WO2021012062A1 - Method for obtaining a homogeneous acidic chitosan–silicon solution that is stable in the short term, which comprises preparing an acidic chitosan solution at a concentration of 2-20% by weight chitosan and an acidic silicon solution at a concentration of 2-30% silicon - Google Patents

Abstract

The invention relates to a method for obtaining a homogeneous acidic chitosan–silicon solution that is stable in the short term, provides biopesticidal, biofertiliser and biostimulant properties, systemic acquired resistance (SAR) effect and plant tolerance to stress conditions, and incorporates a homogeneous acidic chitosan–silicon solution comprising: (a) an acidic chitosan solution at a concentration of 2-20% by weight chitosan and (b) an acidic silicon solution at a concentration of 2-30% by weight silicon. The method includes the steps of: (1) producing the chitosan solution; (2) producing the silicon solution; and (3) producing chitosan–silicon.

Description

DESCRIPTIVE MEMORY

METHOD OF OBTAINING AN ACID AND HOMOGENEOUS CHITOSAN-SILICON SOLUTION IN THE SHORT-TERM STABLE THAT INCLUDES; PREPARE AN ACID SOLUTION OF CHITOSANE IN A WEIGHT CONCENTRATION OF

2-20% OF CHITOSANE AND AN ACID SOLUTION OF SILICON IN A CONCENTRATION OF 2-30% OF SILICON.

The invention described corresponds to a method for obtaining an acidic and homogeneous solution of chitosan at 2-20% and silicon acid at 2-30% stable in the short term. This composition has properties of biopesticide, biofertilizer, biostimulant, SAR effect (Acquired Systemic Resistance) and tolerance of the plant against stress conditions, which enhances both the growth of the plant and the prevention of infections from pathogens and a better postharvest.

STATE OF THE ART:

DESCRIPTION OF THE KNOWN

Agriculture in Chile is one of the most diverse, profitable and culturally important economic activities in the country, due to its great geographical, climatic and cultural variety, which allows it to generate a great variety of agricultural products. Among the main Chilean agricultural products are grapes, apples, cherry trees, walnut trees, pears, blueberries, avocados, citrus fruits, crops and vegetables [1]. These crops are diversified throughout the country, and in different plantations up to 20 plant species can be found together. According to the export data for 2017 from the OEC, the sale of agricultural products of fruits and vegetables represented 10% of the transactions carried out in the country, with a total of USD 7.23 billion. Chile is a major exporter of fresh fruit to the rest of the world where it faces the requirements of an increasingly demanding global market in terms of quality and the use of chemical synthesis pesticides, restricting their use every day.

For an efficient crop, it is necessary to have the right conditions for its growth, productivity and quality. Mainly, these involve the control of agroclimatic factors such as temperature and humidity, water and soil type, and soil nutrients such as organic carbon, nitrogen, potassium, phosphorus, among others. These are constantly monitored for the optimal growth and production of the product of interest, be it fruit or vegetable. In addition, it is necessary to control the presence of pathogens such as insects, bacteria and fungi and weeds, which lead to the death of crop plants and a reduction in production per harvest cycle. Perhaps the most relevant case for the country is the infections of table grape vines caused by the fungus Botrytis cinerea, which annually causes an average loss of up to 20% of crops in pre and post harvest [2 ]

Current methodologies for pest control and optimal plant growth involve the use of pesticides (insecticides, acaricides, fungicides, bactericides, nematicides and herbicides) applied at certain times and in specific cases such as high humidity or rain. Without However, these can generate resistance to chemical agents, which implies a higher use of application rates. This can generate environmental and health problems, since these chemical agents have different degrees of toxicity, a low rate of degradation, have a high level of remanence in plants and in the soil, where it is possible that they leak into groundwater, polluting aquifer reserves and being a potential danger to human and wild life [3].

Therefore, various alternative methods have been developed to control pests, diseases and plant growth that do not have these associated detrimental effects and maintain similar effectiveness. In the current state of the art, chitosan and acid silicon are mainly used, plus additives, such as biopesticide and growth stimulator of the plant and its fruits, to carry out the function of the previously mentioned pesticides. Despite the simplicity of its formulation, there is a great variety of patents and literature regarding the mechanism of action and with different concentrations, with different scenarios.

There is a 20% aqueous chitosan solution, in conjunction with Xianzhuli oil and hydroxypropylcellulose and other natural additives, which is of natural origin and has a biological hormonal function in the plant to stimulate growth and protection against pathogens. Chitosan is prepared by adding chitin to an aqueous solution, where chitosan is generated, dissolved, and concentrated in suspension by adding the enzyme chitin deacetylase, which converts chitin to chitosan. The chitosan remains in solution after the incorporation of the other additives with constant moderate stirring (CN102067888B). There are also methodologies for preparing highly concentrated chitosan solutions, up to 20% by weight, in an acidic medium. This was done by generating an aqueous solution of chitosan and acetic acid in excess water. The aqueous solution is then slowly evaporated with moderate stirring, adding salts such as sodium chloride, potassium chloride, among others, as an additive in order to reduce the viscosity of the solution, until reaching 8-20% chitosan in solution. . (W02009035413A1).

In Chile, there are several patents related to the use of chitosan for pest control and optimization of plant growth. The following can be highlighted: the use of a biological pesticide consisting of an entomopathogenic nematode, Chitosan and a weak acid, by IDEBIO, S.L., to increase the resistance of plants to pests (CL 2703-2001); formation of antifouling paint from chitosan, iron and copper minerals and acetic acid to prevent initial adhesion of pathogens (CL 2791-2008); use of copper nanoparticles coated with chitosan and / or alginate, antibacterial peptides, plus additives, for the prevention of infection by pathogens in plants (CL 3334-2016); among others of similar formulation with the same purpose to protect the plant from foreign infections.

There are also formulations that use a chitosan-silicon mixture, where it is used as an adsorbent for heavy metals in which are inoculated, such as mercury, lead, among others (CN104045857B). There is a similar formulation in the literature called NanoChisil, which is a mixture between silicon and chitosan for use as a fertilizer in corn crops to improve production. This allows the reduction of the use of traditional fertilizers as a substitute, from natural and low-cost sources [4]

DETAILED DESCRIPTION OF THE INVENTION.

The invention described corresponds to a method for obtaining a (a) acidic and homogeneous solution of chitosan at 2-20% in water, and (b) acid silicon at 2-30% stable in the short term. This composition has properties of biopesticide, biofertilizer, biostimulant, SAR effect and tolerance of the plant against stress conditions, which enhances both the growth of the plant and the prevention of infections from pathogens and a better postharvest.

The method is made up of the steps mentioned below:

one . CHITOSAN SOLUTION:

Chitosan is a polymer processed from chitin, obtained from the exoskeletons of insects, shrimp, crabs, among others. This has a biostimulatory effect on plant growth and as a biopesticide. The chitosan solution at 2-20% by weight is obtained by gradually dissolving deacetylated chitosan in a solution of an acid and water at an acidic pH. Chitosan dissolves progressively in an aqueous solution at acidic pH and the acid acts as an additional effective solvent. The obtained mixture becomes homogeneous after moderate stirring for about 1 hour at room temperature, the undissolved suspended solids are filtered and a viscous clear solution is obtained as the product.

2. SILICON SOLUTION:

Potassium silicate is a mineral that precipitates under acidic conditions, polymerizing in chains of silicon oxide (quartz). Sodium silicate is not used since sodium is an unwanted mineral in agriculture. To obtain an acidic silicon solution, 100% silicon silica is used as raw material. It is formulated 2-30% dissolved in water at pH 4, an aqueous solution is produced at pH 4 using an acid as an acidifying agent. Additives such as ethyl alcohol and propylene glycol are added to this solution to prevent the precipitation of silicon at acidic pH. Then, it is stirred moderately for 30 minutes to 1 hour at room temperature to homogenize the mixture, and not to generate nucleation sites and to start polymerizing. 3. SILICON-CHITOSANE SOLUTION:

Once both solutions have been obtained at pH 4 separately, the solutions of chitosan 2-20% and silicon 2-30% are mixed in a volumetric ratio of 1: 1. The final mixture is homogenized by moderate stirring for 30 minutes to 1 hour at room temperature, filtered the solid undissolved particles and leave it to rest for 2 hours. In case of formation of new granules, the mixture is again shaken, filtered and settling until no more granules are generated in the short term. The final solution is packaged and stored in the cellar.

The methodology is effective regarding the difficulty of generating and maintaining a stable solution from the mixture of solutions at a high concentration of silicon and chitosan. The mixture obtained from both products allows the dissolution of silicon and chitosan at an acidic pH and stable and fluid enough to be worked using the proposed methodology, in the short term.

The main use of this aqueous mixture of silicon-chitosan is to be a biopesticide, biostimulant, biofertilizer, SAR effect in plants and greater tolerance under stress conditions, achieving a firmer, healthier fruit with better postharvest condition.

When used and applied to the foliage, this product adheres to the cell walls of the cuticular and subcuticular layers, forming a silicon oxide (quartz) film, which provides firmness and elasticity to the treated tissues. Together with chitosan, they form a barrier that reduces dehydration, photo-oxidation and controls the entry of certain microorganisms into the plant. This control is carried out directly and by artificially activating the elicitor effect of the plant or SAR, where the chitosan molecule acts as a hormonal signal that indicates the presence of localized damage in the area of application of the plant, both mechanically and by pathogenic microbial agents. The plant responds to this signal by activating its immune system, generating compounds or enzymes with antimicrobial activity, which consequently reduces the damage caused by these microorganisms. This allows the cultivation of plants to have a better state of health and increases the yield of the crops and their post-harvest condition.

BACKGROUND TO THE STATE OF THE ART:

[1] Central Intelligence Agency (CIA) (2011). "Field Listing: Agriculture - Products" (HTML). The World Factbook. Retrieved April 19, 201 1.

[2] http://www.mundoaaropecuario.cl/new/2018/07/09/desarrollan-biofunaicida- para-combat-pudricion-de-la -fruit /

[3] Flint, M. L. 1998. Pests of the Garden and Small Farm. Oakland: Univ. Calif. Div. Agrie. Nat. Res. Publ. 3332.

[4] Gumilar, T.A. & Prihastanti, Erma & Haryanti, S & Subagio, Agus &

Ngadiwiyana, Ngadiwiyana. (2017). Utilization of waste silica and chitosan as fertilizer nano chisil to improve corn production in Indonesia. Advanced Science Letters. 23. 2447-2449. 10.1 166 / asl.2017.8732.

[5] CN 102067888 B. 2010.

[6] WO 2009035413 A1. 2008. Renbi Bai, Wei Han

[7] CL 2703-2001. 2001. Martínez Peña Alejandro.

[8] CL 2791-2008. 2008. Cárdenas Triviño Galo.

[9] CL 3334-2016. 2016. Kogan Marcelo et al.

[10] CN 104045857 B. 2014.

Claims

1.- Method of obtaining an acidic and homogeneous solution of chitosan-silicon stable in the short term, which provides biopesticidal, biofertilizing, biostimulant, SAR effect (Systemic Acquired Resistance) and tolerance of the plant against stress conditions. CHARACTERIZED because it incorporates an acid and homogeneous solution of silicon chitosan that comprises; (a) preparing an acid solution of chitosan in a concentration by weight of 2-20% of chitosan and (b) an acidic solution of silicon in a concentration by weight of 2-30% of silicon; in which said preparation includes three stages: stage (1) elaboration of the chitosan solution, step (2) elaboration of the silicon solution and step (3) elaboration of chitosan-silicon. 2.- Method for obtaining an acidic and homogeneous solution of chitosan-silicon stable in the short term according to claim 1 CHARACTERIZED because in step (1) the 2-20% chitosan solution to water is obtained by gradually dissolving chitosan deacetylated in a solution of an acid and water at acidic pH, where the chitosan progressively dissolves in an aqueous solution at acidic pH and the acid acts as an additional effective solvent, the mixture obtained becomes homogeneous after moderate stirring for 30 minutes at 1 hour at room temperature, then the undissolved suspended solids are filtered and a viscous clear solution is obtained as the product. 3.- Method of obtaining an acidic and homogeneous solution of chitosan-silicon stable in the short term according to claims 1 and 2 CHARACTERIZED because in step (2) the 2-30% silicon solution dissolved in water at pH 4 produces a aqueous solution at pH 4 using an acid as acidifying agent, additives such as ethyl alcohol and propylene glycol are added to said solution to avoid the precipitation of silicon at acid pH, then it is stirred moderately for 30 minutes to 1 hour at room temperature to homogenize the mixing, and not generating nucleation sites and starting to polymerize. 4.- Method of obtaining an acidic and homogeneous solution of chitosan-silicon stable in the short term according to previous claims CHARACTERIZED because in step (3) both solutions at pH 4 are mixed in a volumetric ratio of 1: 1; The final mixture is homogenized by moderate stirring for 30 minutes to 1 hour at room temperature, the undissolved solid particles are filtered and left to stand for 2 hours, in case of formation of new granules, the mixture is stirred again, filtered and rest until no more granules are generated in the short term, the final solution is packaged and stored in the cellar.