Multi-dimensional cadmium-controlling ecological regulating agent and application thereof in rice planting in cadmium-polluted soil

Abstract

The invention belongs to the technical field of rice field cadmium pollution treatment, and particularly relates to a multi-dimensional cadmium-control ecological regulating agent and application thereof in rice planting in cadmium-polluted soil. The multi-dimensional cadmium-controlling ecological regulating agent comprises waste activated carbon containing micromolecule polypeptide, macromolecular polypeptide, molasses and a rice endophyte solution, the rice endophyte solution is rice endophytic metal-resistant cupriavidus CML2, and the volume L of the rice endophyte solution is 1-5% of the volume L of the rice endophytic metal-resistant cupriavidus CML2. The ratio of the waste activated carbon containing the micromolecule polypeptide to the macromolecular polypeptide to the molasses to the rice endophyte solution is 16: 32: 1: 1. The multi-dimensional cadmium-controlling ecological regulating agent provided by the invention can reduce cadmium in a multi-dimensional manner by means of soil in-situ passivation, micro-ecological combination, rice endophyte prevention and control, porous activated carbon adsorption and the like, so that yield increase and restoration of rice are effectively realized at the same time, and the cadmium content of the produced rice is lower than the national highest limit standard 0.2 mg / kg.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cadmium pollution treatment of paddy fields, and particularly relates to a multi-dimensional cadmium control ecological regulator and application thereof in cadmium-polluted soil and rice planting. BACKGROUND

[0002] Cadmium (Cd) is one of the harmful elements widely existing in heavy metal contaminated soil, and has a strong migration ability in the soil-crop system, thereby being enriched in the organism and entering the human body through the food chain. After entering the human body, cadmium can gradually accumulate in the liver, kidney, bone, lung and other systems, and when accumulated to a certain extent, can cause arteriosclerosis, kidney atrophy, lung organ damage and even cancer, and more seriously, can cause death.

[0003] Rice is an important food crop in China, and compared with other heavy metals, rice planted in medium and light cadmium-polluted paddy fields is extremely prone to cadmium exceeding the standard. Therefore, the treatment and safe use of rice soil polluted by medium and light cadmium is an urgent problem to be solved. At present, the methods for treating large areas of cadmium pollution in China mainly include the plant remediation method and the chemical passivation method. The former has a too long cycle and the paddy field will temporarily lose the production capacity, and the treatment technology of the latter including the precipitation passivation of phosphate and the in-situ passivation of high molecular materials will have a relatively large impact on the soil environment, and it is difficult to reach the limit concentration of the precipitation passivation for the areas with low concentration of heavy metal ions, and there is a new pollution risk in long-term application of some in-situ passivation agents. All the technologies are actually an emergency technology, and none of them has been fully popularized and applied. Therefore, it is of important practical significance to find a new simple, effective and environmentally friendly method for reducing the cadmium content in rice, and it is of great significance to the quality and safety of food and the development of green agriculture. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a multi-dimensional cadmium control ecological regulator, which can reduce cadmium in multiple dimensions through soil in-situ passivation, microecology combination, water rice endophyte control, porous activated carbon adsorption and other modes, effectively realizes the simultaneous yield increase and remediation of rice, and the cadmium content of the produced rice is lower than the national maximum limit standard 0.2 mg / kg. Therefore, the present application also provides the application of the multi-dimensional cadmium control ecological regulator. The present application is realized by the following technical solutions:

[0005] The present application provides a multi-dimensional cadmium control ecological regulator in the first aspect, which comprises waste activated carbon containing small molecule polypeptide, macromolecular polypeptide, molasses and rice endophyte solution, the rice endophyte is rice endophytic metal-tolerant Cupriavidus CML2, and the proportion of the waste activated carbon containing small molecule polypeptide, the macromolecular polypeptide, the molasses and the rice endophyte solution is 16:32:1:1 in terms of mass kg:mass kg:mass kg:volume L.

[0006] Further, the multi-dimensional cadmium control ecological regulator comprises 320 kg of waste activated carbon containing small molecule polypeptides, 640 kg of large molecule polypeptides, 20 kg of molasses, and 20 L of rice endophyte solution.

[0007] Further, the average molecular weight of the small molecule polypeptides in the waste activated carbon containing small molecule polypeptides is 200-500 Da, and the proportion is more than 10%.

[0008] Further, the average molecular weight of the large molecule polypeptides is 10,000-15,000 Da.

[0009] Further, the molasses contains more than 50% of sugar.

[0010] Further, the number of viable bacteria in the rice endophyte solution is more than 1.5 x 10 11 CFU / mL.

[0011] The second aspect of the application provides application of the multi-dimensional cadmium control ecological regulator as described above in rice planting in cadmium contaminated soil.

[0012] Further, the cadmium concentration of the cadmium contaminated soil is 0.3-0.8 mg / kg.

[0013] Further, the multi-dimensional cadmium control ecological regulator is applied to the bottom of the cadmium contaminated soil by one-time base application, and the application amount per mu is 100-150 kg.

[0014] The third aspect of the application provides a method for producing low-cadmium-content rice in cadmium contaminated soil, comprising the following steps:

[0015] S1, one-time base application of the multi-dimensional cadmium control ecological regulator as described above to the bottom of the cadmium contaminated soil;

[0016] S2, direct seeding of rice seeds in the cadmium contaminated soil to which the multi-dimensional cadmium control ecological regulator is applied, and the planting mode is a wide-narrow row and high-density planting mode, wherein the wide row spacing is 13-26 cm, the narrow row spacing is 9 cm, and the planting density is 20 x 10 4 -25 x 10 4 plants / hm 2 .

[0017] Further, the wide row spacing is 26 cm, the narrow row spacing is 9 cm, and the planting density is 20 x 10 4 plants / hm 2 .

[0018] Further, the wide row spacing is 13 cm, the narrow row spacing is 9 cm, and the planting density is 25 x 10 4 plants / hm 2 .

[0019] The advantages and positive effects of the present application are:

[0020] 1、The present application is a multi-dimensional cadmium control ecological regulator with thiol and carboxyl precipitation combination function and a large number of microbial cell surface combination, intracellular combination and adsorption, and rice conduit resistance control, which is compounded by small molecule polypeptide-containing waste activated carbon, macromolecular polypeptide, molasses and rice endophytic metal-tolerant Cupriavidus metallidurans CML2. The thiol and carboxyl chelated in the regulator can chelate cadmium ions in the soil as a precipitated state, play a chemical precipitation passivation role, the molasses as a readily available carbon source can promote the reproduction of microorganisms, improve the combination and adsorption of microorganisms, reduce the absorption of cadmium, and the addition of probiotics-rice endophytic bacteria (metal-tolerant Cupriavidus metallidurans CML2) can grow in porous carbon base and further control the transportation of cadmium ions to the upper part of rice by planting in the rice conduit, reducing the cadmium content of rice seeds. At the same time, the porous activated carbon has the function of adsorbing heavy metal cadmium ions, realizing the multi-dimensional resistance and control of cadmium absorption by rice, reducing cadmium accumulation, realizing the autonomous and safe use of medium and light cadmium contaminated soil, effectively realizing the simultaneous yield increase and repair of rice, and having a broad prospect in green and sustainable agricultural production.

[0021] 2、The multi-dimensional cadmium control ecological regulator of the present application can realize 2-2.5 times of rice intensive planting, and cooperate with the biological allocation mode of wide and narrow row intensive planting, which is beneficial to significantly reduce the absorption of cadmium ions by rice, achieve the goal of safe planting of rice in medium and light cadmium contaminated soil, and the cadmium content of the produced rice is lower than the national maximum limit standard of 0.2mg / kg.

[0022] 3、The multi-dimensional cadmium control ecological regulator of the present application can be used continuously without secondary pollution risk, which can overcome the secondary pollution problem of silicon calcium magnesium, high molecular material soil passivation agent. Moreover, the high value utilization of waste activated carbon and molasses can help the recycling of waste resources. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0024] Figure 1 The figure is a diagram of the base yellow leaf condition of rice plants in different treatment groups of the present application, wherein figures A-D are, in turn, the application of rice special fertilizer, multi-dimensional cadmium control ecological regulator, amino acid mother liquor powder compound fertilizer and nitrate nitrogen fertilizer;

[0025] Figure 2 The rice yield statistical graph of applying the multi-dimensional cadmium control ecological regulator and the amino acid nitrogen fertilizer respectively for the embodiments of the present application;

[0026] Figure 3 The rice plant physical object graph of applying the multi-dimensional cadmium control ecological regulator for the embodiments of the present application at the grain filling stage;

[0027] Figure 4 The rice plant comparison graph of applying the multi-dimensional cadmium control ecological regulator and the amino acid nitrogen fertilizer respectively for the embodiments of the present application at the mature stage. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the embodiments. The equipment and reagents used in the embodiments and test examples are commercially available unless otherwise specified. The specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0029] According to the information contained in the present application, various changes to the precise description of the present application can be easily made by those skilled in the art without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present application is not limited to the defined processes, properties or components, as these embodiments and other descriptions are merely illustrative of the specific aspects of the present application. In fact, various changes to the embodiments of the present application that are apparent to those skilled in the art or related fields are encompassed within the scope of the appended claims.

[0030] In order to better understand the present application without limiting the scope of the present application, all numbers expressing quantities, percentages, and other numerical values used in the present application are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the description and the appended claims are approximations. It will be apparent to those skilled in the art that various modifications can be made to the present application as embodied within the scope of the claims. Each of the numerical parameters recited in the specification and claims should be interpreted as being approximations and should be understood to be modified by the terms "about" and "approximately". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and the claims are approximations. Numerical parameters in the specification and claims have been determined to the best of the ability of the inventors to express the numerical values of the parameters used in the present application. Each of the numerical parameters can have a desired precision, depending on the desired properties of the application. Each of the numerical parameters can be adjusted to a higher precision as desired in certain situations. Each of the numerical parameters should be interpreted as being approximations and should be understood to be modified by the terms "about" and "approximately".

[0031] In order to make the above-mentioned objectives, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0032] Based on the current problem of rice cadmium (Cd) pollution and the important practical significance of reducing the accumulation of cadmium in rice, the present application uses waste activated carbon containing small molecule polypeptide (from decoloring activated carbon for preparing polypeptide food by enzymatic hydrolysis in food factory, containing more than 10% small molecule polypeptide with an average molecular weight of 200-500 Dalton (Da)) as a soil microbial growth adsorption carbon substrate and readily available nitrogen source (also a crop growth nitrogen source), while adding a certain proportion of a readily available carbon source that promotes soil microbial growth-sugar mill mother liquor molasses, and a long-acting nitrogen source-macromolecular polypeptide (average molecular weight 10000-15000 Da), and rice endophytic metal-tolerant Cupriavidus metallidurans CML2, to compound a multifunctional regulator with thiol and carboxyl precipitation combination functions and a large number of microbial cell surface combination, intracellular combination and adsorption, and rice conduit resistance control, which can control soil cadmium content and rice cadmium absorption from multiple dimensions. Specifically, the thiol and carboxyl in the regulator chelate cadmium ions in the soil into a precipitated state, achieving chemical precipitation passivation, delaying the absorption of cadmium ions by rice roots, while adding molasses as a readily available carbon source to provide nutrients for the rapid proliferation of soil microbial populations, accelerate the increase of microorganisms, improve the combination and adsorption of microorganisms, reduce the absorption of cadmium, in addition, the addition of probiotics-rice endophytic bacteria (metal-tolerant Cupriavidus metallidurans CML2) can grow in porous carbon and be planted in the rice conduit, further control the transport of ions to the upper part of the rice and the absorption of cadmium by the rice seed part, at the same time, the porous activated carbon has the function of adsorbing heavy metal cadmium ions, thereby controlling the absorption of cadmium by rice from multiple dimensions, improving the biosynthesis of chlorophyll and the biomass of rice under cadmium stress, reducing the accumulation of cadmium in rice plants, achieving safe use of self-government of medium and light cadmium contaminated soil, effectively realizing simultaneous yield increase and remediation of rice, and the yield of rice can be increased by more than 10%. On this basis, the biological sharing mode of wide and narrow row planting is adopted, which further reduces the absorption of cadmium ions by rice, achieves the goal of safe planting of rice in medium and light cadmium contaminated soil, and the cadmium content of the produced rice is lower than the national maximum limit standard of 0.2 mg / kg.

[0033] Based on this, an embodiment of the present application provides a multi-dimensional cadmium control ecological regulator, which comprises waste activated carbon containing small molecule polypeptide, macromolecular polypeptide, molasses and rice endophytic bacteria solution, the rice endophytic bacteria being rice endophytic metal-tolerant Cupriavidus metallidurans CML2, and the ratio of waste activated carbon containing small molecule polypeptide, macromolecular polypeptide, molasses and rice endophytic bacteria solution is 16:32:1:1 in terms of mass kg: mass kg: mass kg: volume L; that is, waste activated carbon containing small molecule polypeptide (kg): macromolecular polypeptide (kg): molasses (kg): rice endophytic bacteria solution (L)=16:32:1:1.

[0034] Optionally, the multi-dimensional cadmium control ecological regulator comprises 320 kg of waste activated carbon containing small molecule polypeptides, 640 kg of large molecule polypeptides, 20 kg of molasses, and 20 L of rice endophyte solution.

[0035] Optionally, the average molecular weight of the small molecule polypeptides in the waste activated carbon containing small molecule polypeptides is 200-500 Da, and the proportion is more than 10%.

[0036] Optionally, the average molecular weight of the large molecule polypeptides is 10,000-15,000 Da.

[0037] Optionally, the molasses contains more than 50% of sugar.

[0038] Optionally, the number of viable bacteria in the rice endophyte solution is more than 1.5 x 10 11 CFU / mL.

[0039] Another embodiment of the present application provides the use of the multi-dimensional cadmium control ecological regulator as described above in the planting of rice in cadmium contaminated soil.

[0040] The multi-dimensional cadmium control ecological regulator of the present application is particularly suitable for rice planted in light and moderate cadmium contaminated soil, wherein the cadmium concentration of the cadmium contaminated soil is 0.3-0.8 mg / kg.

[0041] The application method of the multi-dimensional cadmium control ecological regulator is one-time base application, that is, one-time application as base fertilizer, and no fertilizer can be applied except phosphorus and potassium, the multi-dimensional cadmium control ecological regulator is mixed with the soil during ploughing or buried in the bottom of the soil by ditching, and the application amount per mu is 100-150 kg.

[0042] When the multi-dimensional cadmium control ecological regulator of the present application is applied as base fertilizer, it reduces cadmium in multiple dimensions through soil in-situ passivation, micro-ecology combination, rice endophyte control, and porous activated carbon adsorption; and it helps to improve the biosynthesis of chlorophyll and the biomass of rice under cadmium stress, and provides a basis for the intensive planting of rice. Further, through the mode of wide and narrow row intensive planting of rice, the planting density per unit volume of cadmium contaminated soil is increased, cadmium is biologically distributed, the absorption of cadmium ions by single rice plant is reduced, a new technical mode of safe planting of rice in cadmium contaminated soil is formed, and the qualified demand for cadmium content in rice and rice is met.

[0043] In the wide and narrow row intensive planting of rice, the wide row spacing is 13-26 cm, the narrow row spacing is 9 cm, and the planting density is 20 x 10 4 -25 x 10 4 plants / hm 2 In a preferred embodiment, the wide row spacing is 26 cm, the narrow row spacing is 9 cm, and the planting density is 20 x 10 4 plants / hm 2Or, wide row spacing 13 cm, narrow row spacing 9 cm, planting density 25 x 10 4 plants / hm 2 .

[0044] A further embodiment of the present application provides a method for producing low-cadmium-content rice in cadmium-contaminated soil, comprising the following steps:

[0045] S1, applying the multi-dimensional cadmium control ecological regulator to the bottom of the cadmium-contaminated soil in one time as described above;

[0046] S2, live rice seeds in the cadmium-contaminated soil applied with the multi-dimensional cadmium control ecological regulator, and the planting mode is wide and narrow row planting mode, wherein the wide row spacing is 13-26 cm, the narrow row spacing is 9 cm, and the planting density is 20 x 10 4 -25 x 10 4 plants / hm 2 .

[0047] The present application will be further described below in conjunction with specific examples. The experimental methods in the following examples are not specified, and the conditions are generally in accordance with the conventional conditions, such as the conditions described in "Molecular Cloning: A Laboratory Manual (Fourth Edition)" published by Cold Spring Harbor Laboratory, or generally in accordance with the conditions recommended by the manufacturer.

[0048] 1. Preparation and use of multi-dimensional cadmium control ecological regulator

[0049] The amount of nitrogen fertilizer is determined according to the amount of nitrogen fertilizer for conventional fertilization of rice growth, the amount of polypeptide required is calculated by the nitrogen content of the polypeptide, and the multi-dimensional cadmium control ecological regulator is prepared, including: 320 kg of waste activated carbon containing small molecule polypeptide, 640 kg of macromolecular polypeptide (molecular weight 10000-15000 Da), 20 kg of molasses (containing 50% sugar) and 20 L of rice endophyte solution, and stirring uniformly.

[0050] Among them, the viable count of rice endophyte solution is 1.5 x 10 11 CFU / mL, and the rice endophyte is a rice endophytic metal-tolerant Cupriavidus metallidurans CML2 with independent intellectual property rights of the research group, which is disclosed in the patent "CN117229951A A strain of cadmium-tolerant rice endophytic metal-tolerant Cupriavidus metallidurans and its application (publication date: 2023-12-15)".

[0051] The activated carbon containing small molecule polypeptide is waste activated carbon from the factory for preparing food polypeptide (decoloring waste activated carbon after hydrolysis of acid, alkali, protease and trypsin to prepare protein polypeptide), and the polypeptide molecules are mostly small molecule polypeptides containing 2-3 amino acids (average molecular weight 200-500 daltons) after enzymolysis, and the content of small molecule polypeptide is more than 10%.

[0052] The average molecular weight of the macromolecular polypeptide is 10,000-15,000 Dalton (Da), and the preparation method thereof can refer to the method disclosed in the patent "Soil remediation agent prepared from protein peptide and method for remedying soil by using the same (ZL201210040772.9)".

[0053] 2. The multi-dimensional cadmium control ecological regulator is used as base fertilizer for rice planting in cadmium contaminated soil

[0054] The rice variety in this example is Taiyou No. 98. Before rice seeding or planting, the multi-dimensional cadmium control ecological regulator is used as base fertilizer, which is mixed with soil by plowing or buried in the bottom of soil by ditching, and the application amount is 100 kg per mu. During the rice planting period, only one fertilization is needed (except for phosphorus and potassium). The rice planting mode is as follows: the seeds are directly sowed in the field, and a biological distribution planting mode of wide and narrow rows is adopted. The row spacing of wide row is 13-26 cm, and the row spacing of narrow row is 9-18 cm. The rice plants in different rows are arranged alternately. The wide row ensures good ventilation and light conditions, and the narrow row realizes the dense planting. The planting density is 10x10 4 -30x10 4 seedlings / ha, for example, 10x10 4 seedlings / ha means that 100,000 seedlings are planted per hectare (hm 2 ). The rice planting land is cadmium contaminated soil, and the cadmium concentration is 0.3-0.8 mg / kg.

[0055] The conventional rice special fertilizer (12 kg of nitrogen per mu, ammonium nitrogen), amino acid nitrogen and nitrate nitrogen fertilizer are set as control groups. In addition, different planting densities (see Table 1) are set, which can reduce the absorption of cadmium ions by single rice plant by relatively increasing the plant density per unit volume. Phosphorus and potassium fertilizers are applied and planting management is carried out according to the conventional planting. The effects of different fertilizers combined with different planting densities on rice growth are discussed. The experimental groups are as follows:

[0056] N1: rice special fertilizer (ammonium nitrogen);

[0057] N2: multi-dimensional cadmium control ecological regulator (polypeptide nitrogen);

[0058] N3: amino acid mother liquor powder compound fertilizer (amino acid nitrogen);

[0059] N4: nitrate nitrogen fertilizer (N content 12 kg / mu (180 kg / hm 2 ), N:P:K=1:1:1);

[0060] 4 density levels (D1-D4) are shown in Table 1.

[0061] Table 1 Rice planting mode under different density treatments

[0062]

[0063] The following test data was calculated and processed using Microsoft Excel 2021 software, and statistically analyzed using IBM SPSS Statistics 26 (Chicago, IL, USA) software, and based on the least significant difference method (LSD) multiple comparison processing of mean differences. Prism8 software was used for mapping.

[0064] 3. Effect of multi-dimensional cadmium control ecological regulator on rice planting

[0065] Cadmium-containing soil (cadmium concentration 0.3-0.8 mg / kg) was collected from farmland, impurities were removed, and then naturally air-dried at room temperature, then ground and sieved to obtain the test soil. Rice potting test was carried out, using 20 cm x 20 cm (diameter x height) plastic pots, 3.0 kg of soil per pot, different treatments were set, and the treatment groups were set according to D1-4 and N1-4 above. After the rice seeds germinated and the seedlings grew, they were transplanted into pots. Routine water and fertilizer management was carried out. In different periods of rice planting, the base leaves were collected and the chlorophyll content of rice leaves was determined. The results are shown in Table 2.

[0066] Table 2 Chlorophyll content of rice leaves in different growth periods

[0067]

[0068] As can be seen from Table 2, the chlorophyll content of rice leaves increased first and then decreased during the growth process, and the chlorophyll reached a maximum value 30 days after transplanting in each treatment. Under the same nitrogen treatment, with the increase of density, the chlorophyll content of rice leaves also showed a trend of first increasing and then decreasing.

[0069] Under the same planting density but different nitrogen treatments, at planting density D1, 15 days after transplanting, the N2D1 treatment was significantly higher than the N1D1, N3D1, and N4D1 treatments, by 6.52%, 3.90%, and 4.78%, respectively. N3D1 was significantly higher than N1D1, increasing by 2.52%. At 30 days after transplanting, the N2 nitrogen treatment had the highest chlorophyll content, significantly higher than other nitrogen treatments. The N2D1 treatment increased chlorophyll content by 8.46%, 8.24%, and 19.07% compared to the N1D1, N3D1, and N4D1 treatments, respectively. 30-60 days after transplanting, the chlorophyll content of different nitrogen treatments, from highest to lowest, was N2 > N3 > N1 > N4. At 30 days post-transplanting, the chlorophyll content of the N2 nitrogen treatment increased by 8.46%, 8.24%, and 19.07% compared to the N1, N3, and N4 nitrogen treatments, respectively. At 45 days post-transplanting, the chlorophyll content of the N2 nitrogen treatment increased by 18.76%, 8.27%, and 22.56% compared to the N1, N3, and N4 nitrogen treatments, respectively. At 60 days post-transplanting, the chlorophyll content of the N2 nitrogen treatment increased by 25.16%, 9.74%, and 30.66% compared to the N1, N3, and N4 nitrogen treatments, respectively.

[0070] At planting density D2, at 30 and 45 days post-transplanting, the chlorophyll content of different nitrogen treatments, from highest to lowest, was N2 > N3 > N1 > N4. At 30 days post-transplanting, N2D2 was 9.84%, 9.35%, and 22.66% higher than N1D2, N3D2, and N4D2, respectively. At 45 days post-transplanting, N2D2 was 22.95%, 15.79%, and 31.42% higher than N1D2, N3D2, and N4D2, respectively. At 15 days post-transplanting, the N2D2 treatment was significantly higher than the N1D2 treatment, increasing by 2.75%, while the difference between the N2D2 and N3D2 treatments was not significant. Sixty days after transplanting, the N2D2 and N3D2 treatments were significantly greater than the N1D2 treatment. Compared with N1D2, the chlorophyll content of rice leaves under the N2D2 and N3D2 treatments increased by 31.81% and 19.80%, respectively.

[0071] At a planting density of D3, 15 days after transplanting, the N2D3 treatment was significantly higher than the N1D3 treatment, but there was no significant difference between the N2D3 and N3D3 treatments. The chlorophyll content in the N2D3 treatment was significantly higher than that in the N1D3 treatment by 2.96%. 30 days after transplanting, the chlorophyll content in the N2D3 treatment was significantly higher than that in other nitrogen treatments. There was no significant difference in chlorophyll content between the N3D3 and N1D3 treatments. The chlorophyll content in the N2D3 treatment increased by 6.11% and 6.68% compared to the N1D3 and N3D3 treatments, respectively. 45 days after transplanting, the N2D3 treatment showed significantly higher chlorophyll content than other nitrogen treatments, increasing by 19.70%, 11.75%, and 19.81% compared to N1D3, N3D3, and N4D3, respectively. The N3D3 treatment also showed a significant increase of 0.69% compared to the N1D3 treatment. 60 days after transplanting, the N2D3 treatment exhibited the highest chlorophyll content, significantly higher than other nitrogen treatments. The N2D3 treatment showed an increase of 27.24%, 9.89%, and 25.45% in chlorophyll content compared to the N1D3, N3D3, and N4D3 treatments, respectively.

[0072] At a planting density of D4, at 45 and 60 days post-transplanting, the chlorophyll content under different nitrogen treatments, from highest to lowest, was N2 > N3 > N1 > N4. At 15 and 30 days post-transplanting, the chlorophyll content under different nitrogen treatments, from highest to lowest, was N2 > N1 > N3 > N4. At 15 days post-transplanting, there were no significant differences among the N1, N2, and N3 nitrogen treatments, while the chlorophyll content of the N1D4, N2D4, and N3D4 treatments increased by 5.28%, 6.16%, and 4.25% compared to the N4D4 treatment, respectively. At 30 days post-transplanting, there were no significant differences in chlorophyll content between the N1D4 and N3D4 treatments, while the N2D4 treatment increased by 5.80%, 6.36%, and 17.07% compared to the N1D4, N3D4, and N4D4 treatments, respectively. At 45 days post-transplanting, the N2D4 treatment showed significantly higher chlorophyll content than the N1D4, N3D4, and N4D4 treatments, increasing by 20.66%, 14.68%, and 25.38%, respectively. There were no significant differences between the N3D4, N4D4, and N1D4 treatments. At 60 days post-transplanting, the N2D4 treatment showed an average chlorophyll content increase of 11.17%, 30.63%, and 33.77% compared to the N3D4, N1D4, and N4D4 treatments, respectively.

[0073] The chlorophyll content indicates that the multidimensional cadmium-controlling ecological regulator containing polypeptide nitrogen can significantly increase the chlorophyll content of rice. Increasing the chlorophyll content is beneficial for dense planting and increasing yield, thereby achieving the goal of cadmium biodistribution and ecological control of cadmium content in rice.

[0074] After rice matured, samples were collected, weighed to obtain rice yield, and parameters such as panicle number, effective panicle number, seed setting rate, and thousand-grain weight were recorded to explore the effects of different nitrogen levels on rice yield and its components at different planting densities. The results are shown in Table 3.

[0075] Table 3. Effects of different nitrogen elements on rice yield and yield components at different planting densities.

[0076]

[0077] As shown in Table 3, the fresh weight yield of rice per unit area gradually increases with the increase of planting density. Except for the N1 nitrogen treatment which reaches the maximum value at density D4, the fresh weight yield of rice in the N2, N3, and N4 treatments all reach the maximum at density D3. Compared with the N1D1 treatment, the average fresh weight yields of the N1D2, N1D3, and N1D4 treatments increased by 46.78%, 52.48%, and 65.14%, respectively; compared with the N2D1 treatment, the average fresh weight yields of the N2D2, N2D3, and N2D4 treatments increased by 16.46%, 62.43%, and 37.19%, respectively; compared with the N3D1 treatment, the average fresh weight yields of the N3D2, N3D3, and N3D4 treatments increased by 60.42%, 107.10%, and 45.19%, respectively; and compared with the N4D1 treatment, the average fresh weight yields of the N4D2, N4D3, and N4D4 treatments increased by 10.73%, 88.41%, and 62.88%, respectively.

[0078] Under the same density but different nitrogen treatments, the fresh weight yield of rice under different nitrogen treatments, in descending order, was N2>N3>N4>N1 under the D1 density treatment; N3>N2>N1>N4 under the D2 density treatment; N3>N2>N4>N1 under the D3 density treatment; and N2>N1>N4>N3 under the D4 density treatment. At D1 density, N2D1 treatment increased fresh weight yield by 29.28% compared to N1D1 treatment, and N3D1 treatment increased yield by 8.31% compared to N1D1 treatment; at D2 density, N2D2 treatment increased yield by 2.84% compared to N1D2 treatment, and N3D2 treatment increased yield by 18.69% compared to N1D2 treatment; at D3 density, N2D3 treatment increased yield by 37.71% compared to N1D3 treatment, and N3D3 treatment increased yield by 47.11% compared to N1D3 treatment; at D4 density, N2D4 treatment increased fresh weight yield by 7.40% compared to N1D4 treatment.

[0079] As the planting density increased, the number of rice panicles also gradually increased, reaching its maximum at density D4. However, the number of effective panicles at density D4 was lower in all nitrogen treatments than in treatment D3. Compared to treatment N1D1, treatments N1D2, N2D2, and N3D2 increased the number of panicles by 45.38%, 27.73%, and 60.09%, respectively. Treatments N1D3, N2D3, and N3D3 increased the number of panicles compared to treatment N1D1 by 79.84%, 54.20%, and 57.57%, respectively. There was no significant difference in the average number of panicles between treatments N1D2 and N3D2, but the number of effective panicles increased by 25.13% in N3D2 compared to N1D2. Treatment N2D2 had 12.14% fewer panicles than N1D2, but its number of effective panicles increased by 5.50%. The N1D3 treatment had an average spike number that was 16.63%, 14.14%, and 7.27% higher than the N2D3, N3D3, and N4D3 treatments, respectively, but the number of effective spikes was 7.27%, 10.35%, and 9.18% lower than the N2D3, N3D3, and N4D3 treatments, respectively. Overall, the N2 treatment group had a higher number of effective spikes, seed setting rate, and thousand-grain weight.

[0080] The above pot experiment shows that the application of the multidimensional cadmium-controlling ecological regulator of this invention, combined with a planting density of 2-2.5 times, can achieve the goal of increasing yield and can be demonstrated and promoted in the field.

[0081] 4. Effects of multidimensional cadmium-controlling ecological regulators on yield and cadmium control in field rice

[0082] The rice variety used in this embodiment is Taiyou 98. Before sowing or transplanting, a multi-dimensional cadmium-controlled ecological regulator (D2) is applied as a base fertilizer, mixed with the soil during tilling or buried in the bottom of the paddy soil in furrows, at a rate of 100 kg per mu (approximately 667 square meters). During the rice growing cycle, only one additional fertilizer application is needed (except for phosphorus and potassium). Rice planting method: Seeds are directly sown in the field, using a wide-narrow row dense planting pattern. The wide row spacing is 26 cm, and the narrow row spacing is 9 cm. Rice plants in different rows are arranged alternately, with a planting density of 20 × 10⁶ plants per mu (approximately 10 square meters). 4 Seedlings / ha. Amino acid mother liquor compound fertilizer (amino acid nitrogen) and rice-specific fertilizer served as control groups (CK).

[0083] After the rice matures, the rice yield is measured by sampling. Figure 2 The effects of different nitrogen elements on rice yield in field paddy fields are shown. The horizontal axis represents the treatment groups, D2 represents the multidimensional cadmium-controlled ecological regulator (peptide nitrogen), and A2 represents amino acid nitrogen fertilizer. The vertical axis represents rice yield. It is evident that the rice yields in the multidimensional cadmium-controlled ecological regulator treatment group and the amino acid nitrogen fertilizer treatment group were significantly higher than the control (CK), with average yield increases of 62.32% and 38.72%, respectively. Compared to the amino acid nitrogen fertilizer treatment group, the multidimensional cadmium-controlled ecological regulator treatment group showed a 23.6% increase in rice yield.

[0084] Figures 3-4 The image shows rice plants at the grain-filling and maturity stages. Figure 4 It can be seen that the ecological regulator containing peptide nitrogen has a higher chlorophyll content, a more obvious green color, higher density and more ears of grain, while conventional planting results in yellow leaves and a relatively shorter growing period. The peptide cadmium control regulator is usually harvested 15-20 days later than conventional planting, and the yield is significantly increased.

[0085] Cadmium content was determined in 200g samples of rice seeds from different batches harvested in Huangshi and Lichuan. The determination was commissioned to the Hubei Academy of Agricultural Sciences (Food Quality Supervision and Testing Center, Ministry of Agriculture and Rural Affairs). A PinAAcle 900T atomic absorption spectrometer was used, and the cadmium (Cd) determination method followed the first method, atomic absorption spectrometry, in the national food safety standard GB 5009.15-2023, "Determination of Cadmium in Food". The results are shown in Table 4, where group T1 represents the multidimensional cadmium-controlling ecological regulator of this invention, and group CK represents the rice-specific fertilizer group.

[0086] Table 4. Effects of different nitrogen elements on cadmium content in rice seeds (mg / kg)

[0087]

[0088] The above test results show that the CK control was unqualified, while the cadmium content in the experimental group T1 was all below 0.2 mg / kg, which meets the national food safety limit standard.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-dimensional cadmium control ecological regulator, characterized in that, The waste activated carbon containing small molecule polypeptide, the macromolecular polypeptide, the molasses and the rice endophyte solution, the rice endophyte is metal-tolerant cupriavidus CML2, according to the mass kg: mass kg: mass kg: volume L, the ratio of the waste activated carbon containing small molecule polypeptide, the macromolecular polypeptide, the molasses and the rice endophyte solution is 16:32:1:

1.

2. The multi-dimensional cadmium-controlling ecological regulator according to claim 1, characterized in that, The multi-dimensional cadmium control ecological regulator includes waste activated carbon containing small molecule polypeptide 320 kg, macromolecular polypeptide 640 kg, molasses 20 kg and rice endophyte solution 20 L.

3. The multi-dimensional cadmium-controlling ecological regulator according to claim 1, characterized in that, The average molecular weight of the small molecule polypeptide in the waste activated carbon containing small molecule polypeptide is 200-500 Da, and the proportion is more than 10%.

4. The multi-dimensional cadmium-controlling ecological regulator according to claim 1, characterized in that, The average molecular weight of the macromolecular polypeptide is 10000-15000 Da.

5. The multi-dimensional cadmium-controlling ecological regulator according to claim 1, characterized in that, The molasses contains more than 50% of sugar.

6. The multi-dimensional cadmium-controlling ecological regulator according to claim 1, characterized in that, The number of viable bacteria in the endophyte solution of the rice is above 1.5 x 10 11 CFU / mL.

7. The multi-dimensional cadmium control ecological regulator according to any one of claims 1-6 is applied to the planting of rice in cadmium contaminated soil.

8. The application of the multi-dimensional cadmium-controlling ecological regulator of claim 7 in the cadmium-contaminated soil rice planting, characterized in that, The cadmium concentration of the cadmium contaminated soil is 0.3-0.8 mg / kg; The multi-dimensional cadmium control ecological regulator is applied to the bottom of the cadmium contaminated soil by one-time base application, and the application amount per mu is 100-150 kg.

9. A method for producing low cadmium content rice in cadmium contaminated soil, characterized by, It includes the following steps: S1, the multi-dimensional cadmium control ecological regulator according to any one of claims 1-6 is one-time base applied to the bottom of the cadmium contaminated soil; S2, direct seeding of rice seeds in the cadmium contaminated soil to which the multi-dimensional cadmium control ecological regulator is applied, and planting mode is wide and narrow row planting mode, wherein, wide row spacing is 13-26 cm, narrow row spacing is 9 cm, planting density is 20×10 4 -25×10 4 plants / hm 2 .

10. The method of producing low cadmium content rice in cadmium contaminated soil according to claim 9, wherein, Wide row spacing 26 cm, narrow row spacing 9 cm, planting density 20 x 10 4 plants / hm 2 ; Or, wide row spacing 13 cm, narrow row spacing 9 cm, planting density 25 x 10 4 plants / hm 2 .

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