Harvesting and baking method for flue-cured tobacco hybrid YY021

Abstract

The invention discloses a flue-cured tobacco hybrid YY021 harvesting and baking method, and belongs to the technical field of flue-cured tobacco harvesting and curing. The method comprises the following steps: (1) harvesting YY021 tobacco leaves: (1) harvesting lower tobacco leaves at proper maturity; (2) delayed harvesting of middle tobacco leaves; (3) delayed harvesting of upper tobacco leaves; (2) baking the YY021 tobacco leaves: dividing the tobacco leaves into three types, namely non-overnutrition lower tobacco leaves, non-overnutrition middle tobacco leaves, non-overnutrition upper tobacco leaves and overnutrition tobacco leaves; a traditional baking process is not suitable for YY021 baking, an accurate harvesting and baking process is formulated according to the characteristics of the YY021 variety, the baked tobacco leaves are few in mixed color, and the ratio of baking green leaves to baking grains is low.

Description

Technical Field

[0001] The invention relates to the technical field of flue-cured tobacco harvesting and curing, and more particularly to a method for harvesting and curing a flue-cured tobacco hybrid YY021. Background Art

[0002] YY021 is a flue-cured tobacco hybrid with a well-developed root system, drought resistance, and strong growth potential. The aroma of the tobacco leaves after curing is good and sufficient, but its harvesting method and curing process are quite different from those of the main varieties such as Zhongyan 100 and Yunyan 87. The curing effect of YY021 tobacco leaves according to traditional methods is not good, with gray or green curing, poor color, and cannot fully demonstrate the quality style of YY021 tobacco leaves. The maturity and curing characteristics of YY021 tobacco leaves are different from those of the main varieties, mainly reflected in the strong growth of tobacco plants in the later stage, high water content of tobacco leaves, high bound water content of tobacco leaves, and difficulty in drainage of tobacco leaves during the yellowing period, especially in the middle and upper leaves.

[0003] Therefore, how to develop a method for harvesting and baking the flue-cured tobacco hybrid YY021 that solves the problem of YY021 harvesting and baking and improves the quality of tobacco leaves is an issue that technicians in this field urgently need to solve. Summary of the invention

[0004] In view of this, the present invention provides a method for harvesting and baking a flue-cured tobacco hybrid YY021.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for harvesting and baking a flue-cured tobacco hybrid YY021, comprising the following steps:

[0007] (I) YY021 tobacco leaf harvesting includes the following steps:

[0008] (1) The lower tobacco leaves are harvested when they are 55-60 days old, slightly yellow in color, with the hairs partially falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves naturally bending, and the SPAD value of the leaves being 20-24.

[0009] (2) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: the leaves are 70-75 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 18-22, then the middle tobacco leaves are harvested;

[0010] (3) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 10-15 days, and the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: the leaves are 85-90 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tips droop naturally, there is oil on the leaf surface, and the leaf SPAD value is 16-20, then the upper tobacco leaves are harvested;

[0011] (II) YY021 tobacco leaf baking:

[0012] The tobacco leaves were divided into three categories, namely, non-nutritional lower tobacco leaves, non-nutritional middle and upper tobacco leaves, and nutritious tobacco leaves.

[0013] The non-nutrition excess lower tobacco leaf baking comprises the following steps:

[0014] 1) Yellowing stage

[0015] After loading the non-nutritional excess lower tobacco leaves into the curing room, close the curing room door and start curing. At the same time, start the high-speed gear of the circulating fan, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, the fan speed is 960 rpm, the wet bulb temperature is 37°C, and the temperature is kept stable for 1 hour, and the yellowing degree of the tobacco leaves in the high-temperature shed layer reaches 80-90%, that is, the yellow leaves have blue veins, the leaves are collapsed and soft, and more than 1 / 3 of the main veins are soft and collapsed; more than 80% of the tobacco leaves in the bottom shed are yellowed to 70-80%, and the leaves are withered and soft and not easy to break;

[0016] Then the dry bulb temperature is raised to 39℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃, and the temperature is kept stable until more than 80% of the tobacco leaves in the middle and lower sheds turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse;

[0017] Then the dry bulb temperature is raised to 41℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept stable until more than 80% of the tobacco leaves in the middle and upper sheds turn yellow, the veins of the yellow leaves are slightly green, and 2 / 3 of the main veins are soft but not broken. The tobacco leaves in the lower shed turn yellow to 80%-90%, and 1 / 2 of the main veins are soft. The above yellowing and drying standards are met to complete the yellowing stage task;

[0018] 2) Color Fixation Stage

[0019] Adjust the circulating fan to high speed, fan speed 1440 rpm, dry bulb temperature rises to 42℃ at a rate of 0.25℃ / h, wet bulb temperature 35-36℃, keep the temperature stable for 12-24 hours, until the main veins of the tobacco leaves on the ceiling are completely yellow and the rolls are soft and curled with hooks and edges. The principle of yellowing tobacco leaves is: yellow leaves do not turn brown, green leaves can turn yellow, and yellow tobacco is equal to green tobacco;

[0020] Then the dry bulb temperature is raised to 45-46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 36-38℃. The temperature is kept stable for 12-24h, until the tobacco leaves on the upper shed in the flue-curing room have completed the yellowing and shrinking of the leaves, i.e., the yellow leaves and yellow tendons are rolled into small rolls.

[0021] Then the dry bulb temperature is raised to 48-52℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37-39℃, and the temperature is kept stable for 8-12h, until the tobacco leaves in the lower shed of the curing room have completed yellowing and shrinking, i.e. yellow leaves and yellow tendons small rolls;

[0022] Then the dry bulb temperature is raised to 54℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37-39℃, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept constant for 8 hours; the tobacco leaves on the upper shed in the curing room turn yellow to 100%, and dry to the point that only the main veins are not dry, that is, yellow leaves and yellow tendons are large rolls; 70% of the tobacco leaves on the lower shed meet the above standards, and the color fixing stage task is completed;

[0023] 3) Drying stage

[0024] The dry bulb temperature is raised to 60℃ at a rate of 1℃ / h, the wet bulb temperature is 39-41℃, and the temperature is kept stable for 4-6 hours; so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0025] Then the dry bulb temperature is raised to 67-68℃ at a rate of 1℃ / h, and the wet bulb temperature is 41-42℃. The temperature is kept stable for 12-24h, until the main veins of the tobacco leaves in the flue-curing room are completely dry, that is, the tobacco leaves are completely dry without fleshy tendons, completing the task of the tendon drying stage;

[0026] The baking of the non-nutritionally excessive middle and upper tobacco leaves comprises the following steps:

[0027] ① Pre-yellowing stage

[0028] After the non-nutritional excess middle and upper tobacco leaves are baked and loaded into the curing room, the curing room door is closed to pre-yellow the tobacco leaves by relying on the natural temperature in the curing room. The pre-yellowing takes 18 hours, and the tip of the leaves turns yellow. Then, baking begins. At the same time, the high-speed gear of the circulating fan is enabled, and the fan speed is 1440 rpm. When the dry-bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, and the fan speed is 960 rpm, the wet-bulb temperature is 37°C, and the temperature is kept stable for 12-24 hours, until the yellowing of the leaves in the high-temperature shed layer reaches 80% to 90%, and the leaves collapse and become soft;

[0029] Then the dry bulb temperature is raised to 39-40℃ at a rate of 0.3℃ / h, and the wet bulb temperature is raised to 39℃, reaching 80% to 90% yellowing of tobacco leaves in the middle shed, with leaves withering and softening, more than 1 / 3 of the main veins softening and collapsing, leaves are soft and not easy to break, and the appearance shows green veins and yellow flakes;

[0030] Then the dry bulb temperature is raised to 42℃ at a rate of 0.3℃ / h. During the dry bulb temperature rise period, the wet bulb temperature is maintained at 38-39℃. Then the dry bulb temperature is kept stable for 12-24h. During the dry bulb temperature stability period, the wet bulb temperature is lowered to 38℃, and more than 80% of the tobacco leaves in the bottom shed turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse.

[0031] ② Yellowing-color fixation transition stage

[0032] Adjust the circulating fan to high speed, fan speed 1440 rpm, dry bulb temperature rises to 44℃ at a rate of 0.3℃ / h, wet bulb temperature 36℃, keep the temperature stable for 8-18h, reach 80% or more of the tobacco leaves in the bottom shed turn yellow to 90%, yellow leaves have slightly green veins, 2 / 3 of the main veins become soft, broken but not broken branch veins become soft, and the leaves fully collapse;

[0033] ③Color Fixation Stage

[0034] The dry bulb temperature rises to 46℃ at a rate of 0.3℃ / h, the wet bulb temperature is 35.5℃, and the temperature is kept stable for 6-12h, until the tobacco leaves reach the ceiling, the main veins are completely yellow, the soft rolls are completely white, and the edges are curled;

[0035] Then the dry bulb temperature is raised to 47-48℃ at a rate of 0.2℃ / h, and the wet bulb temperature is 36.5℃. The temperature is kept stable for 6-12h, until the tobacco leaves in the middle layer of the flue-curing room are fully yellowed and softened, and the yellow leaves and yellow tendons are rolled into small rolls;

[0036] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37-38℃, and the temperature is kept stable for 6-8h, until the yellow leaves and yellow tendons of the tobacco leaves in the bottom shed are rolled into small rolls;

[0037] Then the dry bulb temperature is raised to 54°C at a rate of 1.5°C / h, the wet bulb temperature is 38-39°C, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours to achieve full-heated tobacco leaf large rolls;

[0038] ④ Drying stage

[0039] The dry bulb temperature is raised to 60℃ at a rate of 0.75℃ / h, the wet bulb temperature is 39-41℃, and the temperature is kept stable for 4-6 hours; so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0040] Then the dry bulb temperature is raised to 67-68℃ at a rate of 2℃ / h, and the wet bulb temperature is 41-42℃. The temperature is kept stable for 12-24h, until the main veins of the tobacco leaves in the flue-curing room are completely dry, that is, the tobacco leaves are completely dry without fleshy tendons, completing the task of the tendon drying stage;

[0041] The baking of the nutritionally excess tobacco leaves comprises the following steps:

[0042] (A) Yellowing due to low temperature and humidity control

[0043] After loading the tobacco leaves with excess nutrition into the curing room, close the curing room door and ignite the fire in time, and at the same time enable the high-speed gear of the circulating fan, with the fan speed of 1440 rpm;

[0044] Then the dry bulb temperature is raised to 38-40℃ at a rate of 1℃ / h, and the wet bulb temperature is 37-38℃. The circulating fan is adjusted to low speed, with a fan speed of 960 rpm, and the temperature is kept stable for 8 hours.

[0045] Then the dry bulb temperature is raised to 39-41°C at a rate of 1°C / h, and the wet bulb temperature is 36-38°C. The temperature is kept constant for 24-48 hours until the tobacco leaves turn 70% to 80% yellow.

[0046] (B) Stable temperature and moisture removal withering

[0047] Then adjust the circulating fan to high speed, with the fan speed of 1440 rpm, and then increase the dry bulb temperature to 42-44℃ at a rate of 0.5℃ / h, and the wet bulb temperature to 33-35℃, and keep the temperature stable for 12-24h, until the ceiling tobacco ribs and leaf bases are completely 90% to 10% yellow, and the tobacco leaves wither and collapse until the hook tip curls;

[0048] Then the dry bulb temperature is raised to 45-48℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 33-35℃. The temperature is kept stable for 10 hours until the tobacco leaves in the lower shed turn completely yellow and curl at the edges, and the tobacco leaves in the upper shed reach small rolls.

[0049] (C) Dehydrated leaves

[0050] Then the dry bulb temperature is raised to 48-50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 33-35℃, and the temperature is kept stable for 6-12h until the tobacco leaves in the lower shed reach the small rolls and the tobacco leaves in the upper shed reach the large rolls;

[0051] Then the dry bulb temperature is raised to 53-54℃ at a rate of 1℃ / h, and the wet bulb temperature is 37-39℃. The circulating fan is adjusted to low speed, and the fan speed is 960 rpm. The temperature is kept stable for more than 12 hours, until the tobacco leaves in the flue-curing room are completely dry and only the main tendons are not dry before reaching the large reel.

[0052] (D) Dry muscle period

[0053] Then the dry bulb temperature is raised to 60-62℃ at a rate of 1℃ / h, the wet bulb temperature is 41-42℃, and the temperature is kept stable for 10 hours to ensure that the tobacco leaves in the low temperature area reach the large roll;

[0054] Then the dry bulb temperature is raised to 67-68°C at a rate of 1°C / h, the wet bulb temperature is 41-43°C, and the temperature is kept stable for 16 hours to completely dry the tobacco leaves.

[0055] Beneficial effects of the present invention: Traditional baking technology is not suitable for YY021 baking. The present invention formulates a precise harvesting and baking technology based on the characteristics of the YY021 variety. After baking, the tobacco leaves have less variegated colors and the proportion of baked green and baked dregs is low. DETAILED DESCRIPTION

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0057] Example 1

[0058] The method for harvesting and baking the non-nutrition surplus lower tobacco leaves of the flue-cured tobacco hybrid YY021 comprises the following steps:

[0059] (I) YY021 tobacco leaf harvesting includes the following steps:

[0060] (1) The lower tobacco leaves are harvested when they are 60 days old, slightly yellow in color, with the hairs partially falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves naturally bending, and the SPAD value of the leaves is 20.

[0061] (II) YY021 tobacco leaf baking:

[0062] 1) Yellowing stage

[0063] After loading the non-nutritional excess lower tobacco leaves into the curing room, close the curing room door and start curing. At the same time, start the high-speed gear of the circulating fan, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, the fan speed is 960 rpm, the wet bulb temperature is 37°C, and the temperature is kept stable for 1 hour, and the yellowing degree of the tobacco leaves in the high-temperature shed layer reaches 80-90%, that is, the yellow leaves have blue veins, the leaves are collapsed and soft, and more than 1 / 3 of the main veins are soft and collapsed; more than 80% of the tobacco leaves in the bottom shed are yellowed to 70-80%, and the leaves are withered and soft and not easy to break;

[0064] Then the dry bulb temperature is raised to 39℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 33 hours until more than 80% of the tobacco leaves in the middle and lower sheds turn yellow, with the leaves withering and softening, and more than 1 / 3 of the main veins become soft and collapse.

[0065] Then the dry bulb temperature is raised to 41℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 2 hours until more than 80% of the tobacco leaves in the middle and upper sheds turn yellow to 90%, with the veins of the yellow leaves slightly green, and 2 / 3 of the main veins become soft but not broken. The tobacco leaves in the lower shed turn yellow to 80%-90%, with 1 / 2 of the main veins softened. The above yellowing and drying standards are met to complete the yellowing stage task;

[0066] 2) Color Fixation Stage

[0067] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 42℃ at a rate of 0.25℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 12 hours, until the main veins of the tobacco leaves on the ceiling are completely yellow and the rolls are soft and curled with hooks and tips. The principle of yellowing tobacco leaves is: yellow leaves do not turn brown, green leaves can turn yellow, and yellow tobacco is equal to green tobacco;

[0068] Then the dry bulb temperature is raised to 46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 38℃. The temperature is kept constant for 12 hours until the tobacco leaves on the upper shed in the flue-curing room have completed the yellowing and shrinking of the leaves, i.e., the yellow leaves and yellow tendons are rolled into small rolls.

[0069] Then the dry bulb temperature is raised to 52℃ at a rate of 0.5℃ / h, the wet bulb temperature is 39℃, and the temperature is kept constant for 8h, until the tobacco leaves in the lower shed of the flue-curing room have completed yellowing and shrinking, i.e. yellow leaves and yellow tendons small rolls;

[0070] Then the dry bulb temperature is raised to 54℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 39℃. The circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept constant for 8 hours. The upper shed tobacco leaves in the curing room turn yellow to 100%, and dry to the point that only the main veins are not dry, that is, yellow leaves and yellow tendons are large rolls; 70% of the lower shed tobacco leaves meet the above standards, and the color fixing stage task is completed;

[0071] 3) Drying stage

[0072] The dry bulb temperature is raised to 60℃ at a rate of 1℃ / h, the wet bulb temperature is 41℃, and the temperature is kept constant for 5 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0073] Then the dry bulb temperature is raised to 68°C at a rate of 1°C / h, the wet bulb temperature is 42°C, and the temperature is kept stable for 12 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0074] Example 2

[0075] The method for harvesting and baking the non-nutrition surplus lower tobacco leaves of the flue-cured tobacco hybrid YY021 comprises the following steps:

[0076] (I) YY021 tobacco leaf harvesting includes the following steps:

[0077] (1) The lower tobacco leaves are harvested when they are 58 days old, slightly yellow in color, with some hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves are naturally bent, and the SPAD value of the leaves is 22.

[0078] (II) YY021 tobacco leaf baking:

[0079] 1) Yellowing stage

[0080] After loading the non-nutritional excess lower tobacco leaves into the curing room, close the curing room door and start curing. At the same time, start the high-speed gear of the circulating fan, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, the fan speed is 960 rpm, the wet bulb temperature is 37°C, and the temperature is kept stable for 1 hour, and the yellowing degree of the tobacco leaves in the high-temperature shed layer reaches 80-90%, that is, the yellow leaves have blue veins, the leaves are collapsed and soft, and more than 1 / 3 of the main veins are soft and collapsed; more than 80% of the tobacco leaves in the bottom shed are yellowed to 70-80%, and the leaves are withered and soft and not easy to break;

[0081] Then the dry bulb temperature is raised to 39℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 33 hours until more than 80% of the tobacco leaves in the middle and lower sheds turn yellow, with the leaves withering and softening, and more than 1 / 3 of the main veins become soft and collapse.

[0082] Then the dry bulb temperature is raised to 41℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 2 hours until more than 80% of the tobacco leaves in the middle and upper sheds turn yellow to 90%, with the veins of the yellow leaves slightly green, and 2 / 3 of the main veins become soft but not broken. The tobacco leaves in the lower shed turn yellow to 80%-90%, with 1 / 2 of the main veins softened. The above yellowing and drying standards are met to complete the yellowing stage task;

[0083] 2) Color Fixation Stage

[0084] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 42℃ at a rate of 0.25℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 18 hours, until the main veins of the tobacco leaves on the ceiling are completely yellow and the rolls are soft and curled with hooks and tips. The principle of yellowing tobacco leaves is: yellow leaves do not turn brown, green leaves can turn yellow, and yellow tobacco is equal to green tobacco;

[0085] Then the dry bulb temperature is raised to 46℃ at a rate of 0.5℃ / h, the wet bulb temperature is 38℃, and the temperature is kept constant for 18h, until the tobacco leaves in the upper shed in the flue-curing room have completed the yellowing and shrinking of the leaves, i.e. the yellow leaves and yellow tendons small rolls;

[0086] Then the dry bulb temperature is raised to 52℃ at a rate of 0.5℃ / h, the wet bulb temperature is 39℃, and the temperature is kept constant for 8h, until the tobacco leaves in the lower shed of the flue-curing room have completed yellowing and shrinking, i.e. yellow leaves and yellow tendons small rolls;

[0087] Then the dry bulb temperature is raised to 54℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 39℃. The circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours. The upper shed tobacco leaves in the curing room turn yellow to 100%, and dry to the point that only the main veins are not dry, that is, yellow leaves and yellow tendons are large rolls; 70% of the lower shed tobacco leaves meet the above standards, and the color fixing stage task is completed;

[0088] 3) Drying stage

[0089] The dry bulb temperature is raised to 60℃ at a rate of 1℃ / h, the wet bulb temperature is 41℃, and the temperature is kept constant for 5 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0090] Then the dry bulb temperature is raised to 68°C at a rate of 1°C / h, the wet bulb temperature is 42°C, and the temperature is kept stable for 18 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0091] Example 3

[0092] The method for harvesting and baking the non-nutrition surplus lower tobacco leaves of the flue-cured tobacco hybrid YY021 comprises the following steps:

[0093] (I) YY021 tobacco leaf harvesting includes the following steps:

[0094] (1) The lower tobacco leaves are harvested when they are 55 days old, slightly yellow in color, with some hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves are naturally bent, and the SPAD value of the leaves is 24.

[0095] (II) YY021 tobacco leaf baking:

[0096] 1) Yellowing stage

[0097] After loading the non-nutritional excess lower tobacco leaves into the curing room, close the curing room door and start curing. At the same time, start the high-speed gear of the circulating fan, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, the fan speed is 960 rpm, the wet bulb temperature is 37°C, and the temperature is kept stable for 1 hour, and the yellowing degree of the tobacco leaves in the high-temperature shed layer reaches 80-90%, that is, the yellow leaves have blue veins, the leaves are collapsed and soft, and more than 1 / 3 of the main veins are soft and collapsed; more than 80% of the tobacco leaves in the bottom shed are yellowed to 70-80%, and the leaves are withered and soft and not easy to break;

[0098] Then the dry bulb temperature is raised to 39℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 33 hours until more than 80% of the tobacco leaves in the middle and lower sheds turn yellow, with the leaves withering and softening, and more than 1 / 3 of the main veins become soft and collapse.

[0099] Then the dry bulb temperature is raised to 41℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept at a steady state for 2 hours until more than 80% of the tobacco leaves in the middle and upper sheds turn yellow to 90%, with the veins of the yellow leaves slightly green, and 2 / 3 of the main veins become soft but not broken. The tobacco leaves in the lower shed turn yellow to 80%-90%, with 1 / 2 of the main veins softened. The above yellowing and drying standards are met to complete the yellowing stage task;

[0100] 2) Color Fixation Stage

[0101] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 42℃ at a rate of 0.25℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 24 hours, until the main veins of the tobacco leaves on the ceiling are completely yellow and the rolls are soft and curled with hooks and tips. The principle of yellowing tobacco leaves is: yellow leaves do not turn brown, green leaves can turn yellow, and yellow tobacco is equal to green tobacco;

[0102] Then the dry bulb temperature is raised to 46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 38℃. The temperature is kept constant for 24 hours until the tobacco leaves on the upper shed in the flue-curing room have completed the yellowing and shrinking of the leaves, i.e., the yellow leaves and yellow tendons are rolled into small rolls.

[0103] Then the dry bulb temperature is raised to 52℃ at a rate of 0.5℃ / h, the wet bulb temperature is 39℃, and the temperature is kept constant for 12h, until the tobacco leaves in the lower shed of the curing room have completed yellowing and shrinking, i.e. yellow leaves and yellow tendons small rolls;

[0104] Then the dry bulb temperature is raised to 54℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 39℃. The circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept constant for 8 hours. The upper shed tobacco leaves in the curing room turn yellow to 100%, and dry to the point that only the main veins are not dry, that is, yellow leaves and yellow tendons are large rolls; 70% of the lower shed tobacco leaves meet the above standards, and the color fixing stage task is completed;

[0105] 3) Drying stage

[0106] The dry bulb temperature is raised to 60℃ at a rate of 1℃ / h, the wet bulb temperature is 41℃, and the temperature is kept constant for 5 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0107] Then the dry bulb temperature is raised to 68°C at a rate of 1°C / h, the wet bulb temperature is 42°C, and the temperature is kept stable for 24 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0108] Example 4

[0109] The method for harvesting and baking the middle and upper tobacco leaves of the flue-cured tobacco hybrid variety YY021 without excess nutrition comprises the following steps:

[0110] (I) YY021 tobacco leaf harvesting includes the following steps:

[0111] (1) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: 75 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 18, then the middle tobacco leaves are harvested;

[0112] (2) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: 90 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 16, then the upper tobacco leaves are harvested;

[0113] (II) YY021 tobacco leaf baking:

[0114] ① Pre-yellowing stage

[0115] After the non-nutritional excess middle and upper tobacco leaves are baked and loaded into the curing room, the curing room door is closed to pre-yellow the tobacco leaves by relying on the natural temperature in the curing room. The pre-yellowing takes 18 hours, and the tip of the leaves turns yellow. Then, baking begins. At the same time, the high-speed gear of the circulating fan is enabled, and the fan speed is 1440 rpm. When the dry-bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, and the fan speed is 960 rpm, the wet-bulb temperature is 37°C, and the temperature is kept stable for 12 hours, until the yellow veins of the tobacco leaves in the high-temperature shed layer or the degree of yellowing reaches 80-90%, and the leaves collapse and become soft;

[0116] Then the dry bulb temperature is raised to 40℃ at a rate of 0.3℃ / h, and the wet bulb temperature is raised to 39℃. After the temperature is raised, more than 80% of the tobacco leaves in the middle shed turn yellow to 80-90%, with the leaves withering and softening, more than 1 / 3 of the main veins softening and collapsing, the leaves are soft and not easy to break, and the appearance shows blue veins and yellow flakes;

[0117] Then the dry bulb temperature is raised to 42℃ at a rate of 0.3℃ / h. During the dry bulb temperature rise period, the wet bulb temperature is maintained at 39℃. The dry bulb temperature is kept stable for 12 hours. During the dry bulb temperature stability period, the wet bulb temperature is lowered to 38℃, and more than 80% of the tobacco leaves in the bottom shed turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse.

[0118] ② Yellowing-color fixation transition stage

[0119] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 44℃ at a rate of 0.3℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 8 hours, so that more than 80% of the tobacco leaves in the bottom shed turn yellow to 90%, the veins of the yellow leaves are slightly green, 2 / 3 of the main veins become soft, the broken but unbroken branch veins become soft, and the leaves are fully collapsed;

[0120] ③Color Fixation Stage

[0121] The dry bulb temperature is raised to 46℃ at a rate of 0.3℃ / h, and the wet bulb temperature is 35.5℃. The temperature is kept stable for 6 hours, and the leaves of the tobacco leaves on the roof are completely yellow, the main veins are completely white, and the leaves are soft and curled, with the edges curled.

[0122] Then the dry bulb temperature is raised to 47.5℃ at a rate of 0.2℃ / h, and the wet bulb temperature is 36.5℃. The temperature is kept constant for 6 hours until the tobacco leaves in the middle layer of the flue-curing room are fully yellowed and softened, and the yellow leaves and yellow tendons are rolled into small rolls.

[0123] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37.5℃, and the temperature is kept constant for 8h until the yellow leaves and yellow tendons of the tobacco leaves in the bottom shed are rolled into small rolls;

[0124] Then the dry bulb temperature is raised to 54℃ at a rate of 1.5℃ / h, the wet bulb temperature is 38.5℃, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours to reach the full-heated tobacco leaf roll;

[0125] ④ Drying stage

[0126] The dry bulb temperature is raised to 60℃ at a rate of 0.75℃ / h, the wet bulb temperature is 40℃, and the temperature is kept constant for 6 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0127] Then the dry bulb temperature is raised to 68°C at a rate of 2°C / h, the wet bulb temperature is 41°C, and the temperature is kept stable for 12 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0128] Example 5

[0129] The method for harvesting and baking the middle and upper tobacco leaves of the flue-cured tobacco hybrid variety YY021 without excess nutrition comprises the following steps:

[0130] (I) YY021 tobacco leaf harvesting includes the following steps:

[0131] (1) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: 75 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 20, then the middle tobacco leaves are harvested;

[0132] (2) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 10 days, and then the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: the leaves are 85 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tips droop naturally, there is oil on the leaf surface, and the leaf SPAD value is 18, then the upper tobacco leaves are harvested;

[0133] (II) YY021 tobacco leaf baking:

[0134] ① Pre-yellowing stage

[0135] After the non-nutritional excess middle and upper tobacco leaves are baked and loaded into the curing room, the curing room door is closed to pre-yellow the tobacco leaves by relying on the natural temperature in the curing room. The pre-yellowing takes 18 hours, and the tip of the leaves turns yellow. Then, baking begins. At the same time, the high-speed gear of the circulating fan is enabled, and the fan speed is 1440 rpm. When the dry-bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, and the fan speed is 960 rpm, the wet-bulb temperature is 37°C, and the temperature is kept stable for 18 hours, until the yellow veins of the tobacco leaves in the high-temperature shed layer or the degree of yellowing reaches 80-90%, and the leaves collapse and become soft;

[0136] Then the dry bulb temperature is raised to 40℃ at a rate of 0.3℃ / h, and the wet bulb temperature is raised to 39℃, reaching the point where more than 80% of the tobacco leaves in the middle shed turn yellow to 80-90%, with the leaves withering and becoming soft, more than 1 / 3 of the main veins becoming soft and collapsing, the leaves becoming soft and not easy to break, and the appearance showing green veins and yellow flakes;

[0137] Then the dry bulb temperature is raised to 42℃ at a rate of 0.3℃ / h. During the dry bulb temperature rise period, the wet bulb temperature is maintained at 39℃. The dry bulb temperature is kept stable for 18h. During the dry bulb temperature stability period, the wet bulb temperature is lowered to 38℃, and more than 80% of the tobacco leaves in the bottom shed turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse.

[0138] ② Yellowing-color fixation transition stage

[0139] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 44℃ at a rate of 0.3℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 12 hours, so that more than 80% of the tobacco leaves in the bottom shed turn yellow to 90%, the veins of the yellow leaves are slightly green, 2 / 3 of the main veins become soft, the broken but unbroken branch veins become soft, and the leaves are fully collapsed;

[0140] ③Color Fixation Stage

[0141] The dry bulb temperature is raised to 46℃ at a rate of 0.3℃ / h, and the wet bulb temperature is 35.5℃. The temperature is kept stable for 8 hours, and the leaves of the tobacco leaves on the roof are completely yellow, the main veins are completely white, and the leaves are soft and curled, with the edges curled.

[0142] Then the dry bulb temperature is raised to 47.5℃ at a rate of 0.2℃ / h, and the wet bulb temperature is 36.5℃. The temperature is kept constant for 10 hours until the tobacco leaves in the middle layer of the flue-curing room are fully yellowed and softened, and the yellow leaves and yellow tendons are rolled into small rolls.

[0143] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37.5℃, and the temperature is kept constant for 8h until the yellow leaves and yellow tendons of the tobacco leaves in the bottom shed are rolled into small rolls;

[0144] Then the dry bulb temperature is raised to 54℃ at a rate of 1.5℃ / h, the wet bulb temperature is 38.5℃, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours to reach the full-heated tobacco leaf roll;

[0145] ④ Drying stage

[0146] The dry bulb temperature is raised to 60℃ at a rate of 0.75℃ / h, the wet bulb temperature is 40℃, and the temperature is kept constant for 6 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0147] Then the dry bulb temperature is raised to 68°C at a rate of 2°C / h, the wet bulb temperature is 41°C, and the temperature is kept stable for 18 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0148] Example 6

[0149] The method for harvesting and baking the middle and upper tobacco leaves of the flue-cured tobacco hybrid variety YY021 without excess nutrition comprises the following steps:

[0150] (I) YY021 tobacco leaf harvesting includes the following steps:

[0151] (1) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: 70 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 22, then the middle tobacco leaves are harvested;

[0152] (2) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 10 days, and then the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: the leaves are 85 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tips droop naturally, there is oil on the leaf surface, and the leaf SPAD value is 20, then the upper tobacco leaves are harvested;

[0153] (II) YY021 tobacco leaf baking:

[0154] ① Pre-yellowing stage

[0155] After the non-nutritional excess middle and upper tobacco leaves are baked and loaded into the curing room, the curing room door is closed to pre-yellow the tobacco leaves by relying on the natural temperature in the curing room. The pre-yellowing takes 18 hours, and the tip of the leaves turns yellow. Then, baking begins. At the same time, the circulating fan is enabled at high speed, with a fan speed of 1440 rpm. When the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to low speed and runs continuously, with a fan speed of 960 rpm and a wet bulb temperature of 37°C. The temperature is kept stable for 24 hours, and the yellowing of the leaves in the high-temperature shed layer reaches 80% to 90%, and the leaves collapse and become soft.

[0156] Then the dry bulb temperature is raised to 40℃ at a rate of 0.3℃ / h, and the wet bulb temperature is raised to 39℃, reaching the point where more than 80% of the tobacco leaves in the middle shed turn yellow to 80-90%, with the leaves withering and becoming soft, more than 1 / 3 of the main veins becoming soft and collapsing, the leaves becoming soft and not easy to break, and the appearance showing green veins and yellow flakes;

[0157] Then the dry bulb temperature is raised to 42℃ at a rate of 0.3℃ / h. During the dry bulb temperature rise period, the wet bulb temperature is maintained at 39℃. The dry bulb temperature is kept stable for 24 hours. During the dry bulb temperature stability period, the wet bulb temperature is lowered to 38℃, and more than 80% of the tobacco leaves in the bottom shed turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse.

[0158] ② Yellowing-color fixation transition stage

[0159] The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 44℃ at a rate of 0.3℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 16 hours, so that more than 80% of the tobacco leaves in the bottom shed turn yellow to 90%, the veins of the yellow leaves are slightly green, 2 / 3 of the main veins become soft, the broken but unbroken branch veins become soft, and the leaves are fully collapsed;

[0160] ③Color Fixation Stage

[0161] The dry bulb temperature is raised to 46℃ at a rate of 0.3℃ / h, and the wet bulb temperature is 35.5℃. The temperature is kept stable for 10 hours, and the leaves of the tobacco leaves on the roof are completely yellow, the main veins are completely white, and the leaves are soft and curled, with the edges curled.

[0162] Then the dry bulb temperature is raised to 47.5℃ at a rate of 0.2℃ / h, and the wet bulb temperature is 36.5℃. The temperature is kept constant for 12 hours until the tobacco leaves in the middle layer of the flue-curing room are fully yellowed and softened, and the yellow leaves and yellow tendons are rolled into small rolls.

[0163] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37.5℃, and the temperature is kept constant for 8h until the yellow leaves and yellow tendons of the tobacco leaves in the bottom shed are rolled into small rolls;

[0164] Then the dry bulb temperature is raised to 54℃ at a rate of 1.5℃ / h, the wet bulb temperature is 38.5℃, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours to reach the full-heated tobacco leaf roll;

[0165] ④ Drying stage

[0166] The dry bulb temperature is raised to 60℃ at a rate of 0.75℃ / h, the wet bulb temperature is 40℃, and the temperature is kept constant for 6 hours, so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting;

[0167] Then the dry bulb temperature is raised to 68°C at a rate of 2°C / h, the wet bulb temperature is 41°C, and the temperature is kept stable for 16 hours, until the main veins of the tobacco leaves in the entire flue-curing room are completely dry, that is, the tobacco leaves are completely dry and have no fleshy tendons, completing the task of the tendon drying stage.

[0168] Example 7

[0169] The method for harvesting and baking the tobacco leaves of the flue-cured tobacco hybrid variety YY021 with excess nutrition comprises the following steps:

[0170] (I) YY021 tobacco leaf harvesting includes the following steps:

[0171] (1) The lower tobacco leaves are harvested when they are 65 days old, slightly yellow in color, with some hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves are naturally bent, and the SPAD value of the leaves is 20.

[0172] (2) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 20 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: the leaves are 85 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 22 before harvesting the middle tobacco leaves.

[0173] (3) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves: the leaves are 100 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tips droop naturally, there is oil on the leaf surface, and the leaf SPAD value is 20, then the upper tobacco leaves are harvested;

[0174] (II) YY021 tobacco leaf baking:

[0175] (A) Yellowing due to low temperature and humidity control

[0176] After loading the tobacco leaves with excess nutrition into the curing room, close the curing room door and ignite the fire in time, and at the same time enable the high-speed gear of the circulating fan, with the fan speed of 1440 rpm;

[0177] Then the dry bulb temperature was raised to 39°C at a rate of 1°C / h, the wet bulb temperature was 38°C, the circulating fan was adjusted to low speed, the fan speed was 960 rpm, and the temperature was kept stable for 8 hours;

[0178] Then the dry bulb temperature is raised to 40℃ at a rate of 1℃ / h, and the wet bulb temperature is 37℃. The temperature is kept constant for 24 hours until the tobacco leaves turn 70% to 80% yellow.

[0179] (B) Stable temperature and moisture removal withering

[0180] Then adjust the circulating fan to high speed, with the fan speed of 1440 rpm, and then raise the dry bulb temperature to 42℃ at a rate of 0.5℃ / h, and the wet bulb temperature to 34℃, and keep the temperature stable for 16 hours, until the ceiling tobacco ribs and leaf bases are completely 90% to 10% yellow, and the tobacco leaves wither and collapse until the hook tip curls;

[0181] Then the dry bulb temperature is raised to 46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 34℃. The temperature is kept constant for 10 hours until the tobacco leaves in the lower shed turn completely yellow and curl at the edges, and the tobacco leaves in the upper shed reach small rolls.

[0182] (C) Dehydrated leaves

[0183] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 34℃, and the temperature is kept constant for 6 hours until the tobacco leaves in the lower shed reach the small rolls and the tobacco leaves in the upper shed reach the large rolls;

[0184] Then the dry bulb temperature is raised to 54°C at a rate of 1°C / h, the wet bulb temperature is 38°C, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept constant for 20 hours, until the tobacco leaves in the flue-curing room are completely dry and only the main tendons are not dry before reaching the large reel;

[0185] (D) Dry muscle period

[0186] Then the dry bulb temperature is raised to 60°C at a rate of 1°C / h, the wet bulb temperature is 41°C, and the temperature is kept constant for 10 hours to ensure that the tobacco leaves in the low temperature area reach the large roll;

[0187] Then the dry bulb temperature is raised to 68°C at a rate of 1°C / h, the wet bulb temperature is 42°C, and the temperature is kept constant for 16 hours to completely dry the tobacco leaves.

[0188] Example 8

[0189] The method for harvesting and baking the tobacco leaves of the flue-cured tobacco hybrid variety YY021 with excess nutrition comprises the following steps:

[0190] (I) YY021 tobacco leaf harvesting includes the following steps:

[0191] (1) The lower tobacco leaves are harvested when they are 60 days old, slightly yellow in color, with the hairs partially falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves are naturally bent, and the SPAD value of the leaves is 22.

[0192] (2) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 20 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: the leaves are 80 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 22 before harvesting the middle tobacco leaves.

[0193] (3) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: 95 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 22, then the upper tobacco leaves are harvested;

[0194] (II) YY021 tobacco leaf baking:

[0195] (A) Yellowing due to low temperature and humidity control

[0196] After loading the tobacco leaves with excess nutrition into the curing room, close the curing room door and ignite the fire in time, and at the same time enable the high-speed gear of the circulating fan, with the fan speed of 1440 rpm;

[0197] Then the dry bulb temperature was raised to 39°C at a rate of 1°C / h, the wet bulb temperature was 38°C, the circulating fan was adjusted to low speed, the fan speed was 960 rpm, and the temperature was kept stable for 8 hours;

[0198] Then the dry bulb temperature is raised to 40℃ at a rate of 1℃ / h, and the wet bulb temperature is 37℃. The temperature is kept constant for 48 hours until the tobacco leaves turn 70% to 80% yellow.

[0199] (B) Stable temperature and moisture removal withering

[0200] Then adjust the circulating fan to high speed, with the fan speed of 1440 rpm, and then raise the dry bulb temperature to 42℃ at a rate of 0.5℃ / h, and the wet bulb temperature to 34℃, and keep the temperature stable for 16 hours, until the ceiling tobacco ribs and leaf bases are completely 90% to 10% yellow, and the tobacco leaves wither and collapse until the hook tip curls;

[0201] Then the dry bulb temperature is raised to 46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 34℃. The temperature is kept constant for 10 hours until the tobacco leaves in the lower shed turn completely yellow and curl at the edges, and the tobacco leaves in the upper shed reach small rolls.

[0202] (C) Dehydrated leaves

[0203] Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 34℃, and the temperature is kept constant for 12h, until the tobacco leaves in the lower shed reach the small rolls, and the tobacco leaves in the upper shed reach the large rolls;

[0204] Then the dry bulb temperature is raised to 54℃ at a rate of 1℃ / h, and the wet bulb temperature is 38℃. The circulating fan is adjusted to low speed and the temperature is kept stable for 20 hours until the tobacco leaves in the flue-curing room are completely dry and only the main tendons are not dry before they can be rolled into large rolls.

[0205] (D) Dry muscle period

[0206] Then the dry bulb temperature is raised to 60°C at a rate of 1°C / h, the wet bulb temperature is 41°C, and the temperature is kept constant for 10 hours to ensure that the tobacco leaves in the low temperature area reach the large roll;

[0207] Then the dry bulb temperature is raised to 68°C at a rate of 1°C / h, the wet bulb temperature is 42°C, and the temperature is kept constant for 16 hours to completely dry the tobacco leaves.

[0208] Effect experiment 1:

[0209] 1 Experimental materials and location: YY021 tobacco leaves, experimental field of Tobacco Research Institute.

[0210] 2 Experimental design

[0211] Experiment on delayed harvesting of middle tobacco leaves

[0212] Processing settings:

[0213] Test Example 1

[0214] YY021 tobacco leaf harvesting includes the following steps:

[0215] (1) The lower tobacco leaves are harvested when they are 60 days old, slightly yellow in color, with the hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, and the leaves bending naturally.

[0216] (2) The middle tobacco leaves are harvested normally, that is, the middle tobacco leaves are harvested after the lower tobacco leaves are harvested.

[0217] Test Example 2

[0218] YY021 tobacco leaf harvesting includes the following steps:

[0219] (1) The lower tobacco leaves are harvested when they are 60 days old, slightly yellow in color, with the hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, and the leaves bending naturally.

[0220] (2) Delayed harvesting of the middle tobacco leaves, that is, after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 7 days before the middle tobacco leaves are harvested.

[0221] Test Example 3

[0222] YY021 tobacco leaf harvesting includes the following steps:

[0223] (1) The lower tobacco leaves are harvested when they are 60 days old, slightly yellow in color, with the hairs falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, and the leaves bending naturally.

[0224] (2) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days before the middle tobacco leaves are harvested; the maturity standard for middle tobacco leaves is: 75 days old, the leaf color is yellow-green with mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, and there is oily substance on the leaf surface. Harvest middle tobacco leaves.

[0225] The middle tobacco leaves of Test Example 1, Test Example 2 and Test Example 3 were selected, and each treatment was separately made into a rod and baked separately in a small oven. The baking process and parameters were the same as those in Example 5. After baking, the middle tobacco was selected for tobacco leaf quality evaluation such as appearance quality, testing and smoking evaluation.

[0226] 3 Test results

[0227] 3.1 Appearance quality of raw cigarettes

[0228] Comparing the different treatments, the appearance quality score of tobacco leaves harvested 15 days later was the highest, followed by 7 days later, and the appearance quality score of normal harvest was the lowest.

[0229] Table 1 Evaluation of the appearance quality of raw tobacco after curing

[0230] deal with color Maturity Blade structure identity Oil content Chroma Total score Test Example 1 8 8 8 7 4.5 5.2 68.70 Test Example 2 8 8.2 8.5 7.2 5 5.5 71.65 Test Example 3 8.5 8.5 8.5 7.5 5 5.5 73.50

[0231] 3.2 Main chemical components

[0232] Comparing different treatments, the content of two sugars in tobacco leaves increased with the delay of harvest time, while other indicators showed little difference.

[0233] Table 2 Comparison of chemical composition of raw tobacco after curing

[0234]

[0235] 3.3 Sensory quality evaluation

[0236] Comparing different treatments, as the harvesting time was delayed, the smoking quality of tobacco leaves improved, and the total smoking score was the highest when the harvesting time was delayed by 15 days.

[0237] Table 3 Comparison of smoking quality of raw tobacco after baking

[0238]

[0239] Note: The five indicators of aroma quality, aroma quantity, impurities, irritation and aftertaste are assigned weights of 30%, 30%, 8%, 15% and 17% respectively to calculate the total score of sensory quality (the result after conversion into a percentage system).

[0240] 4 Conclusion: With the delay of tobacco leaf harvesting time, the content of sugars and sugars in the flue-cured tobacco leaves increased, and the sensory quality also improved. Delayed harvesting is beneficial to improving the quality of tobacco leaves of YY021.

[0241] Effect experiment 2:

[0242] Comparative Example 1

[0243] The method for harvesting and baking the middle tobacco leaves of the flue-cured tobacco hybrid YY021 without excess nutrition comprises the following steps:

[0244] (I) YY021 tobacco leaf harvesting includes the following steps:

[0245] The middle tobacco leaves are harvested late, that is, after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 8 days, and the middle tobacco leaves are harvested after they are mature; the maturity standard of the middle tobacco leaves: the leaves are 73 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 20, then the middle tobacco leaves are harvested;

[0246] (II) YY021 tobacco leaf baking:

[0247] ① Yellowing stage

[0248] After the non-nutritional excess middle tobacco leaves are baked and loaded into the curing room, the curing room door is closed and curing begins. At the same time, the circulating fan high gear is enabled, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 36°C at a rate of 1°C / h, the circulating fan is switched to low gear and operates continuously, the fan speed is 960 rpm, the wet bulb temperature is 34°C, and the temperature is kept stable for 18 hours;

[0249] Then the dry-bulb temperature was raised to 37°C at a rate of 0.5°C / h, the wet-bulb temperature was 35°C, and the temperature was kept constant for 20h;

[0250] Then the dry-bulb temperature was raised to 38°C at a rate of 0.5°C / h, the wet-bulb temperature was 36°C, and the temperature was kept constant for 12h;

[0251] Then the dry-bulb temperature was raised to 40°C at a rate of 0.5°C / h, the wet-bulb temperature was 38°C, and the temperature was kept constant for 16h;

[0252] ②Color Fixation Stage

[0253] The dry bulb temperature was raised to 42°C at a rate of 0.25°C / h, the wet bulb temperature was 36°C, and the temperature was kept stable for 12 hours;

[0254] The dry bulb temperature was raised to 46°C at a rate of 0.5°C / h, the wet bulb temperature was 38°C, and the temperature was kept stable for 12h;

[0255] The dry bulb temperature was raised to 52°C at a rate of 0.5°C / h, the wet bulb temperature was 39°C, and the temperature was kept stable for 8 hours;

[0256] The dry bulb temperature was raised to 54°C at a rate of 0.5°C / h, the wet bulb temperature was 39°C, and the temperature was kept stable for 8h;

[0257] ③ Dry muscle stage

[0258] The dry bulb temperature is raised to 60°C at a rate of 1°C / h, the wet bulb temperature is 41°C, and the temperature is kept constant for 8 hours;

[0259] Then the dry bulb temperature was raised to 68°C at a rate of 2°C / h, the wet bulb temperature was 42°C, and the temperature was kept stable for 16 hours.

[0260] 1 Experimental materials and location: YY021 tobacco leaves, experimental field of Tobacco Research Institute.

[0261] 2 Experimental design

[0262] Treatment settings: Example 5, non-nutrition surplus middle tobacco leaves are harvested and baked, comparative example 1.

[0263] 3 Test results

[0264] 3.1 Appearance quality of raw cigarettes

[0265] From the perspective of different baking processes, the appearance quality of Example 5 is significantly better than that of Comparative Example 1 using the traditional baking process.

[0266] Table 4 Evaluation of the appearance quality of raw tobacco after curing

[0267] deal with color Maturity Blade structure identity Oil content Chroma Total score Example 5 8.5 8 8 7 5.5 5.5 71.50 Comparative Example 1 6 7 7.5 7 4.5 4.5 62.25

[0268] 3.2 Comparison of main economic traits

[0269] From the perspective of different baking processes, the indicators such as the proportion of high-quality smoke, the proportion of medium-high-quality smoke, and the average price of Example 5 are all better than those of Comparative Example 1.

[0270] Table 5 Comparison of economic characteristics of raw tobacco after curing

[0271]

[0272] 3.3 Sensory quality evaluation

[0273] From the perspective of different baking processes, the total score of Example 1 is significantly higher than that of Comparative Example 1.

[0274] Table 6 Comparison of smoking quality of raw tobacco after baking

[0275]

[0276]

[0277] Note: The five indicators of aroma quality, aroma quantity, impurities, irritation and aftertaste are assigned weights of 30%, 30%, 8%, 15% and 17% respectively to calculate the total score of sensory quality (the result after conversion into a percentage system).

[0278] 4 Conclusion: The leaves of the flue-cured tobacco hybrid YY021 have high chlorophyll content, high polyphenol oxidase activity, high water content, and especially high proportion of bound water in the leaves. The present invention ensures smooth discharge of bound water in YY021 tobacco leaves by delaying harvesting, increasing pre-yellowing treatment, adjusting dry-bulb and wet-bulb temperature + fan control, and achieves consistent water loss and yellowing of leaves, so that the original aroma substances are dehydrated and condensed to form aroma substances. The aroma substances are the source of aroma in the process of tobacco leaf combustion. Therefore, this baking process is beneficial to improving the quality of YY021 tobacco leaves.

[0279] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for harvesting and baking flue-cured tobacco hybrid YY021, characterized in that: The steps include: (I) YY021 tobacco leaf harvesting includes the following steps: (1) The lower tobacco leaves are harvested when they are 55-60 days old, slightly yellow in color, with the hairs partially falling off, 1 / 3 to 1 / 2 of the main veins turning white and shiny, the leaves naturally bending, and the SPAD value of the leaves being 20-24. (2) Delayed harvesting of middle tobacco leaves, i.e., after the lower tobacco leaves are harvested, the tobacco plants continue to grow for 15 days, and then the middle tobacco leaves are harvested after they are mature. The maturity standard of middle tobacco leaves is: the leaves are 70-75 days old, the leaf color is yellow-green, there are mature spots, more than 2 / 3 of the main veins turn white, 1 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tip droops naturally, there is oil on the leaf surface, and the leaf SPAD value is 18-22, then the middle tobacco leaves are harvested; (3) Delayed harvesting of upper tobacco leaves, i.e., after the middle tobacco leaves are harvested, the tobacco plants continue to grow for 10-15 days, and the upper leaves are harvested after they are mature. The maturity standard of upper tobacco leaves is: the leaves are 85-90 days old, the leaves are soft, the main veins turn white, 2 / 3 of the side veins turn white, the stem-leaf angle is 80-90 degrees, the leaf tips droop naturally, there is oil on the leaf surface, and the leaf SPAD value is 16-20, then the upper tobacco leaves are harvested; (II) YY021 tobacco leaf baking: The tobacco leaves were divided into three categories, namely, non-nutritional lower tobacco leaves, non-nutritional middle and upper tobacco leaves, and nutritious tobacco leaves; The non-nutrition excess lower tobacco leaf baking comprises the following steps: 1) Yellowing stage After loading the non-nutritional excess lower tobacco leaves into the curing room, close the curing room door and start curing. At the same time, start the high-speed gear of the circulating fan, the fan speed is 1440 rpm, and when the dry bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, the fan speed is 960 rpm, the wet bulb temperature is 37°C, and the temperature is kept stable for 1 hour, and the yellowing degree of the tobacco leaves in the high-temperature shed layer reaches 80-90%, that is, the yellow leaves have blue veins, the leaves are collapsed and soft, and more than 1 / 3 of the main veins are soft and collapsed; more than 80% of the tobacco leaves in the bottom shed are yellowed to 70-80%, and the leaves are withered and soft and not easy to break; Then the dry bulb temperature is raised to 39℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃, and the temperature is kept stable until more than 80% of the tobacco leaves in the middle and lower sheds turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse; Then the dry bulb temperature is raised to 41℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 37℃. The temperature is kept stable until more than 80% of the tobacco leaves in the middle and upper sheds turn yellow, the veins of the yellow leaves are slightly green, and 2 / 3 of the main veins are soft but not broken. The tobacco leaves in the lower shed turn yellow to 80%-90%, and 1 / 2 of the main veins are soft. The above yellowing and drying standards are met to complete the yellowing stage task; 2) Color Fixation Stage Adjust the circulating fan to high speed, fan speed 1440 rpm, dry bulb temperature rises to 42℃ at a rate of 0.25℃ / h, wet bulb temperature 35-36℃, keep the temperature stable for 12-24 hours, until the main veins of the tobacco leaves on the ceiling are completely yellow and the rolls are soft and curled with hooks and edges. The principle of yellowing tobacco leaves is: yellow leaves do not turn brown, green leaves can turn yellow, and yellow tobacco is equal to green tobacco; Then the dry bulb temperature is raised to 45-46℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 36-38℃. The temperature is kept stable for 12-24h, until the tobacco leaves on the upper shed in the flue-curing room have completed the yellowing and shrinking of the leaves, i.e., the yellow leaves and yellow tendons are rolled into small rolls. Then the dry bulb temperature is raised to 48-52℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37-39℃, and the temperature is kept stable for 8-12h, until the tobacco leaves in the lower shed of the curing room have completed yellowing and shrinking, i.e. yellow leaves and yellow tendons small rolls; Then the dry bulb temperature is raised to 54℃ at a rate of 0.5℃ / h, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, the wet bulb temperature is 37-39℃, and the temperature is kept stable for 8 hours; the upper shed tobacco leaves in the curing room turn yellow to 100%, and dry to the point that only the main veins are not dry, that is, yellow leaves and yellow tendons are large rolls; 70% of the lower shed tobacco leaves meet the above standards, and the color fixing stage task is completed; 3) Drying stage The dry bulb temperature is raised to 60℃ at a rate of 1℃ / h, the wet bulb temperature is 39-41℃, and the temperature is kept stable for 4-6 hours; so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting; Then the dry bulb temperature is raised to 67-68℃ at a rate of 1℃ / h, and the wet bulb temperature is 41-42℃. The temperature is kept stable for 12-24h, until the main veins of the tobacco leaves in the flue-curing room are completely dry, that is, the tobacco leaves are completely dry without fleshy tendons, completing the task of the tendon drying stage; The baking of the non-nutritionally excessive middle and upper tobacco leaves comprises the following steps: ① Pre-yellowing stage After the non-nutritional excess middle and upper tobacco leaves are baked and loaded into the curing room, the curing room door is closed to pre-yellow the tobacco leaves by relying on the natural temperature in the curing room. The pre-yellowing takes 18 hours, and the tip of the leaves turns yellow. Then, baking begins. At the same time, the high-speed gear of the circulating fan is enabled, and the fan speed is 1440 rpm. When the dry-bulb temperature rises to 38°C at a rate of 1°C / h, the circulating fan is switched to the low-speed gear for continuous operation, and the fan speed is 960 rpm, the wet-bulb temperature is 37°C, and the temperature is kept stable for 12-24 hours, until the yellowing of the leaves in the high-temperature shed layer reaches 80% to 90% of the blue veins or yellowing degree, and the leaves collapse and become soft; Then the dry bulb temperature is raised to 39-40℃ at a rate of 0.3℃ / h, and the wet bulb temperature is raised to 39℃, reaching 80% to 90% yellowing of tobacco leaves in the middle shed, with leaves withering and softening, more than 1 / 3 of the main veins softening and collapsing, leaves are soft and not easy to break, and the appearance shows green veins and yellow flakes; Then the dry bulb temperature is raised to 42℃ at a rate of 0.3℃ / h. During the dry bulb temperature rise period, the wet bulb temperature is maintained at 38-39℃. Then the dry bulb temperature is kept stable for 12-24h. During the dry bulb temperature stability period, the wet bulb temperature is lowered to 38℃, and more than 80% of the tobacco leaves in the bottom shed turn yellow, the leaves wilt and become soft, and more than 1 / 3 of the main veins become soft and collapse. ② Yellowing-color fixation transition stage The circulating fan is set to high speed, the fan speed is 1440 rpm, the dry bulb temperature is raised to 44℃ at a rate of 0.3℃ / h, the wet bulb temperature is 36℃, and the temperature is kept stable for 8-18h, so that more than 80% of the tobacco leaves in the bottom shed turn yellow to 90%, the veins of the yellow leaves are slightly green, 2 / 3 of the main veins become soft, the broken but unbroken branch veins become soft, and the leaves are fully collapsed; ③Color Fixation Stage The dry bulb temperature rises to 46℃ at a rate of 0.3℃ / h, the wet bulb temperature is 35.5℃, and the temperature is kept stable for 6-12h, until the tobacco leaves reach the ceiling, the main veins are completely yellow, the soft rolls are completely white, and the edges are curled; Then the dry bulb temperature is raised to 47-48℃ at a rate of 0.2℃ / h, and the wet bulb temperature is 36.5℃. The temperature is kept stable for 6-12h, until the tobacco leaves in the middle layer of the flue-curing room are fully yellowed and softened, and the yellow leaves and yellow tendons are rolled into small rolls; Then the dry bulb temperature is raised to 50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 37-38℃, and the temperature is kept stable for 6-8h, until the yellow leaves and yellow tendons of the tobacco leaves in the bottom shed are rolled into small rolls; Then the dry bulb temperature is raised to 54°C at a rate of 1.5°C / h, the wet bulb temperature is 38-39°C, the circulating fan is adjusted to low speed, the fan speed is 960 rpm, and the temperature is kept stable for 10 hours to achieve full-heated tobacco leaf large rolls; ④ Drying stage The dry bulb temperature is raised to 60℃ at a rate of 0.75℃ / h, the wet bulb temperature is 39-41℃, and the temperature is kept stable for 4-6 hours; so that the tobacco leaves in the low temperature area of ​​the flue-curing room can reach complete color setting; Then the dry bulb temperature is raised to 67-68℃ at a rate of 2℃ / h, and the wet bulb temperature is 41-42℃. The temperature is kept stable for 12-24h, until the main veins of the tobacco leaves in the flue-curing room are completely dry, that is, the tobacco leaves are completely dry without fleshy tendons, completing the task of the tendon drying stage; The baking of the nutritionally excess tobacco leaves comprises the following steps: (A) Yellowing due to low temperature and humidity control After loading the tobacco leaves with excess nutrition into the curing room, close the door of the curing room and ignite the fire in time, and at the same time enable the high-speed gear of the circulating fan, with the fan speed of 1440 rpm; Then the dry bulb temperature is raised to 38-40℃ at a rate of 1℃ / h, and the wet bulb temperature is 37-38℃. The circulating fan is adjusted to low speed, with a fan speed of 960 rpm, and the temperature is kept stable for 8 hours. Then the dry bulb temperature is raised to 39-41°C at a rate of 1°C / h, and the wet bulb temperature is 36-38°C. The temperature is kept constant for 24-48 hours until the tobacco leaves turn 70% to 80% yellow. (B) Stable temperature and moisture removal withering Then adjust the circulating fan to high speed, with the fan speed of 1440 rpm, and then increase the dry bulb temperature to 42-44℃ at a rate of 0.5℃ / h, and the wet bulb temperature to 33-35℃, and keep the temperature stable for 12-24h, until the ceiling tobacco ribs and leaf bases are completely 90% to 10% yellow, and the tobacco leaves wither and collapse until the hook tip curls; Then the dry bulb temperature is raised to 45-48℃ at a rate of 0.5℃ / h, and the wet bulb temperature is 33-35℃. The temperature is kept stable for 10 hours until the tobacco leaves in the lower shed turn completely yellow and curl at the edges, and the tobacco leaves in the upper shed reach small rolls. (C) Dehydrated leaves Then the dry bulb temperature is raised to 48-50℃ at a rate of 0.5℃ / h, the wet bulb temperature is 33-35℃, and the temperature is kept stable for 6-12h until the tobacco leaves in the lower shed reach the small rolls and the tobacco leaves in the upper shed reach the large rolls; Then the dry bulb temperature is raised to 53-54℃ at a rate of 1℃ / h, and the wet bulb temperature is 37-39℃. The circulating fan is adjusted to low speed, and the fan speed is 960 rpm. The temperature is kept stable for more than 12 hours, until the tobacco leaves in the flue-curing room are completely dry and only the main tendons are not dry before reaching the large reel. (D) Dry muscle period Then the dry bulb temperature is raised to 60-62°C at a rate of 1°C / h, the wet bulb temperature is 41-42°C, and the temperature is kept constant for 10 hours to ensure that the tobacco leaves in the low temperature area reach the large roll; Then the dry bulb temperature is raised to 67-68°C at a rate of 1°C / h, the wet bulb temperature is 41-43°C, and the temperature is kept stable for 16 hours to completely dry the tobacco leaves.

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