Method for shaping and pruning of Idesia polycarpa Maxim. and application thereof

Abstract

The application provides a shaping pruning method for Idesia polycarpa Maxim and application thereof. The shaping pruning method is a trunk cutting treatment for a fruiting large tree, and 3 layers of fruiting branches are reserved. The application comprises the following aspects: optimization of photosynthetic capacity, tree structure, fruiting capacity, fruit yield and quality, oil yield and oil component of Idesia polycarpa Maxim.

Description

Technical Field

[0001] This invention relates to forest tree shaping technology, specifically, a method for shaping and pruning *Vernicia fordii* and its application. Background Technology

[0002] *Idesia polycarpa*, belonging to the Salicaceae family, is a distinctive woody oilseed tree species in my country. The entire fruit can be pressed for oil, with a high oil content and excellent oil quality (Chen Ziqian, 2023; Zuo et al., 2024). Mature fruit contains 39.4–43.6% oil, rich in linoleic acid (over 70%), vitamin E, squalene, and other health-promoting components beneficial to the cardiovascular system (RANA et al., 2021; Lu Xiang et al., 2010; Wu Zhiwen et al., 2010; He Huahan et al., 2025). *Idesia polycarpa* oil can be used as edible oil, biodiesel, and is also a raw material for pharmaceuticals and health products (RANA et al., 2021), and can also be used as an industrial lubricant. The tree has a straight trunk, distinct branching, and its ripe fruit is red, yellow, or orange, with a fruiting period of up to 6 months, giving it high value for timber and ornamental purposes. Seedlings of the Chinese tallow tree generally bear fruit in the 3rd to 5th year after planting, with a productive period of up to 40 years. During the productive period, a single tree can produce about 10 to 30 kg of fresh fruit, earning it the nickname "oil depot on the tree" (Lu Xiang et al., 2010; Zhang Xuan and Lü Mingrui, 2021).

[0003] Currently, there are many measures for dwarfing fruit trees, but fewer for dwarfing forest trees. For example, dwarfing of apple, pear, and peach trees is primarily achieved through the use of dwarfing rootstocks, simultaneously aiming for high yield, drought resistance, tolerance to poor soil, salt tolerance, and cold resistance (Xie Yuanmei et al., 2022; Lu Chao et al., 2013; Alatantuya et al., 2023). However, dwarfing treatments are rarely applied to forest trees, especially mature trees.

[0004] The *Vernicia fordii* is a tall tree, reaching heights of over 20 meters, and the height of its fruiting layer can hinder fruit harvesting. Furthermore, the dense growth of the upper whorls causes severe death of lower fruiting branches, significantly impacting yield and leading to premature fruit loss. Current research on the tree shape and structure of *Vernicia fordii* primarily focuses on growth indicators such as the main branches and twigs. For example, traditional studies often involve pruning one-year-old seedlings, followed by four years of continuous treatment to achieve dwarfing. However, this research only indicates increased yield and does not address the effects of pruning on fruit quality and oil content during the fruiting period. Furthermore, research on pruning techniques for dwarfing mature fruit-bearing trees has not yet been conducted. Summary of the Invention

[0005] The present invention aims to overcome the above-mentioned defects by pruning the trunks of mature *Vernicia fordii* trees to achieve dwarfing. Further research is needed on the growth of the dwarfed trees, the growth indicators of the fruit clusters and fruits, and the response of oil-related indicators to the pruning.

[0006] This invention discloses a method for shaping and pruning *Vernicia fordii*, namely, pruning the trunk of mature fruiting trees, retaining three layers of fruiting branches or keeping the tree height no higher than 4.5 meters. These mature fruiting trees are over 7 years old and have entered their peak fruiting period. These trees have significant drawbacks: excessive height makes harvesting difficult, dense upper whorls cause severe death of lower fruiting branches, seriously affecting yield, and often leading to premature yield reduction and poor quality. Currently, there is no good solution to address these problems in these trees.

[0007] Furthermore, the research of this invention also discovered the following application scenarios based on the above-mentioned shaping and pruning method for *Vernicia fordii*, namely:

[0008] The pruning and shaping methods of *Vernicia fordii* can be applied to optimize its photosynthetic capacity, such as increasing leaf area, leaf circumference, and maximum leaf width, while shortening petiole length.

[0009] Application of shaping and pruning methods for *Vernicia fordii* in optimizing the tree structure.

[0010] Application of shaping and pruning methods for improving the fruiting ability of *Vernicia fordii*.

[0011] The pruning and shaping methods of *Vernicia fordii* can be applied to improve the yield and quality of *Vernicia fordii* fruits. For example, without changing the shape of individual fruits, they can promote the longitudinal growth of fruit clusters, increase the overall weight of fruit clusters and the fullness of fruits, thereby increasing yield.

[0012] Application of pruning and shaping methods for improving the oil yield of *Vernicia fordii*.

[0013] Application of pruning and shaping methods for *Vernicia fordii* in optimizing the oil composition of *Vernicia fordii*. Attached Figure Description

[0014] Figure 1 The budding (A) and fruiting (C) stages of *Vernicia fordii* after stem cutting, compared with the budding (B) and fruiting (D) stages of control. Detailed Implementation

[0015] 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.

[0016] Example 1. Experimental Method

[0017] The experimental site was located in Guiding County, Guiyang City, Guizhou Province (107°08′~107°15′E, 26°40′~26°47′N), with an average altitude of 1000~1300 meters. This region has a mid-subtropical monsoon humid climate, with a multi-year average temperature of 15.5℃, an accumulated temperature above 0℃ of 5198.5℃, and an average precipitation of 1084.8 mm (data collected from the Guiding County People's Government website, https: / / www.guiding.gov.cn / ). At the end of 2024, this study selected 80 healthy 7-year-old *Vernicia fordii* fruit-bearing trees, with an average tree height of 6.8±0.42 m. Trees with relatively consistent fruit size, number of fruit clusters, and yield were selected for this experiment.

[0018] set up:

[0019] Experimental group: 40 trees were pruned after fruit harvest, retaining 3 layers of fruiting branches, with a height of approximately 4 ± 0.36 m. The main objective of this study was dwarfing; if 2 layers of fruiting branches reached 4 m, we would try to maintain that height rather than 3 layers. However, our investigation of the relevant fruiting layers revealed that the *Vernicia fordii* trees used in this project were all 7-year-old fruiting trees. Generally, *Vernicia fordii* trees begin to bear fruit at 5 years old, and 7 years old is the peak fruiting period. At this time, *Vernicia fordii* trees have about 5 layers of fruiting branches, with the bottom 3 layers bearing the most fruit (the top 2 layers not bearing fruit), resulting in the highest yield, and the phenomenon of 2 layers is extremely rare. Pruning the trunk to only 3 layers ensures yield, and the experiment showed that both fruit yield and quality can be achieved.

[0020] If only one layer is retained, the yield will be directly reduced. If there are more than four layers, the purpose of dwarfing cannot be achieved. That is, the height has exceeded 4m and can reach more than 6m, thus losing the purpose of dwarfing by cutting off the trunk.

[0021] Control group: 40 *Vernicia fordii* plants without any treatment.

[0022] Routine management practices, such as watering, fertilization amount, fertilization method, pesticide application, and weeding, are all managed consistently.

[0023] Example 2. Performance Testing

[0024] 2.1. Test Method

[0025] 2.1.1. Methods for determining tree traits

[0026] The base of the *Vernicia fordii* plant was used as the measurement reference point, and the vertical height was measured using the vertical measurement method. For both the control and trunk-cutting groups, measurements were taken from three different locations on five trees, and the average value was taken (accuracy to 0.01m). Crown width was measured using the radial projection method, and the average value was taken after measuring the projected diameter of branches in the east-west and north-south directions (accuracy to 0.01m). The number of tree layers was determined by dividing the plant into natural layers from bottom to top using the main trunk as the reference axis, and the number of effective branch layers was recorded. From the base to the top of the plant, the fruiting condition of all fruiting branches was checked, and the total number of fruiting layers and fruit clusters per tree was counted. The results are as follows: Figure 1 As shown.

[0027] 2.1.2. Leaf Measurement Method

[0028] Ten healthy, intact, and uniform mature leaves were taken from each of the four locations of the cut-off stem and control plants. Leaf area, leaf circumference, leaf length, leaf width, aspect ratio, and petiole length were measured using a scanning leaf area meter (model: YMJ-S).

[0029] 2.1.3. Methods for determining fruit traits

[0030] In mid-to-late October, five bunches of plump, pest-free mature fruit were selected from four different locations on both the cut-off and control *Vernicia fordii* trees and brought back to the laboratory. The length and width were measured using a steel tape measure (accurate to 1 mm), and the average value was taken. The transverse diameter, longitudinal diameter, circumference, weight of 5 fruits, weight of a single fruit, and weight of 1000 fruits were measured using an automatic seed analysis instrument (model: IN-KZ02, Shandong Zhonghong Optoelectronic Technology Co., Ltd.).

[0031] 2.1.4. Methods for determining the oil content and oil composition of fruits

[0032] After harvesting, the fresh fruits of *Vernicia fordii* (both cut-off and control varieties) were placed in an oven and blanched at 105℃ for 15 minutes. The temperature was then adjusted to 60℃ until all fruits were completely dried and their quality remained constant. Oil content and lipid composition were determined by Shanghai Yuanxin Biotechnology Co., Ltd. (https: / / www.shyx-bio.com / ). Oil content was determined according to GB / T 6433-1994 / ISO 6492:1999 "Determination of Crude Fat in Feed," using Soxhlet extraction. The composition of eight fatty acids was determined according to the gas chromatography method provided by Wang (Wang et al., 2025).

[0033] Note: Data Analysis

[0034] Data such as mean and standard deviation were analyzed using SPSS 26.0, and significant differences were determined using t-tests. Images were created using Origin 2021 and Adobe Illustrator 2022.

[0035] 2.2. Test Results and Analysis

[0036] 2.2.1 Effects of trunk pruning on the tree structure and fruit production of *Vernicia fordii*

[0037] As shown in Table 1, two years after the trunk was cut off, the plant height of the control group was 6.21±0.95m, and the plant height of the trunk-cutting group was 4.13±0.52m, a decrease of 33.49%, and the difference between the two groups was extremely significant (t=6.07, P<0.01).

[0038] The crown width of the control group was 5.46±1m, and the crown width of the trunk-cutting group was 5.1±0.58m, a decrease of 6.59%, but there was no significant difference between the two groups (t=0.985, P>0.05).

[0039] The number of layers in the control group was 4.47±0.62, while the number of layers in the stem-cutting group was 3.12±0.72, a decrease of 30.20%. The difference between the two groups was extremely significant (t=4.52, P<0.01).

[0040] The number of layers in the control group was 2.94±0.77, while the number of layers in the stem-cutting group was 3.13±0.67, an increase of 6.46%. The number of layers increased slightly, but there was no significant difference between the two groups (t=-0.589, P>0.05).

[0041] The number of ears in the control group was 128.24±13.94, and the number of ears in the pruning group was 153.25±22.61, an increase of 19.50%. There was a highly significant difference between the two groups (t=-2.978, P<0.01).

[0042] Table 1. Comparison and results indicators of *Vernicia fordii* trees with and without trunk pruning.

[0043]

[0044] 2.2 Effects of stem cutting on the leaves of *Vernicia fordii*

[0045] As shown in Table 2, the leaf area of ​​the control group was 114.06±10.89 cm², and the leaf area of ​​the trunk-cutting group was 128.51±8.36 cm², an increase of 12.67%, with a significant difference between the two groups (t=2.103, P<0.05).

[0046] The leaf circumference of the control group was 64.11±5.8cm, while that of the stem-cutting group was 67.73±7.95cm, an increase of 5.65%. The difference between the two groups was extremely significant (t=3.887, P<0.01).

[0047] The leaf length of the control group was 19.86±4.17cm, and the leaf length of the truncated group was 21.36±4.97cm, an increase of 7.55%, but there was no significant difference (t=1.134, P>0.05).

[0048] The maximum leaf width in the control group was 11.04±1.9cm, while the maximum leaf width in the stem-cutting group was 12.12±1.53cm, an increase of 9.78%. There was no significant difference between the two groups (t=1.609, P>0.05).

[0049] The leaf aspect ratio of the control group was 1.88±0.29, while that of the truncated group was 1.82±0.18, a decrease of 3.19%, but there was no significant difference between the two groups (t=0.356, P>0.05).

[0050] The petiole length in the control group was 14.89±1.21cm, while the petiole length in the stem-cutting group was 12.83±2.1cm, a decrease of 13.83%. There was a highly significant difference between the two groups (t=-2.646, P<0.01).

[0051] The average leaf width in the control group was 9.97±2.2 cm, while the average leaf width in the stem-cutting group was 9.83±2.07 cm, a decrease of 1.40%. There was no significant difference between the two groups (t=-0.803, P>0.05).

[0052] Table 2. Indicators of *Vernicia fordii* leaves compared with those of cut-off leaves.

[0053]

[0054] 2.3 Effects of stem cutting on the fruit and bunches of *Vernicia fordii*

[0055] As shown in Table 3, the ear length of the control group was 24.5±2.18cm, and the ear length of the truncated group was 26.5±2.85cm, which was significantly increased by 8.16% (t=-1.972, P<0.05). There was a significant difference between the two groups.

[0056] The ear width in the control group was 9.67±1.05cm, while the ear width in the truncated group was 8.62±1.1cm, a significant decrease of 10.86% (t=2.183, P<0.05), showing a significant difference between the two groups.

[0057] The weight of the ear of fruit in the control group was 70.81±4.22g, while the weight of the ear of fruit in the pruning group was 84.54±3.16g, which was significantly higher by 19.39% (t=−8.236, P<0.01). There was a highly significant difference between the two groups.

[0058] The length of a single fruit in the control group was 0.6±0.02cm, while the length of a single fruit in the pruning group was 0.61±0.03cm, an increase of 1.67% (t=-0.877, P>0.05).

[0059] The width of a single fruit in the control group was 0.57±0.042cm, while the width of a single fruit in the pruning group was 0.59±0.031cm, an increase of 3.51% (t=-1.212, P>0.05).

[0060] The area of ​​a single fruit in the control group was 0.29±0.014 cm², while the area of ​​a single fruit in the pruning group was 0.28±0.015 cm², a decrease of 3.45% (t=1.541, P>0.05).

[0061] The circumference of a single fruit in the control group was 2.03±0.12cm, while the circumference of a single fruit in the stem-cutting group was 2.04±0.14cm, an increase of 0.49% (t=-0.171, P>0.05).

[0062] The weight of a single grain in the control group was 0.45±0.02g, while the weight of a single grain in the dried grain group was 0.48±0.05g, an increase of 6.67% (t=-1.762, P>0.05).

[0063] The average weight of 5 fruits in the control group was 2.23±0.17g, while the average weight of 5 fruits in the dried group was 2.38±0.21g, an increase of 6.73% (t=-1.756, P>0.05).

[0064] The thousand-grain weight of the control group was 448.82±11.04g, and the thousand-grain weight of the dried group was 475.76±9.54g, an increase of 6.00% (t=-5.839, P<0.01).

[0065] Table 3. Indicators of *Vernicia fordii* fruit compared with those of dried *Vernicia fordii*.

[0066]

[0067] 2.4 Effects of drying treatment on the oil content of *Vernicia fordii* fruit

[0068] As shown in Table 4, the oil content of the control group was 17.71±2.24%, while the oil content of the dried group was 21.17±1.93%, which was significantly higher by 19.54% (t=4.23, P<0.05).

[0069] The palmitic acid content in the control group was 18.49±1.28%, while that in the truncated group was 18.35±2.28%, a decrease of 0.76%. The difference between the two groups was not significant (t=0.21, P>0.05).

[0070] The palmitic acid content in the control group was 5.04±1.22%, while that in the truncated group was 7.09±2.25%, a significant increase of 40.67% (t=3.68, P<0.05).

[0071] The stearic acid content in the control group was 2.92±0.59%, while that in the truncated group was 2.46±0.5%, a decrease of 15.75% (t=2.87, P<0.05).

[0072] The oleic acid content in the control group was 4.7±0.71%, while that in the truncation group was 5.25±1.28%, an increase of 11.70%. There was no significant difference between the two groups (t=1.56, P>0.05).

[0073] The linoleic acid content in the control group was 66.68±3.84%, while that in the sludge-cutting group was 66.89±2.01%, an increase of 0.31%, but there was no significant difference between the two groups (t=1.89, P>0.05).

[0074] The linolenic acid content in the control group was 1.21±0.24%, while that in the skewer group was 0.88±0.14%, a significant decrease of 27.27% (t=5.02, P<0.05).

[0075] The arachidic acid content in the control group was 0.63±0.21%, while that in the dried group was 0.26±0.05%, a decrease of 58.73% (t=6.37, P<0.05).

[0076] The content of carbolic acid in the control group was 0.1±0.02%, while that in the dry group was 0.05±0.01%, a decrease of 50% (t=7.14, P<0.05).

[0077] Table 4. Oil content and oil composition of tung oil seeds compared with those of dried tung oil seeds.

[0078]

[0079] In this embodiment, the target of trunk cutting is a large tree that has already borne fruit. The method of retaining 3 layers of fruiting branches is adopted to achieve the following effects: (i) the tree height is reduced by trunk cutting to facilitate fruit harvesting; (ii) vegetative growth is reduced by reducing apical dominance to promote reproductive growth, thereby improving fruit yield and quality; (iii) the aging and death of lower branches are reduced by trunk cutting and tree rejuvenation is achieved.

[0080] This embodiment investigated the effects of trunk pruning on the growth, leaf morphology, fruit characteristics, and oil quality of *Vernicia fordii* trees by setting up a control group and a trunk pruning treatment. The results showed that trunk pruning had a significant positive regulatory effect on the growth and development of *Vernicia fordii* trees and fruit quality. Specifically:

[0081] (1) After the trunk cutting treatment, the leaf area, leaf perimeter and maximum leaf width of the Ficus microcarpa increased, while the petiole length was significantly shortened. The leaf length, aspect ratio and average width did not change significantly. The increase in the photosynthetic area of ​​the leaves improved the tree's ability to accumulate photosynthetic substances, while the shortened petiole reduced the transport loss of photosynthetic products and optimized the photosynthetic characteristics of the leaves, laying a material foundation for fruit development and oil synthesis.

[0082] (2) In terms of fruit characteristics, stem cutting had no significant effect on the external morphology of individual fruits of *Vernicia fordii*, but it improved the length of the fruit cluster, the weight of the fruit cluster, the weight of 1000 seeds, and the weight of 5 seeds to varying degrees, with the effect on the weight of the fruit cluster being particularly significant. This indicates that stem cutting treatment of *Vernicia fordii* mainly increases yield by promoting the longitudinal growth of the fruit cluster, increasing the overall weight of the fruit cluster and the fullness of the fruit, and significantly improves the yield and quality of *Vernicia fordii* fruit without changing the morphology of individual fruits.

[0083] (3) After the trunk pruning treatment, the *Vernicia fordii* trees exhibited the following characteristics in terms of tree structure and fruiting: the trunk pruning treatment achieved targeted dwarfing of the *Vernicia fordii* trees, with a significant reduction in tree height and number of tree layers compared to the control, a slight decrease in crown width but no significant change, a slight increase in the number of fruiting layers, and a significant increase in the number of fruiting spikes. This indicates that trunk pruning can effectively simplify the tree structure, reduce the ineffective consumption of nutrients on non-fruiting branches, concentrate nutrients to fruiting parts, significantly improve the fruiting capacity of *Vernicia fordii*, and at the same time, dwarfing the tree structure is more conducive to field management and fruit harvesting.

[0084] (4) By cutting back the trunks of vigorous trees, the oil content of *Vernicia fordii* seeds was significantly increased, the content of palmitic acid in the oil components increased substantially, the content of minor components such as stearic acid and arachidic acid decreased, while the proportion of linoleic acid, the core component, remained basically stable. This indicates that while significantly increasing the oil yield of *Vernicia fordii*, the trunk cutting also optimized the composition of the oil components, improved the overall quality of the oil while ensuring the core quality of the oil, and significantly enhanced the economic value of *Vernicia fordii*.

[0085] (5) The treatment of cutting back the trunk and retaining 3 layers of fruiting branches did not have a significant impact on the amount of fruit and the yield of fruit. On the contrary, it promoted the yield and quality. For example, the amount of fruiting branches at the bottom layer increased and the yield of fruit increased; the tree grew well and avoided premature aging; the oil content of the fruit increased slightly and the quality was better than the control.

[0086] In summary, the trunk-cutting treatment is an effective cultivation measure that optimizes the tree structure of *Vernicia fordii*, improves photosynthetic efficiency, increases fruit yield, and enhances oil quality. It can provide important experimental data support for the shaping and pruning methods of *Vernicia fordii* industrial cultivation.

Claims

1. A method for shaping and pruning *Vernicia fordii*, characterized in that: For mature trees that have already borne fruit, the trunk should be cut back, retaining 3 layers of fruiting branches or the tree height should not exceed 4.5 meters.

2. The application of the shaping and pruning method of *Vernicia fordii* as described in claim 1 in optimizing the photosynthetic capacity of *Vernicia fordii*.

3. The application as described in claim 2, characterized in that: The leaf area, leaf circumference, and maximum leaf width of the tung tree can be increased by shaping and pruning methods, while the petiole length can be shortened.

4. The application of the shaping and pruning method of *Vernicia fordii* as described in claim 1 in optimizing the tree structure of *Vernicia fordii*.

5. The application of the shaping and pruning method of *Vernicia fordii* as described in claim 1 in improving the fruiting capacity of *Vernicia fordii*.

6. The application of the shaping and pruning method for *Vernicia fordii* as described in claim 1 in improving the yield and quality of *Vernicia fordii* fruit.

7. The application as described in claim 6, characterized in that: By using shaping and pruning methods, yield can be increased by promoting the longitudinal growth of the fruit bunches, increasing the overall weight of the fruit bunches and the fullness of the fruit, without changing the shape of individual fruits.

8. The application of the shaping and pruning method of *Vernicia fordii* as described in claim 1 in increasing the oil yield of *Vernicia fordii*.

9. The application of the shaping and pruning method of *Vernicia fordii* as described in claim 1 in optimizing the oil composition of *Vernicia fordii*.

Images