CA2161294A1 - Seed coating for enhancing the level of selenium crops - Google Patents
Seed coating for enhancing the level of selenium cropsInfo
- Publication number
- CA2161294A1 CA2161294A1 CA002161294A CA2161294A CA2161294A1 CA 2161294 A1 CA2161294 A1 CA 2161294A1 CA 002161294 A CA002161294 A CA 002161294A CA 2161294 A CA2161294 A CA 2161294A CA 2161294 A1 CA2161294 A1 CA 2161294A1
- Authority
- CA
- Canada
- Prior art keywords
- selenium
- seed
- plant
- seed coating
- copolymers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01C—PLANTING; SOWING; FERTILISING
- A01C1/00—Apparatus, or methods of use thereof, for testing or treating seed, roots, or the like, prior to sowing or planting
- A01C1/06—Coating or dressing seed
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D9/00—Other inorganic fertilisers
- C05D9/02—Other inorganic fertilisers containing trace elements
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Environmental Sciences (AREA)
- Dentistry (AREA)
- Toxicology (AREA)
- Engineering & Computer Science (AREA)
- Plant Pathology (AREA)
- Wood Science & Technology (AREA)
- Zoology (AREA)
- Pest Control & Pesticides (AREA)
- Soil Sciences (AREA)
- Agronomy & Crop Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Organic Chemistry (AREA)
- Pretreatment Of Seeds And Plants (AREA)
Abstract
A seed coating for enhancing the level of selenium in crops and therefore ensuring that sufficient levels of selenium are present in the resulting animal feed or foodstuff is described. The invention provides both a seed coating and method of coating a seed which provides a sufficient amount of selenium to the seed for uptake by the plants to produce selenium sufficient crops. The seed coating and method ensures that the selenium remains adhered to the seed in uniform, consistent amounts and which further imparts abrasion-resistance to the seed in order to reduce the toxicity risk of handling selenium-coated seeds.
Description
~16129 1 -SEED COATING FOR ENHANCING THE LEVEL
OF SELENIUM IN CROPS
FIELD OF THE INVENTION
The present invention relates to a seed coating for enh~ncin~ the level of selenium in crops. The invention provides a seed coating, a method of coating a seed, which provides a snffiçient amount of selenium to the seed for uptake, and a coated seed.
BACKGROUND OF THE INVENTION
I ~rge areas of North America, western Europe and Australia/New 7e~1~n-1 produce crops that are deffcient in selenium, copper and other essential trace elements. The absence or deficiency of these trace elem~ont~
affects the overall food chain, res111ting in plants and nltim~tely ~nim~lc deficient in these minerals. Significant deficiencies in any or a combin~,tion of specific trace elements will affect the overall health of many ~nim~1~ and may lead to a variety of acute health problems. Accoldingly, a correct balance of trace elements is required for optimal health and livestock production. In particular, selenium is a trace element required by ~nim~ls for a variety of biological processes. It is essential that ~nim~ls receive a~fo~iate levels of se1eninm In all classes of livestock (dai~y, beef, swine and poultry) selenium deficiency causes a variety of chronic and acute health problems.
Numerous animal n~1tritionists have worked on the problem of se1eni11m deficiency in ~nim~1~ for years. While crops are not in themselves affected by low levels of selenium in the soil, the use of crops co~ i.-g almost no selenium as animal fodder or feedstuffs leads to selenium deficiencies in all classes of ~nim~ls, in(~ 1ing hllm~ns Numerous methods have evolved to address the problem of selenium deficiency, which have certain problems and 1imit~tion~ associated with them.
. 216129~
Selenium is routinely provided to livestock in mineral blocks (referred to as free choice), injections and/or as mineral supplements mixed with feed.
With free choice supplements, the amount of selenium each animal S int~kes is not controllable and varies widely because some ~nim~lc over self-3~1minicter and others under self-~lminicter. Therefore, some of the herd/flock receive inadequate amounts and others excessive amounts of seleni~lm (Hemingway, R.G. 1982).
Injections of selenium are time col-su~ -g, costly, need to be repeated, and involve additional h~n~lling of ~nim~lc which is dangerous to the handler and stressful to the ~nim~l Using off-farm premixed feeds cont~ining selenium is often not al~pro~liate since many farmers use mostly home-grown feed and do not purchase feed from suppliers. These farmers would have to mix selenillm into their farm-grown feed, which is problematic since many farms lack suitable mixing facilities and h~ntlling selenium is potentially dangerous. In cases where pre-mixed concentrated feeds are purchased, the amount of selenium required and the amount of concçntrated feed used varies with each farm.
Thus, custom selenium supplement~tion for each farm may be required, adding to the complexity. These variables coupled with the fact that additional h~n(lling of the feed at the feed plant would be required to mix in the selenium would make the pre-mixed concentrate feeds more expensive.
Therefore, pre-mixed feeds are not an ideal solution to the selenillm deficiency problem.
There are a significant number of hectares of corn aIld other fodder crops grown in selenium deficient areas. Corn is the most important feed grain in the United States for all classes of livestock because of its high quality and high yields. Silage corn is grown as whole crop feeds on many dairy and beef farms. Corn and cereal silage are produced in C~n~d~ Farm grown corn, pulse crops and cereal grains are also important feeds for the swine and poultry industry.
s Several corn growing areas are generally deficient in selenium in~ lin~, for example, ~ritime provinces, Quebec, Ontario, parts of British Columbia, New Fngl~n~l, Illinois, Inrli~n~ Michigan, New York, North Carolina, Ohio, Pennsylvania and Wisconsin. These areas are also important dairy producers. In cooler areas, cereals replace corn in selenium deficient areas.
While it has been shown experiment~lly that selenium can be effectively applied by spraying a seleni~lm solution onto plants (Gupta et al 1988), this practice is not in commercial use in view of the numerous limit~ti~ns associated with plant spraying. In particular, spraying plant foliage with a selenium solution is inconvellient because it requires an additional passover the field with a carefully prepared solution and expensive calibrated spraying equipment. Timing of the spraying is very important; spraying cannot be done in windy weather and rain will wash off the spray. Also plants must be at a sufficiently advanced growth stage to ensure uptake but applying at a stage of over advanced growth will result in mechanical damage to the crop from the tractor and application equipment.
The only commercial method now in use anywhere in the world for enh~n~ing selenium in crops grown on selenium deficient soils is by application of a slow-release prilled selenium fertilizer on gr~s.~l~n~lc usually by aircraft. Selenillm applied to the soil in this way is taken up less efficiently than selenium delivered via the seed coating method. This method is used primarily in Australia and New 7e~1~ntl and has rarely been used in North America to date on a commercial scale.
....
Application of selenium as a fertilizer is impractical for the following reasons:
i) the selenium fertilizer would have to be in a prilled form since powdered selenium does not have the physical characteristics requ*ed for proper h~ncllin~ and blending, ii) prilled selenium fertilizer cannot be applied with conventional farm equipment because the application rates are far too low.
That is, convention~l farm equipment cannot be slowed down or re~ll~te~l enough to accurately apply the selenium with the high degree of accuracy that is required. The lowest rate of fertilizer this equipment can accurately apply is 20 kg/ha whereas prilled selenium fertilizer must be applied at a rate of 1 kg/ha, iii) blending selenium with other fertilizers requ*es the use of prilled selenium fertilizer;
iv) it is pr~ctic~lly impossible for a farmer to blend prilled selenium with other fertilizer on their farm since this requires the proper mixing equipment (which farmers do not have) to ensure that exact minute amounts of selenium are urli~o~ly blended throughout large volumes of fertilizers;
v) the only forms of prilled selenillm fertilizer that are ~;urlenlly commercially available are slow-release which is unsuitable for certain plants such as corn since the selenium is not rapidly available in the soil;
vi) the blending process is potentially dangerous to the farmer because of the physical h~n~lling and the potential of inh~ling a*-borne selenium dust or the potential of skin contact or absorption of the selenium dust;
vii) applying seleniumblended with fertilizer is impracticalbecause all fields require different amounts and types of fertilizer which would require custom blending for every field which would be difficult and expensive;
216129~
viii) blending the prilled selenium with an inert ~ t~nt (eg vermiculite) would add to the cost to fertilize the field.
There has been a need to deliver selenium to crops via a seed coating technology that overcomes the aforementioned limit~tions and other problems associated with delivering the selenium with fertilizers.
Seeding rates for individual crops are relatively UlU~Ol"l over wide geographic areas, usually varying by less than 20~ in contrast to fertilizer rates which vary greatly (0 - 500 kg/ha of product). Delivering selenillm to the crop via the seed, rather than fertilizer, is better since a controlled level of selenium in the seed coat provides a more predictable and optimal amount of selenium in any given crop. Further, it is easier for the farmer to assess whether the correct amount of selenium has been applied as rate of application is related to emerging plant population which can be checked visibly. Such checks cannot be done with fertilizer application rates. Further, fertilizer is not suitable to deliver selenium because fertilizer needs vary so significantly from field to field and crop to crop.
Custom blending selenium whether at a fertilizer plant or on a farm can easily lead to errors in selenium application rates. Low rates will lead to the health problems livestock experience with selenium deficiency and excessive rates may threaten animal health, plant health or the euvilonlllent.
A coated seed simplifies these quality control issues since the exact amount of selenium applied to each seed at the seed-coating plant can be very accurately controlled.
As the exact amount of selenium can be put on each seed and the plant uptakes the selenium at a predictable and consistent rate, it is far easier to control the exact amount of selenium in the crop. Other methods do not allow for this level of control. Seed coating allows for the control, consistency ' 216129~
and repeatability from year to year that is required for proper livestock management practices.
Accordingly, there has been a need for a technology that overcomes the aforementioned problems and limit~tions. Specifically, there has been a need for a technology that effectively raises selenium levels in crops in an efficient, uniro~, collvenient, consistent, safe m~nner that also allows for accurate, consistent manipulation of the level of selenium in the crop. Seed coating technology can achieve this goal.
In s-lmm~ry, there has been a need for selenium seed coating technologies that assures the farmer that his crop will conlaill enough selenillm every year, regardless of geographical location, without additional work or inputs and that specifically address the following criter 1. Toxicity Selenium is potentially toxic to both plants and ~nim~ls above certain levels and, accordingly, must be handled as such.
a) Phytotoxicity With respect to plants, the primary issue is phytotoxicity. Selenium applied directly to plants above certain levels, may result in reduced plant growth or possibly kill the plant. In the past, it has also been considered thatthe application of selenium directly to the seed of the plant would have a phytotoxic effect in view of the relatively high concentration of selenium immediately adjacent the new plant roots during germin~tion. This was considered to be of particular concern especially as the levels of selenillm areincreased. Previous studies have shown that selenium can negatively affect seed germination and elongation of young roots in several crop species (Levine 1925, Spencer and Siegel 1978, Carlson et al. 1989). In the study by Carlson et al (1989) the length of the young roots of solghulll, which is related to corn, were reduced by concentrations of selenillm of 16-32 mg/litre 216129~
.
of solution. In another study, selenium re~lllce-l yield of sor~lull, by up to 95% (Carlson et al. 1991). In this trial, sodium selenate was more deleterious to sor~ulll than sodium selenite. Wheat and barley may be more resistant to selenium than sorghulll (Carlson et al. 1989, Ylaranta 1983).
b) Human Toxicity With respect to hllm~n~, the primary issue is the toxicity associated with the inh~l~tiQn of air-borne selenium or absorption of the selenium through the skin. Past experimental seed coating techniques using selenillm, such as that disclosed in Gupta et al (1983) simply involved a process where the seed shell is made sticky with gum arabic and peat moss to which a slurry of water and selenium is added. The seed was dried leaving a certain amount of selenium attached to the seed. ~n-lling of the seed leads to two problems. The first is the loss of the selenium coat from the seed by abrasion thereby leaving an inconsistent amount of selenium on each seed reslllting in inconsistent and unpredictable levels of selenium in each plant and therefore leading to unpredictable levels of selenium in the feed. The second problem is the danger of inh~ling air-borne selenium produced through h~nflling the seed or prilled fertilizer or the absorption of the selenium through the skin when workers handle the seed or prilled fertilizer.
OF SELENIUM IN CROPS
FIELD OF THE INVENTION
The present invention relates to a seed coating for enh~ncin~ the level of selenium in crops. The invention provides a seed coating, a method of coating a seed, which provides a snffiçient amount of selenium to the seed for uptake, and a coated seed.
BACKGROUND OF THE INVENTION
I ~rge areas of North America, western Europe and Australia/New 7e~1~n-1 produce crops that are deffcient in selenium, copper and other essential trace elements. The absence or deficiency of these trace elem~ont~
affects the overall food chain, res111ting in plants and nltim~tely ~nim~lc deficient in these minerals. Significant deficiencies in any or a combin~,tion of specific trace elements will affect the overall health of many ~nim~1~ and may lead to a variety of acute health problems. Accoldingly, a correct balance of trace elements is required for optimal health and livestock production. In particular, selenium is a trace element required by ~nim~ls for a variety of biological processes. It is essential that ~nim~ls receive a~fo~iate levels of se1eninm In all classes of livestock (dai~y, beef, swine and poultry) selenium deficiency causes a variety of chronic and acute health problems.
Numerous animal n~1tritionists have worked on the problem of se1eni11m deficiency in ~nim~1~ for years. While crops are not in themselves affected by low levels of selenium in the soil, the use of crops co~ i.-g almost no selenium as animal fodder or feedstuffs leads to selenium deficiencies in all classes of ~nim~ls, in(~ 1ing hllm~ns Numerous methods have evolved to address the problem of selenium deficiency, which have certain problems and 1imit~tion~ associated with them.
. 216129~
Selenium is routinely provided to livestock in mineral blocks (referred to as free choice), injections and/or as mineral supplements mixed with feed.
With free choice supplements, the amount of selenium each animal S int~kes is not controllable and varies widely because some ~nim~lc over self-3~1minicter and others under self-~lminicter. Therefore, some of the herd/flock receive inadequate amounts and others excessive amounts of seleni~lm (Hemingway, R.G. 1982).
Injections of selenium are time col-su~ -g, costly, need to be repeated, and involve additional h~n~lling of ~nim~lc which is dangerous to the handler and stressful to the ~nim~l Using off-farm premixed feeds cont~ining selenium is often not al~pro~liate since many farmers use mostly home-grown feed and do not purchase feed from suppliers. These farmers would have to mix selenillm into their farm-grown feed, which is problematic since many farms lack suitable mixing facilities and h~ntlling selenium is potentially dangerous. In cases where pre-mixed concentrated feeds are purchased, the amount of selenium required and the amount of concçntrated feed used varies with each farm.
Thus, custom selenium supplement~tion for each farm may be required, adding to the complexity. These variables coupled with the fact that additional h~n(lling of the feed at the feed plant would be required to mix in the selenium would make the pre-mixed concentrate feeds more expensive.
Therefore, pre-mixed feeds are not an ideal solution to the selenillm deficiency problem.
There are a significant number of hectares of corn aIld other fodder crops grown in selenium deficient areas. Corn is the most important feed grain in the United States for all classes of livestock because of its high quality and high yields. Silage corn is grown as whole crop feeds on many dairy and beef farms. Corn and cereal silage are produced in C~n~d~ Farm grown corn, pulse crops and cereal grains are also important feeds for the swine and poultry industry.
s Several corn growing areas are generally deficient in selenium in~ lin~, for example, ~ritime provinces, Quebec, Ontario, parts of British Columbia, New Fngl~n~l, Illinois, Inrli~n~ Michigan, New York, North Carolina, Ohio, Pennsylvania and Wisconsin. These areas are also important dairy producers. In cooler areas, cereals replace corn in selenium deficient areas.
While it has been shown experiment~lly that selenium can be effectively applied by spraying a seleni~lm solution onto plants (Gupta et al 1988), this practice is not in commercial use in view of the numerous limit~ti~ns associated with plant spraying. In particular, spraying plant foliage with a selenium solution is inconvellient because it requires an additional passover the field with a carefully prepared solution and expensive calibrated spraying equipment. Timing of the spraying is very important; spraying cannot be done in windy weather and rain will wash off the spray. Also plants must be at a sufficiently advanced growth stage to ensure uptake but applying at a stage of over advanced growth will result in mechanical damage to the crop from the tractor and application equipment.
The only commercial method now in use anywhere in the world for enh~n~ing selenium in crops grown on selenium deficient soils is by application of a slow-release prilled selenium fertilizer on gr~s.~l~n~lc usually by aircraft. Selenillm applied to the soil in this way is taken up less efficiently than selenium delivered via the seed coating method. This method is used primarily in Australia and New 7e~1~ntl and has rarely been used in North America to date on a commercial scale.
....
Application of selenium as a fertilizer is impractical for the following reasons:
i) the selenium fertilizer would have to be in a prilled form since powdered selenium does not have the physical characteristics requ*ed for proper h~ncllin~ and blending, ii) prilled selenium fertilizer cannot be applied with conventional farm equipment because the application rates are far too low.
That is, convention~l farm equipment cannot be slowed down or re~ll~te~l enough to accurately apply the selenium with the high degree of accuracy that is required. The lowest rate of fertilizer this equipment can accurately apply is 20 kg/ha whereas prilled selenium fertilizer must be applied at a rate of 1 kg/ha, iii) blending selenium with other fertilizers requ*es the use of prilled selenium fertilizer;
iv) it is pr~ctic~lly impossible for a farmer to blend prilled selenium with other fertilizer on their farm since this requires the proper mixing equipment (which farmers do not have) to ensure that exact minute amounts of selenium are urli~o~ly blended throughout large volumes of fertilizers;
v) the only forms of prilled selenillm fertilizer that are ~;urlenlly commercially available are slow-release which is unsuitable for certain plants such as corn since the selenium is not rapidly available in the soil;
vi) the blending process is potentially dangerous to the farmer because of the physical h~n~lling and the potential of inh~ling a*-borne selenium dust or the potential of skin contact or absorption of the selenium dust;
vii) applying seleniumblended with fertilizer is impracticalbecause all fields require different amounts and types of fertilizer which would require custom blending for every field which would be difficult and expensive;
216129~
viii) blending the prilled selenium with an inert ~ t~nt (eg vermiculite) would add to the cost to fertilize the field.
There has been a need to deliver selenium to crops via a seed coating technology that overcomes the aforementioned limit~tions and other problems associated with delivering the selenium with fertilizers.
Seeding rates for individual crops are relatively UlU~Ol"l over wide geographic areas, usually varying by less than 20~ in contrast to fertilizer rates which vary greatly (0 - 500 kg/ha of product). Delivering selenillm to the crop via the seed, rather than fertilizer, is better since a controlled level of selenium in the seed coat provides a more predictable and optimal amount of selenium in any given crop. Further, it is easier for the farmer to assess whether the correct amount of selenium has been applied as rate of application is related to emerging plant population which can be checked visibly. Such checks cannot be done with fertilizer application rates. Further, fertilizer is not suitable to deliver selenium because fertilizer needs vary so significantly from field to field and crop to crop.
Custom blending selenium whether at a fertilizer plant or on a farm can easily lead to errors in selenium application rates. Low rates will lead to the health problems livestock experience with selenium deficiency and excessive rates may threaten animal health, plant health or the euvilonlllent.
A coated seed simplifies these quality control issues since the exact amount of selenium applied to each seed at the seed-coating plant can be very accurately controlled.
As the exact amount of selenium can be put on each seed and the plant uptakes the selenium at a predictable and consistent rate, it is far easier to control the exact amount of selenium in the crop. Other methods do not allow for this level of control. Seed coating allows for the control, consistency ' 216129~
and repeatability from year to year that is required for proper livestock management practices.
Accordingly, there has been a need for a technology that overcomes the aforementioned problems and limit~tions. Specifically, there has been a need for a technology that effectively raises selenium levels in crops in an efficient, uniro~, collvenient, consistent, safe m~nner that also allows for accurate, consistent manipulation of the level of selenium in the crop. Seed coating technology can achieve this goal.
In s-lmm~ry, there has been a need for selenium seed coating technologies that assures the farmer that his crop will conlaill enough selenillm every year, regardless of geographical location, without additional work or inputs and that specifically address the following criter 1. Toxicity Selenium is potentially toxic to both plants and ~nim~ls above certain levels and, accordingly, must be handled as such.
a) Phytotoxicity With respect to plants, the primary issue is phytotoxicity. Selenium applied directly to plants above certain levels, may result in reduced plant growth or possibly kill the plant. In the past, it has also been considered thatthe application of selenium directly to the seed of the plant would have a phytotoxic effect in view of the relatively high concentration of selenium immediately adjacent the new plant roots during germin~tion. This was considered to be of particular concern especially as the levels of selenillm areincreased. Previous studies have shown that selenium can negatively affect seed germination and elongation of young roots in several crop species (Levine 1925, Spencer and Siegel 1978, Carlson et al. 1989). In the study by Carlson et al (1989) the length of the young roots of solghulll, which is related to corn, were reduced by concentrations of selenillm of 16-32 mg/litre 216129~
.
of solution. In another study, selenium re~lllce-l yield of sor~lull, by up to 95% (Carlson et al. 1991). In this trial, sodium selenate was more deleterious to sor~ulll than sodium selenite. Wheat and barley may be more resistant to selenium than sorghulll (Carlson et al. 1989, Ylaranta 1983).
b) Human Toxicity With respect to hllm~n~, the primary issue is the toxicity associated with the inh~l~tiQn of air-borne selenium or absorption of the selenium through the skin. Past experimental seed coating techniques using selenillm, such as that disclosed in Gupta et al (1983) simply involved a process where the seed shell is made sticky with gum arabic and peat moss to which a slurry of water and selenium is added. The seed was dried leaving a certain amount of selenium attached to the seed. ~n-lling of the seed leads to two problems. The first is the loss of the selenium coat from the seed by abrasion thereby leaving an inconsistent amount of selenium on each seed reslllting in inconsistent and unpredictable levels of selenium in each plant and therefore leading to unpredictable levels of selenium in the feed. The second problem is the danger of inh~ling air-borne selenium produced through h~nflling the seed or prilled fertilizer or the absorption of the selenium through the skin when workers handle the seed or prilled fertilizer.
2. Linear Rate Response and Repeatability from Year to Year Uptake of selenium by plant roots is regulated in part at least by energy requiring processes (Arvy 1993). Accordingly, the efficiency of selenium uptake depends on the energy status of the plant and growing conditions would be expected to affect selenium content. Selenium uptake is also affected by sulphur content of the soil. Some plant species are adapted to actively exclude selenium (Wu and Huang 1992). Based on these factors, the rate of uptake should vary within the year and from year to year.
Indeed, Gupta and Macleod (1994) reported that soybean cv. Maple Isle receiving 10 g/ha of selenium (as selenate) conlailled 599 ppb in 1989 and 1458 ppb in 1990 even though the two sites had similar soil characteristics.
-Unpredictable levels of selenillm uptake by the plant may lead to either deficient or toxic levels of selenium in the animal feed. Therefore, any commercially acceptable solution to the selenium deficiency problem has to overcome this as good livestock management practices requires that a farmer can accurately and consistently control the amount of selenium in the feed from year to year.
Indeed, Gupta and Macleod (1994) reported that soybean cv. Maple Isle receiving 10 g/ha of selenium (as selenate) conlailled 599 ppb in 1989 and 1458 ppb in 1990 even though the two sites had similar soil characteristics.
-Unpredictable levels of selenillm uptake by the plant may lead to either deficient or toxic levels of selenium in the animal feed. Therefore, any commercially acceptable solution to the selenium deficiency problem has to overcome this as good livestock management practices requires that a farmer can accurately and consistently control the amount of selenium in the feed from year to year.
3. Efficient Uptake Recovery rates for selenium applied (as selenate) to barley in the soil was at a rate of 4-10% (Ylaranta 1983). Similar rates of uptake efficiency occur with wheat ~tili7ing a variety of application methods (Stephen et al 1989). It has been demonstrated that corn takes up about 5~o of soil supplied selenium. Commercial available prilled selenium ~leci~ned for slow release, has been shown to be taken up with even less efficiency. Accordillgly, a tecllnolngy is required to hll~rove the uptake efficiency of selenium to reduce loss and risk of cont~min~ti-n to the ellvh~n~ ent
4. Distribution of Selenium in the Plant Corn is fed to rllmin~nt ~nim~lc either as a whole plant or as grain whereas non-rllmin~ntc, such as pigs and fowl, use only the grain portion of the corn or other crops. Thus for monograstrics it is important that the selenium is translocated to the cobs and not just stored in the leaves.
Previous work has shown a greater conce~ alion of selenillm in the grain compared to straw in barley and soybeans (Ylaranta 1983, Gupta and Macleod 1994, Carey and Allaway 1973). Uptake of selenium from a seed coat was expected to be more rapid than soil applied selenium because of the proximity of the new roots to the selenium. Since selenate is rapidly absorbed and translocated in the plant, it was expected that most of the selenate would be quickly stored in the young leaves.
216129~
Previous work has shown a greater conce~ alion of selenillm in the grain compared to straw in barley and soybeans (Ylaranta 1983, Gupta and Macleod 1994, Carey and Allaway 1973). Uptake of selenium from a seed coat was expected to be more rapid than soil applied selenium because of the proximity of the new roots to the selenium. Since selenate is rapidly absorbed and translocated in the plant, it was expected that most of the selenate would be quickly stored in the young leaves.
216129~
5. Optimum Selenium Formulation It is known that particular forms of selenillm do not work on particular plants. For example, selenium, as barium selenate, is not effective with corn in its uptake whereas for grass, uptake is effective. Accordhlgly, an optimal selenium form~ tion is required to ensure efflcient uptake.
6. Uniform Application on Seed Uneven application of selenium to seed results in some plants receiving greater selenium rates than others. Accordingly, because selenium is potentially phytotoxic, ~miform application of selenium to each seed is necess~ry to avoid some seeds receiving toxic levels of selenium.
In view of the problems of producing selenium enhanced plants without the associated risk of plant, human or animal toxicity, there has been a need for a convenient, effective method for addressing the problems associated with livestock production in selenillm deficient areas. Specifically,there has been a need for a convenient, effective method of ensllring plant uptake of selenium to produce plants which provide the required levels of selen-ium in animal feed in a consistent, reliable m~nner to enh~nce livestock vitality while ensuring that the plants, ~nim~l~ and handlers are not subjected to toxic levels of selenium.
Furthermore, there has also been a need for a method of supplying selenium to ~nim~lc through the animal feed in order to elimin~te the need for secondary tre~tment of the ~nim~l~ (injection~) while ensuring a constant and consistent supply of selenium in the ~nim~l~' diet.
Furthermore and more specifically, there has been a need for a seed coating technique in which a seed is coated with a seed coating cn~ i.,g selenium that accurately places an exact and ullirollll amount of selenium on each seed and thereafter covered by a water-soluble polymer film that encapsulates the entire seed. There has also been a need for a seed coating 21 6129~
.
technique where the polymer coating is sufficiently resilient to ~r~venl dustingoff so dust borne levels of selenium do not rise to toxic levels during normal h~n(lling of the seed and to prevelll each seed from ending up with non-l.,,irn..,, amount of selenium before pl~nting There has also been a S need for a seed coating technique where a mltrient, fungicide and/or biocide coat may be optionally provided between the seed treatment coat and the polymer film to enhance the early growth of the seed. There has also been a need for coated seeds which hllprove the flow of seeds during h~n-lling.
Seeds of certain crops, such as corn, are routinely treated with fungicides. Accordingly, there has also been a need for a selenium seed-coating technology that incorporates fungicides into the seed coats wherein the seed coats also provide a protective layer thus ren~lçring the fungicide/selenium treated seed safer to handle.
Past seed coating techniques have generally addressed the problems associated with hll~lovillg the growth of plants and have not addressed the problem of enh~n~ ing ~nimal fodder. Examples of soil and seed coating or treatment techniques are found in the prior art. For example, US patent 4,735,015 discloses a seed protective coating using a film forming composition comprisingpolyoxyethylene-polyoxybutylene block co-polymers for controlling water uptake by the seed.
US patent 3,911,183 discloses a seed coating process in which a seed is coated with polymer-pesticide film. Halogenated vinyl resin is used as a film former and pesticide carrier.
US patent 3,698,133 discloses a plant seed with a multiple coating.
The coating is in two layers, an inner porous coating permeable to water and an outer coating of a polymer with a controlled permeability to water. This patent discloses the use of additives to enhance particular functions of the plant.
216129~
US Patent 4,735,017 discloses a coated seed having inorganic additives in the coating.
US Patent 5,017,374 discloses a seed dressing which affords trace elements, such as Zn and Cr to livestock by plant uptake from the coated seeds using fungal spores.
US Patent 5,044,116 discloses a method for polymer coating of seed, which coating may inclllde additives.
US Patent 4,229,613 discloses compositions for the controlled release of trace nutrients into soil including selenium.
C~n~ n Patent Application 2,042,661 discloses a selenium composition for application to soil and pastures. The composition incllltles barium selenate in a slow release form and water-soluble selenium compound.
US Patent 4,388,303 discloses the use of selenium (as selenite absorbed soil) in a plant for repelling foragers by in-1ucing n~llse~
US Patent 4,656,083 discloses the conversion of selçnillm metal to odiferous dimethyl selenide by soil bearing selenium-metabolizing org~ni~m~
for repelling foragers.
US Patent 4,847,087 and 5,169,647 disclose adding selenium from selenium-in-sulfur compositions to soil for plant uptake so that rumin~nt ~nim~ls may receive nutrient selenium.
US Patent 4,880,628 discloses a sustained release composition for livestock having a trace element, for example selenium, in a slowly soluble cement.
' 2161294 SUMMARY OF THE INVENTION
The present invention relates to a seed coating for enh~ncin~ the level of selenium in crops. The invention provides a seed coating, a method of coating a seed, which provides a sufflcient amount of selenium to the seed for uptake, and a coated seed.
In accordance with the invention, a seed coating for enh~ncin~
selenium uptake into a plant is provided comprising:
an abrasion-resistant seed coating m~teri~l; and a sufficient amount of a selenium-cont~inine compound, sufficient to yield a nutritionally required amount of selenium in said plant.
The present invention is further directed to a coated seed for enh~n~n~ selenium uptake into a plant comprising:
a seed and a seed coating composition COlll~)liSillg an abrasion-resistant seed coating material and a sufficient amount of a selenium-co~ e compound, sufficient to yield a n~ltritionally required amount of selenium in said plant.
In one embodiment of the present invention there is provided a coated seed for enhancing selenium uptake into a plant comprising:
a seed and a seed coating composition comprising an abrasion-resistant seed coating polyvinyl acetate homopolymer em~ ion material and a sufficient amount of a selenium-co~ e compound, sufficient to yield 100 to 300 ng of selenium per gram dry weight of said plant.
The present invention is also directed to a method of coating seeds for enhancing selenium uptake into plants comprising the steps of:
a) solubilizing a selenium-collt~illille compound in water to form an aqueous selenium solution;
216I29~
b) mixing the aqueous selenium solution with a liquid polymer em~ ion to form a polymer/selenium solution;
c) mixing the polymer/selenium solution with a sufficient quantity of seeds to form a film coat on the seeds;
d) curing the seeds from step c) to form an abrasion-resistant protective coating on the seeds.
BRIEF DESCRIPIION OF THE DRAWINGS
These and other features of the invention will be more apparent from the following description in which reference is made to the appended drawings wherein:
Figure 1 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenillm content in whole corn grown from the coated seed for a 1991 test plot;
Figure 2 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenium content in whole corn grown from the coated seed for a 1992 test plot;
Figure 3 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenium content in whole corn grown from the coated seed for a 1993 test plot.
DETAILED DESCRIPIION OF THE INVENTION
In accordance with the invention, a seed-coating te~nology is provided which meets the requirements of a selenium-coated seed as set forth above, namely:
1) being non-phytotoxic to the growth of the plant and re(l~ ing the toxic risk to handlers of the seeds;
216129~
2) having a linear and reliable rate response with respect to uptake over the full range of selenium application rates and repeatability from year to year;
3) providing a uniform coating on each seed to ensure consistency between plants, resulting in an effective distribution of selenium within a number of plants;
4) providing an op~ lulll formnl~tion that ensures an efficient uptake of the selenium without wasting or losing selenium to the environment.
In accordance with the present invention, a seed coating incorporating a sufffcient amount of a selenium-cont~ining compound was developed. Said seed coating, when applied to a seed, f~ilitates an enhanced selenium uptake into the plants which develops from said seed.
The amount of the selenium-c~nt~ining compound which is added to the seed coating material is an amount sufffcient to yield a nutritionally required amount of selenium in the resulting plant. The nutritionally required amount of selenium in said resulting plant can range from any amount which is an increase in the plant to, but not in~ tling, an amount which would be deleterious or toxic to the animal upon eating said plant. In general, the target level for selenium in the feed depends on the overall feeding program and safe levels legislated in various countries. Thus, the nutritionally required amount of selenium to which the present invention is directed, can range from 100-400 parts per billion (ppb) (100-400 ng per gram dry weight of said plant). In a further embodiment of the present invention, the nutritionally required amount of selenium in said plant ranges ~om 100-300 ppb.
The sufficient amount of the selenium-collt~illil~g compound which is added to the seed coating material in order to yield the mltrition~lly required amount of selenium in said plants is based on a number of variables. These variables inchllle for example the selenium-co~ ne compound; the seed size; and the number of seeds sown per hectare.
The selenium-co~ il,g compound can be almost any selenium compound, for example salts or oxides of selenillm Typical selenium compounds can include sodium selçn~te, sodium selenite, selenium disulphide, selenium flioxi(le, selenium sulfur oxide, barium selenate, pot~ m selenate, pot~C~i-lm selenite, calcium selenate, r~lcillm selenite, and the like.
In one embodiment of the present invention, the selenium-col-l~ini"g compound is selected from sodium selen~tç, sodium selenite and selenium disulphide.
The absorption ability, or uptake of selenium by the plant will vary from one selenium-cont~inine compound to another. Thus, it will be obvious to persons skilled in the art that if a compound is selected which has a lower absorption ability, then a higher concentration of that selenium-c-ll-t~il,il-e compound would be required in the coating composition to yield the n~ltritionally required amount of selenium in the plant, as defined above.
As by way of an example, in one embodiment of the present invention, sodium selenate is used as the selenium-collt~ lle compound. In this example, the sodium selenate is added to the seed coating composition, so that the final amount of selenium in the soil is between 5 and 50 grams of selenium per hectare.
The amount of selenium-con~ illg compound added to the seed coating material will also vary, as noted above, depending upon the size of the seed and the seed sowing rate. For example, if a high number of seed per hectare is planted, then the amount of selenium-col-L~i,-i.,g compound in the coating composition would be less than for a crop which has a lower 216129~
.
seeding rate. The sowing rate for any particular crop would remain constant.
For example the sowing rate for corn is a~roxi...~tely 75,000 seeds per hectare. Thus, if, when sodium selenate is used as the selenium-co.~ g compound, the amount of selenium in the coating composition for corn would range from 5 to 50 grams per 75,000 seeds or between 5 and 50 grams of selenium per hectare.
In one embodiment of the present invention, where corn is the seed which is coated, and sodium selenate is the selenium-cont~ining compound, to obtain 300 ppb concentration of selenium in the corn plant, 15 to 25 grams of selenium should be added to the seed coat m~teri~l per 75,000 seeds, and more specifically 16 to 21 grams.
The present invention is directed to a selenium-c~ g seed coating composition, which, when said seed coating composition is applied to a seed, will yield a plant with a higher level of selenium. The present invention is directed to a seed coating composition for any type of seed, wherein said resulting plant or part thereof, is used for livestock feed or for human consumption. There is no limitation on the type of seeds which can be used according to the present invention. For example, the present invention is directed to a seed coat composition which can be used to coat seeds for the production of pulse crops, cereal crops, large grain crops, grass crops and other broad leaf crops and the l~e, destined for animal or human consumption.
Accord~-g to the present invention, either the grain of the plant, or the whole plant, can be used as a feed source. There may be some variation between the amount of selenium which is present in the grain as compared to the whole plant. Thus, if it is known that only the grain or the seed of the crop is used as a food source, the amount of selenium-collt~inil~g material used in the coating composition may require adjustment. In all cases, however, the factors discussed above will be selected to ensure that the 216129~
resulting plant, or plant part, which is used as a feedstuff contains a nutritionally required amount of selenium.
According to the present invention, any polymer m~tçri~l can be used in the seed coating composition, as the seed coat m~teri~l There are a number of polymer coating compositions which have been described in the prior art. Any of these materials and methods would be useable in the present invention. Suitable polymer type m~t~ lc have been described in prior art references, of which U.S. Patents 4,251,952, 3,905,152, 5,106,648 and 5,300,127 are examples.
According to the present invention, suitable water soluble coating material can be selected from homopolymers of butylated polyvinylpyrrolidone, poly(vinylpyrrolidone/1 -hexadecene), villyllJyllolidone/styrene copolymers, vil~ yllolidone/vinyl acetate copolymers, alkylatedpolyvillyl~yrrolidone, polyvinyl acetate, polyvinyl acetatehomopolymer emulsions, fully or partially hydrolized polyvinyl alcohol, polyvinyl alcohol homopolymer emulsions, copolymers of vinyl pyrrolidone and vinyl acetate, poly(methyl vinyl ether)maleic anhydride copolymers, vinyl acetate/butyl acrylate compounds, acrylic copolymers, styrene/acrylic ester copolymers vinyl acetate/ethylene copolymers, vinyl acetate/VeoVa 10/butyl acrylate terpolymers and the like. The method of preparing said polymers for use as seed coat material are well known in the art.
In one embodiment of the present invention, an addition~l abrasion-resistant coating is provided as a second outer coating. If only one coat is used, then there will be a certain amount of selenium on the outside of the coating composition and, thus, the seed will still be hazardous to handle. A
second coating will form an abrasion-resistant protective coating on the seeds which will completely encase the selenium irmer coat and, thus, will render the seed safer for h~n(lling purposes. Any of the polymer m~teri~lc which have been described for the irmer coat could be used for the outer coat material.
The seed coating can also contain other materials which are required S or will enhance the germin~tion or growth of the seed. These further materials can include nutrients such as pot~ m, phosphate or nitrogen, biological nutrients, or a biocide inrlnlling fungicides.
In the ex~mple where a two-layered seed coating is used, a drying agent may be added to the seeds once the first seed coat has been applied to ensure water removal from the inner selenillm coat to enhance the storage of the seeds. Any suitable drying agent known in the art can be used for this purpose. For example, a suitable drying agent such as calcium carbonate, calcium oxide, calcium hydroxide, vermiculite, ~ tom~ceous earth, gypsum, talcum, bentonite, kaolin, and various metal silicates can be used.
Any seed coating method can be used accoldhlg to the present invention. In general, abrasion-resistant selenium-coated seeds are prepared by first dissolving the selenium-co.~ g material in water to form a water-selenium solution co~ g a known amount of selenium. The solution is then mixed with a liquid polymer emulsion to form a polymer/selenium solution. A quantity of seeds are then mixed with the polymer/selenium solution to form a film coat on the seeds. The seeds are then cured to form an abrasion-resistant coating on the outer surface of said seeds.
As described above, in one embodiment of the present invention, an additional abrasion-resistant coating is provided on the seeds to protect the handler from the selenium coating m~teri~l In this embodiment, the seeds, after being coated with the polymer/selenium solution, are partially cured and may be mixed with a drying agent, as described above, to form a drying agent coat on the seeds. The drying agent coat may be used to ensure water removal from the inner selenium coat to enhance the storage of the seeds.
~ 2l6l2sa The seeds are then mixed with a second liquid polymer emulsion to form an abrasive-resistant protective co~ting on the seeds. The seeds are then cured.
While this invention is described in detail with particular reference to preferred embodiments thereof, said embodiments are offered to illustrate but not to limit the invention.
EXAMPLES
Example 1- Selenium Seed Coating on Corn Seeds The selenium seed coating was field tested over a three year period in order to investigate the above criteri~ narnely the phytotoxicity of seleniumon the growing plant, the selenium uptake characteristics by the growing plant and the repeatability over several growing seasons in view of the seed coating te~lmiques.
Seed of corn hybrid G4066 (Funk Hybrids) was coated with selenium using a polymer seed coat of a polyvinyl acetate homopolymer emulsion as the seed coat material.
The selenium was added to the seed coat material at a rate of 0, 5, 10, 20 or 40 g of selenium per 75,000 seeds (equivalent to grams of selenium per hectare), in the form of sodium selenate.
The selenium-coated seeds were planted in mid-May to early June on a Monroe series soil (Eutric Eluviated Brunisol), a sandy loam soil known to be low in selenium. Prior to seeding, the field was cultivated and fertilized with 300 kg/ha of nitrogen and 70 kg/ha each of pot~c~inm and phosphorus.
Lime was applied when necessary.
Weeds were controlled pre-emerge with the herbicide Atrazine (1.8 kg/ha). Weeds were also controlled by hand-weeding and post-emerge broadleaf herbicides.
The corn was planted by hand, using corn jabbers, in rows spaced 75 cm apart. Seeding was done in order of increasing selenium concen~l~Lion to ."i~i."i,e cross-cont~min~tion Plants within a row were spaced 18 cm apart to give a final plant population of 75,000 plants/ha.
Each plot consisted of three 1.8 meter long rows. The selenium application rates were randomized within each of four replicates to give a randomized complete block design.
Plants were harvested each year in October. Plots were harvested in order of increasing seleniumrates to "~ i"~i~e cross-cont~min~tion. The entire centre row was harvested (whole plants), weighed, then chopped with a commercial chopping m5~ ine. A represelllaliv~ sample of chopped m~teri~l was taken, weighed and dried to a colLslalll weight. Drying temperature was low (40~C) to minimi7e vol~tili7~tion of selenium. After drying, samples were reweighed, and ground to pass through a 1 mm mesh.
Samples were ground in order of increasing selenium concentration to ", i .~ i ", i,e cross-cont~min~tion.
Selenium analysis was performed by inductively coupled plasma mass spectroscopy (ICPMS) after sample decomposition by rnicrowave digestion.
Five ml of nitric acid and a selenium stable isotope internal standard were added to 0.5 g samples which were digested in sealed Teflon vessels using microwave power. Volatile selenium hydride was generated and the quantity of selenium determined by isotope dilution ICPMS. Accuracy of the determin~tion was verified by use of a certified reference material. The data was analyzed statistically with SAS software using a randomi7e~1 complete block model.
Levels of selenium in the control corn plants were aylJloxi~ tely 2.7-9.1 ppb dry matter in the first sample. These rates are typical for crops grown in coastal British Columbia and other low selenium areas around the world. Applied selenium increased selenium content in the corn in a linear fashion in all trials (see Figures 1-3 and Table 1). Figures 1-3 and Table 1 show that for every 10 g/ha increase in application rate of selenium, as sodium selenate, selerlium c-~ncçntration in corn increased by 120-180 parts per billion. The target level for seleninm in feed depends on the overall feeding program and safe levels leFi~l~ted in various countries. To obtain 300 ppb concentration, which is commorlly considered desirable, 16-21 g selenium/ha should be added to the seed coat. This corresponds to the rates of 10-20 g/ha of selenium commonly applied as fertilizer in New 7e~1~n(1 Based on an average yield of 16.6 tonne/ha, the efficiency of recovery of applied selenium was in the range of 20-33%. Repeatability over the three year trial period is evident from Figures 1 to 3.
' - 216129~
Table 1 Effect of selenium seed coating on yield and selenium uptake in whole crop and grain or corn in 1993 Whole Corn Grain Intended Actual Yield Se Se ~o Se Se rate rate t/hacontent uptake uptake g/ha g/ha ppb g/ha ppb 0 0.0044 18.4 2.7 0.05 -- 6.5 0 + CACO3 0.05 15.8 1.5 0.02 -- not tested 4.4 17.459.1 1.0 22.8 not tested 10.8 17.4167.5 2.8 26.0 not tested 10+CaCO3 12.0 19.5129.5 2.6 21.6 not tested 18.8 16.5288.2 4.7 25.1 193.0 30.7 16.1439.0 6.1 19.9 not tested 35.6 11.4516.9 7.1 19.9 not tested Yield did not appear to be appreciably affected by selenium application except perhaps at 40 g/ha (Table 1). No visual symptoms associated with selenium applications were apparent.
s The percentage of the applied selenium that was taken up by the crop ranged 20-26~o and, accordingly, the percentage of uptake was not affected by selenium application rate.
Selenium concentration in the grain (193 ppb) was lower than in the whole plant (288 ppb) so for selenium enhancement of grain, 50~o more selenium is required in the seed coat.
216129~
The variability of selenium content in individual plants ranged from 25% - 40% of the mean (Table 2). This in~lic~tes that less than 3~o of the plants contained more than 1.8 times of the desired selenium content and further, (lçmonstrates the ulliro~ y of the coating. This seed coating technique provides very few seeds with potentially phytotoxic levels of selenium.
Table 2 Variabilib in the selenium content of individual corn plants at 20 and 40 g Se/ha PlotRate Applied Se contentStandard deviation g/ha ppb ppb 277.5 97.5 2 20 236.0 82.6 3 20 251.9 60.5 4 20 229.8 64.5 470.0 138.0 6 40 441.8 81.8
In view of the problems of producing selenium enhanced plants without the associated risk of plant, human or animal toxicity, there has been a need for a convenient, effective method for addressing the problems associated with livestock production in selenillm deficient areas. Specifically,there has been a need for a convenient, effective method of ensllring plant uptake of selenium to produce plants which provide the required levels of selen-ium in animal feed in a consistent, reliable m~nner to enh~nce livestock vitality while ensuring that the plants, ~nim~l~ and handlers are not subjected to toxic levels of selenium.
Furthermore, there has also been a need for a method of supplying selenium to ~nim~lc through the animal feed in order to elimin~te the need for secondary tre~tment of the ~nim~l~ (injection~) while ensuring a constant and consistent supply of selenium in the ~nim~l~' diet.
Furthermore and more specifically, there has been a need for a seed coating technique in which a seed is coated with a seed coating cn~ i.,g selenium that accurately places an exact and ullirollll amount of selenium on each seed and thereafter covered by a water-soluble polymer film that encapsulates the entire seed. There has also been a need for a seed coating 21 6129~
.
technique where the polymer coating is sufficiently resilient to ~r~venl dustingoff so dust borne levels of selenium do not rise to toxic levels during normal h~n(lling of the seed and to prevelll each seed from ending up with non-l.,,irn..,, amount of selenium before pl~nting There has also been a S need for a seed coating technique where a mltrient, fungicide and/or biocide coat may be optionally provided between the seed treatment coat and the polymer film to enhance the early growth of the seed. There has also been a need for coated seeds which hllprove the flow of seeds during h~n-lling.
Seeds of certain crops, such as corn, are routinely treated with fungicides. Accordingly, there has also been a need for a selenium seed-coating technology that incorporates fungicides into the seed coats wherein the seed coats also provide a protective layer thus ren~lçring the fungicide/selenium treated seed safer to handle.
Past seed coating techniques have generally addressed the problems associated with hll~lovillg the growth of plants and have not addressed the problem of enh~n~ ing ~nimal fodder. Examples of soil and seed coating or treatment techniques are found in the prior art. For example, US patent 4,735,015 discloses a seed protective coating using a film forming composition comprisingpolyoxyethylene-polyoxybutylene block co-polymers for controlling water uptake by the seed.
US patent 3,911,183 discloses a seed coating process in which a seed is coated with polymer-pesticide film. Halogenated vinyl resin is used as a film former and pesticide carrier.
US patent 3,698,133 discloses a plant seed with a multiple coating.
The coating is in two layers, an inner porous coating permeable to water and an outer coating of a polymer with a controlled permeability to water. This patent discloses the use of additives to enhance particular functions of the plant.
216129~
US Patent 4,735,017 discloses a coated seed having inorganic additives in the coating.
US Patent 5,017,374 discloses a seed dressing which affords trace elements, such as Zn and Cr to livestock by plant uptake from the coated seeds using fungal spores.
US Patent 5,044,116 discloses a method for polymer coating of seed, which coating may inclllde additives.
US Patent 4,229,613 discloses compositions for the controlled release of trace nutrients into soil including selenium.
C~n~ n Patent Application 2,042,661 discloses a selenium composition for application to soil and pastures. The composition incllltles barium selenate in a slow release form and water-soluble selenium compound.
US Patent 4,388,303 discloses the use of selenium (as selenite absorbed soil) in a plant for repelling foragers by in-1ucing n~llse~
US Patent 4,656,083 discloses the conversion of selçnillm metal to odiferous dimethyl selenide by soil bearing selenium-metabolizing org~ni~m~
for repelling foragers.
US Patent 4,847,087 and 5,169,647 disclose adding selenium from selenium-in-sulfur compositions to soil for plant uptake so that rumin~nt ~nim~ls may receive nutrient selenium.
US Patent 4,880,628 discloses a sustained release composition for livestock having a trace element, for example selenium, in a slowly soluble cement.
' 2161294 SUMMARY OF THE INVENTION
The present invention relates to a seed coating for enh~ncin~ the level of selenium in crops. The invention provides a seed coating, a method of coating a seed, which provides a sufflcient amount of selenium to the seed for uptake, and a coated seed.
In accordance with the invention, a seed coating for enh~ncin~
selenium uptake into a plant is provided comprising:
an abrasion-resistant seed coating m~teri~l; and a sufficient amount of a selenium-cont~inine compound, sufficient to yield a nutritionally required amount of selenium in said plant.
The present invention is further directed to a coated seed for enh~n~n~ selenium uptake into a plant comprising:
a seed and a seed coating composition COlll~)liSillg an abrasion-resistant seed coating material and a sufficient amount of a selenium-co~ e compound, sufficient to yield a n~ltritionally required amount of selenium in said plant.
In one embodiment of the present invention there is provided a coated seed for enhancing selenium uptake into a plant comprising:
a seed and a seed coating composition comprising an abrasion-resistant seed coating polyvinyl acetate homopolymer em~ ion material and a sufficient amount of a selenium-co~ e compound, sufficient to yield 100 to 300 ng of selenium per gram dry weight of said plant.
The present invention is also directed to a method of coating seeds for enhancing selenium uptake into plants comprising the steps of:
a) solubilizing a selenium-collt~illille compound in water to form an aqueous selenium solution;
216I29~
b) mixing the aqueous selenium solution with a liquid polymer em~ ion to form a polymer/selenium solution;
c) mixing the polymer/selenium solution with a sufficient quantity of seeds to form a film coat on the seeds;
d) curing the seeds from step c) to form an abrasion-resistant protective coating on the seeds.
BRIEF DESCRIPIION OF THE DRAWINGS
These and other features of the invention will be more apparent from the following description in which reference is made to the appended drawings wherein:
Figure 1 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenillm content in whole corn grown from the coated seed for a 1991 test plot;
Figure 2 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenium content in whole corn grown from the coated seed for a 1992 test plot;
Figure 3 is a graph showing the linear relationship between the level of selenium in a seed coat of a coated seed and the selenium content in whole corn grown from the coated seed for a 1993 test plot.
DETAILED DESCRIPIION OF THE INVENTION
In accordance with the invention, a seed-coating te~nology is provided which meets the requirements of a selenium-coated seed as set forth above, namely:
1) being non-phytotoxic to the growth of the plant and re(l~ ing the toxic risk to handlers of the seeds;
216129~
2) having a linear and reliable rate response with respect to uptake over the full range of selenium application rates and repeatability from year to year;
3) providing a uniform coating on each seed to ensure consistency between plants, resulting in an effective distribution of selenium within a number of plants;
4) providing an op~ lulll formnl~tion that ensures an efficient uptake of the selenium without wasting or losing selenium to the environment.
In accordance with the present invention, a seed coating incorporating a sufffcient amount of a selenium-cont~ining compound was developed. Said seed coating, when applied to a seed, f~ilitates an enhanced selenium uptake into the plants which develops from said seed.
The amount of the selenium-c~nt~ining compound which is added to the seed coating material is an amount sufffcient to yield a nutritionally required amount of selenium in the resulting plant. The nutritionally required amount of selenium in said resulting plant can range from any amount which is an increase in the plant to, but not in~ tling, an amount which would be deleterious or toxic to the animal upon eating said plant. In general, the target level for selenium in the feed depends on the overall feeding program and safe levels legislated in various countries. Thus, the nutritionally required amount of selenium to which the present invention is directed, can range from 100-400 parts per billion (ppb) (100-400 ng per gram dry weight of said plant). In a further embodiment of the present invention, the nutritionally required amount of selenium in said plant ranges ~om 100-300 ppb.
The sufficient amount of the selenium-collt~illil~g compound which is added to the seed coating material in order to yield the mltrition~lly required amount of selenium in said plants is based on a number of variables. These variables inchllle for example the selenium-co~ ne compound; the seed size; and the number of seeds sown per hectare.
The selenium-co~ il,g compound can be almost any selenium compound, for example salts or oxides of selenillm Typical selenium compounds can include sodium selçn~te, sodium selenite, selenium disulphide, selenium flioxi(le, selenium sulfur oxide, barium selenate, pot~ m selenate, pot~C~i-lm selenite, calcium selenate, r~lcillm selenite, and the like.
In one embodiment of the present invention, the selenium-col-l~ini"g compound is selected from sodium selen~tç, sodium selenite and selenium disulphide.
The absorption ability, or uptake of selenium by the plant will vary from one selenium-cont~inine compound to another. Thus, it will be obvious to persons skilled in the art that if a compound is selected which has a lower absorption ability, then a higher concentration of that selenium-c-ll-t~il,il-e compound would be required in the coating composition to yield the n~ltritionally required amount of selenium in the plant, as defined above.
As by way of an example, in one embodiment of the present invention, sodium selenate is used as the selenium-collt~ lle compound. In this example, the sodium selenate is added to the seed coating composition, so that the final amount of selenium in the soil is between 5 and 50 grams of selenium per hectare.
The amount of selenium-con~ illg compound added to the seed coating material will also vary, as noted above, depending upon the size of the seed and the seed sowing rate. For example, if a high number of seed per hectare is planted, then the amount of selenium-col-L~i,-i.,g compound in the coating composition would be less than for a crop which has a lower 216129~
.
seeding rate. The sowing rate for any particular crop would remain constant.
For example the sowing rate for corn is a~roxi...~tely 75,000 seeds per hectare. Thus, if, when sodium selenate is used as the selenium-co.~ g compound, the amount of selenium in the coating composition for corn would range from 5 to 50 grams per 75,000 seeds or between 5 and 50 grams of selenium per hectare.
In one embodiment of the present invention, where corn is the seed which is coated, and sodium selenate is the selenium-cont~ining compound, to obtain 300 ppb concentration of selenium in the corn plant, 15 to 25 grams of selenium should be added to the seed coat m~teri~l per 75,000 seeds, and more specifically 16 to 21 grams.
The present invention is directed to a selenium-c~ g seed coating composition, which, when said seed coating composition is applied to a seed, will yield a plant with a higher level of selenium. The present invention is directed to a seed coating composition for any type of seed, wherein said resulting plant or part thereof, is used for livestock feed or for human consumption. There is no limitation on the type of seeds which can be used according to the present invention. For example, the present invention is directed to a seed coat composition which can be used to coat seeds for the production of pulse crops, cereal crops, large grain crops, grass crops and other broad leaf crops and the l~e, destined for animal or human consumption.
Accord~-g to the present invention, either the grain of the plant, or the whole plant, can be used as a feed source. There may be some variation between the amount of selenium which is present in the grain as compared to the whole plant. Thus, if it is known that only the grain or the seed of the crop is used as a food source, the amount of selenium-collt~inil~g material used in the coating composition may require adjustment. In all cases, however, the factors discussed above will be selected to ensure that the 216129~
resulting plant, or plant part, which is used as a feedstuff contains a nutritionally required amount of selenium.
According to the present invention, any polymer m~tçri~l can be used in the seed coating composition, as the seed coat m~teri~l There are a number of polymer coating compositions which have been described in the prior art. Any of these materials and methods would be useable in the present invention. Suitable polymer type m~t~ lc have been described in prior art references, of which U.S. Patents 4,251,952, 3,905,152, 5,106,648 and 5,300,127 are examples.
According to the present invention, suitable water soluble coating material can be selected from homopolymers of butylated polyvinylpyrrolidone, poly(vinylpyrrolidone/1 -hexadecene), villyllJyllolidone/styrene copolymers, vil~ yllolidone/vinyl acetate copolymers, alkylatedpolyvillyl~yrrolidone, polyvinyl acetate, polyvinyl acetatehomopolymer emulsions, fully or partially hydrolized polyvinyl alcohol, polyvinyl alcohol homopolymer emulsions, copolymers of vinyl pyrrolidone and vinyl acetate, poly(methyl vinyl ether)maleic anhydride copolymers, vinyl acetate/butyl acrylate compounds, acrylic copolymers, styrene/acrylic ester copolymers vinyl acetate/ethylene copolymers, vinyl acetate/VeoVa 10/butyl acrylate terpolymers and the like. The method of preparing said polymers for use as seed coat material are well known in the art.
In one embodiment of the present invention, an addition~l abrasion-resistant coating is provided as a second outer coating. If only one coat is used, then there will be a certain amount of selenium on the outside of the coating composition and, thus, the seed will still be hazardous to handle. A
second coating will form an abrasion-resistant protective coating on the seeds which will completely encase the selenium irmer coat and, thus, will render the seed safer for h~n(lling purposes. Any of the polymer m~teri~lc which have been described for the irmer coat could be used for the outer coat material.
The seed coating can also contain other materials which are required S or will enhance the germin~tion or growth of the seed. These further materials can include nutrients such as pot~ m, phosphate or nitrogen, biological nutrients, or a biocide inrlnlling fungicides.
In the ex~mple where a two-layered seed coating is used, a drying agent may be added to the seeds once the first seed coat has been applied to ensure water removal from the inner selenillm coat to enhance the storage of the seeds. Any suitable drying agent known in the art can be used for this purpose. For example, a suitable drying agent such as calcium carbonate, calcium oxide, calcium hydroxide, vermiculite, ~ tom~ceous earth, gypsum, talcum, bentonite, kaolin, and various metal silicates can be used.
Any seed coating method can be used accoldhlg to the present invention. In general, abrasion-resistant selenium-coated seeds are prepared by first dissolving the selenium-co.~ g material in water to form a water-selenium solution co~ g a known amount of selenium. The solution is then mixed with a liquid polymer emulsion to form a polymer/selenium solution. A quantity of seeds are then mixed with the polymer/selenium solution to form a film coat on the seeds. The seeds are then cured to form an abrasion-resistant coating on the outer surface of said seeds.
As described above, in one embodiment of the present invention, an additional abrasion-resistant coating is provided on the seeds to protect the handler from the selenium coating m~teri~l In this embodiment, the seeds, after being coated with the polymer/selenium solution, are partially cured and may be mixed with a drying agent, as described above, to form a drying agent coat on the seeds. The drying agent coat may be used to ensure water removal from the inner selenium coat to enhance the storage of the seeds.
~ 2l6l2sa The seeds are then mixed with a second liquid polymer emulsion to form an abrasive-resistant protective co~ting on the seeds. The seeds are then cured.
While this invention is described in detail with particular reference to preferred embodiments thereof, said embodiments are offered to illustrate but not to limit the invention.
EXAMPLES
Example 1- Selenium Seed Coating on Corn Seeds The selenium seed coating was field tested over a three year period in order to investigate the above criteri~ narnely the phytotoxicity of seleniumon the growing plant, the selenium uptake characteristics by the growing plant and the repeatability over several growing seasons in view of the seed coating te~lmiques.
Seed of corn hybrid G4066 (Funk Hybrids) was coated with selenium using a polymer seed coat of a polyvinyl acetate homopolymer emulsion as the seed coat material.
The selenium was added to the seed coat material at a rate of 0, 5, 10, 20 or 40 g of selenium per 75,000 seeds (equivalent to grams of selenium per hectare), in the form of sodium selenate.
The selenium-coated seeds were planted in mid-May to early June on a Monroe series soil (Eutric Eluviated Brunisol), a sandy loam soil known to be low in selenium. Prior to seeding, the field was cultivated and fertilized with 300 kg/ha of nitrogen and 70 kg/ha each of pot~c~inm and phosphorus.
Lime was applied when necessary.
Weeds were controlled pre-emerge with the herbicide Atrazine (1.8 kg/ha). Weeds were also controlled by hand-weeding and post-emerge broadleaf herbicides.
The corn was planted by hand, using corn jabbers, in rows spaced 75 cm apart. Seeding was done in order of increasing selenium concen~l~Lion to ."i~i."i,e cross-cont~min~tion Plants within a row were spaced 18 cm apart to give a final plant population of 75,000 plants/ha.
Each plot consisted of three 1.8 meter long rows. The selenium application rates were randomized within each of four replicates to give a randomized complete block design.
Plants were harvested each year in October. Plots were harvested in order of increasing seleniumrates to "~ i"~i~e cross-cont~min~tion. The entire centre row was harvested (whole plants), weighed, then chopped with a commercial chopping m5~ ine. A represelllaliv~ sample of chopped m~teri~l was taken, weighed and dried to a colLslalll weight. Drying temperature was low (40~C) to minimi7e vol~tili7~tion of selenium. After drying, samples were reweighed, and ground to pass through a 1 mm mesh.
Samples were ground in order of increasing selenium concentration to ", i .~ i ", i,e cross-cont~min~tion.
Selenium analysis was performed by inductively coupled plasma mass spectroscopy (ICPMS) after sample decomposition by rnicrowave digestion.
Five ml of nitric acid and a selenium stable isotope internal standard were added to 0.5 g samples which were digested in sealed Teflon vessels using microwave power. Volatile selenium hydride was generated and the quantity of selenium determined by isotope dilution ICPMS. Accuracy of the determin~tion was verified by use of a certified reference material. The data was analyzed statistically with SAS software using a randomi7e~1 complete block model.
Levels of selenium in the control corn plants were aylJloxi~ tely 2.7-9.1 ppb dry matter in the first sample. These rates are typical for crops grown in coastal British Columbia and other low selenium areas around the world. Applied selenium increased selenium content in the corn in a linear fashion in all trials (see Figures 1-3 and Table 1). Figures 1-3 and Table 1 show that for every 10 g/ha increase in application rate of selenium, as sodium selenate, selerlium c-~ncçntration in corn increased by 120-180 parts per billion. The target level for seleninm in feed depends on the overall feeding program and safe levels leFi~l~ted in various countries. To obtain 300 ppb concentration, which is commorlly considered desirable, 16-21 g selenium/ha should be added to the seed coat. This corresponds to the rates of 10-20 g/ha of selenium commonly applied as fertilizer in New 7e~1~n(1 Based on an average yield of 16.6 tonne/ha, the efficiency of recovery of applied selenium was in the range of 20-33%. Repeatability over the three year trial period is evident from Figures 1 to 3.
' - 216129~
Table 1 Effect of selenium seed coating on yield and selenium uptake in whole crop and grain or corn in 1993 Whole Corn Grain Intended Actual Yield Se Se ~o Se Se rate rate t/hacontent uptake uptake g/ha g/ha ppb g/ha ppb 0 0.0044 18.4 2.7 0.05 -- 6.5 0 + CACO3 0.05 15.8 1.5 0.02 -- not tested 4.4 17.459.1 1.0 22.8 not tested 10.8 17.4167.5 2.8 26.0 not tested 10+CaCO3 12.0 19.5129.5 2.6 21.6 not tested 18.8 16.5288.2 4.7 25.1 193.0 30.7 16.1439.0 6.1 19.9 not tested 35.6 11.4516.9 7.1 19.9 not tested Yield did not appear to be appreciably affected by selenium application except perhaps at 40 g/ha (Table 1). No visual symptoms associated with selenium applications were apparent.
s The percentage of the applied selenium that was taken up by the crop ranged 20-26~o and, accordingly, the percentage of uptake was not affected by selenium application rate.
Selenium concentration in the grain (193 ppb) was lower than in the whole plant (288 ppb) so for selenium enhancement of grain, 50~o more selenium is required in the seed coat.
216129~
The variability of selenium content in individual plants ranged from 25% - 40% of the mean (Table 2). This in~lic~tes that less than 3~o of the plants contained more than 1.8 times of the desired selenium content and further, (lçmonstrates the ulliro~ y of the coating. This seed coating technique provides very few seeds with potentially phytotoxic levels of selenium.
Table 2 Variabilib in the selenium content of individual corn plants at 20 and 40 g Se/ha PlotRate Applied Se contentStandard deviation g/ha ppb ppb 277.5 97.5 2 20 236.0 82.6 3 20 251.9 60.5 4 20 229.8 64.5 470.0 138.0 6 40 441.8 81.8
7 40 678.8 285.1 Accordingly, the following general results were achieved with respect to the above criteria:
s 1. Toxicib The concentrations of selenium around the corn seed coated with selenium during germin~tion is high although difficult to quantify so the effectof the selenium seed coating on the emerging plants could not be predicted.
The results show no reduction in yield to 40 g Se/ha, no reduced germin~tion or emergence, and no visual symptoms of stress.
216129~
2. Linear Rate Response and I~pe~t~bility Very similar rates of uptake in the trials on three sites over 3 years was an unexpected result since growing conditions should effect selenium uptake. A linear rate would probably not occur if the seedling were damaged by the selenium.
3. Uniform Appli-~t;1n The results show that the application tec}mique used was effective in supplying uniform doses of selenium to each seed (Table 2).
4. Distribution of Selenium in the Plant Generally, the results show that the corn grain con~ led less selenium than the whole plant, and, hence for grain production higher rates of seed coating would be required.
5. Optimum Selenium Formulation Other form~ tions of selenium (selenite, sulphide-SeS2) were found to be less readily taken up from the seed coat than selenate. Neither ",i"l"" hydroxide nor calcium carbonate enh~nre-l the uptake of sodium selenate.
6. Uptake The results show that selenium applied in a seed coat is absorbed at a more efficient rate of at least 20% of the quantity applied to the seed compared to other methods. It was unexpected that this seed coating technology would result in the plant uptaking selenium at more efficient rates in comparison with other methods. Thus, less selenium was wasted or lost to the environment.
The terms and expressions which have been employed in this specification are used as terms of description and not of limit~tions, and thereis no intention in the use of such terms and expressions to ey~lllde any 21 61 29q equivalents of the features shown and described or portions thereof but it is recognized that various modiffcations are possible within the scope of the claims.
All scientific publications and patent documents are incorporated herein by reference.
REFERENCES:
Ylaranta, T. 1983 Effect of applied selenite and selenate on the selenium content of barley (Hordeum vlll~re) Ann Agric., Fenn 22: 164-174.
Gupta, U. C. and Maleod SA. 1994 Effect of various sources of seleninm fertilizer on selenium concentration of feed crops. Can J. Soil Sci. 74: 285-290.
Gupta, U.C., MacRae, KB. aml ~nterKA. 1988 Selenium enrichment of crops through foliar applications Can J. Soil Sci. 68: 519-526.
Carlson, C.L., Kaplan D.I. and Adriano, D.C. 1989 Effect of selenillm on germin~ti-~n and radical elongation of selected agronomic species. Ellviro~ ent~l and Experimental Botany 27:
493-698.
Spencer N.E,. and Siegel S.M. 1978 Effect of sulfur and selenium - Hg - toxicity in turnip see germin~tes Water Air Soil Pollut. 9: 423-427.
Levine ~E. 1925 Effect of selenium compounds upon growth and germin~tion in plants Am J. Bot 12: 82-90.
Carlson, C.L., Adriano D.C., and Dixon P.M. 1991 Effects of soil applied selenium to growth and selenium content of a forage species. Envira Quality 20: 363-368.
216129~
Arvy M.P. 1993 Selenated and selenite uptake and translocation in bean plants (Plaseolus vulgaris). Journal of Exp. Botany 44: 1083-1087.
Wu, L. And Huang Z.Z. 1992 Selenium ~c.cimil~tion and nutrient elementuptake inwhite clover and fall fescue under the inflllence of sulphate concentration and selenium tolerance of the plants. Journal of Exp. Bot. 43: 549-555.
Carey E.E. and All~way WH. 1973 Selenium content of field crops grown in selenite treated soils.
Agron J. 65: 922-925.
Hemingway, RG. 1982 Report of a Study Group Commissioned by the Scottish Agricultural Colleges and the Scottish Agricultural Research Institutes, Edinburgh.
Trace Element Deficiency in Ruminants.
Gupta, U. C, Winter, KA. and Kunelius, H.T. 1983 Effect of treating forage seed with selenium on the concentrations of alfalfa and Westerwolds ryegrass. Can J. Soil Sci. 63:641-643.
Stephen, RC, Saville, D.J., and Wathnson J.H. 1989 The effects of sodium selenate applications on growth and selenium concentration in wheat. N. Zeal. J. Crop Hort. Sci. 17:229-237.
s 1. Toxicib The concentrations of selenium around the corn seed coated with selenium during germin~tion is high although difficult to quantify so the effectof the selenium seed coating on the emerging plants could not be predicted.
The results show no reduction in yield to 40 g Se/ha, no reduced germin~tion or emergence, and no visual symptoms of stress.
216129~
2. Linear Rate Response and I~pe~t~bility Very similar rates of uptake in the trials on three sites over 3 years was an unexpected result since growing conditions should effect selenium uptake. A linear rate would probably not occur if the seedling were damaged by the selenium.
3. Uniform Appli-~t;1n The results show that the application tec}mique used was effective in supplying uniform doses of selenium to each seed (Table 2).
4. Distribution of Selenium in the Plant Generally, the results show that the corn grain con~ led less selenium than the whole plant, and, hence for grain production higher rates of seed coating would be required.
5. Optimum Selenium Formulation Other form~ tions of selenium (selenite, sulphide-SeS2) were found to be less readily taken up from the seed coat than selenate. Neither ",i"l"" hydroxide nor calcium carbonate enh~nre-l the uptake of sodium selenate.
6. Uptake The results show that selenium applied in a seed coat is absorbed at a more efficient rate of at least 20% of the quantity applied to the seed compared to other methods. It was unexpected that this seed coating technology would result in the plant uptaking selenium at more efficient rates in comparison with other methods. Thus, less selenium was wasted or lost to the environment.
The terms and expressions which have been employed in this specification are used as terms of description and not of limit~tions, and thereis no intention in the use of such terms and expressions to ey~lllde any 21 61 29q equivalents of the features shown and described or portions thereof but it is recognized that various modiffcations are possible within the scope of the claims.
All scientific publications and patent documents are incorporated herein by reference.
REFERENCES:
Ylaranta, T. 1983 Effect of applied selenite and selenate on the selenium content of barley (Hordeum vlll~re) Ann Agric., Fenn 22: 164-174.
Gupta, U. C. and Maleod SA. 1994 Effect of various sources of seleninm fertilizer on selenium concentration of feed crops. Can J. Soil Sci. 74: 285-290.
Gupta, U.C., MacRae, KB. aml ~nterKA. 1988 Selenium enrichment of crops through foliar applications Can J. Soil Sci. 68: 519-526.
Carlson, C.L., Kaplan D.I. and Adriano, D.C. 1989 Effect of selenillm on germin~ti-~n and radical elongation of selected agronomic species. Ellviro~ ent~l and Experimental Botany 27:
493-698.
Spencer N.E,. and Siegel S.M. 1978 Effect of sulfur and selenium - Hg - toxicity in turnip see germin~tes Water Air Soil Pollut. 9: 423-427.
Levine ~E. 1925 Effect of selenium compounds upon growth and germin~tion in plants Am J. Bot 12: 82-90.
Carlson, C.L., Adriano D.C., and Dixon P.M. 1991 Effects of soil applied selenium to growth and selenium content of a forage species. Envira Quality 20: 363-368.
216129~
Arvy M.P. 1993 Selenated and selenite uptake and translocation in bean plants (Plaseolus vulgaris). Journal of Exp. Botany 44: 1083-1087.
Wu, L. And Huang Z.Z. 1992 Selenium ~c.cimil~tion and nutrient elementuptake inwhite clover and fall fescue under the inflllence of sulphate concentration and selenium tolerance of the plants. Journal of Exp. Bot. 43: 549-555.
Carey E.E. and All~way WH. 1973 Selenium content of field crops grown in selenite treated soils.
Agron J. 65: 922-925.
Hemingway, RG. 1982 Report of a Study Group Commissioned by the Scottish Agricultural Colleges and the Scottish Agricultural Research Institutes, Edinburgh.
Trace Element Deficiency in Ruminants.
Gupta, U. C, Winter, KA. and Kunelius, H.T. 1983 Effect of treating forage seed with selenium on the concentrations of alfalfa and Westerwolds ryegrass. Can J. Soil Sci. 63:641-643.
Stephen, RC, Saville, D.J., and Wathnson J.H. 1989 The effects of sodium selenate applications on growth and selenium concentration in wheat. N. Zeal. J. Crop Hort. Sci. 17:229-237.
Claims (24)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A seed coating composition for enhancing selenium uptake into a plant comprising:
an abrasion-resistant seed coating material; and a sufficient amount of a selenium-containing compound, sufficient to yield a nutritionally required amount of selenium in said plant.
an abrasion-resistant seed coating material; and a sufficient amount of a selenium-containing compound, sufficient to yield a nutritionally required amount of selenium in said plant.
2. The seed coating composition of claim 1, wherein the nutritionally required amount of selenium is up to 400 ppb, based on dry weight of the plant.
3. The seed coating composition of claim 2, wherein the nutritionally required amount of selenium is from 100 to 400 ppb, based on dry weight of the plant.
4. The seed coating composition of claim 3, wherein the nutritionally required amount of selenium is from 100 to 300 ppb, based on dry weight of the plant.
5. The seed coating composition of claim 4, wherein the selenium-containing compound is selected from the group consisting of sodium selenate, sodium selenite, selenium dioxide, selenium disulphide, selenium sulfur oxide, barium selenate, potassium selenate, potassium selenite, calcium selenate, calcium selenite, and the like.
6. The seed coating composition of claim 5, wherein the selenium-containing compound is selected from the group consisting of sodium selenate, sodium selenite and selenium disulphide.
7. The seed coating composition of claim 6, wherein the selenium-containing compound is sodium selenate.
8. The seed coating composition of claim 7, wherein the plants are crop plants selected from the group consisting of a pulse crop, a cereal crop, a large grain crop, a grass crop, other broad leaf crops and the like.
9. The seed coating composition of claim 8, wherein the abrasion-resistant seed coating material is selected from the group consisting of homopolymers of butylated polyvinylpyrrolidone, poly(vinylpyrrolidone/1-hexadecene), vinylpyrrolidone/styrene copolymers, vinylpyrrolidone/vinyl acetate copolymers, alkylated polyvinylpyrrolidone, polyvinyl acetate, polyvinylacetate homopolymer emulsions, fully or partially hydrolized polyvinyl alcohol, polyvinyl alcohol homopolymer emulsions, copolymers of vinyl pyrrolidone and vinyl acetate, poly(methyl vinyl ether)maleic anhydride copolymers, vinyl acetate/butyl acrylate compounds, acrylic copolymers, styrene/acrylic ester copolymers vinyl acetate/ethylene copolymers, vinyl acetate/VeoVa 10/butyl acrylate terpolymers, and the like.
10. The seed coating composition of claim 9, wherein the abrasion-resistant seed coating material is a polyvinyl acetate homopolymer emulsion.
11. A coated seed for enhancing selenium uptake into a plant comprising:
a seed and a seed coating composition comprising an abrasion-resistant seed coating material and a sufficient amount of a selenium-containing compound, sufficient to yield a nutritionally required amount of selenium in said plant.
a seed and a seed coating composition comprising an abrasion-resistant seed coating material and a sufficient amount of a selenium-containing compound, sufficient to yield a nutritionally required amount of selenium in said plant.
12. The coated seed of claim 11, wherein the nutritionally required amount of selenium is up to 400 ppb, based on dry weight of the plant.
13. The coated seed of claim 12, wherein the nutritionally required amount of selenium is from 100 to 400 ppb, based on dry weight of the plant.
14. The coated seed coating of claim 13, wherein the nutritionally required amount of selenium is from 100 to 300 ppb, based on dry weight of the plant.
15. The coated seed of claim 14, wherein the selenium-containing compound is selected from the group consisting of sodium selenate, sodium selenite, selenium dioxide, selenium disulphide, selenium sulfur oxide, barium selenate, potassium selenate, potassium selenite, calcium selenate, calcium selenite, and the like.
16. The coated seed of claim 15, wherein the selenium-containing compound is selected from the group consisting of sodium selenate, sodium selenite and selenium disulphide.
17. The coated seed of claim 16, wherein the selenium-containing compound is sodium selenate.
18. The coated seed of claim 17, wherein the plants are crop plants selected from the group consisting of a pulse crop, a cereal crop, a large graincrop, a grass crop, other broad leaf crops and the like.
19. The coated seed of claim 18, wherein the abrasion-resistant seed coating material is selected from the group consisting of homopolymers of butylated polyvinylpyrrolidone, poly(vinylpyrrolidone/1 -hexadecene), vinylpyrrolidone/styrene copolymers, vinylpyrrolidone/vinyl acetate copolymers, alkylated polyvinylpyrrolidone, polyvinyl acetate, polyvinyl acetatehomopolymer emulsions, fully or partially hydrolized polyvinyl alcohol, polyvinyl alcohol homopolymer emulsions, copolymers of vinyl pyrrolidone and vinyl acetate, poly(methyl vinyl ether)maleic anhydride copolymers, vinyl acetate/butyl acrylate compounds, acrylic copolymers, styrene/acrylic ester copolymers vinyl acetate/ethylene copolymers, vinyl acetate/VeoVa 10/butyl acrylate terpolymers and the like.
20. The coated seed of claim 19, wherein the abrasion-resistant seed coating material is a polyvinyl acetate homopolymer emulsion.
21. The coated seed of claim 20, further comprising an abrasion-resistant polymer film coat which encapsulates the seed coating composition.
22. A coated seed for enhancing selenium uptake into a plant comprising:
a seed and a seed coating composition comprising an abrasion-resistant seed coating polyvinyl acetate homopolymer emulsion material and a sufficient amount of a selenium-containing compound, sufficient to yield 100 to 300 ng of selenium per dry weight of said plant.
a seed and a seed coating composition comprising an abrasion-resistant seed coating polyvinyl acetate homopolymer emulsion material and a sufficient amount of a selenium-containing compound, sufficient to yield 100 to 300 ng of selenium per dry weight of said plant.
23. A method of coating seeds for enhancing selenium uptake into plants comprising the steps of:
a) solubilizing a selenium-containing compound in water to form an aqueous selenium solution;
b) mixing the aqueous selenium solution with a liquid polymer emulsion to form a polymer/selenium solution;
c) mixing the polymer/selenium solution with a sufficient quantity of seeds to form a film coat on the seeds;
d) curing the seeds from step c) to form an abrasion-resistant protective coating on the seeds.
a) solubilizing a selenium-containing compound in water to form an aqueous selenium solution;
b) mixing the aqueous selenium solution with a liquid polymer emulsion to form a polymer/selenium solution;
c) mixing the polymer/selenium solution with a sufficient quantity of seeds to form a film coat on the seeds;
d) curing the seeds from step c) to form an abrasion-resistant protective coating on the seeds.
24. The method of claim 23, further comprising the step of mixing the seeds from step d) with a liquid polymer emulsion to form a further abrasion-resistant protective coating on the seeds.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002161294A CA2161294A1 (en) | 1995-10-24 | 1995-10-24 | Seed coating for enhancing the level of selenium crops |
| CA002188734A CA2188734C (en) | 1995-10-24 | 1996-10-24 | Seed coating for enhancing the level of selenium in crops |
| US08/862,511 US6058649A (en) | 1995-09-11 | 1997-05-23 | Seed coating for enhancing the level of selenium in crops |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002161294A CA2161294A1 (en) | 1995-10-24 | 1995-10-24 | Seed coating for enhancing the level of selenium crops |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2161294A1 true CA2161294A1 (en) | 1997-04-25 |
Family
ID=4156835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002161294A Abandoned CA2161294A1 (en) | 1995-09-11 | 1995-10-24 | Seed coating for enhancing the level of selenium crops |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2161294A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112334005A (en) * | 2018-06-19 | 2021-02-05 | 株式会社可乐丽 | Aqueous seed coating composition |
| WO2023095083A1 (en) | 2021-11-29 | 2023-06-01 | Novaem Bbtrade | Method for obtaining a nitrogen fertilizer enriched with selenium |
-
1995
- 1995-10-24 CA CA002161294A patent/CA2161294A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112334005A (en) * | 2018-06-19 | 2021-02-05 | 株式会社可乐丽 | Aqueous seed coating composition |
| CN112334005B (en) * | 2018-06-19 | 2023-08-29 | 株式会社可乐丽 | Aqueous seed coating composition |
| WO2023095083A1 (en) | 2021-11-29 | 2023-06-01 | Novaem Bbtrade | Method for obtaining a nitrogen fertilizer enriched with selenium |
| FR3129674A1 (en) * | 2021-11-29 | 2023-06-02 | Novaem Bbtrade | METHOD FOR OBTAINING A NITROGEN FERTILIZER ENRICHED WITH SELENIUM |
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