GB2181332A

GB2181332A - Plant growth regulating device

Info

Publication number: GB2181332A
Application number: GB08623038A
Authority: GB
Inventors: John Dalziel
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1985-10-14
Filing date: 1986-09-25
Publication date: 1987-04-23
Also published as: ZA867479B; DE8627442U1; DE3634997A1; GB8623038D0; GB2181332B; GB8525271D0; FR2588444A1; IT8621941A0; AU6343086A

Abstract

A plant growth regulating device adapted for use with containerized plants consists of an elongated water-absorbent fibrous wick impregnated with a plant growth regulating composition such as paclobutrazol.

Description

SPECIFICATION Plant growth regulating device This invention relates to a plantgrowth regulating device and in particular to a plantgrowth regulating device for regulating the growth of pot plants. By this term "pot plant" is meant a plant grown in a pot or any other container, for example, a hanging basket or window box.

The treatment of pot plants with plant growth regulators may be desirable, for example to give a more compact growth habit. In low light conditions, such as are frequently encountered by domestic indoor pot plants, plant growth regulators may reduce etiolation. However, plant growth regulators are generally formulated for use on the large scale by commercial growers and are difficult or inconvenient for the domestic userto apply at the correct dosage to a limited number of pot plants.

According to the present invention there is provided a plant growth regulating device adapted for use with containerized plants which comprises an elongated water-absorbent fibrous wick impregnated with a plant growth regulating composition.

In use, water applied to the pot plant is conducted through the water-absorbent wick, whereupon at least a proportion ofthe plant growth regulator composition absorbed in the wick dissolves in the water and is distributed to the vicinity of the roots.

Thus the fibrous wick may be inserted into the top of the growing medium of the pot plant, where it acts for example when the pot plant is top watered. The growing medium may be soil for example, peat or potting compost. Alternatively, the pot plant may be positioned above a reservoir of water and the fibrous wick inserted into the base of the potthrough the drainage holes and left projecting slightly to dip into the reservoir. tn this way all that is necessary is to top up the reservoir at intervals to achieve a uniform and regular supply of water and dissolved plant growth regulator composition to the roots. The fibrous wick may be left in the pot until its charge of plant growth regulating composition is exhausted or it may alternatively be removed when the desired level of plant growth regulating effect is observed in the plants.

The plant growth regulator composition may have a solubility in water such that rate of supply of plant growth regulator to the plant by means of dissolution in water passing through thefibrous wick corres ponds to a desired application rate. Alternatively, for more soluble plant growth regulators,thefibrous wick maybe loaded with essentially a single charge of active compound. We have found that compositions based on the plant growth regulating compound paclobutrazol (1 - (4-chlorphenyl) -4,4-dimethyl - 2- (1 H - 1,2,4 -triazol - 1 - yl) -penta - 3 - ol) areespecially suitable as plant growth regulators.

The plant growth regulating composition may also be a growth rate enhancer, such asthe gsbberetlic acids.

Other plant growth regulator compositions which may be used in the device ofthe present invention include E 1 4- chlorophenyl) - 4,4 - dimethyl - 2 -(1,2,4-triazol- 1 -yl)-pent- 1 -ene-3-ol; (El-I - cyclohexyl - 4,4 - dimethyl - 2 - (1 H- 1,2,4 -triazol -1 - yl)4 - hydroxyl - 5,5 - di methyl hexa ne.

Itwill be appreciated that the dimensionsof the fibrouswickwill be adapted to the purpose forwhich they are intended. Thus the wick will be sufficiently long to reach the vicinity ofthe roots ofthe plant when inserted into the pot but not so long that an excessive length ofwick is left sticking out of the pot.

Similarly, the diameter of the wickwill be sufficient to provide a suitablesupplyofwatertothe plant. A number of separate wicks maybe employed for large pots. Typical dimensions of domestic use will be a length offrom 3to 20cm (forexamplefrom 3to 15 cm) and a diameteroffrom 1 to 10 mm,for example from 2 to 7 mm.

The wick may conveniently be cylindrical in shape, although other shapes may be used if desired.

The wick is preferably sufficiently rigid to be inserted into the soil of the pot plant. The fibrous wick may be inherently rigid or may be encased in a rigid outer lining, for example atube of plastics material which may be perforated to allowfree movement of the chemical. An outer lining may also serve asan applicator to protectthe userfrorn contact with the plant growth regulating composition when inserting the wick and may be removed subsequently.

The amount of active ingredient in the plant growth regulating composition applied to the fibrouswick may be between 0.05 mg and 5 mg depending on the size ofthe container and type of plant. Preferably the fibrouswickwill contain between 0.1 mg and 0.5 mg.

Typica Ilythe fibrous wick will contain0.2mgofthe active ingredient. The total charge of active ing redient in the plant growth regulating composition delivered to the growing medium in the container may be as low as 0.05 mg or as high as 10 mg and typically will be between these two extremes. The total charge may be achieved by inserting one or morefibrous wicks into the growing medium.

To assistthe transport of wateralong the length of thefibrous wick, the fibres are preferably aligned substantially along the longitudiinal axis ofthe wick.

To increase the porosity ofthe wick, the fibres may if desired be crimped. Suitable fibrous materials for use in the fibrous wick include cellulose diacetate fibre, and especially crimped cellulose diacetate fibre. The fibrous wick may be made bycompressingthe alignedfibres in the desired shape, optionally with heating. If desireda binder may be applied to add rigidity to the fibrous wick. However the invention is not limited to these fibres and alternative types of fibre which are suitable for compositiontoform a wick of the invention will occur to the man skilled in the art.

The plant growth regulating composition is conve niently applied to the fibrous wick by wetting the wick with a solution of the plant growth regulating composition in a suitable organic solvent and then allowing the organic solvent to evaporate. A wide range of solvents may be used depending on the nature ofthe plant growth regulating composition and the material ofthe fibrous wick. Thus for example when using paclobutrazol as the plant growth reg ulating composition and a fibrous wick based own cellulose diacetate, we have foundthat isopropyl alcohol isa especially suitable solvent.

The invention is illustrated bythefollowing Examples.

EXAMPLE 1 Rigidfibrous wicks consisting of longitudinally aligned crimped cellulose diacetate fibre in the form of4 mm by 45 mm cylinders were impregnated with a solution of paclobutrazol in isopropyl alcohol and the solvent was allowed to evaporate off. The solution of paclobutrazol was applied to the top ofthe cylindrical wick from a micropipette/syringe. A 100 microlitre charge of a solution containing 50 g/l paclobutrazol in isopropyl alcohol was used to give a fibrous wick loaded with 5 mg active ingredient, and a 100 microlitrecharge of 5g/l and O.5 g/l solution respectively used to give fibrous wicks loaded with 0.5 mg active ingredient and 0.05 mg active ingredient respectively.

-The cylindrical fibrous wicks were inserted into the tops of 3 inch pots containing marigold and tomato seedlings which had reached a heightof4cm in John Innes No 1 Potting Compost. Plant heights were measured after 7 and 14 days andcomparedwith untreated controls. The results are presented in Table I (marigolds) and Table II (Tomatoes).

TABLE I Retardation on Marigolds Concentration of % Retardation paclobutrazol on wick ~~~~~~~~~~~~~~~ (mg per wick) 7 DAT* 14 DAT 0.05 5 4 0.5 15 22 5 29 43 *Days after treatment.

TABLE 11 Retardation on Tomatoes Concentration of % Retardation paclobutrazol on plug (mg perwick) 7 DAT 14 DAT 0.05 37 3S 0.5 51 49 5 66 64 The marigolds were assessed for any signs of adverse effect on flowering and no difference could be detected between the average number of buds and fiowers as compared with the untreated blank.

EXAMPLE 2 The effect ofthe length of time the fibrous wick remains in the soil was assessed using impregnated wicks preparedas in Example 1. Tomatoes grown in 4 inch pots with John Innes Potting Compost No 1 were treated with impregnated fibrous wicks which were removed 1,7 and 14 days respectively aftertreatment (DATy orwere left permanently in the pot. The % retardation was assessed in each case at 21 days after treatment (DAT). The results are presented in Table Ill for a concentration of paclobutrazol of 0.05 and 0.5 mg/wick respectively.

TABLE III % Retardation at 21 DAT No of days after treatment when fibrous wick removed 1 7 14 permanent 0.05 mg/wick 16 1720 32 0.5 mg/wick 233034 32 EXAMPLE 3 This Example illustrates the use of a fibrous wick impregnated with a growth retardant (paclobutrazol) followed,forthe same plant, by fibrous wick impregnatedwith a growth promoter (gibberellic acid). The plants used weretomatoes grown in John Innes Potting Compost in 4 inch pots. In a duplicate set of experiments, fibrous wicks impregnated with 0.5 mg paclobutrazol were inserted into two sets of plants. At 14 days after treatment the wicks were removed and for one set of plantswere replaced by wicks impregnated with 0.5 mg of gibberellic acid. At 21 days after treatment the set of plants treated with paclobutrazol only showed 34% retardation (as compared with a blank) whilst the plants treated with paclobutrazol followed by gibberellic acid showed only 17% rntardation.

Claims

1. A plant growth regulating device adaptedfor use with containerized plants which comprises an elongated water-absorbent fibrous wick impregnated with a plant growth regulation composition.

2. A plant growth regulating device according to claim 1 wherein thefibre is cellulose diacetate fibre.

3. A plant growth regulating deviceaccordingto claim 1 or 2 wherein the fibres are aligned substantial- ly along the longitudinal axis of the wick.

4. A plant growth regulating device according to any of the preceeding claims wherein the fibrous wick contains between 0.05 mg and 5 mg ofthe active ingredient in the plant growth regulating composition.

5. A plant growth regulating device according toclaim 4wherein thefibrouswick contains between 0.1 mg and 0.5 mgofthe plant growth regulating composition.

6. A plantgrowth regulating device according to any ofthe preceeding claims wherein the length of the fibrouswick is between 3 cm and 20 cm and the diameter of the fibrous wick is between 1 mm and 10 mm.

7. Aplantgrowth regulating deviceaccordingto claim 6wherein the length ofthe fibrous wick is between 3cm and 15cm and the diameter of the fibrous wick is between 2 mm and 7 mm.

8. A plant growth regulating device according to any ofthe preceeding claims where the plant growth regulator composition contains as the active ingredient, paclobutrazol.

9. A method of regulating plant growth which comprises inserting intothe growing medium of a containerized plant one or more devices according to any of the preceeding claims.

10. A method of regulating plant growth acco rd- ing to claim 9 wherein one or more fibrous wicks are inserted into the growing medium to give a total charge of between 0.05 mg and 10 mg of active ingredient per containerized plant or plants.

11. Amethod of preparing a device according to any ofthe preceding claims wherein a solution of plant growth regulating composition in a suitabie organic solvent is applied to the fibrous wick.

12. A method of preparing a device according to claim 11 wherein the plant growth regulating composition contains as the active ingredient, paclobutrazor.

13. Amethod of preparing a device according to claim 11 wherein the organic solvent is isopropyl alcohol.