Flue-cured tobacco and chive intercropping planting method and application of flue-cured tobacco and chive intercropping planting method in tobacco field root rot relieving

Abstract

The invention discloses a planting method for intercropping flue-cured tobacco and chive and application of the planting method in relieving root rot of a tobacco field. Belongs to the technical field of agricultural planting and comprises the steps of transplanting flue-cured tobaccos in mid-to-late April, transplanting chive seedlings to two sides of tobacco ridges within 7 days after tobacco plants are transplanted, regularly harvesting chives, harvesting tobacco leaves on the upper portions of the tobacco plants in September, pulling out tobacco stems in late October, and immediately preparing soil and sowing green manure; the green manure plants are ploughed in the soil to be decomposed, flue-cured tobacco is planted in April, and the steps are repeated in sequence. The method is easy to operate, the microenvironment of organic carbon, enzyme activity and microorganisms of rhizosphere soil of tobacco plants in the tobacco field can be improved, the multiple cropping index of the soil in the tobacco field is increased, meanwhile, soil-borne diseases caused by long-term single cropping of the flue-cured tobaccos in the tobacco field can be inhibited, and effective technical guarantee is provided for sustainable production of the flue-cured tobaccos.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting, specifically relating to a planting method for intercropping scallions with flue-cured tobacco and its application in reducing root rot in tobacco fields. Background Technology

[0002] In recent years, the excessive use of fertilizers and long-term continuous cropping in flue-cured tobacco fields have caused problems such as soil nutrient imbalance, frequent occurrence of soil-borne diseases, changes in soil microbial flora and diversity, and accumulation of autotoxic substances, resulting in aggravated flue-cured tobacco diseases and a decline in yield and quality.

[0003] Root rot in flue-cured tobacco, caused by *Thielaviopsis basicola* and *Fusarium* spp., primarily damages the root system, causing black rot. In many tobacco-growing areas, root rot has become a major disease, often occurring in conjunction with tobacco black shank, resulting in tobacco losses, especially in continuously cropped fields and under hot and humid conditions. Control methods still have limitations. For example, while traditional chemical fungicides have the advantages of low cost and fewer limitations, the large-scale use of chemical pesticides leads to pesticide residue problems, affecting not only the quality and safety of tobacco leaves but also threatening human health. Furthermore, long-term and excessive use of chemical pesticides increases the resistance of pathogens and pests; broad-spectrum chemical pesticides can easily inadvertently kill natural enemies of pests, resulting in increasingly poor efficacy, and also causing a series of environmental pollution problems. Exogenous biocontrol bacteria, due to their short shelf life and high cost, are still difficult to control this disease in the short term. Therefore, it is imperative to find a safer and more effective production management measure to reduce soil-borne diseases in tobacco plants. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for intercropping flue-cured tobacco with scallions and its application in reducing root rot in tobacco fields. This method can not only change the current situation of continuous flue-cured tobacco cropping in tobacco-growing areas and improve the soil microenvironment for tobacco plant growth, but also avoid the problem of increased soil-borne diseases caused by long-term continuous flue-cured tobacco cropping.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for intercropping flue-cured tobacco with scallions includes the following steps:

[0007] (1) Transplanting of tobacco plants: Transplanting of flue-cured tobacco plants shall be carried out in mid-to-late April;

[0008] (2) Intercropping with scallions: Intercrop scallions next to the tobacco plants within 0-7 days after transplanting;

[0009] (3) Harvesting of scallions: Harvest regularly;

[0010] (4) The lower, middle and upper tobacco leaves are harvested in June, July and August-September respectively.

[0011] Furthermore,

[0012] In step (2), a row of tobacco plants is planted in the middle of each tobacco ridge, and a row of scallions is planted parallel to each other on both sides of the tobacco plants.

[0013] In step (2), tobacco transplanting is carried out in mid-to-late April, with a planting density of 1100-1200 plants / mu, that is, the row spacing of tobacco plants is 110-130cm and the plant spacing is 50-55cm.

[0014] In step (2), the spacing between scallion plants is 8-12cm; the row spacing between scallion plants and tobacco plants is 13-17cm.

[0015] In step (2), scallions are not interplanted between tobacco plants in each row.

[0016] Furthermore,

[0017] The method described in step (1) is to prepare the tobacco field before transplanting the tobacco plants: after applying base fertilizer to the tobacco field in late March, the tobacco field is ridged, and finally a layer of biodegradable mulch is covered on the soil surface.

[0018] Step (3) Harvest the scallions for the first time when they reach a height of 15-20 cm, and then harvest them every 22-28 days thereafter.

[0019] In late October, the tobacco stalks are removed, and the land is immediately prepared and green manure is sown. In mid-to-late March of the following year, the green manure plants are turned into the soil to decompose. In April, the flue-cured tobacco is transplanted, and the cycle is repeated.

[0020] The present invention also provides the application of the method in alleviating root rot in tobacco fields.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) It significantly reduced the incidence of root rot in flue-cured tobacco;

[0023] (2) Reduce disease by altering the nutrient composition of the soil around the tobacco plants;

[0024] (3) Reduce disease by increasing the diversity and optimizing the structure of the fungal community in the rhizosphere soil of tobacco plants;

[0025] (4) Reduce disease by collecting antibacterial metabolites from the rhizosphere soil of tobacco plants.

[0026] (5) Compared with the monoculture of flue-cured tobacco, intercropping flue-cured tobacco with scallions can increase the diversity of the tobacco field system. The interspecific interaction between tobacco plants and intercropped scallions can activate soil nutrients, regulate the community structure of soil microorganisms in the rhizosphere of crops, and improve the productivity and immunity of tobacco plants by inhibiting pathogenic microorganisms. Moreover, the stability and dominance of the rhizosphere microbial community are stronger, which is an effective means to alleviate the continuous cropping obstacles of tobacco plants and improve the system's stress resistance. Attached Figure Description

[0027] Figure 1 This illustrates the effects of different intercropping plants in flue-cured tobacco on the incidence and pathogen quantity of root rot in tobacco fields, as shown in Example 1.

[0028] Figure 1 A: Incidence rate; Figure 1 B: Number of pathogens; Figure 1 C; Correlation analysis between incidence rate and pathogen quantity.

[0029] Figure 2 This illustrates the effects of different intercropping plants on soil nutrients in tobacco fields in Example 1.

[0030] Figure 2 A: Organic carbon content; Figure 2 B: Ammonium nitrogen content; Figure 2 C: Nitrate nitrogen content; Figure 2 D: Available phosphorus content; Figure 2 E: Correlation analysis between organic carbon, ammonium nitrogen, nitrate nitrogen, available phosphorus and the incidence of root rot and the number of pathogens.

[0031] Figure 3 This illustrates the effects of different intercropping plants in flue-cured tobacco on the diversity of rhizosphere soil fungal communities in Example 1.

[0032] Figure 3 A: Shannon abundance; Figure 3 B: Chao abundance; Figure 3 C: Ace abundance; Figure 3 D: Correlation analysis of Shannon, Chao, Ace with root rot incidence and pathogen abundance.

[0033] Figure 4 This illustrates the effects of different intercropping plants on the composition and function of the rhizosphere soil fungal community in tobacco plants, as described in Example 1.

[0034] Figure 4 A: Relative abundance of dominant fungi; Figure 4 B: Correlation analysis between dominant fungi and the incidence and number of root rot pathogens; Figure 4 C: Functions of fungi.

[0035] Figure 5This illustrates the effects of different intercropping plants on rhizosphere soil metabolites in flue-cured tobacco in Example 1.

[0036] Figure 5 A: Relative content of major metabolites; Figure 5 B: Correlation analysis between major metabolites and the incidence of root rot and the number of pathogens.

[0037] Figure 6 This illustrates the effect of planting scallions at different times on the incidence and pathogen count of root rot in tobacco fields, as shown in Example 2.

[0038] Figure 6 A: Incidence rate; Figure 6 B: Number of pathogens.

[0039] Figure 7 This study examines the effects of planting scallions at different times on soil nutrients in tobacco fields during the tobacco curing process in Example 2.

[0040] Figure 8 This study examines the effects of different planting times of scallions on the composition and function of the rhizosphere soil fungal community in flue-cured tobacco plants, as described in Example 2.

[0041] Figure 8 A: Relative abundance of dominant fungi; Figure 8 B: Functions of fungi.

[0042] Figure 9 This study examines the effects of different timing of scallion cultivation on rhizosphere soil metabolites in flue-cured tobacco plants, as described in Example 2.

[0043] Figure 10 This study investigated the effects of different densities of scallions intercropped with flue-cured tobacco on the incidence of root rot and the number of pathogens in tobacco fields, as described in Example 3.

[0044] Figure 10 A: Incidence rate; Figure 10 B: Number of pathogens.

[0045] Figure 11 This study examines the effects of different densities of scallions intercropped with flue-cured tobacco on soil nutrients in tobacco fields, as described in Example 3.

[0046] Figure 12 This study examines the effects of different densities of scallion intercropping on flue-cured tobacco on the rhizosphere soil fungal community and its function in Example 3.

[0047] Figure 12 A: Relative abundance of Ascomycota; Figure 12 B: Relative abundance of Basidiomycota; Figure 12 C: Relative abundance of Chytridiomycota; Figure 12 D: Relative abundance of Mortierellomycota; Figure 12 E: Functions of fungi.

[0048] Figure 13 The effect of different densities of scallions intercropped with flue-cured tobacco on the microclimate of the tobacco field in Example 3;

[0049] Figure 13 A: Temperature; Figure 13 B: Humidity; Figure 13 C: CO2.

[0050] Figure 14 This refers to the location of the scallions used as an intercropping in Example 4;

[0051] Figure 15 This example illustrates the effect of the location of scallion intercropping with flue-cured tobacco on the incidence and pathogen quantity of root rot in tobacco fields.

[0052] Figure 15 A: Incidence rate; Figure 15 B: Number of pathogens.

[0053] Figure 16 This study examines the impact of the location of intercropping scallions with flue-cured tobacco on the economic benefits of tobacco fields in Example 4. Detailed Implementation

[0054] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, the following embodiments are intended to further illustrate the present invention, rather than to limit it.

[0055] Example 1: The effects of intercropping different plants in flue-cured tobacco on root rot disease in tobacco fields

[0056] Intercropping scallions (T1) and amaranth (T2) in flue-cured tobacco fields was used as treatments, with monoculture tobacco as the control (CK). The effects of these three treatments on the occurrence of root rot in tobacco fields were compared. The planting process for monoculture tobacco was as follows: applying basal fertilizer, ridging, and mulching the tobacco field around late March → transplanting tobacco plants in mid-to-late April → harvesting the lower, middle, and upper tobacco leaves in June, July, and August-September, respectively. The planting process for intercropping tobacco was as follows: applying basal fertilizer, ridging, and mulching the tobacco field around late March → transplanting tobacco plants in mid-to-late April → intercropping amaranth or scallions within 0-7 days after transplanting → continuously harvesting amaranth or scallions from May to October → harvesting the lower, middle, and upper tobacco leaves in June, July, and August-September, respectively. In late October, the tobacco stalks are removed, and the land is immediately prepared and green manure is sown. In mid-to-late March of the following year, the green manure plants are turned into the soil to decompose. In April, the flue-cured tobacco is transplanted, and the cycle is repeated.

[0057] Plant a row of tobacco plants in the middle of each tobacco ridge, and plant a row of amaranth or scallions on each side of the tobacco plants in parallel rows.

[0058] Tobacco transplanting is carried out in mid-to-late April, with a planting density of 1100-1200 plants per mu (approximately 667 square meters), which means the row spacing is 120 cm and the plant spacing is 50 cm.

[0059] The spacing between amaranth plants is 12.5cm; the row spacing between amaranth and tobacco plants is 15cm.

[0060] The spacing between scallion plants is 10cm; the row spacing between scallion and tobacco plants is 15cm.

[0061] Amaranth or scallions should not be interplanted between tobacco plants in each row.

[0062] I. Impact on the incidence and pathogen quantity of root rot in tobacco fields

[0063] Compared with the control (CK) treatment, the incidence of root rot and the number of pathogens decreased by 31.96% and 59.83% respectively in the T1 treatment, while the incidence of root rot and the number of pathogens decreased by 15.69% and 27.56% respectively in the T2 treatment. Figure 1 A / B correlation analysis showed that the correlation coefficient between the number of pathogens and the incidence of root rot reached 0.90. Figure 1 C) indicates that the incidence of root rot increases with the increase in the number of pathogens.

[0064] The incidence rate (%) was measured in July, the peak of the disease outbreak. The incidence rate (%) was calculated as (number of diseased plants / total number of plants surveyed) × 100%. The pathogen count was determined using a molecular biology quantitative method (extracting pathogen DNA, amplifying specific gene fragments using real-time quantitative PCR (qPCR), and calculating the initial copy number of pathogen DNA based on the Ct value of the standard to achieve highly sensitive quantification).

[0065] The results above indicate that the T1 treatment (intercropping scallions with flue-cured tobacco) was the most effective in reducing root rot disease in tobacco plants.

[0066] II. Impact on the rhizosphere soil of tobacco plants

[0067] 1. Effects on soil nutrients in the rhizosphere of tobacco plants: Measurements were taken in July during the peak of the disease outbreak, using mass spectrometry: the nutrient content in the soil was analyzed by measuring the mass-to-charge ratio of ions in the soil.

[0068] Compared with the control (CK) treatment, the organic carbon in the T1 and T2 treatments increased by 34.40% and 17.20%, respectively; ammonium nitrogen decreased by 28.87% and 11.97%, respectively; nitrate nitrogen increased by 84.62% and 23.08%, respectively; and available phosphorus increased by 20.28% and 12.37%, respectively. Figure 2 AD).

[0069] Furthermore, the contents of organic carbon, available phosphorus, and nitrate nitrogen were all negatively correlated with the incidence of root rot and the number of pathogens, while ammonium nitrogen showed a significant positive correlation. Figure 2 E) indicates that nitrogen form transformation under the flue-cured tobacco intercropping model may inhibit pathogens through nitrogen source competition (i.e., reducing the ammonium nitrogen content and increasing the nitrate nitrogen content in the soil), thereby inhibiting the reproduction of root rot pathogens to a certain extent and ultimately reducing the occurrence of the disease.

[0070] 2. Impact on the fungal community of tobacco rhizosphere soil: Measurements were taken in July during the peak of disease incidence using metagenomic methods.

[0071] Effects on fungal community diversity: Intercropping with flue-cured tobacco significantly increased the diversity of soil fungi in tobacco plants, and the fungal diversity increased with the number of years of intercropping. Compared with the control treatment, the Shannon, Chao, and Ace diversity indices of the T1 and T2 treatments increased by 10.11% and 2.25%, 6.70% and 0.53%, and 20.86% and 4.91%, respectively. Figure 3 Furthermore, the diversity index of the fungal community showed significant and highly significant positive correlations with both disease incidence and pathogen abundance. Figure 3 (D) This indicates that the diversity of fungal communities is closely related to disease resistance; the higher the community diversity, the stronger the tobacco plant's ability to resist disease invasion.

[0072] Impact on fungal community composition: Metagenomic testing results showed that the dominant fungal communities in all three treatments were Ascomycota, Basidiomycota, Chytridiomycota, and Mortierellomycota. Figure 4 A). Compared with the CK treatment, the abundance of *Chytridiomycota* decreased by 65.38% and 26.92% in the T1 and T2 treatments, respectively, while the abundance of *Ascomycota*, *Basidiomycota*, and *Mortierellomycota* increased by 47.62% and 23.81%, 70.59% and 52.94%, and 68.75% and 31.25%, respectively. Further Pearson correlation analysis showed that at the phylum level, *Chytridiomycota* and *Ascomycota*, *Basidiomycota*, and *Mortierellomycota* were significantly negatively and positively correlated with root rot incidence and pathogen abundance, respectively. Figure 4B). Further analysis revealed that the main functions of the fungi *Ascomycota*, *Basidiomycota*, and *Mortierellomycota* are: 1) improving soil structure by regulating soil nutrient cycling and organic carbon decomposition; 2) helping plants absorb nutrients such as nitrogen and phosphorus, enhancing water use efficiency, and thus improving stress resistance; 3) inhibiting pathogens and reducing soil-borne diseases by competing for nutrients and producing antimicrobial substances (such as lipopeptide antibiotics); and 4) decomposing organic matter and releasing nutrients for other organisms. However, excessive proliferation of *Chytridiomycota* can lead to plant diseases.

[0073] Effects on fungal community function: The fungal community of each treatment was at the Plant_Pathogen-Soil_Saprotroph-Wood_Saprotroph functional layer with an abundance greater than 10% in the secondary functional layer. Figure 4 C), the abundance of the three treatments showed that T1 (0.52) > T2 (0.38) > CK (0.34). The main function of this functional layer is that Soil_Saprotroph promotes nutrient cycling by decomposing organic matter and converting complex organic matter into inorganic nutrients for plant absorption; and inhibits pathogens and reduces disease occurrence by competing for resources or producing antimicrobial substances. Wood_Saprotroph reduces the relative abundance of soil pathogens by changing the composition of the fungal community, promoting the formation of beneficial bacteria, and ultimately reducing the incidence of soil-borne diseases caused by Plant_Pathogen (including root rot).

[0074] The results above indicate that intercropping with flue-cured tobacco improved the diversity of the fungal community, optimized the composition of the fungal community, and enhanced the stress resistance of the fungal community, with the T1 treatment (intercropping flue-cured tobacco with scallions) showing the best effect.

[0075] 3. Effects on rhizosphere soil metabolites of tobacco plants: Measurements were taken in July during the peak of the disease outbreak, using [method / method / approach]. LC-MS / GC-MS - Untargeted Metabolomics .

[0076] Compared with the control (CK), the levels of Lipopeptide, Isoquinoline alkaloids, Naringenin, and Phenolic acids increased by 11.74% and 1.23%, 31.05% and 13.36%, 39.41% and 23.23%, and 29.95% and 15.91% in the T1 and T2 treatments, respectively, while the levels of Aminopenicillanic acid, Ylbenzenesulfonic acid, and Garcinia acid decreased by 22.58% and 14.26%, 29.27% ​​and 22.33%, and 32.07% and 12.74%, respectively. Figure 5 A). Among them, the first four metabolites were significantly negatively correlated with the incidence and pathogen quantity of root rot, while the latter three metabolites were positively correlated. Figure 5 B).

[0077] The study further revealed that the first four metabolites all originated from the phenylpropane metabolic pathway, and the compounds produced by this pathway possess antioxidant, defense, and signal transduction activities in plants. These metabolic pathways are interconnected and work together to maintain metabolic homeostasis and physiological processes within organisms, thereby significantly affecting the growth and metabolism of pathogens. The increase in the first four metabolites was greater in the T1 treatment than in the T2 treatment.

[0078] In conclusion, this invention suggests that intercropping scallions with flue-cured tobacco is the most effective way to reduce root rot disease.

[0079] Example 2: The effect of intercropping scallions at different times on root rot disease in tobacco fields

[0080] Scallions were intercropped within <7 days (T1, specifically day 3) and >8 days (T2, specifically day 10) after tobacco transplanting to compare their effect on reducing root rot disease and to explore the mechanism of the difference in effect. All other conditions were the same as in Example 1.

[0081] I. Impact on the incidence and pathogen quantity of root rot in tobacco fields

[0082] Compared with the T1 treatment, the T2 treatment increased the incidence of root rot and the number of pathogens by 26.71% and 51.79%, respectively. Figure 6 This indicates that the T1 treatment (intercropping with scallions within 0-7 days after tobacco transplanting) is the most effective way to reduce root rot in tobacco plants.

[0083] II. Impact on the rhizosphere soil of tobacco plants

[0084] The results of Example 1 show that the soil nutrients, fungal community composition and metabolites in the rhizosphere of tobacco plants under the intercropping pattern are highly correlated with the incidence of root rot in tobacco plants. Therefore, this invention further studies the effects of intercropping scallions at different times on the three factors in order to reveal the mechanism by which it reduces the differences in root rot in tobacco plants.

[0085] Effects on nutrients: Compared with treatment T1, treatment T2 reduced organic carbon, nitrate nitrogen, and available phosphorus by 24.61%, 28.88%, and 2.57%, respectively, while increasing ammonium nitrogen by 18.68%. Figure 7 ).

[0086] Effects on fungal community composition: Although the dominant fungi in the T1 and T2 treatments were consistent at the phylum level ( Figure 8A), but the difference in abundance was significant. Compared with the T2 treatment, the T1 treatment increased the abundance of Ascomycota, Basidiomycota, and Mortierellomycota by 21.43%, 11.11%, and 22.22%, respectively, while reducing Chytridiomycota by 72.78%. Figure 8 A)

[0087] Impact on fungal community function: The abundance of fungal communities in each treatment was greater than 10% in the Plant_Pathogen-Soil_Saprotroph-Wood_Saprotroph functional layer at the secondary functional level. The abundance of the three treatments showed a trend of T1 (0.16) > T2 (0.10). Figure 8 B)

[0088] Effects on tobacco rhizosphere soil metabolites: Compared with T1 treatment, T2 treatment showed a 5.68% decrease in Lipopeptide, 13.52% decrease in Isoquinoline alkaloids, 11.60% decrease in Naringenin, and 10.80% decrease in Phenolic acids, while an 11.04% increase in Aminopenicillanic acid, Ylbenzenesulfonic acid, and Garcinia acid, respectively. Figure 9 This indicates that the T1 treatment had a higher content of metabolites in the phenylpropanoid metabolic pathway with stress resistance than the T2 treatment.

[0089] In summary, this invention suggests that planting scallions within 0-7 days (T1) after tobacco transplanting is the most effective way to reduce root rot disease in the intercropping of flue-cured tobacco with scallions. This may be because the earlier the scallions are planted, the earlier the microorganisms and metabolites released by their roots act on the soil, thus degrading the number of root rot pathogens very early.

[0090] Example 3: The effect of intercropping scallions at different densities (plant spacing) with flue-cured tobacco on root rot disease in tobacco fields.

[0091] On the third day after the tobacco plants were transplanted, scallions were intercropped with a row spacing of 120cm, but the scallion plant spacing was set to be <8cm (T1, specifically 7cm), 8-12cm (T2, specifically 10cm), and >13cm (T3, specifically 14cm) to compare their effects on reducing root rot disease and to explore the mechanism of the difference in effects. All other conditions were the same as in Example 1.

[0092] I. Impact on the incidence and pathogen quantity of root rot in tobacco fields

[0093] The three treatments showed a trend in morbidity rate: T1 (20.8%) > T3 (18.6%) > T2 (16.2%). In terms of pathogen count, T1 showed a trend of [missing data - likely a number of treatments]. 6 cfu / g)>T3(0.47×10 6 cfu / g)>T2(0.36×10 6 The trend of CFU / g showed that the differences between T1 and T2 and T3 were significant, while the differences between the latter two were not significant. Figure 10 ).

[0094] The results above indicate that the T2 treatment is the most effective in reducing the incidence of root rot in tobacco plants and the number of pathogens.

[0095] II. Effects on the rhizosphere soil of tobacco plants on nutrients: In terms of organic carbon, nitrate nitrogen, and available phosphorus, all three treatments showed a trend of T2>T3>T1, while in ammonium nitrogen, the trend was T1>T2>T3. The differences between T1 and T2 and T3 were significant, while the differences between the latter two were not significant. Figure 11 The reason for these trends is speculated to be that scallions also need to absorb nutrients for growth. When the intercropping spacing is too small (high planting density), they absorb more nutrients from the soil, and the competition with tobacco plants becomes more intense, resulting in a decrease in organic carbon, nitrate nitrogen, and available phosphorus in the rhizosphere soil of tobacco plants. Similarly, because scallions with higher planting density release more harmful substances (ammonium nitrogen), the root rot disease becomes more severe. This result is consistent with the conclusion in Example 1 that "the content of organic carbon, available phosphorus, and nitrate nitrogen is negatively correlated with the incidence of root rot disease and the number of pathogens, while ammonium nitrogen is the opposite."

[0096] Effects on fungal community composition: In terms of relative abundance of Ascomycota, Basidiomycota, and Mortierellomycota, all three treatments showed a trend of T2>T3>T1, but in terms of relative abundance of Chytridiomycota, all showed a trend of T1>T3>T2. Figure 12 Similarly, the difference between the T1 treatment and the T2 and T3 treatments was significant, while the difference between the latter two was not significant.

[0097] Effects on fungal community function: The abundance of fungal communities in each treatment was greater than 10% in the Plant_Pathogen-Soil_Saprotroph-Wood_Saprotroph functional layer in the secondary functional layer. The abundance of the three treatments showed the following order: T2 (0.41) > T3 (0.28) > T1 (0.22).

[0098] The above results indicate that the T2 treatment has the best effect in reducing root rot disease in tobacco plants, which is closely related to the relative abundance of nutrients in the rhizosphere soil, the composition of the fungal community, and the function of the fungal community.

[0099] III. Impact on the microclimate of tobacco fields

[0100] In terms of temperature, humidity, and CO2 concentration in the tobacco field, the three treatments showed a significant correlation between T1 and T2 and T3, with significant differences between T1 and both T2 and T3, while the differences between the latter two were not significant. Figure 13 This indicates that the smaller the plant spacing of intercropped scallions (the denser the scallions), the higher the temperature and CO2 concentration in the tobacco field, which is not conducive to the circulation of O2. This results in slow water evaporation and excessive humidity in the tobacco field, ultimately increasing the incidence of root rot.

[0101] In conclusion, this invention suggests that the T2 treatment (with an intercropping of scallions at a spacing of 8-12 cm) is the most effective in reducing root rot disease.

[0102] Example 4: The effect of intercropping scallions with flue-cured tobacco on root rot disease in tobacco fields

[0103] On the third day after transplanting the tobacco plants, scallions were planted between them. The row spacing was 120cm between the tobacco plants and the scallion spacing was 10cm. However, two planting positions were set up for the scallions (the first is the planting method of this invention, in which two rows of scallions are planted between each row of tobacco plants, T1 treatment; the second is to plant scallions between two tobacco plants, T2 treatment). Figure 14 To compare their effects on reducing root rot and to explore the mechanisms of the differences in effects, the remaining conditions were the same as in Example 1.

[0104] I. Impact on the incidence and pathogen quantity of root rot in tobacco fields

[0105] The two treatments showed a clear trend in morbidity and pathogen count: T2 (17.84%) > T1 (13.56%) and T2 (1.15 × 10⁻⁶%) > T1 (13.56%). 6 cfu / g)>T1(0.66×10 6 The trend of CFU / G ( Figure 15 This indicates that treatment T1 was more effective than treatment T2 in reducing root rot in tobacco plants.

[0106] II. Impact on the economic benefits of tobacco fields

[0107] Compared to single-crop tobacco processing, the costs of T1 and T2 processing increased by RMB 133 and RMB 107 respectively, while the profits (tobacco + scallions) increased by RMB 301 and RMB 243 respectively, and the net profits increased by RMB 168 and RMB 136 respectively. Figure 16 ).

[0108] In conclusion, this invention suggests that the T1 treatment is superior to the T2 treatment in reducing root rot disease and improving the economic benefits of tobacco fields.

Claims

1. A method for growing flue-cured tobacco intercropped with Allium fistulosum, characterized by, The method comprises the following steps: (1) transplanting tobacco plants: transplanting tobacco plants in the middle or late April; (2) interplanting chives: interplanting chives beside the tobacco plants within 0-7 days after the tobacco plants are transplanted; (3) harvesting chives: harvesting chives regularly; (4) harvesting lower, middle and upper tobacco leaves in June, July and August-September respectively.

2. The method of claim 1, wherein, In step (2), one row of tobacco plants is planted in the middle of each tobacco ridge, and one row of chives is interplanted parallel to the two sides of the tobacco plants.

3. The method of claim 2, wherein, In step (2), the tobacco plants are transplanted in the middle or late April, and the planting density is 1100-1200 plants per mu, i.e., the row spacing of the tobacco plants is 110-130 cm, and the plant spacing is 50-55 cm.

4. The method of claim 2, wherein, In step (2), the plant spacing of the chives is 8-12 cm, and the row spacing of the chives and the tobacco plants is 13-17 cm.

5. The method of claim 2, wherein, In step (2), no chives are interplanted between the tobacco plants in each row of tobacco plants.

6. The method of claim 1, wherein, Before step (1), the preparation of the tobacco field: after applying base fertilizer in the tobacco field in the late March, the tobacco field is ridged, and finally a layer of degradable mulch is covered on the surface of the soil.

7. The method of claim 1, wherein, In step (3), the first harvest is performed when the height of the chives reaches 15-20 cm, and then the chives are harvested every 22-28 days.

8. The method of claim 1, wherein, In the late October, the tobacco stalks are removed, and immediately the soil is prepared for sowing green manure. In the middle or late March of the next year, the green manure plants are ploughed into the soil for decomposition, and in April, the tobacco plants are transplanted, and the cycle is repeated.

9. Use of the method of any one of claims 1-8 in reducing tobacco field root rot.

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