Cultivation method for improving anthocyanin content and stability in black rice kernels

Abstract

The application discloses a kind of cultivation methods for improving anthocyanin content and stability in black rice kernel, belong to modern agricultural crop cultivation technical field, the cultivation method, comprising the following steps: selecting anthocyanin high-efficiency enrichment type black rice variety;Adopt compound organic seedling substrate and combine seed pretreatment and carry out seedling culture;Specialized foliar fertilizer is sprayed in early heading and flowering and full-bloom stage;The foliar fertilizer is prepared by mixing ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate;Water control and shading treatment are implemented in field management, and chemical herbicide is avoided to use;According to mature state and weather condition, harvest is carried out, and low-temperature segmented drying and light storage are carried out.By the cultivation method of the application, the anthocyanin content (2283-2358 mg / kg) of black rice is significantly improved, and the storage stability (the retention rate is as high as 87.2% for 180 days) is improved, and the nutritional quality and commodity value are effectively considered.

Description

Technical Field

[0001] This invention belongs to the field of modern agricultural crop cultivation technology, and in particular relates to a cultivation method for improving the anthocyanin content and stability in black rice grains. Background Technology

[0002] Black rice is a valuable rice resource, with a nutritional value far exceeding that of ordinary white rice, primarily due to the abundant anthocyanins in its bran layer. Anthocyanins are a class of water-soluble flavonoids with powerful antioxidant activity, anti-inflammatory functions, and various health benefits, including prevention of chronic diseases. In recent years, with the increasing demand for healthy diets, the market value of black rice and its products has become increasingly prominent. However, the instability of anthocyanins in black rice greatly limits its development and utilization. Anthocyanins are easily degraded by factors such as light, temperature, pH, and enzyme activity. Studies have shown that anthocyanins in black rice are relatively stable under pH conditions of 1.0-3.0, and their thermal degradation follows a first-order kinetic equation, with the activation energy decreasing as pH increases (84.05 KJ / mol at pH 1.0, decreasing to 51.52 KJ / mol at pH 4.5). During field growth, post-harvest storage, and processing, anthocyanins are prone to degradation, leading to a decline in the nutritional and economic value of black rice. Current methods for increasing anthocyanin content in black rice mainly focus on post-extraction and stabilization technologies, such as microencapsulation and dry separation to prepare granules. While these methods have some effect, they are costly and may involve the use of organic chemical reagents, making them unsuitable for producing natural health products. In terms of cultivation, although there are reports of increasing anthocyanin content through foliar fertilizers, the effect of a single measure is limited, and a systematic solution is lacking.

[0003] Therefore, there is an urgent need to provide a method that comprehensively improves the anthocyanin content of black rice and prevents its degradation from the cultivation stage, which is of great significance for enhancing the value of the black rice industry. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a cultivation method to improve the anthocyanin content and stability in black rice grains. Specifically, this invention effectively solves the technical challenge of easily degradable anthocyanins in black rice through systematic innovation integrating variety selection, seedling treatment, foliar fertilization, field management, and harvesting and processing.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A cultivation method for improving the anthocyanin content and stability in black rice grains includes the following steps:

[0007] Select black rice varieties that are highly enriched in anthocyanins;

[0008] Seedlings were raised using a composite organic seedling substrate combined with seed pretreatment.

[0009] Foliar fertilizer is sprayed at the early heading and flowering stage and at the full heading stage; the foliar fertilizer is prepared by mixing ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate;

[0010] Implement water regulation and shading measures in field management, and avoid using chemical herbicides;

[0011] Harvest according to maturity and weather conditions, and then perform low-temperature segmented drying and light-proof storage.

[0012] Optionally, the anthocyanin-rich black rice variety is Gannan black rice.

[0013] Furthermore, the raw materials in the composite organic seedling substrate include shiitake mushroom waste, dragon fruit peel, pig manure, coconut shell, vermiculite powder, borax, and garden soil.

[0014] Furthermore, by weight, the composite organic seedling substrate comprises 58 parts of shiitake mushroom waste, 16 parts of vermiculite powder, 36 parts of dragon fruit peel, 45 parts of coconut shell, 36 parts of pig manure, 2.5 parts of borax, and 390 parts of garden soil.

[0015] Optionally, the seed pretreatment step is: soaking in a manganese salt solution followed by drying.

[0016] Optionally, the manganese salt solution is a manganese chloride solution.

[0017] Furthermore, the mass concentration of the manganese salt solution is 0.3%.

[0018] Furthermore, the drying conditions are as follows: drying at 64°C and ultrasonic frequency of 590 MHz until the moisture content is 10%, then steaming at 73°C for 160 seconds, and then removing and cooling for sowing.

[0019] Optionally, the mass ratio of ammonium molybdate, zinc sulfate, and potassium dihydrogen phosphate is (0.8-1.2):(3-5):(100-150).

[0020] Furthermore, the mass ratio of ammonium molybdate, zinc sulfate, and potassium dihydrogen phosphate is 1:4:120.

[0021] Optionally, the foliar fertilizer is applied twice, once at the early heading and flowering stage and once at the full heading stage, with a concentration of 1.5-2.5 g / L each time.

[0022] Optionally, the steps of moisture regulation and shading treatment are as follows:

[0023] Maintain a water depth of 3-5cm in the field during the grain filling period, and drain and dry the field 15-20 days before maturity;

[0024] Provide 30-40% shade during the critical period of anthocyanin accumulation (15-25 days after heading).

[0025] Optionally, the low-temperature segmented drying conditions are as follows: drying is carried out 20 hours after harvesting, first drying at 42℃ to a moisture content of 19%, and then drying at 48℃ to a moisture content of 13.5%.

[0026] This invention utilizes anthocyanin-rich varieties and enhances seedling vigor through a specially formulated seedling substrate (containing shiitake mushroom waste, dragon fruit peel, pig manure, etc.) and manganese chloride seed pretreatment. Foliar fertilizer, a mixture of ammonium molybdate, zinc sulfate, and potassium dihydrogen phosphate, is applied twice during the early heading and flowering stages and at the full heading stage to promote anthocyanin synthesis. Precise water management in the field involves maintaining a shallow water layer during the grain-filling stage, timely field drying before maturity, and providing 30-40% shade during the critical period of anthocyanin accumulation to prevent degradation by strong light. Harvesting is timed to full maturity; in cases of sustained high temperatures, harvesting is delayed until the low-temperature period to ensure coloring, and segmented low-temperature drying and light-protected low-temperature storage are employed within 24 hours. This cultivation method significantly improves the anthocyanin content (2283-2358 mg / kg) and storage stability (87.2% retention rate after 180 days) of black rice, effectively balancing nutritional quality and commercial value.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] 1. Innovative Mechanism and Synergistic Effect: The foliar fertilizer of this invention is not a simple nutrient supplement, but a compound functional agent designed based on the physiological and biochemical mechanisms of anthocyanin synthesis and degradation. The three components complement each other and synergistically enhance each other, achieving an organic unity of "promoting synthesis" and "preventing degradation".

[0029] 2. High anthocyanin content and stability: By applying this invention, the anthocyanin content of black rice can be stabilized at around 2300mg / kg. More importantly, it has excellent storage stability, with a retention rate of over 87% after 180 days at room temperature and away from light, which greatly extends the product's shelf life and efficacy period.

[0030] 3. Environmentally Friendly and High Industrial Value: This invention does not use any harmful chemicals, making the entire process green and safe. Black rice produced using this cultivation method has high added value and strong market competitiveness.

[0031] In summary, this invention discloses a cultivation method that significantly improves the anthocyanin content and stability in black rice grains by integrating agronomic management, particularly innovative foliar nutrition programs, with the goal of synergistically promoting synthesis and preventing degradation. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] This invention provides a systematic method for cultivating black rice, which addresses the problem of easily degraded anthocyanins in black rice through integrated agronomic measures, thereby increasing the content and stability of anthocyanins in black rice, and thus enhancing the nutritional value and market competitiveness of black rice.

[0038] A cultivation method for improving the anthocyanin content and stability in black rice grains includes the following steps:

[0039] (1) Variety selection: Select anthocyanin-rich varieties (such as "Gannan Black Rice") as cultivation objects;

[0040] (2) Seedling treatment: A special seedling substrate is used, which consists of shiitake mushroom waste, vermiculite powder, dragon fruit peel, coconut shell, pig manure, borax and garden soil. This substrate is not only loose and nutritious, but also contains trace elements that promote anthocyanin synthesis. Seed pretreatment uses manganese chloride solution soaking combined with drying treatment at a specific frequency and temperature to effectively improve cell enzyme activity and seed division ability.

[0041] (3) Foliar fertilizer application: Use a special compound fertilizer made of ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate. The mass ratio of ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate is (0.8-1.2):(3-5):(100-150), and the application concentration is 1.5-2.5 g / L. Spray twice at the early heading and flowering stage and at the full heading stage of black rice. This formula can significantly promote anthocyanin biosynthesis and improve the stability of anthocyanins.

[0042] (4) Field management: Implement precise water control strategies, maintain a field water depth of 3-5 cm during the grain filling stage, drain and dry the field 15-20 days before maturity, and provide 30-40% shade during the critical period of anthocyanin accumulation to avoid photodegradation of anthocyanins caused by strong direct sunlight. At the same time, with the goal of "prevention first, comprehensive control", strictly prohibit the use of chemical herbicides to reduce the impact of chemical substances on anthocyanins;

[0043] (5) Harvesting and processing: Harvest when 90% of the rice is mature, the grains are purplish-black and hard (delayed harvesting not only increases the risk of lodging, but may also cause the rice grains to become lighter in color (anthocyanin degradation) or chalky, affecting the appearance quality and nutritional value); after harvesting, carry out segmented low-temperature drying within 24 hours until the moisture content is ≤14% to retain the anthocyanin activity to the maximum extent.

[0044] However, if black rice encounters prolonged high temperatures during its ripening stage, its coloring mechanism will be affected. Therefore, to ensure that black rice is fully colored, if prolonged high temperatures occur in the later stages, harvesting should be delayed until a period of sustained low temperatures occurs. During this period of low temperatures, the black rice will recover its coloring.

[0045] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0046] All raw materials used in this invention were purchased from the market.

[0047] Among them, shiitake mushroom waste, dragon fruit peels, pig manure, coconut shells, vermiculite powder, borax, and garden soil need to be treated. The specific treatment methods are as follows:

[0048] A. First, crush the shiitake mushroom waste and pig manure separately, and place them in a 150℃ environment for continuous steam treatment for 25 minutes; after taking them out, mix them evenly with crushed dragon fruit peel and coconut shell, adjust the moisture content of the material to 65%, and continue to ferment at 50℃ for 70 days to obtain decomposed nutrient material.

[0049] B. Then, thoroughly mix vermiculite powder, borax, garden soil and the above-mentioned decomposed nutrients, control the moisture content to 50%, and place it in an environment of 45℃ to continue fermentation for 5 days, finally making the seedling substrate.

[0050] The technical solution of the present invention will be further illustrated by the following embodiments.

[0051] Example 1: Implementation Case of Demonstration Base

[0052] In 2024, a 30-mu (approximately 2 hectares) experimental demonstration base for "Gannan Black Rice" was established in Chijiang Town, Dayu County, and the cultivation method of this invention was used for large-scale production.

[0053] The specific cultivation process is as follows:

[0054] 1. Variety selection: The "Gannan Black Rice" variety, cultivated by Ganzhou Agricultural Science Research Institute, is selected. This variety has high anthocyanin content, good taste, and stable yield.

[0055] 2. Seedling treatment:

[0056] (1) Seed pretreatment: Black rice seeds were soaked in 0.3% manganese chloride solution for 85 minutes, then dried at 64℃ and 590 MHz until the moisture content was 10%, and then treated with constant temperature steam at 73℃ for 160 seconds. After cooling, the seeds were ready for sowing.

[0057] (2) Preparation of seedling substrate: According to the weight proportions, mix 58 parts of shiitake mushroom waste, 16 parts of vermiculite powder, 36 parts of dragon fruit peel, 45 parts of coconut shell, 36 parts of pig manure, 2.5 parts of borax and 390 parts of garden soil to prepare the substrate. After thorough mixing, disinfect the substrate.

[0058] (3) Sowing: Sow on June 20 at a depth of 2.6cm and use seedling trays.

[0059] 3. Field management:

[0060] (1) Transplanting: Transplant seedlings to the field when they are 25 days old, with a transplanting density of 16.7cm×20cm.

[0061] (2) Water management: Maintain a water depth of 3-5 cm in the field during the grain filling period, and drain and dry the field 18 days before maturity.

[0062] (3) Shade control: During the critical period of anthocyanin accumulation (15-25 days after heading), set up a 40% (shade) shade net to avoid strong direct sunlight.

[0063] 4. Foliar fertilizer application:

[0064] (1) Foliar fertilizer preparation: The mass ratio of ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate is 1:4:120, and the application concentration is 2.0g / L.

[0065] (2) Spraying time and method: Spray for the first time at the early stage of heading and flowering, and spray for the second time at the full heading stage. The amount of spraying each time is 30 kg / mu. Choose a cloudy afternoon to spray evenly until the leaf surface is moist but does not drip.

[0066] 5. Harvesting and processing:

[0067] (1) Harvesting: On October 20 (the mature stage), choose a sunny day to harvest and avoid harvesting on rainy days.

[0068] (2) Drying treatment: Drying begins within 20 hours after harvesting. First, dry at 42℃ to 19% moisture content, and then at 48℃ to 13.5% moisture content.

[0069] (3) Storage: After drying, black rice should be sealed and stored away from light, with the temperature controlled at 15-20℃.

[0070] LC-MS analysis showed that the anthocyanin content of the black rice produced in Example 1 reached 2358 mg / kg. After storage at room temperature and away from light for 180 days, the anthocyanin retention rate reached 87.2%, indicating a significant improvement in anthocyanin stability.

[0071] Example 2

[0072] The only difference from Example 1 is that the ratio of the three raw materials (ammonium molybdate, zinc sulfate, and potassium dihydrogen phosphate) in the foliar fertilizer in step 4 is changed, and five treatments are set up: T1 (corresponding to Example 1 of this invention), T2, T3, T4, and CK (water control), with each treatment repeated three times. The specific ratios are shown in Table 1.

[0073] Table 1. Effects of different foliar fertilizer ratios on the anthocyanin content and stability of black rice.

[0074]

[0075] As can be seen from Table 1, the foliar fertilizer formulations within the specified ratio range (T1, T2, T3) of this invention all exhibit good effects, with the optimal ratio T1 (1:4:120) showing the best anthocyanin content and stability. The imbalanced ratio of T4 significantly reduces the effectiveness, demonstrating the necessity of the specified ratio range for the foliar fertilizer of this invention.

[0076] Comparative Example 1

[0077] A traditional cultivation method for black rice. For details of the cultivation process, please refer to the characteristics and supporting cultivation techniques of the new specialty rice variety Lihei 151 in World Tropical Agriculture Information, Issue 12, 2022.

[0078] Testing revealed that the anthocyanin content of black rice in Comparative Example 1 was 1829 mg / kg; the anthocyanin content of black rice in Example 1 was 28.5% higher than that in Comparative Example 1 (traditional cultivation method). After storage at room temperature and away from light for 180 days, the anthocyanin retention rate was 61.3%.

[0079] Furthermore, compared to Comparative Example 1, the black rice variety was replaced with "Gannan Black Rice," while other cultivation conditions remained the same as in Comparative Example 1. Testing showed that the anthocyanin content of the black rice in Example 1 was 25.5% higher than that of Gannan Black Rice cultivated using traditional methods. After storage at room temperature and away from light for 180 days, the anthocyanin retention rate was 65.3%.

[0080] Comparative Example 2

[0081] The only difference from Example 1 is that the drying conditions in step 5 are changed, and three drying methods are set: D1 (segmented drying as in Example 1 of this invention), D2 (one-time high-temperature drying, 60°C, drying to a moisture content of 13.5%), and D3 (natural sun drying, drying to a moisture content of 13.5%), with each treatment repeated three times. The specific conditions are shown in Table 2.

[0082] Table 2. Effects of different drying methods on the retention rate of anthocyanins in black rice.

[0083]

[0084] As can be seen from Table 2, the segmented low-temperature drying (D1) method used in Example 1 of the present invention has the best effect, with a significantly higher anthocyanin retention rate than other treatments, and still retains 87.2% anthocyanin activity after 180 days.

[0085] Comparative Example 3

[0086] A cultivation method to improve the anthocyanin content and stability in black rice grains: The experimental base is the same as in Example 1.

[0087] The specific cultivation process is as follows:

[0088] 1. Variety selection: The "Gannan Black Rice" variety, cultivated by Ganzhou Agricultural Science Research Institute, is selected. This variety has high anthocyanin content, good taste, and stable yield.

[0089] 2. Seedling treatment:

[0090] (1) Seed pretreatment: Black rice seeds were soaked in 0.3% manganese chloride solution for 85 minutes, then dried at 64℃ and 590 MHz until the moisture content was 10%, and then treated with constant temperature steam at 73℃ for 160 seconds. After cooling, the seeds were ready for sowing.

[0091] (2) Preparation of seedling substrate: According to the weight proportions, mix 58 parts of shiitake mushroom waste, 16 parts of vermiculite powder, 36 parts of dragon fruit peel, 45 parts of coconut shell, 36 parts of pig manure, 2.5 parts of borax and 390 parts of garden soil to prepare the substrate. After thorough mixing, disinfect the substrate.

[0092] (3) Sowing: Sow on June 20 at a depth of 2.6cm and use seedling trays.

[0093] 3. Field management:

[0094] (1) Transplanting: Transplant seedlings to the field when they are 25 days old, with a transplanting density of 16.7cm×20cm.

[0095] (2) Water management: Maintain a water depth of 3-5 cm in the field during the grain filling period, and drain and dry the field 18 days before maturity.

[0096] (3) Shade control: During the critical period of anthocyanin accumulation (15-25 days after heading), set up a 40% (shade) shade net to avoid strong direct sunlight.

[0097] 4. Foliar fertilizer application:

[0098] (1) Foliar fertilizer preparation: The mass ratio of zinc sulfate to potassium dihydrogen phosphate is 4:120, and the application concentration is 2.0g / L.

[0099] (2) Spraying time and method: Spray for the first time at the early stage of heading and flowering, and spray for the second time at the full heading stage. The amount of spraying each time is 30 kg / mu. Choose a cloudy afternoon to spray evenly until the leaf surface is moist but does not drip.

[0100] 5. Harvesting and processing:

[0101] (1) Harvesting: On October 20 (the mature stage), choose a sunny day to harvest and avoid harvesting on rainy days.

[0102] (2) Drying treatment: Drying begins within 20 hours after harvesting. First, dry at 42℃ to 19% moisture content, and then at 48℃ to 13.5% moisture content.

[0103] (3) Storage: After drying, black rice should be sealed and stored away from light, with the temperature controlled at 15-20℃.

[0104] Testing showed that the black rice produced in Comparative Example 3 contained 2010 mg / kg of anthocyanins. After storage at room temperature and away from light for 180 days, the anthocyanin retention rate reached 73.2%.

[0105] Comparative Example 4

[0106] A cultivation method to improve the anthocyanin content and stability in black rice grains: The experimental base is the same as in Example 1.

[0107] 1. Variety selection: The "Gannan Black Rice" variety, cultivated by Ganzhou Agricultural Science Research Institute, is selected. This variety has high anthocyanin content, good taste, and stable yield.

[0108] 2. Seedling treatment:

[0109] (1) Seed pretreatment: Black rice seeds were soaked in 0.3% manganese chloride solution for 85 minutes, then dried at 64℃ and 590 MHz until the moisture content was 10%, and then treated with constant temperature steam at 73℃ for 160 seconds. After cooling, the seeds were ready for sowing.

[0110] (2) Preparation of seedling substrate: According to the weight proportions, mix 58 parts of shiitake mushroom waste, 16 parts of vermiculite powder, 36 parts of dragon fruit peel, 45 parts of coconut shell, 36 parts of pig manure, 2.5 parts of borax and 390 parts of garden soil to prepare the substrate. After thorough mixing, disinfect the substrate.

[0111] (3) Sowing: Sow on June 20 at a depth of 2.6cm and use seedling trays.

[0112] 3. Field management:

[0113] (1) Transplanting: Transplant seedlings to the field when they are 25 days old, with a transplanting density of 16.7cm×20cm.

[0114] (2) Water management: Maintain a water depth of 3-5 cm in the field during the grain filling period, and drain and dry the field 18 days before maturity.

[0115] (3) Shade control: During the critical period of anthocyanin accumulation (15-25 days after heading), set up a 40% (shade) shade net to avoid strong direct sunlight.

[0116] 4. Foliar fertilizer application:

[0117] (1) Foliar fertilizer preparation: The mass ratio of ammonium molybdate to potassium dihydrogen phosphate is 1:120, and the application concentration is 2g / L.

[0118] (2) Spraying time and method: Spray for the first time at the early stage of heading and flowering, and spray for the second time at the full heading stage. The amount of spraying each time is 30 kg per mu. Choose a cloudy afternoon to spray evenly until the leaf surface is moist but does not drip.

[0119] 5. Harvesting and processing:

[0120] (1) Harvesting: On October 20 (the mature stage), choose a sunny day to harvest and avoid harvesting on rainy days.

[0121] (2) Drying treatment: Drying begins within 20 hours after harvesting. First, dry at 42℃ to 19% moisture content, and then at 48℃ to 13.5% moisture content.

[0122] (3) Storage: After drying, black rice should be sealed and stored away from light, with the temperature controlled at 15-20℃.

[0123] Testing showed that the black rice produced in Comparative Example 4 contained 2100 mg / kg of anthocyanins. After storage at room temperature and away from light for 180 days, the anthocyanin retention rate reached 75.4%.

[0124] The above embodiments fully demonstrate the significant effect of the present invention in preventing the degradation of anthocyanins in black rice. Through comprehensive agronomic measures, the content and stability of anthocyanins in black rice are improved simultaneously, which has important value for promotion and application.

[0125] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A cultivation method for improving the anthocyanin content and stability in black rice grains, characterized in that, Includes the following steps: Select a black rice variety that is highly enriched in anthocyanins; the black rice variety that is highly enriched in anthocyanins is Gannan black rice; Seedlings were raised using a composite organic seedling substrate combined with seed pretreatment. Foliar fertilizer is sprayed at the early heading and flowering stage and at the full heading stage; the foliar fertilizer is prepared by mixing ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate; the mass ratio of ammonium molybdate, zinc sulfate and potassium dihydrogen phosphate is 1:4:120; the foliar fertilizer is sprayed twice at the early heading and flowering stage and at the full heading stage, and the concentration of each application is 1.5-2.5 g / L. Water regulation and shading are implemented in field management; Harvest according to maturity and weather conditions, and then perform low-temperature segmented drying and light-proof storage; The conditions for low-temperature segmented drying are as follows: drying is carried out 20 hours after harvesting, first at 42℃ to a moisture content of 19%, and then at 48℃ to a moisture content of 13.5%.

2. The cultivation method for improving the anthocyanin content and stability in black rice grains according to claim 1, characterized in that, The raw materials in the composite organic seedling substrate include shiitake mushroom waste, dragon fruit peel, pig manure, coconut shell, vermiculite powder, borax, and garden soil.

3. The cultivation method for improving the anthocyanin content and stability in black rice grains according to claim 1, characterized in that, The seed pretreatment steps are as follows: soaking in a manganese salt solution followed by drying.

4. The cultivation method for improving the anthocyanin content and stability in black rice grains according to claim 3, characterized in that, The drying conditions are as follows: drying at 64°C and ultrasonic frequency of 590 MHz until the moisture content is 10%, then steaming at 73°C for 160 seconds, and then removing and cooling for sowing.

5. The cultivation method for improving the anthocyanin content and stability in black rice grains according to claim 1, characterized in that, The steps for moisture regulation and shading treatment are as follows: Maintain a water depth of 3-5cm in the field during the grain filling period, and drain and dry the field 15-20 days before maturity; Provide 30-40% shade 15-25 days after heading.

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