Application of exogenous complexing control measures in reducing low-temperature early flowering of tobacco

Abstract

The application of exogenous complex control measures in reducing tobacco low temperature early flowering, after tobacco transplanting, before the arrival of low temperature cold damage, exogenous complex measures solution is sprayed; the exogenous complex chemical measures solution is the mixed solution of magnesium sulfate and salicylic acid. The invention uses low temperature sensitive tobacco variety Yunyan 87 as experimental material, compares and analyzes the changes of leaf phenotype, physiology and biochemistry indexes of Yunyan 87 seedlings under low temperature stress and various exogenous material treatment, and confirms the role of the complex measures in resisting cold stress. The low temperature adversity resistance of tobacco seedling stage plants is improved by using suitable concentration magnesium sulfate to spray the tobacco seedlings, so that the growth state of the tobacco seedlings subjected to the low temperature adversity stress of the reverse spring cold tends to be normal, the frost injury and frost death phenomenon of the tobacco seedlings after the cold stress is reduced, the cold resistance of the tobacco seedling stage is improved, the early flowering in the later period is prevented, and the operation is simple, the cost is low, and the effect is obvious.

Description

TECHNICAL FIELD

[0001] The application relates to the tobacco planting technical field, and particularly relates to application of exogenous complex control measures in reduction of early flowering of tobacco under low temperature. BACKGROUND

[0002] Tobacco (Nicotiana tabacum L.) is a kind of warm crop originated from tropical and subtropical regions, and is sensitive to environmental temperature change and poor in tolerance to low temperature stress. Since tobacco seedlings are usually cultivated in early spring, most southern tobacco areas in China are in cold and rainy climate, and the meteorological conditions of low temperature and little sunshine, so the tobacco seedlings are often damaged by the “late spring cold”. The “late spring cold” leads to poor growth of tobacco plants in the “seedling stage and root elongation stage” and induces occurrence of early flowering, which seriously affects the yield and quality of tobacco leaves and has been restricting the development of high-quality tobacco production.

[0003] The tobacco seedlings suffer a series of damages after experiencing low temperature: the tobacco seedlings may be frozen to death due to too low temperature; the low temperature stress leads to prolongation of seedling time and postponement of transplanting period, so that the high temperature at the late growth stage in the field is forced to ripen seriously, and root stem diseases such as tobacco bacterial wilt are easily induced; the leaf of the tobacco plant as a harvested organ, the low temperature causes the reproductive growth of the tobacco plant to be advanced, and the early flowering phenomenon is induced, leading to a decrease in the yield of tobacco leaves. Meanwhile, the production practice also proves that the environmental temperature is the most critical ecological factor affecting the quality and flavor of tobacco leaves in different production areas in China. At present, the K326 and Yunyan 87 and other main tobacco varieties popularized in production have relatively excellent comprehensive traits, but they are poor in tolerance to low temperature environment. In summary, the tobacco seedlings suffering from cold stress at the seedling stage will seriously affect the yield and quality of tobacco leaves, which is an important practical problem in the production of flue-cured tobacco in China.

[0004] In view of the actual problem of frequent cold damage in tobacco production, the following solutions are currently available. First, genetic improvement can be used to improve cold tolerance by breeding new varieties with strong cold tolerance and using them to change the germplasm and increase cold tolerance. However, the tobacco germplasm with low temperature tolerance required for genetic improvement is relatively scarce, and the breeding cycle is long. It requires a lot of manpower, material resources and financial resources to breed varieties with excellent cold tolerance, excellent agronomic traits and yield. Moreover, since the current tobacco planting and curing supporting measures are already well established, replacing the variety requires a series of corresponding measures, so the feasibility of breeding and replacing new varieties in production is low. For seedling stage low temperature, most crops use some agronomic measures to alleviate the problem, including increased base fertilizer and reduced field waterlogging, and some vegetables use measures such as building a warm shed. However, these measures generally require a large amount of manpower and material resources, and due to the uncertainty of low temperature weather, it may not be effective to take such agronomic measures, and it may even result in waste of production materials. Therefore, there is an urgent need for a simple, easy-to-implement, low-cost and effective cold resistance measure for tobacco production. SUMMARY

[0005] The purpose of the present application is to provide a method for reducing the loss of tobacco caused by cold damage and reducing the early flowering phenomenon, in order to solve the problems raised in the above background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] An exogenous complex control measure,

[0008] After the tobacco is transplanted, the exogenous complex measure solution is sprayed before the low temperature cold damage occurs; the exogenous complex chemical measure solution is a mixture of magnesium sulfate and salicylic acid,

[0009] The spraying amount is 12-15 mL per plant for transplanted tobacco;

[0010] The spraying degree is that the tobacco leaves form beads and condense but do not flow down in strands;

[0011] The spraying frequency is 1-3 times of spraying before the cold damage occurs, once a day.

[0012] The spraying low temperature range is 1-15℃.

[0013] The mixture of magnesium sulfate and salicylic acid, wherein the magnesium sulfate is a mixture of magnesium sulfate heptahydrate and ultrapure water, and the salicylic acid is a salicylic acid solution in anhydrous ethanol or 95% ethanol.

[0014] The mixed solution of magnesium sulfate and salicylic acid is a mixed solution of a salicylic acid solution with a concentration of 1 mmol / L and a magnesium sulfate solution with a concentration of 0.5%.

[0015] The preparation method of the spraying solution is to dissolve 0.15 g of salicylic acid solid and 5 g of magnesium sulfate heptahydrate solid in 1 L of water, wherein the salicylic acid solid is dissolved with 0.2 mL of anhydrous ethanol.

[0016] The surfactant is 0.1% Tween-20 mixed by volume.

[0017] The spraying time is before 10 o'clock in the morning or after 4 o'clock in the afternoon every day.

[0018] Preferably, spraying is carried out on overcast days.

[0019] The configuration time of the mixed solution of magnesium sulfate and salicylic acid is greater than 24 hours from the spraying time. This can avoid insufficient dissolution leading to leaf burning after application. Other ways that can make the solution dissolve uniformly can also be used.

[0020] Beneficial effects:

[0021] If the tobacco seedlings encounter continuous low temperature (≤13℃ for more than 2 days) at the 6-12 leaf stage to about 10 days after transplanting, the flower bud differentiation will be accelerated, and the tobacco plants will be forced to enter the reproductive growth stage. Low temperature superimposed on short day will exacerbate the early flowering phenomenon.

[0022] The present application is based on production practice and laboratory and field test, and proves that the use of appropriate concentration of magnesium sulfate for foliar spraying of tobacco seedlings can improve the low temperature stress resistance of tobacco seedlings, promote the growth of tobacco seedlings under low temperature stress, reduce the frost damage and frost death of tobacco seedlings after cold stress, and has the characteristics of simple operation, low cost and obvious effect. It has good application prospect and application potential in tobacco production, and can effectively avoid the low temperature early flowering of tobacco plants.

[0023] Magnesium sulfate can improve the low temperature adaptability of tobacco by stabilizing the structure of chloroplasts (maintaining the content of chlorophyll) and enhancing the activity of root system; salicylic acid can induce the expression of stress-resistant proteins and reduce membrane lipid peroxidation (MDA content reduction of 15%-20%) caused by low temperature.

[0024] Magnesium sulfate heptahydrate can increase the concentration of magnesium ions and alleviate magnesium deficiency caused by low temperature, and salicylic acid can activate the calcium signaling pathway and synergistically regulate the expression of low temperature response genes. The use of the two in combination can also reduce the electrolyte leakage rate induced by low temperature.

[0025] Exogenous magnesium sulfate solution can significantly reduce the direct damage of low temperature to tobacco leaves and reduce the frost damage area, and the use of the combination of magnesium sulfate solution and salicylic acid solution can further improve the effect. Attached Figure Description

[0026] To more clearly illustrate the solutions in this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Phenotypes of different treatments after 3 days of external application of salicylic acid and cold stress;

[0028] Figure 2 Statistics on the number of wilted leaves in each treatment after 3 days of external application of salicylic acid and cold stress;

[0029] Figure 3 Phenotypes of different treatments under external magnesium sulfate cold stress for 3 days;

[0030] Figure 4 Statistics on the number of wilted leaves in each treatment after 3 days of external application of magnesium sulfate and cold stress;

[0031] Figure 5 To restore the frostbite phenotypes of each treatment over 3 days;

[0032] Figure 6 Phenotypic results of cold stress resistance under different treatments for three days;

[0033] Figure 7 Conductivity of each treatment for three days of cold stress;

[0034] Figure 8 The activity of antioxidant enzymes was measured in each treatment for three days of cold stress. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0037] Reference to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a common or identical embodiment. One of skill in the art will understand that the embodiments described herein can be combined with other embodiments in various ways.

[0038] In order to make the person skilled in the art better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings.

[0039] An exogenous complex control measure and its application,

[0040] After tobacco is transplanted, the exogenous complex measure solution is sprayed before the low temperature cold damage comes; the exogenous complex chemical measure solution is a mixed solution of magnesium sulfate and salicylic acid, the spraying amount is 12-15 mL per plant of transplanted tobacco, the spraying degree is that the beads on the tobacco leaves are condensed but not flowing, the spraying frequency is 1-3 times of spraying before the cold damage comes, once a day, and the spraying applicable low temperature range is 1-15℃.

[0041] The mixed solution of magnesium sulfate and salicylic acid, wherein the magnesium sulfate is a mixed solution of magnesium sulfate heptahydrate and ultrapure water, and the salicylic acid is a salicylic acid solution in anhydrous ethanol or 95% ethanol. The mixed solution of magnesium sulfate and salicylic acid is a mixed solution of a salicylic acid solution with a concentration of 1 mmol / L and a magnesium sulfate solution with a concentration of 0.5%.

[0042] The surfactant is mixed into the configured exogenous complex chemical measure solution, the surfactant is 0.1% Tween-20 by volume. The spraying time is before 10 am or after 4 pm every day. Preferably, it is sprayed on overcast days.

[0043] The configuration time of the mixed solution of magnesium sulfate and salicylic acid is greater than 24 hours from the spraying time. It can avoid the burning of the leaves after application caused by insufficient dissolution. Other ways that can make the solution uniformly dissolved can also be used.

[0044] The effect and principle of the mixed solution of exogenous magnesium sulfate and salicylic acid are explained according to the experimental process.

[0045] Example 1: Effect of different concentrations of exogenous salicylic acid on the cold tolerance of tobacco

[0046] Tobacco seedling cultivation: select the same size and full tobacco seeds harvested at the same time, sterilize with 75% alcohol for 1 min,

[0047] The sterilized tobacco seeds are sowed into 50-hole seedling trays filled with high-temperature sterilized nutrient soil by water sowing method, and the amount of seeds in each hole is controlled to be 3-4. After the substrate soil is fully watered, the cover is covered to keep warm and humid, and the seedlings are incubated in an incubator.

[0048] When the tobacco seeds germinate to the cotyledon fully unfolded, the seedlings are transplanted into the seedling pots filled with the seedling substrate, the temperature of the incubator is set to 26℃ / 24℃, the humidity is set to 40%, the light intensity is 10000 Lx, and the light cycle is set to 16h light and 8h darkness for continuous culture.

[0049] When the tobacco seedlings grow to the three-leaf one-heart to four-leaf one-heart stage, i.e. the cold-sensitive stage of tobacco, the tobacco seedlings with consistent growth are selected for standby.

[0050] Applying exogenous magnesium sulfate: 0.5g, 1g, and 2g of magnesium sulfate heptahydrate are weighed, dissolved in ultrapure water, and then transferred into 100mL volumetric flasks for constant volume. After constant volume, 100μL of Tween-20 is added to each, and after thorough mixing, it is left overnight for standby.

[0051] Three days before cold treatment, 16 tobacco seedlings with consistent growth are selected for each treatment of each variety, and different concentrations of magnesium sulfate are treated from 8am to 10am every day. The treatment is performed 3 times in 3 days, and the spraying should be uniform and comprehensive to ensure that the spraying liquid is evenly distributed on each leaf. The spraying liquid needs to be mixed again before spraying, and the water group is sprayed with ultrapure water.

[0052] Cold stress treatment: After three days of spraying, the incubator temperature is adjusted to 4℃ / 4℃, the light intensity is 10000 Lx, and the light cycle is set to 16h light and 8h darkness for cold stress treatment.

[0053] In order to explore the actual role of different concentrations of exogenous salicylic acid on cold stress, the tobacco varieties 'NC567' and 'Taizyan No. 8' with strong cold tolerance and cold-sensitive varieties were selected as materials, and five concentrations of exogenous salicylic acid were set, including water (CK), 0.25mmol / L, 0.5mmol / L, 1mmol / L, and 1.5mmol / L. After three days of spraying, cold stress treatment was performed ( Figure 1 ), and then the number of wilted leaves of each treatment after 3 days of cold stress was counted ( Figure 2 ).

[0054] From the phenotype and wilted leaf number data, it can be found that first, the cold tolerance of tobacco variety 'NC567' is obviously better than that of tobacco variety 'Taian No.8', which can be seen from the wilted leaf number and phenotype. Compared with the spraying of water group, the three low to high concentrations of exogenous salicylic acid can improve the cold tolerance of the above two varieties of tobacco seedlings, and this improvement of cold tolerance shows a clear change trend with the change of concentration, whether it is too low concentration or too high concentration, which will affect the improvement effect. At the optimum concentration (1 mmol / L), exogenous salicylic acid can obviously reduce the wilted leaf number of tobacco seedlings and improve the cold resistance.

[0055] Example 2 Effect of different concentrations of exogenous magnesium sulfate on the improvement of tobacco cold tolerance

[0056] Cold stress recovery: After cold treatment for 7 days, the culture conditions were adjusted to 26℃ / 24℃, the humidity was set to 40%, the light intensity was 10000Lx, and the light period was set to 16h light and 8h dark for recovery.

[0057] In order to explore the actual role of different concentrations of exogenous magnesium sulfate on cold stress, the tobacco germplasm with strong cold tolerance 'NC567' and cold-sensitive variety 'Taian No.8' were selected as materials, and four concentrations of exogenous magnesium sulfate were set, including water, 0.5% (CK), 1%, and 2%. After spraying for three days, cold stress treatment was carried out ( Figure 3 ), and then the wilted leaf number of each treatment after 3 days of cold stress was counted ( Figure 4 ).

[0058] From the phenotype and wilted leaf number data, it can be found that compared with the spraying of water group, the three low to high concentrations of exogenous magnesium sulfate can improve the cold tolerance of the above two varieties of tobacco seedlings, but this improvement is not increased with the increase of concentration, on the contrary, the spraying of low concentration (0.5%) of exogenous magnesium sulfate has more obvious and significant improvement ability compared with the spraying of water and other concentrations of magnesium sulfate.

[0059] At the same time, after cold treatment for 7 days and recovery for 2 days, the phenotype observation of cold stress recovery showed that compared with the spraying of water, exogenous magnesium sulfate can reduce the frost injury area of tobacco leaves after cold stress ( Figure 5 ).

[0060] Example 3 Effect of different exogenous substances on the cold tolerance of tobacco

[0061] Extraction of crude enzyme solution: 0.1 g of fully expanded functional leaves were weighed, and liquid nitrogen was added to a pre-cooled mortar to grind them into a powder. 1 mL of 4°C pre-cooled phosphate buffer solution with a concentration of 150 mM / L and pH = 7.8 was added, and the homogenate was transferred to a 2 mL centrifuge tube. Centrifugation was performed at 12000 rpm and 4°C for 15 minutes. The supernatant was the crude enzyme extract. The obtained supernatant was aliquoted and stored in a 4°C refrigerator for later use.

[0062] To explore the effects of different types of exogenous chemical measures on the cold tolerance of tobacco seedlings, as well as the actual role of magnesium sulfate on the cultivated variety 'Yunyan 87' and the interaction between different chemicals, we selected two other exogenous chemicals (SA, CaNO3) commonly used to improve cold tolerance in addition to magnesium sulfate. Four other spraying measures were developed in addition to magnesium sulfate for comparison.

[0063] The experiment began with the setting of five groups: CK (sprayed with sterilized water), SA (sprayed with 1 mmol / L salicylic acid), Mg (sprayed with 0.5% magnesium sulfate), Ca (sprayed with 30 mmol / L calcium nitrate), SA+Mg (sprayed with a mixture of 1 mmol / L salicylic acid and 0.5% magnesium sulfate), and SA+Ca (sprayed with a mixture of 1 mmol / L salicylic acid and 30 mmol / L calcium nitrate). The cultivation method, solution preparation, and cold stress treatment conditions were the same as in Example 1. The experimental variety was 'Yunyan 87'.

[0064] After three days of spraying, the plants were subjected to 4°C cold treatment for three days, and the phenotype was collected. It was found that the four exogenous chemical treatments significantly improved the cold tolerance of tobacco compared to CK ( Figure 6 ). After statistical analysis of the conductivity of each treatment, it was found that the conductivity of tobacco seedlings after low temperature stress was significantly lower than that of CK after SA+Mg spraying, and compared to SA, Ca, and Mg single spraying measures, SA+Mg had a more significant effect on cold tolerance ( Figure 7 )。

[0065] To better explore and compare the effects of each treatment on cold tolerance, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were also statistically analyzed ( Figure 8 ). It was found that compared to CK, SA+Mg significantly improved the activity of antioxidant enzymes, and high antioxidant enzyme activity explained the improvement in cold tolerance of tobacco. Moreover, compared to single measures, the combined measures had a more significant effect, which explained the reason for the significant improvement in cold tolerance from a physiological perspective.

[0066] Example 4 Exogenous complex chemical measures can alleviate the damage of tobacco seedlings under freezing injury

[0067] This example was carried out in a tobacco growing area in Jiaoling County, Meizhou City, Guangdong Province on January 15, 2025, and the test variety was 'Yunyan 87'. Jiaoling County conducts transplanting at the beginning of each year, and after transplanting, tobacco seedlings are often affected by low temperature, affecting tobacco growth, and in extreme cases, extremely low temperature can cause large-scale frost injury and death of tobacco seedlings. On January 15, 2025, Jiaoling County suffered from extremely low temperature after transplanting, and the minimum temperature after transplanting was 2℃ and 3℃ respectively. In terms of experimental design, six field treatments were set up, including spraying clean water, SA, MgSO4, CaNO3, SA+MgSO4, and SA+CaNO3 after transplanting, with three replicates for each treatment. The concentration and preparation of the spraying liquid were the same as in Example 2, and only one spraying was performed. Seven days after transplanting, a large-scale replanting was carried out, and the frost injury and death of tobacco seedlings were counted (Table 1).

[0068] Table 1 Frost injury and death rate statistics of different treatments

[0069]

[0070] From the statistical data, it can be clearly seen that extremely low temperature has a great impact on tobacco production in the tobacco growing area, and the subsequent replanting caused by severe low temperature brings excessive manpower and economic damage to production, which is an important factor that harms tobacco production. According to the total statistics table (Table 2), compared with CK, each treatment reduced the frost injury rate and frost death rate of tobacco seedlings under cold stress, among which the spraying of exogenous salicylic acid combined with magnesium sulfate was the most obvious, with a frost death rate reduction of 8.77% and a frost injury rate reduction of 22.81%. The implementation is simple and the effect is significant.

[0071] Table 2 Total statistics of frost injury and death rate of different treatments

[0072] Freeze mortality Freeze injury Fresh water 21.05％ 64.04％ SA 17.54％ 44.74％ MgSO4 14.91％ 42.11％ CaNO3 17.54％ 54.39％ SA+MgSO4 12.28％ 41.23％ SA+CaNO3 21.05％ 57.02％

[0073] Meanwhile, taking 1000 seedlings per mu, 14 mL per plant, and 14 L of spraying liquid per mu as the standard, the cost of single spraying of each treatment and common frost protection agents on the market was calculated (Table 3). It can be found that compared with other commercially available frost protection agents, the exogenous composite chemical measure (SA+MgSO4) has a higher cost than the single application of magnesium sulfate or salicylic acid, but the cost is still low compared with other measures, and the effect is verified. The test results are significant, the mitigation effect on frost injury and frost death rate is obvious, there are actual field data and laboratory data authentication, and the commercially available products have no clear experimental data support. And the configuration of the exogenous composite chemical measure (SA+MgSO4) designed by us is more simple and convenient to calculate, and the chemical substances as raw materials do not involve regulation and are easy to purchase. It is a new type of exogenous composite chemical spraying measure to reduce low temperature damage to tobacco seedlings, which is simple to operate, obvious in effect, and economical and practical.

[0074] Table 3 Economic cost calculation of different exogenous chemical control measures

[0075] Note: All the above goods are mainly purchased directly from regular channels.

[0076] Example 5 Exogenous composite chemical measure can promote growth and inhibit early flowering after seedlings suffer from low temperature

[0077] This example was transplanted to a tobacco growing area in Dabu County, Meizhou City, Guangdong Province on January 29, 2024, and the corresponding exogenous chemical measures were sprayed after transplanting. The test variety was ‘Yunyan 87’, and the data during the vigorous growth period (before topping) were counted on March 19, 2024, and the data after topping (before harvest) were counted on May 6, 2024. Meizhou tobacco growing area also suffered from low temperature in 2024, which was different from the extreme frost damage in 2025. In 24, it was mainly a long period of continuous low temperature, which also led to the occurrence of early flowering in some tobacco growing areas in Meizhou in 24.

[0078] In order to further understand the effects of different cold-resistant measures on tobacco growth and development and early flowering, the agronomic traits and present budding plant number of each treatment under six different exogenous chemical substances (CK, SA, MgSO4, CaNO3, SA+MgSO4, SA+CaNO3) were counted during the vigorous growth period (before topping) (Table 4). It can be seen from the data that the exogenous chemical measures all improve the growth potential of tobacco during the seedling stage to the vigorous growth period to some extent, among which the exogenous composite chemical measure (SA+MgSO4) prepared in this patent has the most obvious promoting effect. And through the present budding rate of CK, it is found that the exogenous composite chemical measure significantly delays the present budding period and reduces the present budding rate at the same period. And the reduction degree is obvious, which is as high as 33.83% compared with CK.

[0079] At the same time, in order to better evaluate the effect of different exogenous measures on reducing early flowering, the agronomic characters before harvesting after topping are counted in this embodiment (Table 5). From the data of effective leaf number, it can be found that compared with CK, spraying exogenous composite chemical measures (SA+MgSO4) effectively reduces the occurrence of early flowering, keeps the effective leaf number at a relatively normal level in production, reduces economic damage and ensures the safety of tobacco production.

[0080] Table 4 Agronomic characters of different exogenous chemical measures in the vigorous growth period

[0081]

[0082] Table 5 Agronomic characters of different exogenous chemical measures in the mature period

[0083] In summary, the present application formulates a new, economical, simple and effective method for reducing low-temperature damage and inhibiting early flowering of tobacco seedlings by using exogenous composite chemical measures, based on the actual production needs, laboratory simulation research and real production test.

[0084] Obviously, the above-described embodiments are only part of the embodiments of the present application, rather than all the embodiments, and the preferred embodiments of the present application are given in the drawings, but do not limit the patent scope of the present application. The present application can be realized in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments, or make equivalent replacements to some technical features. Any equivalent structure made by using the content of the present application specification and drawings, directly or indirectly applied to other related technical fields, is also within the patent protection scope of the present application.

Claims

1. An exogenous complex control measure, characterized in that: the exogenous complex control measure solution is sprayed before low temperature cold damage comes after tobacco is transplanted; the exogenous complex chemical measure spraying solution is a mixed solution of magnesium sulfate and salicylic acid, the spraying amount is 12-15 mL per plant for transplanted tobacco, the spraying degree is that the spraying solution forms beads and condensation on the tobacco leaves but does not form streams, the spraying frequency is 1-3 times of spraying before the cold damage comes, once a day, the applicable temperature range for spraying to improve cold resistance is 1℃-15℃ of the environmental temperature, the mixed solution of magnesium sulfate and salicylic acid is a mixed solution of magnesium sulfate heptahydrate and ultrapure water, and the salicylic acid is a salicylic acid solution in anhydrous ethanol or 95% ethanol, the mixed solution of magnesium sulfate and salicylic acid is a mixed solution of a 1 mmol / L salicylic acid solution and a 0.5% magnesium sulfate solution, the preparation method of the spraying solution is to dissolve 0.15 g of salicylic acid solid and 5 g of magnesium sulfate heptahydrate solid in 1 L of water, wherein the salicylic acid solid is dissolved with 0.2 mL of anhydrous ethanol.

2. The exogenous complex control measure of claim 1, wherein a surfactant is mixed in the prepared exogenous complex chemical measure solution, and the surfactant is 0.1% Tween-20 by volume.

3. The exogenous complex control measure of claim 1, wherein the spraying time is before 10 o'clock in the morning or after 4 o'clock in the afternoon.

4. The exogenous complex control measure of claim 1, wherein the spraying is performed on overcast days.

5. The exogenous complex control measure of claim 1, wherein the preparation time of the mixed solution of magnesium sulfate and salicylic acid is 24 hours earlier than the spraying time.

6. The use of the exogenous complex control measure of any one of claims 1-5 in reducing early flowering of tobacco under low temperature. ​ ​ ​ 2. The exogenous complexation control measure of claim 1, wherein: ​ 3. The exogenous complexation control measure of claim 1, wherein: ​ 4. The exogenous complexation control measure of claim 3, wherein: ​ 5. The exogenous complexation control measure of claim 1, wherein: ​ ​

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