. After implementation of this method, the new shoots sprouting below the fracture surface grow only 12–16 cm per year, far less than the annual growth length of the control treatments, demonstrating a good effect in controlling excessive growth of new shoots.

Description

Technical Field

[0001] This application relates to the field of Yangbi walnut cultivation technology, and in particular to a method for inhibiting the excessive growth of shoots sprouting below the fracture of large branches of Yangbi walnut and promoting fruiting. Background Technology

[0002] Currently, the main walnut varieties grown for their fruit are the deep-striped walnut (Juglans sigilllata D) and the common walnut (Juglans regia L). The deep-striped walnut variety is distributed in southwestern my country, with Yunnan province having the largest planting area. Yunnan ranks first in the country in terms of walnut cultivation area, yield, and output value. By the end of 2023, the province's cultivation area reached 43 million mu (approximately 3.8 million hectares), with an annual dried fruit output of about 2 million tons and an annual comprehensive output value of about 60 billion yuan.

[0003] Yangbi Paohe walnut is the most important cultivated variety of deep-striped walnut, accounting for over 85% of the walnut cultivation area in Yunnan. Yangbi Paohe walnut trees are characterized by their tall stature, reaching 15-18 meters in their natural growth state. Due to the height of the trees, mechanical equipment cannot meet the requirements of the mountainous environment, and harvesting mainly relies on workers using bamboo poles to climb the trees and knock the fruit down. This method suffers from low harvesting efficiency and high safety risks, resulting in walnut deaths and injuries every year in the production area. Furthermore, the harvesting cost is high, with 3-6 yuan per kilogram of dried walnuts. In the past five years, due to declining market prices and persistently low walnut purchase prices, the proportion of farmers abandoning harvesting from excessively tall trees in the production area due to harvesting difficulties has been increasing year by year.

[0004] To reduce the height of walnut trees, grafting is a common method. For example, the method for reducing the crown and controlling the crown of tall, bare-trunked walnut trees disclosed in CN202310847320.X involves cutting the main trunk of the walnut tree 1.5–2.2 meters above the ground and grafting scions onto it, thus reducing the height of the bare-trunked, tall-crowned walnut tree to 3–4 meters. This method is cumbersome and the maintenance of the grafted branches is difficult.

[0005] There are also measures to cut off the tops of large branches of walnut trees in Yangbi to reduce the overall height of the tree, thereby reducing harvesting risks and improving harvesting efficiency.

[0006] The process of cutting off large branches of walnut trees in Yangbi has the following characteristics:

[0007] 1. After a large branch of a Yangbi walnut tree is severed, new shoots can sprout from the dormant buds below the cut. Generally, after a large branch with a diameter of 10cm or more is severed, 5-10 new shoots can sprout in the second year. The large branch has sufficient stored nutrients, allowing new shoots to sprout from the trunk below the cut, resulting in vigorous growth. Although the cut is at the top of the branch, the strong apical dominance of the shoots near the cut leads to excessive growth in these new shoots. According to a survey conducted in Guangming Village, Dali from 2018 to 2023, without growth suppression treatment, the average length of new shoots sprouting below the branch cut can reach 1.4m for one year, 2.8m for two years, and 4.2m for three years. The excessive growth of these new shoots below the branch cut is severe.

[0008] New shoots sprouting from dormant buds on the trunk of the Yangbi walnut tree can only bear fruit after four years of continuous growth without removing the terminal buds. According to a survey conducted from 2018 to 2023, the fruiting rate of new shoots sprouting from the broken section of a large branch of the Yangbi walnut tree was 0% after 1 to 3 years, 35% in the 4th year, 68% in the 5th year, and 82% in the 6th year.

[0009] As can be seen from the above, the new shoots sprouting below the broken branches of large branches of Yangbi walnut trees exhibit the following problems: 1. The effect of cutting off large branches to reduce tree height is not good; 2. Fruiting is delayed, and the recovery of tree yield is slow, seriously affecting the tree yield within 5 years after the branch is cut off. Current technology lacks effective solutions to these problems. Conventional foliar spraying of bud-inhibiting agents is difficult to implement due to the high position of the sprouting shoots, resulting in poor effectiveness.

[0010] The information disclosed in the background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0011] This application provides a method for suppressing the excessive growth of shoots sprouting below the fracture surface of large branches of *Juglans regia* and promoting fruit production, addressing the aforementioned technical problems.

[0012] This application provides a method for inhibiting excessive growth of shoots sprouting below the fracture surface of a large branch of *Juglans regia* and promoting fruit production, comprising the following steps:

[0013] 1) After sawing off large branches from the large walnut tree in Yangbi, apply a sealing gel to the cut surface. The sealing gel contains carbendazim and paclobutrazol.

[0014] 2) Below the fracture, select a branch segment with a length of 45-55cm, and make multiple cuts on the branch segment, with the cuts reaching the xylem and the cuts evenly distributed on the surface of the selected branch segment.

[0015] 3) Apply 190-210g / tree of paclobutrazol, 1.5-2.5kg / tree of NPK compound fertilizer, and 25-35g / tree of rare earth powder to the soil around the base of the tree trunk, and then rotary till and cover with soil.

[0016] This method effectively inhibits the excessive growth of new shoots sprouting below the cut on large trees and shortens the fruiting time of these shoots, allowing them to bear fruit in just 3 years. It eliminates the need for manual climbing of the tree to prune and suppress excessive growth, reducing labor costs and improving operational safety. Similarly, applying a sealing gel to the wound prevents dehydration and rot, and promotes the sprouting of dormant buds.

[0017] Preferably, large branches of the Yangbi walnut tree should be sawed off during its dormant season when the leaves have fallen. Performing this operation during this time promotes wound healing and prevents rot.

[0018] Preferably, the diameter of the cut large branch is 10-20 cm.

[0019] Preferably, the large branches are cut 5-6 meters above the ground.

[0020] Preferably, the sealing gel contains a mixture of carbendazim and paclobutrazol in a mass ratio of 2:1.

[0021] Preferably, the branch segment selected in step 2) is located 1 to 2 meters below the break.

[0022] Preferably, the length of the branch segment selected in step 2) is 45-55cm; the distance between any two adjacent intersections in step 2) is 5-10cm. This distance can also be 5-20cm or 10-20cm.

[0023] Preferably, in step 3), the application operation is carried out within a radius of 1.5 to 2.5 m, with the base of the tree trunk as the center.

[0024] Preferably, the following are applied: 200g / plant of paclobutrazol, 2kg / plant of NPK compound fertilizer, and 30g / plant of rare earth powder. Preferably, the mass ratio of NPK in the NPK compound fertilizer is 15:15:15.

[0025] The beneficial effects that this application can produce include:

[0026] 1) The method provided in this application for inhibiting the excessive growth of new shoots sprouting below the fracture of large branches of Yangbi walnut and promoting fruiting, after the implementation of this method, the length of the new shoots sprouting below the fracture in the second year is 12-16cm, which is much lower than the length of the second year of growth of each treatment in the comparative example, and has a good effect on controlling the excessive growth of new shoots.

[0027] 2) The method provided in this application for inhibiting excessive growth of shoots sprouting below the fracture point of large branches of *Juglans regia* and promoting fruiting shows that, after treatment, the proportion of male flowering branches sprouting in the second year can reach over 85%, and the fruiting branch rate in the third year can reach over 87%. This is significantly higher than the effects of the treatments in the comparative studies, indicating that the method has a very significant effect on promoting fruiting. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments, but this does not limit the present invention in any way. Any modifications or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0029] Example

[0030] Unless otherwise specified, all materials used in the following examples were obtained through commercial channels.

[0031] Example 1

[0032] 1) Pruning large trees

[0033] In 2021, in the Guangming Walnut Garden in Yangbi County, during the dormant season of Yangbi walnut trees, from November to January of the following year, large branches with a diameter of 15cm were selected from the trees and cut off at a point 5.5m above the ground.

[0034] 2) Seal the broken surface

[0035] Apply a mixture of "sealing adhesive + carbendazim + paclobutrazol" to the cut surface of the large branch. The sealing adhesive, containing carbendazim and paclobutrazol, is a gel-based compound in which carbendazim and paclobutrazol are mixed at a mass ratio of 2:1. The gel used is carbomer (acrylic acid polymer).

[0036] Gel preparation method: First, add carbendazim and paclobutrazol to the white carbomer powder, then add water, and while stirring, add sodium hydroxide until a gel-like substance is formed. The concentration of sodium hydroxide used is 10%. Add 200L of water to 1kg of carbomer.

[0037] 3) Cutting branches

[0038] On the severed branch, within 1.5 to 2 meters below the cut, select a 50cm long branch segment. Make multiple cuts in the phloem of the selected branch segment with a knife, with the cuts reaching the xylem. The cuts should be spaced 5 to 10cm apart and evenly distributed on the surface of the selected branch segment.

[0039] 4) Soil-applied paclobutrazol

[0040] At the base of the tree trunk, evenly spread the following soil samples within a 2-meter radius of the trunk base: 200g of paclobutrazol per tree, 2kg of NPK compound fertilizer per tree, and 30g of rare earth powder (rare earth beneficial plant agent) per tree. Then, rotary till and cover with soil. The NPK compound fertilizer used has a N:P:K mass ratio of 15:15:15. The rare earth beneficial plant agent used is 200g of rare earth beneficial plant agent produced by Inner Mongolia Mengbang Yinong Biotechnology Co., Ltd.

[0041] Steps 1 through 4 must be completed one by one to ensure that all measures work simultaneously and none can be omitted.

[0042] Comparative Example 1: Pruning and shortening of overly vigorous branches

[0043] This method involves manually climbing the tree each year after a large branch is cut off, and pruning the tips of the new branches that sprout below the cut to promote the growth of new branches from the mother branch.

[0044] The cut end of the large branch is 5-6m above the ground. The new shoots that sprout from it will grow continuously for 4 years without removing the terminal bud before they can bear fruit. The new shoots that sprout from the mother branch are less than 4 years old. Therefore, after pruning and shortening the branches using this method, the new shoots will take 2-3 years longer to bear fruit.

[0045] Pruning and shortening new branches every year is labor-intensive and costly, and this operation can only prevent excessive growth of new branches, not promote fruit production. Practical observations show that when new branches sprouting below the cut of large branches are pruned annually, the fruit production rate of the current year's shoots in the sixth year after pruning is only 18%, while the tree height is 1.2 meters shorter than a tree without pruning the new shoots each year. This method only inhibits excessive growth of new branches.

[0046] Comparative Example 2: Soil-applied Paclobutrazol

[0047] The method involves applying 200g of paclobutrazol to the soil within 2 meters of the roots of each tree after the large branch is cut off.

[0048] After three years of using this method, the three-year-old branches sprouting below the broken branch were 2.8m long, the new shoots in the third year were 1.2m long, and there were no fruiting branches.

[0049] After this method was applied, the new shoots grew excessively and could not bear fruit earlier. The method did not achieve the effect of controlling excessive growth and promoting fruiting.

[0050] Comparative Example 3: Barium girdling of phloem

[0051] The method involves performing a spiral girdling treatment on the phloem within a range of 1 to 2 meters below the cut of a large branch.

[0052] The specific method is as follows: within a 1m length below the broken end of a large branch, peel off the phloem 3-5cm wide in a spiral motion.

[0053] In the third year after the implementation of this method, the three-year-old branches sprouting below the cut were 3.6m long, the new shoots in the third year were 1.2m long, and the fruiting branch rate was 5%. This method could not control excessive growth, nor could it promote fruiting.

[0054] Implementation results:

[0055] In the walnut grove of Guangming Village, Dali, the methods described in Example 1 and Comparative Examples 1-3 were implemented. Each method was applied to 20 large branches, and the new shoot growth length, percentage of male flowering branches, and percentage of fruiting branches of the Yangbi walnut trees were statistically analyzed year by year for each treatment. The statistical results are listed in Table 1:

[0056] Table 1

[0057]

[0058]

[0059] Note: The length of one-year-old new shoots refers to the length of newly sprouted branches in the current year; the length of four-year-old branches refers to the length of newly sprouted branches from the time they sprouted until the fourth year; after male flowers bloom on the branches of Yangbi walnut trees, the likelihood of the branches bearing fruit in the second year increases, so the percentage of male flower branches can indirectly reflect the fruiting rate of newly sprouted branches.

[0060] The results in Table 1 show that:

[0061] 1. The method in Example 1 can effectively suppress the annual growth length of new branches, and its effect is better than that of pruning and shortening in suppressing excessive growth. As can be seen from Table 1, the growth length of new branches is the shortest after using the method provided in this application.

[0062] 2. After the second year of implementation of the method provided in this application, the average growth of new shoots was only 16cm, which can continue to inhibit excessive growth. Moreover, after treatment with the method provided in this application, the rate of male flower branches on new branches was 85%, which was much higher than that of comparative proportions 1 to 3, which is conducive to improving the fruiting rate of new branches in the later stage.

[0063] 3. After three years of implementation of the method provided in this application, 87% of the new shoots yielded fruit, a better result than comparative examples 1-3. The average length of the new shoots that year was only 14 cm, far lower than the growth length of the new branches in comparative examples 1-3.

[0064] 4. After four years of implementation of the method provided in this application, 89% of the new shoots produced fruit, with an average growth of only 14 cm that year. The method provided in this application is far superior to comparative examples 1-3 in suppressing excessive shoot growth and improving the fruiting rate.

[0065] As shown in the table above, the method provided in this application is scientifically effective in significantly controlling the excessive growth of new shoots and promoting fruiting in new branches. The method of the invention is highly effective in controlling excessive growth and promoting fruiting.

[0066] Example 2

[0067] The difference from Example 1 is that the diameter of the cut branch is 10cm; the cut of the branch is 5m from the ground.

[0068] In step 3), the selected branch segment is located 1m below the cut; the length of the selected branch segment is 45cm; and the distance between the phloem cuts of any two adjacent branches is 20cm.

[0069] In step 4), apply the fertilizer within a radius of 1.5m, centered on the base of the tree trunk. Apply 190g of paclobutrazol per tree, 1.5kg of NPK compound fertilizer per tree, and 25g of rare earth powder per tree.

[0070] Example 3

[0071] The difference from Example 1 is that the diameter of the cut branch is 20cm; the cut branch is 6m above the ground.

[0072] In step 3), the selected branch segment is located 2m below the break; the length of the selected branch segment is 55cm; and the distance between any two adjacent road crossings is 5cm.

[0073] In step 4), apply the fertilizer within a radius of 2.5m, centered on the base of the tree trunk. Apply 210g of paclobutrazol per tree, 2.5kg of NPK compound fertilizer per tree, and 35g of rare earth powder per tree.

[0074] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for inhibiting excessive growth of shoots sprouting below the fracture surface of a large branch of *Juglans mandshurica* and promoting fruit production, characterized in that... Includes the following steps: 1) Pruning large trees During the dormant season of Yangbi walnut trees, from November to January of the following year, select large branches with a diameter of 15cm from the trees and cut them off 5.5m above the ground. 2) Seal the broken surface Apply a mixture of "sealing adhesive + carbendazim + paclobutrazol" to the cut wound of the large branch; apply a sealing adhesive containing carbendazim and paclobutrazol to the cut wound of the large branch. The sealing adhesive base is a gel, in which carbendazim and paclobutrazol are mixed at a mass ratio of 2:1; the gel used is carbomer. Gel preparation method: First, add carbendazim and paclobutrazol to white carbomer powder, then add water, and while stirring, add sodium hydroxide until a gel-like substance is formed; the concentration of sodium hydroxide used is 10%; 1 kg of carbomer is added to 200 L of water; 3) Cutting branches On the severed branch, within 1.5 to 2 meters below the cut, select a 50cm long branch segment. Make multiple cuts in the phloem of the selected branch segment with a knife, with the cuts reaching the xylem. The cuts should be spaced 5 to 10cm apart and evenly distributed on the surface of the selected branch segment. 4) Soil-applied paclobutrazol At the base of the tree trunk, evenly spread the following soil samples within a 2-meter radius of the base of the trunk: 200g of paclobutrazol per tree, 2kg of NPK compound fertilizer per tree, and 30g of rare earth powder per tree. Then, rotary till and cover with soil. The mass ratio of NPK in the NPK compound fertilizer is 15:15:

15. The rare earth powder used is rare earth beneficial plant extract. The rare earth beneficial plant extract is 200g of rare earth beneficial plant extract produced by Inner Mongolia Mengbang Yinong Biotechnology Co., Ltd.

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