A method for improving tobacco resistance to aphids

Abstract

The application discloses a method for improving the resistance of tobacco to aphids, and belongs to the field of agricultural technology. It is found that soil selenium application can improve the resistance of tobacco to aphids, and sodium selenite can be used to improve the resistance of tobacco to aphids and used for preparing a preparation for improving the resistance of tobacco to aphids. The method for improving the resistance of tobacco to aphids comprises the step of applying a preparation containing exogenous selenium to soil in which tobacco is planted. The method can enhance the resistance of tobacco to aphids by soil selenium application, has low cost, is green and environment-friendly compared with chemical pesticide control, and has important theoretical and practical significance for developing a new aphid control strategy.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture, and in particular relates to application of sodium selenite in improving tobacco resistance to aphids, and more particularly relates to a method for improving tobacco resistance to aphids. Background Art

[0002] Tobacco aphids, also known as peach aphids, belong to the Arthropoda, Insecta, Hemiptera, Aphididae. They are a major pest of flue-cured tobacco, severely impacting its yield and quality. Adults and nymphs directly feed on tobacco plant sap, affecting its growth and development, thereby reducing tobacco yield and quality. Furthermore, the honeydew they secrete can severely contaminate tobacco leaves, causing them to blacken, become brittle, and even rot. This can lead to sooty mold disease, which indirectly harms tobacco leaves.

[0003] Selenium is an essential trace element for human and animal life and is also beneficial for plant growth. Adequate amounts of selenium can promote plant growth and increase yield. A moderate amount of selenium is beneficial for tobacco growth. It promotes seed germination and enhances root vitality; increases protein and potassium content in tobacco leaves while reducing nicotine content; and enhances chlorophyll content and alters the aroma of tobacco leaves. Selenium is a stress-resistant element for plants and has been shown to protect against a variety of environmental stresses. It maintains the stability of plant cell membranes, enhances cell viability, and induces the synthesis of phytoalexins.

[0004] Existing aphid control measures include agricultural control (selecting appropriate tillage and fertilization patterns, and adjusting sowing times appropriately), physical control (setting up yellow traps to attract aphids, adjusting the control based on temperature, humidity, and light), biological control (natural enemies, insect hormones, microbial pesticides, botanical pesticides, etc.), and chemical control (chemical pesticides such as carbamates and organophosphates). However, agricultural and physical control measures consume significant manpower and financial resources, while chemical control can cause pesticide residues on leaves, pollute the environment, and promote pesticide resistance in tobacco. Therefore, finding effective, ecologically friendly, and environmentally friendly pest control measures is crucial for tobacco pest control. Summary of the Invention

[0005] In order to alleviate the occurrence of tobacco aphids and improve the economic benefits of tobacco, the present invention aims to provide a method for improving tobacco aphid resistance by using sodium selenite.

[0006] In the present invention, potted plant experiments confirmed that applying selenium to the soil can improve the growth and development of tobacco seedlings and their ability to resist attack by the piercing-sucking insect, tobacco aphids. It was also confirmed that different concentrations of sodium selenite inhibited the survival rate of tobacco aphids on tobacco plants to varying degrees. When the exogenous sodium selenite concentration was less than 2 mg / kg, the survival rate of tobacco aphids decreased as the exogenous sodium selenite concentration increased. At an exogenous sodium selenite concentration of 2 mg / kg, the survival rate of tobacco aphids reached its lowest level.

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] The invention relates to the application of exogenous selenium in improving tobacco's resistance to aphids, and the application is achieved by applying a preparation containing exogenous selenium to the soil where tobacco is planted.

[0009] Application of exogenous selenium in the preparation of preparations for improving tobacco resistance to aphids.

[0010] A method for improving tobacco's resistance to aphids comprises the step of applying a preparation containing exogenous selenium to tobacco-growing soil.

[0011] In some embodiments, the exogenous selenium is tetravalent selenium (Se 4+ ); further, the exogenous selenium is sodium selenite.

[0012] In some embodiments, the formulation is a fertilizer or a growth regulator.

[0013] In some embodiments, when the exogenous selenium is sodium selenite, in the above application or method, the concentration of sodium selenite is 2 mg / kg.

[0014] The present invention has the following advantages and beneficial effects:

[0015] (1) Soil selenium application can promote the growth and development of tobacco seedlings, increase the density of glandular hairs on tobacco leaves, and promote the physiological and biochemical activities of tobacco plants such as the content of defense enzymes and photosynthesis, thereby enhancing the resistance of tobacco plants to cope with insect pests and has no adverse effect on tobacco yield.

[0016] (2) The present invention can effectively improve the aphid resistance of plants. The aphid resistance of tobacco can be enhanced by applying selenium to the soil. The cost is low and it is green and environmentally friendly compared to chemical pesticide control. It has important theoretical and practical significance for the development of new aphid control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Figure 2 shows the growth of aphids on Se 2-treated and CK tobacco leaves 20 days after aphid inoculation.

[0018] Figure 2Effects of selenium on the morphology of tobacco glandular hairs. A: Control group glandular hairs × 100, B: Se 0.5 treated glandular hairs × 100, C: Se 1 treated glandular hairs × 100, D: Se 2 treated glandular hairs × 100, E: Se 4 treated glandular hairs × 100.

[0019] Figure 3 The effect of selenium on the density of tobacco glandular hairs.

[0020] Figure 4 The effect of selenium on tobacco defense enzymes: A: polyphenol oxidase PPO, B: phenylalanine ammonia lyase PAL, C: lipoxygenase LOX, D: peroxidase POD. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and comprehensively described below in conjunction with the embodiments of the present invention, and it is not to be understood as a limitation of the present invention.

[0022] Unless otherwise specified, the technical means and scientific terms used in the examples have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs, and are conventional means known to those skilled in the art. The experimental methods in the following examples, unless otherwise specified, are all conventional methods. The instruments and equipment used in the following examples, unless otherwise specified, are all conventional laboratory instruments and equipment; the experimental materials used in the following examples, unless otherwise specified, were all purchased from conventional biochemical reagent stores.

[0023] Example 1:

[0024] Sodium selenite was used as a selenium source (solid powder purchased from Zhengzhou Aikemu Chemical Co., Ltd., 99% analytical grade). Sodium selenite solutions at concentrations of 0, 0.5, 1, 2, and 4 mg / kg were prepared with water and applied to the soil. After a week of stagnation, tobacco seedlings were transplanted. Specifically, five different selenium concentrations were applied to the soil: CK: 0 mg / kg (control), Se 0.5: 0.5 mg / kg, Se 1: 1 mg / kg, Se 2: 2 mg / kg, and Se 4: 4 mg / kg. Each treatment was replicated five times, with one tobacco seedling per pot, for a total of 25 pots. Soil culture boxes were 7 x 7 cm, each containing 200 g of soil.

[0025] Tobacco seed cultivation: The experiment was conducted at the Tobacco Quality Ecology Laboratory of the Tobacco College of Henan Agricultural University. The tobacco variety tested was K326. Plump, uniform tobacco seeds were first disinfected with a 10% sodium hypochlorite solution and soaked at room temperature for 3-5 minutes. The sodium hypochlorite solution was then discarded. The seeds were then disinfected with 70% anhydrous ethanol and soaked at room temperature for 30 seconds. The seeds were then rinsed 3-4 times with sterile water, followed by 5-6 rinses with ultrapure water and soaked for 8 hours. The seeds were then evenly distributed on a sponge and placed in an artificial climate incubator for germination.

[0026] Tobacco seedling cultivation: Soil culture was used for seedling cultivation. In the early stages of the experiment, seedling trays and I-shaped sponges were used as the medium. After the tobacco seeds germinated to three leaves in an artificial climate incubator, seedlings with consistent growth were selected and moved with tweezers to vermiculite for growth. When the tobacco seedlings reached the four-leaf stage, they were moved to soil culture boxes supplemented with exogenous sodium selenite for growth. Treatment began after the seedlings had reached six leaves and one heart.

[0027] The entire culture period was carried out in an artificial incubator, and the incubator environment was maintained at: 28℃±2℃ / 18℃±2℃ day and night, 14 / 10h photoperiod, 70% relative humidity, and 440μmol·m -2 ·s -1 .

[0028] Example 2:

[0029] Soil selenium application reduced the survival rate of the piercing-sucking insect Myzus persicae (P. mesydis) on tobacco:

[0030] Tobacco seedlings were treated when they reached six leaves and one heart in soil culture boxes. Seedlings with good and consistent growth were selected and artificially inoculated with aphids on the second leaf of each tobacco plant at a density of 10 aphids per plant. After inoculation, the seedlings were centrally isolated using 100-mesh insect-proof netting. The number of aphids was counted on the 20th day after inoculation (Table 1).

[0031] The results showed that the survival rates of tobacco aphids on tobacco leaves treated with Se 0.5, Se 1, Se 2, and Se 4 were reduced by 49.5%, 58.4%, 64.4%, and 31.7%, respectively, compared with the control group. Among them, when the exogenous sodium selenite concentration was 2 mg / kg, the number of tobacco aphids on tobacco plants was the least and the survival rate of tobacco aphids was the lowest.

[0032] Table 1 Effects of selenium on the number of aphids on tobacco leaves

[0033]

[0034] Note: Different lowercase letters indicate significant differences at the p<0.05 level.

[0035] Among them, the morphology of tobacco leaves treated with Se 2 20 days after inoculation with aphids is shown in Figure 1, it can be seen that the number of aphids on tobacco leaves under Se2 treatment was significantly lower than that under CK treatment.

[0036] Example 3:

[0037] Effects of soil selenium application on the morphology and density of tobacco glandular trichomes:

[0038] Thirty days after artificial inoculation with tobacco aphids, tobacco plants of uniform growth were selected. Top leaves approximately 10 cm long were selected and stained in a 0.2% (by volume) aqueous solution of rhodamine B for 30 minutes. The leaves were then rinsed three times with distilled water to remove any unbound dye, and the surface moisture was blotted dry. Leaves approximately 5 mm × 8 mm in the middle of the leaf were excised, avoiding the veins. The morphology and number of epidermal trichomes were observed under a super-depth microscope (VHX-5000, Keyence Corporation, Japan). Trichoderma density was counted and analyzed in randomly selected fields.

[0039] The morphological observation results of glandular hairs on the leaf epidermis of K326 are shown in Figure 2 K326 has three types of epidermal hairs: long-stalked glandular hairs, short-stalked glandular hairs, and a small number of guard hairs. The number of long-stalked and short-stalked glandular hairs on the same leaf epidermis is similar, and the glandular heads are wrapped in secretions and have a spherical or teardrop-shaped appearance. Compared to the control, the number of glandular hairs on leaves treated with Se increased. Se2-treated tobacco leaves had straight, plump, and complete glandular hairs, while the control leaves had poorly developed glandular hairs and showed signs of bending.

[0040] The results of counting the density of glandular hairs on the leaves under a microscope are as follows Figure 3 As shown in the results, the density of long-stalked glandular hairs in the Se treatments increased by 73.3%, 80%, 126.7%, and 13.3%, respectively, compared with the control. The density of short-stalked glandular hairs in the order of Se2 > Se1 > Se0.5 > CK > Se4 was significantly lower in the Se4 treatment than in the control. The density of all three types of glandular hairs in the Se2 treatment was significantly higher than in the control and other treatments. These results indicate that selenium treatment within an appropriate concentration range can increase the density of tobacco leaf glandular hairs and improve the leaf defense capacity.

[0041] Example 4:

[0042] Effects of soil selenium application on tobacco photosynthesis:

[0043] On the 25th day after artificial inoculation with tobacco aphids, tobacco plants with uniform growth were selected and the photosynthetic intensity of the top leaves of tobacco leaves was measured between 10:00 and 12:00 am using a photosynthetic meter model: Hangzhou LS-1020 (Hangzhou Lvbo Instrument Co., Ltd.).

[0044] The photosynthetic parameters of each treatment tobacco leaf were determined as shown in Table 2. Compared with the control group, the net photosynthetic rate of Se-treated leaf was significantly increased, and the transpiration rate and water use efficiency were also increased. The net photosynthetic rate from large to small was Se2>Se1>Se0.5>Se4>CK, wherein the net photosynthetic rate and transpiration rate of Se2 treatment were significantly higher than those of other treatments, and the leaf water use efficiency of Se1 treatment was the highest, which was 37.9% higher than that of the control group. Soil selenium had little effect on the stomatal conductance and intercellular CO2 concentration of tobacco leaves, and there was no significant difference in stomatal conductance and intercellular CO2 concentration among different treatments. The results showed that selenium could improve the photosynthetic performance of tobacco leaves, increase the accumulation of tobacco leaves, and alleviate the decrease of photosynthesis caused by insect pests.

[0045] Table 2 Effect of selenium on photosynthetic parameters of tobacco leaves

[0046]

[0047]

[0048] Note: Different lowercase letters represent significant differences at p<0.05 level.

[0049] Example 5:

[0050] Effect of soil selenium on defense enzymes of tobacco:

[0051] Polyphenol oxidase (PPO) activity determination: 0.005 change in absorbance at 410 nm per mL of reaction system per g of tissue per minute was defined as one enzyme activity unit.

[0052] Phenylalanine ammonia lyase (PAL) activity determination: PAL activity was calculated by measuring the rate of absorbance increase. 0.05 change in absorbance at 290 nm per mL of reaction system per g of tissue per minute was defined as one enzyme activity unit.

[0053] Lipoxygenase (LOX) activity determination: The rate of increase in absorbance at 234 nm was measured, and 0.0006 units of change in absorbance per g of sample per minute in 1 mL system at 25°C was defined as one enzyme activity unit.

[0054] Peroxidase (POD) activity determination: 0.005 change in A470 per mL of reaction system per g of tissue per minute was defined as one enzyme activity unit.

[0055] Effect of different treatments on PPO, PAL, LOX and POD enzyme activities of tobacco Figure 4As shown, the activities of PAL, LOX, and POD under selenium treatment were all higher than those in the control group. PPO activity in the Se4 treatment decreased by 3.7% compared with the control group, while the activities in the other treatments increased by 15.8%, 55.2%, and 64.4%, respectively, with significant differences between Se1 and Se2. PAL activity in the selenium treatment increased by 9.9%, 16.3%, 47.9%, and 3.9%, respectively, compared with the control group, with significant differences between Se2 and the other treatments. LOX activity in the Se4 treatment increased by 1.0% compared with the control group, while LOX activity in the other treatments increased significantly by 20.8%, 54.2%, and 63.4%, respectively. POD activity in the Se0.5 treatment increased by 9.0% compared with the control group, but there was no significant difference. POD activity in the other treatments increased significantly by 64.2%, 102.6%, and 46.3%, respectively, compared with the control group.

[0056] Overall, the activities of PPO, PAL, LOX, and POD in tobacco leaves were the highest under Se2 treatment, indicating that selenium solution within a certain concentration range can increase the enzyme activity of tobacco leaves, thereby enhancing the ability of tobacco leaves to resist pests and alleviate the damage caused by aphids.

[0057] The above embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the following examples based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. The application of exogenous selenium in increasing the density of glandular hairs in tobacco leaves is characterized by: The application is achieved by applying a preparation containing exogenous selenium to the soil where tobacco is grown; the exogenous selenium is sodium selenite, and the concentration of sodium selenite used is 2 mg / kg; and the method of increasing the glandular hair density of tobacco leaves is to increase the glandular hair density of the top leaves of tobacco K326.

2. The use of exogenous selenium in the preparation of a preparation for increasing the density of glandular hairs in tobacco leaves, characterized in that: The exogenous selenium is sodium selenite, and the use concentration of sodium selenite is 2 mg / kg; the method for increasing the density of glandular hairs on tobacco leaves is to increase the density of glandular hairs on the top leaves of tobacco K326.

3. A method for increasing the density of glandular hairs in tobacco leaves, characterized by: The method comprises the steps of applying a preparation containing exogenous selenium to tobacco-growing soil, wherein the exogenous selenium is sodium selenite, and the use concentration of the sodium selenite is 2 mg / kg; and the method of increasing the density of glandular hairs on tobacco leaves is to increase the density of glandular hairs on the top leaves of tobacco K326.

4. The use according to claim 1 or 2 or the method according to claim 3, characterized in that: The preparation is a fertilizer or a growth regulator.

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