Fertilizing method for improving ripening resistance of upper leaves of flue-cured tobacco

Abstract

The invention relates to the technical field of agricultural cultivation, in particular to a fertilizing method for improving ripening resistance of upper leaves of flue-cured tobaccos by applying organic carbon bacterial manure, which comprises the following steps: a base fertilizer stage: mixing a base fertilizer special for tobaccos, a rapeseed cake fertilizer, potassium sulfate, a biochar base fertilizer and a soil conditioner for strip application; in the transplanting stage, on the day of transplanting and 7 days after transplanting, a hole applied fertilizer, a microbial agent and a carbon polymerized organic water-soluble fertilizer are compounded, diluted and applied; dressing compound fertilizer in deep holes 30 days after transplanting in the vigorous growing period; a compound fertilizer, potassium sulfate and a microbial agent are mixed and applied during film uncovering and ridging. The fertilizer type and the application mode in each stage realize triple collaborative innovation of charcoal-microbial agent coupling, carbon-nitrogen dynamic balance regulation and control and a soil response mechanism, the soil environment is remarkably improved, root development is promoted, and diseases are reduced, so that the ripening resistance, the yield and the quality of upper leaves are effectively improved.

Description

Technical Field

[0001] This application relates to the field of agricultural cultivation technology, specifically to a fertilization method for improving the ripening resistance of the upper leaves of flue-cured tobacco. Background Technology

[0002] Flue-cured tobacco, as an important industrial raw material crop that combines both yield and quality, occupies a core position in my country's agricultural economy. However, the long-term one-sided pursuit of yield has led to the widespread phenomenon of excessive application of chemical fertilizers, causing a series of serious soil degradation problems, including a significant decrease in soil organic matter content, a sharp decline in biodiversity, intensified acidification (pH generally decreasing by 0.8-1.2), and severe compaction. These degradation problems directly lead to poor root development and low nutrient absorption efficiency in tobacco plants, and are manifested in a significant lack of ripening endurance in the upper leaves. For example, key quality characteristics such as color, thickness, and chemical composition balance of tobacco leaves decline during the ripening process. The ripening endurance of upper leaves is crucial to their industrial usability and market value. Cultivating upper leaves that can fully "ripen" in the field is the key to the entire production process, and scientific fertilization management is the most influential link in this process. Traditional fertilization methods often lead to premature senescence of upper leaves, making it difficult to meet the growing market demand for high-quality upper leaves. Summary of the Invention

[0003] To address the problem of soil degradation in tobacco-growing areas caused by long-term excessive application of chemical fertilizers, and the resulting core bottleneck of insufficient ripening tolerance in upper tobacco leaves, this application discloses a systematic fertilization method that improves the ripening tolerance of upper tobacco leaves through the synergistic regulation of organic carbon and microbial fertilizers. This method is based on a triple synergistic innovation of precise coupling of biochar and microbial agents, dynamic regulation of carbon and nitrogen balance, and soil response mechanisms. It significantly improves the soil environment, promotes root development, and reduces disease occurrence, thereby effectively enhancing the ripening tolerance, yield, and quality of upper leaves.

[0004] This application provides a fertilization method for improving the ripening resistance of the upper leaves of flue-cured tobacco, including the following steps S1 to S4: S1. Base fertilizer stage: 7-10 days before transplanting, when ridging, mix tobacco-specific base fertilizer, rapeseed cake fertilizer, potassium sulfate, biochar base fertilizer, and soil conditioner evenly and apply in strips; The application rate of tobacco-specific base fertilizer is 600–950 kg / hm². 2 The molar ratio of N:P2O5:K2O in tobacco-specific base fertilizer is (7~8.5):(14~16):(6~7.5); the application rate of rapeseed cake fertilizer is 400~600 kg / hm. 2 The organic matter content in rapeseed cake fertilizer is 40-70 wt%; the potassium sulfate application rate is 50-100 kg / hm². 2 The application rate of biochar-based fertilizer is 400-600 kg / hm². 2The biochar-based fertilizer includes straw biochar particles and organic matter. The organic matter content is ≥50 wt%, and the straw biochar particle content is 30%~50%. The particle size distribution of the straw biochar particles is 0.2~2 mm. The soil conditioner application rate is 150~300 kg / hm². 2 ; S2. Transplanting stage: On the day of transplanting and 7 days after transplanting, mix seedling fertilizer, microbial agent and carbon polymer organic water-soluble fertilizer, and dilute with water 500 to 1000 times before watering. After application, control the carbon-nitrogen ratio of the tobacco seedling rhizosphere soil within the range of 22: (0.5 to 1.5). The application rate of seedling fertilizer is 30-60 kg / hm. 2 The application rate of microbial inoculants is 20–35 kg / hm². 2 The microbial inoculant must contain at least two of the following: nitrogen-fixing bacteria, phosphate-solubilizing bacteria, Trichoderma, Bacillus subtilis, and Bacillus mucilaginosa; the viable count in the microbial inoculant must be ≥2 billion / g; the application rate of carbon-polymerized water-soluble fertilizer is 50–80 kg / hm². 2 ; S3, First Vigorous Growth Period: 30 days after transplanting, apply compound fertilizer in deep holes in the ridge; the application rate of compound fertilizer is 130-160 kg / hm. 2 The molar ratio of N:P2O5:K2O in the compound fertilizer is (8~11):(0~6):(25~31). S4, Second Peak Period: When removing the film and mounding soil, mix and apply compound fertilizer, potassium sulfate, and microbial agents. The application rate of compound fertilizer is 130–160 kg / hm². 2 The molar ratio of N:P2O5:K2O in compound fertilizer is (8~11):(0~6):(25~31); the application rate of potassium sulfate is 280~310 kg / hm. 2 The application rate of microbial inoculants is 20–35 kg / hm². 2 .

[0005] As an example, in step S1, the application rate of tobacco-specific base fertilizer can be 600 kg / hm². 2 700kg / hm 2 750kg / hm 2 800kg / hm 2 850kg / hm 2 900kg / hm 2 Or 950 kg / hm 2 .

[0006] As an example, in step S1, the application rate of rapeseed cake fertilizer can be 400 kg / hm. 2 450kg / hm2 500kg / hm 2 550kg / hm 2 Or 600 kg / hm 2 .

[0007] As an example, in step S1, the potassium sulfate application rate can be 50 kg / hm. 2 55kg / hm 2 60kg / hm 2 65kg / hm 2 70kg / hm 2 75kg / hm 2 80kg / hm 2 85kg / hm 2 90kg / hm 2 95kg / hm 2 or 100kg / hm 2 .

[0008] As an example, in step S1, the application rate of biochar-based fertilizer can be 400 kg / hm. 2 450kg / hm 2 500kg / hm 2 550kg / hm 2 Or 600 kg / hm 2 .

[0009] As an example, in step S1, the application rate of the soil conditioner can be 150 kg / hm. 2 200kg / hm 2 250kg / hm 2 or 300 kg / hm 2 .

[0010] As an example, in step S2, the application rate of seedling fertilizer can be 30 kg / hm. 2 35kg / hm 2 40kg / hm 2 45kg / hm 2 50kg / hm 2 55kg / hm 2 or 60kg / hm 2 .

[0011] As an example, in step S2, the application rate of microbial inoculant can be 20 kg / hm. 2 25kg / hm 2 30kg / hm 2 32kg / hm 2 34kg / hm 2Or 35kg / hm 2 .

[0012] As an example, in step S2, the application rate of carbon polymer water-soluble fertilizer can be 50 kg / hm. 2 55kg / hm 2 60kg / hm 2 65kg / hm 2 70kg / hm 2 75kg / hm 2 or 80kg / hm 2 .

[0013] As an example, the weight ratio of seedling fertilizer, microbial inoculant, and carbon-polymerized organic water-soluble fertilizer can be 1:0.7:1.7, 1:0.7:1.8, 1:0.7:1.9, 1:0.8:1.8, 1:0.9:1.9, 1:0.92:1.8, 1:0.92:1.85, or 1:0.95:1.9. It can also be any other ratio within the above range.

[0014] As an example, in step S3, the application rate of compound fertilizer can be 130 kg / hm². 2 135kg / hm 2 140kg / hm 2 145kg / hm 2 150kg / hm 2 155kg / hm 2 Or 160 kg / hm 2 .

[0015] As an example, in step S4, the application rate of compound fertilizer can be 130 kg / hm. 2 135kg / hm 2 140kg / hm 2 145kg / hm 2 150kg / hm 2 155kg / hm 2 Or 160 kg / hm 2 .

[0016] As an example, in step S4, the application rate of potassium sulfate can be 280 kg / hm. 2 285kg / hm 2 290kg / hm 2 295kg / hm 2 300kg / hm 2 305kg / hm 2 Or 310 kg / hm 2 .

[0017] As an example, in step S4, the application rate of the microbial agent can be 20 kg / hm. 2 25kg / hm 2 30kg / hm 2 Or 35kg / hm 2 .

[0018] Preferably, the microbial agent is selected from anti-replanting agents or carbon microbial agents.

[0019] Preferably, based on the mass of straw biochar particles (100%), the mass percentage of straw biochar particles with a particle size distribution of 0.5–1 mm is ≥70 wt%. By further controlling the distribution of straw biochar particles with specific particle sizes, the distribution of pores can be optimized; this not only allows for the adsorption of water and nutrients, improving soil fertility and water retention, but also meets the needs of root penetration.

[0020] Preferably, the pores of the straw biochar particles are loaded with a compound microbial agent with a loading rate of ≥85%, and the compound microbial agent includes at least one of Bacillus jellyoidus, actinomycetes, and phosphate-solubilizing bacteria.

[0021] Preferably, the rapeseed cake fertilizer is a biologically fermented rapeseed cake fertilizer, the molar ratio of C to N elements in the rapeseed cake fertilizer is (35~40):1, and the pH value of the rapeseed cake fertilizer is 6.5~7.5.

[0022] Preferably, the soil conditioner includes silicon dioxide with a primary particle size ≤100nm, water-soluble calcium, and water-soluble magnesium; the mass content of silicon dioxide in the soil conditioner is ≥20%, the mass content of water-soluble calcium is ≥12%, and the mass content of water-soluble magnesium is ≥6%.

[0023] Preferably, in step S2, the seedling fertilizer, microbial agent, and carbon polymerized organic water-soluble fertilizer are compounded and diluted with water 500 to 1000 times, and then applied at a ratio of 300 mL to 310 mL per seedling.

[0024] Preferably, in step S3, compound fertilizer is applied to a hole 15-20cm deep in the ridge.

[0025] Preferably, in step S4, when the compound fertilizer, potassium sulfate, and microbial agent are mixed and applied, the content of Trichoderma in the microbial agent is adjusted according to the soil pH value; wherein, when the soil pH > 5.3, the proportion of Trichoderma in the microbial agent is controlled to be ≤ 10%; when the soil pH ≤ 5.3, the proportion of Trichoderma in the microbial agent is controlled to be 30%.

[0026] Preferably, in step S4, carbon-polymerized organic water-soluble fertilizer is applied as a top dressing according to the organic matter content in the soil; wherein, when the organic matter content in the soil is >35g / kg, the application rate of carbon-polymerized organic water-soluble fertilizer is 20~40kg / hm. 2 When the organic matter content in the soil is ≤35g / kg, the application rate of carbon polymerized organic water-soluble fertilizer is 50~80kg / hm. 2 .

[0027] Preferably, when removing the film and mounding soil, compound fertilizer, potassium sulfate, and microbial agents are spread on the surface of the ridge and mixed into the tillage layer in conjunction with the mounding soil. The soil is then deeply loosened to 20cm between rows and shallowly loosened to 8cm near the roots to break up soil compaction.

[0028] Preferably, this fertilization method is suitable for soils with a pH of 5.0 to 5.5 and an organic matter content of ≥35g / kg.

[0029] The mechanism by which this application improves the ripening resistance of the upper leaves of flue-cured tobacco through the application of organic carbon microbial fertilizer is as follows: (1) Extending the active period of microbial agents: During the basal fertilizer stage, the application of specific amounts of tobacco-specific basal fertilizer, rapeseed cake fertilizer, potassium sulfate, biochar basal fertilizer, and soil conditioner works synergistically to improve the soil, optimize the microenvironment, and provide long-term nutrient supply. Furthermore, by using biochar with a specific particle size (0.5-1mm ≥70%), high-load (≥85%) target functional bacteria (a compound microbial agent with Bacillus subtilis as the core, which has the functions of silicon solubilization, potassium solubilization, and extracellular polysaccharide production), and supplemented with dual alkali sources (biochar + nano-silicon calcium magnesium soil conditioner) to optimize the microenvironment, the effective active period of microorganisms is significantly extended to ≥35 days (conventionally ≤15 days); this ensures that the "engine" (microorganisms) of the soil ecosystem can work continuously throughout the entire flue-cured tobacco growth period, thereby stably improving the soil, supplying nutrients, promoting growth, and ultimately directly contributing to the comprehensive improvement of the upper leaf ripening resistance, yield, and quality.

[0030] (2) Precisely regulate the rhizosphere C / N ratio: During the transplanting stage, control the amount of seedling fertilizer, microbial agents, and carbon polymerized organic water-soluble fertilizer to stabilize the rhizosphere soil carbon-nitrogen ratio at 22: (0.5~1.5), maintain the dynamic balance system of carbon and nitrogen microbial community in the soil. This balance system provides the best carbon and nitrogen environment for the reproduction and function of microbial community, significantly enhances microbial activity, accelerates organic matter mineralization, and thus promotes the carbon and nitrogen metabolism balance of tobacco plants, improves soil fertility, provides a good microbial environment for the growth of flue-cured tobacco, promotes the growth of tobacco plant roots, and enhances the root absorption capacity and stress resistance.

[0031] (3) Soil threshold response mechanism: During the vigorous growth period, when removing the mulch and mounding soil, compound fertilizer, potassium sulfate, and microbial agents are applied to control the soil acidity and carbon content within a suitable range. Furthermore, based on the key thresholds of soil pH (≤5.3) and organic matter (≤35g / kg), the proportion of Trichoderma or topdressing with carbon fertilizer and controlling its dosage are dynamically adjusted to achieve precise "acid barrier resistance" and "carbon supplementation to prevent imbalance". Specifically, through "acid barrier resistance", the root system is protected, ensuring the smooth flow of nutrient absorption channels and creating a good working environment for beneficial microorganisms. A healthy root system is the foundation for delayed leaf senescence and full maturity. Through "carbon supplementation", the continuous vitality of microorganisms is ensured, nitrogen supply is stabilized, and the carbon and nitrogen metabolism of tobacco plants tends to be balanced. As a result, tobacco leaves can grow steadily, fully accumulate dry matter (starch, cellulose, etc.), and have better leaf thickness and structure, so that they do not prematurely age and turn yellow during the maturity period, and their ripening resistance is naturally greatly improved.

[0032] The technical solution of this application has the following beneficial effects: This application provides a fertilization method to improve the ripening resistance of upper leaves in flue-cured tobacco. Through a full-process fertilization strategy that combines multi-component synergistic application during the basal fertilizer stage, microbial agent regulation during the transplanting period, precise topdressing during the vigorous growth period, and soil structure improvement during the uncovering and earthing-up stage, a rhizosphere microenvironment with balanced carbon and nitrogen metabolism is constructed. This effectively enhances the physiological activity of upper tobacco leaves during the ripening period and has comprehensive advantages in improving soil degradation, optimizing the microbial community structure, and improving tobacco quality. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the implementation details and effects of the present invention are described in detail below with reference to specific embodiments. The fertilizer ratios, application methods, and effect data involved in the embodiments are all based on actual field trial results, but the scope of protection of the present invention is not limited to the following embodiments.

[0034] 1. Test Protocol The experiment was conducted in 2024 at an experimental base in Shimen, Changde, Hunan Province. The tested variety was the flue-cured tobacco variety 'Yunyan 87'. The experimental soil was mountain yellow soil. The experimental design consisted of two fertilization treatments according to the present invention (Examples 1 and 2) and one conventional fertilization control (Comparative Example 1), using a randomized block design. Each treatment was replicated three times, resulting in six plots, each 56.1 m². Floating seedlings were raised in single-row cultivation. Transplanting was done in early May, with a planting density of 55 cm between plants and 120 cm between rows. Other agronomic practices followed local standards for high-quality flue-cured tobacco production.

[0035] Fertilizer sources and characteristics: The main fertilizer is tobacco-specific base fertilizer: m(N):m(P2O5):m(K2O)=8:15:7, Hunan Jinye Zhongwang Technology Co., Ltd.

[0036] Rapeseed cake fertilizer: 40% organic matter, Hunan Jinye Zhongwang Technology Co., Ltd.

[0037] Compound fertilizer: m(N):m(P2O5):m(K2O)=10:0:32, Hunan Jinye Zhongwang Technology Co., Ltd.

[0038] Nitrogen-potassium compound fertilizer: m(N):m(P2O5):m(K2O)=13.5:0:44.5, Hunan Jinye Zhongwang Technology Co., Ltd.

[0039] Agricultural potassium sulfate fertilizer: m(N):m(P2O5):m(K2O)=0:0:52, produced by SDIC Xinjiang Lop Nur Potash Co., Ltd.

[0040] Carbon polymer organic fertilizer water-soluble fertilizer: organic matter ≥100g / L, Tianjin Saimule Import & Export Co., Ltd.

[0041] Anti-replanting agent: Effective viable count ≥ 2 billion / g, including Bacillus subtilis, Bacillus licheniformis, Bacillus amyloliquefaciens, Bacillus megaterium, and Bacillus spp. (like Bacillus spp.), Beijing Engran Environmental Technology Co., Ltd.

[0042] Carbon Microbial Agent: Effective live bacteria count ≥ 60 billion / g, containing Bacillus subtilis, Bacillus amyloliquefaciens, yeast, EM photosynthetic bacteria, etc., Tianjin Saimul Import & Export Co., Ltd.

[0043] Biochar-based fertilizer A loaded with microbial agents: contains biochar, organic matter ≥50%, straw char with a particle size of 0.5-1mm accounting for 80%, loaded with compound microbial agents in the pores, with a loading rate ≥85%, Shike Biotechnology (Shanghai) Co., Ltd.

[0044] Biochar-based fertilizer B: The main components are straw biochar and organic matter, with an organic matter content of ≥50%. The biochar particle size range is relatively wide, from 0.2 to 2 mm. It has not undergone the loading process of exogenous functional microbial agents. Henan Baihui Biotechnology Co., Ltd.

[0045] Soil conditioner: pH 8.5~9.0, particle size ~80nm, SiO2 content 22%, Shanxi Dongda Soil Technology Co., Ltd.

[0046] Example 1 Apply base fertilizer (strip application 7 days before transplanting): 900 kg / hm² of tobacco-specific base fertilizer. 2 +600 kg / hm² of rapeseed cake fertilizer 2 +75 kg / hm² of agricultural potassium sulfate fertilizer 2 +Biochar-based fertilizer A loaded with microbial agents 450 kg / hm² + Soil conditioner 160 kg / hm² 2 Weigh the ingredients according to the specified proportions, mix them thoroughly, and apply them to the soil as fertilizer.

[0047] During the transplanting stage (watering on the day of transplanting and 7 days after): apply 32.5 kg / hm² of seedling fertilizer. 2 +Anti-continuous cropping agent (effective viable bacteria count ≥ 2 billion / g) 30kg / hm 2 + 60 kg / hm of carbon polymer water-soluble fertilizer 2 Weigh out the appropriate amount of fertilizer, dilute it 800 times with water, and apply 300mL to each plant.

[0048] 30 days after transplanting: Apply compound fertilizer at a depth of 15-20cm in the ridge. 2 .

[0049] When removing the mulch and mounding soil: apply compound fertilizer at a rate of 150 kg / hm². 2 +300 kg / hm² of agricultural potassium sulfate fertilizer 2 Weigh out the anti-replanting agent (microbial agent A, ≥2 billion / g) at a ratio of 30kg / hm², mix thoroughly, and spread it, incorporating it into the topsoil during hilling. Deep loosen the soil between rows to 20cm and shallow loosen it to 8cm near the roots.

[0050] Example 2

[0051] The fertilization method in this embodiment is basically the same as that in Embodiment 1, except that the anti-replanting agent is replaced with an equal amount of carbon microbial inoculant (effective viable count ≥ 60 billion / g) during the fertilization process, and the biochar-based fertilizer A loaded with the inoculant is replaced with an equal amount of biochar-based fertilizer B. The specific fertilization method is as follows: Apply base fertilizer (7-10 days before transplanting): 900 kg / hm² of tobacco-specific base fertilizer. 2 +600 kg / hm² of rapeseed cake fertilizer 2 +75 kg / hm² of agricultural potassium sulfate fertilizer 2 +Biochar-based fertilizer B 450kg / hm² + Soil conditioner 160kg / hm² 2 Weigh the ingredients according to the specified proportions, mix them thoroughly, and apply them to the soil as fertilizer.

[0052] During the transplanting stage (watering on the day of transplanting and 7 days after): apply 32.5 kg / hm² of seedling fertilizer. 2 +Carbon Microbial Agent (Effective viable bacteria count ≥ 60 billion / g) 30kg / hm 2 + 60 kg / hm of carbon polymer water-soluble fertilizer 2 Weigh out the appropriate amount of fertilizer, dilute it 800 times with water, and apply 300mL to each plant.

[0053] 30 days after transplanting: Apply compound fertilizer at a depth of 15-20cm in the ridge. 2 .

[0054] When removing the mulch and mounding soil: apply compound fertilizer at a rate of 150 kg / hm².2 +300 kg / hm² of agricultural potassium sulfate fertilizer 2 Weigh out 30 kg / hm² of carbon-based microbial inoculant (effective live bacteria count ≥ 60 billion / g), mix thoroughly, and spread, incorporating it into the topsoil during hilling. Deep loosen the soil between rows to 20 cm and shallowly loosen it to 8 cm near the roots.

[0055] Comparative Example 1 This comparative example uses traditional, conventional fertilization methods: Apply base fertilizer (7-10 days before transplanting): 900 kg / hm² of tobacco-specific base fertilizer. 2 +600 kg / hm² of rapeseed cake fertilizer 2 +75 kg / hm² of agricultural potassium sulfate fertilizer 2 Weigh the ingredients according to the specified proportions, mix them thoroughly, and apply them to the soil as fertilizer.

[0056] Transplanting stage (watering on the day of transplanting and for the following 7 days): Apply seedling fertilizer at a rate of 32.5 kg / hm². 2 Weigh out the amount of material, dilute it with water 800 times, and water each plant with 300mL.

[0057] 30 days after transplanting: Apply compound fertilizer at a depth of 15-20cm in the ridge. 2 .

[0058] When removing the mulch and mounding soil: apply compound fertilizer at a rate of 150 kg / hm². 2 + Potassium sulfate 300 kg / hm 2 Weigh the materials according to the specified proportions, mix them thoroughly, and spread them, then incorporate them into the topsoil layer during hilling.

[0059] Analysis of Experimental Results (1) Dynamic changes in the length and width of the upper tobacco leaves after topping The tobacco plants were topped when 50% of the central flowers were open, and the changes in the length and width of the upper leaves were observed after topping. Specific results are shown in Table 1. Table 1 shows that the length and width of the upper leaves increased with time after topping, but the increase gradually decreased. The leaf length of the treatments in Examples 1 and 2 was significantly higher than that of Comparative Example 1 at all measurement time points (p<0.05). Regarding leaf width, the treatment in Example 1 was significantly wider than that in Comparative Example 1 at all time points, while the treatment in Example 2 was significantly wider than that in Comparative Example 1 at 20 and 30 days after topping. This indicates that the fertilization method provided in this application significantly promotes the growth and expansion of the upper leaves after topping.

[0060] Table 1. Dynamic changes in the length and width of upper tobacco leaves after different treatments following topping.

[0061] Note: In the table, lowercase letters a, b, c, and d indicate a significance level of 0.05; the same applies below.

[0062] (2) Dynamic changes in the dry matter content of upper tobacco leaves after topping At the time of topping, 10 days after topping, 20 days after topping, and 30 days after topping, the top 6 leaves of one tobacco plant were collected from each plot according to leaf position. The leaves were then blanched at 105℃ and dried at 70℃ to constant weight, and their dry weight was measured. The dry weight of the upper tobacco leaves in each group is shown in Table 2.

[0063] Table 2 shows that the dry matter weight of the upper tobacco leaves after topping exhibits a trend of first increasing and then slightly decreasing (especially in the middle and upper leaves). The dry matter weight of the treatment in Example 1 was significantly higher than that in Comparative Example 1 at all measurement time points (p<0.05). The dry matter weight of the treatment in Example 2 was also significantly higher than that in Comparative Example 1 at 20 and 30 days after topping. Specifically, at 30 days after topping (the critical maturity period), the dry matter weight of the treatment in Example 1 reached 11.34 g / leaf, significantly higher than the 8.14 g / leaf of Comparative Example 1.

[0064] Table 2. Dry weight of upper tobacco leaves at different time points after topping

[0065] (3) Dynamic changes in SPAD value and ripening resistance index of upper tobacco leaves after topping Five tobacco plants were selected, and the top six leaves (labeled D1 to D6 from top to bottom) were measured. Six points were selected on each leaf, avoiding the veins. The SPAD value was measured using a SPAD-502 chlorophyll meter, and the average value was taken. The SPAD value reflects the relative chlorophyll content. The ripening tolerance index = SPAD value measured on day 20 / (SPAD value measured on day 20 - SPAD value measured on day 30). The higher the index value, the better the ripening tolerance. The rate of decline is an important indicator for evaluating ripening tolerance. Table 3 shows that the SPAD values ​​of all treatments gradually decreased after topping. The SPAD values ​​of the treatments in Example 1 and Example 2 at 10, 20, and 30 days after topping were significantly lower than those of Comparative Example 1 at the same time (p<0.05), indicating that the treatment of the present invention delayed chlorophyll degradation, that is, the SPAD decline rate was slower. The calculated ripening tolerance index further confirmed that the ripening tolerance index of Example 1 and Example 2 was significantly higher than that of Comparative Example 1 by 82.47% and 38.43%, respectively.

[0066] Table 3. Dynamic changes in SPAD value and ripening resistance index of upper tobacco leaves after topping under different treatments

[0067] (4) Effects of carbon supplementation and microbial fertilizer application on the economic traits of upper tobacco leaves The tobacco leaves were graded according to the national standard for flue-cured tobacco (GB 2635-92), as shown in Table 4. The fertilization method of this application significantly improved the economic traits of the upper tobacco leaves. In terms of the proportion of top-grade tobacco, Examples 1 and 2 significantly increased by 33.32% and 26.54% respectively compared to Comparative Example 1. In terms of average price, Examples 1 and 2 significantly increased by 9.02% and 7.15% respectively compared to Comparative Example 1. In terms of yield, Examples 1 and 2 significantly increased by 6.32% and 2.23% respectively compared to Comparative Example 1. In terms of output value, Examples 1 and 2 significantly increased by 15.89% and 9.54% respectively compared to Comparative Example 1. The treatment in Example 1 (biochar loading + specific microbial agent) performed best in all economic indicators.

[0068] Table 4. Economic traits of upper tobacco leaves under different treatments

[0069] (5) The effect of microbial fertilizer application method on the appearance quality of upper tobacco leaves To evaluate the appearance quality of the upper tobacco leaves by examining the effect of fertilization methods, from The samples of cured tobacco leaves were evaluated from multiple aspects, including color, maturity, and leaf structure. Each indicator was scored (out of 10) or described qualitatively. The appearance quality index was calculated based on each indicator and significance was tested. Finally, the comprehensive performance was ranked according to the index to evaluate the effectiveness of the fertilization treatment.

[0070] The evaluation results of the appearance quality of the flue-cured tobacco leaves are shown in Table 5. The leaf structure of the treatments in Examples 1 and 2 tended to be "slightly dense," while that in Comparative Example 1 was "somewhat loose." The oil content of the treatment in Example 1 reached "present," which was significantly better than the "slightly present" of Example 2 and Comparative Example 1. The differences in color (orange-yellow), maturity (mature), type (slightly thick), and chroma (medium) among the treatments were relatively small. The treatment in Example 1 had the best appearance quality.

[0071] Table 5 Appearance quality of flue-cured tobacco leaves after different treatments

[0072] The above examples demonstrate that the effectiveness of the systematic fertilization method provided in this application has been verified in mountainous yellow soil tobacco-growing areas. Experimental results show that the triple synergistic effect of the "biochar pore-microbial inoculant carrier coupling system," "dynamic balance regulation of carbon and nitrogen microbial communities" (compound formulation during transplanting), and "soil threshold response mechanism" (dynamic adjustment during the vigorous growth period / deep loosening operation) effectively overcomes the bottleneck of premature senescence in the upper leaves of flue-cured tobacco in this region. Significantly promoted late-stage growth and dry matter accumulation: The treatments in Examples 1 and 2 significantly increased the length, width (Table 1) and dry matter weight of the upper leaves after topping (Table 2, 30 days after topping, Example 1 reached 11.34 g / leaf, significantly higher than the 8.14 g / leaf of Comparative Example 1).

[0073] Significantly improved ripening resistance: The treatment of the present invention significantly slowed down the rate of decrease of SPAD value (Table 3). The ripening resistance index of Example 1 and Example 2 increased by 82.47% and 38.43% respectively compared with Comparative Example 1.

[0074] Significantly improved economic characteristics: The treatment in this application significantly increased the proportion of superior tobacco (Example 1 +33.32%, Example 2 +26.54%), average price, yield and output value (Table 4), with the output value of Example 1 treatment increasing by 15.89%.

[0075] Optimized appearance quality: The treatment of the present invention, especially Example 1, improves the leaf structure and oil content of the flue-cured tobacco leaves, resulting in the best appearance quality (Table 5).

[0076] Extending microbial agent activity (indirect verification): Although this example did not directly measure the duration of microbial agent activity in the soil, the treatment in Example 1 (using biochar-based fertilizer loaded with specific microbial agents) showed the best performance in promoting growth (Tables 1 and 2), delaying SPAD decline (Table 3), and improving economic quality (Tables 4 and 5). In contrast, although the treatment in Example 2 used highly active carbon microbial agents, the biochar-based fertilizer B used in it was not loaded with functional microbial agents and failed to form an effective carrier synergy, so the effect was inferior to that of Example 1.

[0077] Conclusion: The systematic fertilization method of this invention, through a triple synergistic innovation mechanism, effectively promotes the growth of upper leaves and dry matter accumulation in flue-cured tobacco, significantly enhances its ripening resistance, and ultimately greatly improves the yield, output value and appearance quality of upper tobacco leaves. Specifically, in Example 1, the dry matter accumulation of the treatment compared to Example 1 increased by 39.3%, the output value increased by 15.89%, and the proportion of high-grade tobacco increased by 33.32%. This achieved a win-win situation in terms of both economic and ecological benefits (improving soil structure and promoting microbial activity), providing reliable technical support for the production of high-quality upper tobacco leaves in mountainous yellow soil tobacco-growing areas.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A fertilization method for improving the ripening resistance of the upper leaves of flue-cured tobacco, characterized in that, Includes the following steps: S1. Base fertilizer stage: 7-10 days before transplanting, when ridging, mix tobacco-specific base fertilizer, rapeseed cake fertilizer, potassium sulfate, biochar base fertilizer, and soil conditioner evenly and apply in strips; The application rate of the tobacco-specific base fertilizer is 600–950 kg / hm². 2 The molar ratio of N:P2O5:K2O in the tobacco-specific base fertilizer is (7~8.5):(14~16):(6~7.5). The application rate of rapeseed cake fertilizer is 400-600 kg / hm². 2 The organic matter content in the rapeseed cake fertilizer is 40-70 wt%. The potassium sulfate application rate is 50–100 kg / hm². 2 ; The application rate of the biochar-based fertilizer is 400-600 kg / hm². 2 The biochar-based fertilizer includes straw biochar particles and organic matter components, wherein the organic matter components have a mass percentage content of ≥50wt%, the straw biochar particles have a mass percentage content of 30%~50%, and the straw biochar particles have a particle size distribution of 0.2~2mm. The application rate of the soil conditioner is 150~300 kg / hm²; S2. Transplanting stage: On the day of transplanting and 7 days after transplanting, mix seedling fertilizer, microbial agent and carbon polymer organic water-soluble fertilizer, and dilute with water 500 to 1000 times before watering. After application, control the carbon-nitrogen ratio of the tobacco seedling rhizosphere soil within the range of 22: (0.5 to 1.5). The application rate of the seedling fertilizer is 30-60 kg / hm. 2 ; The application rate of the microbial agent is 20–35 kg / hm. 2 The microbial agent includes at least two of nitrogen-fixing bacteria, phosphate-solubilizing bacteria, Trichoderma, Bacillus subtilis, and Bacillus mucilaginosus, and the number of live bacteria in the microbial agent is ≥2 billion / g; The application rate of the carbon polymer water-soluble fertilizer is 50–80 kg / hm². 2 ; The weight ratio of the seedling fertilizer, the microbial agent, and the carbon polymerized organic water-soluble fertilizer is 1:(0.7~0.95):(1.7~1.9). S3, First Vigorous Growth Period: 30 days after transplanting, apply compound fertilizer in deep holes in the ridge; the application rate of the compound fertilizer is 130-160 kg / hm. 2 The molar ratio of N:P2O5:K2O in the compound fertilizer is (8~11):(0~6):(25~31). S4. Second peak growth period: When removing the film and cultivating the soil, mix and apply the compound fertilizer, potassium sulfate and the microbial agent. The application rate of the compound fertilizer is 130–160 kg / hm². 2 The molar ratio of N:P₂O₅:K₂O in the compound fertilizer is (8~11):(0~6):(25~31); the application rate of potassium sulfate is 280~310 kg / hm². 2 The application rate of the microbial agent is 20–35 kg / hm². 2 .

2. The fertilization method according to claim 1, characterized in that, The microbial agent is selected from anti-replanting agents or carbon microbial agents.

3. The fertilization method according to any one of claims 1 to 2, characterized in that, Based on the mass of the straw biochar particles as 100%, the mass percentage of straw biochar particles with a particle size distribution of 0.5 to 1 mm is ≥70 wt%.

4. The fertilization method according to claim 3, characterized in that, The pores of the straw biochar particles are loaded with a compound microbial agent with a loading rate of ≥85%. The compound microbial agent includes at least one of Bacillus jellyoidus, actinomycetes, and phosphate-solubilizing bacteria.

5. The fertilization method according to any one of claims 1 to 2 and 4, characterized in that, In step S4, when the compound fertilizer, potassium sulfate, and the microbial agent are mixed and applied, the content of Trichoderma in the microbial agent is adjusted according to the soil pH value measured at this time; wherein, when the soil pH > 5.3, the proportion of Trichoderma in the microbial agent is controlled to be ≤ 10%; when the soil pH ≤ 5.3, the proportion of Trichoderma in the microbial agent is controlled to be 30%.

6. The fertilization method according to any one of claims 1 to 2, 4, characterized in that, In step S4, the carbon-polymerized organic water-soluble fertilizer is applied as a top dressing based on the organic matter content in the soil at this time; wherein, when the organic matter content in the soil is >35g / kg, the application rate of the carbon-polymerized organic water-soluble fertilizer is 20~40kg / hm²; when the organic matter content in the soil is ≤35g / kg, the application rate of the carbon-polymerized organic water-soluble fertilizer is increased to 50~80kg / hm². 2 .

7. The fertilization method according to any one of claims 1 to 2, 4, characterized in that, When removing the film and mounding soil, the compound fertilizer, potassium sulfate, and microbial agent are spread on the surface of the ridge and mixed into the tillage layer. The soil between the rows is deeply loosened to 20cm, and the soil near the roots is loosened to 8cm to break up the soil compaction.

8. The fertilization method according to any one of claims 1 to 2, 4, characterized in that, The rapeseed cake fertilizer is a biologically fermented rapeseed cake fertilizer, and the molar ratio of C to N elements in the rapeseed cake fertilizer is (35~40):1, and the pH value of the rapeseed cake fertilizer is 6.5~7.

5.

9. The fertilization method according to any one of claims 1 to 2, 4, characterized in that, The soil conditioner comprises silicon dioxide with a primary particle size ≤100nm, water-soluble calcium, and water-soluble magnesium; the mass content of the silicon dioxide in the soil conditioner is ≥20%, the mass content of the water-soluble calcium is ≥12%, and the mass content of the water-soluble magnesium is ≥6%.

10. The fertilization method according to any one of claims 1 to 2, 4, characterized in that, The method is applicable to soils with a pH of 5.0-5.5 and an organic matter content of ≥35g / kg.

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