Composition of chelates of amino acids derived from a keratin hydrolysate high in free amino acids with at least one mineral nutrient and use thereof in agriculture

Abstract

The invention relates to a composition of at least one chelate of amino acids derived from a particular keratin hydrolysate with at least one mineral nutrient, wherein the particular hydrolysate comprises at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, and the mineral nutrient is selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper, to a process for preparing said composition and to uses thereof, particularly in agriculture as plant biostimulants.

Description

Composition of amino acid chelates derived from a keratin hydrolysate with high levels of free amino acids, containing at least one mineral nutrient, and their use in agriculture

[0001] [Field of invention]

[0002] The invention relates to a composition of amino acid chelates derived from a keratin hydrolysate with a high content of free amino acids and at least one mineral nutrient. More particularly, the invention relates to the use of this chelate composition in agriculture, especially as plant biostimulants.

[0003] State of the art

[0004] To grow, develop, and bear fruit, a plant needs water, light, and nutrients. Plants draw the essential elements for their growth, such as macro- and micro-elements, from the soil. Each plant species has specific needs, so to avoid the consequences of deficiencies, it is necessary to find a good balance among all the nutrients.

[0005] It is also known that sensitivity to deficiencies varies considerably depending on the plant in question: in a state of deficiency, some plants will nevertheless develop and produce products while other plants will not develop at all.

[0006] When nutrients available in the soil are insufficient, they can be supplied in the form of inputs; however, it has been observed that, even in the presence of appropriate nutrients, plant absorption of said nutrient(s) is not always efficient.

[0007] Moreover, depending on their composition, some commercial products have the disadvantage of being aggressive towards the seedling, or even the environment.

[0008] Consequently, there remains a continued need for new, effective products that allow for better nutrient absorption by the plant, a reduction in the quantity of mineral inputs or plant protection products, in particular a reduction overdosed products. Furthermore, there remains a continued need for products that are environmentally friendly and derived from the circular economy.

[0009] It is also advantageous to have products with a moderate nitrogen content that stimulate plant development, protect against abiotic stresses, and enhance performance, particularly in terms of improved harvest quality and yield, while remaining effective on various crop types. This need is addressed by the present invention, which specifically relates to a composition of amino acid chelates derived from a specific keratin hydrolysate and at least one mineral nutrient.

[0010] The Applicant's patent application WO2019 / 043128 A1 describes a keratin hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remaining amino acids in the hydrolysate being in the form of peptides having a molecular mass of 800 Daltons or less. This hydrolysate comprises L-cystine in a content of 4 to 6% by weight, cysteine ​​in a content of 0.1% or less by weight, and tyrosine in a content of 0.6% or less. This patent application does not describe the preparation of chelates with mineral nutrients obtained from this hydrolysate.

[0011] Summary of the invention

[0012] The present invention relates to a composition of at least one amino acid chelate of a hydrolysate with at least one mineral nutrient, wherein the hydrolysate is a keratin hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remainder of the amino acids in the hydrolysate being in the form of peptides having a molecular mass less than or equal to 800 Daltons, said hydrolysate comprising from 2 to 12% by weight of peptides of 2, 3, 4 amino acids having a molecular mass less than or equal to 800 Daltons by weight relative to the total weight of the hydrolysate, said hydrolysate having the following composition in total amino acids: an aspartic acid content of 5 to 8% by weight; a threonine content of 3 to 6% by weight; a serine content of 9 to 14% by weight; a glutamic acid content ranging from 8 to 13% by weight;a glycine content ranging from 6 to 9% by weight; an alanine content ranging from 4 to 6% by weight; a valine content ranging from; 6 to 10% by weight; a methionine content of 0.1 to 0.6% by weight; an isoleucine content of 4 to 6% by weight; a leucine content of 6 to 9% by weight; a phenylalanine content of 2 to 5% by weight; a lysine content of 1 to 3% by weight; a histidine content of 0.4 to 1% by weight; an arginine content of 5.5 to 6.5% by weight; a proline content of 8.5 to 11% by weight; a tryptophan content of less than 0.1%, relative to the total weight of total amino acids in the hydrolysate; and the mineral nutrient being selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, potassium, cobalt, and copper.

[0013] Classically, the total amino acid composition is calculated relative to the dry matter of the hydrolysate.

[0014] Furthermore, in the field of the invention, it is always advantageous to have readily available processes that are simple to implement and lead to the production of undegraded hydrolysates. The process for preparing the composition according to the invention, which does not involve basic hydrolysis, meets this need.

[0015] The present invention also relates to a method for preparing the composition according to the invention, said method comprising at least one step of mixing the particular hydrolysate, defined in the paragraph above, with at least one mineral nutrient selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, potassium, cobalt, and copper, preferably in the form of hydrated sulfate(s), said mixing step being carried out under agitation for a period of 1 to 3 hours. Preferably, in said method of preparing the composition according to the invention, the hydrolysate is prepared from an animal keratinous material, preferably poultry, according to a preparation method comprising at least the following steps, in this order: - subject the keratinous material to at least one acid hydrolysis, carried out in two stages: -a first hydrolysis carried out at a temperature ranging from 60 to 80°C for a period of 4 to 5 hours then -a second hydrolysis carried out at a temperature ranging from 100 to 115°C for a period ranging from 5 to 7 hours, the two hydrolyses being able to be carried out without an intermediate pause or in performing an intermediate rest period of between 1 hour and 7 days - extract the tyrosine and cystine from said hydrolysate preferably by means of a base; - desalinate the liquid phase obtained after the extraction of the cystine and tyrosine; - concentrate the desalinated liquid phase to obtain an aqueous composition comprising 45 to 60% by weight of keratin hydrolysate in solid form relative to the total weight of said composition.

[0016] An advantage of the present invention is that the process for preparing the composition according to the invention is simple to implement since it can be implemented by mixing an acid hydrolysate with one or more nutrient(s).

[0017] Another advantage of the process according to the present invention is that the same hydrolysate can be used to prepare stable compositions with a good amino acid balance and highly satisfactory biostimulant properties using very different mineral nutrients. However, the current trend is to offer biostimulant products with very different compositions, obtained through different processes, depending on the target plant. The composition according to the invention, which can include nutrients of different natures but with a common structure, allows for process streamlining. The process is therefore particularly advantageous because the same equipment can be used to prepare the different compositions according to the invention.

[0018] The present invention further aims at the use of this composition in agriculture, preferably as a plant biostimulant.

[0019] In particular, the present invention aims at the use of the composition according to the invention as a biostimulant for plants selected from among field crops, vines, arboriculture, market gardening, medicinal and aromatic plants (PPMA), ornamental crops.

[0020] More specifically, the invention relates to the use of the composition according to the invention to improve the absorption of mineral nutrients and amino acids by the plant and to reduce the amount of mineral inputs.

[0021] Indeed, it has been shown that the composition of chelates according to the invention improves the absorption of mineral nutrients supplied by these chelates and also the absorption of mineral nutrients present in the soil.

[0022] Thus, one advantage of the composition according to the present invention is that it allows good assimilation by the plant of nutrients present in the environment of said plant, particularly in the soil, but not present in said composition according to the present invention.

[0023] More specifically, the invention relates to the use of the chelate composition according to the invention to stimulate plant development, to increase root biomass as well as leaf biomass, to improve plant size.

[0024] The composition of chelates according to the invention also makes it possible to improve crop yields.

[0025] The hydrolysate used in the composition according to the present invention is distinguished by its high content of free amino acids and also by the presence of 2 to 12% by weight of peptides of 2, 3, 4 amino acids having a molecular mass less than or equal to 800 Daltons by weight relative to the total weight of the hydrolysate.

[0026] The use of the chelate composition according to the invention is part of the search for more sustainable and resilient agriculture: chelates can be used in quantities much lower than the quantities used for fertilizers.

[0027] Indeed, without wishing to be linked to any theory, the composition of chelates according to the invention is not intended to provide nutrients such as carbon, nitrogen, potassium, phosphorus for plants but rather to allow the young plant to increase its capacity to assimilate both amino acids, and macro- and micro-elements.

[0028] The use of the chelate composition according to the invention thus makes it possible to reduce soil fertilization. Its use therefore indirectly benefits the soil by reducing the need for inputs, plant protection products, and conventional chemical fertilizers.

[0029] In particular, the use of the composition according to the invention makes it possible to significantly reduce the doses of certain mineral nutrients while maintaining the effectiveness of a full dose of these nutrients in conventional form.

[0030] Other aspects, advantages, and properties of the invention will become clear from the description, in particular from the examples that follow, which are indicative and in no way limiting.

[0031] Detailed description

[0032] Chelate composition

[0033] The present invention relates to a composition of amino acid chelates of a particular keratin hydrolysate with at least one mineral nutrient.

[0034] For the purposes of this text, "chelation" means the formation of a complex between one or two amino acid(s) (the ligand) and a mineral nutrient (the metal cation) in which the mineral nutrient is attached to the amino acid by at least two coordination bonds.

[0035] In the present invention, the chelation of mineral ions occurs with free amino acids, but also with small peptides (of 2, 3, or 4 amino acids). The degree of chelation of the mineral ion, that is, the ratio between chelated ions and total ions (chelated + unchelated), depends on the amino acid and the metal ion present.

[0036] Keratin hydrolysate

[0037] The keratin hydrolysate used according to the present invention, also referred to as the "particular hydrolysate" in this text, is distinguished by its high level of amino acids in free form: at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remainder also being in highly hydrolyzed form since the remainder of the amino acids in the hydrolysate is in the form of small peptides having a molecular mass less than or equal to 800 Daltons.

[0038] Without wanting to be linked to a theory, it appears that the presence of small peptides in this particular hydrolysate, especially dipeptides and tripeptides, also allows for additional chelation with mineral nutrients.

[0039] This composition was established using an HPLC analysis method on a gel permeation column, which allows for the determination of the molecular weight distribution of products containing proteins and / or peptides and / or free amino acids. The sample is dissolved: the molecular weight distribution is carried out on the soluble part of the products to be analyzed. The hydrolysate used in the present invention is completely soluble in water at the concentrations required for the analysis. The sample is then injected into an HPLC system, followed by UV detection. The separation of the different compounds is based on their molecular size.

[0040] Advantageously, the hydrolysate used according to the present invention is obtained from natural keratinous materials of animal origin, particularly poultry, advantageously from poultry feathers. Examples of poultry include hens, especially laying hens, chickens, turkeys, ducks, geese, etc. The natural keratinous materials may also be selected from animal hair, particularly pig bristles, animal hooves, and animal nails.

[0041] In particular, advantageously the hydrolysate used according to the present invention is not obtained from human keratin such as hair.

[0042] The hydrolysate used in the composition according to the invention is a keratin hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remaining amino acids in the hydrolysate being in the form of peptides having a molecular mass less than or equal to 800 Daltons, said hydrolysate having the following composition in total amino acids: an aspartic acid content of 5 to 8% by weight, preferably of 6 to 7% by weight; a threonine content of 3 to 6% by weight, preferably of 4 to 5% by weight; a serine content of 9 to 14% by weight, preferably of 10 to 12% by weight; a glutamic acid content of 9 to 11% by weight; a glycine content of 6 to 9% by weight, preferably of 6.5 to 8% by weight; an alanine content ranging from 4 to 6% by weight, preferably from 4 to 5% by weight;a valine content of 6 to 10% by weight, preferably 6.5 to 8% by weight; a methionine content of 0.1 to 0.6% by weight; an isoleucine content of 4 to 6% by weight, preferably 4 to 5% by weight; a leucine content of 6 to 9% by weight, preferably 7 to 8% by weight; a phenylalanine content of 2 to 5% by weight; a lysine content of 1 to 3% by weight; a histidine content of 0.4 to 1% by weight; an arginine content ranging from 5.5 to 6.5% by weight; a proline content ranging from 8.5 to 11% by weight, a tryptophan content of less than 0.1%, preferably 0% by weight relative to the total weight of total amino acids in the hydrolysate.

[0043] Amino acids are measured according to a method adapted from EC regulation 152 / 2009.

[0044] According to this method, to determine the quantities of total amino acids, hydrolysis using an acid is carried out beforehand.

[0045] For the determination of the quantities of free and total amino acids, the amino acids are separated by chromatography (“HPLC” or “HPLC” in English) preferably with ion exchange column and quantified by reaction with ninhydrin and photometric detection generally at 570 nm.

[0046] According to a preferred variant, the hydrolysate comprises the following free amino acids: at least 95% free aspartic acid by weight relative to the total weight of aspartic acid in the hydrolysate; at least 95% free threonine by weight relative to the total weight of threonine in the hydrolysate; at least 95% free serine by weight relative to the total weight of serine in the hydrolysate; at least 93% free glutamic acid by weight relative to the total weight of glutamic acid in the hydrolysate; at least 93% free glycine by weight relative to the total weight of glycine in the hydrolysate; at least 93% free alanine by weight relative to the total weight of alanine in the hydrolysate; at least 95% of methionine in free form by weight relative to the total weight of methionine in the hydrolysate;at least 93% of phenylalanine in free form by weight relative to the total weight of phenylalanine in the hydrolysate; at least 95% of proline in free form by weight relative to the total weight of proline in the hydrolysate.

[0047] As shown in Table 1, many amino acids are at least 95% in free form relative to the total weight of said amino acid in the hydrolysate.

[0048] The free amino acids are in their natural, undenatured L (levorotatory) configuration, thus readily available to soil microorganisms and plants. Furthermore, the hydrolysate used according to the invention has high levels of free branched-chain amino acids: valine, leucine, and isoleucine. These branched-chain amino acids are known to be more difficult to release under identical implementation conditions.

[0049] Advantageously, the total amino acid content (free and bound) of the hydrolysate used according to the invention, i.e., the active substance of the hydrolysate, ranges from 20% to 95% by weight relative to the total weight of the hydrolysate, the hydrolysate further comprising mineral matter and water. As already mentioned, the amino acids of the hydrolysate used in the invention are essentially free amino acids.

[0050] The hydrolysate used to form the chelate composition according to the invention also comprises small peptides, the percentage of small peptides—having a molecular mass less than or equal to 800 Daltons—in the hydrolysate ranging from 2 to 12% by weight relative to the total weight of the hydrolysate. Within this fraction, the most abundant peptides are those with the lowest mass.

[0051] As mentioned above, small peptides, particularly those of 2 to 3 amino acids, have a very good chelating capacity for mineral ions. Therefore, their presence in a hydrolysate increases the hydrolysate's ability to chelate these ions, compared to a hydrolysate that does not contain them.

[0052] Preferably, the mineral content of said hydrolysate, preferably sodium or potassium chloride, phosphate or sulfate, is less than or equal to 9% by weight, preferably less than 8% by weight, relative to the total weight of the hydrolysate. This mineral content is determined after calcination of the hydrolysate at 550°C for 4 hours.

[0053] The hydrolysate used according to the invention is also water-soluble; indeed, 1 g of hydrolysate is soluble in 5 ml of water. This is because the hydrolysate contains a very high proportion of water-soluble amino acids, both by number and weight. Furthermore, the low levels of cystine and tyrosine in the preferred hydrolysate also contribute to its high water solubility. This instant solubility is an advantage for farmers using the hydrolysate in liquid form, as it eliminates all the practical problems encountered during spraying, particularly sprayer nozzle clogging.

[0054] The hydrolysate can be used in dry form or as an aqueous composition, known as a "concentrated composition", comprising 45 to 60% of weight of keratin hydrolysate in solid form (i.e. in dry matter equivalent) relative to the total weight of said composition or in the form of an aqueous composition, known as "diluted composition", comprising 20 to 28% by weight of keratin hydrolysate in solid form (i.e. in dry matter equivalent) relative to the total weight of said composition.

[0055] Preferably, the hydrolysate is used in the form of an aqueous composition comprising 45 to 60% by weight of keratin hydrolysate in solid form relative to the total weight of said composition

[0056] The mineral nutrients used

[0057] The composition according to the present invention comprises at least one mineral nutrient selected from the group consisting of iron (Fe), zinc (Zn), manganese (Mn), magnesium (Mg), calcium (Ca), molybdenum (Mo), potassium (K), cobalt (Co), and copper (Cu). More particularly, iron (Fe), magnesium (Mg), calcium (Ca), and potassium (K) are classified as macroelements, and zinc (Zn), manganese (Mn), molybdenum (Mo), and copper (Cu) are classified as microelements.

[0058] According to a first variant of the composition of the invention, the corn chelate(s) take / com take a single mineral nutrient chosen from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper, preferably consisting of zinc, magnesium, calcium and copper.

[0059] According to a second variant of the composition of the invention, the chelate(s) contains several mineral nutrients selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper, preferably the chelate(s) comprises 2, 3, 4 or 5 mineral nutrients selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper, preferably iron, zinc, manganese and molybdenum.

[0060] Preferably, the chelate(s) comprises / include iron, zinc, manganese and / or molybdenum.

[0061] According to another embodiment of the invention, the chelate(s) further comprise at least one anion selected from borate, silicate, phosphate, nitrate.

[0062] According to a first variant of this mode, the corn chelate(s) take / com molybdenum and a borate.

[0063] According to a second variant of this mode, the corn chelate(s) take / com iron, zinc, manganese, molybdenum and a borate.

[0064] Advantageously, the quantity of total amino acids in the composition of chelates according to the invention ranges from 5% to 60%, preferably from 10% to 35%, and preferably from 20% to 30%, by weight relative to the total weight of the composition.

[0065] By "total amino acids of the chelate composition" we mean free amino acids and bound amino acids, these free and bound amino acids being in chelated or non-chelated form.

[0066] Advantageously, the total amount of mineral nutrients in the composition of chelates according to the invention ranges from 0.1% to 15%, preferably from 0.2% to 10%, and preferably from 0.5% to 5% by weight relative to the total weight of the composition.

[0067] It has been observed that the composition of chelates according to the present invention allows very good absorption of amino acids on the one hand and mineral nutrients on the other, thus allowing a reduction of inputs to improve plant growth and productivity.

[0068] According to a first particular embodiment, the chelate composition according to the present invention comprises the particular hydrolysate and zinc.

[0069] According to a second particular embodiment, the chelate composition according to the present invention comprises the particular hydrolysate and calcium.

[0070] According to a third particular embodiment, the chelate composition according to the present invention comprises the particular hydrolysate and magnesium.

[0071] According to a fourth particular embodiment, the chelate composition according to the present invention comprises the particular hydrolysate and copper.

[0072] The chelate composition according to the invention can be used with other plant protection products and / or fertilizers applied in solution to the soil and plants; in fact, they allow the end user to avoid adding additional passes of agricultural machinery on the fields.

[0073] Hydrolysate preparation process

[0074] The hydrolysate used according to the invention is a chemical hydrolysate, as it is obtained by carrying out at least one acidic chemical hydrolysis step. Thus, the keratin hydrolysate used according to the invention is prepared from animal keratin material, preferably poultry, according to a preparation process comprising at least one acid hydrolysis step using a strong acid selected from hydrochloric, phosphoric, and sulfuric acids, preferably hydrochloric acid.

[0075] Advantageously, the hydrolysate used according to the invention is obtained by a preparation process in which the keratinous material is preferably poultry keratinous material, comprising at least the following steps, in this order: - subject the keratin material to at least one acid hydrolysis under conditions suitable for obtaining a hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remainder of the amino acids in the hydrolysate being in the form of peptides having a molecular mass less than or equal to 800 Daltons.

[0076] Preferably, tyrosine and cystine are extracted from said hydrolysate, preferably this extraction is carried out by precipitation using a mineral base.

[0077] The hydrolysate used according to the invention is obtained from natural keratinous materials, advantageously from poultry feathers. Examples of poultry include hens, chickens, turkeys, ducks, geese, etc.

[0078] In particular, the hydrolysate used according to the invention is not obtained from human keratin such as hair.

[0079] The process for preparing the keratin hydrolysate used according to the invention implements at least one hydrolysis using an acid under conditions suitable for obtaining a hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remainder of the amino acids in the hydrolysate being in the form of peptides having a molecular mass less than or equal to 800 Daltons.

[0080] Keratin hydrolysis is carried out using an acid, preferably a strong acid chosen from hydrochloric, phosphoric, and sulfuric acids, preferably hydrochloric acid. Preferably, the strong acid is used at a concentration of 10 to 30%, preferably 15 to 25%.

[0081] Hydrolysis is generally carried out over a period of 1 to 8 hours, preferably 6 to 7 hours, at a temperature of 100 to 115°C, preferably 105 to 115°C. Hydrolysis can be carried out in several stages, for example 2, 3 or 4 stages.

[0082] According to one particular variant, hydrolysis is carried out in two stages: - a first hydrolysis carried out at a temperature ranging from 60 to 80°C for a period of 4 to 5 hours then - a second hydrolysis carried out at a temperature ranging from 100 to 115°C for a period of 5 to 7 hours, the two hydrolyses being able to be carried out without an intermediate pause stage or by carrying out an intermediate pause stage of between 1 hour and 7 days.

[0083] More specifically, the first hydrolysis is carried out at 72°C for 4.5 hours and the second hydrolysis is carried out at 107°C for 6 hours, with an intermediate break of 24 to 80 hours between the two hydrolyses.

[0084] Hydrolysis, carried out in one or more steps, is advantageously followed by at least one step of extraction of cystine and tyrosine.

[0085] The extraction of cystine and tyrosine is carried out using a base, preferably sodium hydroxide, potassium hydroxide, or, more preferably, sodium hydroxide. Adding a base to the hydrolysate causes the less soluble amino acids (primarily cystine and tyrosine) to precipitate, making them separable from the liquid phase by appropriate techniques such as filtration or dewatering.

[0086] The hydrolysis and extraction steps of cystine and tyrosine can be followed by optional purification steps of the resulting hydrolysate.

[0087] The invention further relates to a method of preparing the hydrolysate in which tyrosine and cystine are extracted from said hydrolysate and the liquid phase obtained after the extraction of cystine and tyrosine is desalted.

[0088] In particular, the liquid phase obtained after the extraction of cystine and tyrosine can be desalinated to extract the salts formed by the action of the base on the acid, and thus obtain a desalinated liquid phase.

[0089] The hydrolysis, cystine and tyrosine extraction, and desalination steps can be followed by optional concentration and drying steps, for example by spray drying.

[0090] The desalination, concentration and drying stages are classic stages whose implementation falls within the skills of a person skilled in the art.

[0091] The step of extracting cystine and tyrosine can be followed by an optional step of recovering certain amino acids from the precipitate by re-dissolving it in acid, then re-precipitating it with a base, the amino acids to be recovered then being in the liquid phase, which can be added to the liquid phase from the first dewatering.

[0092] Preferably, the hydrolysate used according to the present invention comprises less than 1% by weight of tyrosine relative to the total weight of the hydrolysate, preferably less than 0.5%, even more preferably, the hydrolysate contains no tyrosine, the only traces of tyrosine being due to the limitations of the operating conditions and the equipment used during the extraction step.

[0093] Preferably, the hydrolysate according to the present invention comprises less than 2.5%, preferably less than 1.5% and preferably less than 1% by weight of cystine relative to the total weight of the hydrolysate; even more preferably, the hydrolysate contains no cystine.

[0094] Furthermore, since the hydrolysate according to the invention is not obtained under reducing conditions, it does not include cysteine.

[0095] Method for preparing the chelate composition

[0096] Preferably, the hydrolysate in liquid form obtained after the extraction of cystine and tyrosine, and after desalting and concentration, is mixed with salts of the chosen mineral elements, preferably sulfates in hydrated form, under stirring, in the desired proportions.

[0097] The mixture is prepared at room temperature for a period of 1 to 3 hours.

[0098] It is possible to use the chelate composition as is for the intended applications.

[0099] It is also possible to dilute the product with water to promote the dissolution of mineral salts in the mixture and ensure good homogeneity, or to facilitate its use in agriculture.

[0100] In the case of a suspension, homogeneity can be achieved by grinding in the liquid phase. The stability of the suspension (absence of settling over time) can be achieved by the possible addition of additives known to those skilled in the art (bentonite, attapulgite, for example).

[0101] It is also possible to dry the chelate composition in solution form by spray drying, in order to obtain the product in powder form.

[0102] Uses

[0103] The composition according to the present invention is advantageously used in agriculture, preferably on plants chosen from among field crops, vines, arboriculture, market gardening, medicinal and aromatic plants, ornamental crops.

[0104] Preferably, the chelating composition according to the invention is used in the form of an aqueous solution comprising 45 to 60% by weight of keratin hydrolysate in solid form relative to the total weight of said composition. The aqueous composition may serve as a carrier for other active ingredients and be diluted accordingly.

[0105] The composition according to the present invention can also be used with at least one agent selected from plant protection products, biocontrol agents, plant biostimulants, microorganism-based products, in particular as a coating.

[0106] The following examples are intended to illustrate the invention without limiting its scope.

[0107] Examples

[0108] Example 1 - Keratin hydrolysate

[0109] Preparation of the hydrolysate

[0110] Hydrolysis

[0111] In a 55,000-liter reactor / hydrolyzer, 9,000 kg of poultry feathers containing 50% dry matter are introduced. Chemical hydrolysis is carried out by adding 18,000 liters of hydrochloric acid (23%); the hydrolysis is performed at 72°C for 4.5 hours.

[0112] The resulting product is stored for 48 hours, allowing its temperature to naturally reach room temperature. Then, a second chemical hydrolysis is carried out by heating it to 107°C for 6 hours without the addition of acid.

[0113] The hydrolysate obtained comprises at least 88% by weight of free amino acids, the remainder of the amino acids in the hydrolysate being in the form of small peptides with a molecular mass less than or equal to 800 Daltons.

[0114] Purification

[0115] The hydrolysate is then allowed to settle to remove the oil from the keratinous material that floats on the surface of the aqueous phase. The excess hydrochloric acid introduced during the hydrolysis step is removed by distillation. 8000 kg of concentrate are recovered. Then, 4500 kg of water are added to obtain 12500 kg of diluted concentrate.

[0116] pH adjustment

[0117] 30.5% sodium hydroxide is added to the hydrolysate to adjust the pH to a value between 4 and 5. Upon addition of sodium hydroxide, the less soluble amino acids, particularly cystine, tyrosine, leucine, and isoleucine, precipitate at least partially. The other amino acids remain completely in solution in the liquid phase.

[0118] Spin drying

[0119] The suspension is then placed in a centrifuge to separate the precipitate (2000 kg) and recover the liquid phase (17000 kg) in a tank.

[0120] Recovery of certain amino acids from the precipitate

[0121] The precipitate (2000 kg) is redissolved in approximately 4% hydrochloric acid (7000 kg), decolorized by passing over activated carbon, and then the solution is neutralized by adding 30% sodium hydroxide (1250 kg). A new precipitate forms, which is separated by dewatering: 650 kg of precipitate and 8750 kg of liquid phase are obtained.

[0122] Liquid phase mixing and desalination

[0123] The liquid phases from the first spin-drying (17000 kg) and the second spin-drying (8750 kg) are combined and desalinated together by electrodialysis to give approximately 17500 kg of desalinated liquid phase.

[0124] Concentration and / or drying

[0125] The liquid phase is concentrated by evaporation of water to reach 55% dry matter (hydrolysate in liquid form);

[0126] Table 1 shows the contents and weight fractions of each of the amino acids in the hydrolysate in powder form.

[0127] [Table 1] The free amino acid content is 93.1% by weight relative to the total amino acid content (free and bound). This content was measured using the method described in Regulation (EC) No 152 / 2009 of 27 January 2009, in particular paragraph 5.3 on page L54 / 27 describes the determination of total amino acids and paragraph 5.2 on page L54 / 27 describes the method for determining free amino acids.

[0128] The molecular mass distribution of the hydrolysate was determined by size-exclusion chromatography according to the method described in the article "Size-exclusion HPLC as a sensitive and calibrationless method for complex peptide mixtures quantification" A. Bodin et al., Journal of Chromatography B, 1005 (2015) 1-9. This method showed that 100% of the protein fraction—including free amino acids and di-, tri-, and tetrapeptides—is less than 520 Daltons. This analysis also showed that the hydrolysate does not contain any peptides with a molecular mass greater than 800 Daltons.

[0129] In the following examples, the hydrolysate used is the hydrolysate according to example 1, in liquid form, it corresponds to a dry matter content of 55% and a nitrogen content of 7.1%.

[0130] In the following examples, the statistical differences between the values ​​were determined by the ANOVA method.

[0131] Application rates were sometimes expressed per hectare (ha), i.e., per 10,000 m³ 2

[0132] Example 2 - Preparation of chelate compositions

[0133] Example 2.1 Preparation of the chelate composition “keratin hydrolysate- Zn »

[0134] In a 5-liter reactor, 1734 grams of hydrolysate (as described in Example 1) in concentrated liquid form, 660 g of zinc sulfate heptahydrate, and 600 grams of water are introduced. The mixture is stirred for one hour at room temperature. The reaction medium is a viscous, opaque brown solution.

[0135] The formulation, i.e., the resulting chelate composition, comprises 29.8% total amino acids, of which 27.1% are free amino acids, and 5.00% zinc. The density of this formulation is 1.305.

[0136] Example 2.2 Preparation of the "keratin hydrolysate-nutrient" chelate composition

[0137] In a 5-liter reactor, 1783 g of hydrolysate as described in Example 1 (in concentrated liquid form), 283 g of iron(II) sulfate heptahydrate, 125 g of zinc sulfate heptahydrate, 87 g of manganese(II) sulfate monohydrate, 96 g of magnesium sulfate heptahydrate, 282 g of monoethanolamine borate solution (comprising, by weight, 20% monoethanolamine, 57.5% boric acid, and 22.5% water), 2.6 g of anhydrous sodium molybdate(III), and 341 g of water are loaded. The mixture is stirred for one hour at room temperature. The resulting medium is a highly viscous brown liquid.

[0138] The formulation, i.e., the resulting chelate composition, comprises 24.8% total amino acids, of which 22.5% are free amino acids, and the following trace elements: 1.89% iron, 0.94% zinc, 0.94% manganese, 1.03% boron, and 0.04% molybdenum. The density of this formulation is 1.350.

[0139] Example 2.3 Preparation of the chelate composition “keratin hydrolysate- B-Mo”

[0140] In a 5-liter reactor, 1203 g of hydrolysate as described in Example 1 (in concentrated liquid form), 1781 g of monoethanolamine borate solution (comprising, by weight, 20% monoethanolamine, 57.5% boric acid, and 22.5% water), and 16.1 g of anhydrous sodium molybdate are added. The mixture is stirred for one hour at room temperature. The resulting medium is a viscous brown liquid.

[0141] The formulation, i.e., the resulting chelate composition, comprises 19.8% total amino acids, of which 18.0% are free amino acids, and the following trace elements: 5.00% boron and 0.20% molybdenum. The density of this formulation is 1.243.

[0142] Example 2.4 Preparation of the chelate composition “keratin-Mg hydrolysate”

[0143] In a 5 L reactor, 1225 g of hydrolysate (as per Example 1) in concentrated liquid form, 300 g of water, and 830 g of magnesium sulfate heptahydrate are loaded. The mixture is stirred for one hour at room temperature. The resulting medium is a thick, brown solution with a slight precipitate.

[0144] The formulation, i.e. the composition of chelates obtained, comprises 25.3% total amino acids, of which 23.0% are free amino acids, and 3.5% magnesium. The density of this formulation is 1.31.

[0145] Example 2.5 Preparation of the "keratin-Cu hydrolysate" chelate composition

[0146] In a 5 L reactor, 3300 g of hydrolysate (as described in Example 1) in concentrated liquid form, 1500 g of water, and 688 g of copper(II) sulfate pentahydrate are added. The mixture is stirred for one hour at room temperature. The resulting solution is fairly fluid, brown with bluish reflections.

[0147] The formulation, i.e., the resulting chelate composition, comprises 29.8% total amino acids, of which 27.1% are free amino acids, and 3.20% copper. The density of this formulation is 1.305.

[0148] Example 3 - Application to plants

[0149] Example 3.1 Application of the "keratin-Zn hydrolysate" composition

[0150] Example 3.1.1 On flax

[0151] Ideo variety flax seeds were placed in seed furrows using a seed drill – to ensure uniform sowing – at a density of 2320 g of flax seeds per 1 m². 2

[0152] Then the chelate composition prepared in Example 2.1 was applied as a foliar spray at BBCH stage 15. The growth stage of the flax plants was determined using the BBCH scale for flax fiber. According to this scale, codes 10 to 19 correspond to leaf development, in particular code 15 corresponds to the presence of 5 fully extended leaves.

[0153] The chelate composition was applied at a dose corresponding to 5.5 liters of the chelate composition in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 planted area.

[0154] As a control, flax seeds of the same variety were planted at the same density of 2320 g flax seeds per 1 m² 2 .

[0155] Another control was used: keratin hydrolysate according to Example 1 at a dose corresponding to 3 liters of hydrolysate in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 of planted area and sprayed on the leaves at BBCH15 stage 1. This dose corresponds to the same quantity of keratin hydrolysate as that present in 5.5 L of keratin-Zn hydrolysate (composition of example 2.1).

[0156] Table 2 shows the levels of macro-elements (NH4 + and Ca) in ppm measured in flax sap at BBCH stage 51. The growth stage of flax plants was determined using the BBCH scale for fiber flax. According to this scale, the codes 50 to 59 correspond to the development of flower buds, in particular the codes 51 corresponds to the presence of 10% of visible flower buds.

[0157] [Table 2]

[0158] Table 3 shows the micronutrient (B and Zn) content in ppm measured in flax sap at BBCH stage 51. The growth stage of the flax plants was determined using the BBCH scale for fiber flax. According to this scale, codes 50 to 59 correspond to the development of flower buds, with code 51 specifically indicating the presence of 10% of visible flower buds.

[0159] [Table 3] [C160] The use of the chelate composition according to the invention made it possible to increase the content of ammonium, calcium, boron and zinc in the sap at BBCH stage 51.

[0161] This increase in micro- and macro-element content at this stage reflects better nutrient assimilation by the plant when the chelate composition according to the invention is used, in particular better assimilation of nutrients not present in the composition (according to example 2.1) applied.

[0162] Example 3.1.2 On maize

[0163] Futurixx variety corn seeds were sown in pots at a rate of 3 seeds per pot. The pots have a capacity of 4 liters and the growing medium used consists of 50% perlite and 50% vermiculite.

[0164] The different modalities, applied as a foliar spray at BBCH stage 16, are detailed in Table 4 below. The growth stage of the maize plants was determined using the BBCH maize growth chart. According to this chart, codes 10 to 19 correspond to the development of the leaves, in particular the codes 16 corresponds to the presence of 6 spread leaves.

[0165] [Table 4] [C166] The chelate composition according to Example 2.1 was applied at a dose corresponding to 5.5 liters of said composition in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 planted area (modality 4).

[0167] As a control, corn seeds of the same variety were planted at the same density of 3 seeds per pot and watered only with water (modality 1).

[0168] Another control was used: keratin hydrolysate alone at a dose corresponding to 3 liters of hydrolysate in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2of planted area and sprayed on the leaves at BBCH16 stage 1 (modality 2). This dose corresponds to the same quantity of keratin hydrolysate as that present in 5.5 L of keratin-Zn hydrolysate (composition of example 2.1).

[0169] Another control was used: zinc alone at a dose corresponding to 440 g of solid zinc (in a slurry of 200 L of water) per 10,000 m 2 of planted area and sprayed on the leaves at BBCH16 stage 1 (modality 3). This dose corresponds to 50% of the zinc content in 5.5 L of hydrolysate of Keratin-Zinc. This dose corresponds to 22% more by weight compared to the amount of zinc present in 5.5 L of the keratin-Zn hydrolysate composition (composition of example 2.1).

[0170] Another control was used: zinc-EDTA at a dose corresponding to 440 g of zinc in solid form (in a slurry of 200 L of water) per 10,000 m³ 2of planted area and sprayed on the leaves at BBCH16 stage 1 (treatment 5). This treatment allows for comparison of the effectiveness of a chemical chelate composition with the chelate composition according to the invention. This dose corresponds to 22% more by weight compared to the amount of zinc present in 5.5 L of keratin-Zn hydrolysate (composition of Example 2.1).

[0171] Table 5 below represents the zinc content in 10' 6 g / plant measured in corn leaves 24 h after application of products.

[0172] [Table 5] C173] The use of the chelate composition according to the invention (modality 4) makes it possible to increase the zinc content in the leaves at BBCH stage 16.

[0174] This increase in Zn content at this stage reflects better nutrient assimilation by the plant when zinc is chelated with keratin hydrolysate.

[0175] The chelate composition according to the invention is more efficient than a chemical chelate, (+35% compared to modality 5) and than zinc alone (+41% compared to modality 3).

[0176] This result is statistically significant (p<0.10).

[0177] Example 3.2 Application of the "keratin hydrolysate-nutrients" composition

[0178] Example 3.2.1 On maize

[0179] Futurixx variety corn seeds were sown in pots at a rate of 3 seeds per pot. The pots have a capacity of 4 liters and the growing medium used consists of 50% perlite and 50% vermiculite.

[0180] The different foliar spraying methods applied at BBCH stage 16 are detailed in Table 6 below. The growth stage of the maize plants was determined using the BBCH maize growth chart. According to this chart, codes 10 to 19 correspond to leaf development, with code 16 specifically indicating the presence of 6 fully unfurled leaves.

[0181] [Table 6]

[0182] The chelate composition according to example 2.2 was applied at a dose corresponding to 1.5 liters of the composition in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 planted area (modality 4).

[0183] As a control, corn seeds of the same variety were planted at the same density of 3 seeds per pot and watered only with water (modality 1).

[0184] Another control was used: keratin hydrolysate alone at a dose corresponding to 3 liters of hydrolysate in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 of planted area and sprayed on the leaves at BBCH16 stage 1 (modality 2). This dose corresponds to the same quantity of keratin hydrolysate as that present in 1.5 L of keratin-Zn hydrolysate (composition of example 2.2).

[0185] Another control was used: nutrients alone at a dose corresponding to 1.5 L / ha in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 of planted area and sprayed on the leaves at BBCH16 stage (modality 3). This dose corresponds to the same quantity of nutrients as that present in 1.5 L of keratin-nutrient hydrolysate (composition of example 2.2).

[0186] Another control was used: EDTA nutrient at a dose corresponding to 1.5 L / ha in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 of planted area and sprayed on the leaves at BBCH16 stage (modality 5). This modality allows comparison of the effectiveness of a chemical chelate composition with the chelate composition according to the invention.

[0187] Table 7 represents the zinc and manganese (micronutrient) content in pg / plant measured in corn leaves 24 h after application of the products.

[0188] [Table 7] Tl

[0189] The use of the chelate composition according to the invention (modality 4) makes it possible to increase the zinc and manganese content in maize leaves at BBCH stage 16.

[0190] This increase in micronutrient content at this stage reflects better nutrient assimilation by the plant when zinc is chelated with keratin hydrolysate.

[0191] With the same quantity of nutrients, the composition of chelates is more efficient than a chemical chelate (+21% for Zn and +39% for Mn, see modality 5) and than nutrients alone (+5% for Zn and +28% for Mn; see modality 3).

[0192] This result is statistically significant (p<0.10).

[0193] Example 3.2.2 On carrots

[0194] Nérac variety carrot seeds were placed in seed furrows using a seed drill—to ensure uniform sowing—at a density of 71.4 g carrot seeds per 1 m². 2

[0195] Then, the chelate composition according to example 2.2 was applied as a foliar spray at BBCH stage 16, 10 days after the first application, and again at BBCH stage 42. The growth stage of the carrots was determined using the BBCH scale for root or tuber species. According to this scale, codes 10 to 19 correspond to leaf development; in particular, code 16 corresponds to the presence of 6 fully unfurled leaves. According to this scale, codes 40 to 49 correspond to to the development of vegetative organs for harvest, in particular codes 42 corresponds to 20% of the final size of the carrot root.

[0196] The chelate composition according to example 2.2 was applied at a dose corresponding to 1 liter of said composition in liquid form (in a slurry of 400 L of water) per 10,000 m 2 planted area (modality 3).

[0197] As a control, carrot seeds of the same variety were planted at the same density of 71.4 g carrot seeds per 1 m² 2 and watered only with water (modality 1).

[0198] Another control was used: keratin hydrolysate alone at a dose corresponding to 1 liter of hydrolysate in liquid form (in a slurry of 400 L of water) per 10,000 m 2 of planted area and sprayed on the leaves (modality 2). This dose corresponds to 2 times the quantity of keratin hydrolysate that is present in 1 L of the keratin-nutrient composition (composition of example 2.2).

[0199] Another control was used: nutrients alone at a dose corresponding to 1 L / ha in liquid form (in a slurry of 400 L of water) per 10,000 m³ 2of planted area and sprayed on the leaves (modality 4). This dose corresponds to the same quantity of nutrients present in 1 L of the composition according to example 2.2.

[0200] Table 8 represents the root and leaf biomass 3 months after carrot sowing.

[0201] [Table 8] to increase root and leaf biomass 3 months after sowing.

[0203] The chelate composition according to the invention is more effective than keratin hydrolysate alone and nutrients alone.

[0204] Table 9 shows the average weight in grams of marketable carrots at harvest

[0205] [Table 9] The use of the chelate composition according to the invention significantly increases the average weight of marketable carrots at harvest by 29% compared to the water control. The chelate composition according to the invention is more effective than keratin hydrolysate alone and trace elements alone.

[0206] Example 3.2.3 On tomatoes

[0207] Microtom WT tomato seeds were sown in pots, one seed per pot, in a climate chamber. The pots had a capacity of 2 liters, and the growing medium used was a mixture of Hortifibre, clay, brown peat, and blonde peat.

[0208] Then the chelate composition according to example 2.2 was applied as a foliar spray 3, 5 and 10 weeks after sowing. The trial lasted 19 weeks.

[0209] The chelated composition was applied at a dose corresponding to 1.5 liters of said composition in liquid form (in a slurry of 200 L of water) per 10,000 m 2 planted area.

[0210] As a control, tomato seeds of the same variety were planted at the same density of one seed per pot and watered only with water (modality 1).

[0211] Another control was used: keratin hydrolysate alone at a dose corresponding to 3 liters of hydrolysate in liquid form (in a slurry of 400 L of water) per 10,000 m 2 of planted area and sprayed onto the leaves. This dose corresponds to twice the amount of keratin hydrolysate present in 1 L of the composition according to example 2.2

[0212] Table 10 represents the root and leaf biomass of tomatoes at the end of the trial.

[0213] Table 10]

[0214] The use of the chelate composition according to the invention significantly increases the root and leaf biomass of tomato plants. The chelate composition according to the invention is more effective than the hydrolysate of Keratin alone. It allows for good early development and good vigor of tomato plants.

[0215] Example 3.3 Application of the "keratin-B-Mo hydrolysate" composition

[0216] Example 3.3.1 On rapeseed

[0217] Helypse variety rapeseed seeds were placed in seed furrows using a seed drill – to ensure uniform sowing – at a density of 40 g rapeseed per 1 m². 2

[0218] Then, the chelate composition according to example 2.3 was applied as a foliar spray at BBCH stage 59. The growth stage of the rapeseed plants was determined using the BBCH rapeseed growth chart. According to this chart, codes 50 to 59 correspond to the appearance of inflorescences; in particular, code 59 corresponds to the presence of the first petals, but the flowers are still closed.

[0219] The chelated composition was applied at a dose corresponding to 1.5 liters of said composition in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 planted area (modality 3).

[0220] As a control, rapeseed seeds of the same variety were planted at the same density of 40 g rapeseed per 1 m² 2 and watered only with water (modality 1).

[0221] Another control was used: keratin hydrolysate alone at a dose corresponding to 1.5 liters of hydrolysate in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 of planted area and sprayed on leaves at BBCH59 stage 1 (modality 2).

[0222] Another control was used: a mixture of boron and molybdenum alone at a dose corresponding to 1.5 L / ha in liquid form (in a slurry of 400 L of water) per 10,000 m³ 2 of planted area and sprayed on the leaves (modality 4). This dose corresponds to the quantity of trace element present in 1.5 L of the composition according to example 3.2. Table 11 shows the boron and molybdenum content in ppm measured in rapeseed leaves 48 h after application of the products.

[0223] [Table 11]

[0224] The use of the chelate composition according to the invention makes it possible to increase the boron and molybdenum content in rapeseed leaves 48 h after application of the products at BBCH stage 59.

[0225] This increase in micronutrient content at this stage reflects better nutrient uptake by the plant when boron and molybdenum are chelated with keratin hydrolysate. Applying boron and molybdenum at BBCH stage 59 ensures successful rapeseed flowering.

[0226] Example 3.4 Application of the "keratin-Mg hydrolysate" composition

[0227] Example 3.4.1 On rice

[0228] Rice seeds of the Samagrin variety were placed in seed furrows using a seed drill - in order to ensure homogeneous sowing.

[0229] Then, the chelate composition according to example 2.4 was applied as a foliar spray twice: at BBCH stages 41 and 61. The rice growth stage was determined using the BBCH scale for cereals. According to this scale, codes 40 to 49 correspond to ear swelling; in particular, code 41 corresponds to the beginning of swelling, i.e., the elongation of the leaf sheath of the flag leaf. According to this scale, codes 60 to 69 correspond to the flowering, in particular code 61 corresponds to the beginning of flowering, the first anthers are then visible.

[0230] The chelate composition according to example 2.4 was applied at a dose corresponding to 4 liters of said composition in liquid form (in a slurry of 200 L of water) per 10,000 m³ 2 planted area.

[0231] As a control, rice seeds of the same variety were planted at the same density.

[0232] Table 12 shows the number of grains per ear and the yield in kg / ha compared to the untreated control.

[0233] [Table 12]

[0234] The use of the chelate according to the invention makes it possible to have an impact on the final yield of rice compared to an untreated control: the number of grains per ear is increased by 22%.

[0235] Example 3.5 Application of the "keratin-Cu hydrolysate" composition

[0236] Example 3.5.1 On the vine

[0237] The trial was carried out on a Cabernet Franc vine.

[0238] The chelate composition according to Example 2.5 was applied as a foliar spray at growth stages BBCH 11, BBCH 19, BBCH 53, BBCH 57, BBCH 60, BBCH 69, BBCH 71, BBCH 75, BBCH 77, and BBCH 79. The growth stage of the grapevine plants was determined using the BBCH Grapevine Growth Chart. According to this chart, codes 10 to 19 correspond to the first unfurled leaves; specifically, code 11 corresponds to the presence of the first leaf, and code 19 corresponds to nine or more leaves. According to this chart, codes 50 to 59 correspond to the appearance of the Inflorescences, specifically code 53 corresponds to the presence of the first cluster, and code 57 corresponds to the point at which the clusters are well-developed and the flowers separate. According to this scale, codes 60 to 69 correspond to flowering; specifically, code 60 corresponds to the presence of the first flower caps separating from the receptacle, and code 69 corresponds to the end of flowering. According to this scale, codes 70 to 79 correspond to fruit set; specifically, code 71 corresponds to the beginning of fruit development, code 75 to berries the size of peas, code 77 to the cluster closure stage, and code 79 to the complete closure of the clusters, when the fruits have finished enlarging.

[0239] Table 13 below describes all the methods used during this experiment.

[0240] Table 13

[0241] The composition according to the invention (example 2.5) was applied at a dose corresponding to 1.5 liters of copper chelate in liquid form (in a slurry of 200 L of water) per 10000 m 2 of planted area. The quantity of copper applied was reduced by 55% by weight compared to the crop's need when copper alone, in conventional form, is applied (modality 5).

[0242] As a control, the vine stocks were watered with water only (modality 1).

[0243] Another control was used: full-dose copper (treatment 2), designed to allow the winegrower complete protection of their vines against downy mildew. In this treatment, copper is applied in the classic form of "Bordeaux mixture RSR" (Bordeaux mixture in English): that is, containing 20% ​​copper sulfate by weight.

[0244] Another control was used, copper in classical form in a reduced dose, i.e. -70% copper compared to the full dose (modality 3).

[0245] Another control was used, copper in reduced dose and was combined extemporaneously with keratin hydrolysate alone (modality 4).

[0246] Table 14 shows the percentage of downy mildew severity on grape bunches. Severity represents the percentage of berries showing symptoms of downy mildew on a bunch.

[0247] [Table 14]

[0248] The use of the composition according to the invention makes it possible to significantly reduce, by 55%, the doses of copper while maintaining the effectiveness of a full dose of copper in conventional form.

Claims

Demands

1. [Composition of at least one amino acid chelate of a hydrolysate with at least one mineral nutrient, wherein the hydrolysate is a keratin hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids in the hydrolysate, the remainder of the amino acids in the hydrolysate being in the form of peptides having a molecular mass less than or equal to 800 Daltons, said hydrolysate comprising from 2 to 12% by weight of peptides of 2, 3, 4 amino acids having a molecular mass less than or equal to 800 Daltons by weight relative to the total weight of the hydrolysate, said hydrolysate having the following composition in total amino acids: an aspartic acid content of 5 to 8% by weight; a threonine content of 3 to 6% by weight; a serine content ranging from 9 to 14% by weight; a glutamic acid content ranging from 8 to 13% by weight; a glycine content ranging from 6 to 9% by weight;an alanine content ranging from 4 to 6% by weight; a valine content ranging from 6 to 10% by weight; a methionine content ranging from 0.1 to 0.6% by weight; an isoleucine content ranging from 4 to 6% by weight; a leucine content ranging from 6 to 9% by weight; a phenylalanine content ranging from 2 to 5% by weight; a lysine content ranging from 1 to 3% by weight; a histidine content ranging from 0.4 to 1% by weight; an arginine content ranging from 5.5 to 6.5% by weight; a proline content ranging from 8.5 to 11% by weight, a tryptophan content of less than 0.1%, relative to the total weight of total amino acids in the hydrolysate and the mineral nutrient being chosen from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper.;

2. Composition according to claim 1 wherein the hydrolysate has the following total amino acid composition: an aspartic acid content of 6 to 7% by weight; a threonine content of 4 to 5% by weight; a serine content of 10 to 12% by weight; a glutamic acid content of 9 to 11% by weight; a glycine content of 6.5 to 8% by weight; an alanine content of 4 to 5% by weight; a valine content of 6.5 to 8% by weight; an isoleucine content of 4 to 5% by weight; a content of leucine ranging from 7 to 8% by weight; a tryptophan content of 0% relative to the total weight of total amino acids in the hydrolysate.

3. Composition according to any one of the preceding claims wherein the chelate(s) comprises / comprise a single mineral nutrient selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, potassium, cobalt and copper, preferably consisting of zinc, magnesium, calcium and copper.

4. Composition according to any one of claims 1 or 2 wherein the chelate(s) comprises 2, 3, 4 or 5 mineral nutrients selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, potassium, cobalt and copper, preferably the chelate comprises iron, zinc, manganese and molybdenum.

5. A composition according to any one of the preceding claims, wherein the chelate(s) further comprises at least one anion selected from borate, silicate, phosphate, and nitrate.

6. A composition according to any one of the preceding claims, wherein the hydrolysate comprises the following free amino acids: at least 95% aspartic acid in free form by weight relative to the total weight of aspartic acid in the hydrolysate; at least 95% threonine in free form by weight relative to the total weight of threonine in the hydrolysate; at least 95% serine in free form by weight relative to the total weight of serine in the hydrolysate; at least 93% glutamic acid in free form by weight relative to the total weight of glutamic acid in the hydrolysate; at least 93% of glycine in free form by weight relative to the total weight of glycine in the hydrolysate;at least 93% of alanine in free form by weight relative to the total weight of alanine in the hydrolysate; at least 95% of methionine in free form by weight relative to the total weight of methionine in the hydrolysate; at least 93% of phenylalanine in free form by weight relative to the total weight of phenylalanine in the hydrolysate; at least 95% of proline in free form by weight relative to the total weight of proline in the hydrolysate.

7. A method for preparing the composition according to any one of claims 1 to 6 comprising at least one step of mixing the hydrolysate defined in any one of claims 1 to 3 with at least one mineral nutrient is selected from the group consisting of iron, zinc, manganese, magnesium, calcium, molybdenum, cobalt and copper, preferably in the form of hydrated sulfate(s), said mixing step being carried out under stirring for a period of 1 hour to 3 hours.

8. A process for preparing the composition according to the preceding claim, wherein the hydrolysate is prepared from an animal keratinous material, preferably poultry, according to a preparation process comprising at least the following steps, in this order: - subject the keratinous material to at least one acid hydrolysis, carried out in two stages: -a first hydrolysis carried out at a temperature ranging from 60 to 80°C for a period of 4 to 5 hours then -a second hydrolysis carried out at a temperature ranging from 100 to 115°C for a period of 5 to 7 hours, the two hydrolyses being able to be carried out without an intermediate pause or with an intermediate pause of between 1 hour and 7 days - extract the tyrosine and cystine from said hydrolysate preferably by means of a base; -desalinate the liquid phase obtained after the extraction of cystine and tyrosine; - concentrate the desalinated liquid phase to obtain an aqueous composition comprising 45 to 60% by weight of keratin hydrolysate in solid form relative to the total weight of said composition.

9. Use of the composition according to any one of claims 1 to 6 or obtained according to claim 7 or 8 in agriculture, preferably as a plant biostimulant.

10. Use of the composition according to the preceding claim as a biostimulant for plants selected from among the plants of large-scale agriculture, vineyards, arboriculture, market gardening, medicinal and aromatic plants, ornamental crops.

11. Use of the composition according to claim 9 or 10 to improve the absorption of mineral nutrients and amino acids by the plant and to reduce the amount of mineral inputs.

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