Concentrated algae extract, method for its production and its use in agriculture

Description

[0001] The present invention relates to a concentrated seaweed extract having a percentage of dry matter of between 6 and 100%, its preparation process and its uses alone or in combination with another nutritive, biostimulant or phytosanitary technology, in particular to promote the emergence, growth, development and reproduction of plants and to prevent birds from eating the seeds. The invention also relates to a method of applying the concentrated seaweed extract of the present invention and a seed coated with said extract.

[0002] Increasing yields is a key concern for farmers. However, yields depend largely on the proper development of the plant and, consequently, its growth and good health.

[0003] Plant growth is directly linked to the absorption and assimilation of mineral elements as well as hormonal flows governing the elongation and differentiation of plant tissues. Nutrients and hormones therefore play an essential role in plant growth. Due to their inability to move, plants have established active and activatable mechanisms allowing them to make the best use of the resources available to promote their growth. In order to increase this growth, fertilizers are used.

[0004] Seaweed has been used for many years as an organic amendment on various soil types and different vegetable and cereal crops. Seaweed extracts are used as a biostimulant, most often sprayed on plant leaves. Many beneficial effects associated with the use of seaweed extract in agriculture have been observed, including increased yield, nutrient intake, resistance to frost and stress conditions, improved fruit shelf life, and reduced attacks by fungi and insects.

[0005] Seaweed extracts are also known to improve seed germination, particularly by promoting plant emergence. Indeed, as soon as they emerge, seedlings are susceptible to pathogenic microorganisms, such as fungal species like Rhizoctonia spp., Pythium spp., or bacteria that cause a disease called damping-off. Attacked seedlings lie on their side, as if the base of the stem had been pinched. Air humidity and low temperatures promote the occurrence of damping-off.

[0006] Many algae extracts are marketed for use in agriculture. For example, the Applicant has described, in patent EP 0538091, a composition derived from marine algae obtained according to a process comprising the following steps: a) basic hydrolysis of at least one brown algae in the presence of a reducing agent, at a temperature between 50 and 100°C, for a period between 4 and 8 hours; b) neutralization of the hydrolyzate thus obtained with a strong acid until a pH between 6 and 8 is obtained; c) filtration; d) optionally diafiltration or electrodialysis of the permeate obtained at the end of step c); and e) optionally reduction to its powder of the permeate obtained at the end of step c), or of the retentate obtained at the end of step d).

[0007] However, due to the basic hydrolysis of the algae under hot conditions in the presence of a reducing agent, certain compounds of the intracellular liquid of the algae are not preserved, in particular polysaccharides, lipids, proteins, and polyphenols, which reduces the biostimulant properties of the composition obtained with the process described above.

[0008] The present inventors have found that an algae extract in which the compounds of the intracellular liquid of the algae are preserved exhibits excellent biostimulant activity when concentrated to a certain percentage of dry matter. Surprisingly, the Applicant has found that, following application in comparable quantities, the concentrated algae extract of the invention is more effective than a diluted extract in stimulating emergence and promoting plant growth. In addition, when the concentrated algae extract is used to coat seeds, these are less attacked by birds than uncoated seeds.

[0009] The subject of the present invention is a concentrated algae extract having a percentage of dry matter of between 6 and 100%, preferably between 9 and 70%, more preferably between 12 and 50% and containing 0 to 1% by weight of alginate and cellulose relative to the weight of said extract.

[0010] A second object of the present invention is a process for preparing this concentrated algae extract according to the invention comprising the following steps: crush the algae until cell bursting; homogenize the ground algae in aqueous solution; remove the alginate and cellulose by flocculation and filtration; possibly adjust the pH of the filtrate; concentrate the filtrate to reach a percentage of dry matter between 6 and 100%, preferably between 9 and 70%, more preferably between 12 and 50%.

[0011] Another subject of the present invention is a method for promoting the emergence, growth, development and / or reproduction of a plant, characterized in that the extract according to the invention or prepared according to the method of the invention is applied by infiltration into the soil, sprayed onto the leaves of the plant, applied to a seed before sowing or applied to the roots of a seedling, in particular by pralining, before planting.

[0012] Yet another object of the present invention is the use of an extract according to the invention or prepared according to the process of the invention, to promote the growth of plants.

[0013] The present invention also relates to the use of an extract according to the invention or prepared according to the process of the invention, to stimulate the emergence of plants.

[0014] A sixth object of the present invention is the use of an extract according to the invention or prepared according to the process of the invention, as a bird repellent.

[0015] Finally, the invention also relates to a seed coated with an extract according to the invention or prepared according to the process of the invention.

[0016] The concentrated algae extract of the present invention is in particular an aqueous extract or a dry extract, having a percentage of dry matter of between 6 and 100%, preferably between 9 and 70%, more preferably between 12 and 50%.

[0017] The percentage of dry matter, within the meaning of the present invention, is calculated using the following formula: m sèche m hydratée × 100 Or M dry is the mass of material remaining after drying; and hydrated mis the mass of the seaweed extract before drying. The concentrated seaweed extract of the present invention is free of alginate and / or cellulose. Thus, the seaweed extract according to the invention comprises intracellular seaweed liquid obtained after bursting the seaweed cell walls and removing them by flocculation. The concentrated seaweed extract of the present invention contains 0 to 1% by weight of alginate and cellulose relative to the weight of said extract.

[0018] The algae from which the concentrated extract of the present invention is obtained may in particular be chosen from Ascophyllum nodosum, Fucus vesiculosus, Laminaria digitata, Laminaria hyperborea, Laminaria saccharina, Eklonia maxima, sargassum spp. and their mixtures. According to a particular embodiment, said algae is Ascophyllum nodosum.

[0019] The concentrated algae extract of the present invention may in particular have a pH of between 1.5 and 9, preferably between 2 and 7, more preferably between 2.5 and 3.

[0020] The concentrated seaweed extract of the present invention comprises intracellular seaweed liquid. It may in particular comprise one or more compounds chosen from polysaccharides such as in particular laminarin and fucans; free and conjugated sugars; polyphenols, mannitol; growth hormones; lipids; proteins; amino acids; vitamins; betaines; sterols; glucuronic acid, and mineral salts. According to a particular embodiment, the concentrated seaweed extract of the present invention comprises laminarin; fucans; lipids; proteins; and polyphenols.

[0021] According to a particular embodiment, the concentrated algae extract of the present invention can be formulated in a composition comprising said extract and at least one compound chosen from a gelling agent, a thickener, a phytosanitary product, a second plant and / or algae extract, minerals, a surfactant, an oil, a preservative, and mixtures thereof.

[0022] The concentrated algae extract of the present invention can in particular be obtained by the process described below.

[0023] The method for preparing a concentrated algae extract according to the present invention comprises the following steps: crush the algae until cell bursting; homogenize the ground algae in aqueous solution; remove the alginate and cellulose by flocculation and filtration; possibly adjust the pH of the filtrate; concentrate the filtrate to reach a percentage of dry matter between 6 and 100%, preferably between 9 and 70%, more preferably between 12 and 50%.

[0024] The method of the present invention does not include a hydrolysis step, in the presence of a reducing agent, for example at a temperature between 50 and 100°C, for a period of between 4 and 8 hours. This in fact makes it possible to preserve the compounds of the intracellular liquid of the algae, in particular the polysaccharides.

[0025] The grinding step allows the cell walls of the algae to burst, thus releasing the intracellular algae fluid. The grinding step is preferably carried out on fresh algae, i.e. algae harvested less than 24 hours ago.

[0026] The homogenization step of the algae ground material can be carried out in particular by adding water at a rate of 1 to 2 L of water per kg of algae ground material.

[0027] The flocculation and filtration step makes it possible in particular to eliminate the residues of the cell walls of the algae in order to collect the intracellular liquid of the algae. The residues of the cell walls of the algae can in particular precipitate by flocculation by adding an acid, in particular hydrochloric acid, to the ground algae. According to a particular embodiment of the present invention, the acid is added so as to obtain a pH of between 1.5 and 4, preferably between 2 and 3.5, more preferably between 2.5 and 3.

[0028] The acidified mixture is then filtered to remove alginate and cellulose flocs larger than 40 µm.

[0029] The pH of the filtrate may optionally be adjusted by adding an acid or a base so as to reach a pH between 1.5 and 9, preferably between 2 and 7, more preferably between 2.5 and 3.

[0030] The filtrate concentration step can be carried out in various ways, such as reverse osmosis, water evaporation, algae enrichment or centrifugation.

[0031] Reverse osmosis is a membrane separation technique based on a diffusion selectivity process. Two algae extracts of different concentrations are placed on either side of a water-permeable membrane. When pressure is applied to the more concentrated algae extract, some of the water contained in the more concentrated extract migrates to the less concentrated extract.

[0032] Water evaporation can be achieved, for example, by heating the algae extract under reduced pressure, for example using a rotary evaporator. Heating can be carried out between 40 and 90°C, preferably between 60 and 80°C.

[0033] The enrichment in algae can in particular be carried out by replacing, in the homogenization step of the algae ground material of the process according to the invention, the water with a suspension of algae obtained by the process according to the invention.

[0034] Centrifugation can be achieved, for example, by subjecting the seaweed extract to centrifugal force in a machine rotating at high speed.

[0035] Preferably, the filtrate concentration step is carried out by evaporation of water.

[0036] The concentrated algae extract according to the present invention is advantageously used in agriculture where it finds numerous applications depending on the type of plant to which it is applied and the period of the plant cycle where it is used.

[0037] The concentrated algae extract of the present invention can in particular be used alone or in combination with a nutritive, biostimulant or phytosanitary composition.

[0038] The plants on which the concentrated seaweed extract of the present invention can be used are agronomically useful plants, for example vegetable, fruit and cereal crops, and ornamental plants. The agronomically useful plants are angiosperms selected from the group comprising Apiaceae, Asteraceae, Brassicaceae, Chenopodiaceae, Convolvulaceae, Cucurbitaceae, Fabaceae, Gramineae, Liliaceae, Polygonaceae, Rosaceae, Solanaceae, Poaceae, Vitaceae. According to a particular embodiment, the concentrated seaweed extract of the present invention is used on tomatoes, rice, soybeans, fruit trees, vines, wheat or corn.

[0039] Thus, when the concentrated seaweed extract of the present invention is used to promote plant growth, said extract may in particular be applied by foliar spraying or by soil application or root infiltration. Applications may be made throughout the growth of the plant, once or several times per week. Very interesting results have been demonstrated on tomato plants and on corn plants.

[0040] When the concentrated seaweed extract of the present invention is used to stimulate plant emergence and / or to provide a bird repellent effect, said extract may in particular be applied to the seeds before they are planted or to the young seedlings just after emergence. The seeds may in particular be coated with the concentrated seaweed extract of the present invention. The coating may, for example, be carried out by wetting the seeds with said extract and allowing them to dry, preferably at room temperature. The application may be carried out at a rate of 10 to 120 g, preferably 20 to 110 g, more preferably 30 to 105 g of concentrated seaweed extract per 100 kg of seeds. Very interesting results have been demonstrated on corn seeds.

[0041] The coated seed which is the subject of the present invention may in particular be prepared as described in the preceding paragraph. Coating the seed with the concentrated seaweed extract of the present invention allows for faster emergence of the plant and makes it more resistant to damping-off, compared to uncoated seeds. In addition, the coated seeds according to the present invention are much less attacked by birds, such as in particular crows, pigeons, larks, partridges and pheasants, compared to uncoated seeds.

[0042] The invention will be described in more detail below with the aid of the following examples which are given for illustration purposes only. FIGURES

[0043] There figure 1is a schematic representation of the number of corn plants obtained 3 weeks after sowing uncoated corn seeds, corn seeds coated with an algae extract of the present invention or corn seeds coated with a conventional fungicide as described in Example 4. The figure 2 is a schematic representation of the number of corn plants obtained 3 weeks after sowing uncoated corn seeds, coated with an algae extract of the present invention or coated with a conventional fungicide as described in Example 5. EXAMPLES Example 1: Preparation of a concentrated algae extract

[0044] An algae extract Ascophyllum nodosum having a percentage of dry matter of 5.1%, called GOACTIV by the Applicant company, is concentrated by evaporation of water by heating the extract to 50°C in a rotary evaporator under vacuum (water pump) until the percentage of dry matter reaches 13%. Example 2: Application of concentrated seaweed extract to tomato plants

[0045] On tomato plants, at the 3-leaf stage (3 weeks), spray the leaves once a week with a quantity of extract per plant as indicated in the following table: Seaweed extract GOACTIV Comparison According to the invention (Example 1) % dry matter 5.1% 13% Quantity of extract sprayed per plant 0.03 mg 0.01 mg

[0046] The tomato plants are therefore treated with comparable amounts of each extract.

[0047] After 5 weeks of treatment, tomato plants treated with the concentrated seaweed extract of the present invention (Example 1) were taller and bushier than plants treated with the non-concentrated seaweed extract (GOACTIV). For comparable amounts of extract applied, the concentrated seaweed extract of the present invention was therefore more effective in promoting the growth of tomato plants than a more dilute extract. Example 3: Coating corn seeds with concentrated seaweed extract

[0048] 100 kg of corn seeds are wetted with 100 g of concentrated seaweed extract prepared in Example 1 in a rotary mixer. The seeds are then left to dry at 20-25°C for 24 hours. Example 4: Effect of seed coating on corn plant emergence

[0049] The coated corn seeds prepared in Example 3 are sown on plots of 20 m 2. A control is carried out with untreated corn seeds. A comparative test is carried out with corn seeds coated with a conventional fungicide comprising 25 g / l of fludioxonil and 9.7 g / l of metalaxyl-M.

[0050] 3 weeks after sowing, the number of corn plants is counted. The results are presented in Figure 1 . It is noted that the emergence of corn plants is promoted when the seeds are coated with the concentrated seaweed extract prepared according to Example 1 compared to uncoated seeds or seeds coated with the fungicide. Example 4 was reproduced and gave similar results. Example 5: Bird repellent effect of seed coating

[0051] During one of the experiments according to Example 4, the field suffered a particularly aggressive attack by crows. The birds attack the seeds buried in the soil, which leads to a decrease in the number of healthy corn plants compared to the number of seeds planted.

[0052] The results are presented at the Figure 2 , the values ​​on the y-axis being expressed as a percentage of healthy corn plants compared to the theoretical number of plants.

[0053] A clear difference in the level of attack between the control plots or those treated with the fungicide and the plots whose seeds were coated with the concentrated seaweed extract of Example 1 was observed. Thus, the plots sown with seeds treated with the concentrated seaweed extract of Example 1 were relatively spared from birds.

[0054] The concentrated seaweed extract of the present invention therefore has a bird repellent effect.

[0055] Example 5 was reproduced and gave similar results.

Claims

1. Method for preparing a concentrated algae extract, characterised in that it contains 0 to 1% by weight of alginate and cellulose relative to the weight of said extract, said method comprising the following steps: - grinding the algae until the cells burst; - homogenising the algae ground material in an aqueous solution; - removing the alginate and cellulose via flocculation and filtration; - optionally adjusting the pH of the filtrate; - concentrating the filtrate to achieve a percentage of dry matter of between 6 and 100%, said method not comprising a hydrolysis step in the presence of a reducing agent.

2. Method according to claim 1, characterised in that the filtrate concentration step is carried out by reverse osmosis, by evaporation of water, by enrichment in algae or by centrifugation.

3. Concentrated algae extract that can be obtained via the method which is the subject matter of any one of claims 1 or 2, characterised in that it has a percentage of dry matter of between 6 and 100% and in that it contains 0 to 1% by weight of alginate and cellulose relative to the weight of said extract.

4. Extract according to claim 3, characterised in that the algae is chosen from Ascophyllum nodosum, Fucus vesiculosus, Laminaria digitata, Laminaria hyperborea, Laminaria saccharina, Ecklonia maxima, Sargassum spp. and mixtures thereof.

5. Extract according to claim 3 or 4, characterised in that it has a pH of between 1.5 and 9.

6. Method for promoting the emergence, growth, development and / or reproduction of a plant, characterised in that the extract as defined in any one of claims 3 to 5 is applied by infiltration into the soil, sprayed on the leaves of the plant, applied to a seed before sowing or applied to the roots of a seedling, in particular by pralinage, before planting.

7. Use of an extract as defined in any of claims 3 to 5, for promoting the growth of plants.

8. Use of an extract as defined in any of claims 3 to 5, for stimulating the emergence of plants.

9. Use of an extract as defined in any of claims 3 to 5, as a bird repellent.

10. Seed coated with an extract as defined in any of claims 3 to 5.