Adhesion type slow-release foliar fertilizer based on pantoea polysaccharide-chitosan oligosaccharide composite gel as well as preparation process and application of adhesion type slow-release foliar fertilizer

Abstract

The invention relates to the technical field of agricultural fertilizers, in particular to an adhesive slow-release foliar fertilizer based on pantoea polysaccharide-chitosan oligosaccharide composite gel as well as a preparation process and application of the adhesive slow-release foliar fertilizer. The adhesion type slow-release foliar fertilizer is prepared from the following components in percentage by weight: 0.5 to 2.0 weight percent of pantoea polysaccharide, 0.5 to 2.0 weight percent of chitosan oligosaccharide, 10 to 30 weight percent of plant nutrient elements and the balance of deionized water. The prepared adhesion type slow-release foliar fertilizer has lower drying time and surface tension, the contact angle on crops can be remarkably reduced, and the maximum stable retention amount is increased. The foliage fertilizer has good adhesiveness on the foliage surface, has the functions of nutrient sustained and controlled release and water absorption and retention, and can prolong the residence time, reduce the fertilizer consumption and promote the yield increase of crops.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural fertilizers, and in particular to an adhesive slow-release foliar fertilizer based on a pantoea polysaccharide-chitosan oligosaccharide composite gel, and a preparation process and application thereof. Background Art

[0002] Foliar fertilizer is a type of fertilizer that applies nutrients to the surface of crop leaves and performs its functions through leaf absorption. It supplements plant nutrients and can make up for the lack of nutrient absorption by the roots. Traditional foliar fertilizers have many problems that are difficult to ignore during actual use. First, poor adhesion is a significant drawback. During the spraying process, more than 50% of the foliar fertilizer will drip from the leaf surface, which not only results in a large amount of fertilizer waste but also increases production costs. Moreover, the sprayed nutrients are easily lost by rain, resulting in low fertilizer utilization. Leached and volatilized nutrients enter the environment and may also pollute water bodies, soil, and air, affecting the balance of the ecological environment. Secondly, traditional foliar fertilizers have no slow-release properties and release nutrients too quickly. On the one hand, this can easily lead to nutrient loss, and on the other hand, multiple sprayings are required to achieve the desired effect. This is not only time-consuming and labor-intensive, but also increases farmers' labor intensity and agricultural production input costs. In addition, traditional foliar fertilizers lack moisturizing properties, and the sprayed liquid dries quickly on the leaves, affecting the crops' absorption of nutrients; under the strong direct sunlight in summer, it can easily cause crop leaf burns, thereby affecting crop yield and quality.

[0003] Therefore, developing a foliar fertilizer that has strong adhesion to the surface of crop leaves, can slowly release nutrients, and absorb and retain water can effectively solve the problems existing in traditional foliar fertilizers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an adhesive slow-release foliar fertilizer based on Pantoea polysaccharide-chitosan oligosaccharide composite gel in response to the deficiencies of the existing technology.

[0005] The technical problem that the present invention also aims to solve is to provide a preparation process for an adhesive slow-release foliar fertilizer of a Pantoea polysaccharide-chitosan oligosaccharide composite gel.

[0006] The final technical problem to be solved by the present invention is to provide application of the adhesive slow-release foliar fertilizer of Pantoea polysaccharide-chitosan oligosaccharide composite gel.

[0007] In order to solve the above technical problems, in the first aspect, the present invention discloses an adhesive slow-release foliar fertilizer based on pantothenic acid polysaccharide-chitosan oligosaccharide composite gel, which comprises the following components by weight percentage: 0.5-2.0wt% of pantothenic acid polysaccharide, 0.5-2.0wt% of chitosan oligosaccharide, 10-30wt% of plant nutrients, and the balance is deionized water.

[0008] The pantoea polysaccharide is a natural biopolymer, which is an extracellular polysaccharide secreted by Pantoea alhagi XK-11.

[0009] The pantoea polysaccharide is obtained by fermenting and sterilizing Pantoea alhagi XK-11, has a molecular weight of ≥1000kDa, and has the effects of enhancing plant resistance and promoting plant growth.

[0010] Specifically, the Pantoea alhagi XK-11 has a deposit number of CGMCC NO.15526. The strain and its extracellular polysaccharide have been disclosed in patent CN111808777B.

[0011] Furthermore, the Pantoea polysaccharide is a sterile fermentation broth containing Pantoea polysaccharide, or a pure Pantoea polysaccharide prepared after purification.

[0012] The chitosan oligosaccharide is commercially available, has a molecular weight of 400 to 2000 Da, and has the effect of inducing plant resistance.

[0013] In some embodiments of the present invention, the pantothenic acid polysaccharide and chitosan, after being mixed, have a synergistic viscosity-increasing effect to form an adhesion matrix. The mixed liquid has high adhesion on the leaf surface, which can improve leaf surface retention.

[0014] Among them, the plant nutrients can be precisely formulated according to different developmental stages and different crops, including but not limited to any one or a combination of macroelements, trace elements, and plant nutrients in the prior art that improve the nutritional value of different crops at different developmental stages are all within the scope of protection of the present invention.

[0015] Specifically, the macroelements are nitrogen, phosphorus and potassium; the microelements are calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum, chlorine, sodium and nickel.

[0016] In some embodiments of the present invention, the plant nutrients are calcium, magnesium, boron, zinc and iron.

[0017] The plant nutrient elements are all prepared using corresponding soluble compounds, and no precipitation is generated when they are prepared alone or in combination.

[0018] In a second aspect, the present invention discloses an adhesive slow-release foliar fertilizer based on a composite gel of pantoea polysaccharide and chitosan oligosaccharide. Pantoea polysaccharide is dispersed in deionized water and stirred until completely swollen. Then, chitosan oligosaccharide and plant nutrients are added and homogenized and stirred. The pH is then adjusted to 5.5-6.0 to obtain a transparent gel-like liquid foliar fertilizer, namely, the adhesive slow-release foliar fertilizer.

[0019] Wherein, the deionized water is deionized water at 50-80°C.

[0020] The homogenous stirring is carried out under the following conditions: homogenous mixing at 2000-5000 rpm for 5-15 minutes, and then stirring is continued for 1-2 hours.

[0021] In a third aspect, the present invention discloses an application of an adhesive slow-release leaf surface based on a Pantoea polysaccharide-chitosan oligosaccharide composite gel in increasing crop yield.

[0022] In some embodiments of the present invention, the adhesive, slow-release foliar fertilizer based on the Pantoea polysaccharide-chitosan oligosaccharide composite gel exhibits a shorter drying time and surface tension, significantly reducing the contact angle on crops and increasing the maximum stable retention. Spraying the fertilizer onto the leaves of various food and cash crops reduces the dosage by 50% compared to conventional commercially available water-soluble foliar fertilizers, enhancing crop resistance, reducing disease incidence, and promoting yield increases.

[0023] Beneficial effects:

[0024] 1. The present invention is based on a pantoea polysaccharide-chitosan oligosaccharide composite gel (pantoea polysaccharide and chitosan oligosaccharide form a gel through electrostatic self-assembly). The composite gel comprises the following components, calculated by weight percentage: 0.5-2.0 wt% pantoea polysaccharide, 0.5-2.0 wt% chitosan oligosaccharide, 10-30 wt% plant nutrients, and the balance deionized water. The pantoea polysaccharide and chitosan oligosaccharide have a significant synergistic viscosity-increasing effect, synergistically promoting plant growth. The resulting adhesive slow-release foliar fertilizer has good adhesion and can firmly adhere to the surface of crop leaves, reducing fertilizer dripping and loss and improving fertilizer utilization.

[0025] 2. The adhesive slow-release foliar fertilizer prepared by the present invention also has nutrient slow-release and water absorption and retention functions. The nutrient slow-release function can slowly release nutrients, avoiding rapid nutrient loss and waste, extending the fertilizer's shelf life, reducing fertilization frequency, and lowering labor costs. The water absorption and retention function can provide a moist environment for crop leaves, which is beneficial to crop nutrient absorption and can better meet the crop's water needs in arid environments, thus being more conducive to crop growth.

[0026] 3. The pantotheca polysaccharide and chitosan oligosaccharide in the adhesive slow-release foliar fertilizer prepared by the present invention are of natural origin. After the nutrient release is completed, they can be completely degraded and will not cause pollution to the environment. It is an environmentally friendly foliar fertilizer with broad industrial application prospects. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0028] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0029] Example 1: Study on the synergistic viscosity-increasing effect of Pantoea polysaccharide and chitosan oligosaccharide

[0030] Mixtures of pantothenate polysaccharide and chitosan oligosaccharide at different concentrations were prepared according to the scheme in Table 1 below, and the viscosity was measured using a rotational viscometer. The experimental design and results are shown in Table 1.

[0031] Table 1 Experimental design and results of preparing mixed solutions of Pantoea polysaccharide and chitosan oligosaccharide at different concentrations

[0032]

[0033] As shown in the table above, chitosan oligosaccharides have a relatively low molecular weight and inherently low viscosity, while pantothenic acid polysaccharides are biopolymers with naturally higher viscosity. However, when pantothenic acid polysaccharides are combined with chitosan oligosaccharides, the viscosity is significantly increased compared to pantothenic acid polysaccharides at the same concentration, indicating a synergistic viscosity-enhancing effect. Furthermore, even after a 1000-fold dilution, the chitosan oligosaccharide-pantothenic acid polysaccharide combination retains a certain viscosity. This is likely due to electrostatic crosslinking between the uronic acid carboxyl groups on pantothenic acid polysaccharides and the amino groups on chitosan oligosaccharides.

[0034] Example 2: Preparation of an adhesive slow-release foliar fertilizer based on Pantoea polysaccharide-chitosan oligosaccharide composite gel

[0035] (1) Disperse Pantoea polysaccharide in deionized water at 50-80°C and stir until completely swollen to a final concentration of 1 wt%;

[0036] (2) Add chitosan oligosaccharide (final concentration 1 wt%) and plant nutrients (calcium 8 wt%, magnesium 2 wt%, boron 0.5 wt%, zinc 0.4 wt%, iron 0.1 wt%), mix homogenously at 2000-5000 rpm for 10 min, and continue stirring for 1 hour;

[0037] (3) Use hydrochloric acid to adjust the pH to 5.5-6.0 to obtain a transparent gel-like liquid foliar fertilizer.

[0038] Example 3: Study on Drying Time and Surface Tension of Foliar Fertilizer

[0039] The foliar fertilizer prepared in Example 2 was used as the treatment group, a commercially available water-soluble foliar fertilizer containing the same plant nutrients was used as the control group, and deionized water was used as the clean water group. Both foliar fertilizers were diluted 1000 times with deionized water and tested for drying time and surface tension. The test method is as follows.

[0040] Foliar fertilizer drying time: Use a microsyringe to dispense 5 μL of diluted foliar fertilizer solution onto a flat, paraffin-coated glass slide. Observe through a binocular and record the time required for the droplet to completely dry at 26°C and 60% relative humidity. This is the foliar fertilizer drying time. Repeat the measurement five times for each treatment, and average the results.

[0041] Determination of surface tension of foliar fertilizer: Use BZY-3B surface tension meter to measure the surface tension values of different foliar fertilizer dilutions in turn. Repeat the measurement 5 times for each treatment and take the average value of the results.

[0042] The drying time and surface tension results of the foliar fertilizer are shown in Table 2 below.

[0043] Table 2 Drying time and surface tension measurement results of foliar fertilizer

[0044] Drying time (min) Surface tension (mN / m) Clean water group: deionized water 50.9 54.9 Control group: ordinary water-soluble foliar fertilizer available on the market 51.7 54.3 Treatment group: Example 2 foliar fertilizer 40.2 41.9

[0045] It can be seen from the results in the above table that, compared with ordinary water-soluble foliar fertilizers on the market, the foliar fertilizer prepared by the present invention has a lower drying time and surface tension, which is related to the fact that Pantoea polysaccharide, as a biopolymer, has good film-forming and ductility.

[0046] Example 4: Study on the contact angle and maximum stable retention of foliar fertilizer on leaves

[0047] In this example, corn leaves were cut from a corn field in Xiyangshe Village, Tianbao Town, Tai'an City, Shandong Province on August 3, 2024, and the contact angle and retention were measured. The specific test method is as follows.

[0048] Contact Angle Measurement: Cut an appropriate size of corn leaf, avoiding the veins and ensuring the surface structure is intact, and attach it evenly to a glass slide using double-sided tape. Use a contact angle meter to measure the contact angle of different foliar fertilizers on the corn leaf surface. The time from sample addition to recording the measurement result should be within 5 seconds. Each treatment should be repeated 5 times, and the results are averaged.

[0049] Determination of maximum stable retention: Cut corn leaves of a certain size, measure the area of the leaves (S) with a YMJ-A leaf area meter, and weigh the mass of the leaves (m o ), then use tweezers to hold the leaves and put them into the foliar fertilizer dilution for 5 seconds, then take them out vertically. When there is no foliar fertilizer dilution dripping on the leaves, weigh the mass (m1) again and calculate the mass according to the formula R m =(m1-m0) / 2S to calculate the maximum stable retention of foliar fertilizer R m (Unit mg / cm 2 Each treatment was repeated 5 times and the results were averaged.

[0050] The results of the contact angle and the maximum stable retention of the foliar fertilizer on the leaf surface are shown in Table 3 below.

[0051] Table 3 The results of contact angle and maximum stable retention of foliar fertilizer on leaf surface

[0052] contact angle <![CDATA[Maximum stable retention amount (mg / cm 2 )]]> Clean water group: deionized water 90.1° 3.01 Control group: ordinary water-soluble foliar fertilizer available on the market 89.7° 3.47 Treatment group: Example 2 foliar fertilizer 65.6° 6.98

[0053] As can be seen from the table above, the foliar fertilizer prepared by the present invention spreads more easily on the leaf surface, significantly reducing the contact angle on the corn leaves, creating favorable conditions for the effective absorption of subsequent foliar fertilizer. At the same time, the maximum stable retention in the treated group increased by 101% compared to the control group. This means that the foliar fertilizer prepared by the present invention can adhere to more active ingredients on the corn leaves, providing more sufficient nutrients for the plant, helping to improve the utilization efficiency and fertilization effect of the foliar fertilizer.

[0054] Example 5: Evaluation of the application effect of an adhesive slow-release foliar fertilizer based on Pantoea polysaccharide-chitosan oligosaccharide composite gel

[0055] The experiment was conducted at the Nanjing Tech University test site from June to September 2024. The test soil was garden soil, and the test fertilizers were the foliar fertilizer prepared in Example 2 and a commercially available ordinary water-soluble foliar fertilizer (nutrient elements were the same as in Example 2). The test crop was Chinese cabbage (Dongbai No. 1).

[0056] The randomized block method was used for comparative experiment in field plots. The plot area was 12m 2 The row spacing was 60cm×40cm, and a 1m protection row was set between plots. 500kg / hm2 of high-quality organic fertilizer was applied to each treatment. 2 , diammonium phosphate 150kg / hm 2 Use as base fertilizer. Topdress twice, apply urea 150kg / hm2 during the rosette stage (10-12 leaves). 2 In the early stage of heading, apply urea 200kg / hm 2 , potassium sulfate 150kg / hm 2 The foliar fertilizer of the present invention and commercially available foliar fertilizer were diluted 1000 times and then sprayed, and a clear water control was set at the same time. Cabbage was sown on June 15 and planted on July 2. Liquid foliar fertilizer was sprayed starting from the rosette stage, and the spraying method is shown in Table 4 below. The effects of different foliar fertilizer spraying treatments on cabbage yield are shown in Table 5 below.

[0057] Table 4 Foliar fertilizer spraying method

[0058] Processing number fertilizer Spraying method 1 Clean water group: deionized water Spray once every 7 days, a total of 4 times 2 Control group: ordinary water-soluble foliar fertilizer available on the market Spray once every 7 days, a total of 4 times 3 Treatment group: Example 2 foliar fertilizer Spray once every 7 days, a total of 4 times 4 Treatment group: Example 2 foliar fertilizer Spray once every 10 days, for a total of 3 times 5 Treatment group: Example 2 foliar fertilizer Spray once every 14 days, spray twice in total 6 Treatment group: Example 2 foliar fertilizer Spray once every 28 days, spray once in total

[0059] Table 5: Effects of different foliar fertilizer spraying treatments on cabbage yield

[0060] Processing number Plot yield kg Yield increase 1 <![CDATA[108.67 e ]]> —— 2 <![CDATA[120.92 c ]]> 11.3％ 3 <![CDATA[124.31 a ]]> 14.4％ 4 <![CDATA[122.14 b ]]> 12.4％ 5 <![CDATA[120.19 c ]]> 10.6％ 6 <![CDATA[110.39 d ]]> 1.6％

[0061] As can be seen from the above table, the foliar fertilizer prepared by the present invention has a higher yield increase rate than the commercially available foliar fertilizer, and when the application amount of the foliar fertilizer of the present invention is reduced by 50%, the yield increase effect is not significantly different from that of the commercially available foliar fertilizer, indicating that the foliar fertilizer of the present invention can significantly reduce the amount of fertilizer used, thereby playing the role of reducing the amount of fertilizer and increasing the efficiency.

[0062] The present invention provides an adhesive, slow-release foliar fertilizer based on a pantoea polysaccharide-chitosan oligosaccharide composite gel, as well as a process for its preparation and application. While there are numerous methods and approaches for implementing this technical solution, the foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. An adhesive slow-release foliar fertilizer based on Pantoea polysaccharide-chitosan oligosaccharide composite gel, characterized in that: The composition comprises the following components by weight percentage: 0.5-2.0 wt% of pantoea polysaccharide, 0.5-2.0 wt% of chitosan oligosaccharide, 10-30 wt% of plant nutrient elements, and the balance is deionized water.

2. The adhesive slow-release foliar fertilizer according to claim 1, characterized in that The pantoea polysaccharide is an extracellular polysaccharide secreted by Pantoea alhagi XK-11.

3. The adhesive slow-release foliar fertilizer according to claim 2, characterized in that The pantoea polysaccharide is obtained by fermenting and sterilizing Pantoea alhagi XK-11, and its molecular weight is greater than or equal to 1000 kDa.

4. The adhesive slow-release foliar fertilizer according to claim 1, characterized in that The molecular weight of the chitosan oligosaccharide is 400-2000Da.

5. The adhesive slow-release foliar fertilizer according to claim 1, characterized in that The plant nutrient elements are any one or a combination of macroelements, microelements, and trace elements; Among them, the macroelements are nitrogen, phosphorus and potassium; the microelements are calcium, magnesium, sulfur, iron, manganese, zinc, copper, boron, molybdenum, chlorine, sodium and nickel.

6. The adhesive slow-release foliar fertilizer according to claim 5, characterized in that The plant nutrient elements are all prepared using corresponding soluble compounds, and no precipitation is generated when they are prepared alone or in combination.

7. The method for preparing the adhesive slow-release foliar fertilizer according to any one of claims 1 to 6, characterized in that: Pantoea polysaccharide is dispersed in deionized water, stirred until completely swollen, and then chitosan oligosaccharide and plant nutrient elements are added and homogenized and stirred; and then the pH is adjusted to 5.5-6.0 to obtain the adhesive slow-release foliar fertilizer.

8. The preparation method according to claim 7, characterized in that The deionized water is deionized water at 50-80°C.

9. The preparation method according to claim 7, characterized in that The homogenous stirring is carried out under the following conditions: homogenous mixing at 2000-5000 rpm for 5-15 minutes, and then stirring is continued for 1-2 hours.

10. Use of the adhesive slow-release foliar fertilizer according to any one of claims 1 to 6 in increasing crop yield.

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