A method to improve the quality of Chinese cabbage and reduce its cadmium absorption.

Abstract

The invention discloses a method for improving the quality of Chinese cabbage and reducing the absorption of cadmium by Chinese cabbage, comprising the following steps: step S1. seed treatment: selecting excellent Chinese cabbage seeds and removing mucus on the surface of the Chinese cabbage seeds; step S2. seed sowing: sowing Chinese cabbage seeds in the soil and irrigating the Chinese cabbage seeds with clean water; step S3. seed cultivation: when the Chinese cabbage grows to three leaves and one heart or four leaves and one heart, spraying water-soluble fertilizers, agents and irrigation water, the agents include salicylic acid, peony bark extract, black soybean extract, chitosan oligosaccharide, harvesting mature Chinese cabbage, and determining the quality of the Chinese cabbage and the cadmium content of the Chinese cabbage. The method is environmentally friendly, does not generate secondary pollution and damage soil structure, can effectively improve the quality of Chinese cabbage, reduce the absorption of cadmium by Chinese cabbage, realize large-scale artificial planting of Chinese cabbage, and promote the development of Chinese cabbage planting industry.

Description

Technical Field

[0001] The invention belongs to the field of agricultural planting, and in particular relates to a method for improving the quality of Chinese cabbage and reducing the absorption of cadmium by the Chinese cabbage. Background Art

[0002] Chinese cabbage, also known as Chinese cabbage, is a biennial herb in the genus Brassica of the family Cruciferae. It is tender, sweet, rich in fiber, vitamins, protein and minerals, and is one of the specialty vegetables in southern my country. However, Chinese cabbage has a strong ability to absorb and accumulate cadmium. Excessive accumulation of cadmium in the human body will have an impact on human health. Therefore, it is of great significance to control the absorption and accumulation of cadmium in the soil by Chinese cabbage and reduce the cadmium content in the stems and leaves of Chinese cabbage.

[0003] At present, the main method to reduce the absorption of cadmium by Chinese cabbage is to add heavy metal passivators to the soil. Heavy metal passivators added to the soil include inorganic fertilizers (nitrate nitrogen fertilizers, ammonium nitrogen fertilizers, etc.), organic fertilizers (straw, chicken manure, bone meal, etc.) and improvers. For example, adding soil improver TM, silicon conditioner, peat, bone meal, zeolite, etc. to the soil can reduce the cadmium content in the stems and leaves of Chinese cabbage. However, adding soil heavy metal passivators to the soil often has the following problems: (1) The amount of heavy metal passivators used is large, the cost is high, and continuous addition is required every year to maintain the effect; (2) The large amount of heavy metal passivators used can easily damage the soil structure and affect plant growth; (3) It can easily cause secondary pollution, pose a safety hazard, and is environmentally unfriendly; (4) The effectiveness is short and is often only effective for one application in one season; (5) Due to the large differences in soil properties, the remediation effect of heavy metal passivators is often not ideal; (6) The life of heavy metal passivators is easily affected by soil properties. For example, in some acid rain areas, the decrease in soil pH will greatly shorten the life of heavy metal passivators.

[0004] Therefore, inventing a method to reduce the cadmium content in the stems and leaves of Chinese cabbage and be friendly to the soil environment is of great significance for the safe production of Chinese cabbage. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, the object of the present invention is to provide a method for improving the quality of Chinese cabbage and reducing its absorption of cadmium. The method is environmentally friendly, will not cause secondary pollution or damage the soil structure, can effectively improve the quality of Chinese cabbage, reduce its absorption of cadmium, realize large-scale artificial cultivation of Chinese cabbage, and promote the development of the Chinese cabbage planting industry.

[0006] A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium comprises the following steps:

[0007] Step S1. Seed treatment: Select high-quality Chinese cabbage seeds and remove mucus from the surface of the Chinese cabbage seeds;

[0008] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil and irrigating the Chinese cabbage seeds with clean water;

[0009] Step S3. Seed cultivation: When the Chinese cabbage grows to three leaves and one heart or four leaves and one heart, spray water-soluble fertilizers, chemicals and irrigation water, wherein the chemicals include salicylic acid, peony bark extract, black soybean extract and chitosan oligosaccharide, harvest mature Chinese cabbage, and measure the quality of the Chinese cabbage and the cadmium content of the Chinese cabbage.

[0010] The present invention can effectively improve the quality of Chinese cabbage by spraying the agent on the Chinese cabbage, and reduce the absorption of cadmium by the Chinese cabbage. The agent is environmentally friendly, will not cause secondary pollution and damage the soil structure, is less affected by the soil properties, will not deteriorate in a short time, and has a slow-release effect, can improve the quality of the Chinese cabbage for a long time, and reduce the absorption of cadmium by the Chinese cabbage.

[0011] Salicylic acid, also known as o-hydroxybenzoic acid, is a simple phenolic compound produced in plants and widely found in higher plants. Salicylic acid has a strong physiological effect on plant disease resistance, drought resistance, salt and alkali resistance and other adversities, and can affect plant growth and development by regulating plant morphology, photosynthetic characteristics, physiological and biochemical aspects. Spraying salicylic acid at an appropriate concentration can increase the content of osmotic regulating substances such as proline and soluble protein, and improve the activity of its antioxidant enzymes, thereby alleviating the damage of temperature stress to plants.

[0012] Peony bark, also known as peony root bark, peony bark, and peony root, is the dried root bark of the peony plant of the genus Paeoniaceae. Peony bark extract mainly contains phenols and phenolic glycosides, triterpenes, monoterpenes and glycoside compounds, sterols and their glycosides, etc.

[0013] Black soybean, also known as black bean, is a soybean with black seeds, rich in protein, fat, carbohydrates, and trace elements such as carotene. Black soybean extract is rich in cyanidin, catechins, oligomeric proanthocyanidins, polyphenols, etc.

[0014] Chitosan oligosaccharides are a type of water-soluble oligosaccharide obtained by degradation of chitosan, a product of chitin deacetylation, and formed by 2-10 amino glucose linked by β-1,4-glycosidic bonds. They are cationic oligosaccharides and alkaline oligosaccharides existing in natural sugars, also known as glucosamine oligosaccharides, and have a sustained release effect. Chitosan oligosaccharides have higher activity than chitosan, have a small molecular weight, are more soluble in water, have weak accumulation effects in organisms, and have no toxic side effects. They also have the biological function of inducing plant stress defense responses, including inhibiting fungal growth, enhancing the activity of multiple defense enzymes, phytoalexin synthesis and accumulation, lignification and other active functions; improving the quality and yield of horticultural products, and preventing and controlling diseases such as pepper blight and tobacco virus disease.

[0015] The inventors unexpectedly discovered in the experiment that the addition of peony bark extract and black soybean extract can effectively enhance the effect of salicylic acid and chitosan oligosaccharide on Chinese cabbage, improve the quality of Chinese cabbage and reduce the absorption of cadmium by Chinese cabbage. The possible reason is that the polar groups on the peony bark extract and the black soybean extract react with the hydroxyl, amino and carboxyl groups on the molecular chains of salicylic acid and chitosan oligosaccharide, thereby enhancing the effect of salicylic acid and chitosan oligosaccharide on Chinese cabbage, effectively improving the quality of Chinese cabbage and reducing the absorption of cadmium by Chinese cabbage.

[0016] Salicylic acid will decompose under light. There are electrostatic effects and hydrogen bonding effects between chitosan oligosaccharides and salicylic acid, peony bark extract and black soybean extract, which make the prepared agent have a good sustained-release effect, making it difficult for salicylic acid to be decomposed and rendered ineffective under light. Reducing the amount of salicylic acid used can improve the quality of Chinese cabbage for a long time and reduce the absorption of cadmium by Chinese cabbage.

[0017] Preferably, in step S1, the high-quality seeds are plump in appearance, bright in color, have a small amount of floating during soaking, and are elastic when squeezed by hand after soaking.

[0018] Preferably, in step S1, the step of removing mucus from the surface of seeds specifically comprises the following steps: soaking the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, scrubbing and washing repeatedly, and rinsing with clean water.

[0019] Preferably, in step S2, the Chinese cabbage seeds are irrigated with clean water 1-2 times a day.

[0020] Preferably, the medicament is prepared from salicylic acid, peony bark extract, black soybean extract, chitosan oligosaccharide and water.

[0021] Preferably, the concentrations of salicylic acid, peony bark extract, black soybean extract and chitosan oligosaccharide in water are 30-80 mg / L salicylic acid, 20-50 mg / L peony bark extract, 30-60 mg / L black soybean extract and 25-50 mg / L chitosan oligosaccharide, respectively.

[0022] More preferably, the concentrations of salicylic acid, peony bark extract, black soybean extract, and chitosan oligosaccharide in water are 50 mg / L salicylic acid, 30 mg / L peony bark extract, 40 mg / L black soybean extract, and 30 mg / L chitosan oligosaccharide, respectively.

[0023] Preferably, in step S3, the method for extracting the Paeonia suffruticosa root extract comprises the following steps:

[0024] The peony bark is crushed, sieved, added with water, refluxed for extraction, filtered while hot, and the filtrate is concentrated to obtain the peony bark extract.

[0025] The peony bark extract obtained by water extraction in this scheme has a better effect on the sustained release effect of the preparation of the drug, the quality of Chinese cabbage, and the effect of reducing the absorption of cadmium by Chinese cabbage. The possible reason is that the interaction between the peony bark extract obtained by extracting peony bark with water and the black soybean extract, salicylic acid and chitosan oligosaccharides is stronger.

[0026] Preferably, in step S3, the method for extracting the black soybean extract comprises the following steps:

[0027] The black soybeans are crushed, sieved, extracted with water, ultrasonically extracted, filtered, and the filtrate is concentrated to obtain the peony bark extract.

[0028] In this scheme, the black soybean extract obtained by water extraction is used to prepare the sustained-release effect of the drug, improve the quality of Chinese cabbage, and reduce the absorption of cadmium by Chinese cabbage. The possible reason is that the interaction between the black soybean extract obtained by extracting black soybean with water and the peony bark extract, salicylic acid and chitosan oligosaccharide is stronger.

[0029] Preferably, in step S3, when the Chinese cabbage grows to have three leaves and one heart or four leaves and one heart, it is irrigated with clean water 1-2 times a day.

[0030] Preferably, in step S3, when the Chinese cabbage grows to three leaves and one heart or four leaves and one heart, water-soluble fertilizer and pesticide are sprayed every 5-8 days, and 5 L / m of water-soluble fertilizer is sprayed each time. 2 , spray 5L / m each time 2 . DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] The water-soluble fertilizer was purchased from Zhengzhou Tianfeng Biochemical Engineering Co., Ltd. and was selected from Aoneng Black Gold 668.

[0033] The soil in the test site is the location of Guangdong Lianshi Ecological Agriculture Development Co., Ltd. The Cd content of the soil is 0.24 mg / kg.

[0034] The vegetable heart of the present invention is selected from sugar beet heart 31, seeds of Guangzhou Vegetable Seed Company, and has a growing period of about 35 days.

[0035] Example 1: Preparation of Paeonia suffruticosa Andrews extract.

[0036] Weigh 100 kg of peony bark and crush it, then pass it through a 100-mesh sieve for later use, add 5-10 times of water to the sieved peony bark fine powder, reflux extract at a temperature of 90-100° C. for 12-24 hours, filter while hot after extraction, and concentrate the filtrate under reduced pressure to obtain the peony bark extract, which is stored away from light.

[0037] Example 2: Preparation of black soybean extract.

[0038] Weigh 100 kg of black soybeans, crush them, and pass them through an 80-mesh sieve for later use. Add 5-10 times of water to the sieved peony bark fine powder, extract at a temperature of 40-50°C for 4-6 hours, and after the extraction is completed, perform ultrasonic extraction for 2-3 hours, filter at room temperature, and concentrate the filtrate under reduced pressure to obtain a black soybean extract.

[0039] Example 3: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0040] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0041] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0042] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid, peony bark extract, black soybean extract, and chitosan oligosaccharide to the following concentrations: salicylic acid 50 mg / L, peony bark extract prepared in Example 1 30 mg / L, black soybean extract prepared in Example 2 40 mg / L, and chitosan oligosaccharide 30 mg / L. When the Chinese cabbage grows to four leaves and one heart, spray water-soluble fertilizers and agents every 5-8 days, and spray 5 L / m of water-soluble fertilizer each time. 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0043] Example 4: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0044] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0045] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0046] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid, peony bark extract, black soybean extract, and chitosan oligosaccharide to the following concentrations: salicylic acid 30 mg / L, peony bark extract 50 mg / L prepared in Example 1, black soybean extract 30 mg / L prepared in Example 2, and chitosan oligosaccharide 50 mg / L. When the Chinese cabbage grows to four leaves and one heart, spray water-soluble fertilizers and agents every 5-8 days, and spray 5 L / m of water-soluble fertilizer each time. 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0047] Example 5: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0048] Step S1. Seed treatment: select seeds with full appearance and bright color, with a small number of floating seeds during soaking, and seeds that are elastic after being squeezed by hand, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0049] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0050] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid, peony bark extract, black soybean extract, and chitosan oligosaccharide to the following concentrations: salicylic acid 80 mg / L, peony bark extract prepared in Example 1 20 mg / L, black soybean extract prepared in Example 2 60 mg / L, and chitosan oligosaccharide 25 mg / L. When the cabbage grows to four leaves and one heart, spray water-soluble fertilizers and agents every 5-8 days, and spray 5 L / m of water-soluble fertilizer each time. 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0051] Comparative Example 1: Preparation of Paeonia suffruticosa Andrews extract.

[0052] Weigh 100 kg of peony bark and crush it, then pass it through a 100-mesh sieve for later use. Add 5-10 times of n-hexane to the sieved peony bark fine powder, reflux extract at 70°C for 12-24 hours, filter while hot after extraction, and concentrate the filtrate under reduced pressure to obtain the peony bark extract, which is stored away from light.

[0053] Comparative Example 2: Preparation of Paeonia suffruticosa Andrews extract.

[0054] Weigh 100 kg of peony bark and crush it, then pass it through a 100-mesh sieve for later use. Add 5-10 times of ethyl acetate to the sieved peony bark fine powder, reflux and extract at 77°C for 12-24 hours. After the extraction is completed, filter it while hot, concentrate the filtrate under reduced pressure to obtain the peony bark extract, and store it in the dark.

[0055] Comparative Example 3: Preparation of Paeonia suffruticosa Andrews extract.

[0056] Weigh 100 kg of peony bark and crush it, then pass it through a 100-mesh sieve for later use. Add 5-10 times of ethanol to the sieved peony bark fine powder, reflux extract at 78° C. for 12-24 hours, filter while hot after extraction, and concentrate the filtrate under reduced pressure to obtain the peony bark extract, which is stored away from light.

[0057] Comparative Example 4: Preparation of black soybean extract.

[0058] Weigh 100 kg of black soybeans, crush them, and pass them through an 80-mesh sieve for later use. Add 5-10 times of ethanol to the sieved peony bark fine powder, extract at a temperature of 40-50°C for 4-6 hours, and after the extraction is completed, perform ultrasonic extraction for 2-3 hours, filter at room temperature, and concentrate the filtrate under reduced pressure to obtain a black soybean extract.

[0059] Comparative Example 5: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0060] The Paeonia suffruticosa Andrews extract prepared in Example 1 in Example 3 was replaced with the Paeonia suffruticosa Andrews extract prepared in Comparative Example 1, and the remaining steps were the same as in Example 3.

[0061] Comparative Example 6: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0062] The Paeonia suffruticosa Andrews extract prepared in Example 1 in Example 3 was replaced with the Paeonia suffruticosa Andrews extract prepared in Comparative Example 2, and the remaining steps were the same as in Example 3.

[0063] Comparative Example 7: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0064] The Paeonia suffruticosa Andrews extract prepared in Example 1 in Example 3 was replaced with the Paeonia suffruticosa Andrews extract prepared in Comparative Example 3, and the remaining steps were the same as in Example 3.

[0065] Comparative Example 8: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0066] The black soybean extract prepared in Example 2 in Example 3 was replaced by the black soybean extract prepared in Comparative Example 4, and the remaining steps were the same as in Example 3.

[0067] Comparative Example 9: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0068] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0069] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0070] Step S3. Seed cultivation: When the cabbage grows to four leaves and one heart, spray water-soluble fertilizer every 5-8 days, and spray 10L / m 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0071] Comparative Example 10: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0072] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0073] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0074] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid and chitosan oligosaccharide to the following concentrations: salicylic acid 50mg / L, chitosan oligosaccharide 30mg / L, when the cabbage grows to four leaves and one heart, spray water-soluble fertilizer and agent every 5-8 days, spray 5L / m of water-soluble fertilizer each time 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0075] Comparative Example 11: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0076] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0077] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0078] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid, black soybean extract, and chitosan oligosaccharide to the following concentrations: salicylic acid 50 mg / L, black soybean extract prepared in Example 2 70 mg / L, and chitosan oligosaccharide 30 mg / L. When the cabbage grows to four leaves and one heart, spray water-soluble fertilizers and agents every 5-8 days, and spray 5 L / m of water-soluble fertilizer each time. 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0079] Comparative Example 12: A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0080] Step S1. Seed treatment: Select seeds with full appearance and bright color, with a small number of floating seeds during soaking and elastic seeds squeezed by hand after soaking, soak the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, repeatedly scrub and rinse with clean water to remove mucus on the surface of the Chinese cabbage seeds;

[0081] Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil, the row spacing of the Chinese cabbage seeds is 15 cm×15 cm, and the Chinese cabbage seeds are irrigated with clean water 1-2 times a day;

[0082] Step S3. Seed cultivation: Prepare the agent, use water to prepare salicylic acid, peony bark extract, and chitosan oligosaccharide to the following concentrations: salicylic acid 50 mg / L, peony bark extract prepared in Example 1 70 mg / L, and chitosan oligosaccharide 30 mg / L. When the cabbage grows to four leaves and one heart, spray water-soluble fertilizers and agents every 5-8 days, and spray 5 L / m of water-soluble fertilizer each time. 2 , spray 5L / m each time 2 , and irrigate with clean water 1-2 times a day. After 35 days, the mature Chinese cabbage was harvested and the quality and cadmium content of the Chinese cabbage were determined.

[0083] Performance Test:

[0084] (1) Determination of chlorophyll content: The acetone-ethanol extraction method was used. The Chinese cabbage was cut into thin threads of about 1 mm and mixed. 0.1 g was accurately weighed and placed in a stoppered test tube. 10 mL of acetone-ethanol extract with a volume ratio of 1:1 was added. The mixture was shaken and covered with a stopper. The Chinese cabbage sample was placed in a dark place until it turned completely white. The green solution was used as the test solution, and the acetone-ethanol extract was used as the blank control. The absorbance A was measured at wavelengths of 663 nm and 645 nm, respectively. 663 , A 645Calculate the chlorophyll content according to the following formula: Chlorophyll content (mg / g) = C × V / W × 10 3 , where C represents the chlorophyll concentration (μg / mL), C = 20.2 × A 645 +8.02×A 663 ; V represents the total volume of the test solution (mL); W represents the weight of the Chinese cabbage heart (g).

[0085] (2) Determination of soluble sugar content: Refer to the concentrated sulfuric acid-anthrone colorimetric method of Li Hesheng (2000). Take 6 test tubes with a scale of 20 mL and add 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mL of 100 μg / mL standard glucose solution respectively, add distilled water to make the solution reach 2.5 mL, and use 2.5 mL of distilled water as a blank control. Add 6.5 mL of anthrone reagent (3 g anthrone + 1.5 L concentrated sulfuric acid, prepared immediately before use) to each of the 6 tubes, shake well, place on a test tube rack, and color at room temperature for 10-15 minutes. Measure the absorbance A at a wavelength of 620 nm. 620 , to measure the absorbance value A 620 The glucose standard curve was drawn with the vertical axis and the glucose content as the horizontal axis, and the regression equation y = 0.0035x + 0.006 was established, R 2 =0.9969.

[0086] Sample treatment: Weigh 0.5g of Chinese cabbage and cut it into pieces, mix it, add it to a conical flask, add 25mL of distilled water, boil it for 20 minutes, filter it into a 100mL volumetric flask after cooling, and dilute it to the scale with distilled water to obtain the soluble sugar extract. Take 1.0mL of soluble sugar extract, add 6.5mL of anthrone reagent and 1.5mL of distilled water, shake and mix it, place it at room temperature for color development for 10-15 minutes, and measure its absorbance at a wavelength of 620nm. Calculate the soluble sugar content of the Chinese cabbage sample according to the following formula: Soluble sugar content (%) = C×V1×100 / V2×W×10 6 , where C is the glucose content obtained from the standard curve (μg); V1 represents the total volume of the soluble sugar extract (mL); V2 represents the volume of the extract during the measurement (mL); and W represents the weight of the Chinese cabbage (g).

[0087] (3) Determination of soluble protein content: Determine by Coomassie Brilliant Blue method. Take 6 test tubes with a scale of 20 mL and add 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mL of 100 μg / mL bovine serum albumin respectively, add distilled water to make the solution reach 1 mL, and use 1 mL of distilled water as a blank control. Add 5 mL of Coomassie Brilliant Blue G-250 solution (100 mg Coomassie Brilliant Blue G-250 + 50 mL 90% ethanol + 100 mL 85% (W / V) phosphoric acid, dilute to 1000 mL) to each of the 6 tubes, shake well, place on a test tube rack, and color at room temperature for 10-15 minutes. Measure the absorbance A at a wavelength of 595 nm. 595 , to measure the absorbance value A 595 The protein standard curve was drawn with y=0.0034x+0.004 as the ordinate and protein content as the abscissa, and the regression equation was established. 2 =0.9983.

[0088] Sample processing: Weigh 0.1g of Chinese cabbage and cut it into pieces, mix it, add 5mL of distilled water and grind it into a homogenate, transfer it to a 10mL centrifuge tube, centrifuge it at 4000r / min for 10min, and collect the supernatant, which is the soluble protein extract. Take 1.0mL of soluble protein extract, add 5mL of Coomassie Brilliant Blue G-250, mix it and let it stand for 10min, and measure its absorbance at a wavelength of 595nm. Calculate the soluble protein content of Chinese cabbage sample according to the following formula: Soluble protein content (mg / g) = C×V1 / V2×W×10 3 , where C is the protein content (μg) obtained from the standard curve; V1 represents the total volume of the soluble protein extract (mL); V2 represents the volume of the extract during the measurement (mL); and W represents the weight of the Chinese cabbage (g).

[0089] (4) Determination of nitrate content: Determine using the test powder method improved by He Duyingqiong. Take 8 25mL test tubes and add 0, 0.5, 1.0, 1.5, 2.0, 2.5, 4.0, 5.0mL of 100μg / mL NaNO3 solution respectively, add distilled water to make the solution reach 25mL, add 0.1g of mixed test powder (citric acid: anhydrous manganese sulfate: anhydrous p-aminobenzenesulfonic acid: naphthylethylenediamine hydrochloride: fine zinc powder = 30:4:1.6:0.8:1) to each of the 8 tubes, shake well, filter after full reaction. Measure the absorbance A at a wavelength of 538nm 538 , to measure the absorbance value A 538 The standard curve was drawn with the concentration of sodium nitrate as the ordinate and the concentration of sodium nitrate as the abscissa, and the regression equation y = 0.0286x + 0.0071 was established. 2 =0.9938.

[0090] Sample treatment: Weigh 5g of Chinese cabbage and cut it into pieces, mix it, add 5mL of distilled water and grind it into a homogenate, transfer it to a 50mL centrifuge tube, stir it thoroughly and filter it into a conical flask, take 5mL of the filtrate, dilute it to 25mL with distilled water, add 0.1g of the mixed test powder, filter it after sufficient reaction, and measure its absorbance value at a wavelength of 538nm. Calculate the nitrate content of the Chinese cabbage sample according to the following formula: Nitrate content (mg / g) = C×V×A / W×10 3 , where C is the nitrate concentration obtained from the standard curve (μg / mL); V is the total volume of the sample solution (mL); A is the dilution factor; and W is the weight of Chinese cabbage (g).

[0091] (5) Determination of Cd content: Rinse the Chinese cabbage repeatedly with distilled water, dry it, grind it into powder, pass it through a 100-mesh sieve, and weigh 0.5-1g of Chinese cabbage powder, add it to a digestion tube, add 10mL concentrated nitric acid + 2mL H2O2, plug it with a perforated tube stopper, treat it overnight, put it in a heavy metal digester, set the digestion temperature to 70-80℃, keep it for 10 minutes, raise the temperature to 100℃, heat and digest until white smoke appears, until the sample solution is colorless and clear, dilute it to 25cm, and wait for testing. Measure it with a flame ion absorption spectrometer. The test results are shown in Table 1.

[0092] Table 1. Test results of Chinese cabbage quality and cadmium absorption by Chinese cabbage.

[0093]

[0094]

[0095] As can be seen from Table 1, the methods of Examples 3-5 of the present invention are beneficial to improving the quality of Chinese cabbage and reducing the absorption of cadmium by Chinese cabbage.

[0096] Compared with Example 3, Comparative Example 9 did not add peony bark extract, black soybean extract, salicylic acid, and chitosan oligosaccharide, and the quality of Chinese cabbage was poor and the Chinese cabbage absorbed more cadmium, indicating that the agent prepared with peony bark extract, black soybean extract, salicylic acid, and chitosan oligosaccharide has a good effect on improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0097] Compared with Example 3, in Comparative Example 10, no peony bark extract and black soybean extract were added. The prepared agent was used for Chinese cabbage, and the quality of the Chinese cabbage decreased and the Chinese cabbage absorbed more cadmium, indicating that the peony bark extract and black soybean extract have a promoting effect on salicylic acid and chitosan oligosaccharides to improve the quality of Chinese cabbage and reduce its absorption of cadmium.

[0098] Compared with Example 3, in Comparative Examples 11 and 12, only peony bark extract or black soybean extract was added. The prepared agents were used for Chinese cabbage, and the quality of the Chinese cabbage decreased and the Chinese cabbage absorbed more cadmium, indicating that peony bark extract and black soybean extract have a synergistic effect in promoting salicylic acid and chitosan oligosaccharides to improve the quality of Chinese cabbage and reduce the absorption of cadmium by the Chinese cabbage.

[0099] Compared with Example 3, Comparative Examples 5-8 added other extraction methods to obtain peony bark extract and black soybean extract. The prepared agents were used for Chinese cabbage, and the quality of the Chinese cabbage decreased and the Chinese cabbage absorbed more cadmium, indicating that the peony bark extract and black soybean extract obtained by other extraction methods had no obvious effect on salicylic acid and chitosan oligosaccharides in improving the quality of Chinese cabbage and reducing its absorption of cadmium.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A method for improving the quality of Chinese cabbage and reducing its absorption of cadmium. It is characterized in that The steps include: Step S1. Seed treatment: Select high-quality Chinese cabbage seeds and remove mucus from the surface of the Chinese cabbage seeds; Step S2. Seed sowing: sowing Chinese cabbage seeds in the soil and irrigating the Chinese cabbage seeds with clean water; Step S3. Seed cultivation: When the Chinese cabbage grows to three leaves and one heart or four leaves and one heart, spray water-soluble fertilizers, chemicals and irrigation water, harvest the mature Chinese cabbage, and measure the quality of the Chinese cabbage and the cadmium content of the Chinese cabbage; The medicament comprises salicylic acid, peony bark extract, black soybean extract and chitosan oligosaccharide; The extraction method of the Paeonia suffruticosa root extract comprises the following steps: Crushing the peony bark, sieving, adding water, refluxing for extraction, filtering while hot, concentrating the filtrate, and obtaining the peony bark extract; The extraction method of the black soybean extract comprises the following steps: Black soybeans are crushed, sieved, extracted with water, ultrasonically extracted, filtered, and the filtrate is concentrated to obtain a peony bark extract; The concentrations of salicylic acid, peony bark extract, black soybean extract and chitosan oligosaccharide in water are respectively 30-80 mg / L salicylic acid, 20-50 mg / L peony bark extract, 30-60 mg / L black soybean extract and 25-50 mg / L chitosan oligosaccharide.

2. The method for improving the quality of Chinese cabbage and reducing its absorption of soil cadmium as claimed in claim 1, It is characterized in that In step S1, the high-quality Chinese cabbage seeds are full in appearance, bright in color, have a small amount of floating seeds during soaking, and are elastic when squeezed by hand after soaking.

3. The method for improving the quality of Chinese cabbage and reducing its absorption of soil cadmium as claimed in claim 1, It is characterized in that In step S1, the method of removing mucus from the surface of Chinese cabbage seeds specifically comprises the following steps: soaking the seeds in a 1% by mass baking soda solution at room temperature for 12-24 hours, scrubbing repeatedly, and rinsing with clean water.

4. The method for improving the quality of Chinese cabbage and reducing its absorption of soil cadmium as claimed in claim 1, It is characterized in that In step S2, the Chinese cabbage seeds are irrigated with clean water 1-2 times a day.

5. The method for improving the quality of Chinese cabbage and reducing its absorption of soil cadmium as claimed in claim 1, It is characterized in that In step S3, when the Chinese cabbage grows to three leaves and one heart or four leaves and one heart, it is irrigated with clean water 1-2 times a day.

6. The method for improving the quality of Chinese cabbage and reducing its absorption of soil cadmium as claimed in claim 1, It is characterized in that In step S3, when the cabbage grows to three leaves and one heart or four leaves and one heart, water-soluble fertilizer and pesticide are sprayed every 5-8 days, and 5L / m of water-soluble fertilizer is sprayed each time. 2 , spray 5L / m each time 2 .

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