A semi-solid gel for plant root growth observation and its preparation method and application

Abstract

The application discloses a semi-solid gel for plant root growth observation and a preparation method and application thereof. The semi-solid gel is prepared by the following steps: 100 parts of plant nutrient solution is heated to 65-80 DEG C, 0.2-0.5 parts of carbomer U20 is added, and stirring is carried out under the condition of 200-400 revolutions per minute per minute until the carbomer U20 is fully dissolved; then 0.05-0.3 parts of high molecular water-absorbing resin is added, and stirring is carried out under the condition of 20-50 revolutions per minute per minute until the high molecular water-absorbing resin is fully dissolved; if bubbles appear, the bubbles are eliminated by ultrasonic waves. The semi-solid gel can meet the needs of simulating natural growth of roots, can meet the needs of three-dimensional space growth and observation of roots, is suitable for open environment culture, can guarantee that clean and less-damaged living root samples are collected in the future, and has the advantages of simple process, simple raw materials and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of plant cultivation, and in particular relates to a semi-solid gel for observing plant root growth, a preparation method and an application thereof. Background Art

[0002] Plant roots are crucial for obtaining water and nutrients. Observing root growth and development not only helps identify effective methods for regulating root growth and improving plant productivity, but also allows for timely identification of changes in root responses to the environment, enabling rapid action to improve plant resilience to adverse environmental conditions. Non-destructive in situ observation is crucial for accurately analyzing root growth characteristics. Unfortunately, most current root studies under soil cultivation conditions rely on destructive sampling and analysis. While isotope tracing, micro-root tube analysis, nuclear magnetic resonance imaging, and neutron radiography can achieve non-destructive observation, these methods are extremely expensive and only provide incomplete root morphological data. The transparent root chamber method is considered a superior method for non-destructive in situ observation of root growth in soil. However, this method only observes roots that touch the transparent surface, resulting in high errors in fine root analysis and inability to capture the entire root system.

[0003] Using a transparent substrate as a non-soil medium for plant growth to observe plant root growth remains the primary method. The main methods include hydroponics, aeroponics, gel culture, and paper-based culture. Hydroponics is the most widely used method, primarily involving growing plants on a solid support and in a nutrient solution containing essential nutrients for plant growth. Aeroponics uses an air compressor to atomize the nutrient solution and spray it onto the roots. Gel culture uses a gel, such as agar, mixed with nutrient solution as the cultivation medium. Paper-based culture allows roots to grow attached to germination paper, where the nutrient solution permeates the paper through capillary action and is then absorbed by the roots. Aeroponics, gel culture, and paper-based culture are extensions of hydroponics, differing primarily in how the nutrient solution is supplied to the roots. Although these methods allow roots to grow in a visually penetrating environment and can meet the needs of non-destructive in situ observation, they all have certain defects: (1) The paper-based culture method belongs to the category of two-dimensional observation and cannot meet the needs of observing the spatial growth of the root system; (2) Although the aeroponic method and hydroponic method can allow the root system to grow in three dimensions, they lack a supporting matrix, and the root system configuration is very different from that in the soil. For example, the hierarchical growth of the root system, the root branching angle and the topological structure are significantly smaller than those in soil cultivation; (3) The gel culture method can reduce the spatial configuration difference with soil cultivation, but this method is not conducive to subsequent root sampling and has stricter requirements on the environment and operation.

[0004] In summary, the existing root observation methods have the following main problems: (1) Due to the limitation of soil invisibility, the observation of the root system is hindered when the root system grows in the soil, and it is difficult to observe the growth morphology and status of the root system in real time; (2) When collecting the root system, it is not easy to obtain a complete plant root system, and the root system is easily damaged; (3) Observation methods such as the transparent root chamber method cannot accurately reflect the growth of the root system in a natural state, and can only observe the growth of part of the root system, and the types of plants planted in the root chamber are limited; (4) The support force of the culture medium such as the hydroponic method is relatively small, and the root growth is affected by gravity, so the growth morphology of the root system in a natural state cannot be observed; (5) Methods such as isotope tracing method, micro-root tube method, nuclear magnetic resonance imaging method and neutron radiography method are complex to operate, high in cost, and have strict requirements on plant cultivation conditions; (6) The agar medium currently commonly used as a culture medium requires that plants be cultivated in a sterile environment, and has strict requirements on the environment and operation.

[0005] Finding a cultivation method that can not only meet the needs of three-dimensional root growth and observation, but also ensure the subsequent collection of clean and less damaged living root samples, and is suitable for open environments, is a difficulty in observing plant root growth and is also a problem that has not yet been solved in the industry. Summary of the Invention

[0006] The purpose of the present invention is to provide a semi-solid gel for observing plant root growth and a preparation method thereof. The semi-solid gel can be used for observing plant root growth under open culture, so as to realize in situ accurate observation of root spatial growth and non-destructive collection of living root samples in an open environment, providing support for the research of plant roots.

[0007] In order to achieve the purpose of the invention, the designed gel formula must meet the following conditions: ① low strength and weak adhesion but good supporting capacity, which can better simulate the growth of roots in the soil, but avoid the culture medium being too hard and excessive adhesion of fine roots; ② stable properties, not easily affected by pH changes, and not easily denatured with metal ions, avoiding affecting the activity of nutrients; ③ high transparency, which is convenient for root observation; ④ harmless to plants, avoiding inhibition of root growth; ⑤ can be antiseptic and antibacterial, avoiding mildew during root growth.

[0008] The first object of the present invention is to provide a method for preparing a semi-solid gel for observing plant root growth, comprising the following steps:

[0009] 100 parts by mass of plant nutrient solution is prepared, heated to 65-80° C., 0.2-0.5 parts by mass of Carbomer U20 is added, and the solution is stirred at 200-400 revolutions per minute under heat preservation conditions until the solution is fully dissolved. Then, 0.05-0.3 parts by mass of a high-molecular-weight water-absorbing resin is added, and the solution is stirred at 20-50 revolutions per minute under heat preservation conditions until the solution is fully dissolved. If bubbles appear, they are eliminated by ultrasound. Thus, a semi-solid gel is prepared.

[0010] Preferably, the plant nutrient solution is Hoagland's nutrient solution, MS nutrient solution, Yamazaki nutrient solution, horticultural balanced nutrient solution or other commonly used nutrient solutions.

[0011] Preferably, the preparation method comprises the following steps:

[0012] 100 parts by mass of plant nutrient solution was prepared, heated to 80° C., 0.5 parts by mass of carbomer U20 was added, and the solution was stirred at 300 rpm under heat preservation until fully dissolved. Then, 0.2 parts by mass of a high molecular weight water-absorbing resin was added, and the solution was stirred at 30 rpm under heat preservation until fully dissolved. If bubbles appeared, they were eliminated by ultrasound. Thus, a semi-solid gel was prepared.

[0013] The second object of the present invention is to provide a semi-solid gel prepared according to the method for preparing the semi-solid gel for observing plant root growth.

[0014] The third object of the present invention is to provide the use of the semi-solid gel in in-situ non-destructive observation of plant root growth.

[0015] Preferably, the application comprises the step of utilizing the semi-solid gel as a plant culture matrix.

[0016] Preferably, the application comprises the following steps:

[0017] The semi-solid gel is placed in a transparent root box (if bubbles appear, it needs to be placed in an ultrasonic cleaner for ultrasonic elimination of bubbles), and then the plant is transplanted into the root box. The root system is appropriately loosened so that the root system is naturally distributed in the semi-solid gel. The stems of the above-ground part of the plant are fixed, and the root box is wrapped with light-proof material. The plant is cultured and the growth of the plant root system is observed in due course.

[0018] Preferably, the plant is a herbaceous plant, a shrub plant or a tree plant seedling.

[0019] Preferably, the herb is Caladium nigra, the shrub is Schefflera chinensis, and the tree is Glechoma longituba.

[0020] For in situ non-destructive observation and sampling analysis of plant root growth, if dynamic in situ analysis of root morphological and configuration changes is required, two-dimensional or three-dimensional root growth photos can be obtained first, and then analyzed with the help of relevant root analysis software; after the cultivation is completed, if non-destructive collection of living root samples is required, the roots and semi-solid gel can be poured into water, and the complete living root samples can be separated by appropriate rinsing.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) It meets the needs of simulating the natural growth of the root system and can meet the three-dimensional spatial growth and observation of the root system. Unlike existing hydroponics, the semi-solid gel of the present invention has a certain support force, ensuring that the root system stretches naturally, and the lateral roots and fine roots are spread out at a certain angle, which better simulates the growth of the root system in the soil.

[0023] (2) It ensures that clean and less damaged live root samples are collected later. Unlike the existing agar gel, the semi-solid gel of the present invention has a soft texture and weak root adhesion, and is easy to separate from the root system, avoiding the difficulty in separating the root system and the gel and breaking the fine roots during subsequent sampling, and a complete root system can be obtained.

[0024] (3) It is suitable for cultivation in an open environment. Unlike the existing agar gel, the gel formula selected by the present invention has strong antiseptic and antibacterial capabilities, does not require strict aseptic treatment and closed conditions for cultivation, and can avoid mildew during root growth in an open environment.

[0025] (4) The process is simple and easy to operate. The key process of the present invention is to prepare a semi-solid gel, which only requires a simple water bath, stirring and ultrasonic defoaming, and the required instruments and equipment are simple.

[0026] (5) The raw materials are simple and low in cost. The polymer water-absorbing resin and carbomer U20 selected in the present invention are gel materials widely used in agriculture, medical industry, etc. They are easy to obtain, low in price, and used in small amounts. The overall cost of use is much lower than that of existing agar gel.

[0027] (6) Solve the shortcomings of raw materials and achieve complementary advantages between raw materials. Polymer water-absorbing resin is a type of polymer with a three-dimensional network structure. Because its molecular chain contains strong hydrophilic groups such as carboxyl, sulfonic acid, amide, and hydroxyl groups, it is mostly used as a water-retaining agent to improve soil moisture conditions and physical properties. Carbomer U20 is a cross-linked copolymer formed by the polymerization of C10-30 alkyl acrylate polymers. It has the characteristics of biocompatibility, bioadhesion and biodegradability, and is an excellent water-soluble matrix. These two gels are easily hydrated after being placed for a period of time, resulting in hydration and stratification of the gel. Polymer water-absorbing resins with higher concentrations have extremely strong water absorption and absorb a large amount of water, resulting in an increase in salt in the culture medium and a decrease in water available to plants, which in turn causes an imbalance in root osmosis. In addition, the hydrolysis of the polymer water-absorbing resin alone produces components such as acrylic acid, acrylamide or sodium ions that are not conducive to the growth of plant roots, thereby inhibiting plant growth. The polymer water-absorbing resin and carbomer U20 at an appropriate concentration are compounded to react under the conditions of the present invention to form a more stable and safe colloid, which weakens the water competition between the polymer water-absorbing resin and the root system, prevents the hydrolysis of the polymer water-absorbing resin, reduces the generation of toxic substances such as acrylic acid, acrylamide or sodium ions, and also prevents the carbomer U20 from being hydrated and denatured to generate precipitation when left for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the stability of various gel compound nutrient solutions.

[0029] Figure 2 It is safe to add preservatives to food gels.

[0030] Figure 3 It is the compounded form of industrial gel.

[0031] Figure 4 It is an industrial gel compound safety.

[0032] Figure 5 The changes in root growth of Schefflera chinensis and Colocasia nigra in different treatments after five weeks of planting.

[0033] Figure 6 Figure 2 shows the changes in fresh weight of Schefflera chinensis and Colocasia esculenta under different treatments. Note: Figures a and b show the fresh weight of Schefflera chinensis; Figures c and d show the fresh weight of Colocasia esculenta. The data are the mean ± standard error of 4 replicates. Different letters indicate significant differences among different treatments at the same time (P < 0.05, Duncan).

[0034] Figure 7 Figure 2 shows the changes in nutrients of Schefflera chinensis under different treatments. Note: Figures a, b, and c show the aboveground parts of Schefflera chinensis; Figures d, e, and f show the root system of Schefflera chinensis. The data are the mean ± standard error of 4 replicates. Different letters indicate significant differences among different treatments at the same time (P < 0.05, Duncan).

[0035] Figure 8 The nutrient changes of black leaf taro in different treatments; Note: Figures a, b and c, aboveground parts of black leaf taro; Figures d, e and f, roots of black leaf taro; data are the mean ± standard error of 4 replicates, different letters indicate significant differences among different treatments at the same time (P < 0.05, Duncan).

[0036] Figure 9 Figure 2 shows the changes in inflorescence biomass among different treatments. Note: Figure a: plant height; Figure b: ground diameter; Figure c: aboveground biomass; Figure d: root fresh weight. Data are mean ± standard error (n = 3). Identical letters above the columns indicate no significant differences among treatments (P > 0.05, Duncan's method).

[0037] Figure 10 Figure 3. Changes in root morphology of Echinops chinensis under different treatments. Note: Figure a: total root length; Figure b: root surface area; Figure c: root volume; Figure d: root diameter. Data are mean ± standard error (n = 3). Identical letters above the columns indicate no significant differences among treatments (P > 0.05, Duncan's method).

[0038] Figure 11Figure 2 is the change of nutrient content in the inflorescence under different treatments; Note: Figure a: nitrogen content in the aboveground part; Figure b: phosphorus content in the aboveground part; Figure c: potassium content in the aboveground part; Figure d: nitrogen content in the root system; Figure e: phosphorus content in the root system; Figure f: potassium content in the root system; Data are mean ± standard error (n = 3), and the same letters in the columns indicate no significant difference among different treatments (P>0.05, Duncan's method). DETAILED DESCRIPTION

[0039] The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention.

[0040] The 1 / 4 Hoagland's nutrient solution used in the following examples was prepared by diluting the concentrations of all components of the commonly used (commercially available) Hoagland's nutrient solution in the art to 1 / 4 of the original concentration of the Hoagland's nutrient solution.

[0041] The following examples used gellan gum (low acyl type, food grade, purity> 95%), locust bean gum (food grade, purity> 95%), agar powder (gel strength 800-1200g / cm 2 , purity>95%), xanthan gum (food grade, 1% viscosity 1300-1700 m / pas, purity>91%), carrageenan (K type, food grade, purity>95%) and artemisia seed gum (food grade, purity>95%) were purchased from Nantong Aokai Biotechnology Development Co., Ltd. Hydroxyethyl cellulose (HHR-250, 1% viscosity 3400-5000 m / pas, purity >95%), carboxymethyl cellulose (CMC, 1% viscosity 100-2000 m / pas, purity >95%), lithium magnesium silicate (purity >99%), super absorbent polymer (SAP, 200-400 mesh, water absorption rate <40s, purity >99%), γ-polyglutamic acid (γ-PGA, molecular weight 1.2 million, purity >99%), and carbomer Ultrez20 (U20, 1% viscosity 47000-77000 m / pas, purity >99%) were purchased from Guangzhou Baiyu Biotechnology Co., Ltd.

[0042] Example 1

[0043] This example analyzes the solubility and transparency of various commonly used gels and observes the gelling properties to screen gel materials that meet the requirements of a semi-solid gel state, high transparency, low strength and weak adhesion, but with good supporting capacity.

[0044] 1. Experimental Materials:

[0045] (1) Food gels: gellan gum, locust bean gum, agar powder, xanthan gum, carrageenan and artemisia seed gum.

[0046] (2) Industrial gels: Hydroxyethyl cellulose (HHR-250), carboxymethyl cellulose (CMC), lithium magnesium silicate, super absorbent polymer (SAP), γ-polyglutamic acid (γ-PGA) and carbomer Ultrez20 (U20).

[0047] 2. Experimental setup: This experiment set up 36 treatments, which were 0.4%, 0.8% and 1.2% concentration solutions of the above 12 food gels and industrial gels, and each treatment was set up with 3 replicates.

[0048] 3. Experimental Procedure: Weigh 0.2, 0.4, and 0.6 g of gellan gum (high acyl), locust bean gum, agar powder, xanthan gum, carrageenan, artemisia seed gum, HHR-250, CMC, lithium magnesium silicate, SAP, γ-PGA, and carbomer U20, respectively, place in a 100 mL beaker, add 50 mL of deionized water, stir and dissolve for 1 minute, let stand for 5 minutes, and obtain gel solutions with concentrations of 0.4%, 0.8%, and 1.2% by mass. Observe and record the dissolution and gelation. Then, place in a 65°C water bath, stir and dissolve for 20 minutes, let stand and cool, and continue to observe and record the dissolution and gelation. Laser penetration was also measured.

[0049] 4. Experimental results: In the food gel, 0.4% locust bean gum, 0.4% agar powder, 0.4% carrageenan, 0.8% carrageenan, 1.2% carrageenan, 0.4% artemisia seed gum, 0.8% artemisia seed gum, and 1.2% artemisia seed gum had good solubility when mixed alone, and the solutions were semi-solid gels with transparency. In the industrial gel, except for 1.2% CMC, 0.4% γ-PGA, and 1.2% γ-PGA, the gel solutions at other experimental concentrations were semi-solid gels with transparency. The above transparent gels can be used for the next step of stability analysis experiments.

[0050] Table 1 Solubility, transparency and gelling properties of food gels

[0051]

[0052] Table 2 Solubility, transparency and gelling properties of industrial gels

[0053]

[0054] Example 2

[0055] This example is based on the gel materials screened in Example 1, and further tests are conducted to determine the stability and antiseptic and antibacterial capabilities of these gels when compounded with nutrient solutions.

[0056] The experimental materials are the same as those in Example 1.

[0057] Implementation process: First, prepare 1 / 4 Hoagland's nutrient solution. Then, weigh 0.2g each of gellan gum, locust bean gum, agar powder, xanthan gum, carrageenan, artemisia seed gum, HHR-250, CMC, lithium magnesium silicate, SAP, γ-PGA, and carbomer U20 and place them in a 100mL beaker. Add 1 / 4 Hoagland's nutrient solution to each beaker containing the gel, adding 50mL to each beaker and stirring thoroughly. Then, heat and stir on a hot plate to dissolve (be sure to stir thoroughly to prevent overheating and charring). Let cool and solidify. Then, store at room temperature for one week, observing and recording any flocculation and mold formation.

[0058] Experimental results: Analysis of the stability of various gel-blended nutrient solutions ( Figure 1 ) learned that Figure 1 The food-grade glues in the first row generally showed mold and yellowing after being stored for a period of time. Gellan gum showed the most severe color change, but mild fungal growth. Agar powder showed more severe color change, with the solution changing from transparent to opaque. Carrageenan and locust bean gum solutions showed less color change than the other four solutions, but still showed visible mycelial colonies. Figure 1 The industrial glues in the second row all showed stratification after being left for a period of time. Specifically, the upper layer of the solution was an opaque, turbid, semi-solid texture, while the lower layer of the solution was a transparent, yellowish, thinner liquid texture. The lithium magnesium silicate gel solution showed less stratification, with little difference between the upper and lower layers. The upper and lower layers of the CMC, carbomer, SAP, and γ-PGA gel solutions showed significant differences. The HHR-250 gel solution showed less stratification, but exhibited slight bacterial growth. It can be seen that after the gel solution was prepared and allowed to stand for a period of time, food-grade glue gel solutions generally showed bacterial growth and yellowing problems. Industrial-grade glue gel solutions were unstable when prepared alone, and generally showed stratification and hydration.

[0059] Example 3

[0060] Based on the results of Example 1 and Example 2, this example attempts to apply existing antiseptic methods to solve the problem of bacterial growth and mildew in food gels.

[0061] 1. Experimental Materials: Based on the results of Example 1, carrageenan and artemisia seed gum were selected to carry out this experiment; the nutrient solution was 1 / 4 Hoagland's nutrient solution; and the preservatives were potassium sorbate and tea polyphenols commonly used in the industry, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0062] 2. Experimental Design and Procedure

[0063] As shown in Table 3, 9 treatments were set up, with 3 replicates for each treatment. Treatment setting instructions: (1) Different glue addition treatments were used to test the stability of the glue and its effect on plant growth; (2) Treatments with preservatives and without preservatives were used to test the antibacterial effect and its effect on plant growth. First, prepare 1 / 4 Hoagland's nutrient solution, then weigh carrageenan and Artemisia seed gum according to Table 3 and place them in a 100mL beaker; add 1 / 4 Hoagland's nutrient solution to the beakers containing the gel, adding 50mL to each beaker and stirring thoroughly. Then place on a heating plate and heat to 80℃ and stir to dissolve (note that stirring should be done in time to prevent some parts from being overheated and coking). Let it stand and cool to solidify to obtain a semi-gel. Transplant 5-day-old corn seedlings that have been sterilized into the semi-gel prepared above. For the preservative addition treatment, add 2-5mL (about 5mm thick) of 0.1% potassium sorbate or 0.05% tea polyphenols solution layer on the glue surface. Cover the culture cup with a light-shielding film. After one week of cultivation, the growth of corn was observed.

[0064] Table 3 Preservative safety analysis and processing settings

[0065]

[0066]

[0067] 3. Experimental results: Analysis of the safety of adding preservatives to food gels ( Figure 2 ) It was found that when corn seedlings were cultured with food gel solution + preservative solution, the growth state of the corn seedlings was poor. The corn seedlings of P1, P4, P6, and P7 all died, and the corn seedlings of P3 and P5 partially died. The corn seedlings of P2, P8, and P9 survived, but the solution was severely hydrated and the bacterial growth was obvious, making it impossible to effectively observe the plant roots. The bacterial growth of the gel did not improve significantly after the addition of preservatives, but the addition of preservatives had a huge impact on the plants. This shows that although food gels can meet the requirements of semi-solid gel state, high transparency, low strength and weak adhesion but good supporting capacity, they have poor antiseptic and antibacterial capabilities and cannot be improved by commonly used antiseptic methods, and cannot meet the requirements of use in open environments.

[0068] Example 4

[0069] Based on the results of Example 1 and Example 2, this example attempts to solve the stability problem of industrial gel compounding through a compounding method, further explores methods to improve gel stability and antiseptic and antibacterial capabilities, and optimizes the semi-solid gel preparation method.

[0070] 1. Experimental Materials: Based on the results of Example 1, lithium magnesium silicate, CMC, HHR-250, SAP, carbomer U20, and γ-PGA were compounded; the nutrient solution was 1 / 4 Hoagland's nutrient solution.

[0071] 2. Experimental Design and Procedure

[0072] Six treatments were set up as shown in Table 4. First, prepare 1 / 4 Hoagland's nutrient solution. Then, weigh lithium magnesium silicate, CMC, HHR-250, SAP, carbomer U20, and γ-PGA according to Table 3 and place them in 100mL beakers. Add 1 / 4 Hoagland's nutrient solution to each beaker containing the gel, adding 50mL to each beaker. Dissolve the gel in an 80°C water bath at 300 rpm with rapid stirring. Allow to cool and solidify. Observe the basic morphology of the gel and record the gel formulation stability.

[0073] Considering that some gels generate a large number of bubbles after compounding, further defoaming treatment is required, including microwave or ultrasonic oscillation (Xinzhi SB25-12DTD ultrasonic cleaning machine, frequency 20 kHz, ultrasonic time adjusted based on defoaming effectiveness) and changing the order of gel mixing. After obtaining a bubble-free gel, sterilized five-day-old corn seedlings were transplanted into the semi-gel. The culture cup was covered with light-shielding film. After one week of culture, the corn growth was observed and the safety of the gel compound was analyzed.

[0074] Table 4 Industrial gel compounding treatment settings

[0075] Processing number illustrate F1 0.6% lithium magnesium silicate + 0.8% CMC F2 0.6% lithium magnesium silicate + 0.8% HHR-250 F3 0.6% lithium magnesium silicate + 0.5% SAP F4 0.5% γ-PGA + 0.5% Carbomer U20 F5 0.5%γ-PGA+0.3%SAP F6 0.5% Carbomer U20 + 0.3% SAP

[0076] 3. Experimental results: Analysis of the stability of industrial gel compounding ( Figure 3 ) showed that the texture of the industrial gel was significantly improved after compounding. After standing for a period of time, the texture of the gel solution was similar to that of the initial solution, with both solutions showing a semi-solid texture. The gel solution was transparent and showed no stratification. However, the F2 and F5 solutions contained numerous bubbles, resulting in opacity. In F1, F3, and F4, bubbles were significantly more abundant in the upper layer of the gel than in the lower layer, while the F6 solution contained fewer bubbles. This suggests that rapid stirring and dissolution can easily lead to bubble formation, affecting subsequent root observation.

[0077] Analysis of industrial gel compounding safety (such as Figure 4) It can be seen that corn seedlings grew well in various industrial gel compound solutions. The gel solution was transparent and semi-solid, and the growth of the corn seedling roots could be clearly observed. In contrast, the corn plants and roots grew better in the F6 treatment (0.5% Carbomer U20 + 0.3% SAP), as shown by the growth of more new roots, which were better expanded in the gel, and a more natural root structure was obtained. This meets the basic requirements of simulating root growth in a natural state. Therefore, the subsequent carbomer U20 and SAP ratio was mainly selected for plant growth determination.

[0078] Example 5

[0079] Based on the results of Example 4, this example further selected different concentrations of Carbomer U20 and SAP for compounding, analyzed the gel state of the two colloid compounds and the tolerance of corn seedlings, and screened the appropriate semi-gel ratio.

[0080] 1. Experimental materials: Carbomer U20 and SAP were mixed; the nutrient solution was 1 / 4 Hoagland's nutrient solution.

[0081] 2. Experimental Design and Procedure

[0082] Four concentration levels of Carbomer U20 and SAP were set, wherein the concentration levels of Carbomer U20 were 0.1%, 0.2%, 0.5% and 0.8% by mass, and the concentration levels of SAP were 0.05%, 0.15%, 0.3% and 0.4% by mass, and then L16(4 2 ) Orthogonal design, with 16 treatments in total. The experimental process was the same as in Example 4.

[0083] Table 5 Carbopol U20 and SAP compound L16 (4 2 ) Orthogonal design processing settings

[0084] Processing number Kaboom U20 SAP t1 0.1％ 0.05％ t2 0.1％ 0.15％ t3 0.1％ 0.3％ t4 0.1％ 0.4％ t5 0.2％ 0.05％ t6 0.2％ 0.15％ t7 0.2％ 0.3％ t8 0.2％ 0.4％ t9 0.5％ 0.05％ t10 0.5％ 0.15％ t11 0.5％ 0.3％ t12 0.5％ 0.4％ t13 0.8％ 0.05％ t14 0.8％ 0.15％ t15 0.8％ 0.3％ t16 0.8％ 0.4％

[0085] 3. Experimental Results: Analysis of the gelation state of the two gels and the tolerance of corn seedlings (Table 6) showed that when the Carbomer U20 dosage was less than 0.2% (0.1%), the gelation state was unstable, while when the dosage exceeded 0.5% (0.8%), it tended to become overly viscous. Neither state was ideal for a semi-gel state. When the SAP dosage exceeded 0.3%, it easily caused osmotic stress to the corn, causing it to wilt. Based on the gelation state of the two gels and the tolerance of corn seedlings, it was found that the combined concentrations of the two gels should be controlled at: 0.2% to 0.5% for Carbomer U20 and 0.05% to 0.3% for SAP.

[0086] Table 6 Gelation status of carbomer U20 and SAP and tolerance of corn seedlings

[0087]

[0088]

[0089] Example 6

[0090] Based on the results of Examples 4 and 5, this example uses the garden herb Colocasia esculenta as the plant object to compare and analyze the growth, root morphology changes, and nutrient absorption differences of Colocasia esculenta in nutrient solution and different semi-gel formulas, verify the safety and feasibility of using semi-solid gel formulas to observe and analyze the growth of herb seedlings, and improve the establishment of a semi-solid gel culture method for plant roots.

[0091] 1. Experimental Materials: The test plants were three-month-old seedlings of the fast-growing herb Alocasia longiloba, purchased from the Guangzhou Fangcun Nursery Wholesale Market. The test medium consisted of a semi-solid gel medium and nutrient solution. The semi-gel medium consisted of a polymer absorbent polymer (SAP) and carbomer U20 (U20); the nutrient solution was 1 / 4 Hoagland's nutrient solution. The test container was a fully transparent root box constructed from non-toxic polypropylene panels, measuring 20 cm × 10 cm × 5 cm.

[0092] 2. Experimental process:

[0093] (1) Gel formulation: The experiment used 1 / 4 Hoagland's nutrient solution as the control treatment (CK), U20 and SAP as the test gels, and set up four semi-solid gel treatment formulations:

[0094] T1, SAP with a final concentration of 0.3% by mass was dissolved in 1 / 4 Hoagland's nutrient solution;

[0095] T2, U20 with a final concentration of 0.5% by mass was dissolved in 1 / 4 Hoagland's nutrient solution;

[0096] T3, U20 with a final concentration of 0.4% by mass and SAP with a final concentration of 0.3% by mass were dissolved in 1 / 4 Hoagland's nutrient solution;

[0097] T4, U20 with a final concentration of 0.5% by mass and SAP with a final concentration of 0.2% by mass were dissolved in 1 / 4 Hoagland's nutrient solution.

[0098] Each treatment had 4 root boxes, and each root box was a replicate.

[0099] (2) Preparation of semi-solid gel: First, prepare 1 / 4 Hoagland's nutrient solution (pH 6.0), then heat it to 80℃ in a water bath. According to the treatment settings, weigh the corresponding mass of SAP and U20 into the nutrient solution, and stir and dissolve them in an 80℃ water bath. Among them, T1 and T2 are stirred and dissolved at 300 rpm, and the dissolution time is about 4 minutes. T3 is to add SAP and U20 at the same time, and stir and dissolve them at 30 rpm, and the dissolution time is about 35 minutes. T4 is to first weigh carbomer U20 into the nutrient solution preheated in an 80℃ water bath, and stir and dissolve it at 300 rpm in an 80℃ water bath for 3 minutes; then weigh SAP into the carbomer U20 nutrient solution, and stir and dissolve it at 30 rpm in an 80℃ water bath for 35 minutes.

[0100] (3) In situ non-destructive observation and sampling analysis of plant root growth: The dissolved gel was transferred to a root box, 800 mL per root box. If bubbles appeared, the root box was placed in an ultrasonic cleaner (Xinzhi SB25-12DTD ultrasonic cleaner, frequency 20KHz, ultrasonic time was adjusted according to the defoaming effect) for ultrasonic defoaming. After the gel was left to cool to room temperature, the plant was transplanted into the root box and fixed with a sponge (by fixing the stem of the aboveground part with a sponge), and the roots were properly dispersed so that they were evenly distributed in the culture matrix. During the growth period, root growth images of the front of the root box were collected by a portable scanner every 7 days, and then the changes in root length and root surface area were analyzed with the help of WinRHIZO Pro 2017. After 5 weeks of growth, the roots and semi-solid gel were poured into water, and the complete root system was obtained by rinsing. The aboveground part and the root system were separated, and the biomass, aboveground part and root nitrogen, phosphorus and potassium were measured.

[0101] Example 7

[0102] Based on the results of Examples 4 and 5, this example uses the shrub plant Schefflera chinensis as the plant object to compare and analyze the differences in Schefflera chinensis growth, root morphology changes, and nutrient absorption in nutrient solution and different semi-gel formulas, verify the safety and feasibility of using semi-solid gel formulas to observe and analyze the growth of shrub plant seedlings, and improve the establishment of a semi-solid gel culture method for plant roots.

[0103] 1. Experimental Materials: The test plants were 3-month-old seedlings of the slow-growing shrub Schefflera actinopylla, purchased from the Guangzhou Fangcun Nursery Wholesale Market. Other experimental materials were the same as in Example 6.

[0104] 2. The experimental process is the same as Example 6.

[0105] The results of Example 6 and Example 7 are as follows:

[0106] (1) Changes in gel morphology and root growth

[0107] After 5 weeks of storage, no mold or bacterial growth was observed in the culture media of each treatment; 0.3% SAP gel nutrient solution (T1) and 0.4% U20 + 0.3% SAP gel nutrient solution (T3) showed a certain degree of hydration and stratification, and the bottom gel was turbid; 0.5% U20 gel nutrient solution (T2) showed more serious hydration and stratification, and obvious flocculent precipitation appeared in the bottom; 0.5% U20 + 0.2% SAP gel nutrient solution (T4) was relatively stable and as clear and transparent as 1 / 4 Hoagland's nutrient solution (CK) ( Figure 5 ). The root system of Schefflera chinensis grew relatively slowly. Except for T1, a certain number of new white roots were observed in other treatments. The root system of Colocasia nigra grew relatively fast. A certain number of new white roots were observed in different treatments, and the number was greater than that of Schefflera chinensis. Compared with CK, both T1 and T2 inhibited the root growth of Schefflera chinensis and Colocasia nigra. It is worth noting that in CK, the roots of the two plants were not easy to stretch and mostly drooped in the nutrient solution; the difference is that in T4, the roots stretched more naturally in the semi-solid gel, and the lateral roots and fine roots were spread out at a certain angle. The above results also show that the stirring and dissolution rate and addition order of SAP and U20 also affect the stability of the gel.

[0108] (2) Changes in root morphological indicators

[0109] Dynamic observations of the root length changes of Schefflera chinensis and Colocasia nigra in different culture media (Table 7) showed that treatments T1 and T2 significantly inhibited root growth of both plants after one week of planting. By week five, the total root length of Schefflera chinensis in the T1 and T2 treatments was significantly reduced by 51.59% and 47.48%, respectively, compared with the control (CK), and the total root length of Colocasia nigra was significantly reduced by 44.72% and 45.86%, respectively, compared with the CK. There were no significant differences in total root length between Schefflera chinensis and Colocasia nigra in the T3 and T4 treatments compared with the CK.

[0110] Table 7 Changes in total root length of plants

[0111]

[0112] Note: The data in the table are the mean ± standard error of 4 replicates. Different letters after the same data indicate significant differences among different treatments at the same time (P < 0.05, Duncan).

[0113] Similar to changes in root length, treatments T1 and T2 significantly inhibited changes in root surface area in both plants after one week of planting (Table 8). By week five, the root surface area of ​​Schefflera citrifolia in the T1 and T2 treatments was significantly reduced by 30.59% and 32.27%, respectively, compared to the CK, and the root surface area of ​​Colocasia nigra was significantly reduced by 29.23% and 27.75%, respectively, compared to the CK. Compared to the CK, the root surface area of ​​Schefflera citrifolia in the T3 and T4 treatments decreased after one week of planting, but no significant differences were observed by week five. There was also no significant difference in root surface area among the three treatments (CK, T3, and T4) for Colocasia nigra at week five.

[0114] Table 8 Changes in plant root surface area

[0115]

[0116] Note: The data in the table are the mean ± standard error of 4 replicates. Different letters after the same data indicate significant differences among different treatments at the same time (P < 0.05, Duncan).

[0117] (3) Changes in plant biomass

[0118] After 5 weeks of growth, compared with CK, the fresh weight of the aboveground part and root system of Schefflera chinensis in T2 treatment was significantly reduced by 37.05% and 54.05%, and the fresh weight of the aboveground part and root system of Colocasia nigra were significantly reduced by 35.03% and 63.22%, respectively. Figure 6 ); the fresh weights of the aboveground parts and roots of the two plants in T2 and T3 treatments also decreased to a certain extent, and the decrease in T2 was greater than that in T3; the fresh weights of the aboveground parts and roots of the two plants in T4 treatment had no significant difference from those in CK.

[0119] (4) Changes in plant nutrients

[0120] After 5 weeks of growth, the nitrogen, phosphorus and potassium contents in the shoots and roots of Schefflera chinensis treated with T2 were significantly lower than those in CK. The nitrogen in the shoots and roots decreased by 28.07% and 25.29%, respectively; the phosphorus decreased by 42.82% and 25.15%, respectively; and the potassium decreased by 45.21% and 52.39%, respectively. Figure 7 ); the nitrogen, phosphorus and potassium contents in the aboveground parts and the potassium content in the roots of Schefflera chinensis treated with T1 were also significantly lower than those in CK; the nitrogen, phosphorus and potassium contents in the aboveground parts and roots of T3 and T4 treatments were not significantly different from those in CK.

[0121] After 5 weeks of growth, the nitrogen, phosphorus and potassium contents in the shoots and roots of black leaf taro in T1 and T2 treatments were significantly decreased compared with those in CK ( Figure 8), and the decrease was greater in T2. ​​The nitrogen in the aboveground part and root system of black leaf taro under T2 treatment decreased by 21.76% and 34.19%, the phosphorus decreased by 62.52% and 25.15%, and the potassium decreased by 40.15% and 27.24%, respectively. There were no significant differences in the nitrogen, phosphorus and potassium contents in the aboveground part and root system of T3 and T4 treatments compared with CK.

[0122] Example 8

[0123] This example is based on the results of Examples 4 and 5. Taking the inflorescence of an arbor plant as the plant object, the growth of the inflorescence, root morphology changes and nutrient absorption differences in nutrient solution and different semi-gel formulas are compared and analyzed, the safety and feasibility of using semi-solid gel formulas to observe and analyze the growth of arbor plant seedlings are verified, and a complete semi-solid gel culture method for plant roots is established.

[0124] 1. Experimental Materials: 4-month-old tissue culture seedlings of Neolamarckia cadamba were provided by Professor Chen Xiaoyang's team at the College of Forestry and Landscape Architecture, South China Agricultural University. Other experimental materials were the same as those in Example 6.

[0125] 2. Experimental Procedure: 1 / 4 Hoagland's nutrient solution served as the control (CK) and U20 and SAP served as test gels. Two semi-solid gel formulations were developed: T1: 0.4% U20 + 0.3% SAP dissolved in 1 / 4 Hoagland's nutrient solution; T2: 0.5% U20 + 0.2% SAP dissolved in 1 / 4 Hoagland's nutrient solution. Each treatment consisted of four rhizoboxes, with each rhizobox serving as a replicate. The semi-solid gels were prepared as follows: T1: SAP and U20 were added simultaneously and dissolved with slow stirring at 30 rpm for approximately 35 minutes. T2: U20 was first weighed and dissolved in the nutrient solution preheated at 80°C in a waterbath at 300 rpm for 3 minutes. SAP was then weighed and dissolved in the U20 nutrient solution with slow stirring at 30 rpm for 35 minutes. In situ non-destructive plant root growth observation and sampling analysis are the same as in Example 6.

[0126] 3. Results

[0127] (1) Differences in flower biomass in different formulations of glue

[0128] The analysis showed that there were no significant differences in plant height, ground diameter, aboveground fresh weight and root fresh weight among the four biomasses of the nutrient solution CK group, gel compound group 1 T1 and gel compound group 2 T2 ( Figure 9 ).

[0129] (2) Differences in root morphology of flower clusters in different formulations of glue

[0130] Analysis of the root morphological differences of cluster flowers ( Figure 10 ) showed that the total root length of the two compound gel solution T1 and T2 groups was longer than that of the nutrient solution CK group. The total root length of the three groups increased in sequence, with a difference of about 6 cm between each group. The root surface area of ​​the T2 group was the largest, 10 cm longer than that of the CK group. 2 CK group was slightly higher than T1 group by about 2.5cm 2 The root volume of the T2 group was the highest, 1.8 cm higher than that of the CK group. 3 The root diameter of the CK group was the longest, approximately 0.5 mm longer than the other two groups, and the root diameter of T2 was slightly higher than that of T1. There were no significant differences in total root length, root surface area, root volume, and root diameter between the CK group, the gel-based compound group (T1), and the gel-based compound group (T2). This suggests that, compared to the nutrient solution, the semi-solid gel did not significantly affect the root morphology of the floret.

[0131] (3) Differences in nutrients between the aboveground part and root system of the flower in different formulations of glue

[0132] Analysis of nitrogen, phosphorus and potassium contents in the aboveground part and root system of the flower Figure 11 ) showed that the nitrogen content in the aboveground parts of the T1 and T2 groups of the buds was higher than that in the nutrient solution group CK, with the T1 group higher than the T2 group. The nitrogen content in the aboveground parts of the three groups showed an increasing trend, with a difference of approximately 0.1% between each group. The root nitrogen content of the T1 group was the highest, 0.05% higher than that of the T2 group, and 0.025% higher than that of the CK group. The phosphorus content in the aboveground parts of the T2 group was the highest, about 0.25% higher than that of the other two groups, and the T1 group was slightly lower than the CK group. The root phosphorus content of the T2 group was the highest, followed by the CK group, and the root phosphorus content of the T1 group was the lowest, with a difference of approximately 0.3% between each group. The difference in potassium between the aboveground and root parts was smaller. There was no significant difference in the nitrogen, phosphorus, and potassium content between the CK and T1 and T2 groups in either the aboveground or root parts. It can be seen that compared with the nutrient solution, the semi-solid gel did not significantly affect the absorption of nitrogen, phosphorus, and potassium nutrients by the aboveground parts and roots of the buds.

[0133] The results of Examples 6, 7 and 8 above show that high-concentration SAP fast single-mix gel, high-concentration U20 fast single-mix gel and 0.4% U20 + 0.3% SAP slow-mix gel will hydrate or flocculate and stratify after long-term storage. The 0.5% U20+0.2% SAP gel mixed sequentially according to the method of Example 6 was as stable and clear as 1 / 4 Hoagland's nutrient solution; high-concentration SAP and high-concentration U20 gel inhibited the root growth, nutrient absorption and biomass accumulation of Schefflera chinensis and Colocasia nigra, which was detrimental to plant growth; although the root growth, nutrient absorption and biomass accumulation of the herbaceous plant Colocasia nigra, the shrub Schefflera chinensis and the tree Colocasia glomerata seedlings in the 0.4% U20+0.3% SAP gel mixed simultaneously with slow mixing and the 0.5% U20+0.2% SAP gel mixed sequentially according to the method of Example 6 were not significantly different from those in the CK, indicating that they were relatively safe for plant growth, the 0.4% U20+0.3% SAP gel mixed simultaneously with slow mixing had poor stability, while the 0.5% U20+0.2% SAP gel mixed sequentially according to the method of Example 6 had good stability.

Claims

1. A method for preparing a semi-solid gel for observing plant root growth, characterized in that: The following steps are involved: 100 parts by mass of plant nutrient solution is prepared, heated to 65-80° C., 0.2-0.5 parts by mass of Carbomer U20 is added, and the solution is stirred at 200-400 revolutions per minute under heat preservation conditions until the solution is fully dissolved. Then, 0.05-0.3 parts by mass of a high-molecular-weight water-absorbing resin is added, and the solution is stirred at 20-50 revolutions per minute under heat preservation conditions until the solution is fully dissolved. If bubbles appear, they are eliminated by ultrasound. Thus, a semi-solid gel is prepared.

2. The preparation method according to claim 1, characterized in that The plant nutrient solution is Hoagland's nutrient solution, MS nutrient solution, Yamazaki nutrient solution or horticultural balanced nutrient solution.

3. The preparation method according to claim 1, characterized in that The method comprises the following steps: preparing 100 parts by mass of plant nutrient solution, heating the solution to 80° C., adding 0.5 parts by mass of carbomer U20, stirring the solution at 300 revolutions per minute under heat preservation conditions until the solution is fully dissolved, then adding 0.2 parts by mass of a high-molecular-weight water-absorbing resin, stirring the solution at 30 revolutions per minute under heat preservation conditions until the solution is fully dissolved; if bubbles appear, eliminating the bubbles by ultrasound, thereby preparing a semi-solid gel.

4. A semi-solid gel prepared according to the method for preparing a semi-solid gel for observing plant root growth according to any one of claims 1 to 3.

5. Use of the semi-solid gel according to claim 4 in in-situ non-destructive observation of plant root growth.

6. The use according to claim 5, characterized in that The method comprises the step of utilizing the semi-solid gel as a plant culture matrix.

7. The use according to claim 6, characterized in that The following steps are involved: The semi-solid gel is placed in a transparent root box and bubbles are eliminated. The plant is then transplanted into the root box. The roots are appropriately dispersed so that the roots are naturally distributed in the semi-solid gel. The stems of the above-ground parts of the plants are fixed. The root box is wrapped with light-proof material. The plants are cultured and the growth of the plant roots is observed in due course.

8. The use according to claim 5, characterized in that The plants are herbaceous plants, shrub plants or tree plant seedlings.

9. The use according to claim 8, characterized in that The herb is Clocasia nigra, the shrub is Schefflera chinensis, and the tree is Cyperus rotundus.

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