BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to compositions and a method for
treating potted seedlings and also to a method for planting the potted seedlings.
These compositions and method are useful for rearing vegetable seedlings healthily
in nursing trays. It is to be noted that the term "potted seedlings" is used synonymously
with the term "cell seedlings" or "cell mold seedlings" herein. Accordingly, these
terms are interchangeable herein.
b) Description of the Related Art
Rearing of seedlings is extremely important in the cultivation
of vegetables, flowers or ornamental plants. As is mentioned "Seedlings, fifty percent
crop", whether or not seedlings are good until planting often governs the resulting
crop yield and quality.
Each farm has conventionally reared seedlings by itself
while making good use of its own experience and perception. Keeping in step with
a recent decrease in successors and the resulting aging of those engaged in farming,
however, specialization has advanced in farming because of the increasing trend
that many farmers wish to be liberated from the irksomeness in rearing seedlings
and to concentrate on cultivation. A great majority of farmers nowadays purchase
seedlings and plant them, accordingly.
A variety of rearing methods have been investigated for
seedlings. Of these, rearing of seedlings in cells is about to become a principal
rearing technique for seedlings for various reasons. Described specifically, a large
number of seedlings can be reared under control without needing much labor. These
seedlings are light in weight, so that they facilitate handling and provide excellent
transportation convenience. Upon transplanting, they can be handled in much the
same way as conventional seedlings with soil-covered roots, and permit mechanization
of transplanting work.
"Cell seedlings" are regarded as one type of mold seedlings
reared with their rhizosphere rendered identical in volume and shape by using containers
or the like. The term "cell seedlings" as used herein, therefore, means seedlings
the roots of which have been allowed to spread out through rhizosphere within "cells",
which in turn mean small containers or compartments, such that the roots are molded
within the cells as if potted.
In general, cell seedlings of a vegetable or the like are
reared using cell trays in each of which a number of cells are connected together.
In addition to the above-described meritorious features, cell seedlings also have
other features advantageous for the systemization of rearing of seedlings such that
the efficiency of production of seedlings per unit area is high and the use of seedlings
with roots molded as if potted assures high efficiency in planting work such as
transplanting while reducing transplanting injury.
As quality requirements for cell seedlings of vegetables
or the like, they must be healthy, that is, their roots have grown sufficiently
without spindly growth, and they can be expected to achieve sure rooting (establishment)
and growth after transplanting.
SUMMARY OF THE INVENTION
The present inventors have proceeded with a variety of
investigations to provide cell seedlings of the above-described quality. As a result,
they have found that this object can be achieved by treating seedlings, which are
under rearing in cells, with a treatment agent in which activated carbon is finely
dispersed in water, leading to the completion of the present invention.
In one aspect of the present invention, there is thus provided
a treatment agent for cell seedlings, which comprises water, a dispersant, and activated
carbon finely dispersed with the dispersant in the water.
In another aspect of the present invention, there is also
provided a method for treating cell seedlings, which comprises dipping the cell
seedlings in the treatment agent and/or irrigating the cell seedlings with the treatment
agent.
In a further aspect of the present invention, there is
also provided a method for planting cell seedlings, which comprises pre-treating
the cell seedlings by the treatment method. The thus-planted seedlings may be irrigated
with the treatment agent.
The treatment agent and method according to the present
invention allow cell seedlings, which are under rearing, to grow healthily and after
planting, can promote their rooting and growth. The planting method according to
the present invention can provide cell seedlings with good rooting and growth after
planting.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The present invention will hereinafter be described in
further detail.
Cell seedlings to which the present invention is applied
are seedlings of vegetables, flowers or ornamental plants. No particular limitation
is imposed on their species.
No particular limitation is imposed on the activated carbon
employed in the treatment agent of the present invention for cell seedlings. Illustrative
is one produced by carbonizing a raw material such as charcoal, wood, sawdust, animal
bones, coconut shells or coal and activating the carbonized product with a chemical
or steam. Also usable are those commercially available as powdered carbon, one obtained
by grinding granular carbon, and fibrous carbon.
Activated carbon is porous carbon with a number of minute
pores inside thereof, has a very large internal surface area, and is equipped with
function to adsorb a variety of molecules. By attraction (van der Waales force)
of carbon atoms inside the activated carbon, various molecules are adsorbed and
held.
The treatment agent according to the present invention
for cell seedlings of a vegetable or the like is a dispersion obtained by finely
dispersing activated carbon with a dispersant in water. The content (concentration)
of the activated carbon in the aqueous dispersion is not particularly limited, but
may range from 1 to 50 wt.%, more preferably from 10 to 30 wt.% on the basis of
the whole weight of the aqueous dispersion. If the content is lower than the above
range, the treatment agent may achieve neither sufficient healthy growth [sufficient
growth of roots and stems (without spindly growth)] of cell seedlings nor satisfactory
post-planting rooting and growth. Even if the content is higher than the above range,
on the other hand, the advantageous effects cannot be brought about as much as such
a high content. Such a high content is not only uneconomical but also detrimental
to the stability of the dispersion.
The activated carbon is dispersed with the dispersant in
water. No particular limitation is imposed on the dispersant for use in the present
invention, insofar as it is excellent in the dispersing effect for activated carbon
and has no problem in safety and health. Examples of the dispersant can include,
but are not limited to, anionic surfactants, cationic surfactants, nonionic surfactants,
and silica sol. No particular limitation is imposed on the amount of the dispersant
to be used, although it is preferred to use the dispersant in such an amount that
its concentration in the dispersion falls within a range of from 0.01 to 20 wt.%
(based on the whole weight of the aqueous dispersion). Upon treating cell seedlings,
the treatment agent according to the present invention may be used after diluting
it to an adequate concentration.
To disperse the activated carbon in water, a conventionally-known
dispersing apparatus such as a beads mill or sand mill can be used. The activated
carbon may preferably be dispersed such that their average particle size in the
dispersion is reduced to 100 µm or smaller.
The treatment of cell seedlings with the aqueous dispersion
of activated carbon can be performed, for example, by dipping the cell seedlings
in the aqueous dispersion of activated carbon (hereinafter called "dipping"), irrigating
the cell seedlings with the aqueous dispersion of activated carbon, or using these
dipping and irrigation methods in combination. The treatment method is, however,
not limited to these methods, and no particular limitation is imposed on the treatment
method insofar as it can assure sufficient contact between roots of cell seedlings
and the aqueous dispersion.
The treatment agent according to the present invention
for cell seedlings is effective for the healthy growth of the cell seedlings (for
the promotion of rooting, especially for the formation of many hairy and small roots)
until planting and also for the promotion of rooting (establishment) and growth
after planting.
Before planting, the treatment agent can be used, for example,
by irrigating soil with it before seeding or irrigating the soil with it shortly
after the seeding and further irrigating the soil with it as needed after the seeding
until the planting. Upon planting, it is preferred to plant the cell seedlings,
for example, after dipping them in the treatment agent or irrigating the rhizosphere
with the treatment agent. After planting, on the other hand, it is preferred to
irrigate the treatment agent to planting furrows as needed.
The present invention will next be described more specifically
based on Examples and Comparative Examples, in which all designations of "part"
or "parts" and "%" are on a weight basis.
Example 1 & Comparative Example 1
Powdered activated carbon ("TAIKO ACTIVATED CARBON S",
trade name; product of Futamura Chemical Industries Co., Ltd.) (25 parts), an anionic
surfactant ("DEMOL P", trade name; product of Kao Corporation) (2.5 parts) and water
(72.5 parts) were dispersed in a beads mill until the average particle size of the
activated carbon was reduced to 10 µm or smaller. A cell seedling treatment
agent A was obtained.
On June 1, 1999, cell seedlings of asparagus (2-year-old
seedlings reared in 9 cm pots were used) were treated by dipping them for 30 minutes
in a treatment bath of a 25-fold dilution of the cell seedling treatment agent A,
and were then pulled out of the treatment bath. Those treated cell seedlings were
reared until November 26, 1999. The results of a comparison in growth between the
treated cell seedlings and untreated cell seedlings are presented as averages per
seedling in Table 1.
Table 1
Example 1
Comp. Ex. 1
Number of stems
20.0
15.7
Number of storage roots
176
113
Weight of subterranean part (g)
663
357
Number of small scales
8.3
4.0
As is readily envisaged from Table 1, the growth of cell
seedlings of asparagus is promoted by dipping treatment in an aqueous dispersion
of activated carbon.
Example 2 & Comparative Example 2
On May 26, 2000, 2-year-old asparagus seedlings potted
in 9 cm pots were dipped for 20 minutes in a 25-fold dilution of the cell seedling
treatment agent A of Example 1 such that each seedling was soaked with 100 mL of
the treatment solution, and the potted seedlings were then pulled out of the treatment
solution. Shortly after that, they were planted in a field to be described below.
For some of the seedlings so planted, the soil with the seedlings planted therein
was irrigated with the above-described dilution (irrigated amount: 400 mL per seedling).
357 seedlings were planted as shown below.
Details of treatment
Number of seedlings
Dipping treatment
209
Dipping treatment, and post-planting irrigation
119
Untreated
29
Total
357
The cell seedlings treated as described above were planted
at plant-missing points in a field of asparagus plants in the 6th years
of open-field culture after planting (7 ares, inter-raw spacings : 1.8 m, in-raw
spacings: 35 cm, missing plant rate: 33.2%). On December 8, 2000, 10 plants in each
experimental plot were examined at both aerial parts and subterranean parts thereof.
The untreated seedlings were also planted and examined likewise. Experimental plots
and details of the corresponding treatments are summarized in Table 2. The results
are presented in Table 3.
Table 2
Experimental plot
Details of treatment
Ex. 2
1
Dipping (shortly before planting)
2
Dipping (shortly before planting)
Dipping (shortly before planting)
3
+
Soil irrigation (after planting)
Dipping (shortly before planting)
4
+
Soil irrigation (after planting)
Comp. Ex.2
1
Untreated (irrigated with 400 mL water after
planting)
2
Untreated (irrigated with 400 mL water after
planting)
Table 3
Experimental plot
Number of productive stems
Number of non-productive stems
Effective plant length (cm)
Weight of stems and sterns (g)
Dry weight of stems and sterns (g/plant)
Brix (%)
Weight of roots (g)
Sheltered cultivation
1
1.9
15.9
120
100.0
84.0
20.1
676
1*
0.7
10.6
91
74.0
59.0
15.6
640
Open-field cultivation
2
2.0
10.1
101
41.0
30.0
16.9
232
3
2.0
9.4
108
70.0
50.0
21.0
528
4
2.4
8.7
112
50.0
35.0
17.4
276
2*
0.9
5.9
86
35.0
19.5
17.8
196
* Comparative Example
