Cultivation method for improving grafting survival rate of walnut seedlings

Abstract

The invention discloses a cultivation method for improving the grafting survival rate of walnut seedlings in the technical field of walnut grafting planting, which comprises the following steps: step 1, scion collection: according to natural environment conditions in different planting areas, selecting walnut improved seed mother trees of corresponding varieties as scion sources, and obtaining grafted scions; 2, rootstock selection and grafting: selecting a juglans regia tree as the rootstock, and then grafting the scions to juglans regia branches by adopting a high branch grafting method; step 3, management after grafting: building a sunshade net in the early stage of grafting, regularly observing the hydrops condition of grafting unions, and timely cleaning the hydrops; after scion buds germinate, rootstock buds are removed, and pesticide is sprayed regularly. According to the special ecological conditions of the planting area, the scions are accurately screened for grafting, and therefore the walnut seedling grafting survival rate is increased.

Description

Technical Field

[0001] This invention relates to the field of walnut grafting technology, specifically to a cultivation method for improving the survival rate of grafted walnut seedlings. Background Technology

[0002] Walnuts, recognized globally as an important woody oilseed tree species, hold a crucial position in the global agricultural industrial structure due to their dual economic and ecological value. Economically, walnut nuts are rich in high-quality unsaturated fatty acids (over 60%), plant protein (15%-20%), and various minerals such as calcium, phosphorus, and potassium. They are a core raw material for high-end edible oils, snack foods, and functional foods, demonstrating significant value in extending the industrial chain. Ecologically, as a deep-rooted tree species, walnut trees possess ecological functions such as water conservation, soil and water retention, and soil improvement. Especially in ecologically fragile areas such as karst landforms and arid-hot valleys, they are a preferred species for balancing economic benefits and ecological restoration. my country, as a major walnut producer, ranks first in the world in both planting area and yield. However, during the rapid development of the industry, the bottleneck of grafting and seedling cultivation technology has become a core issue restricting the improvement of the industry's quality and efficiency.

[0003] Taking Liangshan Prefecture as an example, relying on the unique three-dimensional climate conditions of the Hengduan Mountains, the area has a walnut planting scale of over 8 million mu (approximately 533,333 hectares), accounting for more than 35% of the total walnut planting area in Sichuan Province, making it a pillar industry for the local "forest granary" construction. However, Liangshan Prefecture is located on the eastern edge of the Qinghai-Tibet Plateau, with walnut planting areas ranging in altitude from 1,000 meters to 2,800 meters. Climate factors such as average annual temperature, precipitation, and frost-free period show significant vertical differentiation, and soil types alternate between red and yellow soils, brown and dark brown soils. This complex site condition makes the problem of insufficient adaptability of introduced varieties particularly prominent. According to statistics from the Liangshan Prefecture Forestry Research Institute over the past five years, the average survival rate of walnut seedlings cultivated using traditional grafting methods is only 65%-75%, and even lower than 50% in high-altitude (>2200 meters) or dry-hot valleys (<1500 meters) areas, directly causing annual seedling losses exceeding 30 million yuan.

[0004] Existing technologies also have many drawbacks. One aspect is the lack of a scientific system for variety selection. Traditional methods rely heavily on experience to select scions, failing to establish a correspondence between varieties and ecological factors. This leads to incompatibility issues such as "gum exudation at the graft union" and "bud stiffness" after grafting. Cold damage and drought alone can reduce grafted seedling yields by 30%-50%. More seriously, the low grafting survival rate has triggered a vicious cycle in the industry: due to unreliable regional trial data, the problem of "mixed varieties" is prominent in production, with low-efficiency forests accounting for more than 40%, and the average yield per mu only 60% of that in high-quality production areas. This situation not only restricts farmers' income but also wastes resources due to frequent variety changes, exacerbating the industry's dilemma of "variety degradation - low efficiency."

[0005] Therefore, this invention proposes a cultivation method to improve the survival rate of grafted walnut seedlings in order to solve the above problems. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a cultivation method for improving the grafting survival rate of walnut seedlings. This method involves precisely selecting scions for grafting based on the specific ecological conditions of the planting area, thereby increasing the grafting survival rate of walnut seedlings.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A cultivation method for improving the grafting survival rate of walnut seedlings, comprising the following steps:

[0008] Step 1: Scion Collection: Based on the natural environmental conditions of different planting areas, select high-quality walnut mother trees of the corresponding varieties as the source of scions to obtain grafting scions;

[0009] Step 2, Rootstock Selection and Grafting: The rootstock is selected from walnut trees, and then the scion is grafted onto the walnut tree branches using the high-branch grafting method.

[0010] Step 3: Post-grafting management: In the early stage of grafting, set up a shade net and regularly observe the sap accumulation at the graft union, and clean up the sap in time; after the scion buds sprout, remove the rootstock buds and spray the scion with pesticides regularly.

[0011] Furthermore, in step one, the scions are collected during the tree's dormant period. The collection criteria are healthy, disease-free, one-year-old branches with a diameter of 0.8-1.2 cm and plump buds.

[0012] Furthermore, the high-branch grafting method specifically includes: cutting the main branch of the rootstock at a smooth point, cutting the cut surface into a 30° bevel and making a 2-3cm downward cut; cutting the lower end of the scion into a 2-3cm long wedge-shaped bevel, inserting it into the rootstock cut and aligning the cambium layers.

[0013] Furthermore, the specific process for obtaining the correspondence between planting areas and superior walnut mother tree varieties in step one is as follows:

[0014] a. Select several original certified superior walnut mother trees and selected superior plants of various varieties as the source of cuttings. The cuttings obtained from the original certified superior walnut mother trees and selected superior plants are defined as experimental cuttings. Select the main walnut varieties planted in the planting area as the source of cuttings. The obtained cuttings are defined as control cuttings. The rootstock of each planting area is selected as walnut tree.

[0015] b. Several regional experimental sites with different ecological niches were set up for each variety of experimental scion; the regional experimental sites were set up according to randomized block design and repeated 3 times. Five plants of each variety were grafted onto each repeated experimental scion, and one plant of the main walnut variety planted in the planting area was grafted onto it as a control.

[0016] c. Obtain phenological observation indicators within the regional test sites, and assess flowering habits based on the timing of female and male flower appearance; investigate environmental factors at the regional test sites, and simultaneously observe and investigate cold damage, drought, disease, and insect infestations on experimental and control scions, and divide the walnut variety's suitable regions after comprehensive analysis; compare the nut indicators of fruits obtained from experimental scions with those obtained from control scions, and statistically analyze to determine the degree of yield and quality.

[0017] d. Use correlation analysis to analyze the correlation between variables at experimental sites in the corresponding region, infer the suitability of walnut varieties, and then organize and analyze the data to obtain breeding strategy data to assist in the selection of walnut varieties in different planting areas.

[0018] Furthermore, phenological observation indicators include: leaf buds, leaves, branches, female flowers, male flowers, fruits, flowering habits, and yield measurement.

[0019] Furthermore, nut indicators include: appearance, average nut weight, kernel, flavor, shell thickness, kernel yield, and chemical indicators.

[0020] Furthermore, the number of ecological niches set for each variety's experimental spikelets is at least three.

[0021] Furthermore, the area of ​​each experimental site is greater than 30 mu.

[0022] Furthermore, the graft union is tightly wrapped from bottom to top with a 0.02mm thick polyethylene film strip, leaving only the scion bud exposed.

[0023] Furthermore, in step three, the observation period for the grafting interface is 3-5 days.

[0024] The above-mentioned approach has the following beneficial effects: 1. This approach establishes a precise correspondence between walnut varieties and planting areas through systematic regional trials and scientific analysis, solving the grafting obstacles caused by variety-environment mismatch in traditional methods. Specifically, in the variety selection stage, by setting up regional experimental sites with multiple ecological niches (covering different natural environmental conditions) and combining randomized block design, phenological characteristics (such as leaf bud germination and flowering time), environmental adaptability (such as cold resistance, drought resistance, and disease and pest resistance), and fruit quality (such as appearance, flavor, and kernel yield) are comprehensively observed, and the performance of different varieties in specific regions is comprehensively evaluated. By comparing the various indicators of experimental scions and control scions, walnut varieties highly adapted to the ecological conditions of the target area can be accurately selected (such as selecting drought-resistant varieties in arid areas and disease-resistant varieties in rainy areas). This scientific strategy of "selecting varieties according to local conditions" reduces the risk of grafting incompatibility (such as gumming at the graft union and bud stunting) from the source of scion selection, significantly improves the adaptability of grafted seedlings to the planting environment, and lays a good foundation for subsequent growth.

[0025] 2. This program effectively improves graft union healing efficiency and new shoot vigor through standardized procedures and meticulous management of the entire grafting process. In the rootstock selection and grafting stages, only walnut rootstocks with superior compatibility are used, and pre-treatment through pruning (retaining the main branch and applying a healing agent) enhances nutrient supply to the graft union. In the high-branch grafting method, the angle and depth of the cut surfaces of the rootstock and scion are strictly regulated to ensure close alignment of the cambium layers. Combined with breathable and moisture-retaining film wrapping technology, a stable microenvironment is created for graft union healing. In post-grafting management, measures such as setting up shade nets to control light intensity, regularly spraying water to maintain graft union humidity, promptly removing rootstock buds to reduce nutrient competition, and targeted pesticide application to control pests and diseases comprehensively guarantee the temperature, humidity, and nutrient conditions required for graft union healing. This combination of standardized operations and meticulous management significantly shortens the graft union healing cycle, promotes vigorous new shoot growth, and systematically improves graft survival rate and seedling quality from a technical perspective.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating an embodiment of the cultivation method for improving the grafting survival rate of walnut seedlings according to the present invention. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0029] The following detailed description illustrates the specific implementation method:

[0030] Example:

[0031] As attached Figure 1 As shown, a cultivation method for improving the grafting survival rate of walnut seedlings includes the following steps:

[0032] Step 1: Scion Collection: Based on the natural environmental conditions of different planting areas, select high-quality walnut mother trees of the corresponding varieties as the source of scions to obtain grafting scions; the scion collection time is during the tree's dormancy period (December to February of the following year), and the collection standard is one-year-old branches that are free from diseases and pests, with a branch diameter of 0.8-1.2cm and plump buds.

[0033] The specific process for obtaining the correspondence between planting areas and superior walnut mother tree varieties is as follows:

[0034] a. Select several original certified superior walnut mother trees and selected superior plants of various varieties as the source of cuttings. The cuttings obtained from the original certified superior walnut mother trees and selected superior plants are defined as experimental cuttings. Select the main walnut varieties planted in the planting area as the source of cuttings. The obtained cuttings are defined as control cuttings. The rootstock of each planting area is selected as walnut tree.

[0035] b. At least three regional experimental sites with different ecological niches were set up for each variety of experimental scion; the regional experimental sites were set up according to randomized block design and repeated three times. Five plants of each variety were grafted onto each repeated experimental scion, and one plant of the main walnut variety planted in the planting area was grafted onto it as a control.

[0036] In addition, the principles and requirements for selecting regional experimental sites are as follows: regional experimental sites should be selected from walnut forests that are concentrated in one area, have good growth, are easily accessible, and have an area of ​​more than 30 mu.

[0037] c. Obtain phenological observation indicators within the regional test sites, and assess flowering habits based on the timing of female and male flower appearance; investigate environmental factors at the regional test sites, and simultaneously observe and investigate cold damage, drought, disease, and insect infestations on experimental and control scions, and divide the walnut variety's suitable regions after comprehensive analysis; compare the nut indicators of fruits obtained from experimental scions with those obtained from control scions, and statistically analyze to determine the degree of yield and quality.

[0038] The phenological observation indicators mainly include: leaf buds (budding stage, opening stage, leaf expansion stage), leaves (growing stage, color change stage, leaf fall stage), branches (new shoot growth begins, new shoot growth stops, secondary growth begins, branch maturity stage), female flowers (initial flowering stage, full bloom stage, late flowering stage), male flowers (initial flowering stage, full bloom stage, late flowering stage, flower fall stage), fruits (young fruit emergence stage, physiological fruit drop stage, fruit maturity stage), flowering habits (male-premature varieties, female-premature varieties, varieties with both male and female premature varieties), and yield measurement. Nut indicators include: appearance (fruit shape, fruit surface, suture line height, suture line tightness), average fruit weight (g), kernel (average kernel (g), kernel color, ease of kernel extraction, plumpness), flavor, shell thickness (mm), kernel yield (%), and chemical indicators (fat content %), protein content %).

[0039] d. Use correlation analysis to analyze the correlation between variables at experimental sites in the corresponding region, infer the suitability of walnut varieties, and then organize and analyze the data to obtain breeding strategy data to assist in the selection of walnut varieties in different planting areas.

[0040] Step 2, Rootstock Selection and Grafting: The rootstock is selected from walnut trees, and then the scion is grafted onto the walnut tree branches using the high-branch grafting method.

[0041] The high-branch grafting method specifically includes: cutting the main branch of the rootstock at a smooth point, shaping the cut surface into a 30° bevel and making a 2-3cm downward cut; shaping the lower end of the scion into a 2-3cm long wedge, inserting it into the rootstock cut and aligning the cambium layers; then tightly wrapping the graft union from bottom to top with a 0.02mm thick polyethylene film strip, leaving only the scion bud exposed. This method is also applicable to the step of obtaining the correspondence between planting areas and superior walnut mother tree varieties.

[0042] Step 3: Post-grafting management: In the early stage of grafting, set up a shade net and observe the sap accumulation at the grafting point every 3-5 days, and clean up the sap in time; after the scion buds sprout, remove the rootstock buds and spray the fungicide regularly.

[0043] Based on the above, an experiment was conducted to obtain the correspondence between planting areas and superior walnut mother tree varieties (taking walnut planting in Liangshan Prefecture as an example), as detailed below:

[0044] I. Experimental Materials:

[0045] Experimental varieties: 1. Mother trees of 12 previously recognized superior walnut varieties: Zhuangyuanhuang, Mianning Zirong, Lifeng Zirong, Xiangsu No. 1, Bailong No. 1, Kangwu No. 1, Leixi, Xiluo Zaoke, Ziyue, Jinling No. 1, Daliangshan Ziyi Zaoshu No. 1, and Daliangshan Ziyi Wanshu No. 2; 2. Selected superior trees: superior trees named "Xiluo Zaoshu" selected in Leibo County and superior trees named "Lada Zike" selected in Butuo County. A total of 14 experimental varieties were included.

[0046] Control varieties: The main walnuts grown in the counties and cities where the test sites are located in each region are used as control varieties.

[0047] II. Experimental Location:

[0048] 1. Number of regional trial sites: Three regional trial sites (Dechang, Huidong and Mianning) with different ecological niches are set up for each variety, and a total of 42 regional trial sites are needed for 14 varieties.

[0049] 2. Setup and distribution of regional test sites:

[0050] Table 1 - Regional Test Site Setup Table

[0051]

[0052]

[0053] Data acquisition and analysis were conducted based on the above-mentioned process of obtaining the correspondence between planting areas and superior walnut mother tree varieties.

[0054] The effectiveness of this solution compared to existing technologies is as follows:

[0055] Table 2 - Comparative Advantage Data Table

[0056]

[0057] As shown in Table 2, this method significantly outperforms existing technologies in several core indicators of walnut seedling grafting and cultivation. Traditional methods suffer from inaccurate scion selection, resulting in a grafting survival rate of only 65%-75%, and low variety-regional compatibility, making them susceptible to yield reductions of 30%-50% due to cold damage and drought. In contrast, this method, through precise collection of high-quality scions (0.8-1.2cm in diameter) during dormancy, standardized high-branch grafting (30° incision + aligned cambium), and shade netting for moisture retention, increases the survival rate to 82%-93%. Furthermore, analysis of regional trial sites (phenological observation, environmental survey, and stress resistance statistics) shows a variety adaptability matching rate exceeding 90%, significantly reducing the risk of yield reduction. In terms of quality and yield, the kernel yield of traditional main varieties is only 45%-50% and the yield per plant is 5-8kg, while the kernel yield of the experimental varieties in this program reaches 53%-58% and the yield per plant is 8-12kg, increasing the yield by 30%-50%. At the same time, the management of bud removal and spraying after grafting reduces the incidence of pests and diseases from 20%-30% to ≤10%, and the standardized operation (clear cut angle and wrapping requirements) further reduces the survival rate fluctuation from ±15% to ≤5%, resulting in a significant improvement in overall benefits.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A cultivation method for improving the grafting survival rate of walnut seedlings, characterized in that, Includes the following steps: Step 1: Scion Collection: Based on the natural environmental conditions of different planting areas, select high-quality walnut mother trees of the corresponding varieties as the source of scions to obtain grafting scions; Step 2, Rootstock Selection and Grafting: The rootstock is selected from walnut trees, and then the scion is grafted onto the walnut tree branches using the high-branch grafting method. Step 3: Post-grafting management: In the early stage of grafting, set up a shade net and regularly observe the sap accumulation at the graft union, and clean up the sap in time; after the scion buds sprout, remove the rootstock buds and spray the scion with pesticides regularly.

2. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 1, characterized in that: In step one, the scions are collected during the tree's dormant period. The collection criteria are healthy, one-year-old branches free from pests and diseases, with a branch diameter of 0.8-1.2cm and plump buds.

3. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 1, characterized in that: The high-branch grafting method specifically includes: cutting the main branch of the rootstock at a smooth point, cutting the cut surface into a 30° bevel and making a 2-3cm downward cut; cutting the lower end of the scion into a 2-3cm long wedge-shaped bevel, inserting it into the rootstock cut and aligning the cambium layers.

4. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 3, characterized in that: The specific process for obtaining the correspondence between planting areas and superior walnut mother tree varieties in Step One is as follows: a. Select several original certified superior walnut mother trees and selected superior plants of various varieties as the source of cuttings. The cuttings obtained from the original certified superior walnut mother trees and selected superior plants are defined as experimental cuttings. Select the main walnut varieties planted in the planting area as the source of cuttings. The obtained cuttings are defined as control cuttings. The rootstock of each planting area is selected as walnut tree. b. Several regional experimental sites with different ecological niches were set up for each variety of experimental scion; the regional experimental sites were set up according to randomized block design and repeated 3 times. Five plants of each variety were grafted onto each repeated experimental scion, and one plant of the main walnut variety planted in the planting area was grafted onto it as a control. c. Obtain phenological observation indicators within the regional test sites, and assess flowering habits based on the timing of female and male flower appearance; investigate environmental factors at the regional test sites, and simultaneously observe and investigate cold damage, drought, disease, and insect infestations on experimental and control scions, and divide the walnut variety's suitable regions after comprehensive analysis; compare the nut indicators of fruits obtained from experimental scions with those obtained from control scions, and statistically analyze to determine the degree of yield and quality. d. Use correlation analysis to analyze the correlation between variables at experimental sites in the corresponding region, infer the suitability of walnut varieties, and then organize and analyze the data to obtain breeding strategy data to assist in the selection of walnut varieties in different planting areas.

5. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 4, characterized in that: Phenological observation indicators include: leaf buds, leaves, branches, female flowers, male flowers, fruits, flowering habits, and yield measurement.

6. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 4, characterized in that: Nut indicators include: appearance, average nut weight, kernel, flavor, shell thickness, kernel yield, and chemical properties.

7. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 4, characterized in that: Each variety's experimental scions should be assigned to at least three ecological niches.

8. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 4, characterized in that: Each experimental site covers an area of ​​more than 30 mu (approximately 2 hectares).

9. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 3, characterized in that: Use a 0.02mm thick polyethylene film strip to tightly wrap the graft union from bottom to top, leaving only the scion bud exposed.

10. The cultivation method for improving the grafting survival rate of walnut seedlings according to claim 1, characterized in that: In step three, the observation period for the grafting interface is 3-5 days.

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