CN114711101A - Application of water-retaining agent for vegetable transplantation in vegetable transplantation - Google Patents
Application of water-retaining agent for vegetable transplantation in vegetable transplantation Download PDFInfo
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
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Abstract
The invention discloses an application of a vegetable transplantation water-retaining agent in vegetable transplantation. The application of the water-retaining agent for vegetable transplantation in vegetable transplantation comprises the following steps: the prepared water-retaining agent for vegetable transplantation is directly used for dipping roots in vegetable transplantation, is watered after soil is covered, and is placed in open field. Compared with the prior art, the water-retaining agent for vegetable transplantation has good water absorption and retention, salt and alkali resistance and thermal stability; the use technology of the water-retaining agent for vegetable transplantation is helpful for simplifying the use flow of the water-retaining agent, reducing the time consumption caused by dilution, avoiding the problem of difficult root system taking, and solving the problem of low efficiency in the working process of the prior art to a certain extent.
Description
Technical Field
The invention relates to the technical field of agricultural planting, in particular to an application of a water-retaining agent for vegetable transplantation in vegetable transplantation.
Background
Water is a source of life and plays an important role in agricultural production. With the large-scale development of the vegetable industry in China, the agricultural water accounts for about 70% of the total water consumption in China. In the agricultural production process of vegetables, water retention agents are often used for improving the water utilization rate.
The water-retaining agent can rapidly absorb water which is hundreds times or even thousands times of the weight of the water-retaining agent, form gel after absorbing water, can keep water for a long time, and can repeatedly absorb water and slowly release water for crops to use. In addition, the water-retaining agent also has the effects of preserving heat and fertility, improving the granular structure of soil, increasing the permeability of the soil, influencing the physical and chemical properties of the soil, increasing the water-retaining performance of the soil, improving the utilization efficiency of nutrients and the like. The water-retaining agent is added into soil and seedling raising matrix, so that the fertilizer efficiency can be improved, the seed germination rate can be improved, the growth of crop seedlings and the yield of crops can be increased, and the water-retaining agent has a wide development prospect in agricultural development.
Patent No. CN103740375A discloses a humic acid-based water-retaining agent for vegetables and a preparation method thereof. The water-retaining agent is used for vegetable crops, can improve the utilization rate of water, ensure that the soil fertility is not lost, stimulate the growth and development of vegetables, improve the nutritional function of the vegetables, increase the stress resistance of the crops and increase the yield. A humic acid-based water-retaining agent for vegetables is composed of the following raw materials in parts by weight: 1-5 parts of weathered coal, 40-70 parts of 0.1mol/L sodium hydroxide solution, 2-8 parts of sodium hydroxide with the purity of 98%, 0.5-4 parts of potassium hydroxide with the purity of 98%, 5-20 parts of acrylic acid, 2-8 parts of acrylamide, 0.01-0.05 part of N, N' -methylene-bis-acrylamide, 0.4-2 parts of potassium persulfate and 0.5-5 parts of self-initiation heating agent, and is prepared by adopting a specific method. However, the water-retaining agent is alkaline, has great damage to plant roots and has poor water-retaining effect.
Chinese patent No. CN110476776A discloses the application of a pomace-based water-retaining agent in plug seedling of leaf vegetables. The fruit residue-based water-retaining agent and a seedling substrate are fully and uniformly mixed according to the proportion of 1: 1000-1: 20 and then are used as the seedling substrate containing the fruit residue-based water-retaining agent for hole-tray seeding. The pomace-based water-retaining agent is used for vegetable breeding, can improve soil porosity, maintain soil moisture and fertilizer efficiency, has a slow release effect, can solve the problems of low emergence rate, seedling hardening and the like caused by untimely water supplement in the emergence period and seedling growth period of leaf vegetables, improves the emergence rate and seedling quality, prolongs the watering period and saves water consumption. The water-retaining agent is prepared by using fruit residues as main raw materials, has good biodegradability and no pollution residue, and avoids secondary pollution in the field. However, the pomace has a complex use process and insufficient water retention.
In the prior art, when bare roots of vegetables are transplanted, the roots of the vegetables are evenly dipped with pasty liquid prepared by a water-retaining agent. The method can further improve the survival rate of the planted seedlings, but the water retaining agent has long dilution process in use, complex process and large workload, and diluted particles are sticky to cause small attachment of root systems, thereby causing the problem of lower working efficiency. Improving the effective utilization of water resources is a problem to be solved urgently in agriculture.
Disclosure of Invention
In view of the defects of complex preparation and use process, damage to root systems and poor water retention rate of the vegetable water retention agent in the prior art. In order to solve the defects, the invention aims to provide a preparation method and application of a water retention agent in the vegetable transplanting process, and the water retention agent has good water absorption and retention, saline-alkali resistance and thermal stability; but also helps to simplify the use flow of the water-retaining agent, reduce the time consumption caused by dilution, avoid the problem that the root system is difficult to be dipped, and solve the problem of low efficiency in the working process of the prior art to a certain extent.
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation comprises the following steps:
the water-retaining agent for transplanting vegetables is adopted to dip roots of the vegetables to be tested, then the vegetables are placed in planting furrows dug in open field, watering is carried out immediately after soil covering, and the roots of the vegetables are wrapped by plastic films.
Preferably, the vegetable to be tested is lettuce.
Preferably, the root dipping method is to dip the root in a diluent 100 times of the water-retaining agent for vegetable transplantation or dip the root in the water-retaining agent for vegetable transplantation directly.
In order to reduce pollution and improve environment, the chitosan is selected as a base compound of the water retention agent. Chitosan is the second most abundant natural polymer next to cellulose. It has reactive amino and hydroxyl groups and can be chemically modified under mild reaction conditions. Because of the excellent biocompatibility, biodegradability, repeatability, low toxicity and other properties, the chitosan is selected as an ideal framework for synthesizing the super absorbent polymer. The synthesis method is to graft maleic acid on chitosan. In the reaction of chitosan grafting maleic acid, amino is the main grafting site and crosslinking site. From this, it is inferred that increasing the number of amino groups on the chitosan backbone can improve the salt resistance and pH resistance of the chitosan-based polymer. In addition, the amino group is a hydrophilic group to which more functional groups can be grafted. Under the action of alkali, amino and hydroxyl on chitosan and 2-chloroethyl amine hydrochloride undergo nucleophilic substitution reaction. The 2-amino and 6-hydroxyl of chitosan are the most important positions for nucleophilic substitution, while the 3-hydroxyl has a lower degree of substitution due to steric hindrance, thereby forming 2, 6-diaminoethyl chitosan.
The amino ethyl chitosan is synthesized by taking the amino ethyl chitosan as a framework and graft copolymerization through maleic acid. Initiator and cross-linker are added. First, the initiator decomposes under heating to generate sulfate anionic radicals. The free radicals abstract hydrogen from amino and hydroxyl groups, producing more reactive radicals. The maleic acid molecules approach these reactive sites and become free radical acceptors, resulting in the growth of polymer chains. Meanwhile, the polymer chain can react with a cross-linking agent to generate chemical cross-linking, and finally a network structure is formed. It is contemplated that the carboxyl groups of maleic acid may react with the amino and hydroxyl groups on the chitosan derivative. This interpenetration may be further carried out. The polymer synthesized by the grafting reaction can form an interpenetrating network structure.
Preferably, the preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
s1, adding chitosan powder into the 2-chloroethylamine hydrochloride aqueous solution, stirring in a water bath, and completely dissolving to obtain a chitosan derivative;
s2, adding the chitosan derivative prepared in the step S1 into NaOH aqueous solution, carrying out water bath reaction, and then carrying out freeze drying to obtain 2, 6-diamino ethyl chitosan;
s3, placing the 2, 6-diaminoethyl chitosan prepared in the step S2 into a reactor, adding water, stirring for dissolving, placing the reactor into a water bath, adding an initiator, stirring, adding maleic acid, adding a cross-linking agent aqueous solution into a reaction mixture, continuously stirring under argon, cooling to room temperature, adding a NaOH aqueous solution for regulating the pH value, stirring to generate a gel product, adding methanol into the gel product, completely dehydrating, grinding and sieving the gel particle hardened product to obtain the vegetable transplanting water-retaining agent.
Further preferably, the preparation method of the water-retaining agent for vegetable transplantation comprises the following steps of:
s1, adding 10-20 parts of 150g chitosan powder into 500-800 parts of 0.5-2.0 mol/L2-chloroethylamine hydrochloride aqueous solution, and stirring in a water bath at 60-70 ℃ until the chitosan powder is completely dissolved to obtain a chitosan derivative;
s2, adding 500-800 parts of 0.5-1.5 mol/L NaOH aqueous solution into the chitosan derivative prepared in the step S1, reacting in a water bath at 80-90 ℃ for 15-20 h, and then freeze-drying to obtain 2, 6-diamino ethyl chitosan;
s3, placing the 2, 6-diaminoethyl chitosan prepared in the step S2 into a reactor, adding 400-600 parts of water, stirring and dissolving, placing the reactor into a water bath at 50-70 ℃, adding an initiator with the mass of the solution accounting for 1.0-2.0%, stirring for 20-40 min at 50-70 ℃, adding 50-70 parts of maleic acid, adding 1-3 parts of 0.05-0.2 mol/L cross-linking agent aqueous solution into the reaction mixture, continuously stirring for 2-4 h under argon, cooling the reaction product to room temperature, adding 0.5-1.5 mol/L NaOH aqueous solution to enable the pH value to be 6.5-7.5, generating a gel product after stirring, adding 1500-2500 parts of methanol into the gel product, completely dehydrating for 10-30 h, grinding and sieving the hardened gel particle product to obtain the transplanted vegetable.
Preferably, the lyophilization parameters in step S2 are as follows: pre-freezing for 3-5 h at-32 to-38 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 2-5 Pa, a primary sublimation method is adopted to gradually heat the product, the freeze-drying box plate layer is respectively kept for 2-3 hours at 0 ℃, 5 ℃, 10 ℃ and 15 ℃ to make the ice crystals of the product disappear, and then the temperature is raised to 26-30 ℃ of the drying chamber and kept for 2-3 hours.
Preferably, in step S3, the initiator is one of azobisisobutyronitrile, di-tert-butyl peroxide and ammonium persulfate.
Preferably, in step S3, the cross-linking agent is one of dicumyl peroxide, N-benzyl- (9Z,12Z,15Z) -octadecatriene amide, and hydroxyethyl maleate.
Preferably, the aperture of the sieve used for sieving in the step S3 is 200-400 meshes.
The surface appearance of the chitosan is not smooth, the chitosan derivative becomes smooth after being treated by 2-chloroethyl amine hydrochloride, the number of holes is small, an extra grafting site is provided by adding amino, maleic acid is grafted to 2, 6-diaminoethyl chitosan, the crosslinking process is more uniform, the generated pore structure is more uniform, the formed vegetable transplanting water-retaining agent has a more advanced structure and smaller pore diameter, the pore structure provides a larger specific surface area which can be contacted with water, the water absorption rate can be improved, and the mechanical strength is improved.
Grafted carboxyl is the main water-absorbing group, and grafting of maleic acid can increase the water-absorbing capacity of the modified maleic acid. In addition, the carboxyl group of maleic acid increases osmotic pressure, which also increases the water absorption capacity after maleic acid grafting. However, when the initiator content exceeds 2.0%, the water absorption is lowered due to the generation of radicals by an excessive amount of the initiator, resulting in a shortened average kinetic chain length. Also, an excessive amount of the crosslinking agent may generate a more dense network structure, resulting in a reduction in water absorption. When the content of the crosslinking agent is less than 1.0%, the super absorbent polymer is very soft and cannot maintain a fixed shape. The change in the swelling capacity of the superabsorbent polymer in the buffer solution is due to NH3+And COO-Caused by the interaction of (a). At pH values less than 2, most basic and acidic groups are in non-ionized form, and hydrogen bonding between amine and carboxylic acid (possibly carboxamide) groups may lead to cross-linking and a decrease in swelling capacity. At pH values above 11, the carboxylic acid groups are ionized and the electrostatic repulsion between the charge sites leads to increased swelling, subject to counterions such as Cl-、Na+The influence of (2) can lead to water absorptionDecrease and even cause the superabsorbent polymer to lose its effect. Taking into account NH3+Influence on Water absorption by introducing NH into 2, 6-Diaminoethyl Chitosan3+The water absorption of the polymer in the buffer solution is improved, so that the super absorbent polymer is better adapted to soil conditions. The water retention is determined by the hydrogen bonding and van der waals interactions between water molecules and superabsorbent. The vegetable transplanting water-retaining agent has a more compact network structure, and a stronger network structure has higher water-retaining property. Meanwhile, the higher water absorption capacity can also improve the water retention.
Due to the adoption of the technical scheme, compared with the prior art, the application of the water-retaining agent for vegetable transplantation in vegetable transplantation has the advantages that: 1) the application of the water-retaining agent for vegetable transplantation in vegetable transplantation is provided, the waiting time for the water-retaining agent to be difficult to dilute is reduced, and the waste phenomenon of residual water-retaining agent in a storage box when the water-retaining agent drops downwards after dilution is reduced. 2) The agricultural water-saving device is simple and reliable to use, can be directly operated in the agricultural production process, greatly improves the working efficiency, reduces the labor cost, saves water resources, has strong practicability, and is suitable for popularization. 3) The prepared vegetable transplanting water-retaining agent has the performances of water absorption and retention, salt and alkali resistance and thermal stability.
Drawings
FIG. 1 is a diagram showing the adsorption condition of the water-retaining agent on roots after the water-retaining agent is directly dipped in roots in the vegetable transplantation of example 1.
FIG. 2 is a diagram showing the adsorption condition of the water-retaining agent on roots after the water-retaining agent is dipped in a diluent 100 times the amount of the water-retaining agent for vegetable transplantation in example 5.
FIG. 3 is a comparison graph of the root adsorption conditions after the water-retaining agent for vegetable transplantation is directly dipped in the root and after the water-retaining agent for vegetable transplantation is diluted by 100 times.
Detailed Description
Example 1
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation comprises the following steps:
the root of 15 lettuce is directly dipped by 0.6kg of vegetable transplanting water-retaining agent, then the lettuce is put into a prepared hole tray, watering is carried out immediately after soil covering, the hole tray is put into the open field, and the root of the hole tray is wrapped by a plastic film.
The preparation method of the vegetable transplanting water-retaining agent comprises the following steps:
s1, adding 150g of chitosan powder into 7.5kg of 1 mol/L2-chloroethylamine hydrochloride aqueous solution, and stirring in a water bath at 65 ℃ until the chitosan powder is completely dissolved to prepare the chitosan derivative;
s2, adding 7.5kg of 1mol/L NaOH aqueous solution into the chitosan derivative prepared in the step S1, reacting for 18h in a water bath at 85 ℃, cooling to room temperature, pre-freezing for 4h at-35 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 3Pa, a one-time sublimation method is adopted to gradually heat the product, the temperature of a freeze-drying box plate layer is respectively kept for 2h at 0 ℃, 5 ℃, 10 ℃ and 15 ℃, and then the temperature is raised to 28 ℃ in a drying chamber and kept for 2h to obtain 2, 6-diaminoethyl chitosan;
s3, placing the 2, 6-diaminoethyl chitosan prepared in the step S2 into a reactor provided with a mechanical stirrer and a gas inlet, then 5kg of water is added, stirred and dissolved, the reactor is placed in a water bath at 60 ℃, azobisisobutyronitrile with the mass ratio of 1.5 percent of the solution is added, stirring at 60 deg.C for 30min, adding 600g maleic acid, adding 15g 0.15mol/L N-benzyl- (9Z,12Z,15Z) -octadecatrienal diamide aqueous solution into the reaction mixture, continuously stirring for 3h under argon to cool the reaction product to room temperature, adding 1mol/L NaOH solution to adjust the pH value to 7, stirring to generate gel product, adding 20kg methanol into the gel product, completely dehydrating for 24h, and grinding the hardened product of the gel particles, and sieving by using a 300-mesh sieve to obtain the vegetable transplanting water-retaining agent.
Example 2
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation is basically the same as that in example 1, and the only difference is that: the preparation method of the water-retaining agent for vegetable transplantation is inconsistent.
The preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
s1, adding 7.5kg of 1 mol/L2-chloroethylamine hydrochloride aqueous solution into 7.5kg of 1mol/L NaOH aqueous solution, reacting in a water bath at 85 ℃ for 18h, cooling to room temperature, pre-freezing for 4h at-35 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 3Pa, a one-time sublimation method is adopted to gradually heat the product, the freeze-drying box plate layer is respectively kept at 0 ℃, 5 ℃, 10 ℃ and 15 ℃ for 2h, and then the temperature is raised to 28 ℃ in a drying chamber and kept for 2h to obtain a dried compound;
s3, placing the dried compound prepared in the step S1 in a reactor equipped with a mechanical stirrer and a gas inlet, then 5kg of water is added, stirred and dissolved, the reactor is placed in a water bath at 60 ℃, azobisisobutyronitrile with the solution mass ratio of 1.5 percent is added, stirring at 60 deg.C for 30min, adding 600g maleic acid, adding 15g 0.15mol/L N-benzyl- (9Z,12Z,15Z) -octadecatrienal diamide aqueous solution into the reaction mixture, continuously stirring for 3h under argon to cool the reaction product to room temperature, adding 1mol/L NaOH solution to adjust the pH value to 7, stirring to generate gel product, adding 20kg methanol into the gel product, completely dehydrating for 24h, and grinding the hardened product of the gel particles, and sieving by using a 300-mesh sieve to obtain the vegetable transplanting water-retaining agent.
Example 3
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation is basically the same as that in example 1, and the only difference is that: the preparation method of the water-retaining agent for vegetable transplantation is inconsistent.
The preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
s1, adding 150g of chitosan powder into 7.5kg of 1mol/L NaOH aqueous solution, reacting in a water bath at 85 ℃ for 18h, cooling to room temperature, pre-freezing for 4h at-35 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 3Pa, a one-time sublimation method is adopted to gradually heat the product, the freeze-drying box plate layer is respectively kept at 0 ℃, 5 ℃, 10 ℃ and 15 ℃ for 2h, and then the temperature is raised to 28 ℃ in a drying chamber and kept for 2h to obtain a chitosan compound;
s2, placing the chitosan compound prepared in the step S1 in a reactor equipped with a mechanical stirrer and a gas inlet, then 5kg of water is added, stirred and dissolved, the reactor is placed in a water bath at 60 ℃, azobisisobutyronitrile with the mass ratio of 1.5 percent of the solution is added, stirring at 60 deg.C for 30min, adding 600g maleic acid, adding 15g 0.15mol/L N-benzyl- (9Z,12Z,15Z) -octadecatrienal diamide aqueous solution into the reaction mixture, continuously stirring for 3h under argon to cool the reaction product to room temperature, adding 1mol/L NaOH solution to adjust the pH value to 7, stirring to generate gel product, adding 20kg methanol into the gel product, completely dehydrating for 24h, and grinding the hardened product of the gel particles, and sieving by using a 300-mesh sieve to obtain the vegetable transplanting water-retaining agent.
Example 4
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation is basically the same as that in example 1, and the only difference is that: the preparation method of the water-retaining agent for vegetable transplantation is inconsistent.
The preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
s1, adding 150g of chitosan powder into 7.5kg of 1 mol/L2-chloroethylamine hydrochloride aqueous solution, and stirring in a water bath at 65 ℃ until the chitosan powder is completely dissolved to prepare the chitosan derivative;
s2, adding 7.5kg of 1mol/L NaOH aqueous solution into the chitosan derivative prepared in the step S1, reacting in a water bath at 85 ℃ for 18h, cooling to room temperature, pre-freezing for 4h at-35 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 3Pa, a one-time sublimation method is adopted to gradually heat the product, the freeze-drying box plate layer is respectively kept at 0 ℃, 5 ℃, 10 ℃ and 15 ℃ for 2h, and then the temperature is raised to 28 ℃ in a drying chamber and kept for 2h to obtain 2, 6-diamino ethyl chitosan;
s3, placing the 2, 6-diaminoethyl chitosan prepared in the step S2 into a reactor provided with a mechanical stirrer and a gas inlet, then 5kg of water is added, stirred and dissolved, the reactor is placed in a water bath at 60 ℃, azobisisobutyronitrile with the mass ratio of 1.5 percent of the solution is added, stirring at 60 deg.C for 30min, adding 15g 0.15mol/L N-benzyl- (9Z,12Z,15Z) -octadecatrienal amide aqueous solution into the reaction mixture, continuously stirring for 3h under argon to cool the reaction product to room temperature, adding 1mol/L NaOH solution to adjust the pH value to 7, stirring to generate gel product, adding 20kg methanol into the gel product, completely dehydrating for 24h, and grinding the hardened product of the gel particles, and sieving by adopting a 300-mesh sieve to obtain the vegetable transplanting water-retaining agent.
Example 5
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation comprises the following steps:
adding 0.6kg of vegetable transplanting water-retaining agent into 60kg of water, stirring uniformly, soaking the roots of 15 lettuce plants in the water-retaining agent solution for 1min, placing the lettuce plants into a prepared hole tray, immediately watering after covering soil, and completely watering, wherein the hole tray is placed in the open field, and the roots of the hole tray are wrapped by a plastic film.
The preparation method of the water-retaining agent for vegetable transplantation is the same as that in example 1, and the details are not repeated here.
Comparative example 1
The application of the water-retaining agent for vegetable transplantation in vegetable transplantation is basically the same as that in example 1, and the only difference is that: the preparation method of the water-retaining agent for vegetable transplantation is inconsistent.
The preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
placing 5kg of water in a reactor provided with a mechanical stirrer and a gas inlet, placing the reactor in a water bath at 60 ℃, adding azobisisobutyronitrile with the mass ratio of 1.5 percent of the solution, stirring for 30min at 60 ℃, adding 15g of 0.15mol/L N-benzyl- (9Z,12Z,15Z) -octadecenylamide aqueous solution into the reaction mixture, continuously stirring for 3h under argon gas to cool the reaction product to room temperature, adding 1mol/L NaOH solution to make the pH value of the reaction product be 7, stirring to generate a gel product, adding 20kg of methanol into the gel product, completely dehydrating for 24h, grinding the hardened product of the gel particles, and sieving by using a 300-mesh sieve to obtain the vegetable transplanting water-retaining agent.
Test example 1
Soil moisture determination
After planting, soil humidity of examples and comparative examples was tested at intervals of 2, 4, 1, 6, 10 days, respectively, wherein raining was performed on the 1 st day of planting, raining was performed on the 5 th day of planting, raining was performed on the 12 th day of planting, raining was performed on the 23 th day of planting, and other times were cloudy or cloudy, and an average value was taken by testing each sample three times at each time point. The test results are shown in Table 1.
Table 1: soil moisture test results
| Experimental protocol | At an interval of 2 days | At intervals of 4 days | At intervals of 1 day | At intervals of 6 days | At intervals of 10 days |
| Example 1 | 21.8％ | 15.9％ | 13.1％ | 18.3％ | 19.5％ |
| Example 2 | 17.2％ | 13.2％ | 11.6％ | 16.1％ | 17.0％ |
| Example 3 | 17.7％ | 13.7％ | 12.2％ | 17.0％ | 17.8％ |
| Example 4 | 17.3％ | 13.4％ | 11.7％ | 16.2％ | 17.3％ |
| Example 5 | 21.9％ | 19.05％ | 12.4％ | 18.15％ | 19.35％ |
| Comparative example 1 | 16.1％ | 12.0％ | 10.3％ | 15.3％ | 15.9％ |
It can be seen from table 1 that the later soil humidity of embodiment 1 is the highest, and the main reason probably lies in the use technique of vegetable transplanting water retaining agent among embodiment 1 on the one hand and adopts the vegetable transplanting water retaining agent directly to dip in the root to lettuce, and the vegetable transplanting water retaining agent has not absorbed water completely after dipping in the root, and is more abundant to the absorption of later stage rainwater, and the water retention effect is longer moreover, and it is higher to look for a long time, and the mode of directly dipping in the root of using is handled soil later stage humidity. On the other hand, the surface appearance of the chitosan is not smooth, the chitosan has reactive amino and hydroxyl, and the chitosan derivative becomes smooth and has fewer holes after being treated by 2-chloroethylamine hydrochloride. Amino and ethyl are formed on the chitosan, the addition of the amino provides an additional grafting site, and maleic acid is grafted onto the 2, 6-diaminoethyl chitosan, so that the crosslinking process is more uniform, and the super absorbent polymer successfully prepared has a large amount of pores with uniform size. The polymer synthesized by the grafting reaction can form an interpenetrating network structure, the developed pore structure can accelerate the diffusion of water in the network structure, the formed vegetable transplanting water-retaining agent has a more advanced structure and smaller pore diameter, the pore structure provides larger specific surface area which can be contacted with water, the water absorption capacity and the water absorption speed are improved, and the mechanical strength is also improved.
Test example 2
Water absorption multiple test of water-retaining agent
Weighing 0.10g of water retention agent, respectively adding 100ml of distilled water, tap water and underground water, standing for 60min to enable the water retention agent to reach water absorption saturation, measuring the water absorption multiple, testing each sample for three times, and taking an average value.
Table 2: water absorption multiple test result of water-retaining agent
| Experimental protocol | Distilled water | Tap water | Ground water |
| Example 1 | 631.23 | 401.62 | 295.26 |
| Example 2 | 336.03 | 267.31 | 178.12 |
| Example 3 | 378.12 | 292.29 | 216.28 |
| Example 4 | 403.20 | 303.49 | 231.10 |
| Example 5 | 630.81 | 397.30 | 293.91 |
| Comparative example 1 | 47.09 | 36.09 | 33.49 |
It can be seen from table 2 that the water absorption capacity of the water retention agent is higher in example 1 and example 5, and different water qualities have different water absorption capacities, probably because the water absorption capacity of the water retention agent is affected by ions in water. The water absorption multiple of the water-retaining agent is reduced in groundwater compared with tap water, mainly because the water-retaining agent has high K, Ca, Na, Al and other ions in groundwater and is combined with hydrophilic sites of the water-retaining agent, so that the water absorption multiple of the water-retaining agent is reduced.
Examples 1 and 5 have the best water absorption effect, probably because chitosan is an ideal backbone for the synthesis of superabsorbent polymers. Mixing chitosan and 2-chloroethyl amine hydrochloride, and carrying out nucleophilic substitution reaction on amino and hydroxyl on the chitosan and the 2-chloroethyl amine hydrochloride under the action of alkali. The 2-amino and 6-hydroxyl of chitosan are the most important positions for nucleophilic substitution, while the 3-hydroxyl has a lower degree of substitution due to steric hindrance, thereby forming 2, 6-diaminoethyl chitosan. The introduction of the aminoethyl group breaks up the hydrogen bonds within and between the chitosan molecules. 2, 6-diamino ethyl chitosan is taken as a framework, and the amino ethyl chitosan is synthesized by maleic acid graft copolymerization. Initiator and cross-linker are added. First, the initiator decomposes under heating to generate sulfate anionic radicals. The free radicals abstract hydrogen from amino and hydroxyl groups, producing more reactive radicals. The maleic acid molecules approach these reactive sites and become free radical acceptors, resulting in the growth of polymer chains. Meanwhile, the polymer chain can react with a cross-linking agent to generate chemical cross-linking, and finally a network structure is formed. The formed vegetable transplanting water-retaining agent has a more advanced structure and smaller pore size, and can improve the water absorption rate. The water retention is determined by the hydrogen bonding and van der waals interactions between water molecules and superabsorbent. The vegetable transplanting water-retaining agent has a more compact network structure, and a stronger network structure has higher water-retaining property. Meanwhile, the higher water absorption capacity can also improve the water retention.
Test example 3
Chlorophyll content test
The method for measuring the chlorophyll content of the lettuce seedlings in the examples and the comparative examples adopts an 80 wt% acetone aqueous solution leaching method, the lettuce seedlings which grow for 24 days are taken and leached in a shading mode for 48 hours, a TU-1900 double-beam ultraviolet-visible spectrophotometer is used for carrying out color comparison at the wavelengths of 663nm and 646nm, each sample is subjected to three tests, the test results are shown in the table 3, and the chlorophyll formula is calculated as follows:
Ca＝12.21D663-2.81D646
Cb＝20.13D646-5.03D663
CT＝Ca+Cb＝17.32D646+7.18D663
ca is the chlorophyll a content;
cb is the chlorophyll b content;
CT is the chlorophyll a + b content.
Table 3: chlorophyll content test results
The photosynthetic pigment in the plant leaves is the material basis of photosynthesis of the plants, the chlorophyll content is high, the seedling metabolism level is high, organic matters are synthesized more, and the growth is vigorous after the planting, the chlorophyll content in the embodiment 1 is the highest as can be seen from the table 3, and the water-retaining agent and the using method in the embodiment 1 can enable the seedlings to perform the chlorophyll anabolism well and promote the plant growth. Probably, the water-retaining agent of the embodiment 1 has the best water absorption and retention effect, is applied by directly dipping roots, has the best long-term water retention effect, ensures that lettuce seedlings have the lowest drought stress degree, ensures that the metabolic activity of plants is relatively vigorous and the growth of the plants is relatively fast when the free water content in the plants is higher, and has higher synthesized chlorophyll content.
Claims (8)
1. The application of the water-retaining agent for vegetable transplantation in vegetable transplantation is characterized by comprising the following specific application:
the water-retaining agent for transplanting vegetables is adopted to dip roots of the vegetables to be tested, then the vegetables are placed in planting furrows dug in open field, watering is carried out immediately after soil covering, and the roots of the vegetables are wrapped by plastic films.
2. The use of claim 1, wherein the test vegetable is lettuce.
3. The application of claim 1, wherein the root dipping method is to dip the root in a 100-fold diluent of the water-retaining agent for vegetable transplantation or dip the water-retaining agent for vegetable transplantation directly in the root.
4. The application of claim 1, wherein the preparation method of the water-retaining agent for vegetable transplantation comprises the following steps:
s1, adding chitosan powder into the 2-chloroethylamine hydrochloride aqueous solution, stirring in a water bath, and completely dissolving to obtain a chitosan derivative;
s2, adding the chitosan derivative prepared in the step S1 into NaOH aqueous solution, carrying out water bath reaction, and then carrying out freeze drying to obtain 2, 6-diamino ethyl chitosan;
s3, placing the 2, 6-diaminoethyl chitosan prepared in the step S2 into a reactor, adding water, stirring for dissolving, placing the reactor into a water bath, adding an initiator, stirring, adding maleic acid, adding a cross-linking agent aqueous solution into a reaction mixture, continuously stirring under argon, cooling to room temperature, adding a NaOH aqueous solution for regulating the pH value, stirring to generate a gel product, adding methanol into the gel product, completely dehydrating, grinding and sieving the gel particle hardened product to obtain the vegetable transplanting water-retaining agent.
5. The use of claim 4, wherein the lyophilization parameters in step S2 are as follows: pre-freezing for 3-5 h at-32 to-38 ℃, and vacuumizing and drying after freezing, wherein the drying conditions are as follows: the vacuum degree is 2-5 Pa, a primary sublimation method is adopted to gradually heat the product, the freeze-drying box plate layer is respectively kept for 2-3 hours at 0 ℃, 5 ℃, 10 ℃ and 15 ℃ to make the ice crystals of the product disappear, and then the temperature is raised to 26-30 ℃ of the drying chamber and kept for 2-3 hours.
6. The use according to claim 4, wherein the initiator in step S3 is one of azobisisobutyronitrile, di-tert-butyl peroxide and ammonium persulfate.
7. The use according to claim 4, wherein the cross-linking agent in step S3 is one of dicumyl peroxide, N-benzyl- (9Z,12Z,15Z) -octadecatriene amide, and hydroxyethyl maleate.
8. The use according to claim 4, wherein the aperture of the screen used in the screening in step S3 is 200-400 mesh.
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