A method for regulating nutrient elements in fir leaves

Abstract

This invention discloses a method for regulating nutrient elements in Chinese fir leaves, belonging to the technical field of timber tree cultivation. This method involves pruning the Chinese fir trees at the center, retaining branches at both the upper and lower ends. The spacing between rows of Chinese fir trees is 3m x 3m. By pruning the Chinese fir trees at the center, this method improves light, water, and ventilation conditions, altering the distribution of nutrients within the tree. This alters the distribution of the nutrient elements N, P, and K in the leaves, enhancing the plant's stress resistance and facilitating later care and harvesting of cones.

Description

Technical Field

[0001] The invention belongs to the technical field of timber tree species cultivation, and particularly relates to a method for regulating nutrient elements in fir leaves. 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. At present, Chinese fir plantations mainly rely on seed propagation, and high-quality Chinese fir seeds are mainly produced in seed gardens. After long-term and unremitting efforts of Chinese fir breeders, my country's Chinese fir breeding research has made gratifying progress, with significant results in increasing the yield of improved varieties, and the planting area has increased year by year. However, in the development of the Chinese fir seed industry, there are still problems such as high operating costs of Chinese fir seed gardens and unstable production of improved varieties.

[0003] Leaves are essential organs for photosynthesis and transpiration in most plants, and tree leaf analysis has become a promising tool for forestry nutritional diagnosis. However, there are currently few reports on the correlation between nutrient elements and chlorophyll content in leaves after pruning. Nitrogen, phosphorus, potassium, and carbon play important roles in plant growth and development. Carbon is the primary component of plant dry matter, while nitrogen, phosphorus, and potassium are essential minerals for plant growth and have a significant impact on plant yield and quality. Studies have shown that pruning significantly affects nitrogen and potassium content in young Phoebe bournei leaves, while having little effect on phosphorus content. Pruning not only improves the carbon to nitrogen ratio of mango and citrus leaves but also promotes an increase in the carbon to nitrogen ratio of pecan, thereby promoting flowering. Pruning can also improve photosynthetic efficiency and photosynthetic pigment content. Research has shown that increasing nitrogen, phosphorus, and potassium content not only increases fruit yield and quality but also has a certain positive effect on forest yield and quality.

[0004] Therefore, it is urgent to provide a method for regulating the nutrient elements of Chinese fir leaves. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for regulating the nutrient elements of Chinese fir leaves. The method is simple and convenient, and changes the conditions of light, moisture and ventilation of the tree, thereby changing the distribution of nutrients in the tree, thereby changing the nutrient elements N, P and K in the leaves, enhancing the plant's resistance to stress, and bringing convenience to the later care management and harvesting of cones.

[0006] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for regulating nutrient elements in fir leaves comprises pruning the fir in the middle and retaining branches at the upper and lower parts, wherein the spacing between rows of the fir trees is 3m×3m.

[0008] Furthermore, the nutrient elements are N, P and K.

[0009] Furthermore, the concentration of nitrogen in the fir needles is 10 to 16 g / kg.

[0010] Furthermore, the concentration of P element in the fir needles is 1 to 2 g / kg.

[0011] Furthermore, the concentration of K element in the fir needles is 8 to 11 g / kg.

[0012] Furthermore, the upper part and the lower part both retain 3, 6 or 9 branches.

[0013] Furthermore, 9 rounds of branches are retained in the upper part.

[0014] Furthermore, three rounds of branches are retained in the lower part.

[0015] Furthermore, the fir tree is selected from a fir tree that produces 250 to 1000 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 improves the light, moisture and ventilation conditions of the tree by pruning the middle part of the fir, thereby changing the distribution of nutrients in the tree, thereby changing the nutrient elements N, P and K in the leaves, enhancing the stress resistance of the plant, and bringing convenience to the later care management and cone harvesting.

[0019] (2) After the pruning process of the present invention, the concentration of N in the fir needles is 10-16 g / kg, the concentration of P is 1-2 g / kg, and the concentration of K is 8-11 g / kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the positions of the upper, middle and lower layers of Chinese fir wood according to the present invention;

[0021] Figure 2 It is the box plot of N content at different measurement times of the present invention;

[0022] Figure 3 It is the box plot of P content at different measurement times of the present invention;

[0023] Figure 4 It is the box plot of K content at different measurement times of the present invention;

[0024] Figure 5 It is the box plot of C content at different measurement times of the present invention;

[0025] Figure 6 It is the box plot of the ratio of N / C at different measurement times of the present invention;

[0026] Figure 7 It is the box plot of the ratio of P / C at different measuring times of the present invention;

[0027] Figure 8 It is the box plot of the ratio of K / C at different measurement times of the present invention;

[0028] Figure 9 The box plot of the ratio of N / P at different measurement times of the present invention;

[0029] Figure 10 is the change of chlorophyll content in the lower part after pruning;

[0030] Figure 11 is the chlorophyll content of reproductive branches and nutrient branches;

[0031] Figure 12 This is the heat map of the correlation coefficients of nutrients in the upper reproductive branches in the year after pruning;

[0032] Figure 13 This is the heat map of the correlation coefficients of nutrient elements in the upper nutrient branches in the year following the pruning;

[0033] Figure 14 This is the heat map of the correlation coefficients of the nutrient elements in the lower nutrient branches before pruning;

[0034] Figure 15 This is a heat map of the correlation coefficients of nutrient elements in the lower nutrient branches after pruning. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific embodiments.

[0036] 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.

[0037] Example 1

[0038] The methods for regulating the nutrient elements of Chinese fir leaves are as follows:

[0039] 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, 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. Among them, the experimental site adopted artificial strip land preparation with a belt width of 1.2m, a hole size of 0.6m×0.4m×0.4m, and a plant spacing of 3m×3m. Three Chinese fir trees were randomly selected without pruning as a control. The pruning diagram is shown in the following table. Figure 1 shown. Figure 1 This is a schematic diagram of the positions of the upper, middle and lower layers of Chinese fir wood according to the present invention;

[0040] Table 1 Orthogonal design table of different fir pruning treatments

[0041] 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

[0042] Example 2

[0043] 1. Changes in nutrient elements in leaves of Chinese fir plants

[0044] When pruning in July 2021, 1 to 2 whole branches were selected from the lower fruiting layer of each test tree in the east, south, west and north directions. In July of the following year after pruning (July 2022), for the upper fruiting layer, 3 reproductive branches and 3 nutrient branches of each test tree were randomly selected as samples; and for the lower fruiting layer, 1 to 2 whole branches were selected from each test tree in the 1-3, 4-6 and 7-9 rounds and east, south, west and north directions respectively. In November of the following year after pruning (November 2022), for the upper fruiting layer, 3 whole branches from 4 test trees of each asexual line were randomly selected as samples; and for the lower fruiting layer, the collection method was the same as in July 2022. The selected branches were all in good growth and free of diseases and insect pests.

[0045] The nitrogen content in the solution was determined by a Kjeldahl nitrogen analyzer; the phosphorus content in the solution was determined by the molybdenum antimony colorimetric method on an ultraviolet spectrophotometer; the potassium content in the solution was determined by a flame atomic absorption spectrophotometer; and the organic carbon content in the leaves was determined by the potassium dichromate method.

[0046] 2. Determination of N, P, K and C contents in lower leaves of Chinese fir before and after pruning

[0047] The nutrient content of the lower leaves of the three fruiting types was compared before pruning and in July and November of the year after pruning. The results are shown in Table 2 and Figures 2 to 5 shown.

[0048] Table 2 Comparison of nutrient element content in lower leaves of Chinese fir before and after pruning

[0049]

[0050]

[0051] The data in the table are mean ± standard deviation. Different lowercase letters in the same column indicate differences at the 0.05 level. The same letters indicate no significant differences, while different letters indicate significant or extremely significant differences.

[0052] Table 2 compares the nutrient content of the lower leaves of Chinese fir before and after pruning. As shown in the table, before pruning, there were no significant differences in P, K, and C content among the three clones, while N content differed significantly between clones 1 and 2, with clone 2 having the highest N content, at 15.36 g / kg. In July of the following year after pruning, there were still no significant differences in P and C content among the three clones, but there were significant differences in K content between clones 2, 1, and 3, with the K content in clone 3 being 1.8 times that of clone 1. There were also significant differences in N content between clone 2, 1, and 3, with clone 3 having the highest N content, at 16.55 g / kg. In November of the following year after pruning, there were no significant differences in K content among the three clones, but there were significant differences in N and C content between clones 1 and 3, and there was a significant difference in P content between clones 2 and 3. After pruning, there were no significant differences in N, P, K, or C content among the three pruning groups and the control.

[0053] Figure 2 It is the box plot of N content at different measurement times of the present invention; Figure 3 It is the box plot of P content at different measurement times of the present invention; Figure 4 It is the box plot of K content at different measurement times of the present invention; Figure 5 It is a box plot of the C content at different measurement times of the present invention; in the figure, measurement times 1, 2, and 3 represent July 2021 before pruning, July 2022 after pruning, and November 2022 after pruning, respectively. As can be seen from the figure, there are significant differences in N and C content before and after pruning, and no significant changes in P and K content. After pruning, the content of N, P, K and C elements were all improved, among which the average growth rate of N content was the highest, reaching 19.6%. This shows that pruning has a promoting effect on the absorption of N by leaves; the difference in C content is the most significant, indicating that pruning improves photosynthesis in the lower part and increases the fixation of CO2 in the lower leaves. The changing trends of P and K content are first increasing and then decreasing, because July is the cone development period and November is the cone maturity period, and the nutritional structure changes due to different periods. Therefore, pruning can supplement or improve the nutritional structure of the tree, thereby improving the yield and quality of the seed orchard.

[0054] 3. The relationship between the ratio of N, P, K and C in the lower leaves of Chinese fir before and after pruning

[0055] The relationship between the main elements (mainly C, N, and P) required by organisms is the focus of ecological stoichiometry research. Ecostoichiometry can provide new ideas and methods for studying the balance of nutrient supply in ecosystems and the balance of elemental composition in plants. The relationship between the ratios of N, P, K, and C in the lower leaves of the Chinese fir clones before and after pruning is shown in Tables 3 and Figures 6 to 9 shown.

[0056] Table 3 Relationship between the proportions of N, P, K and C in the lower leaves of Chinese fir before and after pruning

[0057]

[0058]

[0059]

[0060] Table 3 shows the ratios of N, P, K, and C in the lower leaves of Chinese fir before and after pruning. As shown, the C / N ratio of clone 1 was significantly higher than that of clones 2 and 3 both before and after pruning, but there was no significant difference in C / N ratio before and after pruning. High C / N ratios inhibit vegetative growth, and clone 1 was the shortest, consistent with this conclusion. There were no significant differences in C / P ratios among the three clones before pruning, but in November of the year after pruning, significant differences in C / P and N / P were found between clones 2 and 3. There were no significant differences in N / P ratios among the three Chinese fir clones before and after pruning, and no significant differences in C / K ratios among the three Chinese fir clones before pruning. However, significant differences in C / K ratios were found between clone 2 and 1 in July and November after pruning. This suggests that clones with low fruit yield after pruning utilize K more efficiently than clones with moderate fruit yield.

[0061] Figure 6 It is the box plot of the ratio of N / C at different measurement times of the present invention; Figure 7 It is the box plot of the ratio of P / C at different measuring times of the present invention; Figure 8 It is the box plot of the ratio of K / C at different measurement times of the present invention;

[0062] Figure 9 The present invention presents a boxplot of the N / P ratios measured at different times. The figure shows that the C / N, C / P, C / K, and N / P ratios in July after pruning are all higher than those in July before pruning, with the C / K ratio reaching a significant level, indicating that pruning can improve the absorption of various nutrient elements in Chinese fir leaves. Meanwhile, the C / P, C / K, and N / P ratios continue to increase in November after pruning, while the C / N ratio shows a downward trend. This is because the cones mature in November, and the low C / N ratio creates favorable conditions for nutrient growth in the next year.

[0063] 4. Comparison of N, P, K and C of different whorls of lower branches after pruning

[0064] The results are shown in Tables 4 and 5 below.

[0065] Table 4 Contents of N, P, K and C in different whorls of lower branches after pruning

[0066]

[0067]

[0068] Table 4 shows the N, P, K, and C contents of different whorls of lower branches after pruning. As can be seen from the table, there was no significant difference in the N, P, K, and C contents of different whorls of lower branches in July and November after pruning, indicating that the nutrient distribution in the lower fruiting layer was relatively balanced. The N, P, and K contents in July and November after pruning showed the same trend among different whorls of branches. Among them, the N content was highest in whorls of 4-6 branches and lowest in whorls of 1-3 branches; the P content increased with the increase of whorl number; and K, contrary to P, decreased with the increase of whorl number. The C content was relatively stable, and no obvious change pattern was found. The P element plays an important role in flowering and fruiting. The fruiting layer of Chinese fir is concentrated in the middle and upper parts. Therefore, the higher the fruiting layer of Chinese fir, the higher the P content.

[0069] Table 5 The relationship between the proportions of N, P, K and C in different whorls of lower branches after pruning

[0070]

[0071] Table 5 shows the relationship between the ratios of N, P, K, and C at different whorl numbers in the lower part after pruning. As can be seen from the table, there were no significant differences in C / N, C / K, and N / P at different whorl numbers in the lower part in July and November after pruning. However, there were significant differences in C / P between whorls 1-3 and 7-9 in July after pruning. The trends of C / K and N / P at different whorl numbers in July and November after pruning were consistent. C / K increased with increasing whorl number, while N / P decreased with increasing whorl number. C / N increased with increasing whorl number in July after pruning, while C / P decreased with increasing whorl number. This indicates that changes in various nutrient elements in the leaves of Chinese fir differ during the growth period after pruning.

[0072] 5. Changes in chlorophyll content in the lower layer of Chinese fir before and after pruning

[0073] The results are as follows Figure 10 shown.

[0074] Figure 10The figure shows the change in chlorophyll content in the lower part of the tree after pruning. Different lowercase letters indicate significant differences at the 0.05 level between different clones during the same period. The figure shows that significant differences in chlorophyll content were observed between the three Chinese fir species before and after pruning. Chlorophyll content in species with medium or high fruit yields was higher than in species with low fruit yields. The trend of chlorophyll content before and after pruning for all three Chinese fir species and the control was a decrease followed by an increase, indicating that chlorophyll is primarily affected by environmental factors, with pruning having a minor impact. There was no significant difference in chlorophyll content between the pruning group No. 1 and the control before and after pruning. There was no significant difference in chlorophyll content between the pruning group No. 3 and the control before pruning, but a significant difference in chlorophyll content was observed in November of the following year after pruning, with the pruning group having a higher chlorophyll content than the control. There was a significant difference in chlorophyll content between the pruning group No. 2 and the control before pruning, with the pruning group having a higher chlorophyll content than the control. However, in November of the following year after pruning, the control group had a significantly higher chlorophyll content than the pruning group. This shows that pruning improves the photosynthetic capacity of the lower leaves of No. 3, but is not conducive to the photosynthesis of the lower leaves of No. 2, which is also one of the reasons why the lower part of No. 2 basically does not bear fruit.

[0075] 6. The content and ratio of N, P, K and C in reproductive branches and vegetative branches

[0076] The differences in the contents of N, P, K, and C in the upper reproductive and vegetative branches of three clones with different fruiting types were analyzed. The results are shown in Tables 6 and 7.

[0077] Table 6 N, P, K and C contents of reproductive branches and nutrient branches

[0078]

[0079]

[0080] Table 6 shows the N, P, K, and C contents of reproductive and vegetative branches. As can be seen, K content in reproductive and vegetative branches differed significantly across all three types, with vegetative branches having a higher K content than reproductive branches. This is because K plays a crucial role during cone development, gradually transferring from vegetative branches to reproductive branches until cones mature. P content, on the other hand, differed significantly only in the case of low fruit yield. Significant differences were observed in N, P, and K content across reproductive branches, as well as in N and K content across vegetative branches.

[0081] N content in all three types of reproductive branches was higher than in the control, while N content in vegetative branches was lower. This is because the number of cones in the upper part of the tree increases significantly after pruning, requiring sufficient N to be transferred from the vegetative branches for cone development. P content in both reproductive and vegetative branches was higher than in the control for all three Chinese fir species, indicating that pruning enhances leaf P absorption. C content in all three reproductive and vegetative branches was lower than in the control, indicating that pruning significantly reduces leaf area, weakens the plant's total photosynthetic capacity, and consequently reduces C content.

[0082] Table 7 Ratio of N, P, K and C between reproductive branches and vegetative branches

[0083]

[0084]

[0085] Table 7 shows the ratios of N, P, K, and C between reproductive branches and vegetative branches. As shown in the table, there was no significant difference in C / N between reproductive branches and vegetative branches, but there were significant differences in C / P, C / K, and N / P. After multiple comparisons, significant differences in C / P and N / P between reproductive branches and vegetative branches were found in the No. 3 pruning group, while significant differences in C / K between reproductive branches and vegetative branches were found in both No. 2 and No. 3 pruning groups.

[0086] 7. Chlorophyll content of reproductive branches and nutrient branches

[0087] The results are as follows Figure 11 shown.

[0088] Figure 11 The chlorophyll content of reproductive branches and nutrient branches is shown in the figure. The chlorophyll content of the three types of pruning groups and the control group is higher in the reproductive branches than in the nutrient branches, indicating that the photosynthetic capacity of the reproductive branches is higher than that of the nutrient branches. There was no significant difference in the chlorophyll content of the reproductive branches and nutrient branches between the three pruning groups and the control group. The chlorophyll content of reproductive branch No. 1 was higher than that of the control, while the chlorophyll content of reproductive branches No. 2 and No. 3 was lower than that of the control; the chlorophyll content of nutrient branches No. 1 and No. 2 was lower than that of the control, while the chlorophyll content of nutrient branches No. 3 was higher than that of the control. After multiple comparisons, it was found that there were significant differences in the chlorophyll content of reproductive branches and nutrient branches No. 1 and No. 3. Because the No. 3 tree is taller and has a larger crown, it has a larger leaf area and a stronger photosynthetic capacity.

[0089] 8. The results of the correlation analysis between the content and ratio of N, P, K and C in Chinese fir leaves and the germination rate and number of cones are as follows: Figures 12-15 shown.

[0090] Figure 12 This is a heat map of correlation coefficients of nutrient elements in upper reproductive branches the year after pruning. Samples were taken in July 2022. The figure shows that N, P, and K in reproductive branches are negatively correlated with germination rate, while C, C / N, C / P, C / K, and N / P are positively correlated with germination rate, but none of these correlations are significant. N in reproductive branches has a significant positive correlation with C content, but a highly significant negative correlation with C / N.

[0091] Figure 13This is a heat map of correlation coefficients of nutrient elements in upper vegetative branches the year after pruning, sampled in July 2022. The figure shows that N, P, and K in vegetative branches are negatively correlated with germination rate, while C, C / N, C / P, C / K, and N / P are positively correlated with germination rate. Germination rate is significantly correlated with C content, but the correlations with other indicators are not significant. In summary, the correlations between nutrient elements and germination rate in reproductive and vegetative branches are generally consistent, with N, P, and K all showing negative correlations with germination rate.

[0092] Figure 14 This is a heat map of correlation coefficients of nutrients in the lower nutrient branches before pruning. The figure shows that the germination rate of the lower nutrient branches before pruning was negatively correlated with N, P, K, C, and C / K, and positively correlated with C / N, C / P, and N / P, but none of the correlations were significant. The number of cones was negatively correlated with N, P, K, C, and C / K, and positively correlated with C / N, C / P, and N / P. The number of cones was significantly negatively correlated with N content, but the correlations with other indicators were not significant.

[0093] Figure 15 This is a heat map of correlation coefficients of nutrient elements in the lower nutrient branches after pruning. The figure shows that the germination rate of the lower nutrient branches after pruning is negatively correlated with N, K, C, C / P, and N / P, and positively correlated with P, C / N, and C / K. Germination rate has a significant negative correlation with N, but no significant correlations with other indicators. This indicates that the germination rate and cone number of Chinese fir are closely related to N.

[0094] In summary, the N and P contents of leaves of high-yield mother trees were higher than those of low-yield mother trees, while the K content was higher in low-yield mother trees than in high-yield mother trees, but the differences in the content of each element did not reach a significant level. However, the N, P, and K contents of leaves of the high-yield mother trees in the present invention were all higher than those of the low-yield mother trees, and the difference in N content reached an extremely significant level. The N content of the low-yield mother trees in the present invention was 10.97 g·kg -1 , P content is 1.58g·kg -1 , K content is 8.81 g·kg -1 The N content of the medium-sized fruit is 15.36 g·kg -1 , P content is 1.73 g·kg -1 , K content is 10.64 g·kg -1 The N content of the largest amount of fruit is 14.16 g·kg -1 , P content is 1.82 g·kg -1 The K content of the Chinese fir clones of the present invention was within the optimum concentration range, while the P content was lower than the optimum concentration range, which was related to the lack of P in the soil of the test site.

[0095] The N and C contents of the present invention showed significant differences before and after pruning, while the P and K contents did not change significantly. This is because pruning has little effect on the plant's ability to absorb and utilize phosphorus and potassium, while the phosphorus and potassium content in plant leaves is mainly affected by factors such as the soil phosphorus and potassium content and the plant's own phosphorus and potassium absorption capacity.

[0096] The nitrogen element is closely related to the growth status of forest trees and is an important component of plant chloroplasts. The higher the nitrogen content, the higher the chlorophyll content and the improved photosynthesis. The variation trend of the nitrogen content in the present invention is consistent with that of the chlorophyll content. The nitrogen content and chlorophyll content of No. 2 and No. 3 are higher than those of No. 1 before and after pruning. Moreover, the growth of tree height, diameter at breast height and crown width of No. 2 and No. 3 after pruning is significantly greater than that of No. 1, indicating that the plants with less fruit yield have low nitrogen content, low chlorophyll content and short plants; while the plants with medium and large fruit yield have high nitrogen content, high chlorophyll content and tall plants. Correlation analysis shows that after pruning of Chinese fir, the nitrogen content is closely related to the seed germination rate and the number of cones. The nitrogen content is significantly different before and after pruning, and the nitrogen content is significantly increased after pruning, indicating that pruning is beneficial to the absorption of nitrogen content in plants.

[0097] The element P promotes root growth and plays an important role in flowering and fruiting. The element P is beneficial to increasing crop yields. A large amount of phosphorus is transferred to the cones, making the cones of red pine plump. Before pruning, the P content was lowest in the case of small fruit bearing, and the P content was highest in the case of large fruit bearing; after pruning, the P content differed significantly between the cases with medium fruit bearing and those with large fruit bearing. The P content was lowest in the case of medium fruit bearing, and the P content was highest in the case of large fruit bearing. The P content of the cases with small fruit bearing was significantly higher than before pruning, which resulted in the cases with medium fruit bearing almost no fruit bearing, the cases with large fruit bearing the most fruit, and the fruiting of the cases with small fruit bearing increased.

[0098] The K element is primarily involved in plant metabolism and is closely related to plant photosynthesis. Increased K content significantly improves N absorption and utilization efficiency. Therefore, plant K content is similar to N content and higher than P content, which is consistent with the conclusions of the present invention. The K content and N content change trends are consistent before and after pruning. K transports proteins produced by photosynthesis to cones and seeds, and a K deficiency results in low seed 1000-grain weight. No. 1 of the present invention has the lowest K content and the lowest 1000-grain weight.

[0099] The content of C in the plant body is relatively high and stable. The difference in C content before and after pruning in this invention is significant, and the C content increases significantly after pruning. Element C is often used to study the proportional relationship of C, N, and P in leaves. C / N and C / P can reflect the accumulation and storage ability of C during plant growth and the utilization efficiency of N and P by plants. The C / N and C / P of leaves are relatively high in July. Compared with July after pruning, the C / N of No. 1 increases before pruning in July, while the C / N of No. 2 and No. 3 decreases, indicating that the utilization efficiency of N element increases after pruning for those with less fruit set, while the utilization efficiency of N element decreases after pruning for those with medium and high fruit set. After pruning, the C / N of those with less fruit set increases, and the seed and cone yield and quality are improved.

[0100] Using N / P to judge the limiting nutrient factor for tree growth During the growth process of plants, N / P < 14 indicates that the growth of plants is more strongly restricted by N element, N / P > 16 indicates that the growth of plants is more strongly restricted by P element, and 14 < N / P < 16 indicates that the growth of plants is jointly restricted by N and P. Before pruning in this invention, N / P was all less than 14, indicating that the growth of Chinese fir plants was strongly restricted by N deficiency. In November after pruning, the N / P of No. 2 was between 14 and 16, indicating that No. 2 after pruning was jointly restricted by N and P. Therefore, the cone yield and quality of No. 2, that is, those with medium fruit set, decreased.

[0101] There are differences in the mineral nutrient element content of leaves between vegetative branches and reproductive branches, but it varies depending on the type of nutrient element and the growth and development period of the plant. This invention found that there is a significant difference in K content between reproductive branches and vegetative branches. The chlorophyll content of reproductive branches is significantly higher than that of vegetative branches.

[0102] After pruning, the correlation between the nutrient elements of the upper reproductive branches and vegetative branches and the seed germination rate is basically the same. The germination rate is negatively correlated with N, P, and K elements, but not significantly. There is a significant negative correlation between the N element of the lower vegetative branches and the germination rate and the number of cones. This is because the plant has a large amount of flowers and a high fruit set rate, and the construction of organs in the early stage consumes the nutrients stored in the previous year. Therefore, the accumulation of nutrient elements such as N, P, and K in the leaves decreases rapidly.

Claims

1. A method for regulating nutrient elements in Chinese fir leaves, characterized in that: The fir trees were pruned in the middle, with branches retained at the upper and lower parts. The row spacing of the fir trees was 3m×3m. The nutrient elements were N, P and K. Nine rounds of branches were retained at the upper part and three rounds of branches were retained at the lower part. The fir trees with a fruit yield of 250 to 1000 cones per plant were selected.

2. The method for regulating nutrient elements in Chinese fir leaves according to claim 1, wherein: The concentration of nitrogen in fir needles is 10~16g / kg.

3. The method for regulating nutrient elements in Chinese fir leaves according to claim 2, characterized in that: The concentration of P in fir needles is 1~2g / kg.

4. The method for regulating nutrient elements in Chinese fir leaves according to claim 2, wherein: The concentration of K in fir needles is 8~11g / kg.

5. The method for regulating nutrient elements in Chinese fir leaves according to claim 1, characterized in that: The north-south crown width of Chinese fir is larger than the east-west crown width.

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