Method for dwarfing the fruiting layer of Chinese fir seed orchard

Abstract

The present invention discloses a method for dwarfing the fruiting layer of Chinese fir trees in a seed orchard, belonging to the technical field of timber forest tree cultivation. The method involves pruning the Chinese fir trees in the middle, while retaining branches at the upper and lower parts. This method eliminates the impact of the crown width of the upper and middle layers on external environmental factors such as light in the lower layer by pruning the branches in the middle. This reduces the fruiting layer of the harvested cones, enabling efficient and safe seed collection while minimizing interference with the growth of the Chinese fir mother trees.

Description

Technical Field

[0001] The invention belongs to the technical field of timber forest tree species cultivation, and particularly relates to a method for dwarfing the fruiting layer of a Chinese fir seed orchard. Background Art

[0002] Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is the main afforestation species in southern my country and also the species with the largest afforestation area and stand volume among my country's existing artificial forests. The ninth national forest resources inventory showed that the cultivated area of ​​Chinese fir reached 9.9 million hectares. 2 , with a storage volume of 755 million m 3 , accounting for 25% and 33.3% of the total area and total volume of artificial tree forests in China, respectively, ranking first in both categories. Currently, Chinese fir plantations rely primarily on seed propagation, and high-quality Chinese fir seeds are primarily produced in seed orchards. Thanks to the long-term and unremitting efforts of Chinese fir breeders, my country's Chinese fir breeding research has made gratifying progress, with improved varieties significantly increasing yields and the planted area increasing annually. However, the development of the Chinese fir seed industry still faces several challenges, such as the need to further improve seed yield and quality, insufficient labor for seed orchard operations, and rising input costs. Therefore, how to further improve the construction of Chinese fir seed bases and address the high operating costs and unstable production of improved seeds in Chinese fir seed orchards are key issues facing the Chinese fir seed industry.

[0003] Chinese fir trees are tall. According to surveys, nine-year-old mother trees can reach heights of 8 to 12 meters. The cones in the upper third of some mother trees' crowns are virtually impossible to harvest, making seed collection in seed orchards a dangerous endeavor. Seed collection, pollination, and other management operations require climbing or using ladders, which is inconvenient and poses significant safety risks. This leads to problems such as low seed collection efficiency and incomplete seed collection. Furthermore, my country's forestry areas currently suffer from a labor shortage, with most workers migrating from their hometowns and the forestry industry aging. Few are suitable, willing, or able to climb trees. From an economic perspective, the labor costs of producing improved tree species are generally high.

[0004] Therefore, it is necessary to provide a method for dwarfing the fruiting layer of a Chinese fir seed orchard. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for dwarfing the fruiting layer of trees in a Chinese fir seed orchard. The method is simple and convenient, and while dwarfing the fruiting layer of the Chinese fir seed orchard, it reduces interference with the growth of Chinese fir mother trees.

[0006] A method for preparing lignin micro-nanoparticles using a high-pressure homogenization method, the specific steps are as follows:

[0007] A method for dwarfing the fruiting layer of a Chinese fir seed orchard comprises pruning the Chinese fir in the middle and retaining branches at the upper and lower parts.

[0008] Furthermore, the upper part and the lower part both retain 3, 6 or 9 branches.

[0009] Furthermore, 9 rounds of branches are retained in the upper part.

[0010] Furthermore, three rounds of branches are retained in the lower part.

[0011] Furthermore, after the middle part of the fir is pruned, the germination rate of the seeds in the lower part is increased by 14% to 15%.

[0012] Furthermore, when the middle branches are pruned, the height of the fir is 4 to 9 meters.

[0013] Furthermore, when the middle branches are pruned, the diameter at breast height of the Chinese fir is 6 to 19 cm.

[0014] Furthermore, the fir tree is selected from a fir tree that produces 250 to 1000 cones per tree.

[0015] Furthermore, the fir tree is selected from a fir tree that produces 250 to 500 cones per tree.

[0016] Furthermore, the north-south crown width of the fir tree is larger than the east-west crown width.

[0017] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0018] (1) The present invention performs middle pruning on trees in a Chinese fir seed garden, thereby eliminating the influence of the upper and middle parts on the lower part, avoiding natural pruning, reducing the fruiting layer, and reducing the difficulty of seed collection.

[0019] (2) The present invention preserves the apical dominance and photosynthesis of the top, improves the conditions of light, moisture and ventilation in the lower part of the tree, changes the nutrition in the lower part, reduces the fruiting layer, and preserves the mother tree, which brings a lot of convenience to the tending management in the operation and the harvesting of the cones in the later stage, improves the safety of the harvesting process and the sustainable development of the seed garden.

[0020] (3) The present invention changes the distribution of nutrients and hormones in the tree by pruning, which not only increases the fruit yield but also improves the quality of the fruit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the middle part of the truncated branch of the present invention;

[0022] Figure 2 The basic growth conditions of the Chinese fir plant during pruning according to the present invention;

[0023] Figure 3 The tree height growth change of Chinese fir measured by the present invention;

[0024] Figure 4 The growth change of diameter at breast height of Chinese fir measured by the present invention;

[0025] Figure 5 The growth change of the east-west crown width of the Chinese fir measured by the present invention;

[0026] Figure 6 The growth change of the north-south crown width of Chinese fir measured by the present invention;

[0027] Figure 7 It is the fruiting condition of the upper part after pruning;

[0028] Figure 8 It is the fruiting condition of the lower part after pruning;

[0029] Figure 9 This is a box plot of the number of fir cones of the present invention;

[0030] Figure 10 This is a box plot of Chinese fir germination rate of the present invention;

[0031] Figure 11 This is a boxplot of the thousand-grain weight of Chinese fir of the present invention;

[0032] Figure 12 This is a box plot of the seed yield rate of Chinese fir of the present invention;

[0033] Figure 13 This is the heat map of the correlation coefficients of the lower layer shapes after pruning. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to specific embodiments.

[0035] The Chinese fir used in the following examples was selected from the 4th generation germplasm resource bank of the Yangkou State Forest Farm in Fujian Province.

[0036] Example 1

[0037] 1. The method of dwarfing the fruiting layer of Chinese fir seed garden is as follows:

[0038] Three Chinese fir trees were randomly selected (each with 283, 522, and 978 cones, and plant heights of 6.24m, 7.93m, and 8.48m, respectively), and named No. 1 (283 cones, 6.24m), No. 2 (522, 7.93m), and No. 3 (978, 8.48m), respectively. The north-south crown width was larger than the east-west crown width. The branches were pruned in the middle, and 3, 6, or 9 rounds of branches were retained in the upper and lower orthogonal designs. The orthogonal design table is shown in Table 1 below. Three Chinese fir trees were randomly selected without pruning as controls. The pruning diagram is shown in Figure 1 shown.

[0039] Table 1 Orthogonal design table of different fir pruning treatments

[0040] serial number Number of branches retained in the upper part Number of branches retained at the lower part 1-1 6 6 1-2 9 3 1-3 3 9 2-1 9 6 2-2 3 3 2-3 6 9 3-1 9 9 3-2 3 6 3-3 6 3

[0041] 2. Determination of growth indicators

[0042] In July and November 2021 and July and November 2022, the growth of the selected Chinese fir trees was investigated before and after pruning, including tree height, diameter at breast height, and crown width in the east, west, south, and north directions, and their growth was calculated. After the central part of the Chinese fir plants was pruned in July 2021, new branches grew in the middle of the trunk during the growth period of the Chinese fir in 2022. In July 2022, the new branches were pruned and their number, fresh weight, length, base diameter and other indicators were counted. The results are as follows Figures 2 to 6 shown.

[0043] Figure 2 This shows the basic growth of Chinese fir plants during pruning according to the present invention. As can be seen from the figure, at the time of pruning, the test Chinese fir plants reached a height of 4 to 9 meters, with a diameter at breast height (DBH) ranging from 6 to 19 cm. Comparing the three Chinese fir plants, the north-south crown width was larger than the east-west crown width. Significant differences were observed among the three Chinese fir plants in tree height, DBH, east-west, and north-south crown widths.

[0044] Figure 3 The present invention measures the growth changes in the height of Chinese fir trees. Growth 1 represents the change from July of the year when the branches were pruned to November of the current year; Growth 2 represents the change from November of the current year to July of the second year; and Growth 3 represents the change from July of the second year to November of the second year. As can be seen from the figure, there are significant differences in the three growths in tree height among the three Chinese fir trees. Among them, No. 2 grows the fastest, and No. 1 grows slower. In Growth 1, the tree height growth of the three pruned groups is greater than that of the control, while Growth 2 and Growth 3 are less than that of the control. This is because Growth 1 was only four months away from pruned, and the damage to the tree caused by pruned meant that the nutrients accumulated on the branches were mainly used to supply the growth of the tree. Afterwards, the hormone levels and nutrient status of the pruned groups needed a certain amount of time to adjust and recover.

[0045] Figure 4 The growth changes of the diameter at breast height of Chinese fir measured in the present invention are shown in the figure. As can be seen from the figure, only the growth rate of diameter at breast height No. 2 shows significant differences among the three types.

[0046] Figure 5 The growth changes of the east-west crown width of the Chinese fir measured by the present invention are as follows: Figure 6 The growth variation of the north-south crown width of Chinese fir measured by the present invention is as follows: Figure 5 、 6The results show that the 2nd cutting group had greater growth in both east-west and north-south crown width than the control group. In the north-south crown width growth, the 1st cutting group had the greatest difference from the control group, with the north-south crown width growth of the cutting group being 8 times that of the control group, while the 2nd and 3rd cutting groups had north-south crown width growth of 1 to 3 times that of the control group.

[0047] In summary, by comparing the three growth amounts, it can be found that in terms of tree height, breast diameter, east-west crown width, and north-south crown width, the growth amount 2 is the largest. This is because the Chinese fir plants experienced a growing period from November to July of the following year, and the growth of the plants slowed down from July to November due to climate, physiological habits and other reasons.

[0048] 3. Determination of seed shape

[0049] For the lower part of each test tree and control tree, cones were collected by single-plant layering according to rounds 1-3, 4-6, and 7-9, while cones were collected by division from the upper part of each test tree and control tree. In accordance with the "Regulations for Inspection of Forest Seeds" (GB2772-1999), the germination rate, quality, astringent seed rate, empty seed rate, and thousand-seed weight were measured. The calculation method for the index measurement is as follows. The results are shown in Table 2. Figure 7 and Figure 8 shown.

[0050] (1) Yield shape (YT): includes two indicators: number of cones (NC, pieces) and total seed weight (TSW, g).

[0051] (2) Seed shape representation (SPT): including seed length (SL, mm), seed width (SW, mm), seed area (SA, mm 2 ) and species shape index (SSI, mm).

[0052]

[0053] The length and width of the cones were measured three times with a vernier caliper and the average value was taken.

[0054] (3) Seed germination characteristics (SGC) determination: including two indicators: germination rate (GR, %) and germination potential (GE, %).

[0055]

[0056]

[0057] (4) Seed quality traits (SET) determination: including 1000-grain weight (TGW, g): the weight of 1000 pure seeds in the air-dried state, quality index (ED, %), empty seed rate (ESR, %) and astringent seed rate (DSR, %);

[0058]

[0059]

[0060]

[0061] (5) Determination of coefficient of variation (CV, %):

[0062]

[0063] In the formula, CV is the coefficient of variation, σ is the standard deviation, is the average.

[0064] (6) Heritability (h 2 ) determination:

[0065]

[0066] Where h 2 is the broad-sense heritability, and F is the F value in variance analysis.

[0067] (7) The formula for seed yield is as follows:

[0068]

[0069] Table 2 Changes in the number of Chinese fir cones after two years of different pruning treatments

[0070]

[0071] Table 2 shows the changes in the number of Chinese fir cones after two years of different pruning treatments. Figure 7 The fruiting condition of the upper part after pruning. Figure 8 The fruiting condition of the lower part after pruning is shown in Table 2. Figure 7 and 8 It can be seen that Figure 2As can be seen, due to the extremely small number of cones on the upper part of No. 2, no variance analysis was performed on it. The number of cones on the upper part of No. 1 and No. 3 pruning branches in the year after pruning was converted according to pruning type (number of cones / number of rounds, the same below), and then a two-way ANOVA was performed on the pruning method. The results showed no significant difference in the upper part of No. 2 (p = 0.95), nor were there significant differences among the four pruning methods: 3, 6, 9 rounds, and the control (p = 0.50). A two-way ANOVA was performed on the number of cones on the upper part of No. 1 and No. 3 pruning branches in the year after pruning. The results showed that there was no significant difference in the upper part of No. 2 (p = 0.83), nor was there a significant difference between the different pruning methods (p = 0.81). A two-way ANOVA of the number of cones in the upper part of No. 1 and No. 3 before and after pruning was conducted. The results showed that there was a significant difference between the two years for No. 1 (p = 0.01), but no significant difference between the pruning methods (p = 0.59). There were significant differences in the number of cones in the upper part of No. 3 between the two years and both the pruning methods (p = 1.27E-05, p = 0.000168). For No. 1, there was a significant difference in the number of cones in the upper part before and after pruning for two years, but no significant difference between the pruning methods. However, there were significant differences in the number of cones in No. 3 between the two years and both the pruning methods.

[0072] The number of lower cones before and after pruning did not differ significantly across the three pruning methods or the different pruning methods. Before pruning, there was no significant difference in the number of lower cones among the three Chinese fir trees (p = 0.12), nor among the different pruning methods (p = 0.50). After pruning, there was no significant difference among the three Chinese fir trees or among the different pruning methods (p = 0.09, p = 0.49). For No. 1, the number of lower cones did not differ significantly before and after pruning, regardless of pruning method (p = 0.17, p = 0.33). There was no significant difference between No. 2 and No. 3 before and after pruning (p = 0.19, p = 0.33), nor among the pruning methods (p = 0.59, p = 0.51). Therefore, before pruning, the number of cones was primarily concentrated in the middle of the tree. Pruning primarily increased the number of cones in the upper part of the tree, while having no significant effect on the number of lower cones.

[0073] Across the different pruning treatments, only the upper branches of Chinese fir trees with nine whorls of cones produced cones in the year of pruning. There were significant differences among the three types of trees. The low-fruiting trees had the most cones, with 88, while the medium-fruiting and high-fruiting trees had 3 and 6 cones, respectively. The upper branches with three and six whorls of cones both had zero cones. The lower branches with three whorls of cones produced the least cones in the year of pruning. The lower branches with nine whorls of cones had 289 cones, while the medium-fruiting and low-fruiting trees had 1 and 5 cones, respectively. The number of cones in the lower branches was greater than that in the upper branches in the year after pruning. The following year, the medium-fruiting trees produced 15 cones, with the remaining pruned trees and the control trees producing no cones. Among the high-fruiting and low-fruiting trees, the number of cones in the upper branches was higher in the order of nine whorls, higher in the order of six whorls, and higher in the order of three whorls. The number of cones in the nine whorls of branches retained was greater than that in the upper nine whorls of the control group, while the number of cones in the lower nine whorls of the control group was greater than that in the pruned group. The following year after pruning, the number of cones in the upper branches was greater than that in the lower branches. The average growth rate of cones in both low- and high-fruiting varieties was higher than that in the control group, reaching a maximum of 6833.33%. The medium-fruiting variety had the lowest growth rate and a negative growth rate, with almost no fruiting. This initial performance may be due to the poor genetic stability of the medium-fruiting variety, making it unsuitable for dwarfing experiments.

[0074] 4. Growth of new branches in the middle of the trunk of Chinese fir after pruning

[0075] Table 3 Growth of new branches in the middle of the trunk of Chinese fir after pruning

[0076]

[0077] Table 3 shows the growth of new branches in the middle trunk of Chinese fir trees after pruning. As can be seen, after pruning, there were significant differences in the total number, fresh weight, fresh weight per branch, length, and base diameter of new branches in the middle trunk between trees with medium fruiting capacity, low fruiting capacity, and high fruiting capacity. In all cases, the medium fruiting capacity had the highest number of new branches, while the low fruiting capacity had the lowest. The total number and fresh weight per branch of new branches in trees with medium fruiting capacity were three times that of those with low fruiting capacity, while the length and base diameter of each branch were twice as high. The total fresh weight of new branches reached 34 times that of those with low fruiting capacity. This indicates that trees with medium fruiting capacity have more nutrients in the middle trunk and a stronger ability to sprout branches. Furthermore, as shown in Table 2, trees with medium fruiting capacity rarely produce fruit, with nutrients being used more for sprouting new branches. Therefore, appropriate "bud removal" measures should be adopted to remove excess buds and minimize the consumption of nutrients for new branch sprouting.

[0078] 5. Variance analysis of the shapes of the lower fruiting layer of Chinese fir in the year of pruning

[0079] The results of two-way variance analysis without interaction between the various indicators of the lower fruiting layer of Chinese fir in the year of pruning and the pruning method are shown in Table 4. Figure 7 and Figures 9-12 shown.

[0080] Table 4 Two-way ANOVA of various indices of the lower fruiting layer of Chinese fir in the year of pruning and pruning methods

[0081]

[0082]

[0083] Table 4 shows the two-way ANOVA of various indices of the lower fruiting layer of Chinese fir trees in the year of pruning and the pruning method. As can be seen from the table, there were no significant differences in the number of cones, dry weight of single fruit, seed yield, empty seed rate, astringent seed rate and quality among the three Chinese fir trees (p>0.05). However, after multiple comparisons, it was found that the dry weight of single fruit of the tree with a large fruit yield (No. 3) was significantly different from that of the tree with a small fruit yield (No. 1); the differences in cone width, 1000-grain weight and seed width reached a significant level (0.01<p<0.05); the differences in single fruit fresh weight, cone length, seed area, seed length, seed shape index, seed emergence rate and germination potential all reached an extremely significant level (p<0.01). Multiple comparisons revealed significant differences in cone width between varieties with high and medium seed production (No. 2); significant differences in 1000-seed weight, seed area, and seed width between varieties with medium and low seed production; and significant differences in single fruit fresh weight, cone length, germination potential, seed length, seed shape index, and seed emergence rate between varieties with high and low seed production, and between varieties with medium and low seed production. Only germination rate showed a highly significant difference between the different pruning methods (retaining three, six, or nine whorls at the bottom, or no pruning), indicating that different pruning methods significantly affect germination rate and that pruning can alter seed quality.

[0084] Figure 7 The figure shows the upper fruiting situation after pruning. The figure shows that the number of cones before pruning varied significantly among the three Chinese fir trees. After pruning, the average number of cones in the high-fruiting trees was still greater than that in the low-fruiting and medium-fruiting trees, but the difference was not statistically significant. This indicates that pruning reduced the difference in cone yield. The germination rate of the medium-fruiting trees shifted from the highest before pruning to the lowest after pruning. This may be because the medium-fruiting trees experienced significant increases in growth indicators such as height, diameter at breast height, and crown width after pruning, resulting in insufficient nutrients for seed development. The low-fruiting trees, on the other hand, experienced smaller increases in these growth indicators, allowing them to absorb sufficient nutrients for seed development. The 1000-grain weight trends among the three different fruiting types were consistent with those before pruning, with the medium-fruiting trees having the highest 1000-grain weight. The seed emergence rate among the three types varied significantly, with the high-fruiting trees having the highest seed emergence rate. This is because the high-fruiting trees had significantly greater cone length, width, and dry weight than the low-fruiting and medium-fruiting trees.

[0085] Figure 9 This is a box plot of the number of fir cones of the present invention, Figure 10 This is a box plot of Chinese fir germination rate of the present invention; Figure 11 This is the box plot of the thousand-grain weight of Chinese fir of the present invention, Figure 12 The box plot of the seed yield rate of Chinese fir of the present invention; pruning methods 1, 2, 3, and 4 respectively represent retaining 3 whorls of branches, 6 whorls of branches, 9 whorls of branches and no pruning at the bottom. Figures 9-12 It can be seen that the number of cones, germination rate, and seed production rate of the control (i.e., no pruning) were all higher than the average level of the pruning group. This is because pruning causes damage to the plant, which requires a certain amount of time to recover. Only the germination rate showed significant differences between the different pruning methods. The germination rate was the lowest when three whorls of branches were retained at the bottom. Because most of the branches and leaves were cut off, the remaining branches and leaves had limited nutrient transport and could not meet the nutritional level required by the plant. The germination rate was the highest when six whorls of branches were retained at the bottom because the energy produced and transported by the retained branches and leaves reached a dynamic balance with the nutrients required for seed development.

[0086] 6. Analysis of the shapes of the lower fruiting layer of Chinese fir in the year after pruning

[0087] The results of two-way ANOVA without interaction between the indices of the lower fruiting layer of Chinese fir and the pruning method in the year after pruning are shown in Table 5.

[0088] Table 5 Two-way ANOVA of various indices of the lower fruiting layer of Chinese fir and pruning methods in the year after pruning

[0089]

[0090]

[0091]

[0092] Table 5 presents a two-way analysis of variance for various parameters of the lower fruiting layer of Chinese fir trees in the year following pruning and for pruning methods. The table shows that significant differences were found in single-fruit dry weight and germination potential among the three Chinese fir species, while extremely significant differences were found in empty seed rate, quality, and germination rate. No significant differences were found in other parameters. Multiple comparisons revealed significant differences in single-fruit dry weight, cone length, and empty seed rate between medium and low fruit yields, while significant differences were found in germination potential, quality, and germination rate between low and medium and high fruit yields. Only the empty seed rate showed significant differences among the different pruning methods; no significant differences were found in other parameters.

[0093] 7. Analysis of the shapes of the upper fruiting layer of Chinese fir two years after pruning

[0094] Table 6 Related indicators of cones and seeds in the upper part of Chinese fir in the year of pruning

[0095]

[0096]

[0097] Table 7 Related indicators of cones and seeds in the upper part of Chinese fir in the year after pruning

[0098]

[0099]

[0100] Table 6 shows the relevant indicators of upper cones and seeds of Chinese fir trees in the year of pruning. As can be seen from the table, pruning had a certain impact on the characteristics of both upper cones and seeds. In the year of pruning, only the test tree No. 1, which retained nine whorls of branches (1-2), and the control tree produced fruit. The seed and cone yield, phenotypic traits, and germination traits of the test tree No. 1-2 were higher than those of the control tree. After pruning, only the test tree No. 2, which retained nine whorls of branches (2-1), produced fruit; the control tree also did not produce fruit. Compared with No. 2 before pruning, the seed and cone traits of No. 2-1 were lower than those before pruning. After pruning, only the test tree No. 3, which retained nine whorls of branches (3-1), and the control tree produced fruit. The seed and cone traits were also lower than those of the control tree. This shows that, based on observations in the year of pruning, the pruning method that retains nine whorls of branches is more suitable for upper pruning, and the seed and cone traits of the branches with low fruit yields are significantly improved after pruning.

[0101] Table 7 shows the relevant indicators of cones and seeds in the upper part of Chinese fir trees in the year following pruning. As can be seen, all seed and cone characteristics of pruning 1 were higher than those of the control. Pruning 3 also showed higher 1000-grain weight, seed phenotype, and germination rate, while cone phenotype, seed yield, and seed emergence were lower than those of the control. Therefore, pruning can improve seed quality, but the results vary among shamu trees.

[0102] 8. Two-way ANOVA of the upper and lower indicators and the different years before and after pruning

[0103] Table 8 Two-way ANOVA of the upper and lower indicators and the different years before and after pruning

[0104]

[0105] Table 8 presents a two-way ANOVA analysis of various parameters in the upper and lower fruiting layers and in different years before and after pruning. The table shows that the two-way ANOVA analysis of the upper and lower fruiting layers and in different years before and after pruning (before pruning, the year of pruning, and the year after pruning) showed significant differences in the empty and astringent grain rates of the upper fruiting layer among the three Chinese fir trees. Multiple comparisons revealed significant differences in the empty grain rate between No. 1 and No. 2, and a significant difference in the astringent grain rate between No. 1 and No. 3. Significant differences were also found in the seed shape index and empty grain rate of the lower fruiting layer among the three trees. Multiple comparisons revealed significant differences in the seed shape index between No. 1 and No. 3, and significant differences in the empty grain rate between No. 1 and No. 2 and No. 3. With the exception of the astringent grain rate, all other traits of the upper fruiting layer showed significant differences between different years. Multiple comparisons revealed significant differences in 1000-grain weight, quality rating, and germination rate between before pruning and the year of pruning. Seed area, seed length, seed width, and seed shape index showed significant differences before pruning, the year of pruning, and the year after pruning. Germination potential also showed significant differences before pruning, the year of pruning, and the year after pruning. The seed area, seed length, seed width, germination potential, and empty seed rate of the lower fruiting layer also showed significant differences between different years. Multiple comparisons revealed that seed area, seed length, and seed width showed significant differences before pruning, the year of pruning, and the year after pruning. Germination potential also showed significant differences before pruning, the year of pruning, and the year after pruning. The empty seed rate also showed significant differences between the year of pruning and the year after pruning. Therefore, for both the upper and lower fruiting layers, all indicators showed significant differences between Chinese fir trees and between different years. Furthermore, the differences between different years in the upper layer were greater than those in the lower layer.

[0106] 9. Correlation analysis between cone and seed shape in the lower layer of Chinese fir after pruning

[0107] In order to reveal the correlation between the various traits after pruning, the correlation analysis of 16 seed trait indices after pruning was carried out. The results are as follows: Figure 13 shown.

[0108] Figure 13 This is a heat map of correlation coefficients for various shapes in the lower layer after pruning. The figure shows that the number of cones after pruning is significantly and extremely significantly positively correlated with seed yield, cone dry weight, cone width, and seed emergence rate, and extremely significantly negatively correlated with empty seed rate. Germination rate is extremely significantly positively correlated with germination potential and seed quality, and significantly and extremely significantly negatively correlated with seed area, seed length, and seed shape index. This indicates that smaller seeds have higher germination rates. Thousand-grain weight is extremely significantly positively correlated with seed area, seed width, and seed length. This indicates that larger seed area and fuller seeds are associated with higher thousand-grain weight. This indicates that seed phenotypic indicators are significantly correlated with seed quality indicators.

[0109] 10. Comprehensive evaluation of the quality of cones and seeds in the lower layer of Chinese fir with different pruning methods

[0110] (1) A principal component analysis was conducted on 16 traits of the lower cones and seeds of three types of Chinese fir with different pruning treatments observed for two consecutive years. The results are shown in Table 9.

[0111] Table 9 Principal component analysis of seed characteristics in the undercrop layer of Chinese fir two years after pruning

[0112]

[0113]

[0114] Table 9 shows the principal component analysis of seed traits in the understory of Chinese fir canopies two years after pruning. Three principal components were extracted for cone and seed traits in the year of pruning, based on the principle of eigenvalues ​​greater than 1. The cumulative contribution rate was 85.72%, indicating that these three principal components strongly reflect information about cones and seeds. The first principal component had an eigenvalue of 6.28 and a contribution rate of 39.24%. The eigenvectors for 1000-seed weight, seed area, seed length, and seed width had high loadings, indicating that the first principal component reflects phenotypic traits of Chinese fir seeds. The second principal component had an eigenvalue of 5.67 and a contribution rate of 35.42%. The eigenvectors for single-seed dry weight, cone length, and cone width had high loadings, indicating that the second principal component reflects phenotypic traits of Chinese fir cones. The third principal component had an eigenvalue of 1.77 and a contribution rate of 11.06%. The eigenvectors for quality and empty seed rate had high loadings, indicating that the third principal component reflects Chinese fir seed quality traits.

[0115] (2) Substituting the 16 cone and seed trait indices into the three principal components, we obtained three comprehensive index scores, represented by F1, F2, and F3, respectively. Using the proportion of the total contribution of each principal component as the weight coefficient (0.46, 0.41, and 0.129), we calculated the comprehensive score and ranking of the lower cone and seed quality traits for each tree. The results are shown in Table 10.

[0116] Table 10 Comprehensive evaluation of various shapes of the lower canopy of Chinese fir trees in the year of pruning

[0117]

[0118]

[0119] Table 10 presents a comprehensive evaluation of various fruit shapes in the lower canopy of Chinese fir trees in the year of pruning. The table shows that the average overall scores for the three types of pruning groups were 3 > 2 > 1, and the pruning group with type 3 ranked higher than the control. The highest ranking was 3-1, indicating a high fruit yield with nine whorls of branches remaining in the upper, middle, and lower parts of the Chinese fir plant.

[0120] (3) The principal component analysis method was used to analyze the cone and seed traits in the year after pruning and four principal components were extracted, with a cumulative contribution rate of 94.31%. The eigenvalue of the first principal component was 8.00, with a contribution rate of 49.98%. The loads of seed length, astringent seed rate, quality and germination rate in the eigenvector were relatively high, indicating that the first principal component mainly reflected the quality traits of Chinese fir seeds; the eigenvalue of the second principal component was 4.17, with a contribution rate of 26.08%. The loads of seed width, seed yield and cone number in the eigenvector were relatively high, indicating that the second principal component mainly reflected the yield traits of Chinese fir; the eigenvalue of the third principal component was 1.67, with a contribution rate of 10.37%. The load factors of cone width and cone dry weight in the eigenvector were relatively high, indicating that the third principal component mainly reflected the phenotypic traits of Chinese fir cones; the eigenvalue of the fourth principal component was 1.26, with a contribution rate of 7.88%. The load factors of empty seed rate and germination rate in the eigenvector were relatively high, indicating that the fourth principal component and the first principal component together reflected the seed quality traits.

[0121] The comprehensive index scores (F1, F2, F3, F4) and weight coefficients (0.53, 0.28, 0.11, 0.08) were calculated according to the formula, and the comprehensive scores and rankings of the lower cone and seed quality traits of each tree were obtained. The results are shown in Table 11.

[0122] Table 11 Comprehensive evaluation of various fruit shapes in the lower canopy of Chinese fir trees in the year after pruning

[0123] serial number F1 F2 F3 F4 Comprehensive score Sorting 1-1 -0.042 1.596 -0.164 -1.128 0.31 3 1-2 1.683 0.309 -0.853 1.352 1.00 1 1-3 0.296 -1.316 -0.739 -1.528 -0.42 7 CK1 0.610 0.807 0.593 -0.568 0.56 2 2-3 -1.861 0.516 -1.077 0.745 -0.90 8 3-1 -0.440 -0.813 0.745 -0.039 -0.38 6 3-2 -0.031 -1.021 -0.373 0.524 -0.30 5 CK3 -0.215 -0.078 1.869 0.643 0.12 4

[0124] Table 11 presents a comprehensive evaluation of various fruit shapes in the lower canopy of Chinese fir trees the year after pruning. As can be seen, three trees in the lower canopy failed to produce fruit the year after pruning, including two with moderate fruit production and one with high fruit production. The control, which also produced moderate fruit, also failed to produce fruit. The average overall scores for the three pruning types were 1 > 3 > 2. The highest ranking was 1-2, indicating a Chinese fir plant with low fruit production, retaining nine whorls of branches in the upper and middle sections and three whorls in the lower sections.

[0125] The combined scores for cone and seed traits at the lower part of each plant varied significantly between the two years after pruning. This is because the cones in the year of pruning were only four months old. The damage caused by pruning to the Chinese fir plant requires time to recover, and nutrients need to be redistributed. Therefore, continuous observation of cone and seed traits over several years is necessary to ensure more accurate and reliable test results.

[0126] In summary, plants with small fruiting amounts are more suitable for dwarfing pruning, and the best pruning method is to retain 9 rounds on the upper part and 3 rounds on the lower part.

Claims

1. A method for dwarfing the fruiting layer of a Chinese fir seed orchard, characterized in that: The fir is pruned at the middle, and branches are retained at both the upper and lower parts; 9 whorls of branches are retained at the upper part, and 3 whorls of branches are retained at the lower part; when the fir is pruned at the middle, the height of the fir is 4 to 9 meters, and the diameter at breast height of the fir is 6 to 19 cm; the fir is selected to have a fruit yield of 250 to 1000 cones per tree.

2. The method for dwarfing the fruiting layer of a Chinese fir seed orchard according to claim 1, characterized in that: After the middle part of the fir is pruned, the germination rate of the seeds at the lower part is increased by 14% to 15%.

3. The method for dwarfing the fruiting layer of a Chinese fir seed orchard according to claim 1, characterized in that: The fir trees selected are those with a fruit yield of 500 cones per tree.

4. The method for dwarfing the fruiting layer of a Chinese fir seed orchard according to claim 1, characterized in that: The north-south crown width of the fir tree is larger than the east-west crown width.

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