Method for baking tobacco leaves in the upper part of white eel mud tobacco field

Abstract

The present invention discloses a method for baking tobacco leaves on the upper part of a white eel mud tobacco field. The method comprises the following steps: spraying a nutrient solution on the leaves before harvesting, appropriately reducing the maturity of tobacco leaves during harvesting, appropriately reducing the amount of tobacco leaves to be woven, reducing the density of tobacco leaves to be loaded on a kang, adopting a baking technology of high temperature main yellowing, early dehumidification in the later stage of yellowing, and gradually reducing the wet-bulb temperature during baking, reducing the yellowing degree of tobacco leaves during switching to another fire, adopting a low temperature, low humidity, slow temperature rise baking technology for color fixing during the color fixing period, gradually increasing the wet-bulb temperature in the early stage of color fixing, and adopting a fast drying baking technology in the dry-stem period. By adopting the method for baking tobacco leaves on the upper part of a white eel mud tobacco field, the difficulty of color fixing of the upper tobacco leaves can be effectively reduced, the ash on the upper tobacco leaves can be reduced, and the appearance quality and intrinsic quality of the tobacco leaves after baking can be improved.

Description

Technical Field

[0001] The invention relates to a method for baking tobacco leaves on the upper part of a white eel mud tobacco field, belonging to the technical field of baking tobacco leaves on the upper part. Background Art

[0002] The fundamental formation process of bleached mud is the reductive leaching of free iron and manganese, also known as bleaching. The underlying conditions for this process are stagnant water in the soil and the presence of organic reducing agents, both of which are primarily determined by the parent material and topographical conditions. While bleaching manifests as a whitening of the soil, the underlying change is the reductive leaching of free iron. Free iron is the primary mineral colorant in soil, and its significant leaching inevitably leads to soil bleaching. Manganese is also a colorant and undergoes reductive leaching, but its presence in soil is low, making its significance less significant.

[0003] The plow and plough layers of the white eel mud fields are lumpy or blocky; the bleaching layer is prismatic, with small iron and manganese patches found throughout. The soil is clayey, pebbly, and mostly loamy clay. Its pH is generally below 5.5, indicating acidity. Bleached soil is present throughout, with the bleaching layer at depths of 30-60 cm. The soil is nutrient-deficient, with low levels of total and available phosphorus and potassium, particularly in the bleaching layer. Zinc is deficient in available trace elements, while boron and molybdenum levels are below critical deficiency levels.

[0004] The soil characteristics of white eel mud fields are "sticky, sour, cold, thin, and especially lacking in phosphorus". This type of soil is relatively sticky, and land preparation is laborious. The tillage period is short, the tillage properties are poor, the tillage layer is shallow, the tillage properties and permeability are poor, and the nutrients are poor. It has the characteristics of being "sticky, sour, thin, stiff, and hard". For a long time, it has been collectively referred to as low-yield fields. The actual fertilizer supply capacity of white eel mud is low, and there is an imbalance between the various nutrients. Therefore, fertilization must be adjusted to obtain high crop yields. Through some improvement and fertilization measures, the fertility level of white eel mud fields has been improved. However, most white eel mud fields are still at a medium to low fertility level. The production performance of white eel mud fields is restricted by their fertility characteristics, mainly: poor soil structure, poor permeability, unbalanced soil nutrients, and uncoordinated supply.

[0005] The upper leaves of the Baichenni tobacco fields refer to the top 4-6 leaves of the tobacco plants grown there. Currently, these leaves are cured using conventional local curing techniques. However, this technique makes it very difficult, if not impossible, to fix the color of the leaves during curing, and results in significant ash buildup. This results in poor visual and internal quality of the cured leaves, and no significant technical breakthroughs have been achieved. Research and improvement are necessary. Summary of the Invention

[0006] Based on the above, the present invention provides a method for baking tobacco leaves in the upper part of a white eel mud tobacco field to overcome the shortcomings of the prior art.

[0007] The technical solution of the present invention is: a method for baking tobacco leaves in the upper part of a white eel mud tobacco field, comprising:

[0008] S1, spraying: spraying nutrient solution on the leaves of the upper part of the tobacco leaves in the white eel mud field 1 to 2 days before harvesting. This method can coordinate the nutritional balance of the upper tobacco leaves and improve the baking resistance of the tobacco leaves.

[0009] S2, harvesting: The upper fresh tobacco leaves are harvested when they are physiologically mature. The harvesting maturity is 10% to 30% lower than the normal maturity. The leaves are mainly yellow, with the yellow area of ​​the leaves accounting for 50% to 70%. The main veins are white, more than half of the side veins are white, and most of the hairs fall off. This method can reduce the harvesting maturity of tobacco leaves, reduce the consumption of substances contained in tobacco leaves in the field, and improve the baking resistance of tobacco leaves.

[0010] S3, Bunching: Tobacco leaves are sorted into three categories based on maturity: physiologically mature, mature, and fully mature. Each bundle is then bundled into 130-160 leaves. Bunching improves the uniformity and synchronicity of tobacco quality. Reducing the amount of bundled tobacco improves ventilation and moisture removal efficiency in the densely packed flue-curing barn, easing the difficulty of coloring the leaves and reducing ash buildup, thereby improving the appearance of the leaves.

[0011] S4, Loading: Load tobacco leaves by category and layer, maintaining the same quality in the same layers. Physiologically mature tobacco leaves are loaded in the low-temperature layer of the intensive flue-curing barn, fully mature tobacco leaves are loaded in the high-temperature layer of the intensive flue-curing barn, and mature tobacco leaves are loaded in the remaining positions. The loading density is reduced by 10% to 15% compared to conventional loading. This categorized and layered loading improves the uniformity and synchronization of tobacco leaf quality. Reducing the loading density improves ventilation and moisture removal efficiency in the intensive flue-curing barn, easing the difficulty of coloring the tobacco leaves, reducing ash buildup on the leaves, and improving the appearance of the tobacco leaves.

[0012] S5, baking, includes the yellowing stage, color-fixing stage, and dry-stem stage. During the yellowing stage, a baking technique using high temperature for primary yellowing, early dehumidification in the late yellowing stage, and a gradual reduction in wet-bulb temperature is used; the yellowing degree of the tobacco leaves is reduced during the fire change; during the color-fixing stage, a low-temperature, low-humidity, slow-heating baking technique for color fixation is used, with the wet-bulb temperature gradually increased in the early color-fixing stage; and during the dry-stem stage, a rapid dry-stem baking technique is used.

[0013] The baking method during the yellowing period is as follows: after ignition, the dry-bulb temperature is raised to 33°C and the wet-bulb temperature is 32°C at a heating rate of 1°C / h, and the temperature is kept constant for 2-3 hours to start the yellowing of the tobacco leaves; thereafter, the dry-bulb temperature is raised to 36°C and the wet-bulb temperature is 35°C at a heating rate of 1°C / h, and the temperature is kept constant for 3-5 hours, the tobacco leaves turn 10% to 20% yellow, and the leaves become slightly soft; thereafter, the dry-bulb temperature is raised to 36°C and the wet-bulb temperature is 35°C at a heating rate of 1°C / h, and the temperature is kept constant for 3-5 hours, the tobacco leaves turn 10% to 20% yellow, and the leaves become slightly soft; thereafter, the dry-bulb temperature is raised to 38℃, wet-bulb temperature 35-36℃, bake at steady temperature for 10-15h, tobacco leaves turn 30%-40% yellow and become soft; then, increase the temperature to 40-41℃ at a rate of 1℃ / 2h, wet-bulb temperature 35℃, bake at steady temperature for 4-6h; then, reduce the wet-bulb temperature by 0.5℃ every 6-10h, gradually reduce the wet-bulb temperature to 33.5℃, bake at steady temperature until tobacco leaves turn 70%-80% yellow and become fully soft and withered.

[0014] The baking method during the color fixing period is as follows: the dry-bulb temperature is raised to 43-44° C. and the wet-bulb temperature is 33.5° C. at a heating rate of 1° C. / 3 hours, and the temperature is kept constant for 3-5 hours; thereafter, the wet-bulb temperature is raised by 0.5° C. every 6-10 hours of baking, and the wet-bulb temperature is gradually raised to 35.0° C., and the temperature is kept constant for baking until the tobacco leaves on the whole kang are yellow and have blue veins, have lost 50%-60% of their water content, and are more than 1 / 2 dry; thereafter, the dry-bulb temperature is raised to 46° C. and the wet-bulb temperature is 35-36° C. at a heating rate of 1° C. / 3 hours, and the temperature is kept constant for 15-20 hours, until the main veins of the tobacco leaves on the whole kang are completely yellow and more than one-third dry, and the leaves are basically completely dry;

[0015] The baking method during the dry-core period is as follows: the dry-bulb temperature is raised to 55°C and the wet-bulb temperature is 36-37°C at a heating rate of 1°C / h, and the temperature is kept constant for 3-5 hours until the main ribs of the tobacco leaves on the whole bed are more than half dry. Thereafter, the dry-bulb temperature is raised to 65-67°C and the wet-bulb temperature is 37-38°C at a heating rate of 1°C / h, and the temperature is kept constant until the tobacco leaves on the whole bed are completely dry. It should be noted that the main ribs of the tobacco leaves at 55°C are more than half dry, indicating a high degree of dryness.

[0016] Preferably, in step S1, the foliar nutrient solution is a plant all-purpose nutrient solution, but does not contain nitrogen. The spraying should be done between 4 and 6 pm in rainless weather to coordinate the nutritional balance of the upper tobacco leaves, improve the baking resistance of the tobacco leaves, and prevent the tobacco leaves from turning green again.

[0017] Preferably, the foliar nutrient solution plant all-purpose nutrient solution is a new type of high-efficiency concentrated nutrient regulator specially used for tobacco leaves.

[0018] Preferably, in step S2, 8 to 12 days after the middle tobacco leaves are mature and harvested, the upper 4 to 6 fresh tobacco leaves are harvested at one time.

[0019] The technical principle of the present invention is: due to the malnutrition of the soil in the white eel mud tobacco field, the upper leaves are easy to bake but not resistant to baking, that is, the baking resistance is poor, so the baking resistance of the tobacco leaves is improved by spraying nutrient solution on the leaves before harvesting; the maturity of the tobacco leaves is appropriately reduced during harvesting, the consumption of substances contained in the tobacco leaves in the field is reduced, and the baking resistance of the tobacco leaves is improved; the amount of tobacco leaves is appropriately reduced during weaving, and the density of tobacco leaves is reduced when loading on the kang to improve the ventilation and dehumidification efficiency of the dense baking room, reduce the difficulty of tobacco leaf color setting, and reduce the dust on the tobacco leaves; reduce the yellowing degree of the tobacco leaves when changing the fire; during baking, the baking technology of high temperature main yellowing, early dehumidification in the late yellowing period and gradual reduction of wet-bulb temperature is adopted in the yellowing period, the low temperature and low humidity slow heating color fixing baking technology is adopted in the color fixing period, the wet-bulb temperature is gradually increased in the early stage of color fixing, and the fast dry-stem baking technology is adopted in the dry-stem period to reduce the difficulty of color fixing of the upper tobacco leaves, reduce the dust on the upper tobacco leaves, and improve the appearance quality and internal quality of the tobacco leaves after baking.

[0020] Specifically, high temperatures during the yellowing phase can reduce the consumption of nutrients in tobacco leaves during prolonged, low-temperature curing, thereby improving their curing resistance. Early dehumidification and gradually lowering the wet-bulb temperature in the late yellowing phase reduce moisture content, inhibit enzyme activity and browning, prevent ash buildup and browning, and improve the appearance of the cured leaves. Reducing the degree of yellowing during the heat transition reduces nutrient consumption during the yellowing phase and improves their curing resistance. Low-temperature, low-humidity, slow-heat curing during the color-fixing phase reduces moisture content, increases dryness, inhibits enzyme activity and browning, prevents ash buildup and browning, and improves the appearance of the cured leaves. Gradually increasing the wet-bulb temperature during the early color-fixing phase, while maintaining color stability, promotes the conversion of tobacco leaves, deepens color, increases the proportion of orange-yellow tobacco leaves, and improves the balance of chemical composition. Rapid curing during the dry-core phase reduces the loss of aroma compounds caused by prolonged, high-temperature curing, thereby improving the sensory quality of the leaves.

[0021] The beneficial effects of the present invention are as follows: in order to solve the problems of difficulty in fixing color and easy dust accumulation in the existing tobacco leaves in the upper part of the white eel mud tobacco field during baking, the present invention first improves the quality of tobacco leaves and enhances the baking resistance of tobacco leaves by spraying nutrient solution on the leaves before harvesting; secondly, by appropriately reducing the maturity of tobacco leaves during harvesting and reducing the consumption of substances contained in tobacco leaves in the field, the baking resistance of tobacco leaves is improved; thirdly, by appropriately reducing the amount of tobacco leaves when weaving and reducing the density of tobacco leaves when loading on the kang to improve the ventilation and dehumidification efficiency of the dense baking room, the difficulty in fixing color of tobacco leaves is reduced and the dust accumulation of tobacco leaves is reduced; finally, by adopting the baking technology of high temperature for main yellowing, early dehumidification in the late yellowing stage and gradual reduction of wet-bulb temperature in the yellowing stage, the yellowing degree of tobacco leaves is reduced when switching to fire, the low temperature and low humidity slow heating and color fixing baking technology is adopted in the color fixing stage, the wet-bulb temperature is gradually increased in the early stage of color fixing, and the fast dry-stem baking technology is adopted in the dry-stem stage, so as to reduce the difficulty in fixing color of the upper tobacco leaves, reduce the dust accumulation of the upper tobacco leaves, and improve the appearance quality and intrinsic quality of the tobacco leaves after baking. The present invention overcomes the shortcomings of existing conventional cultivation and production management techniques and curing processes by combining foliar nutrient solution spraying, scientific harvesting, rational tobacco packaging, and precise curing measures. It can improve the curing resistance of the upper tobacco leaves grown in the white eel mud field, reduce the curing difficulty, reduce the amount of ash on the upper tobacco leaves after curing, and improve the quality of the upper tobacco leaves after curing. The present invention has the following advantages: 1. It helps improve the curing resistance of the upper tobacco leaves; 2. It helps reduce the proportion of ash on the tobacco leaves after curing; and 3. It helps improve the appearance and internal quality of the tobacco leaves after curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a local conventional baking technology;

[0023] Figure 2 This is a picture of the tobacco leaves in the upper part of the Baichenni tobacco field after being cured in the conventional curing barn;

[0024] Figure 3 This is a picture of the tobacco leaves from the upper part of the Baichenni tobacco field after conventional baking on a single pole;

[0025] Figure 4 This is a picture of the tobacco leaves in the upper part of the Baichenni tobacco field after being cured in the new technology curing barn;

[0026] Figure 5 This is a picture of the tobacco leaves baked on single poles using the new baking technology in the upper part of the Bailianni tobacco field. DETAILED DESCRIPTION

[0027] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0028] 1. Foliar nutrient solution spraying test

[0029] The experiment was conducted in tobacco-growing areas such as Yinjiang County, Tongren City, Guizhou Province from 2022 to 2023. The flue-cured tobacco variety tested was Yunyan 87 from Baichenni Yantian, and leaves from the upper third position were used as test material. A comparative experiment was conducted using the method of the present invention as a control, using local conventional cultivation and production management techniques as a control.

[0030] Treatment group: Two days before harvest, spray the leaves with a foliar nutrient solution containing all-purpose plant nutrient solution, but not nitrogen, between 4 and 6 p.m. on rainless days. Specifically, it is a new type of high-efficiency concentrated nutrient regulator specially designed for tobacco leaves.

[0031] The method of the present invention is evaluated and analyzed from the perspective of the curing characteristics of fresh tobacco leaves from the upper part of the Bailianni tobacco field. The measured indicators are polyphenol oxidase (PPO) and the time it takes for tobacco leaves to turn yellow and brown in the dark box.

[0032] Table 1 Effects of spraying nutrient solution on the curing characteristics of upper fresh tobacco leaves

[0033]

[0034] Note: Different lowercase letters indicate significant differences at the 5% level, with 3 biological replicates.

[0035] As shown in Table 1, after spraying the nitrogen-free plant nutrient solution on the upper fresh tobacco leaves in the Baichenni tobacco field, the PPO activity of the leaves was significantly reduced. The time it took for the leaves to turn completely yellow in the darkroom was not significantly different from that in the control, but the time it took for the leaves to turn completely brown in the darkroom was significantly longer than that in the control. This indicates that foliar nutrient solution spraying had no significant effect on the flue-curing ability of the upper tobacco leaves, but significantly improved the flue-curing resistance of the upper fresh tobacco leaves.

[0036] 2. Baking comparison test

[0037] The experiment was conducted in the Baichenni tobacco fields in Yinjiang County, Tongren City, Guizhou Province, from 2022 to 2023. The flue-cured tobacco variety Yunyan 87 was used, and the upper 4 to 6 leaves were used as test material. The comparative experiment was conducted using the method of the present invention as a control, using local conventional cultivation and production management techniques as a control.

[0038] The method of the present invention is as follows:

[0039] S1, spraying: at 4 pm on rainless days 2 days before harvest, spray the upper tobacco leaves of the white eel mud tobacco field with foliar plant all-purpose nutrient solution (a new type of high-efficiency concentrated nutrient regulator specially designed for tobacco leaves), but excluding nitrogen.

[0040] S2, harvesting: 10 days after the middle tobacco leaves are mature and harvested, 4 to 6 upper fresh tobacco leaves are physiologically mature and harvested at one time. The harvest maturity is 20% lower than the normal level. The leaves are mainly yellow, with a yellow area of ​​60% to 70% on the leaf surface. The main veins are white, more than half of the branch veins are white, and most of the hairs fall off.

[0041] S3, tobacco weaving: the tobacco leaves are divided into three categories according to their maturity: physiological maturity, mature and fully mature, and then weaved into poles. Each pole is made of 140 to 150 tobacco leaves.

[0042] S4, Loading: Load tobacco in layers according to classification and quality. Physiologically mature tobacco leaves are loaded in the low-temperature layer of the intensive flue-curing barn, fully mature tobacco leaves are loaded in the high-temperature layer of the intensive flue-curing barn, and mature tobacco leaves are loaded in the remaining positions. The loading density is reduced by 12% compared with the conventional method.

[0043] S5, baking, including yellowing period, color setting period and tendon drying period;

[0044] Wherein, the baking method in the yellowing period is: after ignition, the dry-bulb temperature is raised to 33°C and the wet-bulb temperature is 32°C at a heating rate of 1°C / h, and the tobacco leaves are baked at a steady temperature for 3 hours to start yellowing; thereafter, the dry-bulb temperature is raised to 36°C and the wet-bulb temperature is 35°C at a heating rate of 1°C / h, and the tobacco leaves are baked at a steady temperature for 4 hours, the tobacco leaves turn 10% to 20% yellow, and the leaves become slightly soft; thereafter, the dry-bulb temperature is raised to 38°C and the wet-bulb temperature is 35-36°C at a heating rate of 1°C / h, and the tobacco leaves are baked at a steady temperature for 12 hours, the tobacco leaves turn 30% to 40% yellow, and the leaves become soft; thereafter, the dry-bulb temperature is raised to 40-41°C and the wet-bulb temperature is 35°C at a heating rate of 1°C / 2h, and the tobacco leaves are baked at a steady temperature for 5 hours; thereafter, the wet-bulb temperature is reduced by 0.5°C every 8 hours of baking, and the wet-bulb temperature is gradually reduced to 33.5°C, and the tobacco leaves are baked at a steady temperature until they turn 70% to 80% yellow and are fully softened and withered;

[0045] The baking method during the color fixing period is as follows: the dry-bulb temperature is raised to 44° C. and the wet-bulb temperature is 33.5° C. at a heating rate of 1° C. / 3 hours, and the temperature is kept constant for 5 hours; thereafter, the wet-bulb temperature is raised by 0.5° C. every 8 hours, and the wet-bulb temperature is gradually raised to 35.0° C., and the temperature is kept constant for baking until the tobacco leaves on the whole kang are yellow with green veins, 50% to 60% of water is lost, and more than half of the leaves are dried; thereafter, the dry-bulb temperature is raised to 46° C. and the wet-bulb temperature is 35° C. at a heating rate of 1° C. / 3 hours, and the temperature is kept constant for 18 hours, until the main veins of the tobacco leaves on the whole kang are completely yellow and more than one-third are dried, and the leaves are basically completely dry;

[0046] The baking method during the dry rib period is: heating the leaves at a rate of 1°C / h to raise the dry-bulb temperature to 55°C and the wet-bulb temperature to 36.5°C, and baking at a steady temperature for 5 hours until the main ribs of the tobacco leaves on the whole bed are more than half dry; thereafter, heating the leaves at a rate of 1°C / h to raise the dry-bulb temperature to 65°C and the wet-bulb temperature to 38°C, and baking at a steady temperature until the tobacco leaves on the whole bed are completely dry.

[0047] Local conventional baking techniques such as Figure 1 As shown, no new high-efficiency concentrated nutrient regulator specifically for tobacco leaves was sprayed before harvesting. The fresh tobacco leaves were harvested according to normal maturity, and the tobacco weaving and bed loading were carried out according to conventional requirements.

[0048] The effects of the method of the present invention (new baking process) and the local conventional baking technology (control) on the appearance quality, grade structure, chemical composition and sensory quality of the upper tobacco leaves after baking are described below.

[0049] Table 2 Effects of different treatments on the appearance quality of the upper part of tobacco leaves after flue-curing

[0050]

[0051]

[0052] Table 3 Effects of different treatments on the grade structure of flue-cured tobacco leaves

[0053]

[0054] Table 4 Effects of different treatments on the chemical composition content of flue-cured tobacco leaves

[0055]

[0056] Note: The sugar-alkali ratio is the ratio of reducing sugar to nicotine, generally between 6 and 10, and the closer to 10 the better; the two-sugar ratio is the ratio of reducing sugar to total sugar, generally between 0 and 1, and the closer to 1 the better.

[0057] Table 5 Effects of different treatments on sensory quality of flue-cured tobacco leaves

[0058]

[0059] Note: The maximum score for each individual indicator is 9 points. The greater the concentration of momentum, the higher the score. For other indicators, the better the quality characteristics, the higher the score.

[0060] As shown in Tables 2-5, compared with conventional production methods, the present method produces tobacco leaves with better appearance quality after flue-curing, a higher proportion of orange and upper-medium tobacco, a lower proportion of ash-containing tobacco, a more balanced chemical composition, and relatively better sensory quality. Therefore, the present method is beneficial for reducing the proportion of ash-containing tobacco leaves after flue-curing and improving both the appearance and internal quality of flue-cured tobacco leaves.

[0061] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for baking tobacco leaves in the upper part of a white eel mud tobacco field, characterized in that: include: S1, spraying: spraying foliar nutrient solution on the upper tobacco leaves in the white eel mud tobacco field 1-2 days before harvest, wherein the foliar nutrient solution does not contain nitrogen; S2, harvesting: The upper fresh tobacco leaves are harvested when they are physiologically mature. The harvest maturity is 10% to 30% lower than normal. The leaves are mainly yellow, with 50% to 70% of the leaf surface yellow. The main veins are white, more than half of the side veins are white, and most of the hairs have fallen off. S3, tobacco weaving: the tobacco leaves are divided into three categories according to their maturity: physiological maturity, mature and fully mature, and then weaved into poles. Each pole contains 130 to 160 tobacco leaves. S4, Loading: Load tobacco in layers according to classification and quality. Physiologically mature tobacco leaves are loaded in the low-temperature layer of the intensive flue-curing barn, fully mature tobacco leaves are loaded in the high-temperature layer of the intensive flue-curing barn, and mature tobacco leaves are loaded in the remaining positions. The loading density is reduced by 10-15% compared with the conventional method. S5, baking, including yellowing period, color setting period and tendon drying period; The baking method during the yellowing period is as follows: after ignition, the dry-bulb temperature is raised to 33°C and the wet-bulb temperature is 32°C at a heating rate of 1°C / h, and the temperature is kept constant for 2-3 hours to start the yellowing of the tobacco leaves; thereafter, the dry-bulb temperature is raised to 36°C and the wet-bulb temperature is 35°C at a heating rate of 1°C / h, and the temperature is kept constant for 3-5 hours, the tobacco leaves turn 10% to 20% yellow, and the leaves become slightly soft ... To 38℃, wet-bulb temperature 35~36℃, and bake at a steady temperature for 10~15h, until the tobacco leaves turn 30%~40% yellow and become soft; then, increase the temperature at a rate of 1℃ / 2h to 40~41℃, wet-bulb temperature 35℃, and bake at a steady temperature for 4~6h; then, reduce the wet-bulb temperature by 0.5℃ every 6~10h, gradually reduce the wet-bulb temperature to 33.5℃, and bake at a steady temperature until the tobacco leaves turn 70%~80% yellow and fully become soft and withered; The baking method during the color fixing period is as follows: the dry-bulb temperature is raised to 43-44°C and the wet-bulb temperature is 33.5°C at a heating rate of 1°C / 3h, and the temperature is kept constant for 3-5h; thereafter, the wet-bulb temperature is raised by 0.5°C every 6-10h, and the temperature is gradually raised to 35.0°C, and the temperature is kept constant for baking until the tobacco leaves on the whole kang have yellow leaves and blue veins, lose 50%-60% of their water content, and are more than 1 / 2 dry; thereafter, the dry-bulb temperature is raised to 46°C and the wet-bulb temperature is 35-36°C at a heating rate of 1°C / 3h, and the temperature is kept constant for 15-20h, until the main veins of the tobacco leaves on the whole kang are completely yellow and more than one-third dry, and the leaves are basically completely dry; The baking method during the dry rib period is: heating the leaves at a rate of 1°C / h to raise the dry-bulb temperature to 55°C and the wet-bulb temperature to 36~37°C, and baking at a steady temperature for 3~5 hours until the main ribs of the tobacco leaves on the whole bed are more than half dry; thereafter, heating the leaves at a rate of 1°C / h to raise the dry-bulb temperature to 65~67°C and the wet-bulb temperature to 37~38°C, and baking at a steady temperature until the tobacco leaves on the whole bed are completely dry.

2. The method for baking tobacco leaves in the upper part of the white eel mud tobacco field according to claim 1, characterized in that: In step S1, the spraying time is selected between 4 and 6 p.m. when there is no rain.

3. The method for baking tobacco leaves in the upper part of the white eel mud tobacco field according to claim 1, characterized in that: In step S2, 8 to 12 days after the middle tobacco leaves are mature and harvested, the upper 4 to 6 fresh tobacco leaves are harvested at one time.

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