WO1997036471A1

WO1997036471A1 - Gelatin-based coatings for plant seeds and propagules

Info

Publication number: WO1997036471A1
Application number: PCT/US1997/004937
Authority: WO
Inventors: Peter A. C. Chown
Original assignee: Monsanto Company
Priority date: 1996-03-29
Filing date: 1997-03-27
Publication date: 1997-10-09
Also published as: AU2549197A; TW436262B; GB9606663D0; ZA972714B

Abstract

A liquid composition for coating plant seeds or other propagules includes gelatin, desiccant, water, and preferably active ingredients, such as, nutrients, pesticides and herbicides, trace elements, nematicides and safeners. The liquid composition is applied onto seeds or other propagules as a coating using a suitable device, preferably a rotating auger steeping system, an immersed conveyor steeping system or an electrostatic coater. The applied coating is then dried to form coated seeds or plant propagules. The coated seeds or other propagules are planted or stored for future use.

Description

1 GELATIN-BASED COATINGS FOR PLANT SEEDS AND PROPAGULES

FIELD OF THE INVENTION

The present invention relates to a liquid composition for coating plant seeds and propagules, a process for making film-forming liquid compositions, a process and apparatus for coating liquid compositions onto plant seeds and propagules and to coated seeds and propagules.

BACKGROUND OF THE INVENTION

An ever growing world population and its resultant need for food has motivated agronomists to seek new and improved methods to maximize crop yields and product quality for every hectare of land under cultivation. With this goal in mind, the agronomist of today has found it desirable and advantageous to enhance plant growth by use of nutrients and to protect their crop from planting through harvest from a multitude of adversities by use of a variety of agents.

Seeding, which is the beginning stage of the agronomist production cycle, involves placing a plant seed or a propagule directly in a field or placing a plant seed or a propagule in a nursery and then transferring to a field. Direct seeding in a field can expose the seed to a number of potential adverse factors. These factors include injury to the seed from the sowing process itself, washing away of the seed upon rainfall or watering, being eaten by animals, and partial premature germination. One of the countermeasures which developed in the art was the coating and/or encapsulating of the unprotected seed utilizing various agents and techniques. Some of these coating agents include clays or analogous materials of clay minerals, and any of several derivatives of alginic acid (e.g. calcium, sodium or potassium salts or propylene glycol alginate). Various machines for the application of the coating to the unprotected seed have likewise developed in the art.

The currently employed methods for commercial coating of potatoes is by spraying powder or liquid onto potatoes as potatoes are passed through on rollers. The coating applied in this manner adheres to only about 35 to 60% of the surface area of the potatoes. In Europe most of sugarbeet seed is pelleted before being planted. The pellet material is often blended with active ingredients such as Gaucho and Thiram. The pellets are expensive to produce and oversized seeds are wasted in the process. The pellets are generally brittle and many pellets break down during planting. A number of different approaches to coating and/or encapsulation seed coatings have been proposed. For example, Kono et al. article published in the Journal of the Japanese Societv of Agricultural Machinery, Vol. 57, No. 5, pp. 41-46 (1995) discloses coating seeds with alginic acid. Garrett et al. paper published in Applied Engineering in Agriculture, Vol. 10, No. 2, pp. 183-187, (1994) discloses using a loop wire dipped into a solution of sodium alginate for coating seeds. The seed passes through a meniscus of the sodium alginate gel causes the gel to coat it. The coated seed is then contacted with calcium chloride to form a calcium alginate skin. Similarly, Kono et al. in "Study of the Practical Application of Gel Coated Seed (Part 1) Principle of Coating Mechanism", published in the Journal of the Japanese Societv of Agricultural Machinery. Vol. 56, No. 5, pp. 13-18 (1994) discloses coating vegetable seeds with sodium alginate and using calcium chloride as a hardening agent. Prakash et al. reported in Indian J. Exp. Biol.. 31(2), 161-7, (1993) on encapsulation of seeds of Sesbania seban with polyacylamide and alginate gel. Prakash et al. noted that encapsulation of seed on a carrier-entrapped rhizobia with gelatin capsule reduced or totally inhibited symbiosis. Barow et al. discloses the use of capsules for feeding seeds to livestock for purpose of seed dispersal and resowing in remote areas.

Roeber et al, Lebensm-Wiss Technol.. 24(5), 466-8, (1991) discloses coating celery tubers with agarose, kappa-carajeenan, calcium alginate or pectin gel.

Several prior art articles disclosed incorporation of living organisms in an alginate gel coating. The living organisms are intended to biologically control a variety of agricultural pests.

U.S. Pat. No. 4,808,430 discloses a method of processing a plant seed wherein a coating treatment is applied to a plant seed with an aqueous alkali salt solution of an aqueous gel to form a coating layer and the coating layer is reacted with an aqueous solution of a divalent or trivalent metal salt to render the coating layer insoluble in water. The improvement is accomplished by encapsulating the plant seed with an air bubble. There is a long-standing still unsatisfied need for a film-forming composition (1) which is easy and inexpensive to manufacture and apply to seeds and propagules, (2) which does not unduly interfere with germination, (3) which can carry active ingredients and (4) which can cover substantially the entire surface of seeds or propagules. Similarly, there is a need for devices that efficiently, reliably and efficiently coat seeds or propagules with film-forming compositions, and especially film-forming compositions which carry active ingredients.

Thus, one object of the present invention is to provide an easy to apply, relatively inexpensive coatings for plant seeds and propagules. Another object of the present invention is to provide an apparatus for easily and efficiently coating plant seeds and propagules.

A further object of the present invention is to provide a liquid coating composition which when contacted with seeds or propagules forms a thin film on their surfaces, Yet another object of the present invention is to provide a coating for seeds or propagules which includes active ingredients so that upon planting such active ingredients are in the vicinity of the seed, the propagule or the resulting plant.

Still another object of the present invention is to provide a coating for seeds which is compatible with and carries insecticides, pesticides, nematicides, herbicides nutrients, trace elements and/or safeners.

A still further object of the present invention is to provide a coating for seeds and propagules, which substantially does not interfere with germination.

Still another object of the present invention is to provide a liquid coating which, when charged, adheres quickly and efficiently to seeds having opposite electrostatic charge imparted to their surfaces.

Another object of the present invention will become apparent to those skilled in the art upon studying this disclosure. SUMMARY OF THE INVENTION

A coating composition of the present invention comprises gelatin, water and a desiccant. The composition is preferably film-forming and preferably it also includes one or more active ingredients, such as, nutrients, trace elements, pesticides, nematicides, fungicides, herbicides, nematicides and safeners. The gelatin-based liquid composition of the present invention is coated onto plant seeds or plant propagules using any suitable coating device, preferably a rotating auger steering system, conveyor steeping system or an electrostatic system, constructed in accordance with the present invention. The coating is dried and the coated seeds are planted or stored for future use. Upon planting the gelatin coating substantially insulates the seed from moisture. When the amount of moisture is above a certain level, the moisture reaches the seed. This assures that germination does not occur at moisture levels that are insufficient to support complete germination. Additionally, when the gelatin coating includes active ingredients, the active ingredients are efficiently deposited into the soil near the seeds and/or plants when the coated seeds are planted. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of seeds coated with two layers of gelatin-based coating in accordance with the present invention. FIG. 2 is a cross section of a seed coated with a single layer of a gelatin-based coating in accordance with the present invention.

FIG. 3 is a perspective view of one embodiment of an apparatus constructed in accordance with the present invention.

FIG. 4 is a side-elevational view of another embodiment of an apparatus constructed in accordance with the present invention.

FIG. 5 is a side-elevational view of a third embodiment of the apparatus constructed in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION

Surprisingly, it has been discovered that plant seeds or plant propagules can be efficiently coated with a liquid gelatin-based coating composition formulated in accordance with the present invention. The coating compositions of the present invention have been found to be film-forming, i.e., upon contacting with seeds or propagules they form a thin liquid film that adheres to the surface. Moreover, the coating composition of the present invention can be efficiently and inexpensively applied at slightly above ambient conditions (i.e., 35°C or higher but below temperatures that damage the seed or other propagule). The liquid coating of the present invention includes gelatin, a desiccant and water. The coating preferably also includes active ingredients which enhance plant growth and/or protect the seed, other propagule or the resulting plant from pests, fungi and other perils. The liquid coating of the present invention can be applied by any suitable apparatus but it is preferably applied to seeds using an electrostatic coating system, a conveyor steeping system or an auger steeping system, constructed in accordance with the present invention. The seeds or other propagule coated in accordance of the present invention are easier to plant and they do not partially germinate in the presence of the amount of moisture which is insufficient to cause complete germination. Any animal or vegetable-based gelatin can be used in connection with the present invention, including the food-grade (sterilized) gelatin having a ph in the range of 3.5 to 8.0 and non-food grade gelatin. Presently preferred is an animal, food grade gelatin having a pH in the range from about 5 to about 6.5. The hardness of solidified gelatin can be described by its Bloom value. Generally, gelatin having Bloom values in the range from about 50 to about 300 can be used in connection with the present invention. The preferred Bloom values vary depending on the specific seeds that are coated and the specific composition of the formulation. Generally, the preferred Bloom values are in the range from about 150 to about 250. Specifically, for potatoes Bloom values in the range from about 180 to about 200 are preferred. It has been discovered that the coating composition made from gelatin having the Bloom values in this range flows onto and adheres to the potatoes and it remains flowable even at relatively low ambient indoor temperatures. Similarly, for sugar beets the preferred gelatin has Bloom values in the range from about 150 to about 250. For soy beans the preferred Bloom values are from about 180 to about 220. Finally, for cotton seeds the Bloom value of the gelatin is preferably about 180. The amount of gelatin in the coating composition is generally from about 2 to about 25 grams per liter of the coating solution but from about 80 grams to about 125 grams per liter on tubers and bulbs seeds. Preferably, the amount of the gelatin is in the range from about 2 grams to about 20 grams per liter of the coating solution but from about 80 to about 100 grams per liter on tubers and bulbs seeds. Any desiccant that can solidify gelatin to form a solid coating on the seed without cross linking the gelatin, can be used in connection with the present invention. The presently preferred desiccant is gypsum. The reason gypsum is preferred is that it absorbs water from the gelatin solution quickly to produce a gel. The amount of desiccant in the coating composition should be sufficiently large to produce a gel that adheres to the seeds that are being coated. However, the amount of the desiccant should be sufficiently low to keep the gel flowable during the time period required for the application of the coating. Generally, and especially when gypsum is used as a desiccant, the concentration of the desiccant is in the range between about 0.25 grams to 1.5 grams per gram of gelatin, preferred is 0.5 grams to 1 gram of desiccant per gram of gelatin.

In addition to gelatin, a desiccant and water, the coating composition of the present invention can preferably include a number of optional ingredients. Tallow can be added to increase the release rate of any active ingredient in the composition. Bulking agents, such as, clay, and preferably bentonite, can be added to give more body to the liquid coating composition. Coating compositions which include bulking agents produce more rounded coated seeds. Such coated seeds are generally easier to plant when using mechanical planters. The concentration of the bulking agent can be up to about 50 percent of the solids by volume.

An important aspect of the coating of the present invention is that it can be a carrier for active ingredients, such as, nutrients, trace elements, herbicides, pesticides nematicides, safeners, and fungicides. Specifically, the following insecticides are particularly useful as active ingredients in coating compositions of the present invention applied to the following seeds and propagules:

Seed Active Ingredient Brand Name Companv

Cereals Di sulfo ton Dysyston Bayer

Cereals Disulfoton Frumin Sandoz

Cereals Disulfoton Frumin United Phosphorus

Cereals Imadocloprid Gaucho Bayer

Cereals Lindane Lindalo Rhone-Poulenc

Cereals Methiocarb Draza Bayer

Cotton Disulfoton Dysyston Bayer

Cotton Fipronil Regent Rhone-Poulenc Seed Active Ingredient Brand Name Company

Cotton Imadocloprid Gaucho Bayer

Cotton Lindane Lindalo Rhone-Poulenc

Cotton Phoxim Volaton Bayer

Cotton Thiodicarb Larvin Rhone-Poulenc

Maize Bendiocarb Garvox AgrEvo

Maize Benfuracarb Oncol Otsuka

Maize Diazinon Basudin Ciba

Maize Diazinon Basudin Nippon Kayaku

Maize Diazinon Basudin Drexel

Maize Diazinon Basudin M. Agan

Maize Fipronil Regent Rhone-Poulenc

Maize Furathiocarb Deltanet Ciba

Maize Imadocloprid Gaucho Bayer

Maize Isazofos Miral Ciba

Maize Lindane Lindalo Rhone-Poulenc

Maize Phoxim Volaton Bayer

Maize Thiodicarb Larvin Rhone-Poulenc

Potatoes Diazinon Basudin Ciba

Potatoes Diazinon Basudin Nippon Kayaku

Potatoes Diazinon Basudin Drexel

Potatoes Diazinon Basudin M. Agan

Potatoes Disulfoton Dysyston Bayer

Potatoes Fipronil Regent Rhone-Poulenc

Potatoes Imadocloprid Gaucho Bayer

Potatoes Isazofos Miral Ciba

Potatoes Lindane Lindalo Rhone-Poulenc

Potatoes Methiocarb Draza Bayer

Rice Benfuracarb Oncol Otsuka

Rice Diazinon Basudin Ciba

Rice Diazinon Basudin Nippon Kayaku 8

Seed Active Ingredient Brand Name Company

Rice Diazinon Basudin Drexel

Rice Diazinon Basudin M. Agan

Rice Disulfoton Dysyton Bayer

Rice Fipronil Regent Rhone-Poulenc

Rice Furathiocarb DeltaNet Ciba

Rice Imadocloprid Gaucho Bayer

Rice Isazofos Miral Ciba

Rice Lindane Lindalo Rhone-Poulenc

Soybeans Furathiocarb DeltaNet Ciba

Soybeans Thiodicarb Larvin Rhone-Poulenc

Vegetables Benfuracarb Oncol Otsuka

Vegetables Diazinon Basudin Ciba

Vegetables Disulfoton Dysyston Bayer

Vegetables Disulfoton Frumin Sandoz

Vegetables Disulfoton Frumin United Phosphorus

Vegetables Furathiocarb DeltaNet Ciba

Vegetables Imadocloprid Gaucho Bayer

Vegetables Isazofos Miral Ciba

Vegetables Phoxim Volaton Bayer

Vegetables Thiodicarb Larvin Rhone-Poulenc

The following fungicides are particularly useful as active ingredients in coating compositions of the present invention applied to the following seeds:

Seed Active Ingredient Brand Name Companv

Cereals Bitertanol Bay cor Bayer

Cereals Carboxin Vitavax U,AE,Sundat,Jin HungFine

Cereals Diniconazole Spotless Sumitomo

Cereals Ethirimol Milgo Zeneca

Cereals Fenitropan Volparex Egyt Pharmaceutica

Cereals Fenpiclonil Beret Ciba

Cereals Fludioxonil Beret Gold Ciba Seed Active Ingredient Brand Name Company

Cereals Flutriafol Impact Zeneca

Cereals Fuberidazole Voronit Bayer

Cereals Guazatine Panoctine Rhone-Poulenc

Cereals Hexaconazole Anvil Zeneca

Cereals Imazalil Fungaflor Jansen

Cereals Iminoctadine Befram Dainippon

Cereals Iprodione Rovral Rhone-Poulenc

Cereals Methfuroxam Trivax Uniroyal (no US reg.)

Cereals Nuarimol Trimidal Dow Elanco

Cereals Oxine Copper Quinolate Ciba

Cereals Oxycarboxin Plantvax Uniroyal

Cereals Quintozene Terraclor U, AgrEvo, Mitsui

Cereals Tebuconazole Folicur Bayer

Cereals Tetraconazole Eminent Isagro

Cereals Thiabendazole Mertect Merck & Co.

Cereals Triadimenol Bayfidan Bayer

Cereals Triticonazole Real Rhone-Poulenc

Cotton Bitertanol Baycor Bayer

Cotton Etridiazole Terrazole Uniroyal

Cotton Fenpiclonil Beret Ciba

Cotton Metalaxyl Ridomil Ciba

Cotton Pencycuron Monceren Bayer

Cotton Quintozene Terraclor Uniroyal, Agrevo, Mitsui

Cotton Methyl Tolclofos Rizolex Sumitomo

Maize Fenitropan Volparex Egyt Pharmaceutica

Maize Thiram Tripomil Elf Atochem

Maize Thiram Thianosan Elf Atochem

Potato Benalaxyl Gal ben Isagro

Potato Captan Captan Z, MA. Rallis, C, Drexel

Potato Fenpiclonil Beret Ciba 10

Seed Active In redient Brand Name Company

Potato Fludioxonil Saphire Ciba

Potato Iprodine Rovral Rhone-Poulenc

Potato Imazalil Fungaflor Jansen

Potato Metalaxyl Ridomil Ciba

Potato Oxadixyl Sandofan Sandoz

Potato Pencycuron Monceren Bayer

Potato Quintozene Terraclor U, AgrEvo, Mitsui-Toatsu

Potato Thiabendazole Merfect Meek

Potato Tolciofos-methyl Rizolex Surmitomo

Potato Validamycin Validacin Takeda

Rice Carboxin Vitavax U,AE,Sundat, Jin Hung F

Rice Fenitropin Volparex Egyt Pharmaceutica

Rice Fludioxonil Celest Ciba

Rice Guazatine Panoctine Rhone-Poulenc

Rice Hymexazol Tachigaren Sankyo

Rice Iminoctadine Befran Dainippon

Rice Oxolinic acid Stamer Sumitomo

Rice Pefurazoate Healthied Hokko, Ube

Rice Pencycuron Monceren Bayer

Rice Pyrόquilon Coratop Ciba

Rice Tecloftalam Shirihagen S Sankyo

Rice Validamycin Validacin Takeda

Soybean Bitertanol Baycor Bayer

Soybean Carboxin Vitavax Uniroyal

Soybean Metalaxyl Ridomil Ciba

Soybean Thiabendazole Mertect Merck

Vegetables Benalaxyl Galben Isagro

Vegetables Bitertanol Baycor Bayer

Vegetables Captan Captan Z, MA, Rallis

Vegetables Ethirimol Milgo Zeneca Seed Active In redient Brand Name Company

Vegetables Etridiazole Terrazole Uniroyal

Vegetables Fludioxonil Saphire Ciba

Vegetables Hexaconazole Anvil Zeneca

Vegetables Hymexazole Tachigaren Sankyo

Vegetables Imazalil Fungaflor Jansen

Vegetables Iprodione Rovral Rhone-Poulenc

Vegetables Metalaxyl Ridomil Ciba

Vegetables Nuarimol Trimidal DowElanco

Vegetables Oxydixyl Sandofan Sandoz

Vegetables Oxine-copper Quinolate Ciba

Vegetables Oxolinic acid Starner Sumitomo

Vegetables Oxycarboxin Plantvax Uniroyal

Vegetables Pencycuron Monceren Bayer

Vegetables Propamocarb Pre vi cur AgrEvo

Vegetables Quintozene Terraclor U, AgrEvo, Mitsui-Toatsu

Vegetables Tebuconazole Folicur Bayer

Vegetables Tetraconazole Eminent Isagro

Vegetables Thiabendazole Mertect Merck

Vegetables Thiram Tripomil Elf-Atochem

Vegetables Thiram Thianosan UCB

Vegetables Tolclofos-methyl Rizolex Sumitomo

Vegetables Tradimenol Bayfidan Bayer

Vegetables Trifumizole Trifmine Nippon Soda

Vegetables Triflumizole Terraguard Uniroyal

Vegetables Validamycin Validacin Takeda

An example of safeners for use as active ingredients in the coatings of the present invention are disclosed in U.S. Pat. No. 5,225.570 and Hungarian HU 24537 O. An example of nematicides are those disclosed in U.S. Pat. No. 5.389.680.

Additional active ingredients include: Gaucho and Tachigaren manufactured by Bayer and Thiram manufactured by Ciba. Where it is important that an active ingredient does not come in contact with the seed, multiple coatings can be applied to the seeds. The inner coating in contact with the outer surface of the seed then acts as a barrier between the incompatible seed and the incompatible active ingredient which is included in an outer coating. Multiple coatings can also be employed to include a certain type of active ingredients in one coating and a different active ingredient in another coating. This approach is particularly advantageous where the active ingredients in different coating layers are incompatible with each other or one another.

To produce a liquid composition of the present invention, gelatin is added to water and the mixture is agitated until the gelatin is dissolved. Preferably, the agitation is provided by pumping the gelatin-water mixture. Gelatin is preferably dissolved at atmospheric pressure. The temperature is generally in the range from about room temperature to slightly below the boiling point of water. Preferably, the temperature is in the range from about 75 °C to about 99°C. A desiccant, preferably gypsum, and active ingredients can be added to the liquid solution before, after or concurrently with the addition of gelatin. However, preferably gypsum and/or any active ingredients are added after gelatin is dissolved in water to form a solution.

The liquid composition of the present invention can be applied onto the seeds or plant propagules using any suitable apparatus. However, the liquid composition is preferably applied using one of the systems constructed in accordance with the present invention: an electrostatic system, a rotating auger steeping system or a conveyor steeping system. At the present, the electrostatic system is especially preferred. Briefly, the electrostatic system of the present invention imparts a negative charge to the seed and a positive charge to the liquid coating composition. As the positively-charged liquid comes in contact with the negatively-charged surface of the seed, the liquid is attracted to and quickly coats the entire seed.

In the rotating steeping system of the present invention, seeds are fed into one or more tanks containing the liquid coating composition of the present invention. The seeds or propagules are transported from the tanks into a drying zone drum using an auger. Finally, in the conveyor steeping system of the present invention, seeds are placed on a conveyor belt. The seeds are dipped at least once and preferably at least twice in the liquid coating composition of the present invention. The conveyor belt then carries the seeds into a drying zone where forced air dries and solidifies the coating applied to the seeds.

Drying of the liquid composition of the present invention is generally carried out at a temperature in the range from ambient room temperature to about 70°F, preferably in the range from about 35°F to about 40°F. The dried coated seeds or propagules can be sowed using standard sowing machinery or by hand. In the alternative, the coated seeds can be stored for later application. If the temperature and humidity are relatively high or if prolonged storage is contemplated, it is desirable to place on the surface of the coating an inert material, preferably a powder material, such as, chalk or talcum powder. Such inert material reduces the tendency for the seed to stick together or agglomerate.

An important advantage of the present invention is that the coating generally covers more than about 90 percent of the surface area of the seeds or propagules, most often over 98 percent. Another advantage of the present invention is that moisture required to break down the coating is also sufficient to effect complete germination of the seed or propagule. A further advantage of the present invention is that the germination of the coated seed or propagule is quicker than that of pelletized seeds. It has additionally been found that the liquid composition of the present invention can be applied as a coating over previously pelletized seeds such as pelletized sugar beets. Such applications can be made by apparatus such as described in Fig. 3-6. Among the benefits of such coatings over pelletized seeds is improved germination especially when active ingredients are included in the gelatin coating and not added to the pellet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS COATED SEEDS

The present invention will now be described in connection with the preferred embodiments depicted in the drawings. Referring now to the drawings, FIG. 1 depicts a potato 10 which is coated with two layers 12 and 14 of gelatin-based coating composition of the present invention. The inner coating layer 12 includes gelatin, gypsum and active ingredients, a fungicide and a pesticide. The outer coating layer 14 includes gelatin, a fertilizer and trace elements.

FIG. 2 depicts a sugarbeet seed 20 coated with a single layer of gelatin-based coating 22 of the present invention. The three preferred systems of applying the liquid coating composition of the present invention to seeds are depicted in FIGS. 3-6. Currently, the most preferred system is the electrostatic system depicted in FIG. 3. This device described in FIG. 3 can also be used in accordance with the present invention to coat seeds without the operation of the electrostatic unit. THE ELECTROSTATIC SYSTEM

Referring now to FIG. 3, an electrostatic system constructed in accordance with the present invention is generally designated by a numeral 30. The system 30 includes an outer stationary container 32 and a coaxial inner container 33. A rotating disc 34, coaxial with the container 33, is positively-charged by an electrostatic unit (not shown). The currently preferred electrostatic unit is operated 5,000 to 10,000 volts, preferably, 8,000 volts and is manufactured by Binks Ltd., Brown Hills, Walsall, England. This standard electrostatic unit is preferably modified to generate pulsating voltage of 5,000 and 10,000 volts using R4-1D Airless timer manufactured by Omcron. The spinning disc 36 extends downward into the inner container 33. The disc 36 is centrally mounted on a shaft 37 which is operatively connected to and powered by a motor 39. The motor 39 is mounted by supports 40 partially shown in FIG. 3. A seed hopper 43 communicates with the inside container 33 via a spout 41.

The liquid composition of the present invention is stored in a heated tank 45. A conduit 47 carries the liquid from the tank 45 onto the spinning disc 36. The flow of the liquid through the conduit 47 is controlled by a value 49. The conduit 47 is negatively charged by the electrostatic unit.

The conta ner 33 is rotated by a shaft 51 which, in turn, is rotated by a pulley 53 driven by an endless V-belt 55 extending between the pulley 53 and a pulley 57. The pulley 57 is powered by a motor 60. In operation, voltage of the electrostatic unit (not shown) is turned so as to negatively charge the liquid conduit 47 and positively charge the container 33. The motors 39 and 60 are then activated. The motor 39 causes the spinning disc 36 to rotate and the motor 60 causes the rotation of the container 33. Seeds 42 from the seed hopper

43 and liquid from the heated tank 45 are then introduced into the inner drum via the spout 41 and the conduit 47, respectively. The seed comes in contact with positively- charged inner container 33 and as the result becomes negatively-charged. The negatively-charged seed is instantly coated with the liquid composition which becomes positively-charged upon exit from the negatively-charged conduit 47.

The coated seeds are then removed from the system 30 and allowed to dry, preferably using forced air (not shown). A next batch of seed is then introduced into the inner container 33 via the spout 41 and contacted with the liquid composition from the tank 45 as previously described.

THE CONVEYER STEEPING SYSTEM

A steeping system constructed in accordance with the present invention, shown in FIG. 4, is designated generally by a numeral 400. Seeds 402 to be coated in accordance with the present invention is stored in an input hopper 410. A tank 412 holds a liquid coating composition 420. A control valve (not shown) controls the rate at which seeds 402 from the input hopper 410 are introduced into the liquid coating composition 420. The temperature of the composition 420 is controlled by an electrical heater 425. The seeds 402 after being submersed in the liquid coating composition 420 is deposited onto an endless conveyor belt 430 by a rotating paddle 435. The belt 430 is partially enclosed by a cold air duct cover 437. Air forced into the volume defined by the air duct cover 437 dries the liquid coating on the seeds as they travel on the conveyor belt 430. The coating composition is stirred by a recirculating pump 445 which withdraws the composition via an inlet pipe 450 and returns it via the outlet pipe 455. The level sensor 460 controls the level of the liquid in the tank 412.

The seed carried by the belt 430 is deposited on a second conveyor 460 which carries it into and through a pressure chamber 470. Air is forced around the conveyor belt 460 and into the exhaust duct 475 and the air duct 480 which communicates with the duct defined by the enclosure 437. The coated seeds 402 are carried by the conveyor 460 out of the pressure chamber 470 and dropped onto a third conveyor 490 which carries them into storage (not shown). THE ROTATING AUGER STEEPING SYSTEM

Referring now to FIG. 5, a numeral 500 generally designates the continuous auger steeping system constructed in accordance with the present invention. Seeds 502 s are fed on to an endless belt 505 of a conveyor 507. The belt carries the seeds 502 into a first coating tank 509 which contains a liquid coating composition 510 of the present invention. The seeds 502 are dropped from the belt 505 into the tank 509. After being immersed in the coating composition 510, the seeds 502 are brought out of the tank 509 by an auger 51 1 which is rotatably mounted such that a section thereof extends into the o tank 509. The auger 51 1 carries the seed into a drying section 515. A fan 512 forces air though the drying section 515 to dry the coating on the seed while the coated seeds 502 are being carried through the drying section 515 by the auger 51 1. The forced air is removed from the section 515 via an exhaust duct 520.

From the drying section 515, the auger carries seeds 502 into a second coating s tank 525 which contains a liquid coating composition 526. The composition 526 is generally slightly different and includes different active ingredients from that of composition 509. The coated seeds 502 are carried from the second tank 525 by the auger 51 1 into a second drying section 530 where they are dried in a rotary mesh drum 535 using forced air circulated by a fan 531. The dried coated seed is then deposited 0 onto an endless belt 550 of the output conveyor 555 which carries and deposits it into storage containers (not shown). EXAMPLES

The following examples are provided for illustrative purposes only. They are not intended to restrict the scope of the claims in any manner. 5 Example 1

1.5 grams of 150-160 Bloom gelatin, distributed by Croda Colloids Ltd., Foundry Lane, Ditton Widnes, Cheshire, WA 88UB, U.K., was added to 75 mL of water. The resulting mixture was stirred until the gelatin was completely dissolved. 0.75 grams of gypsum and a small amount of red food dye was then added to the gelatin solution to 0 visually indicate whether the seed is coated. The mixture was stirred and transferred to the electrostatic coating unit of the type shown in FIG. 3. The electrostatic unit was operated as previously described with pulsating voltage of 5,000 and 10,000 volts. 200 grams of Zulu (late) sugarbeet seeds were placed in the electrostatic coating unit and batch fed from the seed feed hopper into the inner container 33 (coating bowl). The coating seeds were spun in the coating bowl until they dried. The dried coated sugarbeet seeds were inspected to determine uniformity of the coating. It was observed the dyed coating covered substantially all of the surface of the seeds.

Example 2

Two grams of food-grade gelatin granules (160-180 bloom) manufactured by Croda Colloids Ltd., Foundry Lane, Ditton Widnes, Cheshire WA 88 UB, U.K. was placed in a container and 200 mL of boiling water was added. Sixty-five grams of Gaucho supplied by Bayer Chemicals was then added to the water solution of gelatin. Four grams of gypsum was added to Gaucho-containing gelatin solution. The resulting mixture was blended thoroughly with a hand blender until all component parts were dissolved. One gram of food coloring dye was then added to the solution and the dye- colored solution was allowed to cool to a temperature of about 60-80°F.

The cooled dye colored solution was then poured into a tank 45 of an electrostatic unit of the type shown in Fig. 3. The motor 39 was activated to begin spinning of the disc 36. About 100,000 sugarbeet (Zulu) seeds supplied by Hillesdog Chemical Company were placed in a hopper 43. The electrostatic unit was then activated. The solution from the tank 45 was allowed to flow onto the spinning disc 36 and sprayed onto the spinning seed introduced into the container 33 from the hopper 43.

Inspection of the seed showed that coating was present on substantially all surface area. Example 3

One kg of food-grade 160-180 Bloom gelatin manufactured by Croda was dissolved in 10 liters of warm water to form a solution. Six mL of Monceren was added to the solution. 500 grams of gypsum was then added to the solution and the mixture was agitated. Potatoes were then individually dipped into the gypsum-containing solution and the dipped potatoes were allowed to dry at ambient room temperatures. The potatoes were found to have a uniform coating which covered substantially all of their outer surface.

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Many changes and modifications will occur to those skilled in the art upon studying this disclosure. All such changes and modification that are within the spirit of the present invention are intended to be included with the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1. A liquid composition for coating plant seeds or plant propagules, said composition comprising: a. from about 2 grams to about 125 grams of gelatin per liter of the liquid composition; b. from about 0.25 grams to about 1.5 grams of a desiccant per gram of gelatin composition; and, c. water.

2. The composition according to claim 1 wherein the gelatin has a pH in the range from about 3.5 to about 8.0.

3. The composition according to claim 1 wherein the gelatin is food grade and has a pH in the range from about 5 to about 6.5.

4. The composition according to claim 3 wherein the concentration of gelatin is in the range from about 2 grams to about 25 grams per liter on the liquid composition.

5. The composition according to claim 4 wherein the concentration of gelatin is in the range from about 80 to about 125 grams per liter of the liquid composition.

6. The composition according to claim 1 wherein the desiccant is gypsum.

7. The composition according to claim 1 wherein the concentration of the desiccant is in the range from about 0.5 grams to about 1 gram per gram of gelatin.

8. The composition according to claim 1 further comprising at least one active ingredient which is selected from the group consisting of nutrients, trace elements, safeners, nematicides, pesticides, herbicides, fungicides, and mixtures thereof.

9. The composition of claim 6 further comprising at least one active ingredient.

10. The composition of claim 9 further comprising tallow.

11. The composition of claim 6 further comprising a bulking agent.

12. The composition of claim 9 further comprising a bulking agent.

13. A process for making a liquid coating composition for coating plant seeds which comprises the following steps: a. dissolving gelatin in water to form a solution, the concentration of gelatin being in the range from about 2 grams per liter of the solution to about 125 grams per liter of the solution; b. adding one or more desiccants, the concentration of the desiccant being in the range from about .25 grams to about 1.5 grams of desiccant per gram of gelatin; and c. stirring the mixture comprising gelatin, water and desiccant to form the liquid coating composition.

14. The process of claim 13 wherein the desiccant is gypsum,

15. The process of claim 14 further comprising a step of adding at least one active ingredient.

16. The process of claim 13 wherein step (b) precedes step (a).

17. The process of claim 16 further comprising adding tallow to the liquid composition.

18. The process of claim 16 further comprising adding a bulking agent.

19. A coated seed comprising: a plant seed or a propagule, a coating covering substantially the entire outer surface of said seed, said coating including gelatin and a desiccant, said gelatin being substantially free of cross- linking bonds.

20. The coated seed or other propagule of claim 19 wherein said coating further includes an active ingredient.

21. The coated seed or other propagule of claim 19 wherein the desiccant is gypsum.

22. An electrostatic system for coating seeds or plant propagules with a coating composition, said system comprising: a. means for imparting an electrostatic charge to seeds; b. means for imparting an electrostatic charge to the coating composition opposite to that of the seeds; c. means for contacting said charged seeds with the oppositely charged coating composition to coat the seeds.

23. A steeping system for coating seeds or other propagules with a liquid coating composition, said system comprising: a. a tank for holding said liquid coating composition; b. a conveyor for moving seeds, said conveyor being submersed in said coating composition; c. a hopper for holding seeds or propagules and feeding them into the coating composition directly above the submersed end of the conveyor; d. a container for holding said coating composition; e. a dryer for drying seeds or propagules as they are carried out from the liquid coating composition.

24. A rotating auger system for coating seeds or propagules with a liquid coating composition, said system comprising: a. a container for holding said liquid coating composition; b. a dryer for drying coated seed or propagules; and c. an auger for carrying seeds or propagules into said container and from said container into the dryer.