A flue-cured tobacco planting method for improving the sweet and smooth feeling of tobacco leaves

Abstract

The application discloses a flue-cured tobacco planting method for improving sweet and moist feeling, and relates to the tobacco planting technical field.The base fertilizer and cake fertilizer are uniformly mixed and are applied in strips before tobacco transplanting, and the topdressing fertilizer and cake fertilizer are uniformly mixed and are applied in strips before tobacco bunching, the base fertilizer comprises magnesium hydroxide, calcium-magnesium phosphate, tobacco special fertilizer and potassium nitrate, the topdressing fertilizer comprises tobacco special fertilizer, potassium nitrate and potassium sulfate, and the cake fertilizer comprises sesame cake.The base fertilizer and topdressing fertilizer are mixed with the cake fertilizer when being applied, the content of solanesol and palmitic acid in flue-cured tobacco leaves can be effectively improved, and the sweet and moist feeling of the flue-cured tobacco can be obviously improved.

Description

Technical Field

[0001] This invention relates to the field of tobacco cultivation technology, specifically providing a method for cultivating flue-cured tobacco to improve the sweetness and juiciness of tobacco leaves. Background Technology

[0002] The sweetness is one of the evaluation contents of the taste (the general term for the sour, sweet, bitter, astringent and other tastes reflected in the mouth after smoking) in the sensory evaluation of tobacco leaves. It is often described in the internal quality evaluation of tobacco leaves with words such as "the aftertaste is relatively clean and comfortable, with a sweet and refreshing feeling, no residue in the mouth and no obvious dryness" to reflect the sensory experience of sweetness. It is an important evaluation content of sensory quality.

[0003] Due to the prevalent aroma preferences in cigarette formulations, the aroma style, especially the aroma characteristics, of flue-cured tobacco has received increasing attention in industrial applications in recent years. Sensory quality largely determines the industrial usability of flue-cured tobacco. Different aroma types of flue-cured tobacco exhibit variations in sensory quality due to differences in regional ecological conditions, cultivation techniques, and other factors, as well as differences in the content of chemical components in the tobacco leaves. Improving the sweetness and smoothness of flue-cured tobacco is a pressing issue that needs to be addressed in tobacco cultivation. Summary of the Invention

[0004] This invention provides a method for cultivating flue-cured tobacco to improve the sweetness and juiciness of tobacco leaves by changing the fertilization method.

[0005] The technical solution of the present invention is as follows:

[0006] A method for improving the sweetness and juiciness of flue-cured tobacco leaves involves uniformly mixing basal fertilizer and oilseed cake fertilizer, applying the mixture in strips before transplanting and topdressing before the tobacco plants cluster together. The basal fertilizer includes magnesium hydroxide, calcium magnesium phosphate, tobacco-specific fertilizer, and potassium nitrate. The topdressing fertilizer includes tobacco-specific fertilizer, potassium nitrate, and potassium sulfate. The oilseed cake fertilizer includes sesame cake. In this method, after uniformly mixing the basal fertilizer and oilseed cake fertilizer and applying them, analysis of the middle leaves (the 10th-11th leaves from the bottom up) at harvest reveals a significant increase in sweetness and juiciness. Near-infrared spectroscopy analysis of the chemical composition of these leaves shows a significant increase in solanone and palmitic acid content compared to tobacco leaves grown under conventional basal and topdressing conditions. By increasing the content of solanone and palmitic acid, the sweetness and juiciness of the flue-cured tobacco are improved.

[0007] Preferably, the organic matter content of the oilseed cake is ≥70%, and the ratio of total nitrogen:total phosphorus:total potassium is 10.14:1.59:1. The composition ratio of commercially available sesame cake matches this ratio, allowing for direct purchase of commercially available sesame cake without additional processing, thus reducing the difficulty of obtaining oilseed cake.

[0008] Preferably, the amount of oilseed cake applied each time is 0.75 t / hm. 2 The total nitrogen content of the base fertilizer and oilseed cake fertilizer is 0.143 t / hm.2 The total nitrogen content of the topdressing and oilseed cake fertilizer is 0.143 t / hm. 2 .

[0009] Preferably, the base fertilizer and oilseed cake are mixed with the soil, and the base fertilizer and oilseed cake are applied in strips at a depth greater than 20cm. In this scheme, the depth of application of base fertilizer and oilseed cake in strips greater than 20cm can avoid fertilizer being exposed on the soil surface, thus preventing nitrogen volatilization and oilseed cake from absorbing moisture and clumping, ensuring that the fertilizer is fully mixed into the soil, so that the tobacco seedlings can obtain sufficient fertilizer after transplanting.

[0010] Preferably, flue-cured tobacco is planted in ridges in the tobacco field, and the base fertilizer and oilseed cake fertilizer are applied in strips between any two ridges.

[0011] Preferably, after applying the base fertilizer and oilseed cake in strips, wait at least 7 days before transplanting the tobacco seedlings. In this plan, applying the base fertilizer and oilseed cake in strips allows the oilseed cake to integrate with the soil, reducing fertilizer damage, and also allows the oilseed cake to decompose in advance, slowly releasing nutrients after transplanting to match the growth of the tobacco seedlings.

[0012] To address the issue of oilseed cake fermenting after strip application, which can lead to seedling or root burn, this method includes a composting process for the oilseed cake before mixing it with the base fertilizer. The composted oilseed cake is then mixed with the base fertilizer. In this solution, the oilseed cake is composted before being mixed with the base fertilizer. Fermentation is completed during the composting process, preventing post-application fermentation that could cause seedling or root burn.

[0013] To address the issue of uneven composting of oilseed cake, which leads to fermentation of uncooked cake after fertilization, the composting process includes crushing, adding water to moisten, piling the cake into heaps and covering it with a film, and then fermentation. In this method, crushing the oilseed cake allows for better contact with air, which is beneficial for fermentation. Piling the cake into heaps and covering it with a film helps to retain heat, resulting in higher composting efficiency. Simultaneously, the high temperature helps to kill insect eggs in the oilseed cake.

[0014] To address the issue of declining tobacco quality due to rising temperatures, this method is implemented in subtropical monsoon climates by reducing the number of leaves retained to 17 during topping. In this approach, controlling the number of leaves retained to 17 significantly improves the sweetness and smoothness of the tobacco. Furthermore, retaining 17 leaves yields the optimal effect on enhancing the sweetness and smoothness of the tobacco compared to further reducing the number of leaves.

[0015] To address the issue of declining tobacco quality due to rising temperatures, this method is implemented in subtropical monsoon climates, advancing the tobacco transplanting time by 7-14 days. In this scheme, while maintaining the same seedling period, earlier transplanting allows for harvesting at a more favorable temperature range, thereby improving tobacco quality.

[0016] The beneficial effects of this invention are:

[0017] This invention, when used in combination with oilseed cake fertilizer during the application of base fertilizer, can effectively increase the content of solanone and palmitic acid in flue-cured tobacco leaves, and significantly improve the sweetness of flue-cured tobacco. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 To compare the sensory quality evaluation forms of tobacco leaves from each group in Experiment 1;

[0020] Figure 2 For comparison, see the standard chemical composition analysis tables for each group in Experiment 1;

[0021] Figure 3 For comparison, see the aroma component analysis table for each group in Experiment 1;

[0022] Figure 4 To compare the routine chemical composition analysis of each group in Experiment 2;

[0023] Figure 5 To compare the sensory quality evaluation forms of tobacco leaves in each group of Experiment 2;

[0024] Figure 6 The table shows the analysis of aroma components in each group of Experiment 2 for comparison. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings and through specific embodiments of the present invention.

[0026] Example 1:

[0027] like Figure 1 As shown in the figure, this embodiment provides a method for cultivating flue-cured tobacco to improve the sweetness and savory flavor of tobacco leaves, including the following steps:

[0028] S1. Before transplanting the Yunyan 87 tobacco seedlings, ridges were created in the tobacco field to form raised beds. The basic physical and chemical properties of the tobacco field soil were as follows: soil pH value was 6.12, and organic matter content was 23.6 g•kg. -1 Alkaline nitrogen content: 105.8 mg·kg -1 Available phosphorus 58.68 mg·kg -1 155.32 mg / kg of readily available potassium -1The raised beds are used for transplanting tobacco seedlings. Furrows are formed between the raised beds, and a uniform mixture of base fertilizer and oilseed cake is applied to the furrows. This means the base fertilizer and oilseed cake are evenly mixed and then applied in rows in the tobacco field. During the row application process, fertilization furrows 20-25cm deep are dug along the trenches. The base fertilizer and oilseed cake are evenly applied into the furrows. After fertilization, the furrows are covered with soil so that the base fertilizer and oilseed cake are more than 20cm below the ground level. S2. Seven days after the row application of base fertilizer and oilseed cake, the Yunyan 87 tobacco seedlings are transplanted. Two rows of Yunyan 87 seedlings are transplanted on each side of the raised bed, meaning two rows of seedlings are planted per raised bed.

[0029] S3. Before Yunyan 87 grows into a cluster, apply topdressing fertilizer in holes between the ridges. Dig holes about 10cm (8-12cm) deep on the ridges, 10-15cm away from the stem of Yunyan 87, apply the topdressing fertilizer into the holes, and then fill the holes with soil.

[0030] In step S1 above, the base fertilizer includes magnesium hydroxide, calcium magnesium phosphate, tobacco-specific fertilizer, and potassium nitrate. The oilseed cake includes commercially available sesame cake. Commercially available sesame cake has an organic matter content of ≥70% and a total nitrogen:total phosphorus:total potassium ratio of 10.14:1.59:1. When mixing the base fertilizer and oilseed cake, ensure the total nitrogen application rate is 0.143 t / hm². 2 Furthermore, the application rate of oilseed cake fertilizer was 0.75 t / hm. 2 The mass ratio of various fertilizers is as follows: cake fertilizer: magnesium hydroxide: calcium magnesium phosphorus: tobacco-specific fertilizer: potassium nitrate = 1:0.25:0.3:0.74:0.1.

[0031] Before using oilseed cake, it needs to be decomposed. This decomposition process includes crushing the cake, adding water to moisten it, piling it into a heap, covering it with a film, and fermenting it for 20-30 days (turning the heap once during fermentation). Decomposed oilseed cake avoids re-fermentation after application, which can cause root and seedling burn in tobacco plants.

[0032] When crushing oilseed cake, it can be ground into a fine powder with a diameter of 5-8mm. This fine powder allows for more even mixing and improves fermentation efficiency. By increasing fermentation efficiency, the temperature can be uniformly and quickly reached above 55℃ during fermentation, a temperature sufficient to kill insect eggs.

[0033] To improve temperature stability, black film can be used when covering the compost pile. Black film has strong heat absorption capacity but is opaque, which can prevent direct sunlight from causing the temperature of the compost pile to rise rapidly to above 70℃. When the temperature of the compost pile rises above 70℃, the oilseed cake will become ineffective. Although transparent film can significantly accelerate fermentation efficiency, it is also prone to causing the oilseed cake to become ineffective due to high temperatures. Therefore, black film is preferred.

[0034] When laying the black plastic film, rod-shaped or tubular structures can be placed on top of the compost pile to create space between the film and the pile, allowing airflow and enabling the compost to contact oxygen for fermentation. One end of the rod-shaped or tubular structure extends beyond the black plastic film, and the connection between the film and the structure is not sealed, allowing outside air to enter the film through the structure. These structures create airflow channels within the film, ensuring ample oxygen contact and allowing waste gases from fermentation to escape, thus promoting high-temperature decomposition rather than rotting. The rod-shaped or tubular structures also provide internal support for the film, ensuring the stability of the airflow channels.

[0035] As an optional technical solution, a ring of quicklime can be laid around the edge of the compost pile to adjust the pH value of the oilseed cake. The water vapor produced during oilseed cake fermentation condenses and comes into contact with the quicklime. The quicklime reacts with water to generate heat, which heats the bottom layer of oilseed cake. This makes the fermentation speed of the bottom layer of oilseed cake closer to the center or top of the compost pile, resulting in a more uniform fermentation speed and improved fermentation efficiency. During compost pile fermentation, the temperature dissipates most slowly in the center, reaching above 55℃ more quickly and achieving the highest decomposition efficiency. The surface layer, in contact with the air, dissipates heat quickly, and its temperature rises more slowly than the center. The bottom layer, directly exchanging heat with the ground, experiences the slowest temperature increase. Laying quicklime around the edge of the compost pile allows the heat generated by the reaction of quicklime and water to heat the ground, thus accelerating the temperature rise of the bottom layer of oilseed cake. Because the quicklime is located around the circumference of the compost pile, the heat generated is also transferred to the surface layer through the air, heating the surface and resulting in a more uniform temperature rise and more consistent decomposition efficiency throughout the entire compost pile. The mass ratio of oilseed cake to quicklime can be 100:1-2.

[0036] During the composting process of oilseed cake, quicklime should be laid on top only after the compost pile is formed and there is no moisture seepage from the edges. This prevents quicklime from mixing into the compost pile during its formation and also avoids premature reaction caused by moisture seepage. As an alternative, quicklime can be placed in small buckets, with the bottom of the buckets buried at the edge of the compost pile. This delays the reaction of the quicklime, allowing the surface and bottom layers of oilseed cake to heat up first using the temperature generated by fermentation within the pile. Then, the moisture from fermentation reacts with the quicklime in the buckets to generate heat, which is transferred from the ground and air to the surface and bottom layers, further raising their temperature to be closer to that of the compost in the center of the pile, resulting in more uniform composting. The bucket method also avoids direct contact between quicklime or reacted slaked lime and the oilseed cake, allowing for the use of more quicklime for heating. After the oilseed cake is fully composted, the appropriate weight of slaked lime is weighed out. This method improves heat generation capacity, enhances temperature control of the oilseed cake, and allows for precise control of the amount of slaked lime added.

[0037] Using quicklime makes the temperature of the compost pile more uniform, and the degree of decomposition of the cake fertilizer in the compost pile more uniform. This can avoid secondary fermentation after the cake fertilizer is mixed with the base fertilizer and applied in strips, and avoid secondary fermentation that could burn the tobacco seedlings or roots.

[0038] In step S3 above, the topdressing includes tobacco-specific fertilizer, potassium nitrate, and potassium sulfate. The total nitrogen application rate for topdressing is 0.143 t / hm². 2 .

[0039] The width of the raised beds in the tobacco field is 1.2-1.5m, and the width of the strip application of the base fertilizer and cake fertilizer is 15-20cm. The width of the raised beds refers to the distance between the tops of two raised beds. This distance allows for the growth of two rows of Yunyan 87 plants on one raised bed. Furthermore, the width of the strip application of the base fertilizer and cake fertilizer ensures that the taproot of Yunyan 87 will not directly contact the fertilizer in the soil, thus avoiding root burn and rot caused by direct contact with high concentrations of fertilizer.

[0040] When applying fertilizer in holes, the depth of the fertilizer hook should be less than 5cm to avoid damaging the plant's root system.

[0041] Example 2:

[0042] This second embodiment provides a method for improving the sweetness of tobacco in the southeastern coastal region. Unlike embodiment one, the transplanting time and the number of leaves retained are different in this second embodiment.

[0043] Temperatures in the southeastern coastal region are showing an overall upward trend. Taking the cultivation of Yunyan 87 tobacco in Fujian, a region with a subtropical monsoon climate, as an example, tobacco seedlings are cultivated in seedling sheds for 55-60 days before transplanting, usually around the winter solstice, with harvesting in May and June. However, with rising temperatures, the temperature during transplanting in these areas has increased from 5-10℃ to around 12℃, and the highest temperature during harvesting has exceeded 28℃. Both the transplanting and harvesting temperatures exceed the optimal range, resulting in a decrease in the quality of the obtained tobacco leaves, with a poor sweetness score of 6.0.

[0044] Therefore, in one cultivation group, for tobacco planting in this region, Example 2 maintains the number of days of seedling cultivation, but advances the planting and transplanting dates of the seedlings by 7-14 days, which corresponds to earlier tobacco leaf maturity and harvesting dates, resulting in a significant increase in the sweetness of the obtained tobacco leaves, with a sweetness score of 6.5.

[0045] In another cultivation group, the number of leaves retained during topping was reduced to 17 leaves (compared to the usual 18 leaves). The resulting tobacco leaves also exhibited improved sweetness, achieving a sweetness score of 6.5.

[0046] In another cultivation group, cake fertilizer was applied in accordance with the fertilizer composition and ratio of Example 1, which also resulted in tobacco leaves with increased sweetness and a sweetness score of 6.5.

[0047] When the three cultivation groups were combined, it was found that simultaneously transplanting earlier and reducing the number of leaves left did not significantly increase the sweetness of the tobacco leaves, and the sweetness score of the harvested tobacco leaves remained at 6.5.

[0048] At the same time, with early transplanting and increased application of cake fertilizer, the sweetness score of the harvested tobacco leaves remained at 6.5.

[0049] At the same time, by reducing the number of leaves left and increasing the application of cake fertilizer, the sweetness score of the harvested tobacco leaves remained at 6.5.

[0050] However, by simultaneously transplanting earlier, reducing the number of leaves left, and increasing the application of cake fertilizer, the sweetness of the harvested tobacco leaves was significantly improved, with the sweetness score rising to 7.0.

[0051] Comparative Experiment 1:

[0052] The technical solution of this embodiment is compared with biochar and organic bio-fertilizer in commonly used organic materials. Taking the technical solution of this embodiment as T1, this comparative experiment provides a conventional control group CK, a biochar control group T2 and a bio-organic fertilizer control group T3.

[0053] CK: For Yunyan 87 tobacco seedlings, only base fertilizer is applied before transplanting, and only top dressing is applied before the seedlings are formed.

[0054] T1: For Yunyan 87 tobacco seedlings, apply a mixture of base fertilizer and oilseed cake fertilizer before transplanting, and only apply top dressing before the seedlings form crowns. The amount of oilseed cake fertilizer applied is 0.75 t / hm. 2 .

[0055] T2: For Yunyan 87 tobacco seedlings, apply a mixture of base fertilizer and biochar before transplanting, and only apply top dressing before the seedlings form crowns. The biochar composition includes 45.81% organic carbon and a total nitrogen:total phosphorus:total potassium ratio of 1:1.22:2.06. The biochar application rate is 1.5 t / hm². 2 .

[0056] T3: For Yunyan 87 tobacco seedlings, apply a mixture of base fertilizer and bio-organic fertilizer before transplanting, and only apply top dressing before the seedlings form crowns. The bio-organic fertilizer should contain ≥0.2 billion live bacteria per gram, ≥40% organic matter, and a total nitrogen:total phosphorus:total potassium ratio of 1.62:1:2.19. The application rate of bio-organic fertilizer is 0.75 t / hm². 2 .

[0057] In CK, T1, T2, and T3, the total nitrogen application rate was maintained at 0.143 t / hm. 2Based on the different proportions of each component in cake fertilizer, biochar, and organic bio-fertilizer, the proportions of various fertilizers in the base fertilizer and top dressing are adjusted to maintain consistent nitrogen application and nitrogen-phosphorus-potassium ratios in each treatment.

[0058] The tobacco field conditions were identical in all experiments, using soil pH 6.12 and organic matter content 23.6 g•kg as described in Implementation 1. -1 Alkaline nitrogen content: 105.8 mg·kg -1 Available phosphorus 58.68 mg·kg -1 155.32 mg / kg of readily available potassium -1 Tobacco fields.

[0059] During the comparative testing, the middle leaves (the 10th-11th leaves from the bottom up) were taken at harvest for tobacco quality analysis. The analysis included aroma quality, aroma quantity, transparency, off-flavors, fineness, smoothness, roundness, irritation, dryness, aftertaste, and sweetness. The total score was obtained by combining the scores of the above items. The technical solution in Implementation 1 achieved the highest total score for the tobacco.

[0060] Analysis results as follows Figure 1 The sensory quality evaluation table for tobacco leaves shown in the figure indicates that...

[0061] The evaluation results showed that the tobacco leaves treated with the T1 method had a significantly higher sweetness and smoothness than those treated with CK, T2, and T3. Applying sesame cake in addition to conventional fertilization increased the sweetness and smoothness, as well as the scores for irritation and aftertaste. The tobacco leaves treated with conventional fertilization plus biochar and conventional fertilization plus bio-organic fertilizer showed increased aroma and sweetness. After comprehensive comparison, the flue-cured tobacco treated with basal fertilizer and topdressing in combination with sesame cake achieved the highest overall score.

[0062] Similarly, the middle leaves (the 10th-11th leaves from the bottom up) were roasted, and the roasted tobacco leaves were subjected to routine chemical composition analysis. The routine chemical composition of the samples was determined by near-infrared scanning. According to the established near-infrared prediction model, the contents of nicotine, reducing sugar, total sugar, potassium, total nitrogen, chlorine, and starch in the samples were determined, and the ratio of two sugars, sugar-alkali ratio, and potassium-chlorine ratio were calculated.

[0063] from Figure 2 The conventional chemical composition analysis table shows significant differences in the chemical composition of tobacco leaves among different treatments. Nicotine content was higher in the control group (CK); reducing sugar content was higher in CK and T2; total sugar and total nitrogen content were higher in T1 and T2, respectively, with no significant differences among treatments; potassium content was higher in T2 and T3; chlorine content was highest in T2; and starch content was highest in T1 and lowest in T2. ​​Regarding tobacco leaf balance, the sugar-to-nicotine ratio was higher in T2; the sugar-to-nicotine ratio was higher in T1, significantly higher than CK, T2, and T3; the potassium-to-chlorine ratio was highest in T3 and lowest in T2. ​​Overall, T1 and T3 showed slightly better chemical composition than the other treatments.

[0064] Among them, the sugar-alkali ratio is the first core indicator of tobacco quality, reflecting the balance between "sweet substances" and "irritating substances". It directly determines whether the smoke is smooth, sweet and without a harsh throat sensation, and is the core criterion for judging the sweetness.

[0065] The ratio of the two sugars reflects the proportion of the two types of soluble sugars in tobacco leaves. Soluble sugars are the direct material basis for the sweetness of tobacco leaves, and the ratio of the two types of sugars determines whether the sweetness is "sweet and mellow" or "bland and simple".

[0066] The potassium-chlorine ratio is a crucial baseline indicator for tobacco quality, as tobacco is sensitive to chlorine and prefers potassium. This ratio directly reflects whether the tobacco leaves can burn completely without extinguishing the fire and whether the ash is white. Combustion is fundamental to the release of sweetness. Incomplete combustion prevents the effective release of sweet substances and can also produce off-flavors.

[0067] A comprehensive comparison of the sugar-to-alkali ratio, the ratio of two sugars, and the potassium-to-chloride ratio shows that the sugar-to-alkali ratio of scheme T1 is significantly higher than that of CK, T2, and T3, directly affecting the sweetness of the flue-cured tobacco. Furthermore, T1's potassium-to-chloride ratio is also at a high level; the top-quality potassium-to-chloride ratio in tobacco is >8:1, and T1's tobacco reaches a top-quality level in this ratio, satisfying the release of sweetness. Therefore, the technical solution in Example 1 is the most effective in enhancing the sweetness of Yunyan 87.

[0068] Combined Figure 3 The analysis table of aroma components shows that there are significant differences in the aroma components of the middle tobacco leaves among different treatments, with the contents of each component in T1, T2, and T3 being higher than those in CK. 4,7,9-Giantazolidin-3-one is a key aroma compound in tobacco, possessing a distinct sweet and floral aroma. Solanone can enhance the sweetness, while (4,5,5-trimethyl-1,3-cyclopentadien-1-yl)benzene is an aromatic compound, often with a woody and sweet aroma. Palmitic acid can enhance the smoothness, and neophyte degradation products contribute to the sweetness and have an oily feel. T1 has higher contents of solanone, palmitic acid, and neophyte, while T2 has higher contents of 4,7,9-Giantazolidin-3-one and (4,5,5-trimethyl-1,3-cyclopentadien-1-yl)benzene.

[0069] Solanone increases sweetness, and palmitic acid enhances smoothness. The content of solanone and palmitic acid in T1 is much higher than that in CK, T2 and T3, which can significantly increase the sweetness of flue-cured tobacco.

[0070] Comparative Experiment 2:

[0071] The technical solution of Example 2 is compared with that of tobacco cultivated in Fujian Province according to conventional methods.

[0072] The conventional cultivation group CK1 was set up, transplanted at the winter solstice, with 18 leaves retained as usual, and fertilized as usual.

[0073] In the control group T11, the number of leaves retained was reduced to 17.

[0074] The control group, T12, underwent transplantation 7 days earlier.

[0075] The control group T13 had 17 leaves remaining and was transplanted 7 days earlier.

[0076] The control group, T14, received additional cake fertilizer.

[0077] The control group T15, with increased application of cake fertilizer, had its number of leaves reduced to 17.

[0078] The control group, T16, received additional cake fertilizer and was transplanted 7 days earlier.

[0079] The control group T17 received increased application of cake fertilizer, had its number of leaves reduced to 17, and was transplanted 7 days earlier.

[0080] In the control group T18, the number of leaves retained was reduced to 16.

[0081] The control group T19 had 16 leaves retained and were transplanted 7 days earlier.

[0082] The control group T20 received increased application of cake fertilizer, had fewer leaves remaining (to 16 leaves), and was transplanted 7 days earlier.

[0083] The tobacco leaf scores of the conventional cultivation group (CK1) and the control group (T11 to T17) were analyzed separately. The comparison results are as follows: Figure 4 As shown in the table of conventional chemical composition analysis for Experiment 2, the control group T17 had the highest sugar-to-alkali ratio, significantly higher than other groups. T13 and T17 had the lowest nicotine content, around 2.4%. This indicates that transplanting 7 days earlier and reducing the number of leaves to 17 can significantly reduce nicotine content. This application further obtained the highest sugar-to-alkali ratio tobacco leaves by increasing the application of cake fertilizer, combined with reducing the number of leaves to 17 and transplanting 7 days earlier. Comparing T18 with T11, and T17 with T20, it was found that further reducing the number of leaves actually reduced the improvement in the sugar-to-alkali ratio, indicating that retaining 17 leaves is a better choice.

[0084] like Figure 5 As shown in the sensory quality analysis table of Experiment 2, the sweetness score of control group T17 was 7.0, significantly higher than other groups. This directly reflects that the cultivation method of control group T17 can significantly improve the sweetness of tobacco leaves in this region. Comparing T11 and T18, and T13 and T19, with only the number of leaves retained as a single variable, further reducing the number of leaves to 16 leaves did not significantly change the quality of the tobacco leaves. Comparing T20 and T17, it can be seen that T20 did not improve the sweetness of the tobacco leaves as much as T17, indicating that retaining 16 leaves did not improve the sweetness of the tobacco leaves as much as retaining 16 leaves, suggesting that retaining 17 leaves is the optimal number for improving sweetness.

[0085] like Figure 6 As shown in the comparative experiment 2's aroma component analysis table, the proportions of solanone and neophytadiene in control group T17 were significantly higher than in other groups, and the total amount of aroma components was also significantly higher. Especially considering the significant decrease in aroma component content in control groups T15 and T16, control group T17 unexpectedly and significantly increased the aroma components in tobacco leaves. Comparing T15 and T18, T16 and T19, and T17 and T20, it can be found that when the number of leaves retained is further reduced to 16, the total amount of aroma components in the tobacco leaves actually decreases. This fully demonstrates that when the number of leaves retained is 17, the cultivated tobacco leaves have more aroma components and better quality. Furthermore, comparing the total amount of aroma components in T18 and T19 with that in T20, it can be found that the total amount of aroma components in T20 is significantly higher than that in T18 and T19, indicating that the combination of applying cake fertilizer, reducing the number of leaves retained, and early transplanting can unexpectedly produce tobacco leaves of better quality. The total amount of aroma components in T18 and T19 is also much lower than that in T14, indicating that reducing the number of leaves to 16 is actually less effective than applying only cake fertilizer. This suggests that even with cake fertilizer and early transplanting, reducing the number of leaves to 16 will still result in a decrease in the total amount of aroma components in the tobacco leaves. Therefore, considering both sweetness and the total amount of aroma components, it can be determined that retaining 17 leaves is the optimal choice.

Claims

1. A method for cultivating flue-cured tobacco to improve the sweetness and savory flavor of tobacco leaves, characterized in that, The base fertilizer and cake fertilizer are evenly mixed and applied in strips before tobacco transplanting, and topdressing is applied in holes before the tobacco plants are clustered together. The base fertilizer includes magnesium hydroxide, calcium magnesium phosphate, tobacco-specific fertilizer and potassium nitrate. The topdressing includes tobacco-specific fertilizer, potassium nitrate and potassium sulfate. The cake fertilizer includes sesame cake.

2. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 1, characterized in that, The organic matter content of the oilseed cake is ≥70%, and the ratio of total nitrogen: total phosphorus: total potassium is 10.14:1.59:

1.

3. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 1, characterized in that, The amount of oilseed cake fertilizer applied each time is 0.75 t / hm. 2 The total nitrogen content of the base fertilizer and oilseed cake fertilizer is 0.143 t / hm. 2 The total nitrogen content of the topdressing is 0.143 t / hm. 2 .

4. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 1, characterized in that, The base fertilizer and oilseed cake are mixed with the soil, and the base fertilizer and oilseed cake are applied in strips at a depth of more than 20cm.

5. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 4, characterized in that, Tobacco fields are planted on raised beds, with the base fertilizer and oilseed cake applied in strips between two adjacent raised beds.

6. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 1, characterized in that, After applying base fertilizer and oilseed cake fertilizer in strips, wait at least 25-35 days before transplanting the flue-cured tobacco seedlings.

7. The method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 1, characterized in that, Before mixing the oilseed cake with the base fertilizer, the oilseed cake undergoes a composting process, after which it is mixed with the base fertilizer.

8. A method for improving the sweetness and juiciness of flue-cured tobacco leaves according to claim 7, characterized in that, The composting process of oilseed cake includes crushing, adding water to moisten it, piling it up and covering it with a film, and fermentation.

9. A method for cultivating flue-cured tobacco to improve the sweetness and juiciness of tobacco leaves according to claim 7, characterized in that, The method is implemented in a subtropical monsoon climate, reducing the number of leaves to 17 when topping tobacco.

10. A method for cultivating flue-cured tobacco to improve the sweetness and juiciness of tobacco leaves according to claim 7, characterized in that, The method is implemented in subtropical monsoon climates, advancing the tobacco transplanting time by 7-14 days.

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