Granulated seeds

Abstract

The invention relates to a process for the production of granulated seed comprising seed kernels which are coated with a coating layer, the process comprising the following steps: providing seed kernels, applying a binder to the seed kernels, giving rise to seed kernels coated with a binder, and applying a coating composition comprising silica to the seed kernels coated with binder, giving rise to seed kernels coated with a coating layer. The invention furthermore relates to the use of silica as component of the coating layer of granulated seed for improving the germination ability of the seed. The invention furthermore relates to granulated seed, comprising seed kernels coated with a coating layer, characterized in that the coating layer comprises silica and that the silica is distributed within the entire coating layer.

Claims

1. A granulated seed, comprising: a seed, which is not a seed of tomato, cucumber, carrot, spinach, onion, or sugarbeet; and a coating layer coating the seed, wherein the coating layer comprises: (i) at least one non-silica inorganic or organic filler; (ii) silica in an amount of 10% to 70% by weight based on a weight of the coating layer and in an amount of 20% to 55.3% by weight based on a weight of the seed; and (iii) a binder, wherein the silica has a surface area ranging from 20 to 190 m.sup.2/g and is uniformly distributed in the coating layer, and wherein the granulated seed exhibits at least 80.25% of germination ability when stored at 20° C. for three days on a paper moistened with water.

2. The granulated seed of claim 1, wherein the coating layer comprises the silica in an amount ranging from 20% to 45% based on the weight of the coating layer.

3. The granulated seed of claim 1, wherein a difference between an amount of the silica in an inner part of the coating layer and an amount of the silica in an outer part of the coating layer is not more than 50% by weight; wherein the inner part is a part of the coating layer lying directly on the seed to enclose the seed when the coating layer is divided into two equally thick shells, and the outer part is a remaining part of the coating layer lying outside the inner part to enclose the inner part.

4. The granulated seed of claim 1, wherein a difference between an amount of the silica in an inner part of the coating layer and an amount of the silica in an outer part of the coating layer is not more than 15% by weight; wherein the inner part is a part of the coating layer lying directly on the seed to enclose the seed when the coating layer is divided into two equally thick shells, and the outer part is a remaining part of the coating layer lying outside the inner part to enclose the inner part.

5. The granulated seed of claim 1, wherein the silica is precipitated or pyrogenic silica that has a pore maximum ranging from 30 to 60 nm.

6. The granulated seed of claim 1, wherein the silica is precipitated or pyrogenic silica that has the surface area ranging from 50 to 190 m.sup.2/g and a pore maximum ranging from 35 to 50 nm.

7. The granulated seed of claim 1, wherein the at least one non-silica inorganic or organic filler comprises a mixture of cellulose, lignin, and hemicellulose.

8. The granulated seed of claim 1, wherein the binder is selected from the group consisting of at least one polyvinyl alcohol, a polycarboxylate, a polyacrylic acid, a polysaccharide, a cellulose, a carboxymethylcellulose, an acrylic dispersion, a polymethacrylate, a polyvinyl acetate, a polyethylene oxide, an alkyl acrylate, a gelatin, a starch, an alginate, a casein, a molasses, a pectin and a mixture thereof.

9. The granulated seed of claim 1, wherein the binder comprises polyvinyl alcohol.

10. The granulated seed of claim 1, wherein the coating layer further comprises a hygroscopic salt in an amount ranging from 0.1% to 15% by weight of the coating layer.

11. The granulated seed of claim 1, wherein the seed is 0.3 mm to 10 mm in size.

12. The granulated seed of claim 1, wherein the seed is rapeseed having a size ranging from 2.0 to 3.6 mm.

13. The granulated seed of claim 1, consisting of the seed and the coating layer.

14. The granulated seed of claim 1, wherein the seed is a seed of Brassicaceae, Legumes, Leguminosae, catch crops, cereals, ornamentals or tobacco.

15. The granulated seed of claim 1, wherein the seed is a seed of Brassicaceae.

16. A method for improving germination of a granulated seed, comprising: coating a seed with a composition comprising at least one non-silica inorganic or organic filler, silica, and a binder, thereby forming a coating layer coating the seed, wherein the seed is not a seed of tomato, cucumber, carrot, spinach, onion, or sugarbeet, wherein the silica is in an amount of 10% to 70% by weight based on a weight of the coating layer and in an amount of 20% to 55.3% by weight based on a weight of the seed, wherein the silica has a surface area ranging from 20 to 190 m.sup.2/g and is uniformly distributed in the coating layer, and wherein the seed coated by the coating layer exhibits at least 80.25% of germination ability when stored at 20° C. for three days on a paper moistened with water.

17. A method for making a coated seed, comprising: mixing a seed with a coating composition comprising: (i) at least one non-silica inorganic or organic filler; (ii) silica; and (iii) at least one liquid binder, such that the seed is coated by a coating layer, wherein the silica is in an amount of 10% to 70% by weight based on a weight of the coating layer and in an amount of 20% to 55.3% by weight based on a weight of the seed, wherein the seed is not a seed of tomato, cucumber, carrot, spinach, onion, or sugarbeet, wherein the silica has a surface area ranging from 20 to 190 m.sup.2/g and is uniformly distributed in the coating layer, and wherein the coated seed exhibits at least 80.25% of germination ability when stored at 20° C. for three days on a paper moistened with water.

18. The method of claim 17, further comprising: separating and recovering the coated seed that is within 1.5-fold to 2.5-fold a mean seed size.

19. The method of claim 17, wherein the seed is rapeseed having a size ranging from 2.0 to 3.6 mm.

Description

(1) FIG. 1 shows a material-contrast electron micrograph of a seed in accordance with Example 1.

(2) FIG. 2 shows the silicon distribution, determined by EDX, in the seed shown in FIG. 1.

(3) FIG. 3 shows a material-contrast electron micrograph of a seed according to Example 7.

(4) FIG. 4 shows the silicon distribution, determined by EDX, in the seed shown in FIG. 3.

(5) FIG. 5 shows the REM/EDX micrograph of Example 1 in which the coating layer is divided into two coating-layer zones.

EXAMPLES

(6) The silicas employed in the examples hereinbelow have the physico-chemical properties shown in Table 1.

(7) TABLE-US-00002 TABLE 1 Physico-chemical properties of the silicas employed. d50 particle BET surface size .sup.[*.sup.] Pore maximum Product [m.sup.2/g] [μm] [nm] SIPERNAT ® 22 190 110 43 SIPERNAT ® 350 50 40 50 SIPERNAT ® 360 50 18 48 AEROPERL ® 300/30 300 33 37.5 .sup.[*.sup.] in accordance with ISO 13320-1

Example 1

(8) To produce granulated rapeseed, 300 g of rapeseed are introduced into a granulator (ERWEKA, Germany—composed of the drive unit AR403, universal coupling UG and the pelleting plate GTE, 300 mm diameter). The granulator consists of a revolving pan arranged at an angle of 45° C. and having a diameter of 30 cm and a rotation speed of 40 rpm. With the aid of a nozzle, the seed is sprayed with binder until seed kernels visibly agglomerate. The binder employed is an aqueous solution containing 5% by weight of Mowiol 28-99. Large agglomerates are carefully crushed by hand. Thereafter, coating composition is added. The coating composition employed is a mixture containing 30% by weight of SIPERNAT® 22 and 70% by weight of a basic coating composition. The basic coating composition employed is a mixture of 70% of Lignocel® (cellulose, lignin, hemicellulose) and 30% of Edasil® bentonite. Thereafter, more binder is sprayed on and coating composition is added. In total, 400 g of binder and 200 g of coating composition are added. The coated seed kernels which are being formed are fractionated through a screen of mesh size 3.35 mm and a further screen of 2.8 mm. The finely-particulate fraction is returned to the granulator. The fraction between 2.8 mm and 3.35 mm forms the desired product and is dried in a drying oven at a temperature of 40° C. The moisture content of the dried seed is determined in accordance with ISO 787-2 and is <8%.

Example 2

(9) Granulated seed in which the coating composition contains 70% by weight of SIPERNAT® 22 is prepared as described in Example 1. In total, 500 g of binder and 200 g of coating composition are employed.

Example 3

(10) Granulated seed in which the coating composition contains 30% by weight of SIPERNAT® 350 is prepared as described in Example 1. In total, 363 g of binder and 242 g of coating composition are employed.

Example 4

(11) Granulated seed in which the coating composition contains 30% by weight of SIPERNAT® 360 is prepared as described in Example 1. In total, 327 g of binder and 200 g of coating composition are employed.

Example 5

(12) Granulated seed in which the coating composition contains 70% by weight of AEROPERL® 300/30 is prepared as described in Example 1. In total, 502 g of binder and 237 g of coating composition are employed.

Example 6 (Comparative Example)

(13) Granulated seed in which the coating composition does not contain any silica is prepared as described in Example 1. In total, 301 g of binder and 250 g of coating composition are employed.

Example 7 (Comparative Example)

(14) Granulated seed was prepared as described in U.S. Pat. No. 6,156,699. To this end, 300 g of rapeseed were introduced into a granulator as described in Example 1 and sprayed with a mixture containing 2.7% by weight of polyvinyl alcohol Mowiol 28-99, 0.3% by weight of polysaccharide Elcema F150, 66% by weight of limestone Heladol 150, 0.5% by weight of surfactant Silipon RN 6031, 0.1% by weight of colorant Bayferrox 130, 0.1% by weight of dispersant Break Through DA 646 and 30.3% by weight of water. Thereafter, 10% by weight of SIPERNAT® 22, based on the weight of rapeseed and sprayed-on mixture, were applied and the mixture was granulated for 300 seconds. Thereafter, the product was dried.

Detection of the Silica Distribution in the Coating Layer

(15) To detect the silica distribution in the coating layer, the granules obtained in Examples 1 and 7 were subjected to a scanning-electron examination in connection with energy-dispersive X-ray analysis (EDX).

(16) The following instruments were used for this purpose: microscope from Jeol, type JSM-7600F, EDX system from Oxford Instruments INCA Energy 400 equipped with a PentaFETx3 SiLi detector (resolution 133 eV).

(17) The samples were embedded in an epoxy resin ground metallurgically, and electrical contact was made thereafter. The images were taken at an accelerating voltage of 20 KV and a working distance of 15 mm. The beam current of the primary electron beam was in the range of approximately 500 pA.

(18) Under these conditions, a representative zone of the sample was selected, and a material-contrast image of the sample section was first generated. This visualizes density differences within the sample, but a statement regarding the elements is as yet impossible. To this end, the zone was scanned by the EDX system over a period of 8 h (EDX mapping). The dead time amounted to approximately 30%. Elements of specific distribution images were generated from the spatially-resolved X-ray information obtained.

(19) The results of these tests are shown in FIGS. 1 to 4. FIG. 1 shows a material-contrast image of a seed according to Example 1. FIG. 2 shows the distribution of silicon in the same seed as determined by EDX. It can be seen clearly that the silicon is distributed across the entire thickness of the coating layer. FIG. 3 shows a material-contrast image of a seed according to Example 7. FIG. 4 shows the silicon distribution in the same seed as determined by EDX. It can be seen that the silicon is concentrated to a relatively thin layer on the surface of the coating layer compared to the overall thickness of the coating layer.

(20) These results demonstrate that, in a seed granulated in accordance with the invention, the silica is distributed within the entire coating layer, while this is not the case in a seed in accordance with U.S. Pat. No. 6,156,699.

(21) To test for the distribution of silica within the coating layer, the coating layer, which is discernible in the material-contrast image, is divided into an inner and outer shell. To this end, one will first define two straight lines g.sub.1 and g.sub.2, which connect in each case a point at the inner edge of the coating-layer area to the nearest point of the outer edge of the coating layer and which do not cross each other in the zone of the coating layer. The two points on the inner edge of the coating layer should be selected such that their distance amounts to at least 200 μm. Thereafter, the straight lines g.sub.1 and g.sub.2 are connected by a line l.sub.3, where line l.sub.3 extends such that, for each point of line l.sub.3, the distance to the nearest point at the inner edge on the coating layer equals the distance to the nearest point on the outer edge of the coating layer. The segment of the coating layer enclosed by the straight lines g.sub.1 and g.sub.2 is, therefore, divided by the line l.sub.3 into an inner zone and an outer zone. The mean silicon concentration within the two zones is determined with reference to the EDX image so as to obtain a measure for the mean silicon concentration in the inner and the outer shell of the coating layer.

(22) FIG. 5 shows the REM/EDX image of Example 1 in which the coating layer is divided into two coating-layer zones. To analyse the silicon of the silica, the silicon content of the bentonite in the two zones was subtracted from the total silicon concentrations of spectrum 1 and 2, respectively. Accordingly, spectrum 1 has a silica concentration of 24.8% and spectrum 2 a silica concentration of 35.2%. The difference in the silica concentration is 10.4%.

Determination of the Hardness

(23) The hardness of the granulated seed is carried out using a texture analysis instrument (Texture Analyser TA.XTplus from Stable Micro Systems, Germany). The principle of the measurement is, using a cylindrical measuring element 25 mm in diameter, to apply a pressure to a granule, the pressure with which the measuring element acts on the granule increasing until the shell of the granule bursts. The maximum force measured in kg is a measure for the hardness of the granule. 10 samples are measured per experiment so as to obtain a mean.

(24) The hardness determined for the individual examples of granulated seed compositions is shown in Table 2.

Determination of the Abrasion Resistance

(25) The abrasion resistance of the granulated seed is carried out with a friability tester (TAR 120 from Erweka, Germany). The drum of the testing instrument is charged with 20 g of granulated seed, and the seed is agitated in the drum at 40 rpm for 5 minutes. Thereafter, the seed is fractionated through an 800 μm screen, and the weight of the coarse-grained fraction is determined. The weight lost as a result of abrasion is the difference between the weight of the introduced seed and the weight of the coarse-grained fraction. The percentage abrasion based on the starting weight is a measure for the abrasion resistance.

(26) The abrasion determined for the individual examples of granulated seed compositions is shown in Table 2.

Determination of the Disintegration Time in Water

(27) The disintegration time in water, of the granulated seed, is determined in a ZT 31-type instrument (Erweka, Germany). For each experiment, two granules are immersed in a water bath which has a constant temperature of 14.8 to 15.2° C. The time which elapses until the coating of the granules has become fully detached from the seed kernel is a measure for the disintegration time. The measurement is terminated after a maximum of 60 minutes.

(28) The disintegration time in water determined for the individual examples of granulated seed compositions is shown in Table 2.

Determination of the Germination Ability

(29) To determine the germination ability of the granulated seed, 100 granules are placed into the pleats of a pleated paper (Hahnemühle, Dassel, accordion-pleated strips 110/20 mm, No. 3140). The pleated paper is transferred into a plastic dish (length×width×height: 170 mm×125 mm×60 mm) which is lined with a triple piece of folded filter paper strip (Hahnemühle, Dassel, wrapping strip 110/580 mm, No. 0585). The pleated paper is moistened uniformly with 35 m I of tap water. The dish is sealed tightly and stored at 20° C. After three days, the proportion of germinated seeds and of abnormal seedlings is determined. Abnormal seedlings are damaged seedlings, deformed seedlings or seedlings with uneven development, or seedling which show signs of rot. Abnormal seedlings were identified by shortened roots, deformed or discoloured leaves or seedlings whose root tips show signs of black discoloration. Each measurement is repeated four times.

(30) The germination ability of clean rapeseed (winter oilseed rape variety Dimension, thousand-seed weight 6.3 g) is determined by way of comparison.

(31) The germination ability determined for each of the examples of granulated seed composition is shown in Table 3. The results demonstrate that seed granulated with the aid of silica has a higher germination ability after three days than granulated seed without silica and has similarly a high germination ability as non-granulated, clean rapeseed.

(32) TABLE-US-00003 TABLE 2 Hardness, abrasion and disintegration time in water of individual granulated seed compositions. Hardness Abrasion Disintegration Example (kg) (%) time (min) 1 1.848 2.88 >60 2 1.491 2.83 >60 3 1.573 1.9 >60 4 1.47 2.05 >60 5 1.947 1.38 >60 6 1.967 1.63 >60

(33) TABLE-US-00004 TABLE 3 Germination ability of individual granulated seed compositions. Germination ability Abnormal Example after 3 days (%) seedlings (%) 1 86.5 3.25 2 84.25 3.5 3 82.25 5 4 80.25 3.25 5 80.5 4.75 6 77 5.25 Clean rapeseed 85.75 3