Plant husbandry – Coated or impregnated seed – method or apparatus
Reexamination Certificate
1999-09-20
2001-05-15
Poon, Peter M. (Department: 3643)
Plant husbandry
Coated or impregnated seed, method or apparatus
C071S064070, C504S100000
Reexamination Certificate
active
06230438
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
[Not Applicable].
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
[Not Applicable].
FIELD OF THE INVENTION
This invention relates to improved seed coatings for agriculture.
BACKGROUND OF THE INVENTION
This invention provides for seed coatings which comprise water insoluble polymers which absorb water, resist passage of water and are freeze labile. The seed coatings are useful for fall planting in cold climates.
SUMMARY OF THE INVENTION
This invention provides for a seed coated in a continuous, adherent water impervious coating to control germination until after exposure to freezing temperatures said coating comprising a water insoluble polymer having the following properties:
i. a glassification temperature of about 20° C. to about 0° C.;
ii. a water absorptivity value of at least 15% w/w after 24 hours; and
iii. a moisture vapor transmission rate of less than 200 gms per square meter per 24 hours; wherein the coating prevents the seed from imbibing water until the ambient temperature reaches the glassification temperature of the polymer and the absorbed water freezes and fractures the seed coating rendering it water permeable upon exposure to temperatures above 0° C. The polymer preferably has a glassification temperature of about 15° C. The preferred polymer has a water absorptivity value of at least 50% w/w, such as a water absorptivity value of at least 50% to 90% w/w. The polymer preferably has a moisture vapor transmission rate is about between 130 to 150 gms per square meter.
The preferred polymers are selected from the group consisting of styrene-acrylics, styrene butadienes, styrene-nitrile butadienes and vinyl acetate ethylenes.
The seeds suitable for use in this invention include the following plants: Brassica spp.
Medicago sativa,
Melilotus spp., Trifolium spp.,
Glycine max, Lens esculenta, Pisum sativum, Cicer arietinum,
Phaseolus spp., Triticum spp., Hordeum spp.,
Secale cereale,
X Triticosecale Wittmack),
Carum carvi, Phalaris canatiensis, Coriandrum sativum
L., Lolium spp.,
Zea mays,
and Avena spps.
The seed coatings may include Rhizobium inoculum, fungicide, fertilizer and insecticide.
This invention further provides for a method of inhibiting germination in a seed by enveloping the seed in a continuous, water impervious coating comprising a water insoluble polymer having the properties set forth above.
In addition to a method of inhibiting germination this invention provides for a method for fall planting of cold weather plants said method comprising the step of planting seed in a field two weeks prior to the expected date of the first hard freeze wherein the seed is coated with a continuous water impervious film comprising a water insoluble polymer having the properties set forth above.
DETAILED DESCRIPTION
Introduction
This invention involves the novel use of a polymer as a seed coating for seeds that are to be planted in fall for spring germination. Such seed are expected to survive freezing winter temperatures and to reliably germinate. The coating of this invention are sufficiently water impermeable that they fully prevent the seeds from germinating under normal conditions. The coatings are able to absorb water into their structure without passing sufficient water through to the seed to begin germination. Upon freezing, the water in the coat proteins expand or form crystals that induce mechanical shear on the coat and create micro fracturing. Upon return of the seed to temperatures above freezing, water passes through the fractures and germination begins.
The advantage of such films is that the seed can be planted in fall and germination will reliably begin in early spring when conditions might not readily permit equipment into the fields.
Definitions
“Cool season or weather plants” refers to plants that can germinate, grow, flower and mature at temperatures below 25° C. Examples include wheat and canola.
“Continuous” in the context of seed coating refers to a coating that has no breaks exposing the seed surface ambient moisture sufficient to initiate the germination process.
“Dye” is a colorant that is added to the mixture of chemicals that form the seed coating.
“Expected date of soil freeze up” is the predicted date upon which the soil surface remains frozen throughout the day.
“Fertilizer” refers to macro and micro nutrients needed for healthy plant growth.
“Fungicide” refers to chemical compositions that inhibit the growth of fungal plant pathogens.
“Germination” refers to the period of time following seed dormancy when physiological and physical changes undergone by a seed immediately prior to the first indications of growth.
“Glassification or glass transition temperature” refers to that temperature at which a polymer changes from a viscous or rubber condition to a hard and relatively brittle one.
“Moisture vapor transmission rate” refers to the rate at which water passes through a polymer film.
“Opacity agents” refers to agents that reduce the transparency of the seed coating.
“Pesticide” refers to a composition that affects the viability or a plant pathogen including insects, fungi, bacteria and nematodes.
“Polymer” a chemical composition with repeating units. The units may be identical units or units having a predictable percentage of similar components.
“Rhizobium inoculum” refers to a composition comprising bacteria from the genera of Rhizobium.
“Styrene-acrylics” refers to a polymer which comprises both stryene and acrylic monomers.
“Styrene butadienes” refers to a polymer which comprises both stryene and butadiene monomers.
“Styrene-nitrile butadienes” refers to a polymer which comprises styrene, acrylonitrile and butadiene.
“Vinyl acetate ethylenes” refers to a polymer which comprises both vinyl acetate and ethylene (bivinyl) monomers.
“Water insoluble” refers to a polymer that is not solvated in water or does not disperse on a molecular level in water. Functionally, a water insoluble polymer is one from which no more than 5% of any individual polymer component is extractable by hot water (150° F.).
“Water impervious” refers to a polymer film that is sufficiently impassable to water that seed dormancy is maintained where a seed is coated with the film as compared to an uncoated seed.
“Water permeable” in the context of a seed coating refers to a polymer film that is allows sufficient moisture to pass that seed dormancy in a seed coated with the water permeable film is ended and germination can begin.
Polymers of Use in the Invention
The physical characteristics of the polymers for use in this invention are provided above. The preferred polymers are latex. Latex is a general term for a stable emulsion of polymers in water. The term includes butadiene and styrene copolymers (elastomeric), stryene-butadiene copolymers (resinous), butadiene with styrene and acrylonitrile, chloroprene copolymers, methacrylate and acrylate ester copolymers, vinyl acetate copolymers, vinyl and vinylidene chloride copolymers, ethylene copolymers, fluorinated copolymers, acrylaminde copolymers, stryrene-acrolein copolymers, and pyrrole and pyrrole copolymers. These polymers can be modified to have active groups such as carboxy groups.
Additives include surfactants, initiators, stabilizers, cross linkers, antioxidants, UV stabilizers, reducing agents, colorants and plasticizers.
Latices are produced by emulsion polymerization. Emulsion polymerization is a process by which the monomers are present in an aqueous suspension as small beads of 0.05 to 5 nm. The monomers are permitted to interact with micelle bodies (surfactants) to form globules. The globules serve as a reservoir of monomers for the polymerization that takes place in the aqueous phase. In the presence of an initiator, the monomers polymerize into polymeric particles.
Because this invention depends on the physical properties of the polymers it is not possible to provide a single set of conditions which adequately serves to produce a suitable polymer. The properties of the plastics will depe
Enders Nicholas
Zaychuk Kevin S.
Grow Tec Inc.
Nguyen Son T.
Poon Peter M.
Townsend and Townsend / and Crew LLP
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