Plant husbandry – Water culture – apparatus or method – Individual support
Reexamination Certificate
1999-02-01
2001-09-11
Jordan, Charles T. (Department: 3644)
Plant husbandry
Water culture, apparatus or method
Individual support
C526S201000
Reexamination Certificate
active
06286254
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water-retaining support (or carrier) for plant which can support or hold a plant at the time of the growth of the plant and can also function as a source for supplying water to the plant. More specifically, the present invention relates to a water-retaining support for plant which can supply water to a plant without inhibiting the growth of the plant, when the support is used as a water-retaining support for fluid seeding (or seeding using a fluid), farm cultivation, field (or bare ground) cultivation, virescence (or greening) engineering, etc.
The water-retaining support for plant according to the present invention is also usable in combination with another plant support such as soil so as to enhance the water-retaining ability of the other plant support (i.e., usable as a water-retaining agent) at the time the growth of a plant.
BACKGROUND ART
Polycarboxylic acid-type highly water-absorbing resins, especially polyacrylic acid-type polymers, which have been used in a large quantity for diapers, menstrual goods, etc., are also brought into use in the field of agriculture due to their inexpensiveness and excellent water-retaining ability.
For example, hydrogels of the polyacrylic acid-type polymers have been used as a support for fluid seeding; or a water-retaining support for virescence engineering, water-saving cultivation, or cultivation on sandy soil, by utilizing their water-retaining ability.
However, it has been recognized that the conventional polyacrylic acid-type hydrogels affect the growth of a plant, and particularly, they cause a marked inhibition of the root origination and root elongation when the hydrogels are used in an amount exceeding their appropriate amount (Kazuo Kawashima, et al., “Influences of Highly Water-Absorbing Polymer Materials on Initial Growth of Crops,” Sand Dune Research, 31(1), 1-8, 1984).
Particularly, when the conventional polyacrylic acid-type hydrogel is used as a support for tissue culture, a support for fluid seeding, and a support for virescence engineering, a plantlet, seed, etc., of a plant are caused to directly contact the high-concentration polyacrylic acid-type hydrogel, and therefore its root origination and root elongation are markedly inhibited, whereby the use of the polyacrylic acid-type hydrogel is severely restricted. It has also been recognized that, in a case where the conventional polyacrylic acid-type hydrogel is used as a water-retaining support for farm or field cultivation, the elongation of the root is inhibited when the concentration of the polymer in the vicinity of the root is increased so as to enhance the effect of the water-retaining support.
As an example of the phenomenon such that the above-mentioned hydrogel comprising a polyacrylic acid-type resin markedly inhibits the growth of a plant, there has been reported an experiment wherein distilled water was absorbed into a crosslinked sodium polyacrylate so as to form a hydrogel, and the thus obtained hydrogel was caused to contact seeds of cucumbers and kidney beans for respective periods of time (3, 6, 9, 12, 24 and 48 hours), and then the states of the germination and root origination of the seeds were observed (Kazuo Kawashima, et al., “Influences of Highly Water-Absorbing Polymer Materials on Initial Growth of Crops,” Sand Dune Research, 31(1), 1-8, 1984).
As a result of such experiments, it has been reported that the growth of roots was markedly suppressed in the case of cucumber seeds, when they are caused to contact the hydrogel for 36 to 48 hours, and that the inhibition of root growth was also observed similarly in the case of kidney beans. Further, it has been reported that the &agr;-naphtylamine-oxidizing ability of the root was markedly reduced when the root is caused to contact the hydrogel for 5 hours or more. In this report, such growth inhibition and functional hindrance are presumably attributable to a fact that the plant cannot effectively use the water contained in the hydrogel.
On the other hand, it has been reported that, when rice seeds were sown on a hydrogel which had been prepared by causing crosslinked sodium polyacrylate to absorb water, and then the process of the root origination was observed, serious hindrance in the root origination was recognized (Yorio Sugimura, et al., “Utilization of Highly Water-Absorbing Polymer as Virescence Engineering Material,” Techniques of Virescence Engineering, 9(2), 11-15, 1983). In this report, no hindrance in the root origination was observed when the hydrogel was dialyzed with tap water, but the recovery of the root growth was not observed even when the hydrogel was dialyzed with distilled water. In this report, it is presumed that, when the hydrogel is washed or dialyzed with a weak electrolytic solution such as tap water, the water-absorption amount force toward the hydrogel was weakened, and the migration of water from the gel to the root hair is facilitated, thereby to solve the hindrance in the root origination.
It has also been reported an example wherein the elongation of soybean root was markedly inhibited in a soil which had been mixed with a crosslinked sodium polyacrylate hydrogel, as compared with that in the case of a polyvinyl alcohol-type hydrogel (Tomoko Nakanishi, Bioscience & Industry, 52(8), 623-624, 1994). In this reference, this phenomenon is presumably attributable to a fact that the water in the sodium polyacrylate hydrogel is less liable to be utilized for a plant.
As described above, it has heretofore been considered that the inhibition of the growth of a plant in a hydrogel comprising an alkali metal salt of crosslinked polyacrylic acid is attributable to a fact that the water in the hydrogel is not effectively utilized for the plant.
An object of the present invention is to provide a water-retaining support for plant which has solved the above-mentioned problems of the hydrogel water-retaining support encountered in the prior art.
Another object of the present invention is to provide a water-retaining support for plant which has a water-retaining ability comparable to that of the conventional polyacrylic acid-type hydrogel, and does not substantially cause an inhibition in root origination or in root elongation.
Disclosure of Invention
As a result of earnest study, the present inventors have found that the effect of a hydrogel is too strong to recognize that the inhibition of the root elongation is simply attributable to the effectiveness in the utilization of water in the hydrogel.
As a result of further study based on the above discovery, the present inventors have also found that the calcium ion-adsorbing ability in the hydrogel has an important effect on the inhibition of root origination or the inhibition of root elongation of a plant which is in contact with the hydrogel.
The water-retaining support for plant according to the present invention is based on the above discoveries and comprises a hydrogel-forming polymer having a calcium ion absorption of less than 50 mg per 1 g of the dry weight thereof and having a water absorption magnification in ion-exchange water (at room temperature; 25° C.) of 100 or more.
Herein, the “water-retaining support” refers to one in a “dry state” unless otherwise noted specifically. As a matter of course, when such a support is distributed or circulated in an actual market, etc., the support may also be in a “hydrogel” state wherein a part or the entirety of the support retains water therein (the same as in the description appearing hereinafter).
As a result of further study based on the above discovery, the present inventors have found that there is a case wherein the above-mentioned “calcium ion absorption (amount)” may greatly be affected by the content of carboxyl groups bonded to the polymer chain of the hydrogel-forming polymer.
The water-retaining support for plant according to the present invention is based on the above discovery and is one comprising a hydrogel-forming polymer having a carboxyl group bonded to the polymer chain thereof, and having a content of alkali me
Mori Yuichi
Obonai Yasuhiro
Yoshioka Hiroshi
Jordan Charles T.
Leydig , Voit & Mayer, Ltd.
Mebiol Inc.
Palo Francis T.
LandOfFree
Water-holding carrier for plants does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water-holding carrier for plants, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water-holding carrier for plants will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2447513