U.S. patent application number 10/231983 was filed with the patent office on 2003-03-13 for gel-coated seed.
Invention is credited to Nishiyama, Yuugo.
Application Number | 20030046865 10/231983 |
Document ID | / |
Family ID | 19097198 |
Filed Date | 2003-03-13 |
United States Patent
Application |
20030046865 |
Kind Code |
A1 |
Nishiyama, Yuugo |
March 13, 2003 |
Gel-coated seed
Abstract
A gel-coated seed is provided, which has sufficient strength for
handling just after the production thereof and after the recovery
following the storage under drying, and has a good property in
terms of standing-up of seedling. The gel-coated seed includes: a
seed of a plant; a coating gel-layer, which coats the seed,
consisting of alginic acid-based aqueous gel gelled in the presence
of a multivalent metal ion; and grains consisting of
water-containing hydrophilic polymer, which is resistant to the
multivalent metal ion, distributed in the coating gel-layer.
Inventors: |
Nishiyama, Yuugo; (Hyogo,
JP) |
Correspondence
Address: |
BAKER & DANIELS
111 E. WAYNE STREET
SUITE 800
FORT WAYNE
IN
46802
|
Family ID: |
19097198 |
Appl. No.: |
10/231983 |
Filed: |
August 30, 2002 |
Current U.S.
Class: |
47/57.6 |
Current CPC
Class: |
A01C 1/06 20130101 |
Class at
Publication: |
47/57.6 |
International
Class: |
A01C 001/06; A01C
021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 7, 2001 |
JP |
2001-271729 |
Claims
What is claimed is:
1. A gel-coated seed comprising: a seed of a plant; a coating
gel-layer, which coats the seed, consisting of alginic acid-based
aqueous gel gelled in the presence of a multivalent metal ion; and
grains consisting of water-containing hydrophilic polymer, which is
resistant to the multivalent metal ion, distributed in the coating
gel-layer.
2. The gel-coated seed according to claim 1, wherein the
hydrophilic polymer is a carboxymethylcellulose-based hydrophilic
polymer.
3. The gel-coated seed according to claim 1 or 2, wherein the
multivalent metal ion is a calcium ion.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a gel-coated seed.
[0003] (2) Description of the Related Art
[0004] The gel-coated seed technology (i.e., technology of coating
seeds with gel) improves a conventional labor-intensive agriculture
including excessive sowing in the field taking low gemmation rate
of seeds into consideration, that is, taking the fact that the bud
barely or hardly comes out from the coating gel-layer after the
gel-coated seed germinates, and thinning out after gemmation.
[0005] The technology is an epoch-making technology, by which a
seedling can securely be obtained from a grain of seed with the aid
of water or other constituent contained in a coating gel-layer and
furthermore a crop can be obtained. The technology enables the use
of F1 seeds, which is excellent and very expensive, thereby
attaining significant improvement in yield and quality. The
technology is really good news for Japanese agriculture, which
should survive in the condition that high quality and cheap
vegetables and flowers are imported from neighboring Asian
countries.
[0006] At the beginning, the coating gel-layer of the-gel-coated
seed was composed of only alginic acid-based aqueous gel. However,
since the alginic acid-based aqueous gel is relatively hard, such a
gel-coated seed had a problem in terms of "standing-up of seedling"
(explained below). In other words, since the alginic acid-based
aqueous gel is relatively hard, the bud of a coated plant may
become difficult to grow or may not come out from the coating
gel-layer to die. Consequently, such a measure has been employed
that grains consisting of hydrophilic polymer and water are
distributed in the coating gel-layer.
[0007] In this specification, the "standing-up of seedling" is
defined as a condition that a gel-coated seed sown in a field
germinates, the bud comes out from the coating gel-layer and
further comes out from the soil of the field, and it becomes a
defect-free plant body with the first leaf thereof being completely
out (i.e., being completely extends). A ratio (%) of seeds, each of
which has a good property in terms of "standing-up of seedling"
described above, relatively to all seeds sown is called "ratio of
standing-up of seedling" in this specification.
[0008] The gel-coated seed, in which grains consisting of
water-containing hydrophilic polymer are distributed in the coating
gel-layer consisting of alginic acid-based aqueous gel, is
produced, for example, by the following manner.
[0009] A weighing is carried out so that the concentration of
sodium alginate becomes 0.9 wt % and the final concentration of
powdered starch polyacrylate-based hydrophilic polymer (i.e.,
starch-acrylic acid graft polymer) becomes 0.2 wt %, then water is
added thereto so as to dissolve the sodium alginate sufficiently.
At that time, the hydrophilic polymer absorbs water to be granular
and is dispersed by stirring. By using this liquid dispersion
(i.e., gel-forming liquid in which the grains consisting of the
water-containing hydrophilic polymer are dispersed), a droplet
thereof is formed at a lower end of a hollow tube, into which a
seed is introduced from the interior of the hollow tube, and then
the resultant droplet is dropped in a solution containing
multivalent metal ion having concentration of 12-14 wt % such as an
aqueous solution (hardening liquid) of calcium chloride, thereby
obtaining a gel-coated seed including a coating gel-layer, which is
insolubilized against water.
[0010] Since the strength of thus produced coating gel-layer is
very strong, in order to attain a better property in terms of
standing-up of seedling, a gel-coated seed having low concentration
of alginate has been produced, by which a three-dimensional network
structure obstructing the growth of the seed due to the alginic
acid in the coating gel-layer is weakened.
[0011] In such a case, however, since the strength of the coating
gel-layer is deteriorated, when a hopper is used upon handling of
the gel-coated seeds such as mechanical sowing, the gel-coated seed
is crushed and deformed causing the hopper stuck and otherwise the
surface layer of the gel-coated seed comes off causing the
mechanical sowing unable to be carried out, that is, handling
property thereof is deteriorated and the originally intended effect
for the gel-coated seed cannot be attained.
[0012] Therefore, in order to attain sufficient strength of the
coating gel-layer in such a condition that the using amount of the
alginate is reduced, the amount of the hydrophilic polymer is
significantly increased.
[0013] By this measure, the coating gel-layer having sufficient
strength in usual use is obtained. However, when the coating
gel-layer is dried for the purpose of storing the gel-coated seed
and thereafter the coating gel-layer is provided with water for
sowing the gel-coated seed, the coating gel-layer is not
sufficiently recovered, that is, the coating gel-layer becomes
spongy deteriorating its strength significantly and the gel-coated
seed thus obtained becomes hard to be handled.
SUMMARY OF THE INVENTION
[0014] It is therefore an objective of the present invention to
solve the above problem and to provide a gel-coated seed, which has
sufficient strength for handling just after the production thereof
and after the recovery following the storage under drying, and has
a good property in terms of standing-up of seedling.
[0015] The inventor has carried out investigation on a starch
polyacrylate-based hydrophilic polymer conventionally employed for
attaining the objective described above. As a result, the inventor
has found that when a hydrophilic polymer once contained water is
dried and recovered by absorbing water, the hydrophilic polymer
coming in contact with a multivalent metal ion (i.e., gelling
agent) hardly absorbs water and hardly recovers, that is, upon
absorbing water and recovering of the coating gel-layer of the
gel-coated seed, only the three-dimensional network structure
portion due to the alginic acid is recovered causing the coating
gel-layer to be spongy, therefore the strength necessary for the
coating gel-layer cannot be obtained.
[0016] In order to attain the above objective, the present
invention is to provide a gel-coated seed comprising: a seed of a
plant; a coating gel-layer, which coats the seed, consisting of
alginic acid-based aqueous gel gelled in the presence of a
multivalent metal ion; and grains consisting of water-containing
hydrophilic polymer, which is resistant to the multivalent metal
ion, distributed in the coating gel-layer.
[0017] With the construction described above, the gel-coated seed
of the present invention significantly well recovers upon absorbing
water after the storage under drying in comparison with a
conventional gel-coated seed proposed in, for example, Japanese
Patent Application Laid-Open No. H5-56707, even when the amount of
the hydrophilic polymer is increased. Moreover, just after the
production thereof and after the recovery following the storage
under drying, the gel-coated seed of the present invention has
sufficient strength for handling and a good property in terms of
standing-up of seedling.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] In the present invention, the multivalent metal ion, which
forms the alginic acid-based aqueous gel, is a metal ion having a
valence equal to or higher than two and is not a heavy metal ion.
The multivalent metal ion is, for example, calcium ion, aluminum
ion, and iron ion.
[0019] In the present invention, the hydrophilic polymer that is
resistant to the multivalent metal ion means such a hydrophilic
polymer that if the multivalent metal ion is, for example, a
calcium ion, a hydrophilic polymer grain, which absorbs water in a
sodium alginate aqueous solution of 0.9 wt % concentration so as to
be granular, is immersed in a calcium chloride aqueous solution of
20 wt % concentration and taken out therefrom by filtration after
one minute, wherein the weight change of the hydrophilic polymer is
not more than 10%. Here, the weight change means a change in weight
of the hydrophilic polymer, which is expressed by an absolute
value, before and after the contact of the hydrophilic polymer with
the calcium chloride aqueous solution.
[0020] If the weight change of the hydrophilic polymer is more than
10%, the recovery property of the gel-coated seed after the storage
under drying is deteriorated and therefore, the effect of the
present invention cannot be attained.
[0021] The hydrophilic polymer that is resistant to the multivalent
metal ion is, for example, a sulfonic-based hydrophilic polymer,
nonionic-based hydrophilic polymer, and
carboxymethylcellulose-based hydrophilic polymer. Especially, a
carboxymethylcellulose-based hydrophilic polymer is preferable
since it is not toxic and is biodegradable, causing no problem in
terms of the pollution of the environment.
[0022] Other than these hydrophilic polymers described above, for
example, as for a starch polyacrylate-based hydrophilic polymer,
hydrophilic groups in the polymer crosslink with each other by a
calcium ion and therefore, the polymer shrinks and cannot absorb
water again.
[0023] The calcium ion-resistant hydrophilic polymer is normally
added thereto so that the concentration thereof becomes equal to
0.2 wt %. However, in order to attain a better property in terms of
standing-up of seedling, the concentration thereof is preferably
0.5-0.8 wt %. As for the gel-coated seed of the present invention,
even when the using amount of the hydrophilic polymer is increased
as in the latter case, the gel-coated seed has high strength and
excellent handling property just after the formation of the coating
gel-layer, and such high strength and excellent handling property
can be completely recovered by absorbing water after the storage
under drying.
[0024] Further, when the using amount of the calcium ion-resistant
hydrophilic polymer is set to be 0.5-0.8 wt %, tolerance of the
concentration of the calcium chloride aqueous solution as the
hardening liquid extends.
[0025] So far, strict control has been necessary for the
concentration of the calcium chloride aqueous solution, which has
been used for producing a conventional gel-coated seed (including a
gel-coated seed, in which grains consisting of water-containing
hydrophilic polymer are distributed in a coating gel-layer
consisting of alginic acid-based aqueous gel).
[0026] That is, if the concentration of the calcium chloride
aqueous solution is lower than 12 wt %, the strength of the
gel-coated layer becomes too weak to handle, causing a problem that
the mechanical sowing cannot be carried out. On the other hand, if
the concentration of the calcium chloride aqueous solution is
higher than 14 wt %, the gel-coated seed cannot recover
sufficiently, and the bud hardly comes out from the coating
gel-layer after the gel-coated seed germinates. This has been a
reason why the concentration of the calcium chloride aqueous
solution must be controlled in the narrow range of 12-14 wt %. This
concentration gradually decreases as the manufacturing number of
the gel-coated seed increases. Further, this concentration changes
depending upon the vaporization of water. Thus, since the range of
the concentration to be usable is very narrow, the concentration
has to be controlled strictly even if the concentration is
controlled by the density of the solution.
[0027] However, if the using amount of the calcium ion-resistant
hydrophilic polymer is set to be 0.5-0.8 wt % upon formation of the
aqueous gel-forming solution, the coating gel-layer having suitable
hardness can be obtained when the concentration of the calcium
chloride aqueous solution as the hardening liquid is 10-20 wt %.
Thus, the usable concentration range of the calcium chloride
aqueous solution becomes wider, especially at the high
concentration side, as a result, the control of the concentration
becomes easy to be carried out, thereby making the quality control
easier.
[0028] The concentration of sodium alginate is set to be 0.9-1.3 wt
% in the gel-forming solution, in which the grains consisting of
water-containing hydrophilic polymer are dispersed.
[0029] When the using amount of the calcium ion-resistant
hydrophilic polymer is set to be 0.5-0.8 wt %, the concentration of
sodium alginate can be reduced to be 0.5-0.6 wt % in the
gel-forming solution, by which the gel-coated seed to be obtained
has an excellent property in terms of standing-up of seedling, and
excellent strength and handling property just after the formation
of the coating gel-layer and after the recovery by absorbing water
following the storage under drying.
[0030] The gel-coated seed of the present invention can be produced
in a similar manner to that of a conventional gel-coated seed
except for a point that the kind of the hydrophilic polymer is
different from that of the conventional gel-coated seed.
[0031] The gel-coated seed thus prepared can be stored by drying
them for a long period of time so that they can be sown in a
necessary place at a necessary time.
[0032] The drying is carried out at relatively low temperature,
preferably at ordinary temperature, so that the seed is not
damaged. However, if the drying takes a long period of time, the
seed in the gel-coated seed may undesirably germinate. Therefore,
the period of time for drying is preferably shortened by using
ventilation. The gel-coated seed thus dried is stored at ordinary
temperature or under cooling.
[0033] The coating gel-layer is recovered by immersing the
gel-coated seed in water or by the other methods before sowing. It
usually takes 3-16 hours to be recovered depending upon temperature
and the thickness of the coating gel-layer.
[0034] In the recovery, the diameter of the gel-coated seed
principally becomes uniform and the shape thereof recovers its
spherical shape. If the recovered gel-coated seed is spherical
having a diameter of 70-170 relatively to a diameter of 100 for the
gel-coated seed before drying and the uniformity of the diameter
among the gel-coated seeds is good, the gel-coated seed can be
mechanically sown by replacing a grating of a sowing machine. In
general, if the recovered gel-coated seed is too small in diameter,
the bud cannot come out from the coating gel-layer because the
gel-coated layer is hard, on the other hand, if the gel-coated seed
is too large in diameter, the gel-coated seed is soft and does not
have necessary strength, therefore they cannot be handled with a
hopper.
EXAMPLES
[0035] In the following, the gel-coated seed of the present
invention will be explained in detail with examples and comparative
examples.
Comparative Example 1
[0036] Sodium alginate and powdered starch polyacrylate-based
hydrophilic polymer (hereinafter, polymer A) were weighed so that
each concentration in a solution became 0.9 wt % and 0.2 wt %,
respectively and stirred well with adding water. The
water-containing hydrophilic polymer grain dispersed in a
gel-forming solution was observed with a microscope revealing that
the diameter of the grain was 0.1-0.2 mm and the average diameter
was 0.15 mm.
[0037] By using this dispersion solution, its droplet was formed at
a lower end of a hollow tube, then a seed of a long onion was
introduced into the droplet from the interior of the hollow tube
and then, the droplet was dropped in calcium chloride aqueous
solutions (hardening liquids) having the calcium chloride
concentrations of 10, 12, 14, and 16 wt %, thereby preparing
gel-coated seeds (189 seeds per each solution), in which grains
consisting of water-containing hydrophilic polymer were distributed
in a coating gel-layer consisting of alginic acid-based aqueous
gel. The prepared gel-coated seed was approximately spherical
having a diameter of about 1 cm (hereinafter, the same).
[0038] As for the gel-coated seed, which was prepared by using the
hardening liquid of 10 wt % calcium chloride concentration,
apparently had a soft coating gel-layer and could not be handled
with a hopper. On the other hand, as for the gel-coated seed, which
was prepared by using the hardening liquid of 16 wt % calcium
chloride concentration, the coating gel-layer was too hard,
therefore it was considered that the bud could not come out from
the coating gel-layer.
[0039] Consequently, as for the gel-coated seeds, which were
prepared by using the hardening liquids of 10 and 16 wt % calcium
chloride concentration, the further investigation was not carried
out.
[0040] The gel-coated seeds, which were prepared by using the
hardening liquids of 12 and 14 wt % calcium chloride concentration,
were once dried with ventilation and thereafter immersed in water
at room temperature for 7 hours so as to recover the coating
gel-layer.
[0041] At this time, each recovered gel-coated seed was spherical
having weight of 120-148 relatively to weight of 100 for the
gel-coated seed before drying and the uniformity among the
gel-coated seeds was excellent. The recovered gel-coated seed was
free from peeling of its surface and crack, and the diameter
thereof was increased by only about 10% at most. (Hereinafter, the
recovery of the level as described above is defined as
"satisfactory".)
[0042] Further, the rupture stress (breaking stress) was measured
and the result revealed that the recovered gel-coated seed was
suitable to handling with a hopper and it appeared that the bud
could come out from the coating gel-layer. Consequently, the ratio
of standing-up of seedling was investigated.
Comparative Example 2
[0043] In order to improve the ratio of standing-up of seedling,
the amount of the polymer A was increased compared with Comparative
Example 1. That is, sodium alginate and the polymer A were weighed
so that each concentration in a solution became 0.9 wt % and 0.8 wt
%, respectively and stirred well with adding water. The
water-containing hydrophilic polymer grain dispersed in a
gel-forming solution was observed with a microscope revealing that
the diameter of the grain was 0.1-0.2 mm and the average diameter
was 0.15 mm.
[0044] Similarly to Comparative Example 1, by using this dispersion
solution, its droplet was formed at a lower end of a hollow tube,
then a seed of a long onion was introduced into the droplet from
the interior of the hollow tube and then, the droplet was dropped
in calcium chloride aqueous solutions (hardening liquids) having
the calcium chloride concentrations of 10, 12, 14, and 16 wt %,
thereby preparing gel-coated seeds (189 seeds per each solution),
in which grains consisting of water-containing hydrophilic polymer
were distributed in a coating gel-layer consisting of alginic
acid-based aqueous gel.
[0045] Similarly to Comparative Example 1, the gel-coated seeds,
which were prepared by using the hardening liquid of 10 and 16 wt %
calcium chloride concentration, apparently were not suitable for
use, therefore the further investigation was not carried out as to
these gel-coated seeds.
[0046] The gel-coated seeds, which were prepared by using the
hardening liquids of 12 and 14 wt % calcium chloride concentration,
were once dried with ventilation and thereafter immersed in water
at room temperature for 7 hours so as to recover the coating
gel-layer.
[0047] However, the recovered coating gel-layer was spongy and
therefore the gel-coated seed did not have strength large enough to
be handled with a hopper or to be sown by using an automatic sowing
machine. Consequently, the further investigation was not carried
out as to these gel-coated seeds.
Example 1
[0048] An investigation was carried out using the same procedure as
in Comparative Example 1 except for a point that a powdered
carboxymethylcellulose-based hydrophilic polymer (hereinafter,
polymer B) was employed instead of the polymer A. That is, sodium
alginate and polymer B were weighed so that each concentration in a
solution became 0.9 wt % and 0.2 wt %, respectively and stirred
well with adding water. The water-containing hydrophilic polymer
grain dispersed in a gel-forming solution was observed with a
microscope revealing that the diameter of the grain was 0.1-0.2 mm
and the average diameter was 0.15 mm.
[0049] The grain of the hydrophilic polymer B, which absorbed water
in a sodium alginate aqueous solution of 0.9 wt % concentration so
as to be granular, was immersed in a calcium chloride aqueous
solution of 20 wt % concentration and taken out therefrom by
filtration after one minute, then the weight change of the
hydrophilic polymer was measured. The weight decreased by 5%.
[0050] By using this dispersion solution, its droplet was formed at
a lower end of a hollow tube, then a seed of a long onion was
introduced into the droplet from the interior of the hollow tube
and then, the droplet was dropped in calcium chloride aqueous
solutions (hardening liquids) having the calcium chloride
concentrations of 10, 12, 14, and 16 wt %, thereby preparing
gel-coated seeds (189 seeds per each solution), in which grains
consisting of water-containing hydrophilic polymer were distributed
in a coating gel-layer consisting of alginic acid-based aqueous
gel.
[0051] As for each gel-coated seed thus prepared, the coating
gel-layer had strength large enough to be handled and it appeared
that the bud could come out from the coating gel-layer. Therefore,
additional gel-coated seeds (112 seeds per each solution) were
prepared similarly, in which the calcium chloride concentration was
8 and 20 wt %. As a result, the gel-coated seed of the calcium
chloride concentration of 8 wt % was not suitable to be handled and
therefore the further investigation was not carried out. On the
other hand, the gel-coated seed of the calcium chloride
concentration of 20 wt % was appeared to have sufficient strength
to be handled in spite of its high hardness a little and its
recovered condition by absorbing water after drying was appeared to
be in a sufficient level, therefore its ratio of standing-up of
seedling was investigated.
Example 2
[0052] An investigation was carried out using the same procedure as
in Comparative Example 2 except for points that the polymer B was
employed instead of the polymer A and that the calcium chloride
concentrations of 8, 10, 12, 14, 16 and 20 wt % were used. The
gel-coated seeds (112 seeds per each solution) were prepared. (The
water-containing hydrophilic polymer grain dispersed in a
gel-forming solution was observed with a microscope revealing that
the diameter of the grain was 0.1-0.2 mm and the average diameter
was 0.15 mm.)
[0053] The gel-coated seed of calcium chloride concentration of 8
wt % was not apparently suitable to be handled. Therefore, the
other gel-coated seeds except it were subjected to the recovery by
absorbing water after drying. As a result, each recovered condition
was appeared to be in a sufficient level, therefore each ratio of
standing-up of seedling was investigated.
Example 3
[0054] An investigation was carried out using the same procedure as
in Example 2 except for a point that sodium alginate was weighed so
that its concentration in a solution became 0.5 wt % instead of 0.9
wt %. The gel-coated seeds (112 seeds per each solution of the
calcium chloride concentrations of 8, 10, 12, 14, 16 and 20 wt %)
were prepared. (The water-containing hydrophilic polymer grain
dispersed in a gel-forming solution was observed with a microscope
revealing that the diameter of the grain was 0.1-0.2 mm and the
average diameter was 0.15 mm.)
[0055] The gel-coated seed of calcium chloride concentration of 8
wt % was not apparently suitable to be handled. Therefore, the
other gel-coated seeds except it were subjected to the recovery by
absorbing water after drying. As a result, each recovered condition
was appeared to be in a sufficient level, therefore each ratio of
standing-up of seedling was investigated.
Comparative Example 3
[0056] Further, gel-coated seeds were prepared in such a manner
that sodium alginate was weighed so that its concentration in a
solution became 0.5 wt %, and the concentration of the polymer A
dispersed in the solution became the same (0.8 wt %) as that of
Comparative Example 2.
[0057] As a result, the gel-coated seed having sufficient hardness
high enough to be handled was not obtained for each solution of the
calcium chloride concentrations of 8-20 wt %. Consequently, the
further investigation was not carried out as to these gel-coated
seeds.
[0058] (Investigation on Ratio of Standing-up of Seedling)
[0059] The ratio of standing-up of seedling was investigated as to
the gel-coated seed (gel-coated seed of a long onion), in which the
grains consisting of the water-containing hydrophilic polymer are
distributed in the coating gel-layer consisting of alginic
acid-based aqueous gel. The result is shown in Table 1.
1TABLE 1 Concentration Concentration Ratio of Hydro- of of
hardening standing-up of philic sodium alginate liquid seedling
Polymer (wt %) (wt %) (%) Comparative A 0.9 12 61.6 Example 1 14
58.0 10 62.5 12 60.7 Example 1 B 09 14 61.6 16 58.9 20 54.5 10 63.4
12 63.4 Example 2 B 0.9 14 61.6 16 61.6 20 59.8 10 86.6 12 88.4
Example 3 B 0.5 14 89.3 16 87.5 20 88.4
[0060] The examples and comparative examples described above reveal
that as for the gel-coated seed of the present invention, the
coating gel-layer can be completely recovered after the storage
under drying even when the amount of the hydrophilic polymer is
increased, and the ratio of standing-up of seedling can be
significantly improved by reducing the concentration of alginic
acid. Moreover, the gel-coated seed of the present invention is
significantly advantageous in controlling the production of the
gel-coated seed because the tolerance range of the concentration of
the hardening liquid can be broad, whereas a very strict control of
the concentration has been needed conventionally. Furthermore, the
gel-coated seed of the present invention can be precisely sown by
mechanical sowing.
[0061] The aforementioned preferred embodiments are described to
aid in understanding the present invention and variations may be
made by one skilled in the art without departing from the spirit
and scope of the present invention.
* * * * *