Preparation method of CMAKG-SA slow-release water-retaining agent

Abstract

The invention discloses a preparation method of a CMAKG-SA slow-release water-retaining agent, which comprises the following steps: firstly, carrying out carboxymethylation treatment on Sa-son seed gum to obtain carboxymethylated Sa-son seed gum CMAKG, then taking the carboxymethylated Sa-son seed gum as a matrix, taking acrylic acid of which the neutralization degree is adjusted by a potassium hydroxide solution as a reaction monomer, taking N, N-dimethylformamide as a solvent, and carrying out a reaction for 2-3 hours to obtain the CMAKG-SA slow-release water-retaining agent. The preparation method comprises the following steps: taking carboxymethyl artemisia seed gum as a raw material, taking N, N '-methylene bisacrylamide as a cross-linking agent, adding urea as a slow-release nitrogen fertilizer, stirring and mixing, fully swelling the carboxymethyl artemisia seed gum, dropwise adding ammonium persulfate into the mixed solution, generating sodium alginate SA hydrogel through a polymerization reaction, and cross-linking the sodium alginate SA hydrogel with CMAKG to finally prepare the carboxymethyl artemisia seed gum-based composite super absorbent resin. The invention discloses a CMAKG-SA slow-release water-retaining agent. The SA is added into the CMAKG in a cross-linking manner, so that the water retention capacity of aeolian sandy soil, sierozem and gravelly soil can be remarkably improved, the water absorption capacity of the CMAKG-SA reaches 497.32 g / g, after the CMAKG-SA is used, the water potential decreasing trend of leaves is slowed down, and the yield loss under drought stress is reduced.

Description

Technical Field

[0001] This invention relates to the field of water-retaining agent preparation technology, specifically to a method for preparing a CMAKG-SA sustained-release water-retaining agent. Background Technology

[0002] my country safeguards the food security of 1.4 billion people with only 7% of the world's arable land and 6% of its water resources. Water and fertilizer inputs are among the most crucial factors in ensuring food security. Water is a fundamental condition for the growth of all crops; crops cannot grow without water throughout their entire growth cycle. Currently, drought and water scarcity have become constraints on my country's grain output and stable agricultural development, making it essential to improve water resource utilization efficiency. Fertilizer is a vital source of soil nutrients and an irreplaceable part of agricultural production. Studies show that increased fertilizer application significantly promotes crop yields, but fertilizer utilization is often low due to excessive application and ineffective nutrient loss control. In particular, unreasonable irrigation methods and excessive nitrogen fertilizer application lead to nitrogen leaching and eutrophication, threatening food production and environmental security.

[0003] Slow-release fertilizers can effectively improve fertilizer utilization by slowing down nutrient release, while the application of water-retaining agents can retain water in the soil, thus improving irrigation methods and effectively reducing nitrogen infiltration and loss. However, physical adsorption methods have very weak fertilizer loading capacity and a very short release period, and fertilizer solutions containing cations such as potassium chloride, ammonium chloride, calcium chloride, and ammonium sulfate can reduce the water absorption performance of water-retaining agents.

[0004] Therefore, there is an urgent need for a water-retaining agent that combines water retention and fertilizer slow-release functions to improve the utilization rate of water and fertilizer in the soil. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing CMAKG-SA slow-release water-retaining agent. The method uses aqueous solution polymerization to prepare carboxymethyl Artemisia argyi-based composite superabsorbent resin CMAKG-SA. By adding sodium alginate SA and nitrogen fertilizer to carboxymethyl Artemisia argyi CMAKG, its water retention capacity and fertilizer slow-release capacity in sandy soil, gray calcium soil and gravelly soil are improved, so as to improve the water and fertilizer utilization rate of the soil.

[0006] This invention provides a method for preparing a CMAKG-SA sustained-release water-retaining agent, comprising the following steps:

[0007] (1) Preparation of carboxymethylated Artemisia argyi gum: Artemisia argyi gum was added to ethanol, then potassium hydroxide solution was added, and the mixture was stirred evenly at room temperature to obtain Artemisia argyi gum solution A; chloroacetic acid was dissolved in ethanol, then potassium hydroxide solution was added, and the mixture was stirred evenly to obtain chloroacetic acid solution B; half of solution B was slowly added to solution A, the temperature was slowly raised to 55-65℃, and the mixture was stirred for 1-3 hours, then the remaining solution B was added, and the mixture was stirred for 1-3 hours at 55-65℃. After the mixture was filtered, the resulting solid product was washed twice with ethanol solution, dried to constant weight, and ground to obtain carboxymethylated Artemisia argyi gum CMAKG;

[0008] (2) Preparation of water-retaining agent: Under ice bath conditions, the neutralization degree of acrylic acid was adjusted to 70-80% using potassium hydroxide solution to obtain mixture C. After cooling mixture C to room temperature, urea, carboxymethylated Artemisia argyi gum and N,N'-methylenebisacrylamide were added to it in sequence and stirred until completely dissolved to obtain mixture D. Then, mixture D was transferred to a four-necked flask and immersed in a constant temperature water bath at 65-85°C. Under nitrogen protection, the mixture was stirred for 10-20 minutes to allow the carboxymethylated Artemisia argyi gum to fully swell. Then, ammonium persulfate solution was slowly added dropwise using a separatory funnel. After the addition was completed, nitrogen gas was continued to be purged for 10-20 minutes, and the temperature was maintained for 3-5 hours. After the reaction was completed, the product was dried to constant weight and pulverized to obtain the slow-release water-retaining agent CMAKG-SA.

[0009] Preferably, in the Artemisia argyi gum solution A, the ratio of each reagent is Artemisia argyi gum: ethanol: potassium hydroxide solution = (5-7) g: (50-70) ml: (4-6) ml.

[0010] Preferably, in the chloroacetic acid solution B, the ratio of each reagent is chloroacetic acid: ethanol: potassium hydroxide solution = (5-8) g: (20-30) ml: (15-25) ml.

[0011] Preferably, in step (1), the volume concentration of ethanol is 95%, the concentration of potassium hydroxide solution is 25wt%, the reaction temperature is 60℃, and the reaction time is 1h.

[0012] Preferably, in step (2), the proportions of each reagent are as follows: the mass ratio of carboxymethyl arugula to acrylic acid is 5-15%; the molar ratio of urea to acrylic acid is 0.3-0.9 mol / mol; the mass ratio of N,N'-methylenebisacrylamide to acrylic acid is 0.05-0.40 g / g; and the mass ratio of ammonium persulfate to acrylic acid is 0.5-2.5 g / g.

[0013] Preferably, in step (2), the concentration of potassium hydroxide solution is 20 wt%, the concentration of ammonium persulfate solution is 0.1 mol / L, the degree of neutralization is 70%, the reaction temperature is 75°C, and the reaction time is 75 h.

[0014] Preferably, in the Artemisia argyi gum solution A, the ratio of each reagent is Artemisia argyi gum: ethanol: potassium hydroxide solution = 6g: 60ml: 5ml.

[0015] Preferably, in the chloroacetic acid solution B, the ratio of each reagent is chloroacetic acid: ethanol: potassium hydroxide solution = 6.58g: 25ml: 20ml.

[0016] Preferably, in step (2), the proportions of each reagent are as follows: the mass ratio of carboxymethyl arugula to acrylic acid is 15%; the molar ratio of urea to acrylic acid is 0.3 mol / mol; the mass ratio of N,N'-methylenebisacrylamide to acrylic acid is 0.05 g / g; and the mass ratio of ammonium persulfate to acrylic acid is 2.5 g / g.

[0017] Preferably, the four-necked flask is equipped with a mechanical stirrer, a nitrogen line, a separating funnel, and a reflux condenser.

[0018] The beneficial effects of this invention: This invention discloses a method for preparing CMAKG-SA slow-release water-retaining agent. The method first involves carboxymethylating Artemisia argyi gum to obtain carboxymethylated Artemisia argyi gum CMAKG. Then, using carboxymethylated Artemisia argyi gum as the matrix, acrylic acid with a neutralization degree adjusted by potassium hydroxide solution as the reactive monomer, N,N′-methylenebisacrylamide as the crosslinking agent, and urea as a slow-release nitrogen fertilizer, the mixture is stirred and mixed to allow the carboxymethylated Artemisia argyi gum to fully swell. Next, ammonium persulfate is added dropwise to the mixture, and sodium alginate SA hydrogel is generated through polymerization reaction. This hydrogel is then crosslinked with CMAKG to prepare carboxymethylated Artemisia argyi gum-based composite superabsorbent resin, CMAKG-SA slow-release water-retaining agent.

[0019] The cross-linking and addition of SA to CMAKG in this invention significantly improves the water retention capacity of sandy soil, calcareous soil, and gravelly soil, with CMAKG-SA achieving a water absorption capacity of 497.32 g / g. Furthermore, the CMAKG-SA slow-release water-retaining agent prepared in this invention, because it encapsulates urea as a fertilizer within the polymer, only requires some water absorption to tightly retain water and nutrients, slowly releasing them through osmotic pressure difference. This allows plants to simultaneously obtain water and nutrients over a longer period.

[0020] Experiments have verified that 50% DI water stress causes a decrease in leaf water potential before dawn, and the application of CMAKG-SA slows down this downward trend. Furthermore, 50% DI water stress improves the fruit quality of 'Cabernet Sauvignon' grapes and reduces the 100-berry weight, while the application of CMAKG-SA mitigates yield losses under drought stress. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation process of the CMAKG-SA sustained-release water-retaining agent of the present invention;

[0022] Figure 2 The effect of different single factors on the water absorption capacity of CMAKG-SA;

[0023] Figure 3 Fourier transform infrared spectroscopy analysis;

[0024] Figure 4 This is a scanning electron microscope image;

[0025] Figure 5 Swelling kinetics of CMAKG-SA in distilled water;

[0026] Figure 6 The effect of pH on the water absorption capacity of CMAKG-SA;

[0027] Figure 7 The water absorption capacity and relative water absorption ratio of CMAKG-SA in cationic solutions of different concentrations;

[0028] Figure 8 The effect of CMAKG-SA on the water retention capacity of three soil types—aeolian sandy soil, gray calcium soil, and gravelly soil—with the same addition ratio was investigated.

[0029] Figure 9 The effects of different treatments on the fruit quality of 'Cabernet Sauvignon' grapes. Detailed Implementation

[0030] To make the technical solution of the present invention easier to understand, the technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings and specific embodiments.

[0031] I. Implementation Examples

[0032] Example 1:

[0033] The preparation method of the CMAKG-SA sustained-release water-retaining agent in this embodiment includes the following steps:

[0034] (1) Preparation of carboxymethylated Artemisia argyi gum: 6g of Artemisia argyi gum was added to 60ml of 95% ethanol, and then 5ml of 25wt% potassium hydroxide solution was added. The mixture was stirred evenly at room temperature to obtain Artemisia argyi gum solution A; 6.58g of chloroacetic acid was dissolved in 25ml of 95% ethanol, and then 20ml of 25wt% potassium hydroxide solution was added. The mixture was stirred evenly to obtain chloroacetic acid solution B; half of solution B was slowly added to solution A, the temperature was slowly raised to 60℃, and the mixture was stirred for 1h. Then the remaining solution B was added, and the mixture was stirred for 1h at 60℃. After filtration, the resulting solid product was washed twice with ethanol solution, dried to constant weight, and ground to obtain carboxymethylated Artemisia argyi gum CMAKG.

[0035] (2) Preparation of water-retaining agent: Under ice bath conditions, the neutralization degree of 100 mL of acrylic acid was adjusted to 70% using a 20 wt% potassium hydroxide solution to obtain mixture C. After cooling mixture C to room temperature, urea, carboxymethylated arugula gum, and N,N'-methylenebisacrylamide were added to mixture C in sequence according to the following proportions: carboxymethylated arugula gum to acrylic acid mass ratio of 15%, urea to acrylic acid molar ratio of 0.3 mol / mol, and N,N'-methylenebisacrylamide to acrylic acid mass ratio of 0.05 g / g. The mixture was stirred until completely dissolved to obtain mixture D. Then, the mixture D was transferred to a four-necked flask, which was then immersed in a constant temperature water bath at 75°C. Under nitrogen protection, the mixture was stirred for 15 minutes to allow the carboxymethylated Artemisia argyi gum to fully swell. Ammonium persulfate was then weighed according to a mass ratio of ammonium persulfate to acrylic acid of 2.5 g / g and dissolved to obtain a 0.1 mol / L ammonium persulfate solution. The ammonium persulfate solution was slowly added dropwise to the mixture D using a separatory funnel. After the addition was completed, nitrogen gas was continued to be purged for 15 minutes, and the temperature was maintained for 5 hours. After the reaction was completed, the product was dried to constant weight and pulverized to obtain the slow-release water-retaining agent CMAKG-SA.

[0036] Examples 2 to 18:

[0037] The preparation method of the CMAKG-SA sustained-release water-retaining agent in this embodiment differs from that in Example 1 in that the parameters in step (2) are set differently. Specifically, A-the degree of neutralization of acrylic acid (AA) by 20wt% KOH solution (70%, 80%, 90%), B-the amount of carboxymethyl sage gum (CMAKG) added relative to AA (5%, 10%, 15%), C-the molar ratio of urea to AA (0.3mol / mol, 0.6mol / mol, 0.9mol / mol), D-the mass ratio of crosslinking agent MBA to AA (0.05g / g, 0.15g / g, 0.40g / g), E-the mass ratio of initiator APS to AA (0.5g / g, 1.5g / g, 2.5g / g), F-the reaction time (3h, 4h, 5h) and G-the reaction temperature (65℃, 75℃, 85℃) are shown in Table 1.

[0038] II. Water Absorption Performance Test

[0039] The water-retaining agent CMAKG-AKG hydrogel was prepared through Examples 1 to 18. The water absorption properties of the CMAKG-AKG hydrogel were tested and recorded in Table 1.

[0040] Table 1: Comparison of Specific Parameters and Product Performance in Examples 1-18

[0041]

[0042] Figure 2The effects of different single factors on the water absorption capacity of CMAKG-SA were investigated, including: (A) the effect of KOH neutralization degree on the water absorption performance of CMAKG-SA (urea to AA molar ratio of 0.3, reaction time of 5 h, CMAKG addition of 15%, MBA addition of 0.05%, APS addition of 2.5%, and reaction temperature of 75℃); (B) the effect of urea addition amount on the water absorption performance of CMAKG-SA (neutralization degree of 75%, reaction time of 5 h, CMAKG addition of 15%, MBA addition of 0.05%, APS addition of 2.5%, and reaction temperature of 75℃); and (C) the effect of reaction time on the water absorption performance of CMAKG-SA (neutralization degree of 75%, urea to AA molar ratio of 0.3, CMAKG addition of 15%, MBA addition of 0.05%, and APS addition of 2.5%). (D) Effect of carboxymethylated Artemisia annua gum addition on the water absorption properties of CMAKG-SA (neutralization degree 75%, urea to AA molar ratio 0.3, reaction time 5h, MBA addition 0.05%, APS addition 2.5%, reaction temperature 75℃); (E) Effect of crosslinking agent MBA addition on the water absorption properties of CMAKG-SA (neutralization degree 75%, urea to AA molar ratio 0.3, reaction time 5h, CMAKG addition 15%, APS addition 2.5%, reaction temperature 75℃); (F) Effect of initiator APS addition on the water absorption properties of CMAKG-SA (neutralization degree 75%, urea to AA molar ratio 0.3, reaction time 5h, CMAKG addition 15%, MBA addition 0.05%, reaction temperature 75℃).

[0043] Figure 3 Infrared spectra of Artemisia argyi gum, carboxymethyl Artemisia argyi gum, urea, MBA, and superabsorbent polymer (CMAKG-SA). In the AKG spectrum, in the Artemisia argyi gum spectrum, 3428 cm⁻¹... -1 The broad peak at 3442 cm⁻¹ is due to the large number of hydroxyl groups in Artemisia argyi gum; for urea, the peak at 3442 cm⁻¹ is due to the presence of hydroxyl groups in Artemisia argyi gum. -1 and 1658cm -1 The absorption peaks at 3306 cm⁻¹ correspond to the stretching vibrations of -NH and -C=O, respectively; in the MBA spectrum, 3306 cm⁻¹ -1 The stretching vibration of -NH is located at 1656 cm. -1 The point is a stretching vibration of -C=O, 1546cm. -1 The corresponding bending vibration is C–N–H; the spectrum of CMAKG-SA differs from that of the raw material, at 1638 cm⁻¹. -1 The CC=O stretching vibration of CONH2 was observed at 3442 cm. -1 The active hydrogen of -NH2 is significantly weakened at 1149 cm⁻¹. -1The observation of stretching vibrations of CN at the site confirms that CMAKG-SA has successfully undergone graft polymerization.

[0044] Figure 4 Figure A shows untreated CMAKG-SA, and Figure B shows CMAKG-SA soaked in water for 24 hours. A1 and A2 show scanning electron microscope (SEM) images of CMAKG-SA at two different magnifications. It can be seen that the entire surface has many irregular protrusions, exhibiting a network structure, with the fertilizer uniformly dispersed in the hydrogel. After immersing CMAKG-SA in water for 24 hours, the superadsorbent clearly exhibits a three-dimensional polymer network and porous structure. Figure 4 (B1, B2). (Regarding...) Figure 4 A1 was subjected to EDS spectral analysis, and the elements O, C, N, S, and K were mapped as follows: Figure 4 As shown in Figure C, the elements are uniformly distributed, indicating that the product has high stability. The results show that after the reaction, CMAKG-SA forms a hydrogel with a network spatial structure and high stability.

[0045] III. Water Absorption Performance Verification

[0046] 1. Analysis of swelling kinetics of CMAKG-SA in distilled water

[0047] Swelling kinetics is an important characteristic describing water absorption rate. Figure 5 It is evident that swelling equilibrium is essentially reached at 180 min. A good linear relationship exists between t / Qt and t, with a linear correlation coefficient (R² = 0.99993) very close to 1. The results indicate that the pseudo-second-order swelling kinetic model has a good fit for the swelling behavior of CMAKG-SA, and its swelling and water absorption process is mainly controlled by chemisorption.

[0048] 2. Swelling properties of CMAKG-SA in solutions with different pH values

[0049] Figure 6 This graph shows the water absorption performance of superabsorbent polymers in solutions with different pH values. The water absorption performance increases from pH 3 to 7, but decreases with further increases in pH. The polymer exhibits the highest water absorption performance at pH 7.0.

[0050] 3. Effect of cations of different valence states on the water absorption properties of CMAKG-SA

[0051] like Figure 7As shown, for cations of different valence states, low concentrations of salt solutions cause a significant decrease in the relative water absorption ratio of CMAKG-SA. When the concentrations of Na+, K+, and NH4+ solutions increase from 0 to 0.1 wt%, the relative water absorption ratio of CMAKG-SA decreases significantly. When the solute concentration increases from 0.1 wt% to 0.9 wt%, the decrease in the water absorption ratio of CMAKG-SA in each cation solution slows down, with the final decrease in relative water absorption ratio from largest to smallest being for trivalent cations, divalent cations, and monovalent cations.

[0052] 4. Effects of different addition ratios of CMAKG-SA on the water retention capacity of three types of soil

[0053] To verify the water retention capacity of CMAKG-SA in soil, CMAKG-SA was mixed in different proportions into three types of soil: sandy soil, gray-calcareous soil, and gravelly soil. Figure 8 The effects of 8A-CMAKG-SA on the water retention capacity of three soil types; the effect of 8B-CMAKG-SA on the water retention capacity of aeolian sandy soil; the effect of 8C-CMAKG-SA on the water retention capacity of calcareous gray soil; and the effect of 8D-CMAKG-SA on the water retention capacity of gravelly soil were investigated. Figure 8 As shown in Figure A, adding 0.5 wt%, 1 wt%, and 2 wt% CMAKG-SA to soil significantly improved soil water-holding capacity, and the water-holding capacity of the three soil types was directly proportional to the amount of CMAKG-SA added. Adding CMAKG-SA to aeolian sandy soil, calcareous gray soil, and gravelly soil also improved the soil's water retention performance. Figure 8 As shown in B, 8C, and 8D, after 12 days, the relative moisture contents of the sandy soil, calcareous soil, and gravelly soil with added CMAKG-SA were 6.42%–46.99%, 10.55%–46.31%, and 15.90%–39.33%, respectively. At this time, the relative moisture contents of the sandy soil and gravelly soil without added CMAKG-SA were 0%, and the relative moisture content of the calcareous soil was 3.25%.

[0054] IV. Impact on grape growth performance

[0055] 1. Experimental Design and Methods

[0056] Test materials: The experiment was carried out at the experimental site of the water physiology and water-saving cultivation position of the National Modern Grape Industry Technology System in Yuquanying Farm, Ningxia (38°14′25″N, 106°01′43″E). The experimental site is located in the arid area of the mid-temperate zone, with sufficient sunlight, less rainfall, large temperature difference between day and night throughout the year, and the annual effective accumulated temperature can reach 3400 - 3800 °C. In this experiment, 16-year-old 'Cabernet Sauvignon' (Vitis Vinifera L. cv Cabernet Sauvignon) grapes were selected as materials, planted in the east-west direction, with a "factory" shape pruning, plant spacing of 1m × 3m, buried in winter for cold protection, and the irrigation method was drip irrigation. Except for different irrigation amounts, other management indicators were the same. The experiment had three biological replicates, with 10 grapevines in each replicate.

[0057] 2. Experimental design: There were a total of 5 treatment groups in the experiment: 100% DI, normal water supply, and the pre-dawn water potential of the plants was maintained at 0.0 MPa ≥ Ψb ≥ -0.2 Mpa; 50% DI, the irrigation amount was half of 100% DI, water stress; 50% DI + 20 CMAKG - SA, water stress + 20 g / plant CMAKG - SA; 50% DI + 40 CMAKG - SA, water stress + 40 g / plant CMAKG - SA; 50% DI + 80 CMAKG - SA, water stress + 80 g / plant CMAKG - SA.

[0058] All grapevines were treated with normal irrigation from the grape budding stage to the full flowering stage (May 25th), and water stress treatment started on June 25th, 30 days after anthesis (30DAA). CMAKG - SA was applied一次性 according to the experimental design gradient.

[0059] The irrigation method used drip irrigation equipment with a flow rate of 2.0 L·h -1 , and water control valves were installed at both ends of each treatment row. The irrigation time was adjusted in a timely manner according to the rainfall and water evaporation amount to control the irrigation amount.

[0060] 3. Effects of CMAKG - SA application rate on 'Cabernet Sauvignon' grapes

[0061] (1) Effects of CMAKG - SA application rate on the leaf water potential of 'Cabernet Sauvignon' grapes

[0062] It should be noted that the Chinese "一次性" in the original text might be a misspelling. It should probably be "一次性地" or "一次性施加". Here it is translated as "一次性" for the sake of following the original text.During the water stress experiment, the irrigation amount for each treatment group was adjusted, and the degree of water stress was reflected by the pre-dawn leaf water potential measurements. The pre-dawn leaf water potential of vines treated with 100% DI ranged from 0.0 MPa ≥ Ψb ≥ -0.2 MPa, which was within the experimental range. For the 40 DAA-64 DAA treatment, the water potential range for the 50% DI treatment was -0.1 MPa ≥ Ψb ≥ -0.6 MPa, while the leaf water potential of vines treated with CMAKG-SA fell between that of the 100% DI and 50% DI treatments. For the 65 DAA-75 DAA, 92 DAA, 102 DAA, and 118 DAA treatments, the water potential increased due to rainfall.

[0063] (2) Effects of CMAKG-SA application rate on fruit phenotype and quality of 'Cabernet Sauvignon' grapes

[0064] The effects of different treatments on the fruit growth and basic quality indicators of 'Cabernet Sauvignon' grapes, such as Figure 9 As shown. By Figure 9 It can be seen that throughout the entire growth period, as the fruit matures, the soluble solids, 100-fruit weight, and total anthocyanin content of 'Cabernet Sauvignon' fruit show an upward trend, while the titratable acid, total phenol, and tannin content show a downward trend.

[0065] At 121DAA, compared with 100% DI, the 50% DI treatment significantly reduced the 100-fruit weight by 18.34%, significantly increased soluble solids by 8.35%, significantly reduced titratable acid by 26.79%, and significantly increased total phenols, tannins, and anthocyanins by 14.97%, 26.84%, and 35.13%, respectively. Compared with the 50% DI treatment, applying different amounts of CMAKG-SA significantly increased the 100-fruit weight by 2.84%–14.94%, reduced soluble solids by 1.06%–3.63%, and increased titratable acid by 2.13%–11.72%, with significant differences between the 50% DI+40CMAKG-SA and 50% DI+80CMAKG-SA treatments and the 50% DI treatment.

[0066] Compared with the 50% DI treatment, the application of different amounts of CMAKG-SA significantly reduced the total phenolic, tannin, and anthocyanin contents of the fruit by 3.06%–7.68%, 4.16%–10.35%, and 10.89%–19.92%, respectively.

[0067] V. Conclusion

[0068] (1) This invention uses carboxymethylated Artemisia argyi gum (CMAKG-SA), potassium hydroxide (KOH), acrylic acid (AA), ammonium persulfate (APS), and N,N′-methylenebisacrylamide (MBA) as raw materials to prepare CMAKG-SA with a water absorption capacity of 497.32 g / g. The addition of SA can significantly improve the water retention capacity of aeolian sandy soil, calcareous gray soil, and gravelly soil. The water absorption capacity of CMAKG-SA decreases significantly in various cation solutions, and gradually decreases with increasing cation concentration, with the decrease in magnitude from largest to smallest being trivalent cation, divalent cation, and monovalent cation.

[0069] (2) 50% DI water stress caused the leaf water potential to decrease before dawn. The application of CMAKG-SA slowed down the downward trend of leaf water potential. 50% DI water stress improved the fruit quality of 'Cabernet Sauvignon' grapes and reduced the 100-berry weight. The application of CMAKG-SA reduced the yield loss under drought stress. The reduction in the order from greatest to least was 50% DI + 80g CMAKG-SA > 50% DI + 40g CMAKG-SA > 50% DI + 20g CMAKG-SA.

[0070] It should be noted that the embodiments described herein are only some embodiments of the present invention, and not all implementations of the present invention. These embodiments are merely illustrative and are intended only to provide a more intuitive and clear way to understand the content of the present invention, not to limit the technical solutions described herein. All other implementation methods that can be conceived by those skilled in the art without creative effort, as well as other simple substitutions and variations of the technical solutions of the present invention, without departing from the concept of the present invention, are within the protection scope of the present invention.

Claims

1. A method for preparing a CMAKG-SA slow-release water-retaining agent, characterized by, Comprising the following steps: (1) Carboxymethylated artesunate preparation: artesunate is added to ethanol, then potassium hydroxide solution is added, and the mixture is stirred uniformly at room temperature to obtain artesunate solution A; chloroacetic acid is dissolved in ethanol, then potassium hydroxide solution is added, and the mixture is stirred uniformly to obtain chloroacetic acid solution B; half of solution B is slowly added to solution A, the temperature is slowly raised to 55-65°C, and the mixture is stirred for 1-3 h, then the remaining solution B is added, and the mixture is continuously stirred at 55-65°C for 1-3 h; the mixture is filtered, the obtained solid product is washed twice with an ethanol solution, then dried to constant weight and ground to obtain carboxymethylated artesunate CMAKG; (2) Water-retaining agent preparation: under ice bath conditions, the neutralization degree of acrylic acid is adjusted to 70-80% using a potassium hydroxide solution to obtain mixture C; after mixture C is cooled to room temperature, urea, carboxymethylated artesunate and N, N'-methylene bisacrylamide are sequentially added thereto, and the mixture is stirred until all are dissolved to obtain mixture D; mixture D is transferred to a four-necked flask, the four-necked flask is immersed in a constant-temperature water bath at 65-85°C, and the mixture is stirred under nitrogen protection for 10-20 min to allow the carboxymethylated artesunate to fully swell; an ammonium persulfate solution is slowly added dropwise to the mixture using a separatory funnel, nitrogen is continuously passed for 10-20 min after the dropwise addition is completed, and the temperature is maintained for 3-5 h to complete the reaction; the product is dried to constant weight and ground to obtain a slow-release water-retaining agent CMAKG-SA.

2. The preparation method of the CMAKG-SA slow-release water-retaining agent according to claim 1, wherein in the artesunate solution A, the use amount ratio of each reagent is artesunate: ethanol: potassium hydroxide solution = (5-7) g: (50-70) ml: (4-6) ml.

3. The preparation method of the CMAKG-SA slow-release water-retaining agent according to claim 1, wherein in the chloroacetic acid solution B, the use amount ratio of each reagent is chloroacetic acid: ethanol: potassium hydroxide solution = (5-8) g: (20-30) ml: (15-25) ml.

4. The preparation method of the CMAKG-SA slow-release water-retaining agent according to claim 1, wherein in step (1), the volume concentration of ethanol is 95%, the concentration of the potassium hydroxide solution is 25 wt%, the reaction temperature is 60°C, and the reaction time is 1 h.

5. The preparation method of the CMAKG-SA slow-release water-retaining agent according to claim 1, wherein in step (2), the use amount ratio of each reagent is as follows: the mass ratio of carboxymethylated artesunate to acrylic acid is 5-15%; the molar ratio of urea to acrylic acid is 0.3-0.9 mol / mol; the mass ratio of N, N'-methylene bisacrylamide to acrylic acid is 0.05-0.40 g / g; and the mass ratio of ammonium persulfate to acrylic acid is 0.5-2.5 g / g.

6. The preparation method of the CMAKG-SA slow-release water-retaining agent according to claim 1, wherein in step (2), the concentration of the potassium hydroxide solution is 20 wt%, the concentration of the ammonium persulfate solution is 0.1 mol / L; the neutralization degree is 70%, the reaction temperature is 75°C, and the reaction time is 75 h.

7. The method of claim 1, wherein the ratio of each reagent in the solution A of AMG is AMG: ethanol: KOH solution = 6 g: 60 ml: 5 ml.

8. The method of claim 1, wherein the ratio of each reagent in the solution B of chloroacetic acid is chloroacetic acid: ethanol: KOH solution = 6.58 g: 25 ml: 20 ml.

9. The method of claim 1, wherein the ratio of each reagent in the step (2) is as follows: the mass ratio of carboxymethyl AMG to acrylic acid is 15%; the molar ratio of urea to acrylic acid is 0.3 mol / mol; the mass ratio of N, N'-methylenebisacrylamide to acrylic acid is 0.05 g / g; and the mass ratio of ammonium persulfate to acrylic acid is 2.5 g / g.

10. The method of claim 1, wherein the four-necked flask is equipped with a mechanical stirrer, a nitrogen line, a separatory funnel, and a reflux condenser.

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