EP0379485A1 - Plant growth regulators - Google Patents

Abstract

The present invention relates to plant growth regulators and proposes the use of di-isopropyl-naphalene as a plant growth regulator for treating seeds, tubers and rhizomes (here called seeds) in order to delay the germination of seeds during the storage phase and / or to obtain rapid and vigorous germination and growth during the growth phase. The di-isopropyl-naphalenes can be formulated for application by any of the known methods for treating seeds of plants or growing media.

Description

"PLANT GROWTH REGULATORS"

This invention relates to plant growth regulators.

So called "Plant Growth Regulators" are well known in the field of agricultural chemicals but the term is often loosely applied to include fertilizers, pesticides, fungicides and the like plant food and plant protectors, frequently essential to assist healthy plant growth. The present invention is not concerned with such loosely termed materials and in this specification the term "Plant Growth Regulator" is used to define materials which regulate by delaying or accelerating the germinat ion of the seed or the growth of the plant .

Plant growth regulators are well known in the art and generally fall into three quite different and distinct groups. (i) Materials for preventing or delaying germination of the seed.

(ii) Materials for promoting or assisting propagation of the seed and, (iii) Materials for regulating the growth of plants.

Plant growth regulators for preventing or delaying the germination of seed are used primarily to store seed in good order for consumption or processing but most such materials which delay sprouting have an adverse effect on plants grown from the treated seed. Such "adverse affects" vary from delayed germination of the seed after planting to more serious effects and, by way of example, there are a number of materials which can be used to delay the sprouting of stored potatoes but in most countries such materials are banned for use on potatoes intended for seed.

Plant growth regulators for assisting the germination of seed generally comprise liquids or gels into which the roots of the germinating seed can grow but most such prior art plant growth regulators require the seed to be retained in the root growth material until a good root growth has been achieved, when the seed must be transplanted by hand to avoid damage to the root system. This method for seed propagation is expensive and is rarely used on plants other then relatively expensive ornamentals.

In the relatively small group of plant growth regulators applicable to growing plants some such regulators may be applied to the ground but not to the foliage of the plant whilst others may be applied to the foliage but not to the ground and most such prior art plant growth regulators available to date are so expensive that their use on commercial crops show little, if any, economic benefit. The present invention seeks to provide a plant growth regulator which can be formulated in various ways for application to seed; tubers and rizomes, hereinafter referred to as seeds, and to growing plants.

According to the present invention there is provided a plant growth regulator comprising di- isopropyl-naphthalene.

Di-isopropyl-naphthalenes are well known in the art and are used primarily as a solvent for duplicating inks. What has proved surprising is that this material, which from investigations todate has not been found in plant tissue, has most advantageous plant growth regulating properties.

Preferably the plant growth regulator proposed by the invention comprises an isomeric mixture of di- isopropyl-naphthalenes.

In one embodiment in accordance with the invention, the di-isopropyl-naphthalene is applied to an inert solids carrier, which may comprise a solids dust or granules. A most surprising characteristic of the di-isopropyl-naphthalenes is that whilst the material exhibits non-volatile properties, which would restrict its usage to contact applications, it has been found in practise that when applied to granules and mixed with seed the material affects seeds not in direct contact with the granules and thus appears to act in similar manner to a volatile material.

In another embodiment the di-isopropyl-naphthalene is combined with an emulsifying agent, such as phosphate ester.

In another embodiment in accordance with the invention the di-isopropyl-naphthalene is combined with a diluent, preferably an inert viscous material such as polyethylene glycol. The present invention also envisages a method for treating the seed or plants comprising the steps of applying to the seed, the plant or the growing medium for the seed or plant a di-isopropyl-napthalene or an isomeric mixture of di-isopropyl-naphthalenes.

In one preferred method in accordance with the present invention the di-isopropyl-naphthalene is applied to inert granular carriers which are mixed with the seed or distributed onto the growing medium for the seed or the growing plant.

In another method in accordance with the invention, for treating seed, the di-isopropyl-naphthalene is mixed with an emulsifying agent, is diluted with an inert diluent, and is applied to the seed by a dipping process,or by a spraying process such as by the use of a so-called ultra low volume applicator, or by a thermal or vapour fogging process.

In another method in accordance with the invention, for treating plants, the di-isopropyl-naphthalene, mixed with an emulsifying agent and diluted with an inert diluent, is applied to the plants by a spraying process.

The present invention thus identifies a single material which may be formulated in various ways and applied to seeds or growing plants or to the growing medium and the said regulator may be applied by any of the known methods for application, including soaking, liquid spray, fogging, dust, or by application to granules mixed with the seed or applied to the growing iaedium in which the plant is growing. Preferably the dosage rate for the plant growing regulator lies between 5 and 200 parts per million, more preferably between 10 to 50 parts per million.

The invention will now be described further by way of the following examples: EXAMPLE

1 litre of di-isopropyl-naphthalene was mixed with 50 ml. of an emulsifying agent namely a phosphate ester so as to produce a 92% wt/vol. solution. This formulation was then used to produce a dilution in water containing 100 parts per million of di-isopropl-naphthalene; twenty pea seeds were soaked in 100 ml. of this dilution for twenty four hours. The same number of pea seeds were soaked in pure water for the same length of time. Both groups of pea seeds were allowed to drain after immersion for thirty minutes before being placed on Whatman No. 4 filter paper in two petri dishes. Each batch was then covered with a 500 ml. beaker and placed in a warm light situation with the filter papers kept moist with distilled water. After 14 days root growth was assessed in both the treated and untreated group with the following results:-

TABLE A

Total root length, mm. Total root number

Control 1324 131

Treated 5351 170

% increase treatment 193 30

EXAMPLE 2

An emulsifiable concentrate made up as in Example 1 was diluted with polyethylene glycol to give a 1% wt./vol. dispersion of di-isopropyl-naphthalene.

100 ml. of the dispersion was applied to 50 kg. of Maris Bard seed potatoes, this being equivalent to a dosage rate of 20 parts per million of di-isopropyl-naphthalene, using a conventional ultra low volume spray applicator mounted on a roller table. The treated tubers were stored with a similar weight of untreated tubers in a controlled environment held at 5 degrees C. for 10 weeks followed by 2 weeks at 7 to 8 degrees C.

At the end of the twelve week period the tubers were examined and the sprout numbers and length recorded; the results are given in Table B.

TABLE B

Treatment Average number Average length sprouts/tuber of sprouts.

None 3 18.4 mm.

D.I.P.N. 4.8 11.3 The treatment significantly increased the number of sprouts and produced shorter and sturdier growth.

EXAMPLE 3

900 gms. of a granular diatomaceous earth with a particle size lying within the range 16 to 40 mesh, were sprayed with 100 gms of di-isopropyl-naphthalene within a revolving drum so as to produce a uniform distribution of the chemical within the granular matrix. 10 gms. of granules were applied to 10 kg. of potatoes of the cultivator Record on a chitting tray. Five such trays were prepared and stored with five trays of untreated potatoes.

Both lots were stored at 10 degrees C. for twelve weeks before measuring the sprout length on 20 tubers selected at random from each tray. The results were recorded as follows :-

TABLE C

TREATMENT Sprout length in mm average/ tuber

NONE 97 mm

D.I.P.N. 14 mm.

EXAMPLE 4

An emulsifiable concentrate produced as in Example 1 was diluted with water to give a dispersion containing 500 mg. per litre of the active ingredient D.I.P.N.

The liquid was then applied to 12 cucumber seedlings to "run-off" taking care not to allow the spray liquid to contact the growing medium, thereby to ensure that the take-up by the plant was restricted to the foliage.

After spraying the 12 treated plants were placed in a growing chamber with 12 untreated plants and 12 plants sprayed with plain water.

The plants were allowed to grow for three weeks after which time the growing medium was washed from the plants. After draining for 90 minutes the plants were weighed with the results given in table D.

TABLE D

TREATMENT Average root average root average leaf weight gms. number number

NONE 38,7 36.2 7.1

WATER 40.1 35.7 7.3

D.I.P.N. 59.5 46.2 9.1

EXAMPLE 5

An emulsifiable concentrate made up as in Example 1 was diluted with 200 mis. of water and applied to 100 kgs. of seed potatoes of the cultivar Pentland Squire, using an ultra low volume spray mounted on a roller table, giving a concentration of 2.5% wt/vol. of di-isopropyl- naphthalene or 50 parts per million.

The treated tubers and a similar quantity of untreated potatoes were stored in an insulated building maintained at 10 degrees C ± 2 degrees.

Artificial daylight was introduced to the store two weeks after the treatmentand after four weeks the tubers were planted in alternate rows.

The treatment was assessed on:- time to emergence; stem number; tuber number; tuber weight and final yield. The results are given in Table E.

TABLE E

Treated Untreated Diff.%

Days to 50 % emergence 11 17 54%

Average stem number 5.8 3.9 48%

Tuber number @ 98 days P.E. 18.0 12.5 44% Tuber weight @ 98 days P.E. 1475 gms. 825 gms. 78%

Tuber number @ 136 days P.E. 24.5 12.5 96%

Tuber weight @ 136 days P.E. 1735 gms. 1350 gms. 28%

Note: number of tubers and weights refer to single plant averages.

P.E. = Post Emergence.

EXAMPLE 6

1 kg. of di-isopropyl-naphthalene granules was made up as described in Example 3 and applied to a box containing 1 tonne of freshly harvested Pentland Squire.

The treated potatoes, with a 1 tonne box of untreated potatoes were then placed in a frost free building maintained at 5 degrees C ± 1 degree for 150 days, after which time the boxes were taken from store and the potatoes were graded. At that time no sprout growth had occured on the treated potatoes and the tubers were sound and firm. The untreated potatoes had grown sprouts in the order of 25% to 75 mm. 150 kgs. of treated potatoes and 150 kgs. of untreated potatoes lying within the size range 25 mm. to 50 mm. were placed in potato chitting trays and stacked in an illuminated and ventilated store for a further 30 days prior to planting.

The assessments made were as in Example 5 and the results are given in table F.

TABLE F

Treated Untreated Diff.%

Days to 50% emergence 10 17 70 Stem number/plant 6.0 3.9 53 Tuber/plant 21.5 11.4 88

Yield of marketable tubers

90 days P.E. 210 gms. 105 gms. 100 100 days P.E. 535 gms. 350 gms. 53

P.E. = Post Emergence

EXAMPLE 7

Cucumbers of the variety Telegraph were planted in growing bags after 5 plants had been sprayed to run-off naphthalene in water. Five similar plants were sprayed with water before planting. During the growing period the number of flowers produced and the yield of cucumbers was recorded and the results are shown in Table G.

TABLE G

Treated Control

Number of flowers 64 65 Number of cucumbers 22 17 Weight of cucumbers 7924 gms. 6712 gms.

EXAMPLE 8

Fresh harvested potatoes of the cultivar Pentland Squire were treated with 10 % wt/wt. D.I.P.N. granules at the rate of 1 kg. per tonne and stored in 1 tonne boxes. A comparative treatment of 10% wt/wt T.C.N.B. granules were applied to a number of boxes. Several untreated boxed were included as controls.

All of the boxes were stored in a frost free insulated store maintained at 5 degrees C ± 2 degrees C.

After 26 weeks storage the potatoes treated with D.I.P.N. granules were the only tubers free from sprout growth, as shown in Table H.

TABLE H Sprout growth mm. weight loss %

D.I.P.N. 0 3.7

T.C.N.B. 5-8 5.6

Control 15-25 8.2 EXAMPLE 9

Di-isopropyl-naphthalene was formulated as a 2% wt/wt dust and an emulsifiable concentrate containing 95% wt/vol active ingredient. The carrier used was fine diatomaceous earth.

Treatments were made to tubers as they were loaded into seed trays, each tray holding approximately 25 kg. of the cultivator Pentland Ivory.

All formulations were applied in accordance with the conventional dust application practise at a rate equivalent to 50 mg/kg. of active chemical Example 1 to tuber weight, on the 27th January, 1987.

All treatments and controls were stored in an insulated building maintained at 10 degrees centigrade ± 3 degrees. Artificial daylight was introduced to the store one month later. The tubers were then examined for sprout growth and the results are shown in table J.

TABLE J

Treatment Delay in sprouting Sprouting 50 days (days) after treatment No of sprouts (average of 25)

D.I.P.N. Spray 27 4.3 D.I.P.N. Dust 19 4.8 Untreated 3 3.4

All tubers were planted on 20th April, 1987, under good growing conditions in a chalky flint soil on the Lincolnshire Wolds and emergence is detailed in table K. TABLE X

Treatment Days to 50% emergence

D.I.P.N. Spray 11

D.I.P.N. Dust 10 Untreated 17

The early growth of both treatments was significantly better than the untreated crop but, the application of a mixture of contact and residual herbicide retarded all treatments more than the controls as a direct result of their earlier emergence. Three weeks later the plants from the treated seed were in advance of the untreated controls. A stem count was carried out 30 days and 50 days after planting and the results are shown in Table L.

Table L.

Stem number assessment

Treatment 30 days 50 days

D.I.P.N. Spray 7.1 5.9

D.I.P.N. Dust 6.0 5.8 Untreated 3.8 3.9

Example 1 above clearly shows that pea seeds treated with the plant growth regulator before planting showed a substantial increase in root length and root numbers and thereby a substantial increase in plant growth, relative to the untreated seed and after the treatment the seeds were capable of being sown by conventional planting apparatus.

Example 2 clearly show that the tubers, spray Example 2 clearly show that the tubers, spray treated with the plant growth regulator, experience a delay in sprout growth but showed a significant increase in sprout number and the sprout growths were sturdy. The treatment of the stored seed did not adversely affect the plant potential once the potatoes germinated.

Example 3 shows that the plant growth regulator when applied directly to granules and dispersed in a volume of potatoes clearly affected all the potatoes giving a substantial reduction in mean sprout length of the treated potatoes.

Example 4 clearly shows the advantages of applying the plant growth regulator to the foliage of growing plants, in the example cucumbers, as is evident from the increase in root number, root length and leaf growth relative to the controls.

Example 5 shows the effect of the di-isopropyl-naphalene/emulsifier/water combination sprayed on potatoes prior to planting and illustrates the very substantial reduction in time of emergence of the treated potatoes. In the trial all the treated potatoes had emerged and were well established before the first untreated potato emerged. The treated potatoes showed a substantial increase in stems, normally indicative of an increase in tuber numbers, and this was illustrated by the actual increase in tubers. It should also be observed that the number of usable tubers produced by the treated seed increased, as did the overall yield of treated seed.

Example 6 clearly shows the dual identity nature of the di-isopopropyl-naphthalenes.

When applied to potatoes under storage conditions, and note that the plant growth regulator was applied to granules, the plant growth regulator effectively delayed sprouting in the treated potatoes. When the treated potatoes, without further treatment, were exposed to germination conditions and planted the said treated potatoes showed substantially the same reduction in emergence time and increase in stem number, tubers/plant and increased weight of tubers as were exhibited in Example 5, wherein the plant growth regulator was applied to the tubers by contact application only shortly before planting. Example 7 is a further example illustrating the advantages of applying the plant growth regulator to the foliage of plants, in this example cucumbers.

Example 8 showed the di-isopropyl-naphthalene to be more efficient than T.C.N.B. as a sprout growth inhibitor and clearly showed a reduced loss of weight of the treated tubers.

Example 9 shows that the di-isopropyl-naphthalene proved to be effective when applied to an inert dust carrier. Whilst the present invention has been described by way of somewhat restricted examples such examples clearly show the beneficial effects of the plant growth regulator proposed by the present invention in the storage phase and the growing phase and, in disclosing trial results on three different groups of plant species, clearly shows the versatility of the di-isopropyl-naphthalenes on plant life forms in general.

Claims

1. A plant growth regulator comprising di-isopropyl-naphalene.

2. A plant growth regulator according to claim 1 comprising an isomeric mixture of di-isopropyl-naphalenes.

3. A plant growth regulator according to claim 1 or 2 in combination with an inert granular carrier.

4. A plant growth regulator according to calim 1 or 2 in combination with an inert powder carrier.

5. A plant growth regulator according to claims 1 2 or 4 in combination with an emulsifying agent.

6. A plant growth regulator according to claims 12 or 5 in combination with a diluent.

7. A plant growth regulator according to claim 6 in which the diluent comprises an inert viscous material.

8.. A method for treating seed or plants comprising the steps of applying to the seed, the plant or the growing medium for the seed or plant a plant growth regulator according to any one of the preceding claims.

9.. A method according to claims 8, in which the dosage rate for the plant growth regulator comprises from 5 to 200 parts/million by weight .

10. A method as claimed in claim 8 or 9 in which the dosage rate for the plant growth regulator comprises from 10 to 50 parts/million by weight.