Mesoporous nanosilica loaded with Fe 2+ for use in modulating stem dwarfing in rice

Abstract

The application belongs to the technical field of plant growth regulators, and particularly relates to application of mesoporous nano-silica loaded with Fe 2+ in regulating stem dwarfing of rice. When the mesoporous nano-silica loaded with Fe 2+ is applied in regulating stem dwarfing of rice, not only can the stem internode length of a high-stem variety be significantly shortened to reduce plant height, but also the stem thickness can be increased, and the effects of enhancing lodging resistance and optimizing stem material transportation are achieved; in addition, the Fe and Zn contents in brown rice can be significantly increased within a safe edible range, and the effect of trace element nutrition strengthening is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plant growth regulators, and more particularly relates to application of mesoporous nanosilica loaded with Fe 2+ in regulating stem dwarfing of rice. BACKGROUND

[0002] In the process of high-yield and high-efficiency cultivation of rice, the plant height of the field population needs to be controlled within a suitable range, so that the high-yield population has a larger photosynthesis area and more organic matter accumulation, and at the same time, the plant height cannot be too high, and the gravity center of the plant cannot be moved upward to easily cause lodging, thereby greatly reducing yield and quality.

[0003] Colored rice is a special ecological type of rice resource, and its nutritional quality is closely related to human health. In particular, red rice contains natural red color on the surface and is rich in antioxidant functional phenolic substances. Moreover, red rice resources are abundant in China, and have a long history of cultivation. However, they are mostly local rice resources, are cultivated in scattered regions, and have problems such as low yield and narrow ecological adaptability, and are only cultivated in small-scale and scattered areas and have not been applied in large areas in production.

[0004] At present, the main technical measures for optimizing the characteristics of crop stems are: (1) strengthening the regulation and control measures of water, fertilizer, density and the like in cultivation management and the application of silicon fertilizer; (2) selecting and improving the plant type structure of rice varieties by genetic breeding means. However, these measures have problems such as low absorption and utilization rate of traditional fertilizers, long time consumption of genetic breeding, difficulty or poor effect of improvement, and the like.

[0005] For example, the prior art discloses a plant growth regulating composition for greenhouse rice, which mainly consists of calcium thidiazuron and brassinolide. The calcium thidiazuron and brassinolide are used in combination to dwarf the stems of rice, increase the chlorophyll content in leaves, and increase the yield of rice. However, the composition needs to be prepared into a wettable powder with other auxiliary materials for application, and has the problem of low absorption and utilization rate, which leads to poor dwarfing effect of rice stems. SUMMARY

[0006] The purpose of the present application is to overcome the defects or deficiencies of existing plant production regulators for dwarfing rice stems, and to provide application of mesoporous nanosilica loaded with Fe 2+ in regulating stem dwarfing of rice.

[0007] The above purpose of the present application is achieved by the following technical solutions.

[0008] The present application protects the application of mesoporous nanosilica loaded with Fe 2+ in regulating stem dwarfing of rice.

[0009] Nanomaterials are increasingly used in plant production. Due to the advantages of nanoscale, nanoscale essential elements are more easily absorbed by plants to promote growth and metabolism. Among them, mesoporous silica nanoparticles (MSNs) have an ordered mesoporous channel structure, which can regulate the release rate of effective ingredients, and have been widely used to improve the absorption and transport performance of pesticides. Based on this, the present application aims to use nanotechnology to overcome the defects or deficiencies of existing rice stem dwarf plant production regulators.

[0010] The Fe 2+ -loaded mesoporous nanosilica of the present application uses mesoporous silica as a carrier and a sustained-release agent, which can effectively avoid the oxidation of Fe 2+ During foliar spraying, due to the obstruction of the leaf surface or the surface Fe 2+ oxidation, and the Fenton reaction induced by Fe 2+ in the plant body, the foliar application of Fe 2+ to rice plants can cause oxidative stress in a short period of time, thereby facilitating the efficient entry of Fe 2+ into rice plants to promote their growth and metabolism. The ordered mesoporous channel structure of mesoporous nanosilica can regulate the release rate of Fe 2+ to facilitate better absorption of Fe 2+ ; moreover, the silicon element in mesoporous nanosilica also has a promoting effect on rice growth. The inventors found that the combination of mesoporous nanosilica and Fe 2+ can significantly reduce the height of high-stem varieties of rice while increasing their stem thickness; it can also significantly increase the Fe and Zn content in brown rice, enhancing the trace element nutrition of the grains without exceeding the safe edible content.

[0011] Specifically, the Fe 2+ -loaded mesoporous nanosilica includes mesoporous nanosilica and Fe 2+ , and the Fe 2 + is dispersed in the pores of the mesoporous nanosilica and on its surface.

[0012] In a specific embodiment, the average particle size of the Fe 2+ -loaded mesoporous nanosilica is 80-112 nm. When the average particle size of the Fe 2+ -loaded mesoporous nanosilica is 80-112 nm, it not only has a more suitable Fe 2+ loading capacity, but also can efficiently enter the interior of the plant through the plant leaf surface to regulate rice growth.

[0013] Specifically, the loading rate of Fe 2+ is 10%-45%.

[0014] In a specific implementation, the above-mentioned load Fe 2+ Mesoporous nano-silica was prepared by the following method:

[0015] Mesoporous nano-silica was added to an aqueous solution of ferrous salt and stirred overnight to obtain Fe-loaded material. 2+ Mesoporous nano-silica. Specifically, the ferrous salt can be one or more of FeSO4, FeCl2, and Fe(NO3)2.

[0016] Mesoporous nano-silica can be commercially available or made at home using the following methods:

[0017] 1 g of dodecyl ammonium bromide (CTAB) was dissolved in 480 mL of water, and 0.28 g of NaOH was added. After stirring and dissolving, the mixture was heated to 80 °C, and 5.3 mL of TEOS was added while stirring vigorously. The reaction was carried out at 80 °C for 2 h. Then, 0.5 mL of 3-Aminopropyltriethoxysilane (APTES) was added, and stirring was continued for 2 h. Finally, the mixture was filtered, washed with water and methanol, dried under vacuum, dispersed in ethanol, and HCl was added to remove CTAB. The mixture was then washed with ethanol and water, and dried under vacuum to obtain mesoporous nano-silica.

[0018] Specifically, the aforementioned load Fe 2+ The method for preparing mesoporous nano-silica includes the following steps:

[0019] Mesoporous nano-silica (MSN) was mixed with a 0.1%–5% (w / w) FeSO4 aqueous solution and stirred overnight. After centrifugation and precipitation, the Fe-loaded product was obtained. 2+ The mesoporous nano-silica; the solid-liquid ratio of the mesoporous nano-silica to the FeSO4 aqueous solution is (0.3-0.7):(5-15) g / mL. More preferably, the solid-liquid ratio of the mesoporous nano-silica to the FeSO4 aqueous solution is 0.5:10 g / mL.

[0020] Load Fe 2+ Fe from mesoporous nano silica 2+ Load factor is determined in the following way:

[0021] Take the supernatant after centrifugation and detect the Fe content in the supernatant (Nanjing Jiancheng Bioengineering Research Institute, Tissue Iron Assay Kit). Then calculate the Fe content using the following formula. 2+ Load rate;

[0022] Fe 2+Loading rate = (total content of divalent iron salt - content of divalent iron salt in supernatant) / total content of divalent iron salt * 100%.

[0023] In the specific embodiment, the rice plant height is medium-high stem (100 cm≤plant height≤120 cm) and / or high stem (plant height>120 cm); the rice is colored rice (red rice) and / or white rice.

[0024] Specifically, the applied method is: mixing the mesoporous nanosilica loaded with Fe 2+ with water to make a dispersion, and then performing foliar spraying treatment.

[0025] Optionally, the concentration of the mesoporous nanosilica loaded with Fe 2+ in the above dispersion is 0.036-17.98 mM; preferably, the concentration is 0.2-0.4 mM; more preferably, the concentration is 0.27 mM.

[0026] The foliar spraying treatment is performed at the booting stage and the heading stage of the rice plant, respectively. The spraying time can be selected as around 6 pm, and the aboveground part of each plant is sprayed, and the spraying standard is that the leaf surface is wet and drops water.

[0027] The present application has the following beneficial effects:

[0028] The application of the mesoporous nanosilica loaded with Fe 2+ to the regulation of rice stem dwarfing can not only significantly reduce the plant height of high stem varieties, but also increase the stem diameter, has the effect of optimizing stem material transport or anti-lodging; and can significantly increase the Fe and Zn content in brown rice, has the effect of quality strengthening of grain trace element nutrition, pigment function, etc. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 TEM of MSN and FeSO4-MSN and solution and particle size distribution diagram.

[0030] Figure 2 Filling effect of MSN loaded with different concentrations of FeSO4 solution and FeSO4-MSN release FeSO4 effect diagram.

[0031] Figure 3 Rice leaf SPAD value after 7 days of treatment with different concentrations of FeSO4-MSNs, red rice plant phenotype diagram, red rice leaf flavonoid content, and red rice leaf iron content diagram.

[0032] Figure 4 Foliar spraying FeSO4-MSN to regulate rice stem internode phenotype diagram.

[0033] Figure 5Figure 1. Effects of foliar spraying of FeSO4-MSN on the shortening of the third internode of different rice stems.

[0034] Figure 6 Analysis of rice stem metabolites and staining intensity of metabolites after foliar spraying with FeSO4-MSN.

[0035] Figure 7 Figure 1 shows the effect of FeSO4-MSN on the content of trace elements (Fe, Zn) in brown rice after foliar spraying. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0037] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0038] Example 1

[0039] Preparation of mesoporous nano-silica (MSN):

[0040] Under low stirring (200 rpm), hexadecyltrimethylammonium chloride (CTAB, 0.45 g) was dissolved in 180 mL of 16.7% ethanol aqueous solution at 70 °C. Then, 4 mL of ammonia water (25%) was added. After the solution became clear, 1.5 mL of tetraethyl silicate (TEOS) was added dropwise. The stirring speed was adjusted to 300 rpm and the reaction was carried out for 24 h. The product was collected by centrifugation and washed three times with deionized water and ethanol to remove residual reactants. Then, it was treated in a muffle furnace at 550 °C for 6 h to obtain mesoporous nano silica (MSN).

[0041] Example 2

[0042] Load Fe 2+ Preparation of mesoporous nano-silica (FeSO4-MSNs):

[0043] Weigh 0.5g of MSN powder from Example 1, add it to 10mL of a 5% (w / w) FeSO4 aqueous solution, and stir overnight to obtain the Fe-loaded product. 2+ Mesoporous nano-silica.

[0044] The loading rate of Fe in the precipitated FeSO4-MSNs can be calculated according to the Fe content in the supernatant after centrifugation (Nanjing Jiancheng Biological Engineering Research Institute, tissue iron determination kit), and the dispersion of 0.036 mM Fe-MSNs, 0.09 mM Fe-MSNs, 0.18 mM Fe-MSNs, 0.27 mM Fe-MSNs, 0.36 mM Fe-MSNs, 1.80 mM Fe-MSNs, 3.60 mM Fe-MSNs, and 17.98 mM Fe-MSNs can be prepared according to the loading rate.

[0045] Example 3

[0046] Rice seeding, spraying treatment, concentration screening:

[0047] The red rice self-bred variety "Luotian Hongmi" is used, which is referred to as RM1, for potting and spraying treatment and concentration screening.

[0048] The above rice seeds are soaked and germinated for 5 days, then seeded and potted for 30 days. Two-leaf-one-heart seedlings with consistent growth are selected for concentration screening of slow-release Fe-MSNs (0.036 mM, 0.09 mM, 0.18 mM, 0.27 mM, 0.36 mM, 1.80 mM, 3.60 mM, and 17.98 mM), and 0.36 mM FeSO4 solution and H2O are used as controls. The spraying time is selected at 6 pm, and the aboveground part of each plant is sprayed, with the spraying standard being leaf wetness with water droplets. Regular water, fertilizer, and pest control management are performed. The growth status and growth of the rice are observed during the period.

[0049] Example 4

[0050] Measurement of leaf SPAD value, plant height, and stem characteristics:

[0051] After two spraying treatments for 7 days, the relative amount of chlorophyll in the flag leaf (SPAD value) is measured using a SPAD-502 type chlorophyll meter. Three plants are measured, with 3 leaves per plant, and 10 measurements are taken per leaf.

[0052] At DAF 15, which is the mid-grain filling stage, the plant height, internode length, and thickness are measured, and the internode length-thickness ratio change is calculated based on the stem characteristics (Kong et al 2013).

[0053] Example 5

[0054] Rice seeding and spraying treatment:

[0055] Nine red rice varieties (No. GH1-4, XH5-8, RM1, wherein RM1 is a self-bred variety "Luotianhongmi") with different color gradients and one common white rice 9311 were respectively seeded and sprayed, and the above varieties had a basic consistent growth period of about 130 days.

[0056] Table 1: Rice material number and characteristics

[0057] No. Name Plant height GH1 Zehong No. 1 Medium-high stem GH2 Hong 231 Medium-high stem GH3 GH3 Medium-high stem GH4 Runzehongmi High stem XH5 Local Hongmaogu High stem XH6 Luotan Girl Hong High stem XH7 DY Hongmi Medium-high stem XH8 XH8 High stem RM1 Luotan Hongmi Medium stem 9311 Ordinary white rice Medium stem

[0058] The above rice seeds were soaked and germinated for 5 days before being seeded and potted for 30 days. Then two-leaf-one-heart and consistent growth seedlings were selected for field transplanting and partial potting. The potted material RM1 was used for concentration screening (0.036 mM, 0.09 mM, 0.18 mM, 0.27 mM, 0.36 mM, 1.80 mM, 3.60 mM, 17.98 mM) of slow-release Fe-MSNs treatment, and regular water, fertilizer and pest control management. The growth conditions and growth of rice were observed during the period.

[0059] When the plants grow to the booting stage and the heading stage, leaf spraying treatment is carried out. Select consistent growth materials for two spraying treatments. The first spraying is carried out when more than 70% of the rice is in the booting stage, and the second spraying is carried out in the heading stage. 0.27 mM Fe-MSNs is the best concentration in the above screening, and 0.36 mM FeSO4 solution and H2O are used as controls. The spraying time is selected at 6 pm, and the aboveground part of each plant is sprayed, and the spraying standard is that the leaf surface is wet and dripping water. The plant height and the third node length of the rice are shown in Table 2.

[0060] Table 2

[0061]

[0062] As can be seen from Table 2, after spraying Fe-MSNs, the plant height of most rice plants becomes shorter except for XH7 and 9311, among which GH2, XH5, XH6 and XH8 have significantly reduced plant height. In particular, after spraying Fe-MSNs, the third node length of the stem of most varieties is shortened, which has the effect of optimizing the stem lodging resistance.

[0063] Example 6

[0064] Stem lignin and cellulose staining:

[0065] Rice stem staining was performed using 0.001% (w / v) of Auramine O (CAS No. 2465-27-2) and 0.1% (w / v) Calcofluor white according to the method reported by Kim et al. (2021). The rice stem was sectioned with a blade and then placed on a glass slide with drops of Auramine O solution for 10 min, then placed in Calcofluor white solution for 10 min, taken out and placed on a glass slide with drops of clean water, covered with a cover glass, and placed under a fluorescence microscope (Nikon ECLIPSE Ti) under the FITC channel to observe the lignin staining, and under the DAPI channel to observe the cellulose staining without moving the slide.

[0066] Example 7

[0067] Trace element detection:

[0068] The content of each element was determined by nitric acid digestion and ICP-AES / Ms. Mature grains were divided into husks, brown rice, polished rice, and pericarp. The detection service was provided by Nanjing Kavens Detection Technology Co., Ltd.

[0069] After digestion of the sample, the content of Fe, Zn, Cu, Mn, and Cd elements in the digestion filtrate was determined by American Hot ICP inductively coupled plasma spectrometer (ICAP6300 model) (GB 5009.268-2016). The digestion reagent was 70% concentrated nitric acid (16M, specific gravity 1.42) and 70% perchloric acid (11.6M, specific gravity 1.66), and the mixed acid was prepared according to the solution volume ratio of concentrated nitric acid: perchloric acid = 10:1.

[0070] The digestion process is as follows:

[0071] The sample was dried in a drying oven (model: DHG-9240A), crushed and sieved. 0.5g of powder was accurately weighed on an electronic balance (model: BSM220.4, Shanghai Zhuojing, Shanghai) in a glass digestion vessel. The sample containing ethanol or carbon dioxide was first heated at low temperature on a constant temperature electric hot plate to remove ethanol or carbon dioxide. 10mL of concentrated nitric acid-perchloric acid digestion solution was added, and the digestion was carried out on an electric hot plate digestion device until the digestion solution was colorless and transparent or slightly yellow. Then cool to room temperature, add ddH2O to 50mL and mix thoroughly, filter and determine the content of trace elements in the filtrate.

[0072] It can be seen from Figure 1 that the mesoporous nanosilica (MSN) synthesized in Example 1 is spherical particles (as shown in Figure 1 A), with a particle size of 50.86±8.3nm (as shown in Figure 1 D); the mesoporous nanosilica loaded with Fe 2+ in Example 2 is irregularly particulate (as shown inFigure 1 As shown in B), a distinct coating layer can be observed, and its particle size is 96.25±15.71 nm (as shown in B). Figure 1 As shown in D), this fully demonstrates the successful loading of FeSO4. Figure 1 C represents the load Fe. 2+ The white suspension formed by the mesoporous nano-silica and water indicates that the Fe is loaded... 2+ Mesoporous nano-silica can be uniformly dispersed in water to form a dispersion, providing a basis for foliar spraying.

[0073] Depend on Figure 2 A indicates that when the mass percentage of FeSO4 in the FeSO4 aqueous solution is 0.1%–5%, the loaded Fe... 2+ Fe in mesoporous nano silica 2+ The loading rate of FeSO4 gradually increases, but the loading of mesoporous silica is limited and does not increase indefinitely with the mass percentage of FeSO4. Furthermore, Fe... 2+ An increase in load factor will also affect the load Fe 2+ The particle size of mesoporous nano-silica affects its penetration into rice plants. Therefore, a FeSO4 aqueous solution with a FeSO4 mass percentage of 0.1%–5% yields better results. Figure 2 From B, we can know that the load Fe 2+ Mesoporous nano-silica can continuously and slowly release Fe 2+ Over a week, its ability to regulate Fe was fully demonstrated. 2+ The release rate of Fe is slow and continuous. 2+ This is so that the rice can fully absorb the nutrients.

[0074] Depend on Figure 3 It was found that when foliar spraying concentrations of FeSO4-MSN were screened at eight levels (0.036 mM, 0.09 mM, 0.18 mM, 0.27 mM, 0.36 mM, 1.80 mM, 3.60 mM, and 17.98 mM), the highest SPAD value (44.46) was observed after spraying with 0.27 mM FeSO4-MSN. Figure 3 A) The leaf extract has a high flavonoid content of 1.03 mg / g. Figure 3 C), the highest iron content in the leaves was 0.73 μg / g ( Figure 3 D). Compared with FeSO4 spraying, leaves sprayed with FeSO4-MSN did not develop red, rust-like spots. Figure 3 B). In summary, the optimal concentration for spraying FeSO4-MSN is 0.27 mM.

[0075] Depend on Figure 4It was found that foliar spraying with 0.27 mM FeSO4-MSN on 10 rice varieties significantly shortened the third internode of the rice stem. Figure 5 It was found that foliar spraying with 0.27mM FeSO4-MSN regulated the ratio of the length and thickness of the third internode in rice stems, especially for special colored rice varieties GH1, GH2, GH3, XH5, XH8, and RM1, showing significant regulation of stem characteristics and a marked effect of shortening internode length and increasing internode thickness.

[0076] Depend on Figure 6 It can be seen that spraying 0.27 mM FeSO4-MSN regulated and enhanced the accumulation of lignin and cellulose metabolites in rice stems. Figure 7 It can be seen that spraying 0.27mM FeSO4-MSN significantly increased the concentration of trace elements Fe and Zn in mature rice, demonstrating a nutritional fortification effect within a safe range.

[0077] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. Use of mesoporous nanosilica loaded with Fe 2+ for modulating stem dwarfing in rice. The mesoporous nanosilica loaded with Fe 2+ is mixed with water to make a dispersion liquid, and then foliar spraying treatment is performed. wherein The rice is selected from one or more of Zehong No. 1, Hong 231, GH3, Runzehongmi, Benlizhongmaogu, Luotannv'erhong, XH8, or Luotanhongmi; The Fe 2+ loading rate is 10% to 45%.

2. Use according to claim 1, characterized in that, The load Fe 2+ Mesoporous nano-silica includes mesoporous nano-silica and Fe 2+ The Fe 2+ The pores and surface of mesoporous nano-silica are dispersed.

3. Use according to claim 2, characterized in that, The mesoporous nanosilica loaded with Fe 2+ The average particle size of the mesoporous nanosilica loaded with Fe is 80-112 nm.

4. The use according to any one of claims 2 to 3, characterized in that, Mesoporous nanosilica loaded with Fe 2+ was prepared by the following preparation method: The mesoporous nanosilica is mixed into the aqueous solution of divalent iron salt to obtain mesoporous nanosilica loaded with Fe 2+ .

5. The use according to claim 1, characterized in that, The dispersion is loaded with Fe 2+ The concentration of mesoporous nano-silica ranged from 0.036 to 17.98 mM.

6. The use according to claim 1, characterized in that, The foliar spraying treatment is spraying treatment at the booting stage and the heading stage of the rice plant, respectively.

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