Background Art Plants respond to external stress impulses by production of hormones which signalize the stress inside the plant as well as among plants. Salicylic acid, jasmonic acid and their derivatives belong among this type of hormones. Plants use signaling pathways of these acids for the activation of induced systemic resistance (ISR) and systemic acquired resistance (SAR) (Pieterse C. M. J. et al., Nat. Chem. Biol. 2009, 5, 308-316). In agricultural practice, the above mentioned compounds are applied for example to enhance the resistance against pathogens or to induce secondary metabolite production (WO 2005/118508) or to increase crop yield. The procedure is called elicitation and the above mentioned compounds are classified as elicitors. The application of the above mentioned compounds is also used to intensify secondary metabolite production in plant cell cultures. They are used for example to isolate pharmacologically bioactive components or their structural precursors, further used for drug production by synthetical modifications. It is typically performed by an addition of the elicitor into a hydroponic solution of the culture, which often leads to a multiple increase of the secondary metabolites production (Namdeo A. G., Pharmacogn. Rev., 2007, 1(1), 69-79).

Even though the mechanisms of the metabolism and effects of these substances are intensively studied, their practical applications cause problems related mainly to their physico-chemical properties, such as volatility or a charge present in the molecule. While volatile substances (such as methyl salicylate, methyl jasmonate) quickly evaporate from the plant surface after the application, which leads to gradual loss of efficiency, the initial acids are not very well resorbed into leaves because they are present in anionic form. It is possible to increase the efficiency to induce defensive reactions of natural substances by introducing suitable substituents into the molecules, for example halogens (Silverman, F. P., J. Agric. Food Chem. 2005, 53, 9775-9780). Even after the above mentioned optimizations, the above discussed disadvantages remain. In 1992, the so-called mesoporous materials were discovered (Kresge C. T. et al., Nature 1992, 359(6397), 710-712). Their structure contains 2 to 30 nm pores and such materials have large surfaces (from 700 to 1500 m ² /g). Mesoporous materials are usually prepared in a two-step procedure, including 1) growth of liquid crystal precursors, in which the particular phase components, containing nano-sized cavities or channels, are organized by a self-assembly of surfactants, 2) formation of stable mesoporous pores (mesopores), consisting of cavities resulting from the removal of surfactants either by heating or chemically (Slowing I. I. et al, J. Mater. Chem. 2010, 20, 7924-7937). The resulting materials can have different structure arrangements, depending on the method of preparation. Materials with rather small pore sizes (2 to 5 nm) have for example the following arrangements: plane hexagonal (space group ρβτηπι, the typical material symbol is MCM-41), bicontinuous cubic {laid, MCM-48) or lamellar (p2, MCM-50, SBA-4). Greater pore sizes (6 to 20 nm) have for example arrangements such as hexagonal planar (p6mm, SBA-15), three-dimensional cubic Fm m, IBN-2; Pm3m, SBA-11 ; Pm3n, SBA-1 or SBA-6; Fd m, FDU-2) or three-dimensional hexagonal (P6 ₃ /mmc, SBA-2 or SBA-7) (Wan Y. and Zhao D., Chem. Rev. 2007, 107(7), 2821- 2860).

Mesoporous materials can be prepared in acid or base media and can be further chemically modified on the outer surface as well as inside the pores. The pores can enclose various chemical compounds, therefore leading to materials which enable their gradual release. Because of the above mentioned structural variability, it is possible to suitably tune the properties of mesoporous materials for various molecules and various purposes (Slowing 1. 1, et al., J. Mater. Chem. 2010, 20, 7924-7937).

It is indubitable that there remains the need to improve the efficiency of materials on the basis of salicylic and jasmonic acids for agricultural applications.

Disclosure of the Invention

The invention solves the problems of the prior art by providing novel mesoporous compositions containing derivatives of jasmonic and/or salicylic acids and the use and applications thereof in agriculture. It was found that the use of mesoporous particles significantly increases the efficiency of jasmonic acid derivatives and/or salicylic acid derivatives when applied on plants. The material is easy to prepare and ecologically harmless. The presence of silicon in these nano- or micro-particles is advantageous for plants because silicon itself is an important building component of plants, a mineral support of their mechanical resistance, increases the plant's tolerance to biotic and abiotic stresses and increases the natural immunity of plants.

The invention refers to mesoporous particles containing at least one compound of general formula (I)

wherein R ¹ is selected from the group comprising hydrogen, cation selected from the group comprising alkali metals and ammonium, linear or branched Q-C^ alkyl (preferably C C ₆ alkyl), linear or branched Ci-C ₁₈ alkyl (preferably Q-C6 alkyl) substituted with halogen, hydroxy, amino or sulphonic group, C ₃ -C ₈ cycloalkyl, phenyl, phenyl substituted in at least one of the positions 2, 3, 4, 5 and 6 with substituents selected from the group comprising C1-C5 alkoxyl, Ci-C ₅ alkyl, halogen and hydroxy group;

R ² is selected from the group comprising hydrogen, Q-Qs acyl (preferably Ci-C ₆ acyl), linear or branched C Cig alkyl (preferably Ci-C ₆ alkyl), linear or branched Cj-Cis alkyl (preferably C _\ -C alkyl) substituted with halogen, hydroxy, amino or sulphonic group, C ₃ -C ₈ cycloalkyl, or glucoside;

R ³ , R ⁴ , R ⁵ and R ⁶ are independently selected from the group comprising hydrogen, halogen, hydroxy or nitro group, and/or at least one compound of the general formula (II)

wherein R is selected from the group comprising hydrogen, linear or branched C1-C4 alkyl, cation selected from the group comprising alkali metals, ammonium, dialkylammonium, trialkylammonium and tetraalkylammonium, wherein each of the alkyls can have independently 1 to 4 carbon atoms. The mesoporous particles of the invention are preferably particles on the basis of Si0 ₂ with a structural arrangement selected from the group comprising: plane hexagonal ip6mm, MCM-41), bicontinuous cubic {laid, MCM-48) and lamellar (p2, MCM-50, SBA-4). The particles can have size in the range of from 10 nm to 10 μηι and can be modified with other groups, such as amino or carboxyl groups, on the surface as well as inside the mesoporous channels. The particles can be prepared using known procedures, summarized for example in the article Wan Y. a Zhao D., Chem. Rev. 2007, 107(7), 2821-2860.

Object of the invention is the use of the particles according to the invention for the activation of induced systemic resistance, systemic acquired resistance, activation of defence reaction of plants against pathogens and stress, induction of production of secondary metabolites and/or to increase a crop yield and quality of production.

The invention also provides a method of activation of the induced systemic resistance, the systemic acquired resistance, the activation of the defence reaction of plants against pathogens and stress, the induction of the production of secondary metabolites and/or the increase of the crop yield and the quality of production, wherein at least one type of the mesoporous particles according to the invention is applied onto the plants growing in soil, in hydroponic media or in an artificial substrate, or into the soil or into the hydroponic media.

Another object of the present invention is a composition for the protection of plants, comprising at least one type of the mesoporous particles according to the present invention.

The composition can further contain additional auxiliary substances, such as additives, surfactants, auxiliary solvents, antifoaming agents, colorants and supplementary agents.

An additive is a natural or a synthetic organic or inorganic compound, which, in a mixture with particles according to the invention, simplifies their application. The additive has to be inert and suitable for use in agriculture. Kaolin, montmorillonite, attapulgite, bentonite, calcite, dolomite, natural or synthetic silicates and aluminosilicates, colloid nanoparticles of silica gel or Si0 ₂ , fertilizers, water or mineral and vegetable oils and derivatives thereof can serve as examples. The above mentioned additives can be used also in mixtures and the amount of the additive in the composition can preferably be in the range of from 1 to 90 % (w/w).

A surfactant is a dispersant, a wetting agent or an emulsifier of an ionic or non-ionic nature. The examples of surfactants are salts of naphtalenesulphonic, phenolsulphonic and ligninsulphonic acids, polycondensates of ethyleneoxide with fatty alcohols or amines, substituted phenols (mainly alkylphenols and arylphenols), salts of sulpho succinic acid esters, salts of alkylbenzenesulphonic acid, derivatives of taurine (mainly alkyltaurates), phosphoric acid esters with polyethoxy alcohols or phenols, fatty acid esters with polyols and derivatives of the above mentioned compounds containing sulphate, sulphonate or phosphate group. The content of the surfactant in the compositions can preferably be in the range of from 2 to 60 % (w/w).

As an auxiliary solvent is understood a solvent miscible with water, for example dipropylene glycol monomethyl ether, glycerol, propylene glycol, butylene glycol, ethanol, methyl lactate, ethyl lactate, methyl glycolate, ethyl glycolate, tetrahydrofurfuryl alcohol, propylene carbonate, glycerol formal, N-methylpyrrolidone, dimethyl sulphoxide etc.

An anti-foaming agent is any compound, which decreases the foam stability.

Supplementary agents are colloid stabilizing agents, adhesives, binding materials and rheology modifiers. Generally, the particles according to the invention can be combined with any liquid or solid additive, which is commonly used in pesticide or fertilizer formulation.

The composition according to the invention can preferably contain mesoporous particles according to the invention in the amount of from 1 to 99 % (w/w). In the case of formulation as a wettable powder, it can contain preferably from 1 to 95 % (w/w) of mesoporous particles. In the case of a liquid formulation, it contains preferably from 1 to 50 % (w/w) of mesoporous particles, most preferably from 5 to 35 % (w/w) of mesoporous particles. The compositions according to the invention can be prepared in different forms (such as wettable powders, granules or microgranules dispersible in water, suspensions, suspension concentrates, pastes dispersible in water, emulsifiable powders, emulsifiable granules or microgranules, emulsifiable suspension concentrates, microemulsions, colloid solutions containing mesoporous nano- or microparticles according to the invention) suitable directly or after dilution for agricultural applications. Wettable powders can be filled in soluble coatings, which prevent the user from inhaling thereof, and the composition from undesirable dust formation.

The compound of the general formula (I) is preferably selected from the group comprising methyl salicylate, ethyl salicylate, salicylic acid, salicylic acid glucoside, salicylic acid methyl ester glucoside, methyl 3-chlorosalicylate, methyl 4- chlorosalicylate, methyl 3-fluorosalicylate, methyl 3,5-dichlorosalicylate, methyl 3,5- difluorosalicylate, methyl 3-chloro-5-fluorosalicylate, methyl 5-chloro-3-fluorosalicylate, 3-chlorosalicylic acid, 4-chlorosalicylic acid, 3 -fluoro salicylic acid, 3,5-dichlorosalicylic acid, 3,5-difluorosalicylic acid, 3-chloro-5-fluorosalicylic acid, 5-chloro-3-fluorosalicylic acid, 3-chlorosalicylic acid glucoside, 4-chlorosalicylic acid glucoside, 3-fluorosalicylic acid glucoside, 3,5-dichlorosalicylic acid glucoside, 3,5-difluorosalicylic acid glucoside, 3-chloro-5-fluorosalicylic acid glucoside and 5-chloro-3-fluorosalicylic acid glucoside.

The compound of the general formula (II) is preferably selected from the group comprising jasmonic acid, methyl jasmonate and ethyl jasmonate. The preparation is preferably applied on cereals of the Gramineae family, such as wheat, barley, oat, rye or triticale.

Examples Example 1

Preparation of mesoporous particles MCM-41

Cetyltrimethylammonium bromide (CTAB, 2.04 g, 5.32 mmol) was dissolved in 960 ml of water. 7.0 ml of 2 M sodium hydroxide was added to the solution and the mixture was stirred for 15 minutes. 10.0 ml (43.9 mmol) of tetraethoxysilane was then added, and the reaction mixture was vigorously stirred at 80 °C for 2 hours. The resulting white precipitate was filtered off, thoroughly washed with ethanol and vacuum-dried for 20 hours. CTAB was removed from the product by heating of the material at 60 °C with 1000 ml of methanol containing 10 ml of concentrated hydrochloric acid for 6 hours. The resulting particles of MCM-41 type were filtered off, washed four times with ethanol and vacuum-dried.

Example 2

Preparation of particles containing methyl salicylate (meso-MS)

50 mg of methyl salicylate dissolved in 100 ml of absolute ethanol were added to 5 g of prepared MCM-41 particles. The suspension was stirred for 2 days. The precipitate was then filtered off, washed with ethanol and air-dried at room temperature and atmospheric pressure.

Example 3

Preparation of particles containing methyl jasmonate (meso-MJ) 228 mg of methyl jasmonate dissolved in 100 ml of absolute ethanol were added to 5 g of prepared MCM-41 particles. The suspension was stirred for 2 days. The precipitate was then filtered off, washed with ethanol and air-dried at room temperature and atmospheric pressure. Example 4

Preparation of particles containing methyl 3-chlorosalicylate

50 mg of methyl 3-chlorosalicylate dissolved in 100 ml of absolute ethanol were added to 5 g of prepared MCM-41 particles. The suspension was stirred for 2 days. The precipitate was then filtered off, washed with ethanol and air-dried at room temperature and atmospheric pressure.

Example 5

Test of efficiency on cereals In the years 2010 and 2011, field testing on winter wheat {Triticum aestivum L.) and on spring barley (Hordeum vulgare L.) were set up. The experimental area was chosen in a warm, sugar beet region with sufficient amount of precipitations, on a brown earth type of a soil. The plants were treated with common agricultural technology. Mesoporous particles meso-MJ and meso-MS, prepared according to Examples 2 and 3, were applied in a form of a foliar spray in doses according to Table 1, in a growth stage BBCH 49. Solutions of methyl salicylate and methyl jasmonate in corresponding concentrations were used as a positive control. A foliar spray with pure water served as a negative control. After the vegetation season finished, the mature crops were harvested and the yield was determined. In both cases, a positive effect of the mesoporous particles on the crop yield was proved (see Table 1), and, simultaneously, no phytotoxic effects were observed. The crop yield of both tested cereals, treated with meso-MJ and meso-MS (enclosed in mesoporous particles) was always higher in comparison with control samples, i.e. cereals treated with water only or cereals treated with methyl jasmonate or methyl salicylate not enclosed in mesoporous particles.

Table 1 : Crop yields. MJ - methyl jasmonate, MS - methyl salicylate, meso - substance enclosed in mesoporous particles. Listed concentrations of MJ and MS correspond to their final concentrations in a foliar spray (amount of 250 1/ha) and represent the total concentrations of MJ or MS, respectively. meso-MJ MJ meso-MS MS Yield % of

Crop Year

[μΜ] [μΜ] [μΜ] [μΜ] [t/ha] control

0.2 7.48 106.8

0.2 7.18 102.5

2010 50 7.50 107.2

50 7.32 104.6

Winter 7.00 100.0 wheat 0.2 8.38 107.3

0.2 8.08 103.5

2011 50 8.60 110.1

50 8.06 103.2

7.81 100.0

Spring 0.2 8.61 106.2

2010

barley 0.2 8.25 101.7