Water-retaining material for growing plants and water-retaining agent comprising such a water-retaining material

Abstract

The invention relates to a water-retaining material for growing plants, referred to as a water-retaining agent, comprising, by weight of dry matter, between 90 and 100% of at least one partially acetylated polysaccharide. The at least one polysaccharide comprises, by weight of dry matter, between 6 and 18% of acetyl groups. The water-retaining agent further comprises between 0 and 10% of one or more additives. The one or more additives comprise one or more fertilisers and / or one or more mycorrhizae and / or one or more rhizobia.

Description

DESCRIPTION Title: Water-retaining material for plant crops and water-retaining material comprising such a water-retaining material technical field [OOO1] The present invention belongs to the field of water retainers, water grain or water crystal.

[0002] Water retainers are commonly semi-permeable polymers.

[0003] Water-retaining agents, when brought into contact with water, swell with water to form hydrogels. The water retained by the agent can then be released over time.

[0004] Thus, some of these water-retaining materials are used as water-retaining agents for plant cultivation. In practice, these agents are introduced into the soil within or near the root system of plants.

[0005] The present invention also relates to water-retaining agents for plant cultivation. State of the art

[0006] Water resources are becoming scarce in most countries of the world. This situation is particularly acute in Europe, and especially in the southern European countries, which are and will be the most impacted by climate change.

[0007] The reduction in rainfall volumes associated with the increase in intense rainfall events necessitates adapting cultivation methods for plants as a whole.

[0008] In fact, the cultivation of agricultural plant species, and in particular the maintenance, or at least the limitation of the decline in production yields, constitutes a major challenge for the coming decades.

[0009] Water-retaining agents based on synthetic polyacrylamides derived from petrochemicals are known from the prior art. In most cases, these water-retaining agents are based on polyacrylates.

[0010] However, due to a lack of impact studies and the proven toxicity of the monomers that make up water-retaining agents, there is growing suspicion regarding their toxicity. Indeed, the monomers of these agents are classified as carcinogenic, mutagenic, neurotoxic, and reprotoxic. Furthermore, some studies show the presence of acrylamide monomers in vegetables grown using synthetic water-retaining agents. Consequently, the European Union has banned the use of synthetic water-retaining agents in crops intended for human consumption.

[0011] In some cases, mineral-based water-retaining agents, such as those based on silica or alumina, are also used, but these have a considerably lower water retention capacity than polymeric water-retaining agents. Indeed, the water retention capacity of mineral-based water-retaining agents is on the order of 1 to 2 by weight, while that of polymeric water-retaining agents is on the order of 200 to 500 by weight.

[0012] One object of the present invention is to remedy at least one of the drawbacks of the prior art.

[0013] Another aim of the invention is to offer: - water-retaining material for plant crops and a water-retaining agent for plant crops, and / or - water-retaining material for plant crops and a non-toxic water-retaining agent for plant crops, and / or - water-retaining material for plant crops and a water-retaining agent for plant crops with little or no environmental impact, and / or - water retaining material for plant crops and a water retainer for plant crops with fertilizing properties. Description of the invention

[0014] For this purpose, a water-retaining material for plant crops, called a retainer, is proposed according to a first alternative of the invention.

[0015] The retainer comprises or is made up, by weight or mass percentage, of dry matter, between 90 and 100% of at least one partially acetylated polysaccharide, referred to as at least one polysaccharide.

[0016] The at least one polysaccharide, preferably each of the polysaccharides among the at least one polysaccharide, comprises, by dry weight, between 6 and 18% acetyl groups.

[0017] The retainer also includes between 0 and 10% of adjuvant(s).

[0018] The adjuvant(s) include one or more fertilizers and / or one or more mycorrhizae and / or one or more rhizobia.

[0019] Preferably, the retainer comprises or is made up, by weight or mass percentage, of dry matter, between 90 and 100% of a polysaccharide, preferably of a single polysaccharide.

[0020] Preferably, at least one polysaccharide is a branched or branched polysaccharide.

[0021] Preferably, at least one polysaccharide, preferably each of the polysaccharides among the at least one polysaccharide, comprises, by weight of dry matter, acetyl groups, at a mass percentage: - greater than or equal to 6%, preferably 7%, preferably 8%, advantageously 9%, and particularly advantageously greater than or equal to 10%, and / or - less than or equal to 18%, preferably 17%, preferably 16%, advantageously 15%, and particularly advantageously less than or equal to 14%.

[0022] It can be understood by "acetylated polysaccharide": a polysaccharide comprising acetyl groups (CH3-CO)- linked to atoms or groups of monomers forming, at least in part, preferably constituting, the polysaccharide.

[0023] It can be understood as "partially acetylated polysaccharide": a polysaccharide in which only some of the atoms or groups of the monomers forming, at least in part, preferably constituting, the polysaccharide are linked to acetyl groups.

[0024] By way of non-limiting examples, it can be understood by "monomer of a polysaccharide": monosaccharides (or sugars) or derivatives (such as, for example, uronic acids).

[0025] Preferably the retention agent comprises or is composed, in dry matter, of at least one polysaccharide, at a mass percentage: - greater than or equal to 90%, preferably 91%, preferably 92%, advantageously 93%, particularly advantageously 94%, very particularly advantageously 95%, preferably 96%, even more preferably 97%, most preferably 98%, even more preferably greater than or equal to 99%, and most preferably equal to 100%, and / or - less than or equal to 100%, preferably still 99, advantageously 98, particularly advantageously 97, very particularly advantageously 96, preferably 95, even more preferably 94, even more preferably 93, even more preferably greater than or equal to 91 and most preferably less than or equal to 90%.

[0026] Preferably, the mass percentage, by weight of dry matter of said retainer, of adjuvant(s) complements the mass percentage, by weight of dry matter of said retainer, of said at least one polysaccharide so that the sum of the mass percentages of said at least one polysaccharide and of the adjuvant(s) constitutes between 95 and 100% of the weight, by dry matter, of said retainer.

[0027] Preferably, the retention agent comprises, on a dry matter basis, one or more additives, at a mass percentage: - less than or equal to 10%, preferably 9, preferably 8, advantageously 7, particularly advantageously 6, most advantageously 5, preferably 4, even more preferably 3, even more preferably 2, even more preferably 1, and preferably equal to 0%, and / or - greater than or equal to 0%, preferably to 1, preferably still to 2, advantageously to 3, particularly advantageously to 4, very particularly advantageously to 5, preferably to 6, even more preferably to 7, even more preferably to 8, even more preferably to 9 and most preferably greater than or equal to 10%.

[0028] The retainer may not include any adjuvant(s).

[0029] Preferably, at least one polysaccharide, preferably each of the polysaccharides among the at least one polysaccharide, comprises or is composed of, as residues, constituents, units or motifs, by dry weight: - 25 and 50% of uronic acid(s), - 8 and 32% galactose, and - 10 and 35% of rhamnose.

[0030] It can be understood by "residue": constituent, unit or motif.

[0031] Preferably, the uronic acid residue(s) comprise or are composed of glucuronic acid and glucuronic acid.

[0032] Preferably, at least one polysaccharide may comprise between 15 and 45% galacturonic acid and between 2 and 45% glucuronic acid.

[0033] Preferably, the sum, by weight of dry matter, of the residues of uronic acid, galacturonic acid and glucuronic acid is between 25 and 48%.

[0034] Preferably, at least one polysaccharide, preferably each of the polysaccharides among the at least one polysaccharide, comprises or is composed of, as residues: - of uronic acid(s), by weight of dry matter, at a percentage greater than or equal to 25% or more, preferably at 26, preferably even more at 27, advantageously at 28, particularly advantageously at 29, most advantageously at 30, preferably at 31, even more preferably at 32, even more preferably at 33, even more preferably at 34 and most preferably greater than or equal to 35%, and / or - of uronic acid(s), by weight of dry matter, at a percentage less than or equal to 50%, preferably at 49, preferably still at 48, advantageously at 47, particularly advantageously at 46, most advantageously at 45, preferably at 44, even more preferably at 43, even more preferably at 42, even more preferably at 41 and preferably of all less than or equal to 40%, and / or - of galactose, by weight of dry matter, at a percentage less than or equal to 32%, preferably at 31%, preferably even more at 30%, advantageously at 29%, particularly advantageously at 28%, most advantageously at 27%, preferably at 26%, even more preferably at 25%, most preferably at 24%, even more preferably at 23%, and / or - of galactose, by weight of dry matter, at a percentage greater than or equal to 8%, preferably at 9%, preferably even more at 10%, advantageously at 11%, particularly advantageously at 12%, most advantageously at 13%, preferably at 14%, even more preferably at 15%, most preferably at 16%, even more preferably at 17%, and preferably above all greater than or equal to 18%, and / or - of rhamnose, by weight of dry matter, at a percentage greater than or equal to 10%, preferably at 11, preferably still at 12, advantageously at 13, particularly advantageously at 14, most advantageously at 15, preferably at 16, even more preferably at 17, most preferably at 18, even more preferably at 19 and most preferably greater than or equal to 20%, and / or - of rhamnose, by weight of dry matter, at a percentage less than or equal to 35%, preferably at 34, preferably still at 33, advantageously at 32, particularly advantageously at 31, very particularly advantageously at 30, preferably at 29, even more preferably at 28, more preferably at 27, even more preferably at 26 and most preferably less than or equal to 25%.

[0035] Preferably, the sum of the mass percentages of the residues of uronic acid(s), galactose and rhamnose, of which at least one polysaccharide is, by weight of dry matter, greater than or equal to 95% and less than or equal to 100%.

[0036] Preferably, the sum of the mass percentages of the residues of uronic acid(s), galactose and rhamnose, being, by weight of dry matter of said at least one polysaccharide, is: - greater than or equal to 95%, preferably 96%, preferably 97%, advantageously 98%, particularly advantageously 99%, and especially advantageously equal to 100%, and / or - less than or equal to 100%, preferably 99%, preferably 98%, advantageously 97%, particularly advantageously 96%, and very particularly advantageously less than or equal to 95%.

[0037] Preferably, the residues, constituents, units or motifs can be obtained, in particular in isolation, by hydrolysis of at least one polysaccharide.

[0038] Preferably, the residues, constituents, units or motifs of at least one polysaccharide can be obtained, in particular in isolation, by hydrolysis.

[0039] Preferably, the residues are monosaccharides (or sugars) or derivatives (such as, for example, uronic acids).

[0040] Hydrolysis can be understood to mean: hydrolysis in an aqueous medium, for example acid hydrolysis, and / or enzymatic hydrolysis. In particular, the residues can be obtained by aqueous hydrolysis of all or part of the glycosidic bonds (between the residues) of at least one polysaccharide.

[0041] Preferably, at least one polysaccharide has a molecular mass between 5.10 6 and 21.10 6Daltons.

[0042] Preferably, at least one polysaccharide has a molecular mass of: - greater than or equal to 5.10 6 Daltons, preferably at 6.10 6 preferably still at 7.10 6 advantageously at 8.10 6 and in a particularly advantageous manner greater than or equal to 9.10 6 , and / or - less than or equal to 20.10 6 Daltons, preferably at 19.10 6 preferably still at 18.10 6 advantageously at 17.10 6 and in a particularly advantageous manner, less than or equal to 16.10 6 .

[0043] Preferably, after swelling, at a mass swelling rate greater than 50, at least 60%, by weight, of the retainer, preferably of at least one polysaccharide, the retainer is hydrolyzed in 120 days or after a period of six months from the hydration (i.e., the swelling).

[0044] Preferably, the retainer, in particular at least one polysaccharide, is hydrolyzed, in 120 days or more, to 80% or more, by weight, after swelling to a mass swelling rate greater than or equal to 50%, preferably to 60, preferably even more to 70, advantageously to 80, particularly advantageously to 90, most advantageously to 100, preferably to 110, even more preferably to 120, most preferably to 130, even more preferably to 140 and most preferably equal to or greater than 150%.

[0045] Preferably, the retainer, in particular at least one polysaccharide, after swelling to a mass swelling rate greater than or equal to 50, is hydrolyzed, after 120 days or more, to 60% or more, by weight, preferably to 62, preferably even more to 64, advantageously to 66, particularly advantageously to 68, particularly advantageously to 70, preferably to 72, even more preferably to 74, even more preferably to 76, even more preferably to 78 and most preferably to 80% or more, by weight.

[0046] Optimally, the retainer, in particular at least one polysaccharide, after swelling to a mass swelling rate greater than or equal to 50, is hydrolyzed, after 120 days or more, to 81% or more, by weight, preferably to 82, preferably still to 83, advantageously to 84, particularly advantageously to 85, most advantageously to 87, preferably to 91, even more preferably to 93, more preferably to 95, even more preferably to 97 and most preferably to 99% or more, by weight.

[0047] Preferably, the retainer, in particular at least one polysaccharide, after swelling to a mass swelling rate greater than or equal to 50, is hydrolyzed to 80% or more, by weight, in 120 days or more, preferably in 130, preferably even more in 140, advantageously in 145, in a manner particularly advantageous in 150, very particularly advantageous in 155, preferably in 160, even more preferably in 165, even more preferably in 170, even more preferably in 175 and most preferably in 180 days or more.

[0048] Preferably, at least one polysaccharide is Karaya gum.

[0049] Preferably, Karaya gum comprises, preferably, is made up of a single polysaccharide.

[0050] Preferably, the retainer comprises or is made up, by weight or mass percentage, of dry matter, between 90 and 100% of a single polysaccharide being Karaya gum.

[0051] Preferably, at least one polysaccharide and / or Karaya gum is one or more gums extracted, respectively, from one or more plants of the Sterculiaceae family and / or the Bixaceae family.

[0052] Preferably, at least one polysaccharide according to the invention is a natural product obtained from a plant.

[0053] Preferably, at least one polysaccharide according to the invention is a natural product obtained from the Sterculiaceae family.

[0054] Preferably, at least one polysaccharide according to the invention is a natural product obtained from the Bixaceae family. Preferably, at least one polysaccharide according to the invention is a natural product obtained from the genus Sterculia of the Sterculiaceae family and / or from the genus Cochlospermum of the Bixaceae family.

[0055] The at least one polysaccharide may be a mixture, for example a mixture of a single polysaccharide, obtained partly from the Bixaceae family and partly from the Sterculiaceae family.

[0056] Preferably, the fertilizer(s) include or are mineral fertilizers based on, or comprising, nitrogen and / or phosphorus and / or potassium.

[0057] The term "mineral fertilizers" can be understood to mean mineral fertilizers or NPK fertilizers.

[0058] According to the invention, a water-retaining agent is also proposed.

[0059] Preferably, according to a first aspect of the water-retainer, the water-retainer is a granular water-retainer.

[0060] Preferably, the granular water-retaining agent consists of grains with a size between 20 and 2000 pm.

[0061] Preferably, the grains of the granular water-retaining agent are made of the water-retaining material for plant crops according to the invention.

[0062] Preferably, the grain size is greater than or equal to 20 pm, preferably greater than or equal to 20 pm, preferably even greater than or equal to 25 pm, advantageously greater than or equal to 30 pm, particularly advantageously greater than or equal to 35 pm, particularly advantageously greater than or equal to 40 pm, preferably greater than or equal to 42 pm, even more preferably greater than or equal to 44 pm, even more preferably greater than or equal to 46 pm, even more preferably greater than or equal to 48 pm and most preferably greater than or equal to 50 pm.

[0063] Preferably, according to a second aspect of the water-retainer, the water-retainer is a bead-type water-retainer.

[0064] Preferably, water-retaining agent, water-retaining bead-type ...

[0065] Preferably, the beads of the water-retaining bead are made of the water-retaining material for plant crops according to the invention.

[0066] Preferably, the size of the balls is equal to or strictly greater than 2 mm, preferably greater than or equal to 2.1 mm, preferably even greater than or equal to 2.2 mm, advantageously greater than or equal to 2.3 mm, particularly advantageously greater than or equal to 2.4 mm, particularly advantageously greater than or equal to 2.5 mm, preferably greater than or equal to 2.6 mm, even more preferably greater than or equal to 2.7 mm, even more preferably greater than or equal to 2.8 mm, even more preferably greater than or equal to 2.9 mm and most preferably greater than or equal to 3 mm.

[0067] Preferably, according to a third aspect of the water-retaining agent, the water-retaining agent is a gel-based water-retaining agent.

[0068] Preferably, according to the third aspect of the water-retaining agent, the gel water-retaining agent consists of a hydrogel comprising, by weight or mass percentage, of the dry matter of said gel water-retaining agent, or of the hydrogel: - between 99.6 and 90% water, and, respectively - between 0.4 and 10% of the water-retaining material for plant crops according to the invention.

[0069] Preferably, the water-retaining gel, or hydrogel, comprises or is composed of: - a water mass percentage less than or equal to 99.6%, preferably 99%, preferably 98.5%, advantageously 98%, particularly advantageously 97%, most advantageously 96%, preferably 95%, most preferably 94%, most preferably 93%, most preferably 92%, most preferably less than or equal to 91%, and most preferably less than or equal to 90%, and / or - a mass percentage of water-retaining material for plant crops according to the invention greater than or equal to 0.4%, preferably 0.7%, preferably still 1%, advantageously 2%, particularly advantageously 3%, most advantageously 4%, preferably 5%, even more preferably 6%, most preferably 7%, even more preferably 8%, most preferably greater than or equal to 9%, and most preferably greater than or equal to 10%.

[0070] Preferably, the water-retaining material for plant crops according to the invention is suitable, more preferably is particularly adapted, even more preferably is designed, and particularly advantageously constitutes the water-retaining agent according to the invention. Furthermore, any characteristic of the water-retaining material for plant crops according to the invention is directly transferable to the water-retaining agent according to the invention. Brief description of the FIGURES

[0071] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which: - FIGURE 1 is a graph illustrating the growth of bean shoots over thirty days, in universal potting soil, with a water-retaining agent according to the invention or with a polyacrylate water-retaining agent according to the state of the art and without a water-retaining agent, - FIGURE 2 is a histogram illustrating the percentage of water content, after 30 days without watering, in the soil substrate of bean seedlings in a pot containing only universal potting soil and in the soil substrate of bean seedlings in a pot containing universal potting soil and a water-retaining agent according to the invention, - FIGURE 3 is a histogram illustrating the percentage of water contained, after 30 days without watering, in bean shoots planted in a pot containing only universal potting soil and in bean shoots planted in a pot containing universal potting soil and the water-retaining agent according to the invention, - FIGURE 4 is a histogram illustrating the number of leaves per shoot planted in a pot containing only universal potting soil and the number of leaves per shoot (or plant) planted in a pot containing universal potting soil and the water-retaining agent according to the invention, - FIGURE 5 is a histogram illustrating the weighted root mass, after 30 days without watering, before and after drying of the root system, of shoots planted in a pot containing only universal potting soil and of shoots planted in a pot containing universal potting soil and the water-retaining agent according to the invention.

[0072] In the figures and in the rest of the description, elements common to several figures retain the same reference. Description of a method of implementation

[0073] The embodiments described below are in no way limiting; variants of the invention may include, in particular, a selection of the described features, isolated from the other described features (even if this selection is isolated within a sentence containing these other features), if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one feature, preferably functional, without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0074] A water-retaining material for plant crops, referred to as a retainer, according to the invention, is described.

[0075] The retainer comprises, by dry weight, between 90 and 100% of at least one partially acetylated polysaccharide, referred to as at least one polysaccharide.

[0076] At least one polysaccharide comprises, by dry weight, between 6 and 18% acetyl groups.

[0077] The at least one polysaccharide also includes, as residues, by dry weight: - 25 and 50% of uronic acid(s), - 8 and 32% galactose, and - 10 and 35% of rhamnose.

[0078] By way of example, according to a first non-limiting embodiment presented, at least one polysaccharide is a natural product.

[0079] In particular, at least one polysaccharide is obtained from a plant.

[0080] According to the first non-limiting embodiment presented, the at least one polysaccharide is one or more gums extracted, respectively, from one or more plant(s) of the family Sterculiaceae.

[0081] According to the first embodiment, at least one polysaccharide is Karaya gum.

[0082] According to the first embodiment, the retainer comprises, by dry weight, between 95 and 100% of at least one polysaccharide.

[0083] Thus, according to the first embodiment, the retainer comprises only Karaya gum.

[0084] The composition of Karaya gum, that is to say, at least one polysaccharide according to the first embodiment, may include other additional residues in small quantities, typically less than 5%. Among the additional residues contained in small quantities, particularly other sugars, Karaya gum may include, in particular, glucose, xylose, or ribose.

[0085] In addition to the variability in intra-species composition of at least one polysaccharide described in the previous paragraph, the rate of additional residues, as well as the number and type of additional residues, vary depending on the particular plant (of the Sterculiaceae family) from which Karaya gum is taken.

[0086] In addition, the composition of Karaya gum, and therefore that of at least one polysaccharide, varies depending on the time of year, the place of cultivation and the particular species from which the Karaya gum is taken.

[0087] Finally, the collected karaya gum may contain substances other than gum, such as, for example, plant debris (particularly from the plant or environment where the gum is collected) and / or traces of materials from the tools used to collect the gum, and / or traces of the containers used to transport the gum and / or traces of the tools used to shape the water-retaining agent from the karaya gum.

[0088] For all these reasons, the composition of Karaya gum and therefore the composition of the at least polysaccharide, and therefore of the water-retaining material and / or the hydro-retainer according to the first embodiment, cannot be defined to 100%.

[0089] A first embodiment of a granular water-retaining agent composed of grains with a size between 20 and 2000 pm is described.

[0090] The grains are made up of the water-retaining material for plant crops according to the first embodiment of the retainer.

[0091] According to the first embodiment of the water-retainer, the grains have a size of 1 pm ± 0.2 pm.

[0092] Granular water-retaining agent is suitable for most "common" plant crops, whether in open ground, in planters or in pots.

[0093] In an initial experiment on the first embodiment of the water-retaining agent, 6.0 g ± 0.1 g of Karaya gum were immersed in 600 ml of water. After 24 hours, the water-swollen gum was recovered by filtration through a 250 µm mesh sieve and then weighed. The experiment was repeated three times. Water absorption was measured to be between 50 and 150 times the mass of Karaya gum used.

[0094] In a second experiment focusing on the first embodiment of the water-retaining agent, the growth of bean seedlings, plants, or plants was monitored. Eight bean seedlings were planted in three separate pots. The first pot, designated pot 1, contained only universal potting soil; another pot, designated pot 2, contained universal potting soil and 4 grams of the water-retaining agent according to the first embodiment of the water-retaining agent; and the last pot, designated pot 3, contained universal potting soil and 4 grams of polyacrylate.

[0095] Each pot was watered with 400 ml of water on the first day. No further watering was given to the seedlings. The eight pots were kept at 22°C with an air humidity between 40 and 60% and are subjected to natural sunlight. The results are presented in FIGURES 1 to 4.

[0096] It has been observed that after initial swelling, the retainer, i.e. Karaya gum, and consequently the water retainer according to the invention, hydrolyzes very rapidly compared to state-of-the-art retainers based on synthetic polyacrylamides.

[0097] While state-of-the-art synthetic polymer-based water retainers maintain their retention capacity for 3 to 5 years after their initial swelling, the retainer, particularly Karaya gum, and consequently the water-retaining agent according to the invention, retains its water retention capacity for 4 to 6 months. Indeed, after swelling at a mass swelling rate exceeding 50%, at least 80% by weight, the retainer, particularly Karaya gum, and consequently the water-retaining agent, is hydrolyzed within 120 days.

[0098] Thus, the use of the retainer, i.e. Karaya gum, and consequently of the water retainer according to the invention would have been counterintuitive for a person skilled in the art.

[0099] Curve 1 of FIGURE 1 represents the evolution in size of the stems of the shoots planted in pot 1 (containing the water-retaining agent according to the first embodiment), curve 2 of FIGURE 1 represents the evolution in size of the stems of the shoots planted in pot 2 (containing only universal potting soil) and curve 13 of FIGURE 1 represents the evolution in size of the stems of the shoots planted in pot 3 (containing polyacrylate).

[0100] Figure 1 shows that shoot growth (in other words, stem growth) is similar for curves 1 and 2 up to the 22nd. eme day. This effect is due to the fact that certain components of the potting soil (especially humus) retain water. Conversely, the growth of shoots in pot 13 is significantly less than that of shoots in pots 1 and 2 between the 10 eme and the 25th emeday. This observation could indicate an adverse effect of polyacrylate on plant growth.

[0101] Referring to FIGURE 1, the size of the shoots in pot 3 catches up to that of the shoots in pot 2 at 30 eme day, but remains smaller than the size of the shoots in pot 1. The size of the shoots in pot 1 is greater than the size of the shoots in pots 2 and 3 throughout the experiment. This effect will be studied in Figures 3 and 4.

[0102] With further reference to FIGURE 1, we observe from the 22nd emeA clear difference was observed between the growth of shoots in a substrate containing a water-retaining agent according to the first embodiment (pot 1) and shoots in a substrate without such an agent (pot 2). It was noted that shoot growth was halted in pot 2, which did not contain a water-retaining agent, while shoot growth in the pots containing a water-retaining agent (pots 1 and 3) was maintained due to the prolonged water supply provided by the agents.

[0103] FIGURE 2 illustrates the quantity of water, by mass of dry matter, contained at 30 eme day, in the universal potting soil (stick referenced 3 on FIGURE 2) from pots 2 (comprising only the universal potting soil) and in the universal potting soil from pots 1 (comprising the universal potting soil and the water retainer according to the first embodiment) (stick referenced 4 on FIGURE 2).

[0104] FIGURE 3 illustrates the quantity of water, by mass of dry matter, contained at 30 eme day, in the bean shoots from pots 2 (containing only universal potting soil) on the stick referenced 5 in FIGURE 3 and the quantity of water, by mass, contained in the bean shoots from pots 1 (containing universal potting soil and water retainer according to the first embodiment) on the stick referenced 6 in FIGURE 3.

[0105] Figures 2 and 3 confirm the observations made on Figure 1. The water-retaining agent according to the invention provides the plant with a significantly prolonged supply of water in terms of both duration and quantity.

[0106] The results in FIGURES 2 and 3 highlight the effect of the water-retaining agent on the vegetative apparatus of bean shoots.

[0107] Figure 4 illustrates the number of leaves per plant, counted at 22 emeday, on the bean shoots from pot 2 containing only universal potting soil (stick referenced 7 in FIGURE 4). and on the bean shoots from pot 2 containing universal potting soil and 4 g of water-retaining agent according to the first embodiment (stick referenced 8 in FIGURE 3).

[0108] At 22 eme day, as seen in FIGURE 1, the wilting point has not yet been reached (whether for the shoots planted in pot 2 (containing only universal potting soil) (curve 2 of FIGURE 1) or for the shoots planted in pot 1 (containing universal potting soil and water retainer according to the first embodiment) (curve 1 of FIGURE 1).

[0109] Thus, unexpectedly and surprisingly, the difference in growth (in number of leaves) observed in FIGURE 4 demonstrates a fertilizing effect of the retainer, in particular of Karaya gum, and consequently of the water retainer according to the first embodiment.

[0110] Indeed, FIGURE 4 demonstrates the intrinsic or self-fertilizing effect (i.e. in the absence of adjuvant(s)) of the retainer, in particular Karaya gum, and consequently of the water-retainer according to the first embodiment. [YES] Therefore, in addition to providing a water retention effect, the retainer according to the invention provides a fertilizing effect. The two combined effects offer a synergy combining prolonged water supply (water retention) and crop fertilization.

[0112] Further results demonstrated the fertilizing effect of the water-retaining agent according to the invention. These results relate to a comparative study of the leaf epidermis (callose) of seedlings planted in pot 2 containing only universal potting soil (curve 2 of FIGURE 1) and seedlings planted in pot 1 containing universal potting soil and the water-retaining agent according to the first embodiment (curve 1 of FIGURE 1). These results confirm the effect observed in FIGURE 3 by the colorimetric observation of the presence of hydrolysates (i.e., that is to say residues of sugars (monomers) from the hydrolysis of at least one polysaccharide) in the epidermis of shoots from pot 1 containing universal potting soil and water retainer according to the first embodiment (i.e. the retainer, in particular Karaya gum).

[0113] Additional results relating to the analysis of the root system were also obtained according to the second experiment.

[0114] Observation of the root system showed that the secondary roots of the shoots from pot 1 containing universal potting soil and water-retaining material according to the first embodiment are oriented towards the grains of water-retaining material.

[0115] At the 30 emeOn day 9, the mass of the root system of bean seedlings from pot 2 (containing only universal potting soil) was compared to the mass of the root system of bean seedlings from pot 1 (containing universal potting soil and the water-retaining agent according to the first embodiment) before and after drying. The masses, in grams, are shown in Figure 5. It can be seen that the root system of the seedlings planted in the presence of the water-retaining agent is much more developed. It is twice as developed as the root system of the seedlings planted in pots containing only potting soil. This demonstrates the beneficial effect of the water-retaining agent on plant growth and thus the additional fertilizing effect provided by the agent according to the first embodiment.

[0116] A bead-based water-retaining agent is also proposed. This bead-based water-retaining agent consists of a collection of beads, larger than 2 mm, forming the retaining agent according to the first embodiment. The beads are typically between 2 and 5 mm in size.

[0117] According to a non-limiting example, the balls are obtained by compression, for example by means of a press, typically at a pressure of between 4 and 10 tonnes, of the retainer according to the first embodiment.

[0118] The water-retaining bead is particularly suitable for applications involving preserving cut flowers. The hydrated beads are placed in contact, for example in a vase, with the cut stem ends of the flowers to be preserved.

[0119] A gel-based water-retaining agent is also available. This gel-based water-retaining agent consists of a hydrogel. The hydrogel comprises, by weight, between 99.6% and 90% water, and, respectively, between 0.4% and 10% of the water-retaining agent, depending on the specific embodiment.

[0120] Water-retaining gel is particularly suitable for container gardening (pots, planters, basins, etc.). The gel is deposited at the level of the plant's roots.

[0121] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

[0122] In particular, all the variants and embodiments described can be combined with each other if there are no technical obstacles to this combination.

[0123] Thus, in combinable variants of the previously described embodiments: - at least one polysaccharide has a molecular mass between 5.10 6 and 20.10 6 Daltons, and / or - the retainer according to the first embodiment comprises a single polysaccharide, i.e., only Karaya gum, and / or - the sum of the mass percentages of the residues of uronic acid(s), galactose and rhamnose, by weight of dry matter of said at least one polysaccharide, is greater than or equal to 95% and less than or equal to 100%, and / or - at least one polysaccharide, in particular the polysaccharide according to the first embodiment, comprises: • residues of galacturonic acid and rhamnose, linked by a glycosidic or polysaccharide bond, forming the main chain of at least one polysaccharide, and / or • galactose residues, forming a side chain of at least one polysaccharide, linked by a glycosidic or ossicular bond to a part, for example half, of the rhamnose residues of the main chain of at least one polysaccharide, and / or • galactose residues, forming a side chain of at least one polysaccharide, linked by a glycosidic or ossidic bond to a portion of the galacturonic acid residues of the main chain of at least one polysaccharide, and / or • glucuronic acid residues, forming a side chain of at least one polysaccharide, linked by a glycosidic or ossicular bond to a portion of the galacturonic acid residues of the main chain of at least one polysaccharide, and / or - according to one variant, at least one polysaccharide is a synthetic product, and / or - according to one variant, at least one polysaccharide is obtained by synthesis, for example from uronic acid(s), galactose, and rhamnose, and / or - according to the first embodiment, at least one polysaccharide and / or Karaya gum is one or more gums extracted, respectively, from one or more plants of the Bixaceae family, and / or - according to a second embodiment, the retainer further comprises between 0 and 10% of adjuvant(s); the adjuvant(s) comprise one or more fertilizers and / or one or more mycorrhizae and / or one or more rhizobia, and / or - according to the second embodiment, the mass percentage, by weight of dry matter of said retainer, of adjuvant(s) completes the mass percentage, by weight of dry matter of said retainer, of said at least one polysaccharide so that the sum of the mass percentages of said at least one polysaccharide and of the adjuvant(s) constitutes between 95 and 100% of the weight, by dry matter, of said retainer.

Claims

DEMANDS 1. Water-retaining material for plant crops, called a water-retaining agent, comprising, by weight of dry matter: - between 90 and 100% of at least one partially acetylated polysaccharide, referred to as at least one polysaccharide; said at least one polysaccharide comprises, by weight of dry matter, between 6 and 18% acetyl groups, - between 0 and 10% of adjuvant(s); the adjuvant(s) include one or more fertilizers and / or one or more mycorrhizae and / or one or more rhizobia, the mass percentage, by weight of dry matter of said retainer, of adjuvant(s) completes the mass percentage, by weight of dry matter of said retainer, of said at least one polysaccharide so that the sum of the mass percentages of said at least one polysaccharide and of the adjuvant(s) constitutes between 95 and 100% of the weight, by dry matter, of said retainer.

2. Retainer according to claim 1, wherein said at least one polysaccharide comprises, as residues, by dry weight: - 25 and 50% of uronic acid(s), - 8 and 32% galactose, and - 10 and 35% rhamnose; the sum of the mass percentages of uronic acid(s), galactose and rhamnose being, by weight of dry matter of said at least one polysaccharide, greater than or equal to 95% and less than or equal to 100%.

3. Retainer according to claim 1 or 2, wherein at least one polysaccharide has a molecular mass between 5.10 6 and 20.10 6 Daltons.

4. Retainer according to any one of the preceding claims, wherein, after swelling to a mass swelling rate greater than 50, at least 60%, by weight, of the retainer, said retainer is hydrolyzed in 120 days.

5. Retainer according to any one of the preceding claims, wherein at least one polysaccharide is Karaya gum.

6. Retainer according to any one of claims 1 to 4, wherein at least one polysaccharide is one or more gums extracted, respectively, from one or more plants of the family Sterculiaceae and / or from one or more plants of the family Bixaceae.

7. Retainer according to any one of the preceding claims, wherein the fertilizer(s) are mineral fertilizers based on nitrogen and / or phosphorus and / or potassium.

8. Granular water retainer, consisting of grains having a size between 20 and 2000 µm, said grains being made of the water retainer material for plant crops according to any one of claims 1 to 7.

9. Water-retaining bead, consisting of a set of beads having a size greater than 2 mm, said beads being made of the water-retaining material for plant crops according to any one of claims 1 to 7.

10. Water-retaining gel, consisting of a hydrogel comprising, by weight of dry matter of said water-retaining gel: - between 99.6 and 90% water, and, respectively - between 0.4 and 10% of the water-retaining material for plant crops according to one of claims 1 to 7.

Images