Application of a lanthanum-based nanomaterial in controlling rice sheath blight

Abstract

The invention discloses an application of a lanthanum-based nanomaterial in controlling rice sheath blight, belonging to the technical field of pesticides. The invention disperses the lanthanum-based nanomaterial in water to obtain a suspension; then sprays the suspension on rice leaves, and controls rice sheath blight by foliar spraying, and can control the disease index as low as 2.3±1.6, which has very good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of pesticides, and particularly relates to application of a lanthanum-based nanomaterial in controlling rice sheath blight. Background Art

[0002] Globally, crop diseases cause crop yield reductions of up to 20-40% each year, resulting in economic losses of approximately US$40 billion, which seriously hinders the sustainable development of agriculture. At present, in order to reduce the impact of crop diseases and pests, insecticides and fungicides are widely used. However, excessive use of pesticides leads to their large accumulation in the environment, bringing a series of problems to the environment, such as soil degradation, increased pathogen resistance, toxicity to non-target organisms, and threats to human health. Therefore, it is urgent to develop a high-utilization, low-risk, and sustainable alternative to traditional pesticides to efficiently control crop diseases.

[0003] Nano-agriculture technology is a strategic method with broad application prospects for controlling crop diseases, increasing crop yields and global food security. At present, copper-based nanomaterials have shown great potential in crop disease prevention and control, but the long-term use of large amounts of copper-based pesticides leads to the accumulation of Cu in the soil, causing soil pollution, and may even cause target pathogens to acquire drug resistance, reducing the effectiveness of pesticides. Summary of the invention

[0004] In view of the above technical problems and application purposes, the purpose of the present invention is to find out the optimal concentration and the best material of different lanthanum-based nanomaterials (La-based NMs) for controlling rice sheath blight. The technical solution of the present invention is:

[0005] The main contents of the present invention include: (1) preparing different forms and compositions (La 10 Si 6 O 27 Nanorods (NRs), La 10 Si 6 O 27 Nanoparticles (NPs), La(OH) 3 (2) by spraying different concentrations of La 10 Si 6 O 27 NRs were applied to rice to investigate their effectiveness in controlling rice sheath blight; (3) Optimal concentrations of lanthanum-based nanomaterials of different forms and compositions, commercial La 2 O 3 NPs, lanthanum chloride salts with equal amounts, silicate salts with equal amounts, and a traditional pesticide (thiofuran) at agricultural guidance concentrations were applied to rice to investigate their effectiveness in controlling rice sheath blight.

[0006] The present invention provides an application of a lanthanum-based nanomaterial in controlling rice sheath blight, wherein the lanthanum-based nanomaterial is selected from: La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 Any one or more combinations of NPs.

[0007] In the above application method, the lanthanum-based nanomaterial is dispersed in water to obtain a suspension; and then the suspension is sprayed on rice leaves.

[0008] In the above application method, the concentration of the suspension is 10-200 mg / L, preferably 100 mg / L.

[0009] In the above application method, La 10 Si 6 O 27 The NRs were rod-shaped with a length of 84.5 ± 34.3 nm and a width of 10.1 ± 2.7 nm.

[0010] In the above application method, La 10 Si 6 O 27 The NPs were spherical with a particle size of 82.6 ± 31.7 nm.

[0011] In the above application method, La(OH) 3 The NRs were rod-shaped with a length of 28.5 ± 8.9 nm and a width of 7.8 ± 2.1 nm.

[0012] In the above application method, La 2 O 3 The NPs were spherical with a particle size of 36.5 ± 8.4 nm.

[0013] In the above application method, the La 10 Si 6 O 27 NRs were prepared by the following method:

[0014] LaCl 3 . 6H 2 O、SiO 2 Dissolve in NaOH solution, mix well, transfer to a stainless steel reactor, and perform hydrothermal reaction in an oven at 180°C for 36 hours. After the reaction is completed, centrifuge, collect the precipitate, wash, and dry to obtain La 10 Si6 O 27 NRs.

[0015] In the above application method, La 10 Si 6 O 27 NPs were prepared by the following method:

[0016] Will La(NO 3 ) 3 and NH 3 Na 2 SiO 3 The solution was slowly added to ammonia water (pH 9) and stirred for reaction. After the reaction was completed, the mixture was centrifuged and the precipitate was collected. The precipitate was then calcined in a muffle furnace at 750°C for 6 hours to obtain La 10 Si 6 O 27 NPs.

[0017] In the above application method, La(OH) 3 NRs were prepared by the following method:

[0018] Will La(NO 3 ) 3 6H 2 O is dissolved in ethanol aqueous solution, stirred and mixed, and then slowly added to the NaOH solution and continued to stir and react. After the reaction is completed, centrifuge, collect the precipitate, wash, and dry to obtain La(OH) 3 NRs.

[0019] The present invention has the following beneficial technical effects:

[0020] The present invention disperses lanthanum-based nanomaterials in water to obtain a suspension; then sprays the suspension on rice leaves to control rice sheath blight by foliar spraying, and can control the disease index as low as 2.3±1.6, which has very good application prospects. The effects of different materials on controlling rice sheath blight are as follows: La 10 Si 6 O 27 NRs>La 10 Si 6 O 27 NPs>thiofuranamide>La(OH) 3 NRs>La 2 O 3 NPs≈Si ions>La ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (A)La 10 Si 6 O 27TEM images of NRs; (B) La 10 Si 6 O 27 TEM images of NPs; (C)La(OH) 3 TEM images of NRs; (D) La 2 O 3 TEM images of NPs; (E), (F), (G), and (H) are La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs and La 2 O 3 XRD patterns of NPs.

[0022] Figure 2 Apply different concentrations of La to the leaves 10 Si 6 O 27 Effects of NRs on aboveground and underground biomass (A) and disease index (B) of rice.

[0023] Figure 3 For foliar application of 100 mg / L La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 NPs, 123 mg / L chloride (LaCl 3 )、29mg / L silicate (Si(OH) 4 ) and 600 mg / L Thifluzamide on the aboveground and underground biomass (A) and disease index (B) of rice. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments.

[0025] The embodiments provided below are not intended to limit the scope of the present invention, and the steps described are not intended to limit the order of execution. Those skilled in the art can make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection required by the present invention.

[0026] Example 1 Preparation of lanthanum-based nanomaterials

[0027] Preparation of different lanthanum-based nanomaterials:

[0028] 2.47 g LaCl 3 . 6H 2 O and 0.5 g SiO 2 Dissolved in 24 mL 4.8 mol / L NaOH solution, stirred for 1 h, and then transferred to a 100 mL polytetrafluoroethylene-lined stainless steel reactor, followed by hydrothermal reaction in an oven at 180 °C for 36 h. The obtained solution was centrifuged (13000 rpm / min, 15 min) and the precipitate was collected. The precipitate was washed three times with ethanol and ultrapure water, respectively, and freeze-dried for 24 h to obtain La 10 Si 6 O 27 NRs.

[0029] 50 mL of 0.1 mol / L La(NO 3 ) 3 and 50 mL of 0.36 mol / L NH 3 0.06mol / L Na 2 SiO 3 The solution was slowly added to ammonia water (pH 9) and stirred at 400 rpm / min. After 30 min, the solution was centrifuged (13000 rpm / min, 15 min) and precipitated in a muffle furnace at 750 °C for 6 h to obtain La 10 Si 6 O 27 NPs.

[0030] Put 2.9g La(NO 3 ) 3 6H 2 O was dissolved in 100 mL of ultrapure water containing 20% ​​(v / v) ethanol, stirred at 50 °C for 8 h, and the solution was slowly added into 200 mL of 10 wt% NaOH solution and stirred for 3 h. The solution was centrifuged to obtain a precipitate, which was washed three times with ultrapure water and freeze-dried for 24 h to obtain La(OH) 3 NRs.

[0031] La 2 O 3 NPs (99.99%) were purchased from US Research Nanomaterials (Houston, TX, USA).

[0032] Material Characterization:

[0033] Transmission electron microscopy (TEM) was used to characterize the La 10 Si6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 The morphology and size of NPs were characterized. The results showed that La 10 Si 6 O 27 NRs are rod-shaped with a length of 84.5±34.3nm and a width of 10.1±2.7nm; La 10 Si 6 O 27 NPs are spherical with a particle size of 82.6±31.7nm; La(OH) 3 NRs are rod-shaped with a length of 28.5±8.9nm and a width of 7.8±2.1nm; La 2 O 3 NPs are spherical with a particle size of 36.5±8.4 nm ( Figure 1 AD).

[0034] La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 The XRD spectra of NPs showed that La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs and La 2 O 3 The characteristic peaks of NPs (such as Figure 1 EH).

[0035] Example 2 Application of lanthanum-based nanomaterials to control rice sheath blight

[0036] The La obtained in Example 1 10 Si 6 O 27 NRs were dispersed in water to prepare 10, 50, 100 and 200 mg / L La 10 Si 6 O 27 NRs suspension.

[0037] Rice (Oryza sativa L.) was used as the test crop, and the pathogen of rice sheath blight was Rhizoctonia solani. Rice seeds (Yliangyou 900) were sterilized in 5% sodium hypochlorite solution for 10 minutes and then rinsed with deionized water three times. After soaking in deionized water for 8 hours, the seeds were germinated on wet filter paper until the height of the rice plants reached about 5 cm. Seedlings with uniform growth were selected and transferred to pots containing 1 kg of soil. After growing for 4 weeks, 10 mL of different concentrations (10, 50, 100 and 200 mg / L) of La 10 Si 6 O 27 NRs suspension was sprayed on rice leaves. One week later, cylindrical mycelium (1 cm) cut from the edge of the PDA medium cultured with Rhizoctonia solani for 48 h was placed in the center of cotton and fixed on the rice stem. The rice not infected with the pathogen was the healthy control, and the rice infected with the pathogen and not sprayed with La 10 Si 6 O 27 The rice planted with NRs suspension was the infected control, and each treatment group was designed with 6 rice plants. For the healthy control and the infected control, an equal amount of deionized water was used to replace La 10 Si 6 O 27 NRs suspension. Two weeks after the pathogen infection, the disease index of rice was counted, and the rice was destructively sampled and the fresh weight of the aboveground part (stems and leaves) and underground part (roots) of rice was weighed.

[0038] According to the rice symptom evaluation index, the severity of the disease was assessed on a scale of 0-9, including 0 = no symptoms, 1 = lesions appearing at the base of rice seedlings, 3 = lesions extending to the third leaf from the bottom (the flag leaf is the 0th leaf from the bottom), 5 = lesions extending to the second leaf from the bottom, 7 = lesions extending to the first leaf from the bottom, and 9 = lesions spreading to the flag leaf or the whole plant withering.

[0039] The results showed that foliar application of 100, 200 mg / L La 10 Si 6 O 27 Compared with the infected control, the aboveground biomass of NRs increased by 45.2% and 38.3%, respectively. When 50, 100, and 200 mg / L La was applied to the leaves, 10 Si 6 O 27 NRs all showed the effect of inhibiting rice sheath blight, and the disease index was reduced by 46.2%, 62.4%, 46.2% and 10 mg / L La, respectively, compared with the infected control. 10Si 6 O 27 There was no significant difference in the anti-disease effect of NRs ( Figure 2 ). Therefore, the foliar application concentration of 100 mg / L is La 10 Si 6 O 27 The optimal application concentration of NRs for controlling rice sheath blight is shown in Table 1.

[0040] Table 1 Different concentrations of La 10 Si 6 O 27 Results of NRs in controlling rice sheath blight

[0041] <![CDATA[La 10 Si 6 O 27 NRs suspension concentration (mg / L)]]> Aboveground biomass (g) Underground biomass (g) Disease index Infected control 77.60 45.07 6.2±1.8 10 82.31 47.00 5.3±1.5 50 89.52 47.00 3.3±0.8 100 112.68 52.53 2.3±1.6 200 107.32 44.24 3.3±1.5

[0042] in, n is the symptom evaluation level of a single rice plant. The data are expressed as mean ± standard deviation (Mean ± SD). The research data were analyzed using the Origin 2021 program.

[0043] Example 3 Application of different lanthanum-based nanomaterials to control rice sheath blight

[0044] 100 mg / L La 10 Si 6 O 27 NRs, 100mg / L La 10 Si 6 O 27 NPs, 100mg / L La(OH) 3 NRs, 100mg / L La 2 O 3 NPs, 123mg / L LaCl 3 (La ions), 29mg / L Si(OH) 4 (Si ions) and 600 mg / L thiothiocarb were applied foliarly to another group of rice leaves, and the experimental process was consistent with Example 2.

[0045] The results showed that foliar spraying of La 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 NPs, Laions, Si ions and thiofuran significantly increased the aboveground biomass of rice compared with the infected control. 10 Si6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, Si ions and Thifluzamide significantly increased the underground biomass of rice, while La 2 O 3 NPs and La ions had no significant effect on rice underground biomass ( Figure 3 A). Foliar spraying 10 Si 6 O 27 NRs, La 10 Si 6 O 27 NPs, La(OH) 3 NRs, La 2 O 3 NPs significantly reduced the disease index of rice sheath blight, and the inhibitory capacity was La 10 Si 6 O 27 NRs>La 10 Si 6 O 27 NPs>La(OH) 3 NRs>La 2 O 3 NPs( Figure 3 B), indicating that La 10 Si 6 O 27 NRs had the best control effect on rice sheath blight and was significantly better than the traditional pesticide thiophanate-methyl. The specific results are shown in Table 2.

[0046] Table 2 Results of different pesticides controlling rice sheath blight

[0047] Treatment Group Aboveground biomass (g) Underground biomass (g) Disease index Infected control 73.47 48.98 7.0±1.4 <![CDATA[La 10 Yes 6 About 27 NRs]]> 111.19 52.77 2.2±1.1 <![CDATA[La 10 Si 6 O 27 NPs]]> 97.26 52.95 4.6±1.7 <![CDATA[La(OH) 3 NRs]]> 88.22 49.64 6.0±1.0 <![CDATA[La 2 O 3 NPs]]> 80.94 48.16 6.6±0.9 La ions 84.50 47.72 7.0±1.4 Si ions 76.58 50.64 6.6±0.9 Thifluzamide 86.16 53.07 5.4±0.9

[0048] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. Application of a lanthanum-based nanomaterial in controlling rice sheath blight, wherein the lanthanum-based nanomaterial is selected from: La 10 SiO 27 Nanorods, La 10 SiO 27 Any one or more combinations of nanoparticles; dispersing the lanthanum-based nanomaterial in water to obtain a suspension with a concentration of 100 mg / L; and then spraying the suspension on rice leaves; La 10 SiO 27 The nanorods were rod-shaped with a length of 84.5 ± 34.3 nm and a width of 10.1 ± 2.7 nm; La 10 SiO 27 The nanoparticles are spherical and have a particle size of 82.6±31.7nm.

2. The use according to claim 1, characterized in that: The La 10 SiO 27 The nanorods were prepared by the following method: LaCl3 . 6H2O and SiO2 were dissolved in NaOH solution, mixed, transferred to a stainless steel reactor, and subjected to hydrothermal reaction in an oven at 180°C for 36 hours. After the reaction was completed, the reaction was centrifuged, the precipitate was collected, washed, and dried to obtain La 10 SiO 27 Nanorods.

3. The use according to claim 1, characterized in that: La 10 SiO 27 The nanoparticles were prepared by the following method: La(NO3)3 and Na2SiO3 solution containing NH3 were slowly added into ammonia water with a pH value of 9 at the same time, stirred for reaction, centrifuged and the precipitate was collected, and then calcined in a muffle furnace at 750℃ for 6h to obtain La 10 SiO 27 Nanoparticles.

Images