Note: Descriptions are shown in the official language in which they were submitted.
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~$T~OD AND APPARATUS FOR ~SB I~
PLANT GRO~T~ PROMOTIO~ A~D FLOWER D~V~LOPNB~T
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Field of the Invention
The curren~ invention relate~ to green plant growth promoting
apparatu~ for use in maximizing the production of food crop ~nd
flowering plants. It involves the provi~ion of ~everal ~pecially
con~tituted thermopla~tic screen~ which offer ~ingley or in combi-
nation ~hade from the auxin-destroying W radiation, the growth
retarding photoJynthesi -unu~able green and infra-red light o~ tha
sun, but the same time, will optimize the photo~ynthesi~ rate of the~
plant and encourage rapid growth. In addition, by c~reful ~election
of the ~creen wavalength combination~, growth control and flowering
may be managed~by those ~killed in the art of horticultureO
Background of the Invention
Numerou attempts have been made to control the growth anviron
ment of crop plants ~o as to improve yield and control tha timing o~
.
flowering. The~e include providing shelter from wind and heavy
rain, as for example by errection of a "greenhou~e"r or by ~applying
various chemicals which control growth by simulating the effects of
the natural plant hormones. Inevitably there i~ a trade off, in
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~ the ca~e of the greenhou~e, ~corching become~ a problem due to light
focu~ing and the overheating created by the "greenhouse effect" of
trapping radiant energy, wherea~ in the case of ah~mLcal application
there are attendent problems as~ociated with re~idue~ both in the
food crop and in the ~oil.
In order to under~tand fully the ~ignificance of the current
invention it is fir~t necessary to review the constitution of
terre~trial sunlight and to reali~e how plant~ exploit this radia-
tion.
Terre~trial ~unlight ha~ been con~idered to consi~t of short-
wave ultraviolet light (W -B, 290-320 nm), long-wave ultra-violet
light ~W -A, 320-400 nm), vi~ible light (400-700nm) and infra-red
light (700-2500 nm). On a clear day at ~ea level, the di~tribution
of solar radiation i3 about 1 - 2 ~ W, 42% yi~ible and 57% infra-
-red. It i~ now generally recognized that the W -B radiation i~
dangeroue to all living cell~ leading to variou~ genotoxlc di~order~
by mutation and will cau~e, at high enough expo~ure level~, plant
and animal cell death. W -A on the other hand i~ apparently harm-
lea~ to animal ti~uee at natural radiation level~, but green plants
have utilized the hormone-destroying effect of W -A light to control
or regulate their growth, while protecting themselve~ a~ be~t they
can from the dangerous UV-B rays with the pigment chlorophyll. It
ha~ been known ~ince Darwin'~ time that plants produce a grow~h
atimulating sub~tance (hormone or auxin) near their growth tips
which diffu~e~ downward~ promoting further growth and that if
completely ~haded, plant~ will grow, for a limited period, at about
thrse time~ their illuminated rate (e.g. "forcing" of hyacynthe ox
rhubarb ~hoot ~ and that the bending of plants towards light i~
cau~ed by the protection of the auxin from light denaturation on
the dark~ide of plants grown on say a window ~ill. The ~pecLfic
wave-lengths of light which denature auxins lie in the W-range, 290
- 340 nm and the photoly~is of such auxins can occur even at quite
meager l~ght intensitie~. Prevention of photolyeis would render
the plants continuou~ly ~en~itive to their own growth ~timulation.
In a similar manner, the induction of flower formation and develop-
ment ha~ been determined to ~e influenced by the presence and the
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- intensity of natural red light and conaequently flowering may be
encouraged or delayed by manipulating the filtered environment ao as
to provide or absorb thoae wavelength6 re~pon~ible. It i~ the
purpo~e of thi3 invention to provide auch an environment or environ-
ment3.
Summary of the Invention
Briefly described, the pre~ent invention provide~ method and
apparatua for encouraging maximal plant growth which method and
apparatu~ comprise a light filter which preventa the natural decay
of plant growth ~timulating material~ by ab~orption of W radiation
while permitting photo0ynthesi~ to occur with blue light in the
abaence of attendant heat generating and dehydrating radiations
cauaed by green, yellow and infra-red light. Ths objective is made
posaible according to the preferred embodiment of the invention by
interpoaing a combination of filters made of ~olid material between
the sun and the growing plant~ which block out radiation in thoae
wavelength~ which are either physiologically harmful or which retard
growth, but do not inhibit tho~e wavelengths which are nece~sary for
photosynthesis, metaboli~m, differentiation and developmsnt.
The apparatus of the preferred embodiment of the present inven-
tion comprise~ at leaat three filter~ employed either together,
~eparately, continuoualy, or diacontinuoualy, a~ a canopy ahove
growing plant~.
It i~ recorded in the prior art that plants may be protected
from aolar radiation by the provi~ion of a ~ingle filter which will
~imultaneou~ly and selectively abaorb UV and other radiations to
protect plant~ from phy~iologlcally dangerous radiation (e.g~
wa~elengths of 300 - 330 nm, in Mutzha~, U.S. Patent 4,200,360);
however, the present invention allows the nur~aryman to vary the
wavelength range and intenaity continuoualy, and during the growth
of hi~ crop. The advantage here i~ that variou~ ~tage~ of plant
development ~uch a~ flowering or fruiting may be modified and
managed as well a~ the rate of the planta growth.
1 309~6.j
- Other objects, features and advantages of the present inven-
tion will become apparent upon reading and understanding this
spec;f;cation in conjunction w;th the drawings.
Brief Description of the Drawings
Fig. 1 is a graph representat;ng the selective absorption of
wavelengths of sunlight, in accordance with a preferred embodiment of
the present invention.
Fig. 2 is a cross-sectional, side view of an apparatus in
accordance with the present invention, depicting a preferred embod-
iment thereof.
Detailed Description of the Pre-ferred Embodiment
Attention is now d;rected to more specif;c details' of pre-
ferred embodiments of the method and apparatus of the present
invent;on, with reference in greater detail to the drawings. In
accordance with the present invention, a filter assembly 10 displays
selective and variable radiation absorption features. In the
preferred embodiment, the filter assembly 10 comprises three screens
12, 14, 16 (or three sets of screens 12, 14, 16).
The outer screen 12 of the three screens provides a mechanism
by which the plants may be protected from harmful UV radiation. The
outer screen 12 ls constituted so as to exclude from the grow~ng
pl'ants, by absorption, that port.ion of UV-light known to cause DNA-
~amage and denaturation of the naturally occuring plant growth
promoters and auxins, but at the same t~me to transmit as ~uch whit
light and i'nfra-red as practical. The wavelengths to be absorbed ~y
this outer filter screen 12 lie, therefore, in the range 290 - 340 nm.
~See Fig. 1.)
A suitable material for the outer screen 12 is any thermo-
plastic material or acrylic resin in the form of either a thin film or
- woven or laminated material but exhibiting the property of being
transparent to solar energy wavelengths above 340 nm which are those
associated with heat and photosynthesis. Suitable materials for the
outer screen 12 when in film form are resins~of polyv;nyl chloride,
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polyolefins such as polyethylene and polypropylene, or acrylic resins
such as polymethylmethacrylate. Copolymers such as polyeth-
ylene/vinyl acetate and butadiene/styrene would also su~fice. Such
resins may also include plasticisers such as phthallate esters. The
outer screen 12 includes UV absorbers of various chemical types at
such concentration to prov;de both longevity to the material and
selective absorption of UV below 340 nm. It is preferrable that the
outer screen 12 shall not have significant absorption, i.e. greater
than 20~, of the natural wavelengths of light above 340 nm. In
preferred embodiments of the present invention, the UV absorbers
constitute between 0.01 and 0.5% by weight of the screen material. An
example of a suitable UV absorber is (2-Chloroethyl) phosphate or
acetophenone at a concentration of 0.1 w/w. Another example of d
suitable absorber is 2[2 hydroxy - 5 menthylphenyl] ben~otriazole at
a concentration of 0.05% w/w.
A preferred material for the outer screen is polyethylene Filn
of thickness between 100 and 300 microns, for example 200 microns, and
this may be a single film or a laminate form with a reinforcin~ nylon
or polyester net to give greater physical strength. The resin should
also he light stable and non-volatile at the reiatively h~yh
temperatures used in blow forming, extrusion or callendering of lay-
flat film. (i.e. about 150 C). It is also essentlal according to the
invention that the outer film be not polished, and, preferrably, it
should be finished as a matte or taffeta surface to provide a llght
diffusion~effect. The growth of plants is enhanced by diffused rather
than direct light.
The second screen 14, which is, preferrably, arranged be~ween
the outer screen 12 and tt!e grow~ng plants, provides, in the preferred
embodiment, protection from the unnecessary heating effect of light
within the spectral wave1ength ranges 510 - 61Q nm and 8Q0 - 2500 nm.
(See Fig. 1.). In the preferred embodimen~, the second screen 14 is
comprised of a~set of two screening fllms. These two films making up
the second set-of screens are ideally identical to each other although
not necessarily so. The ~obJective of this set is to provide the
plants~ at the dlscretion of the nurseryman, with an optional single
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- or double degree of shade from heat (800 - 2500 nm~ and intense green
- and yellow light tS10 - 610 nm) but permitting maximum photo-
synthesis, synthesis of chlorophyll and photomorphogenesis,-to occur.
These screens should absorb maximally within the wavelength range 510
- 610nm and conseque~tly appear purple or violet Tn colour. Suitable
materials for these screens are as described for the outer screen lZ
but there is no necessity to include UV absorbers and a suitable
thickness is between 100 - 300 microns. However, included in these
screens according to the present invention and to achieve the
objective of absorbing light in the range 510 - 610 nm, a pigment SUC~l
as CI pigment Violet 37 (carbazole dioxazine) must be included in the
formulation of the said screens at a concentration of, for example,
0.05% w/w. This same pigment accomplishes the desired absorption of
infra-red radiation of wavelengths between 800 nm and 2500 nm.
Preferrably, the pigment or dye used is heat and light stable. Care
must be taken however when selecting d suitable pigment that little,
if any, absorption occurs in the photosynthesis-essential ranges of
340 ~ 510 nm ~blue) and ~10 - 710 nm (red~. A combinatlon of -the
previously described, UV absorbing, outer screen 12 and this second
screen 14 (or set of screens 14~ absorbing green, yellow and infra-red
light, provide the plants with selected solar protection. Experience
has shown growth rates to be enhanced by up to three times the
unprotected rate. This combination of screens has been sho~lln to
encourage growth and development, especially of young plants.
In order to delay the flowering and ~ruiting of mature plants~
it -s necessary to provide, according to the invention, a third screen
16, comprising a set of at least one additional or alternative filter
which will absorb those wavelengths of light known to be e~fective in
lnducing flowering, i.e. red liyht in the range 610 - 710 nm.
Provision of this third screen filter 16, either in combination with
the outer screen 12 and the second set oF screens 14 previously
described, or in combination wlth just the outer screen 12, will
permit synchronisation of plant growth and flowering. When flowering
is required, the nurseryman has simply to remove this third screen
filter 16 which absorbs light in the range 510 - 710 nm and replace it
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- by the second screen 14 which transmits red light in the range 610 -
710 nm. This third screen 16, in the preferred ~mbodiment, also
absorbs infra-red radiation ~00 - 2500 nm). The objective of the
third screen filter 16 is achieved by constructing a filter material
as that previously described for the second set 14 but including in
the formulation a pigment which will absorb substantially only red,
green and yellow light in the range 510 - 710 nm, bu-t which will
transmit light in the blue region of the spec~rum, i.e. between 340
and 500 nm. (See Fig. 1.) Such a filter will appear blue and a
suitable pigment would be, for example, CI pigment blue 60 (Cromo-
ptha, Blue A3R, Indanthone blue~. This same pigment accomplishes
desired absorption of infra-red radiation of wavelengths in the range
8no nm and 2500 nm. Preferrably, the pigment or dye utilized is heat
and light stable.
It is seen that the filter assembly 10 of the present invention
functions as a growth regulator and promoter and that each of the
three screens 12, 14, 16 individually contributes to the ideal
photosynthetic and development needs of green plants. Because any
one green plant does not use the same wavelengths of solar radiation
at different times during its growth and development, the present
invention provides a means whereby the nurseryman can choose which
filtered light environment he thinks fit for his crop. This choice of
environment is accomplished, in accoraance with the preferre~ enl~
bodirnent, by selectively interposing one or more of the filter
screens I2, 14, 16 between the growing plants and sun.
Furthermore, in addition to its functions as a growtll reg-
ulator and promoter, the present invention provides environmental
control by eliminating those wave-lengths of light which cause
overheating, dehydration and wilting. These energy-rich wave-lengths
of light do their damage without contributing to the photosynthetic
capacity of the plant, and, therefore, are of little benefit to the
plant during the gro~th period in the natural environment. Elimi-
nation of these rays permit unhindered growth during dayl~ght hours.
In order to capitalize on such growth stimulation, the plants su
~ 35 stimulated need~to operate their photosynthesis machinery to maximum
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- advantage. Maximal photosynthesis is governed by several l;mit;ng
factors including temperature (range 68 - 86 F), carbon dioxide
concentra-tion (natural limit 0.03%, but ideally 10 - 15%), water
content (plants must remain turgid~ and light intensity (ideally
about 33X full sunlight intensity~. With respect to the current
invention, in addition to protecting the plant from mutation and
auxin photalysis, the apparatus is capable of controlling photo-
synthetic rate by preventing overheating and, therefore, excess water
loss, and providing the plant with only those wavelengths of light
usable in photosynthesis, i.e. red and blue light, thus preventing
the 3rowth and photosynthesis retardation effect o~ hi~h light
intensity known as solarization. The apparatus brings maximum
advantage to crops grown in hot, arid, high light intensity regions,
e.g. Mediterranean and tropical climates, but considerable advantage
should be accrued in temperate zones.
Whereas, 100% absorption of radiation within the stated
wavelengths is an ideal embodiment of the present invention, the
invention is practiced whenever there is absorption of radiation, in
any amounts, of any wavelengths within the stated ranges of wave-
lengths. Preferred embodiments of the present invention absorb
biclogically signif;cant amounts of radiation of substantially all
wavelengths within the stated ranges of wavelengths. One example of
a filter assembly 10, in accordance with the present invention,
i~cludes an outer screen 12 contain;ng an agent or agents which
a~sorbs at least ~0~ of the UV radiation within the stated ran~es of
wavelengths, 290 - 340 nm; and the second and third sets of screens
14, 16 contain agents which absorbs at least 50% of the respective
green/yellow, red and infra-red radiation within the stated ranges of
wavelengths (510 - 6~0 nm and ~00 - 2500 nm) and (610 - 710 nm and 80¢
- 2500 nm), respectively.
A filter assembly 10 in the form of a greenhouse 20 o~
conventional construction exemplifies a form in which the growth
promotors may be supported and varied (See Figure 2). In such a
greenllouse structure 20, the outer screen 12 o~ the filter assembly 10
fnrms the semi-permanent weather structure ~i.e. roof and sides) of
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the greenhouse. The second screen 14 and third screen 16 are mounted
on rollers 22, 23 inside the greenhouse, between the outer screen 12
and the growing plants 30. Hoisting ropes 25, 26 are connected to the
ends of the second screen 14 and third screen 16 and extended over
pulleys 27, 28 at the peak 29 of the greenhouse 20. Thus, the second
screen 14 and third screen 16 func-tion as blinds or curtains which the
nurser~nan selectively interposes, alternately or together, between
the outer screen 12 and the plants 30 by unrolling and rolling th
screens 14, 16 using the ropes 25, 26 and rollers 22, 23. ~lowever, the
scope of the present invention is not to be limited to the physical
structure of a canopy or greenhouse.
In an alternate embodiment of the present invention, the
filter assembly 10 comprises only two screens or sets of screens which
are employed either together, separately, continuously or discon-
tinuously between the radiation source and th~ plants. In such an
embodiment, one' screen (i.e. the stationary screen~ possesses the
absorption qualities of both outer screen 12 and second screen 14 as
descrlbed above, and the other screen 16 (i.e. the retractable
screen) absorbs, at least, radiation of wavelen~ths 610 - 710 nm.
Whereas, the present invention has been described in detail
with- particular reference to preferred embod~ments thereof, it is
understood that modifications and var;ations may be effected within
the spirit and scope of the invention, as described before and as
defined in the appended claims.
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