Method for analyzing quality influence factors of upper six tobacco leaves

Abstract

The invention belongs to the technical field of tobacco cultivation, and particularly relates to a method for analyzing quality influence factors of upper six tobacco leaves, which comprises the following steps of: setting treatment groups with different biochar dosages, different transplanting periods, different nitrogen application amounts, topping periods, leaf remaining numbers and different fertilization modes, and respectively carrying out tobacco planting tests; measuring agronomic characters of the tobacco plants at different time points after the tobacco leaves are transplanted; collecting a soil sample near a tobacco plant root system in a tobacco vigorous growth period, and analyzing the diversity of soil microbial communities; measuring the appearance quality, physical properties, chemical components and fragrant substances of the tobacco leaves; and performing sensory quality evaluation on the tobacco leaf sample by a sensory evaluation expert group in the tobacco industry, and finally determining the quality influence of different treatments on the upper six tobacco leaves according to determination and analysis results. According to the method, the influence of factors such as the biochar dosage, the transplanting period, the nitrogen application amount, the topping period, the leaf remaining number and the fertilization mode on the quality of the upper six tobacco leaves is systematically researched, and the tobacco leaf quality is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco leaf cultivation, and particularly relates to a method for analyzing factors affecting the quality of six tobacco leaves. Background Art

[0002] Xuchang's "Shangliupian" tobacco, a hallmark of Henan's high-quality tobacco, features a loose structure, harmonious chemical composition, a full and rich aroma, good aroma quality, ample aroma volume, high concentration, a pleasant aftertaste, and a strong formula. In recent years, "Shangliupian" tobacco from the Xuchang tobacco region has become a crucial raw material for Henan China Tobacco's "Golden Leaf" brand and "Tian Series" cigarettes, playing a crucial role in the development of high-end cigarette brands. Over the past decade, tobacco researchers have conducted detailed research on Xuchang "Shangliupian" tobacco varieties, including cultivar selection, soil conservation and cultivation optimization, pest and disease control, harvest maturity control, and curing process development. For example, Shi Hongzhi et al. conducted a series of studies on the cultivation practices of "Shangliupian" tobacco in central Henan, focusing on transplanting and harvesting periods, leaf length, nitrogen application rates, planting density, number of leaves left, and accumulated temperature during maturity. These studies provide reliable technical support for the production of high-quality "Shangliupian" tobacco.

[0003] However, the production of "Upper Six Pieces" tobacco leaves in the Xuchang tobacco region still faces problems such as a low overall yield of high-quality tobacco leaves, large differences in the quality of tobacco leaves produced at different tobacco stations, and large inter-annual fluctuations in the quality of "Upper Six Pieces" tobacco leaves at some stations. Therefore, it is urgent to conduct systematic research on the nutritional regulation of tobacco plants, the optimization of cultivation techniques, and the control of tobacco leaf harvest maturity, based on the product requirements of the "Golden Leaf" cigarette brand and the "Tian Series" cigarette products, and guided by quality influencing factors, in order to further improve the quality compliance of "Upper Six Pieces" tobacco leaves. Summary of the Invention

[0004] In view of this, the present invention proposes a method for analyzing factors affecting the quality of six tobacco leaves to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions:

[0006] A method for analyzing factors affecting the quality of six tobacco leaves, comprising the following steps:

[0007] Tobacco planting experiments were conducted in different treatment groups with different biochar dosages, transplanting periods, nitrogen application rates, topping periods, number of leaves left, and fertilization methods.

[0008] At different time points after transplanting tobacco leaves, the agronomic traits of tobacco plants were measured;

[0009] Soil samples were collected near the roots of tobacco plants during the tobacco's peak growth period to analyze the diversity of soil microbial communities;

[0010] Determine the appearance quality, physical properties, chemical composition and aroma substances of tobacco leaves;

[0011] A sensory evaluation expert group from the tobacco industry will conduct sensory quality evaluation on tobacco leaf samples;

[0012] Based on the agronomic trait measurement results, the soil microbial community diversity, the appearance quality, physical properties, chemical composition and aroma substance measurement results and the sensory quality evaluation results, the effects of biochar dosage, transplanting period, nitrogen application amount, topping period and number of leaves left, and fertilization method on the quality of the top six tobacco leaves were determined respectively.

[0013] Furthermore, the soil microbial community diversity analysis includes the determination of Chao1, Shannon, Observed_species, Goods_coverage and OTUs indicators.

[0014] Furthermore, the agronomic traits include plant height, stem girth, maximum leaf length, leaf width and leaf area.

[0015] Furthermore, the appearance quality evaluation index includes color, maturity, leaf structure, identity, oil content and chroma;

[0016] The physical properties measurement indicators include leaf length, leaf width, stem content, leaf weight, single leaf weight, tensile strength, thickness, filling value and equilibrium moisture content;

[0017] The chemical composition determination indicators include total sugar, reducing sugar, nicotine, potassium, chlorine, and total nitrogen, and the sugar-alkali ratio, nitrogen-alkali ratio, and potassium-chlorine ratio are calculated;

[0018] The determination of the aroma substances is carried out by gas chromatography-mass spectrometry to detect the types and contents of the aroma substances in the tobacco leaves.

[0019] Furthermore, the sensory quality evaluation indicators include aroma quality, aroma quantity, permeability, concentration, softness, aftertaste, miscellaneous smell, irritation, flammability and grayness.

[0020] Furthermore, the results of tobacco planting experiments with different biochar dosages showed that the top six tobacco leaves obtained by applying 1.0 t / mu of biochar had the best quality.

[0021] Furthermore, the results of tobacco planting experiments with different nitrogen application rates, topping periods and number of leaves left showed that the combination of nitrogen application rate of 2 kg / mu, topping at full flowering and 22 leaves left achieved the best tobacco quality.

[0022] Furthermore, the results of tobacco planting experiments conducted by setting different fertilization methods showed that the quality of the top six tobacco leaves obtained by the integrated water and fertilizer drip irrigation method was the best.

[0023] Furthermore, the integrated water and fertilizer drip irrigation fertilization method includes: base fertilizer using 10 kg / mu of compound fertilizer; topdressing with 10 kg / mu of compound fertilizer, 8.4 kg / mu of superphosphate, and 7.69 kg / mu of water-soluble potassium sulfate; 5 days before topping, water-soluble potassium sulfate fertilizer N:P2O5:K2O=0:0:52 is used, and the amount of potassium fertilizer is supplemented through integrated water and fertilizer, 3.84 kg / mu each time.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention significantly improves tobacco leaf quality by systematically studying the effects of factors such as biochar dosage, transplanting period, nitrogen application rate, topping period, number of leaves left, and fertilization method on the quality of the upper six tobacco leaves. The present invention draws the following conclusions:

[0026] Biochar application: The application of 1.0 t / mu of biochar can significantly improve the agronomic traits of tobacco plants, increase soil microbial diversity, optimize the appearance quality, physical properties, chemical composition and aroma substances of tobacco leaves, and significantly improve the sensory quality.

[0027] Transplanting period optimization: Tobacco leaves transplanted on April 23 performed best in terms of appearance quality, chemical composition, aroma substances and sensory quality, and were significantly better than other transplanting period treatments.

[0028] Nitrogen application rate and cultivation measures: The combination of nitrogen application rate of 2 kg / mu, topping at full flowering and leaving 22 leaves performed best in terms of tobacco leaf appearance, physical properties, chemical composition and sensory quality.

[0029] Improvement in fertilization methods: The integrated water-fertilizer drip irrigation method has significantly improved the appearance quality, physical properties, chemical composition and types of aromatic substances in tobacco leaves, and improved the sensory quality of tobacco leaves.

[0030] In summary, the present invention provides a scientific basis for the production of high-quality tobacco leaves by precisely controlling various factors, and significantly improves the overall quality of the upper six tobacco leaves. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the overall process of the method of the present invention;

[0032] Figure 2A and Figure 2B Comparison of agronomic shapes of flue-cured tobacco at different stages treated with different biochar application rates in the embodiment of the present invention, where ( Figure 2A ) is the comparison of plant height and stem girth; ( Figure 2B) is the comparison of maximum leaf area;

[0033] Figure 3 This is a Venn diagram of the OTUs distribution of soil samples treated with different nitrogen application rates in an embodiment of the present invention;

[0034] Figure 4A and Figure 4B is a bar graph of relative species abundance of soil samples treated with different biochar application rates in the embodiment of the present invention, where ( Figure 4A ) is the relative abundance column of bacteria at the phylum level, ( Figure 4B ) is the relative abundance column of bacteria at the genus level;

[0035] Figure 5 The PCA principal component analysis results of different biochar application amounts in the examples of the present invention are shown. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] This embodiment proposes a method for analyzing factors affecting the quality of six tobacco leaves, such as Figure 1 Shown, including:

[0038] This experiment was conducted in Jiangzhuang Township. The test variety was Zhongyan 100, with a row spacing of 1.3 m x 0.60 m. A randomized block design was used. Base fertilizer was 15 kg / mu of compound fertilizer (N:P2O5:K2O = 15:15:15), 10 kg / mu of Lop Nur potash fertilizer (N:P2O5:K2O = 0:0:50), and topdressing was 25 kg / mu of Lop Nur potash fertilizer applied in holes. Transplanting took place on May 19th, and field management was carried out in accordance with local cultivation standards. Four treatments were set up, each with three replicates, based on different biochar dosages. Each plot area was 0.162 mu. The treatments are shown in Table 1:

[0039] Table 1

[0040]

[0041] (1) Agronomic trait measurement methods:

[0042] According to the Survey and Measurement Methods for Agronomic Traits of Tobacco (YC / T 142-2010), 5 representative tobacco plants were selected in each plot 30, 60, and 90 days after tobacco transplanting. Agronomic traits such as plant height, stem girth, maximum leaf length, and leaf width were measured, and leaf area was calculated (leaf area = leaf length × leaf width × 0.6345).

[0043] (2) Rhizosphere soil sampling method:

[0044] During tobacco's vigorous growth period (60 days after transplanting), soil samples were collected from the 0-20 cm depth near the tobacco plant roots using a five-point sampling method. Debris, such as stones and plant roots, was removed from the soil samples, mixed thoroughly, passed through a 2 mm sieve, and stored in a refrigerator at 4°C. Microbial community diversity profiles were analyzed for the collected soil samples.

[0045] (3) The determination of tobacco leaf appearance quality, physical properties, chemical composition and aroma substances shall be carried out in accordance with standard methods.

[0046] (4) Evaluation method of tobacco leaf sensory quality:

[0047] A panel of seven tobacco industry sensory evaluation experts conducted a sensory quality evaluation of tobacco leaf samples. Evaluation criteria included aroma, pungency, and concentration. The evaluation method used the tobacco industry's single-leaf sensory quality evaluation method, assigning each quality indicator a 9-point scale. The overall score is (aroma × 0.3 + aroma volume × 0.3 + miscellaneous flavors × 0.08 + pungency × 0.15 + aftertaste × 0.17) × 11.1.

[0048] Results and Analysis:

[0049] Effects of different biochar application rates on agronomic traits of tobacco leaves:

[0050] To analyze the effects of different biochar treatments on the growth and development characteristics of the upper six leaves, this experiment measured the agronomic traits of tobacco plants treated with CK, D1, D2, and D3 at 60 and 90 days after transplantation. Figure 2A )、Maximum leaf area( Figure 2B ) and other indicators. The results showed that biochar treatment had no significant effect on tobacco plant growth and development 60 days after transplanting. At 90 days after transplanting, plant height, stem girth, and maximum leaf area showed a trend of D3 > D2 > D1 > CK. The experimental results indicate that biochar has a certain effect on tobacco plant growth and development, with the D2 treatment being the most effective. Under this treatment, plant height, stem girth, and maximum leaf area best matched the growth characteristics of high-quality upper six-leaf tobacco.

[0051] The statistical effects of different biochar application rates on tobacco rhizosphere microorganisms are shown in Table 2:

[0052] (1) Diversity analysis:

[0053] Table 2

[0054]

[0055] Comprehensive analysis of the relevant data in Table 2 shows that compared with CK, the Chao1, observed_species and Shannon values ​​of D1 treatment increased by 12.64%, 13.05% and 1.90%, respectively; the Chao1, observed_species and Shannon values ​​of D2 treatment were higher than those of CK, with increases of 8.48%, 8.51% and 0.07%, respectively; the Chao1, observed_species and Shannon values ​​of D3 treatment were higher than those of CK, at 12.83%, 13.71% and 1.64%, respectively; the number of OTUs in D1, D2 and D3 treatments increased significantly compared with CK, with increases of 5.80%, 9.53% and 6.66%, respectively. The experimental results show that after the application of biochar, the bacterial microorganisms and diversity in tobacco-growing soil showed a significant increasing trend.

[0056] (2) Bacterial OTUs distribution:

[0057] Depend on Figure 3 The total number of bacterial OTUs in soil samples from each treatment was 29,860, of which 2,833 were shared across the four treatments. The numbers of unique OTUs in soil samples from the CK, D1, D2, and D3 treatments were 4,533, 5,859, 5,145, and 4,878, respectively. Compared with the CK treatment, the number of unique OTUs in D1 was 7,282, accounting for 24.39% of the total OTUs; the number of unique OTUs in D2 was 7,086, accounting for 23.74% of the total OTUs; and the number of unique OTUs in D3 was 8,149, accounting for 27.29% of the total OTUs. The number of OTUs shared by D1, D2, and D3 was 707, indicating that the soils treated with biochar had more similar microbial compositions. Biochar application significantly increased the number of bacterial OTUs in the soil, and the greater the amount of biochar applied, the greater the effect on the number of bacterial OTUs.

[0058] (3) Bacterial community species composition and relative abundance:

[0059] By counting the specific composition of the microbial community at each taxonomic level in each sample, the data in the table above were plotted into a bar chart using an R script to visually display the number of taxonomic units at each taxonomic level in different samples. Figure 4AIt can be seen that the main bacterial groups at the phylum level in the soils of the four treatments are Actinobacteria, Alphaproteobacteria, Gammaproteobacteria, Thermooleobacteria, Proteobacteria, Gemmatimonadetes, and Acidobacteria-6. Figure 4B It can be seen that the main bacterial groups at the genus level in the four treatment soils are Monosporus, Pseudomonas, Streptomyces, Nocardia, Aeromicrobium, and Sporomonas.

[0060] Bacterial community species composition and relative abundance:

[0061] PCA principal component analysis results ( Figure 5 ) shows that principal component 1 (PC1) and principal component 2 (PC2) explain 29% and 18.7% of the variance among treatment samples, respectively, for a total of 47.7%. CK and D2 sample points are primarily distributed in the negative semi-axis region of PC1, while D3 and D1 are primarily concentrated in the positive semi-axis region of PC1. However, these two points are slightly symmetrical and dissimilar relative to the PC2 axis. The relative positions of the sample points in the figure show that D1 and D2 have more similar bacterial species composition and are further away from CK than D3, further indicating that biochar application altered the species composition and distribution of soil bacteria.

[0062] The statistical effects of different biochar application rates on the appearance quality of the top six tobacco leaves are shown in Table 3:

[0063] Table 3

[0064]

[0065] Table 3 shows that compared to the control, the appearance quality of the top six tobacco leaves treated with biochar was significantly improved. Furthermore, with increasing biochar application, the color, maturity, leaf structure, texture, oil content, and chroma of the top six leaves all showed an initial increase followed by a decrease. All leaf indicators were optimal when biochar application was at D2. Overall, applying an appropriate amount of biochar can effectively improve tobacco leaf appearance quality, as evidenced by an orange-yellow color, good maturity, moderate leaf thickness, high oil content, and strong chroma in the top six leaves after curing. The appearance quality of tobacco leaves treated with D2 was the best. Adding 1.0 t / mu of biochar to normal basal fertilizer application significantly improved tobacco leaf appearance quality.

[0066] The statistical effects of different biochar application rates on the physical properties of the top six tobacco leaves are shown in Table 4:

[0067] Table 4

[0068]

[0069] As shown in Table 4, with increasing biochar application, leaf weight, thickness, and equilibrium moisture content all showed a trend of first increasing and then decreasing. Treatment D2 had the highest leaf weight, thickness, and equilibrium moisture content, significantly higher than the control group. The stem content gradually decreased with increasing biochar application. With the exception of treatment D2, the stem content of the other two treatments was lower than that of the control group, with treatment D3 having the lowest stem content. With increasing biochar application, the filling value and tensile strength decreased, but the filling value of treatment D2 was not much different from that of the control group, and the tensile strength of treatment D2 was slightly higher than that of the control group. Other physical properties, such as leaf length, leaf width, and single leaf weight, did not change significantly. Overall, applying an appropriate amount of biochar can effectively improve the physical properties of tobacco leaves, increasing leaf weight, thickness, and equilibrium moisture content, and reducing the stem content. Treatment D2 exhibited the best physical properties. Applying 1.0 t / mu of biochar in addition to normal basal fertilizer application significantly improved the physical properties of tobacco leaves.

[0070] The statistical effects of different biochar application rates on the chemical composition of the top six tobacco leaves are shown in Table 5:

[0071] Table 5

[0072]

[0073] Table 5 shows that with increasing biochar application, total sugars, reducing sugars, and the potassium-to-chloride ratio all increased significantly within a certain range. Treatment D2 had the highest total sugar content, significantly higher than treatments D1 and D3. Treatments D2 and D3 also had significantly higher reducing sugar contents than treatment D1 and the control, but the differences between the two were not significant. Treatments D1, D2, and D3 all had higher potassium-to-chloride ratios than the control, with treatment D3 having significantly higher potassium-to-chloride ratios than treatments D1 and D2. Treatments D1, D2, and D3 all had lower chlorine contents than the control, indicating that biochar application effectively reduced the chlorine content of tobacco leaves. The chlorine content of treatment D3 was significantly lower than that of treatments D1 and D2. Changes in the contents of other chemical components fluctuated less significantly. Overall, applying an appropriate amount of biochar significantly increased total sugars, reducing sugars, and the potassium-to-chloride ratio in tobacco leaves, and reduced their chlorine content. Treatment D2 exhibited the best chemical composition. Applying 1.0 t / mu of biochar in addition to normal basal fertilizer application significantly improved the chemical composition and balance of tobacco leaves.

[0074] The statistical effects of different biochar application rates on the aroma substances in the top six tobacco leaves are shown in Table 6:

[0075] Table 6

[0076]

[0077] Table 6

[0078]

[0079] As shown in Table 6, 15 aroma compounds were detected in the control group, 21 in the D1 treatment, 22 in the D2 treatment, and 17 in the D3 treatment. With increasing biochar application, the number of aroma compounds initially increased and then decreased. The D2 treatment had the highest number of aroma compounds, significantly higher than the control group. Compared to the control group, the biochar-treated tobacco leaves showed an increase in the number of aroma compounds, including 1-penten-3-one, trans-2-pentenal, and phenylethyl acetate. These compounds have ethereal, peppery, spicy, rose, floral with a honey-like undertone, and sweet strawberry aromas, respectively, enhancing the spicy, floral, and fruity aromas of the tobacco leaves. In general, the types of aromatic substances in tobacco leaves treated with biochar increased, and the aroma of the aromatic substances was enriched, which could improve the aroma quality and quantity of tobacco leaves, making the aroma of tobacco leaves fuller. The D2 treatment was the best. Applying 1.0 t / mu of biochar on the basis of normal application of base fertilizer could significantly increase the types of aromatic substances in tobacco leaves.

[0080] The statistical effects of different biochar application rates on the sensory quality of the top six tobacco leaves are shown in Table 7:

[0081] Table 7

[0082]

[0083] As shown in Table 7, the application of biochar can improve the sensory quality of tobacco leaves. Compared with the control group, the sensory quality of treatments D1, D2, and D3 all improved. The aroma quality and permeability of the D1 treatment were both improved. The aroma quality, aroma volume, and permeability of the D2 treatment were all improved, and the impurities were reduced. The aroma quality and permeability of the D3 treatment were also improved, with little difference from the D1 treatment, but lower than the D2 treatment. Overall, the application of biochar can significantly improve the sensory quality of tobacco leaves, especially the aroma quality and permeability, which were generally improved. The D2 treatment was the best. Applying 1.0 t / mu of biochar on the basis of normal basal fertilizer application can improve the sensory quality of tobacco leaves.

[0084] Summarize:

[0085] Applying different amounts of biochar effectively improved tobacco leaf quality. Biochar application significantly improved plant height, stem girth, and leaf area, significantly enhancing leaf appearance, physical properties, chemical composition, aroma compounds, and sensory evaluation. Various tobacco leaf quality evaluation indicators varied significantly among the different treatments, but treatment D2 was found to be optimal. In summary, in the biochar soil improvement experiment in Jiangzhuang, applying 1.0 t / mu of biochar achieved the best soil improvement results.

[0086] Effects of different transplanting periods on the quality of upper six tobacco leaves:

[0087] This example adopts randomized block design, with base fertilizer of 15kg / mu of compound fertilizer, 10kg / mu of Lop Nur potash fertilizer, and topdressing of 25kg / mu of Lop Nur potash fertilizer. Three treatments were set according to different transplanting dates, each with three replicates. The area of ​​each plot was 0.061 mu. The treatment results are shown in Table 8:

[0088] Table 8

[0089]

[0090] Measurement items and methods:

[0091] (1) Agronomic trait measurement methods:

[0092] According to the Survey and Measurement Methods for Agronomic Traits of Tobacco (YC / T 142-2010), 5 representative tobacco plants were selected in each plot 30, 60, and 90 days after transplanting. Agronomic traits such as plant height, stem girth, internode length, leaf number, and maximum leaf length and width were measured, and leaf area was calculated (leaf area = leaf length × leaf width × 0.6345).

[0093] (2) Determination of tobacco leaf appearance quality, physical properties, chemical composition, and aroma substances:

[0094] The appearance quality, physical properties, chemical composition and aroma substances are all the same as those used in the above examples.

[0095] (3) Evaluation method of tobacco leaf sensory quality:

[0096] A panel of seven tobacco industry sensory evaluation experts conducted a sensory quality evaluation of tobacco leaf samples. Evaluation criteria included aroma, pungency, and concentration. The evaluation method used the tobacco industry's single-leaf sensory quality evaluation method, assigning each quality indicator a 9-point scale. The overall score is (aroma × 0.3 + aroma volume × 0.3 + miscellaneous flavors × 0.08 + pungency × 0.15 + aftertaste × 0.17) × 11.1.

[0097] Results and Analysis:

[0098] Effects of different transplanting periods on agronomic traits of tobacco leaves:

[0099] To clarify the effects of different transplanting dates on tobacco plant agronomic traits, agronomic traits of tobacco plants treated differently were monitored at different stages of their growth cycle. The results showed that plant height and stem girth increased almost proportionally with delayed transplanting. Because topping was performed after 70 days, plant height and stem girth at 90 days increased to varying degrees compared to 60 days, with Y2 plants significantly higher than Y3 and Y1. Comparison of leaf area in the middle and upper leaves among treatments 90 days after transplanting revealed that the middle and upper leaves of Y2 grew better after topping, while the upper six leaves of Y3 grew faster.

[0100] The statistics of tobacco leaf appearance quality at different transplanting periods are shown in Table 9:

[0101] Table 9

[0102]

[0103] Table 9 shows that different transplanting dates significantly affected the appearance quality of the top six leaves. The Y3 treatment showed higher color, maturity, leaf structure, identity, oil content, and chroma than the Y1 and Y2 treatments. The appearance quality of the top six leaves gradually improved with delayed transplanting, with the Y3 treatment achieving the best results. The top six leaves transplanted on April 23rd had the best chemical composition.

[0104] The statistical results of the effects of different transplanting periods on the physical properties of the top six tobacco leaves are shown in Table 10:

[0105] Table 10

[0106]

[0107] Table 10 shows that different transplanting dates significantly affected the physical properties of the top six tobacco leaves. Treatment Y1 demonstrated superior physical properties such as leaf length, leaf width, stem content, tensile strength, thickness, filling value, and equilibrium moisture content compared to treatments Y2 and Y3. Treatment Y2 also demonstrated superior leaf weight to treatments Y1 and Y3. Furthermore, treatment Y2 also demonstrated superior leaf length, leaf width, stem content, tensile strength, thickness, filling value, and equilibrium moisture content compared to treatment Y3. Comprehensively analyzing all physical property indicators, treatment Y1 outperformed both treatments Y2 and Y3. Overall, treatment Y1, transplanting on April 23, had the greatest impact on the physical properties of the top six tobacco leaves.

[0108] The statistical analysis of the effects of different transplanting periods on the chemical composition of the top six tobacco leaves is shown in Table 11:

[0109] Table 11

[0110]

[0111] Table 11 shows that different transplanting dates significantly affected the chemical composition of the top six tobacco leaves. Treatment Y1 showed higher total sugar, reducing sugar, nicotine, potassium content, sugar-alkali ratio, and potassium-chloride ratio than treatments Y2 and Y3, while chlorine content and total nitrogen were lower than those in treatments Y2 and Y3. With delayed transplanting, total sugar, reducing sugar, nicotine, and sugar-alkali ratio showed a continuous downward trend, while total nitrogen showed an initial increase followed by a decrease. Chlorine content showed an initial increase followed by a decrease, with Y3 still showing a higher level than Y1. Overall, the chemical composition quality of the top six tobacco leaves deteriorated with delayed transplanting, with treatment Y1 showing the best chemical composition quality, and the top six tobacco leaves transplanted on April 23rd showed the best chemical composition quality.

[0112] The statistical analysis of the effects of different transplanting periods on the aroma substances in the top six tobacco leaves is shown in Table 12:

[0113] Table 12

[0114]

[0115] Table 12

[0116]

[0117] Table 12 shows that 23 aroma compounds were detected in the Y1 treatment, 18 in the Y2 treatment, and 16 in the Y3 treatment. With the delay of the transplanting date, the aroma compounds in the upper six leaves showed a trend of initially rapid decrease followed by a gradual decrease. The Y1 treatment had the highest variety of aroma compounds, significantly higher than those in the Y2 and Y3 treatments. Compared with the Y2 and Y3 treatments, the Y1 treatment had increased aroma compounds such as 1-penten-3-one, ethyl hexanoate, and 2-pentylfuran. These compounds have spicy, ethereal, peppery, and fruity aromas, respectively, and can enhance the spicy and fruity aromas of the tobacco leaves. Overall, the Y1 treatment had the richest variety of aroma compounds in the upper six leaves, with slightly higher content. Transplanting on April 23rd significantly increased the variety and content of aroma compounds in the upper six leaves.

[0118] The statistical analysis of the effects of different transplanting periods on the sensory quality of the top six tobacco leaves is shown in Table 13:

[0119] Table 13

[0120]

[0121] As shown in Table 13, there are significant differences in sensory quality evaluations between treatments with different transplanting periods. As the transplanting period is delayed, the sensory quality of the six tobacco leaves after curing shows a gradually declining trend. The sensory quality evaluation indicators of the Y1 treatment, such as aftertaste, irritation, burnability, and gray, are better. The sensory quality evaluation indicators of the Y2 treatment, such as aroma volume, permeability, and concentration, are all better. All indicators of the Y3 treatment are worse. There is no difference in aroma quality, fineness, and foreign matter between the Y1 and Y2 treatments, and both are better than the Y3 treatment. In summary, the Y1 treatment is better than the Y2 and Y3 treatments. Overall, the sensory quality of the Y1 treatment, i.e., the six tobacco leaves transplanted on April 23, is the best. It can effectively reduce the irritation of tobacco leaves, enhance the comfort of the aftertaste, improve burnability, and improve the gray color of ash.

[0122] The test results showed significant differences between treatments in agronomic traits, leaf appearance, physical properties, chemical composition, aroma compounds, and sensory evaluation. Treatment Y1 outperformed treatments Y2 and Y3. Treatment Y1 achieved the best results for all leaf quality evaluation indicators. In summary, the effect of different transplanting dates on the quality of the first six leaves was found to be best when transplanted on April 23rd. During production, it is recommended to transplant earlier than necessary, depending on local conditions.

[0123] Effects of different nitrogen application rates, topping periods, and number of leaves left on the quality of the upper six tobacco leaves:

[0124] The test used L9(3 4 ) Orthogonal experimental design was used to study the nitrogen application rate, topping method and the number of leaves left.

[0125] The nitrogen application rate was set at three levels: N = 2 kg / mu (A1), N = 3 kg / mu (A2) and N = 4 kg / mu (A3). Topdressing was carried out 26 days after transplanting, and Lop Nur potassium fertilizer and superphosphate (N:P2O5:K2O=0:0:12) were applied to control the consistency of phosphorus fertilizer and potassium fertilizer content.

[0126] There are three levels of topping: bud topping (B1), initial flowering topping (B2), and full flowering topping (B3).

[0127] The number of leaves left was set at three levels: 20 leaves (C1), 22 leaves (C2), and 24 leaves (C3).

[0128] L9(3 4 ) Orthogonal experimental design was used, with 9 treatments in total, 3 replicates for each treatment, and 18 plots in total.

[0129] The different experimental treatment designs are shown in Table 14:

[0130] Table 14

[0131]

[0132] Measurement items and methods:

[0133] (1) Agronomic trait measurement methods:

[0134] According to the Survey and Measurement Methods for Agronomic Traits of Tobacco (YC / T 142-2010), 5 representative tobacco plants were selected in each plot 30, 60, and 90 days after transplanting. Agronomic traits such as plant height, stem girth, internode length, leaf number, and maximum leaf length and width were measured, and leaf area was calculated (leaf area = leaf length × leaf width × 0.6345).

[0135] (2) Determination of tobacco leaf appearance quality, physical properties, chemical composition, and aroma substances:

[0136] Appearance quality, physical properties, chemical composition and aroma substances are all in accordance with standard methods.

[0137] (3) Evaluation method of tobacco leaf sensory quality

[0138] A panel of seven tobacco industry sensory evaluation experts conducted sensory quality evaluations on tobacco leaf samples using the same evaluation criteria and methods as above.

[0139] The statistical effects of different nitrogen application rates, topping periods, and number of leaves left on the agronomic traits of tobacco leaves are shown in Table 15:

[0140] Table 15

[0141]

[0142] Note: The data with different lowercase letters in the table indicate significant differences (P<0.05). The same below.

[0143] Before topping and leaf retention, different nitrogen application rates had no significant effect on maximum leaf area. However, they had significant effects on plant height, number of effective leaves, and stem girth at 30 days. With increasing nitrogen application rates, plant height initially increased slowly and then significantly and rapidly, while the number of effective leaves increased slowly and then significantly and rapidly, and stem girth decreased significantly and then slowly. Under the same leaf retention number, increasing nitrogen application rates reduced the maximum leaf area in the middle and upper parts of the plant, the maximum leaf area of ​​the upper six leaves, and plant height. Under the same nitrogen application rate, with increasing leaf retention number, the maximum leaf area in the middle and upper parts of the plant gradually decreased, while plant height gradually increased. No significant pattern of changes in stem girth was observed. Among the three nitrogen application rates, A1 (N = 2 kg / mu) performed best. Topping at full flowering was the best treatment for topping. Among the three leaf retention levels, C1 (20 leaves) performed best.

[0144] The statistical effects of different nitrogen application rates, topping periods, and number of leaves left on the appearance quality of the top six tobacco leaves are shown in Table 16:

[0145] Table 16

[0146]

[0147] Table 16 shows that, at the same nitrogen application rate and different leaf number treatments, color, maturity, and leaf structure all showed a gradual improvement with increasing leaf number, while color and oil content showed a gradual decrease. Maturity and leaf structure reached their peak values ​​at A3, B3, and C3. At the same leaf number and different nitrogen application rates, most indicators showed an initial increase followed by a decrease with increasing nitrogen application rate. Overall, changes in various indicators with varying nitrogen application rates and leaf number showed that both had a significant impact on tobacco leaf appearance quality, but the impact of leaf number on appearance quality was less significant than that of nitrogen application rate. Overall, both nitrogen application rate and leaf number had a significant impact on tobacco leaf appearance quality, but nitrogen application rate was the primary influencing factor. The best results were achieved with a nitrogen application rate of 2 kg / mu, topping at peak flowering, and 22 leaves remaining.

[0148] The effects of different nitrogen application rates, topping periods, and number of leaves left on the physical properties of the top six tobacco leaves are shown in Table 17:

[0149] Table 17

[0150]

[0151] Table 17 shows that, at the same nitrogen application rate, with increasing leaf number, indicators such as leaf length, leaf weight, and equilibrium moisture content generally showed an upward trend. Leaf weight was greater in the A2B2C2 and A3B3C3 treatments than in the A1B1C1 treatment, while that in the A3B1C2 treatment was greater than that in the A1B2C3 and A2B3C1 treatments. Leaf weight in the A2B1C3 and A3B2C1 treatments was also greater than that in the A1B3C2 treatment. The above phenomenon was also observed in indicators such as leaf weight and equilibrium moisture content. At the same leaf number, with increasing nitrogen application rate, most indicators showed an upward and then downward trend. Leaf thickness in the A2B2C2 treatment was greater than that in the A2B3C1 and A2B1C3 treatments, and that in the A3B3C3 treatment was greater than that in the A3B1C2 and A3B2C1 treatments. However, the thickness in the A1B1C1 treatment was less than that in the A1B2C3 and A1B3C2 treatments. Comprehensively analyzing various indicators, different nitrogen application rates and number of leaves remaining affected tobacco leaf physical properties, but the effect of number of leaves remaining on these properties was less significant than that of nitrogen application rate. Overall, both nitrogen application rate and number of leaves remaining had significant effects on tobacco leaf physical properties, with nitrogen application rate being the primary influencing factor. The optimal nitrogen application rate of 2 kg / mu, topping at peak flowering, and 22 leaves remaining were found to be optimal.

[0152] The effects of different nitrogen application rates, topping periods, and number of leaves left on the chemical composition of the top six tobacco leaves are shown in Table 18:

[0153] Table 18

[0154]

[0155] As shown in Table 18, different nitrogen application rates and number of leaves left have a significant effect on the chemical composition of the top six tobacco leaves. At the same nitrogen application rate, between treatments with different number of leaves left, indicators such as total sugar, reducing sugar, total nitrogen, sugar-alkali ratio, nitrogen-alkali ratio, and potassium-chloride ratio generally showed a trend of first increasing and then decreasing, while nicotine and chlorine content generally showed a trend of first decreasing and then increasing, and potassium content did not change significantly. The nitrogen application rate at the A1 level was superior to that of the A2 and A3 treatments in all indicators of tobacco leaf chemical composition. At the same number of leaves left, with the increase in nitrogen application rate, total sugar, reducing sugar, potassium content, sugar-alkali ratio, nitrogen-alkali ratio, and potassium-chloride ratio generally showed a decreasing trend, while indicators such as nicotine and total nitrogen generally showed an increasing trend. The total sugar, reducing sugar, potassium content, total nitrogen, sugar-alkali ratio, and potassium-chloride ratio of the A2B2C2 treatment were superior to those of the A2B3C1 and A2B1C3 treatments. Nitrogen application rate and number of leaves retained significantly affected the chemical composition of tobacco leaves, but nitrogen application rate had a more significant impact on the chemical composition of tobacco leaves than did number of leaves retained. Comprehensively analyzing various indicators, nitrogen application rate and number of leaves retained had a significant impact on the upper six leaves. Nitrogen application rate was the primary influencing factor, with the optimal nitrogen application rate of 2 kg / mu, topping at peak flowering, and 22 leaves retained being optimal.

[0156] Nitrogen application rate and number of leaves left significantly affected the variety of aroma compounds in the upper six leaves. Seventeen aroma compounds were detected in A1B1C1, 29 in A2B2C2, 21 in A3B3C3, 21 in A1B2C3, 22 in A2B3C1, 23 in A3B1C2, 23 in A1B3C2, 19 in A2B1C3, and 23 in A3B2C1. Within treatments with the same nitrogen application rate but different leaf numbers, the variety of aroma compounds in the upper six leaves first increased and then decreased at low nitrogen application rates. With increasing nitrogen application rates, the variety of aroma compounds gradually increased, but the increase was modest. Within treatments with the same leaf number but different nitrogen application rates, the variety of aroma compounds in tobacco leaves also increased, but the increase was smaller than that due to the nitrogen application rate. In general, nitrogen application rate and number of leaves left had significant effects on the aroma substances in the upper six tobacco leaves, with nitrogen application rate being the main influencing factor. The best results were achieved when nitrogen application rate was 2 kg / mu, topping at full flowering and number of leaves left was 22.

[0157] The statistical effects of nitrogen application rate, topping period and number of leaves left on the sensory quality of the top six tobacco leaves are shown in Table 19:

[0158] Table 19

[0159]

[0160] Table 19 shows that among treatments with the same nitrogen application rate and different leaf number retention, overall sensory quality showed a downward trend with increasing leaf number retention. The sensory quality of the A2B2C2 treatment was higher than that of the A1B1C1 and A3B3C3 treatments, and the A1B2C3 treatment was higher than that of the A2B3C12 and A3B1C2 treatments. There was a slight difference in the N3 treatment, with the A3B2C1 treatment being superior to the A1B3C2 and A2B1C3 treatments. Among treatments with the same leaf number retention and different nitrogen application rates, there was an overall downward trend. The A1B1C1 treatment was superior to the A1B2C3 and A1B3C2 treatments, the A2B2C2 treatment was superior to the A2B3C1 and A2B1C3 treatments, and the A3B3C3 treatment was superior to the A3B1C2 and A3B2C1 treatments. With the increase of nitrogen application rate, the overall sensory evaluation of tobacco leaves under the three leaf number treatments showed a downward trend. Compared with the effect of leaf number on the sensory quality of tobacco leaves, the effect of nitrogen application rate on the sensory quality of tobacco leaves varied more. Nitrogen application rate was the main factor affecting the sensory quality of the upper six leaves. The best results were achieved with a nitrogen application rate of 2 kg / mu, topping at full flowering and 22 leaves.

[0161] Experiments conducted in the Jiangzhuang area to investigate the effects of varying nitrogen application rates and leaf counts on the quality of the top six leaves have yielded significant results. Field research revealed no significant differences in nitrogen application rates or leaf counts over the past three years in the Jiangzhuang area. Comprehensive evaluation of various tobacco leaf quality indicators revealed that the combination of a nitrogen application rate of 2 kg / mu, topping at peak flowering, and 22 leaves yielded the best results. This treatment, in particular, outperformed the other treatments in terms of chemical composition, aroma compounds, and sensory evaluation. In the experiment investigating the effects of varying nitrogen application rates and leaf counts on the quality of the top six leaves, the combination of a nitrogen application rate of 2 kg / mu, topping at peak flowering, and 22 leaves yielded the best leaf quality.

[0162] Effects of different fertilization methods on the quality of upper six tobacco leaves:

[0163] The experiment set up two treatments: CK was the control, i.e., conventional cultivation, and W1 was drip fertigation. A comparative experimental design was used, with a plot area of ​​0.135 mu, three replicates, and randomized plots. Details are shown in Table 20.

[0164] Table 20

[0165]

[0166] Conventional fertilization treatment CK: base fertilizer is compound fertilizer 10kg / mu; topdressing is compound fertilizer 10kg / mu, superphosphate 8.4kg / mu, Lop Nur potassium fertilizer 8kg / mu; 5 days before and after topping, Lop Nur potassium fertilizer is used to supplement the amount of potassium fertilizer by hole application, each time applying Lop Nur potassium fertilizer 8kg / mu, and irrigation is carried out at the same time after fertilization to ensure consistent watering amount.

[0167] Integrated water and fertilizer treatment W1: base fertilizer used was compound fertilizer 10 kg / mu; topdressing was compound fertilizer 10 kg / mu, superphosphate 8.4 kg / mu, and water-soluble potassium sulfate 7.69 kg / mu; 5 days before topping, water-soluble potassium sulfate fertilizer (N:P2O5:K2O=0:0:52) was used to supplement the potassium fertilizer dosage through integrated water and fertilizer, 3.84 kg / mu each time.

[0168] Results and Analysis:

[0169] Effects of different fertilization methods on agronomic traits of tobacco leaves:

[0170] To clarify the effects of different water and fertilizer treatments on tobacco plant agronomic traits, we monitored agronomic traits of tobacco plants at different treatment stages under different treatments. We found that the growth of tobacco plant agronomic traits showed different trends with the change in water and fertilizer application method. The plant height and stem girth of the W1 treatment were higher than those of the CK treatment and higher than the local level, reaching a significant difference of 0.05. By comparing the leaf area of ​​the middle, upper, and upper six leaves in the treatments 90 days after transplanting, we found that the middle and upper leaves of the W1 treatment showed better growth after topping.

[0171] The statistical effects of different fertilization methods on the appearance quality of the top six tobacco leaves are shown in Table 21:

[0172] Table 21

[0173]

[0174] Table 22 shows that different fertilization methods significantly affect tobacco leaf appearance. Integrated water and fertilizer drip irrigation significantly improves tobacco leaf appearance. Compared to the control group, treatment W1 showed improvements in leaf color, maturity, leaf structure, oil content, and chroma. Overall, treatment W1, or drip irrigation, significantly improves tobacco leaf appearance.

[0175] The statistical effects of different fertilization methods on the physical properties of the upper six tobacco leaves are shown in Table 22:

[0176] Table 22

[0177]

[0178] Table 23 shows that different fertilization methods significantly affect tobacco leaf physical properties. Integrated water and fertilizer drip irrigation can improve tobacco leaf physical properties. Compared with the control group, treatment W1 showed increases in leaf width, leaf mass, single leaf weight, filling value, and equilibrium moisture content, while slightly decreasing leaf length, stem content, tensile strength, and thickness. Overall, treatment W1, or drip irrigation, can significantly improve tobacco leaf physical properties.

[0179] The statistical effects of different fertilization methods on the chemical composition of the top six tobacco leaves are shown in Table 23:

[0180] Table 23

[0181]

[0182] Table 23 shows that, compared with conventional cultivation methods, the integrated drip irrigation method significantly impacted the chemical composition of tobacco leaves. Indicators such as total sugar, reducing sugar, potassium content, sugar-alkali ratio, and potassium-chloride ratio all increased, while nicotine, chlorine, and total nitrogen decreased. Overall, treatment W1, or the integrated drip irrigation method, significantly improved the chemical composition of tobacco leaves.

[0183] Integrated drip irrigation and fertilization significantly impacted the content of aromatic compounds in tobacco leaves. Twenty-four aromatic compounds were detected in the control group, while 30 were detected in the W1 treatment. Compared to the control group, the W1 treatment also detected ethyl acetate, valeraldehyde, hexanal, 6-methyl-5-hepten-2-one, 2-pentylfuran, maltol, and 6,10-dimethyl-5,9-undecadien-2-one. These compounds exhibited aromas of fruit, fermented bread, raw fat, and grass, apple, fruit, fresh, sweet, and fresh rose, respectively, adding a fruity and sweet aroma to the tobacco leaves. Overall, the W1 treatment, or integrated drip irrigation and fertilization, significantly increased the variety of aromatic compounds in the top six tobacco leaves.

[0184] The statistical effects of different fertilization methods on the sensory quality of the top six tobacco leaves are shown in Table 24:

[0185] Table 24

[0186]

[0187] Table 24 shows that the integrated fertigation drip irrigation significantly improved the sensory quality of the top six tobacco leaves. Compared to the control, treatment W1 showed improvements in aroma quality, volume, permeability, concentration, softness, and aftertaste, while reducing impurities and maintaining minimal irritation. Overall, treatment W1 (i.e., the integrated fertigation drip irrigation method) produced superior sensory quality for the top six tobacco leaves.

[0188] A pilot study in Jiangzhuang County investigated the effects of integrated fertigation and drip irrigation on the quality of tobacco leaves grown on the upper six leaves, yielding significant results. A survey revealed no significant differences in fertilization methods over the past three years. The W1 treatment achieved significant improvements in agronomic traits, physical properties, chemical composition, aroma compounds, and sensory evaluation of tobacco leaves compared to the control group. Overall, integrated fertigation and drip irrigation significantly improved the quality of tobacco leaves grown on the upper six leaves.

[0189] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for analyzing factors affecting the quality of six tobacco leaves, characterized in that: The following steps are involved: Tobacco planting experiments were conducted in different treatment groups with different biochar dosages, transplanting periods, nitrogen application rates, topping periods, number of leaves left, and fertilization methods. At different time points after transplanting tobacco leaves, the agronomic traits of tobacco plants were measured; Soil samples were collected near the roots of tobacco plants during the peak tobacco leaf growth period to analyze the diversity of soil microbial communities; Determine the appearance quality, physical properties, chemical composition and aroma substances of tobacco leaves; Sensory evaluation experts from the tobacco industry will conduct sensory quality evaluation on tobacco leaf samples; Based on the agronomic trait measurement results, the soil microbial community diversity, the appearance quality, physical properties, chemical composition and aroma substance measurement results and the sensory quality evaluation results, the effects of biochar dosage, transplanting period, nitrogen application amount, topping period and number of leaves left, and fertilization method on the quality of the top six tobacco leaves were determined respectively.

2. The method according to claim 1, characterized in that The soil microbial community diversity analysis includes the determination of Chao1, Shannon, Observed_species, Goods_coverage and OTUs indicators.

3. The method according to claim 1, characterized in that The agronomic traits include plant height, stem girth, maximum leaf length, leaf width and leaf area.

4. The method according to claim 1, wherein The appearance quality evaluation index includes color, maturity, leaf structure, identity, oil content and chroma; The physical properties measurement indicators include leaf length, leaf width, stem content, leaf weight, single leaf weight, tensile strength, thickness, filling value and equilibrium moisture content; The chemical composition determination indicators include total sugar, reducing sugar, nicotine, potassium, chlorine, and total nitrogen, and the sugar-alkali ratio, nitrogen-alkali ratio, and potassium-chlorine ratio are calculated; The determination of the aroma substances is carried out by gas chromatography-mass spectrometry to detect the types and contents of the aroma substances in the tobacco leaves.

5. The method according to claim 1, characterized in that The sensory quality evaluation indexes include aroma quality, aroma quantity, permeability, concentration, softness, aftertaste, miscellaneous smell, irritation, flammability and grayness.

6. The method according to claim 1, characterized in that The results of tobacco planting experiments with different biochar dosages showed that the best quality of the top six tobacco leaves was obtained when 1.0 t / mu of biochar was applied.

7. The method according to claim 1, characterized in that The results of tobacco planting experiments with different nitrogen application rates, topping periods and number of leaves left showed that the best tobacco quality was achieved with a nitrogen application rate of 2 kg / mu, topping at peak flowering and 22 leaves left.

8. The method according to claim 1, characterized in that The results of tobacco planting experiments with different fertilization methods showed that the quality of the top six tobacco leaves obtained by the integrated water and fertilizer drip irrigation method was the best.

9. The method according to claim 8, characterized in that The integrated water-fertilizer drip irrigation fertilization method includes: using 10 kg / mu of compound fertilizer as base fertilizer; topdressing with 10 kg / mu of compound fertilizer, 8.4 kg / mu of superphosphate, and 7.69 kg / mu of water-soluble potassium sulfate; using water-soluble potassium sulfate fertilizer with N:P2O5:K2O=0:0:52 five days before topping, and supplementing the potassium fertilizer dosage through the integrated water-fertilizer, 3.84 kg / mu each time.

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