CA1244240A - Method of hydroponically growing plant sprouts and apparatus therefor - Google Patents

Abstract

METHOD OF HYDROPONICALLY GROWING PLANT
SPROUTS AND APPARATUS THEREFOR
Abstract of the Disclosure A floating bed useful for hydroponically germinating seeds of a plant and growing the germinated sprouts thereon. The floating bed is floatable by itself on water and includes a pad formed of a hydrophobic material such as foamed polystyrene and provided with one or more through holes. The through holes have a size so that it can continually retain water therein by capillary attraction during the float of the bed on water. The seeds are placed on the pad and the floating bed is floated on the surface of water to allow the seeds to germinate and the germinated sprouts to grow with the roots thereof passing through the through holes.

Description

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Background of the Invention This invention re~ates to a method and an apparatus for hydroponically growing plant sprouts.
There are known a lot Oe methods Eor growing plant sprouts in soilless media. Hydroponics is one such method in which a plant is supported by a bed disposed on or above the surface of water, optionally containing nutrients, with the roots of the plant passinq through the bed and extending ~nto the water.
Several beds for hydroponics have thus far been proposed such as (a) shaped bodies, such as plates and trays, formed of a close celled, synthetic polymeric foam material, (b) shaped bodies ¦ prepared by molding a mixture of close celled, synthetic polymeric !
¦ foam particles and a ve~etable organic material, (c) plates formed¦
l of a mixture of a close celled, synthetic polymeric foam particles, ¦ open celled, synthetic polymerlc foam particles and scrabs, and (d) i perforated sheets or wire nets mounted on buoyant frames. These hydroponic beds, however, are not qoite satlsfactory in practice.
The bed of the aforementioned type (a) has a very smal;l bulk density and is~floatable by itself. However, slnce the ~ floatable shaped body ~er se has no water permeability, it lS not ~ ~ possible to sow seeds of~a plant directly thereon for germinatlon.
Thus, the shaped body is processed to form relatively large p~ér~
forations or apertures on~which seedlings are transplanted.~
lternatively, the perforations are covered with water~;absorbent !materials such as pebbles,~sand, and peat moss, in whlch seeds are sowed. ~In either case, lt is~not~easy to maintain~a suitaDle humid growing envlronment throughoat their growth. ¦
I The second, type (b) bed is suited~for the germinatlon of rice seeds. Since the vegetable organic matarial, which ~serves ¦
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¦ both as a binder for the shaped bodles and a fertilizer for the plant, is soluble in water, they are broken upon harvesting and cannot be reused.
In the hydroponic plate of type (c), the close celled foam particles serve to provide the plate with flotage, while the scrabs and the open celled foam particles serve as a water absor-bent. The scrabs additionally function as a fertilizer for the !growth of the plant. Thus, the mixing ratio of respective i components is very important in that it has a great influence upon the moisture environment necessary for the germinat.ion of seeds and the growth of the germinated sprouts. Although the avail-ability of the three components as waste materlals is one of the merits of the type (c) hed, the use of waste materia].s makes it l¦difficult to adjust the mixing ratio to a predetermined range ~because of the lack of uniformity in~quality or the waste Imaterials. Moreover, with the type (c) bed, the roots of sprouts ¦extend into the pores of the open celled foam partlc~es and the ! softened portions formed by the rot of the scrabs and entwine with , ~ ¦ each other. In harvesting, therefore, the matured sprouts are cut ¦
¦ near the roots and the roots~remaining in the bed must be allowed to rot in order to reuse thelbed. In addition, because the type (c~ bed, which contains scrabs and rot roots, is liabLe to become~
~¦ infected by germs, lt is not suited for the culture of clean plant s~routs which are generally eaten as raw. For the same 2s ! hygienical reason, the type (c) bed is not suited for indoor use,~
¦ especially of homes.
The bed of the above-described type td) is~deslgned so that when it is floated on the surface of water, the pad of~a perforated sheet or wire net is positioned just above the level of the water. Seeds oE a plant are spread on the pad for germination.i ' : I ~

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i~ o In this case, although the di~tance between -the pad and the surface of water ls maintained subs-tanti.ai.ly unchanged at an early stage of ~rowth of the sprouts, the pad will be submerged as the sprouts l grow hi.gher, i.e. with the increase in weight of the sprouts.
S Therefore, it becomes necessary to lift the bed on a suitable support to keep the sprouts in a suitable growing environment.

Summary of the Invention 1, It is, therefore~ an object of the present invention to !
provide a floating bed or hydroponically growing plant sprouts I ¦
which is free of the defects of the conventional beds. ¦ ~
¦ Another object of the present invention is to provide a ¦ I
¦floating bed of the above-mentioned type which permits easy ¦harvest without leaving any roots of the ?lant therein and can be ¦reused immediately after the harvest.
It is a further object of the present invention to provide an inexpensive, easy to produce floating bed with which the gsowth of p}ant sprouts can be effected without need of specific controls such as watering, spraying and water level l ¦
adjustment.
It is yet a further object of the present invention~to provide a method which is especrally sulted for the cultlvation~or, ¦ fresh, cle~an veqltables, such as Japanese radish sprouts and Adenophora;remotirlora Miq.
~25 ~ In accomplishing the foregolng objects,~there is provide~
in accordance with the present invention a floating bed for hydro-~
ponically growing plant sprouts, which includes a pad having a I
three dimensional structure with its opposite~sides being substan-¦
tially parallel with each~other. ~he pad is formed of a substan- 1 ~
tially hydrophobic material and is provided with one or more I I
through holes or apertures each extendin~ between and in direction substantially vertical to the opposite sides to deflne a roots .~, _L~-grow passage the~ein. Each o~ the passages has such a size as to provide capillar~ attraction. The Eloat'ng bed is adopted to float, on water with the oppoiste, top and bottom sides of the pad being positioned substantial~y ln parallel with the horizontal plane so tha-t eac~ roots grow passage can always retain water thereln duriny, the float of t'ne bed on water.
Water, on whlch the floating bed is floated, may be heated to about 40c so that the germination of the plant seeds and the growth of germinated sprouts are accelerated.
Further, said water may be provided with air flow so that the growth of the roots are accelerated.
A sun-ray lamp also may be used to accelerate the growth of the plant, regardless of day or nlght.

l In another aspect, the present invention provides a 1 method oE germinating seeds of a plant and growing the germinated I sprouts with the use of the above-described Eloatinq bed. I i :~ `
¦ Brief Descr~ptlon o~ the Drawings~ ~ I
¦ Other objects, features and advantages or the present ~ ¦
~1 20 1 invention will become aooarent rrom the detaiLed desc~rip~ion of ¦ the 2referred e.~bodiments o~ tne present inventi~on which follows, ¦ when considered in light of~the accompanylnq drawinqs, ln wnic ¦ F~g. 1 is~ a perspective vlew, cut away ln~part, schena~
tically showing one e.nbodiment of the floating bed according~to the present inventlon;
Figs. 2(a~ thro~h 2(d;) are elevational, cross-sectlonal~
¦~ ,views sche.matically showing t~e method in which the rloating bed~
thls lnvention is used ror placing~seeds of a plant, sp~outlng~, ~the seeds an~ growing the pldnt sprouts to maturity;
igs 3(a~ and 3(b) aFe perspective vi~s schem.~ically ; _ 5 -~, 1 :
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¦ ShOW1ng anOther embOàiment OL the pad according to the present in~ention; and ~ig. 4 is a pers?ective view schema-ticaLly showing an alte~ate embodiment of the pad accordlnq to the present invention.
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Description OL the Preferred Embodiments Z Fi~. 1 depicts one e~odiment o the floating bed or this invention, in which .he reference numeral L denotes a pad ormed l of a cLose celled, syntheti.c polymeric foam material such as ¦ foamed poLystyrene or foamed polyethylene and having top and bottom sides which are substantially parallel with each other.
¦ The thickness of the pad may vary according to the floatage of the foam material and the kind of the plant to be cultured.
The pad 1 is provided with one or more through holes Z
jlhaving a dlameter so that each hole may attract water therein by ¦
capillary'action. The diameter of each throuqh hole is generalLy in the range of 0.5 to 3 mm. The num~er of the through holes 2 may ¦ also vary according to the kind of the pLant and the objsct~or the ¦ ;
culture. When the floating bed is used for educational purposes, for examole, rather than the consumptlon or tne matured plant, the - 20 1 num~er of the holes can be very small. For the yrowth o~r Japanes radis'r sprouts, the pad is generally provided with about S~0 to ¦ 1000 through hoLes with a dla~e.er of~0.5 to 3 mm per 100 cm ~of~
the pad. In the specific embodlment shown, whlch~is arranged to~
grow Japanesz radish~sprQuts, the pad has a thic~ness OL 2 cm,~an ¦area OL 225 cm2 ~15 x 15 cm) and a~weight of lS g. The pad is ; ¦divided into~ four zones~e~ch having an are~ Ot 25 cm~ (5 x~5 cm)~
; ~and each provided with 144 (l~ x~12) of evenly distributed throuqh hoLes each having a diameter of 2 mm and arransed in~a honeycomb Z

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structure As d2scrLbed hereinafter, the throuah holes serve to f~lnction as the passages ol plan-t roots.
Indicated as 3 is a frame me~ber for supportinq the pad therein. T~e frame mem~er 3 is pro~lded with an ~~shaped ~¦insertlon 4 dividLng the pad into the four zones. Both o~ the frame ¦memoer 3 and the insert~on 4 suoparting the pad 1 in this emb~di-ment are also formed of the same close cell2d, synthetic polymeric material as tne pad 1 and, thus, serve as a buoyant member for the pad 1.
10When the fLoating bed having the above-described const-_ ¦ructlon is olaced on water, it floats by itsel} on the surface of .Iwater with the bottom side thereo~ positioning below the level OL
. ~ the water. The floa~inq bed of this emDodimen~ is so desLgned thatl I the bottom side thereo is submerged to the depth of 2 mm from tne ¦
15i water le~el and that a load OL 300 g 15 required for positionina~
¦ the top side thereof in parallel wit:h the watPr level. S~ince the ¦
tocal weignt of Japanes2 radish sprouts matured in the whole area of the pad generally amo~uts to 200 to 250 g, the floatLnq bed~has a sufEicient capacity for sup~ortina the sorouts thereon while ;~
201 maintainin~ the top s ce thereof above the water level.
A~method of growing s?routs from seeds to maturity with ~¦
~the~use of the floating bed according~ to the pres2nt invention is~ !
now descrlbed;below witn ref2rence to Figs ~2(a) througn;2(d).
, Seeds 5 are placed on the paa l and sufficiently applied~with~wa~er 25~ by, for example, submo~gin.c~t~e~floatina bed unaer the~level o~
water contained~in a tray 6. The wat-r~ln the;tray 6 may, if necessary, contain suitable nutrients. By the aoollcatlon o~ !
~water, the seeds are wet~ed and set adjacsne to~the mouths~of~the~
through holes 2 and, at thô same time, each o~ the~thr~ough holes~2 !
of tne pad 1 hoLds an amount of water due to ca?~llary ohe~ome~on I

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B~/ allowincJ the cloa~[lg bed to float on the water in the tray 6 (Fig. 2(a)), each OL the throuq'n hoLes 2 can continually retain a quantit~ of water therein becaus2 o~ the caDilLary attract~'on so l that there is estabilished in each througA hole a humid environment¦
suitable for the germinacion. In sowing, if the size or the se'eds ¦
is smaller than that of the-through holes 2, it is advisable to cover the pad with a ?a?er towel or a tissue pa~er, upon which ~he !
seeds are sowed.
By controllin~ ht, temperature and other growinq conditions in the customarily employed manner, the germinated sprouts, which are provided with surficient oxygen and adequate ¦ humidity, gradually grow ~ith the roots growing from the end ~- portions of the stems (or stalks) and e.Ytending through the throug~
'holes (Figs. 2(b) and 2~c). Besides the customarilly employed lS manner, there are some methods for accelerating the germination of the seeds and the growth of the plants. Water, on which the ¦floating bed is f'loated, may be heated to about 40c so that the ¦germination of the plant seeds'and the growth of germinated sproutc are accelerated. Further, sald water may be provlded with air ~ 20 ¦flow so that the growth of the roots are accelerated. A sun-ray I ~ ¦lamp also may be used to accelerate the growth~of the~plant,~ ~`
¦regardless of day or night. The roots further grow and emerge~
¦~through the bottom of the pàd to absorb nutrlen~ts. Thus, the ~
sprouts;grow further with the end portion of each of their ;stems ~ being supported within respect~ive through holes (Fig.~2(d~
~In qeneral, the germLnatlOn of s2eds and the growth of~ ~ ¦
¦ the ge~minated sDrouts are adversely affected by,~on one hand,~
drying and, on the other hand, by excess moisture. These~are~main c_uses for the retard oE germination and non-uniform growth oE~;the~l, sprouts. With the use of the floatlng bed in accordance with the ¦ -' resent invention, the hu~id environment once established in;e~ach~;
~o~ the tnrouqh holes at the =ime of sowlng can be malntalne- ¦

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¦ unchanged throughout the germinati.on or seeds and the growth o~ the~
ger~linated sprouts, provided that the tray 6 contains wa-~e~ medium in an amount sufficient to alLow the float OL the bed. That is, the sprouts can be continually ~rovided with an adequate deyree of ¦
S moisture throuqh the roots grow passaqes ~rlithOut the need or s~atering and spraying. This contributes niuch to the reduction o~
manuaL labor.
As illustrated in Figs. 2(a) through 2(d), the distance bet~,~een the top side or ttLe pad and the surface or wat0r in the ¦tray 6 gradually dec-eases with the growth of the sprouts, i.e.
with the incre~se in weight or the sprou-ts. Since the floating bed¦
_~ ¦ has a surLicient thickness and a flotage, however, t~e humidity at ~i I the top side of the pad is kept constant irrespective o the l growth stage of the sprouts. Thus j in accoraance with the method l of this invention, plant sprouts can be grown to mature in a stable manner because the caPillary attraction in the roots grow passaqes~
defined by the th~ough holes and the flota5e of the bed constantly~
- produce a mode~ate humid envLronment~ Therefore the present I ¦
~ I invention ma~es it possible to grow Adeno?hora remotiflora Miq.
-~ ~ 20 ~with an improved germination rate.
~:3 ~ ~ The Lnatu ed s?routs ~ay be exposed to liqht for qreeni~nq ¦before harvesting. Since the roots or one sprout do not ent~ine ¦with other sprouts in the pad, t;e roots of each sprout can be ¦ ~ ¦easily pulled off from the pad without leavinq the root tlps in 25` the through holes. ~Thus, upon harvest, the floating bed is ready 1~;~
~for reuse. In home culture, tne pad may be divided into a~
l plurality of regions with respective regions being sowed in ; dlfferent days. This makes lt possible to daily harvest and~
¦ consume fresh sprouts with one floating bed. The erovision~of~the , ~ 30 1 pre~iously described ~-shaped inser~ion is conveni~ntly empLoyed I I ~to achieve this purpose.
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,.. I _ g , v The floatincJ bed o~ the pres2n~ invention may be modlfiedl in a variety of constructrons. Fi~s. 3 (a) and 3(b) show an ¦ !
! aLternate emDodlmerlt o~ the pres2nt inverltion, in wnich the pad 11 ¦ l ¦is formed of a plurality of plate elements 17. Each elemerlt 17 ¦
¦has a recess~d portion 18 so that, when they are integrally bonded ¦
¦face to face, slits 12 are defin~d therebetween. The slits serve as roots grow passa~es like~ise the through holes 2 of ~ig. 1. Ii The wldth of each slit 12 may cenerally be in the ragne of 0.5 to 3mm.
In the e~ocdiment shown in Fi~. 4, the pad 21 is formed from a plurality of rods 27 each generally circular in cross i_J ¦section. The roas 27 are intesrally bound to~ether so that a ¦plurality of voids 22 extending along the length of the rods 27 ¦are derined between them. The voids 22 serve as the rocts grow lS ¦passage or the oad 21. In this case, at least one ol the rods 21 ¦can be~formed into a cylinder so that the center hole or the ¦¦cylinder can serve as at least Qart of the roots grow passa~es ¦ !
l The pads sho~n in Fiqs. 1, 3 and 4 can oe used by ; ! themselves without the support by a frame memoer. When the pad LS
used in co~ination with the~frame me.nber, the latter is generally ¦
for~ed of a c10s2 celled, synthetic polymeric roam material so thatl, the frame can ~unction as~buoyant met~oer of the bed. In this case,'~
the pad may be formed or a~materlal other than the~close celled, ¦
I ¦synthetic polymeric foam material.
25 ~ ~ ~ The ~floating bed according to the present invention:has~
a very sLmQle s~ructure and lS very effecti~e in hydroponlcally ¦ growlnq a variety of plants. 8y varying the size and thlc~ness o ¦
` , the pad, the floating bed can be used in varloùs manners such~as~on¦
¦ ~ a larqe scale industrial ?roduction of plant sprout~s, for home~
1 30 ¦ culture and for educational purposes. The floating bed may be ~ : .
¦used in trays, ponds, rivers, lakes, bags, etc. I
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The invention may be em~odied in other speciEic forms witnout departing ~rom the spirit or essential characteristics t'nereof. The present embodiments are therefore to be considered in all respects as illustratLt/e and not rastrictive, the scope of the invention being indicated by the appended claims rather than by t'ne foreqoing description, and all changes which come within the me.aning and range of equivalency of t'ne claims are therefore intended to be embraced therein.

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Claims (18)

Claims

1. A floating bed for hydroponically growing plant sprouts, comprising a pad which has a three dimensional structure with its opposite sides being substantially parallel with each other and which is formed of a substantially hydrophobic material and is provided with one or more through holes each extending between and in direction substantially vertical to said opposite sides to define a roots grow passage therein, each passage having such a size as to provide capillary attraction, and said floating bed being floatable by itself on water with said opposite sides of said pad being positioned substantially in parallel with the horizontal plane, whereby each passage can continually retain water therein during the float of said bed on water.

2. A floating bed as set forth in claim 1, wherein said one or more through holes are in the form of slits.

3. A floating bed as set forth in claim 1, wherein said pad is formed of a close celled, synthetic polymeric foam material.

4. A floating bed as set forth in claim 1, further comprising an outer frame member provided around the circumference or said pad for supporting said pad thereon.

5. A floating bed as set forth in claim 4, wherein said pad is formed of a close celled, synthetic polymeric foam material.

6. A floating bed as set forth in claim 4, wherein said outer frame member is formed of a close celled, synthetic polymeric foam material.

7. A floating bed as set forth in claim 6, wherein said pad includes two or more plates integrally bonded face to race with each other, each plate having a recessed portion or portions so as to define said roots grow passage or passages between said plate.

8. A floating bed as set forth in claim 7, wherein each of said recessed portions has a shape so that slits are defined between the neighboring plates.

9. A floating bed as set forth in claim 6, wherein said pad includes three or more rods each of which is circular in cross section and which are integrally bound with each other to define one or more spaces between said rods extending along the length of said rods, said space or spaces serving as said roots grow passage.

10. A floating bed as set forth in claim 9, wherein at least one of said rods is in the form of a cylinder, so that the hole of said cylindrical rod serves as a part of said roots grow massages.

11. A floating bed as set forth in claim a, further comprising an X-shaped insertion with respective ends being connected to said outer frame member for partitioning said pad into four regions of generally the same area.

12. A method of germinating plant seeds and hydroponically growing the germinated sprouts, comprising the steps of:
floating a floatable bed by itself on water optionally containing nutrient, said floatable bed including a pad which has a three dimensional structure with its opposite sides being substantially parallel with each other and which is formed of a substantially hydrophobic material and is provided with a plurality of through holes each extending between and in direction substan-tially vertical to said opposite sides to define a roots grow passage therein, each passage having such a size as to provide capillary attraction, and said floatable bed being floatable by itself on water with said opposite sides of said pad being positioned substantially in parallel with the horizontal plane, whereby each passage can continually retain water therein throughout the float of said bed on water, sowing the seeds on said pad, and allowing the seed to germinate and the germinated sprouts to grow with the roots of each sprout passing through respective one of said passage and extending into the water.

13. A method as set forth in claim 12, wherein said sowing includes placing the seed on said pad directly and adjacent to the mouths of said passages.

14. A method as set forth in claim 12, wherein said sowing includes covering the surface of said pad with an absorbent material, and placing the seeds on said absorbent material.

15. A method as set forth in claim 12, wherein said absorbent material is a paper sheet or an open celled polyurethane foam sheet.

16. A method as set forth in claim 12, wherein said water is heated to about 40°c so that the germination of said plant seeds and the growth of germinated sprouts are promoted.

17. A method as set forth in claim 12, wherein said water is provided with air flow ceaselessly.

18. A method as set forth in claim 12, wherein a sun-ray lamp is provided for continuing the growth of said plant also at night.