Magnesium product for controlling abiotic stress in a crop

Abstract

The invention relates to a magnesium product which can be used for controlling solar abiotic stress of plants. The product comprises a mixture of two magnesium agents, including a first magnesium agent with a particle size greater than 10 microns and a second magnesium agent selected from magnesium raw materials with a particle size of less than 10 microns and water-soluble magnesium salts.

Description

Description Title of the invention: Magnesium product for controlling abiotic stress in a crop Technical Field

[0001] The present invention relates to a magnesium composition which can be used as an agrochemical product for the control of abiotic solar stress in plants. Prior art

[0002] Various solutions have been proposed to try to combat sunburn on plants. For example, micronized mineral powders combined with active ingredients such as antioxidants, UV filters, or even microorganisms are formulated into suspensions for foliar application and to form a protective film of particles.

[0003] Micronized mineral powders based on silicates such as kaolin and talc are most commonly used to reduce sunburn by blocking the sun's rays, given their high effectiveness.

[0004] The use of calcium carbonate and magnesium carbonate has also been mentioned in the prior art, but has been relegated to the background due to the lack of effective protection against sunburn.

[0005] These mineral powders do not necessarily have the same mode of action. These solar radiation blocking agents reflect only a portion of the incident sunlight and provide protection for only a portion of the light spectrum, i.e., against UV radiation, visible radiation, and / or infrared radiation. For example, certain forms of silicates have been cited as white UV-reflecting pigments. Powders with small particle sizes are generally taught to be the most active.

[0006] In application US20160037772 it was suggested to improve the protection of plants against abiotic stress by combining a mineral sunscreen compound with 9-oxo-nonanoic acid or arachidonic acid. The mineral compound identified as the most effective active component in the fight against ultraviolet radiation was a kaolin or calcium carbonate with a particle size of the order of 0.5 to 3 microns.

[0007] In application WO2009064450 again, the formulation of micronized calcium carbonate in the form of an aqueous suspension was proposed as a sunscreen product.

[0008] White pigments such as titanium dioxide with a particle size of 0.5-2 microns have also been integrated into the polymer matrix of a crop protection net to improve the visible transmittance and increase the net's UV absorption (US application 20210144932). However, the manufacture of a net is expensive and its installation on crops by the farmer can be tricky.

[0009] It is therefore desirable to reduce the production cost of sun protection solutions and make them easier to apply to crops in order to make farms more profitable.

[0010] There is also a continuing need for a micronized mineral product with improved plant protection activity against abiotic stress. Indeed, the level of crop protection can be optimized to reduce certain constraints associated with current solutions, particularly by reducing the doses of mineral matter and reducing crop bleaching. It would therefore be desirable to reduce the doses of mineral matter required to achieve effective protection, and consequently to reduce bleaching of crops to which the agrochemical product is applied while increasing crop productivity. Statement of the invention

[0011] The present invention specifically addresses these needs by providing a magnesium agrochemical product in powder form that can be advantageously applied as a film of particles to plant tissues to control the solar abiotic stress they experience.

[0012] A first subject of the invention thus relates to an agrochemical product in the form of a powder of particles comprising a mixture of at least one first magnesium agent and at least one second magnesium agent for controlling the abiotic solar stress suffered by a crop, said mixture being able to be synergistic.

[0013] The inventors surprisingly found that the choice of mineral proves to be decisive in effectively combating the blight phenomenon. Indeed, the level of crop protection can be optimized by increasing the effectiveness of the mineral product.

[0014] The magnesium mineral material of the product of the invention advantageously makes it possible to exercise at least one activity chosen from increasing the level of sun protection of crops, reducing the dose of mineral particles provided to crops with equivalent sun protection, limiting the bleaching of crops, improving photosynthetic activity, and increasing crop productivity. The product of the invention notably allows an increase in the rate of foliar emission thanks to the reduction in leaf coverage compared to the mineral powders of the prior art. Indeed, the higher the minimum dose of sun protection agent necessary to protect the leaves, the higher the quantity of powder covering the surface of the leaves, which has the effect of reducing the photosynthetic activity of the plant.

[0015] In a particular embodiment, the magnesium mineral material of the invention allows the reduction of bleaching of crops with equivalent sun protection and / or the increase in crop productivity.

[0016] The magnesium mineral material of the product of the invention, by its physicochemical characteristics, has a specific behavior in the face of the phenomenon of burning, by a physical interaction with solar radiation including reflection, diffusion, or even absorption of the rays, but also by biological interaction with the plant by supporting the processes of treatment and management of damage linked to these same radiations.

[0017] By taking into account the role that mineral matter can play both physically and biologically, solar protection of crops can thus be optimized to maintain or even increase crop productivity in a context of normal radiation exposure (<1500 kWh / m 2 / year) to high (>1500 kWh / m 2 / year).

[0018] The present invention has the effect of limiting the damage induced by the solar radiation spectrum on the plant, by acting on at least one of the following effects: i) the reduction of water stress by lowering the surface temperature, thus limiting the use of the evapotranspiration mechanism, a natural regulator of the internal temperature of the plant; ii) the optimization of the sizes produced, the increase in SSC (Solid Soluble Content) rates, by maintaining photosynthesis later in conditions of intense radiation; iii) the optimization of the coloring of the crops by protecting the photosynthetic pigments, by limiting the metabolic impact of the oxidative species (ROS) which attack the latter.

[0019] The contribution of the invention in the fight against these damages helps to maintain, or even increase, the productivity of crops.

[0020] The invention also relates to the use of at least one first magnesium agent and at least one second magnesium agent as described above for controlling solar abiotic stress suffered by plant tissues, preferably chlorophyllous plant tissues.

[0021] Finally, a final object of the invention relates to an agricultural method for applying to a crop an agrochemical product in accordance with the preceding description. Brief description of the drawings Figure 1 represents the particle size distribution of a magnesium agrochemical product according to the invention. Figure 2 represents the UV-Visible spectral signature of a magnesium agrochemical product according to the invention. Figure 3 represents the evolution of the number of leaves per plant under conditions of artificially generated solar abiotic stress following an application of two magnesium agrochemical products according to the invention in comparison with a product according to the prior art. Figure 4 represents the average percentage of watermelon epidermis affected by sunburn on a control sample of untreated watermelons, on a sample of culture treated with a product of the prior art and on a sample of culture treated with a magnesium agrochemical product according to the invention. Figure 5 shows the mass of three watermelon harvests, the first being untreated, the second being treated with a prior art product and the third with a magnesium agrochemical product according to the invention. Figure 6 shows the distribution by category of watermelons at harvest on an untreated harvest, a harvest treated with a product of the prior art and a harvest treated with a magnesium agrochemical product according to the invention. Description of the embodiments

[0022] A first subject of the invention thus relates to an agrochemical product in the form of a powder of particles comprising a mixture of at least one first magnesium agent and at least one second magnesium agent for controlling the abiotic solar stress suffered by a crop, - the first magnesium agent having a particle size ranging from 10 microns to 150 microns, preferably ranging from 10 microns to 110 microns, and being a magnesium material comprising at least one compound chosen from magnesium carbonate (MgCO3), dolomite (CaMg(CO3)2), magnesium oxide (MgO), magnesium silicate (Mg xSiOy, x and y being decimal numbers), magnesium hydroxide (Mg(OH)2), and their hydrates, and - the second magnesium agent, different from the first magnesium agent, being chosen from: a) a water-soluble magnesium agent chosen from magnesium materials comprising at least one compound chosen from magnesium sulfate and its hydrates (MgSO 4.z H2O, z being an integer), magnesium nitrate and its hydrates (Mg(NO3) 2.t H2O, t being an integer), magnesium chloride and its hydrates (MgCI 2.pH2O, p being an integer), and organic magnesium salts chosen from magnesium bisglycinate, magnesium citrate, magnesium aspartate, magnesium lactate, magnesium glycerophosphate, magnesium pidolate and magnesium gluconate, and from b) a magnesium agent whose particle size is between 0.1 and 10 microns and being a magnesium material comprising at least one compound chosen from magnesium carbonate (MgCO3), dolomite (CaMg(CO3)2), magnesium oxide (MgO), magnesium silicate (Mg x SiO y x and y being decimal numbers), magnesium hydroxide (Mg(OH)2), and their hydrates.

[0023] This mixture of magnesium agents may be synergistic. The synergistic function may be measured by any method known to those skilled in the art, in particular by the Colby method. It may also be defined by measuring, under the same conditions, the activity of the first magnesium agent, the activity of the first magnesium agent and the activity of the mixture of the first and second magnesium agents, at equal doses.

[0024] "Magnesium material" means a material comprising more than 50% by mass, or even more than 80% or more than 90% by mass of a magnesium compound. Magnesium material may be a magnesium material obtained by extraction from an ore followed by grinding and micronization.

[0025] The particle size of the first magnesium agent, also called particle size or particle size distribution, ranges from 10 microns to 150 microns. For example, it is located in one of the following ranges: from 10 microns to 140 microns, from 10 microns to 120 microns or from 10 to 110 microns. In a particular embodiment of the invention, it ranges from 10 microns to 120 microns.

[0026] The particle size of the second magnesium agent, which may also be referred to as "particle size" or "particle size distribution", is between 0.1 and 10 microns, when it is chosen from magnesium materials comprising at least one compound chosen from magnesium carbonate, dolomite, magnesium oxide, magnesium silicate, magnesium hydroxide or one of their hydrates.

[0027] In the present application, the expression "ranges from ... to ..." to describe a range of value includes the limits, while the expression "between ... and ...." to describe a range of value which excludes the limits.

[0028] The size of the particles can be determined by mass, number or volume by any method known to those skilled in the art such as sedimentometry or laser diffraction for example, the characteristic size of a particle being for example defined as equal to the diameter of a sphere of the same volume as that of the particle.

[0029] Sedimentometry is based on the evaluation of the settling rate of magnesium-containing particles in water. The method uses the absorption of X-rays by the suspension of particles at a given height and time.

[0030] The relative particle size distribution of the first magnesium agent and the second magnesium agent, also called the particle size distribution of the mixture of the first and second magnesium agents, can be represented in an increasing cumulative mode, by summing the fractions of particles whose size is less than a given value.

[0031] According to a particular embodiment, the particle size distribution of the mixture is such that the first magnesium agent represents between 1 and 99% of the total volume of the mixture, preferably between 60% and 80% of the total volume of the product or mixture, and the second magnesium agent represents between 1 and 99% of the total volume of the product, preferably between 20% and 40% of the total volume of the product or mixture.

[0032] The characteristic diameters of the mixture of the two magnesium agents may be D10, D50 or D90 which correspond respectively to 10%, 50% and 90% of the cumulative frequency in number, mass or volume. In one embodiment of the present invention, the mixture has a particle size defined as the particle size distribution ranging from 0.1 to 150 microns. The mixture may have an average particle diameter D50 of between 5 microns and 40 microns, for example between 10 microns and 20 microns, D50 referring to the median of the particle diameter of the mixture.

[0033] In a particular embodiment, the first magnesium agent is a magnesium material comprising magnesium carbonate, and the second magnesium agent is a magnesium material comprising magnesium carbonate. In this embodiment, the magnesium materials advantageously contain magnesium carbonate in a predominant amount. The magnesium materials advantageously consist essentially of magnesium carbonate.

[0034] In this description, "consisting essentially of" is understood to mean more than 90% by mass, for example more than 95% or more than 98% by mass.

[0035] In another embodiment of the invention, the second magnesium agent is a mixture consisting of a) a water-soluble magnesium agent selected from magnesium sulfate and its hydrates, magnesium nitrate and its hydrates, magnesium chloride and its hydrates, and organic magnesium salts selected from magnesium bisglycinate, magnesium citrate, magnesium aspartate, magnesium lactate, magnesium glycerophosphate, magnesium pidolate and magnesium gluconate, and b) a magnesium agent with a particle size of between 0.1 and 10 microns selected from magnesium carbonate, dolomite, magnesium oxide, magnesium silicate, magnesium hydroxide and their hydrates.

[0036] For example, the second magnesium agent is a mixture of magnesium carbonate with a particle size of 0.1-10 microns and magnesium sulfate.

[0037] The proportion by volume of these two magnesium raw materials may be between 10 / 90 and 90 / 10, be greater than a value chosen from 10 / 90, 20 / 80, 30 / 70, 40 / 60 and 50 / 50, and be less than or equal to a value chosen from 90 / 10, 80 / 20, 70 / 30, 60 / 40 and 50 / 50.

[0038] The whiteness index of the product of the invention may advantageously be greater than 60, greater than 70, or preferably greater than 75, the person skilled in the art having at his disposal several methods for measuring the whiteness index forming part of his general knowledge. For example, the whiteness index of the mixture, measured in the CIE colorimetric system (W CiE ), can be greater than 60, preferably greater than 75.

[0039] In a particular embodiment, the product of the invention is essentially made up of magnesium materials.

[0040] The mixture of magnesium agents contained in the agrochemical product of the invention has a very advantageous reflectance. It can in fact act simultaneously on the reflection, diffusion, and absorption by filtration of all solar radiation including ultraviolet, the visible range, and infrared.

[0041] An ultraviolet range within the meaning of the invention may be that of UVb located between 280 nm and 315 nm. A visible range within the meaning of the invention may be located between 430 nm and 660 nm, or more precisely between 445 nm and 645 nm. Finally, an infrared range may be located in the range from 700 nm to 900 nm.

[0042] Thus, the reflectance of the magnesium mixture can advantageously be greater than 60%, or even 65% for each of the wavelengths of the solar spectrum.

[0043] More specifically, the mixture of magnesium agents in the agrochemical product of the invention has an activity in the UVb range making it possible to limit the production of ROS and damage to DNA. Its reflectance in the UVb range is very advantageously greater than 50%, 55%, 60%, or even 65%.

[0044] In addition, the agrochemical product of the invention can limit the influx of photons onto the photosynthetic pigments of plant tissue that are active at wavelengths chlorophyll activity, particularly chlorophyll a (430 nm - 660 nm) and chlorophyll b (445 nm - 645 nm) which are also called "Photosynthetically Active Radiation" or "PAR" in English. In this area of ​​the spectrum, the magnesium agent mixture can have a reflectance greater than 70% or 75%.

[0045] Finally, the product of the invention can also limit the rise in temperature caused by infrared and the absorption of visible rays which cause the breakdown of plant cells gradually leading to browning and then necrosis. For this purpose, the reflectance in the infrared range can be greater than 60% or 65%.

[0046] The product of the invention is very advantageously characterized by an average reflectance value greater than or equal to 60%, preferably greater than or equal to 65%, more preferably greater than 70%, the average being measured over an entire spectrum ranging from 250 to 900 nm. The reflectance of the product may be greater than or equal to 75% over at least one range of the spectrum.

[0047] The spectral reflectance signature of the agrochemical product of the invention can be measured by any method known to those skilled in the art.

[0048] Unlike prior art mineral sunscreens that act as physical screens by masking the surface of plants, the agrochemical product of the invention has the advantage of providing a source of magnesium that is assimilated by the plant. The supply of nutrient magnesium by the product of the invention makes it possible to support normal metabolic activity in the context of radiation-generated stress, to stabilize the chlorophyll molecule to maintain photosynthesis, to stabilize ATP, to act as an enzymatic cofactor for CO2 fixation, and to limit the accumulation of sugars in photosynthetic organs.

[0049] In conclusion, the combination of magnesium agents of the invention makes it possible to combat the phenomenon of burning by simultaneously exerting a physical action (by reflecting a large part of the solar radiation), and a biological action by supporting the processes of treatment and management of damage linked to these same radiations.

[0050] The agrochemical product of the invention is intended for agricultural use, and more broadly, for the sun protection of plants.

[0051] The agrochemical product can be applied by spraying, misting, powder dispersion, or any other foliar spray system, in order to limit the damage caused by solar radiation on the epidermis of plants.

[0052] The agrochemical product of the invention may be formulated in the form of micronized powder, in the form of gelled powder, or in the form of an aqueous suspension to be diluted in a spray tank. It can be applied in the form of a film of active particles in the fight against solar radiation and the support of the biological reactions which result from it.

[0053] The product of the invention may be applied, for example, during leaf development and / or during fruit development. It is applied to the leaves, preferably by spraying a suspension of the magnesium agent mixture. During fruit development, it can be advantageously applied to both leaves and fruits.

[0054] It advantageously makes it possible to achieve a higher level of vegetative activity than the sun protection agents of the prior art, in particular an increase in the rate of foliar emission and an improvement in plant growth.

[0055] Used at lower doses, or even half those used with the sunscreen agents of the prior art, the mixture of magnesium raw materials makes it possible to maintain the same productivity gain under light stress conditions thanks to an activity which extends over the entire light spectrum, from infrared to ultraviolet. In particular, the mixture of magnesium agents makes it possible to reduce the phenomenon of sunburn, to improve the aesthetic quality of the fruits, to increase the weight of the fruits, which contributes to the increase in the productivity of the crop by acting at multiple levels.

[0056] In a particular embodiment, the product is applied at a dose ranging from 0.1 kg / ha to 100 kg / ha per application, preferably from 10 kg / ha to 30 kg / ha per application, during periods of exposure to solar radiation during crop development, but also during storage. The application may take place every day to every month, preferably every 1 to 3 weeks, depending on weather conditions and crop development. The application will preferably be carried out using a sprayer. The dilution of the material will preferably be 5% to 10% w / w of water.

[0057] The crop may be chosen from vegetable crops, for example watermelon, melon, tomato, pepper, eggplant, cucumber, potato or salad, fruit crops, for example apple, pear, vine, apricot, nectarine, peach, lemon, mandarin, orange, olive tree, walnut tree, hazelnut tree, berries, strawberry, cherry, pineapple, banana, avocado, durian, cocoa or oil palm, field crops, for example maize, wheat, barley, sorghum, rapeseed, sugar cane and beetroot, ornamental crops such as flowers, and any other crop that may be affected by the sunscald phenomenon.

[0058] The invention also relates to the use of at least one first magnesium agent and at least one second magnesium agent as described above for controlling solar abiotic stress suffered by plant tissues, preferably chlorophyllous plant tissues.

[0059] Finally, a final object of the invention relates to an agricultural method for applying to a crop an agrochemical product in accordance with the preceding description. Example 1: Product according to the invention An agrochemical product was prepared consisting of 30% by volume of a first magnesium carbonate having a particle size between 0.1 and 10 microns (Agent Mg 1) and 70% by volume of a second magnesium carbonate having a particle size ranging from 10 to 110 microns (Mg 2 Agent), the particle size being defined here as the particle size distribution of the magnesium raw material. Characteristics of the product of the invention: - Whiteness index The whiteness index of the product Agent Mg 1 + Agent Mg 2 is greater than 75 (W C IE). - Particle size distribution The particle size distribution of the product of the invention was determined by sedimentometry using a Malvern brand device, model Mastersizer V 3.81. Figure 1 shows the particle size distribution of the agrochemical, with the percentage of a fraction of the particle volume on the ordinate, and the maximum size of the fraction on the logarithmic scale on the abscissa. - Reflectance The reflectance capacity of the product of the invention for ultraviolet and visible radiation was evaluated by obtaining the spectral reflectance signature using a Jasco spectrophotometer, model V-750. The obtained spectrum is reproduced in Figure 2. In the ultraviolet range, particularly UVb (280-315nm), 65% to 70% of the radiation is reflected by the product. In comparison, kaolin reaches a maximum reflectance of 40% in UVb. In the visible range, particularly in PARs where Chlorophylls a and b act at 430-445 nm and 645-660 nm, 76% and 78% of the radiation is respectively reflected by the product of the invention. Finally, in the near infrared range, starting at 700nm and measured up to 900nm, 70% and 75% of the radiation is reflected respectively. Example 2: Evaluation of the control of abiotic stress in greenhouses of the product of the invention and comparison with the prior art A greenhouse study was carried out under controlled conditions with artificial exposure according to the following protocol. Plant material: Rose de Berne tomato plants were overgrown until the fruiting stage in order to select plants with a homogeneous stage of development to begin the trial. Materials tested: Three micronized mineral powders were evaluated in this trial: - a micronized aluminum silicate (kaolin) with a whiteness index greater than 75 (WQE) and a D50 particle size less than 15 pm. - a product according to the invention (Product of the invention 1) containing 30% by volume of a magnesium carbonate with a particle size between 0.1 and 10 microns (Agent Mg 1) and 70% by volume of a magnesium carbonate with a particle size between 10 and 110 microns (Agent Mg 2). - a product according to the invention (Product of the invention 2) comprising a mixture of three magnesium agents including Agent Mg 1, Agent Mg 2 and a magnesium sulfate. Terms and conditions: The four modalities are presented in Table 1. Table 1 - Greenhouse study modalities The products were diluted in water at a dose of 5% by mass and sprayed to the point of runoff using a hand sprayer on the leaf surface and fruits. Terms : After 24 hours, the plants were placed in a growth chamber and exposed to abiotic stress (QO) using lights simulating the solar spectrum containing ultraviolet, visible and infrared radiation. Ratings: Observations were carried out on days 9 and 16 to assess the number of leaves produced under stress conditions. Results: The results presented in Figure 3 show a reduction in the rate of foliar emission with the kaolin modality compared to the control (untreated), this can be explained by a significant coverage of the powder on the leaves thus reducing the photosynthetic activity of the plant which therefore impacts the metabolism of the plant. The contribution of the product of invention 1 alone allows a higher level of vegetative activity than the control, but the growth is further improved by the product of invention 2. Example 3: Evaluation of the control of abiotic stress in the field with the product of the invention and comparison with the prior art A field study was carried out under natural conditions and in the area of ​​occurrence according to the following protocol. Plant material: The trial was conducted in the field on watermelons of the Nikita variety. Materials tested: Two micronized mineral powders were evaluated in this trial: B- a kaolin known in agriculture for its sun protection effect C- the product according to the invention described in Example 1 comprising a mixture of two magnesium agents. Terms and conditions: The three modalities are presented in Table 2. Table 2 - Field study modalities Terms : These treatments are applied using a foliar sprayer during fruit development and again when 20% of the fruit has reached maturity. Ratings: The percentage of the fruit surface affected by sunburn as well as the weight and class of the fruit are assessed at harvest, according to current standards. Results : The results are shown in Figures 4, 5 and 6. The use of the product of the invention, at half the dose, makes it possible to maintain the same productivity gain under light stress conditions compared to kaolin, used as a reference. This is explained by the combination of the physical and biological effect of the product of the invention. Indeed, Figure 4 shows the ability of the product of the invention to reduce the phenomenon of sunburn by 60% compared to the untreated control. In addition, the evaluation of the fruit category related to their level of aesthetic quality (Figure 6), as well as the measurement of the fruit weight (Figure 5) shows the impact of the product of the invention on the productivity of the crop. These results show that the product of the invention allowed a gain of +7% of the weight of the watermelon equivalent to +185g per fruit, in comparison with the untreated control, and +162g compared to kaolin. Similarly, the evaluation of the fruit category (Figure 6) shows an improvement in the quality of the fruits produced with +13% in Class 1 compared to the untreated control, thus fruits in Class 2, less profitable, were able to achieve better quality thanks to the application of the product of the invention.

Claims

Claims

1. Agrochemical product in the form of a powder of particles comprising a mixture of at least one first magnesium agent and at least one second magnesium agent for controlling abiotic solar stress suffered by a crop, - the first magnesium agent having a particle size ranging from 10 microns to 150 microns, preferably ranging from 10 microns to 110 microns, and being a magnesium material comprising at least one compound chosen from magnesium carbonate, dolomite, magnesium oxide, magnesium silicate, magnesium hydroxide, and their hydrates, and - the second magnesium agent, different from the first magnesium agent, being chosen from: a) a water-soluble magnesium agent chosen from magnesium materials comprising at least one compound chosen from magnesium sulfate and its hydrates, magnesium nitrate and its hydrates, magnesium chloride and its hydrates, and organic magnesium salts chosen from magnesium bisglycinate, magnesium citrate, magnesium aspartate, magnesium lactate, magnesium glycerophosphate, magnesium pidolate and magnesium gluconate, and from b) a magnesium agent whose particle size is between 0.1 and 10 microns and being a magnesium material comprising at least one compound chosen from magnesium carbonate, dolomite, magnesium oxide, magnesium silicate, magnesium hydroxide and their hydrates.

2. Agrochemical product according to claim 1, characterized in that the whiteness index of the mixture is greater than 60, preferably greater than 75.

3. Agrochemical product according to claim 1, characterized in that the mixture has a particle size ranging from 0.1 micron to 150 microns, preferably from 0.1 micron to 110 microns, and a D50 of between 5 microns and 40 microns.

4. An agrochemical product according to claim 1, characterized in that the first magnesium agent is a magnesium material comprising magnesium carbonate and the second magnesium agent is a magnesium material comprising magnesium carbonate.

5. Agrochemical product according to claim 1, characterized in that the first magnesium agent represents between 60% and 80% of the total volume of the product, and in that the second magnesium agent represents between 20% and 40% of the total volume of the product.

6. Agrochemical product according to claim 1, characterized in that it consists essentially of magnesium materials.

7. Use of the combination of at least one first magnesium agent and at least one second magnesium agent according to one of the preceding claims for controlling solar abiotic stress suffered by plant tissues.

8. Agricultural method of applying to a crop an agrochemical product according to one of claims 1 to 7.

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