Disclosed are salts of gibberellin with amines which are secondary or tertiary aryl or alkylamines having 16 to 36 carbon atoms, said salts being more effective as plant growth regulants than gibberellin per se and capable of being employed in ultra-low-volume applications.

This invention relates to certain gibberellin salts, to compositions 
containing them and to a method of regulating plant growth using them. 
The gibberellins are a group of plant growth regulators derived from 
cultures of the fungus Gibberella fujikuroi (for a description of these 
substances, see Grove, Quarterly Reviews, 1961, 15, 56-71). The 
gibberellins include, for example, gibberellin A.sub.3 (or gibberellic 
acid) disclosed in British Patent Specification No. 783,611, gibberellin 
A.sub.4 and gibberellin A.sub.7 (the latter being disclosed in British 
Patent Specification No. 914,893), the disclosures of both these 
Specifications being incorporated herein by reference. The Specifications 
also disclose the preparation of ammonium, alkali metal and alkaline earth 
metal salts of gibberellins A.sub.3 and A.sub.7. 
Gibberellin A.sub.7 is obtained commercially as a mixture with a varying 
(e.g. an equal) proportion of gibberellin A.sub.4, in which form it is 
generally used for plant growth regulating purposes. Gibberellins A.sub.3 
and A.sub.4 /A.sub.7 are conveniently applied to plants in the form of 
compositions in which the active ingredient is mixed with a diluent or 
carrier. Examples of such compositions include aqueous solutions, and 
solutions in organic solvents. 
Gibberellins are effective at low rates of application. However, they have 
to be made by slow and difficult fermentation methods, and are in 
consequence expensive. We have now discovered a way of applying 
gibberellins which, for some purposes at least, enables a lower rate of 
application to be used effectively with a consequent saving in cost. The 
application of reduced volumes of liquid becomes possible and this is of 
particular value where aerial spraying is used. 
The invention provides a salt of a gibberellin with an amine having at 
least 8, for example 8 to 40, carbon atoms. It also provides a plant 
growth regulating composition comprising the gibberellin salt and a 
carrier, e.g. an organic solvent. Further, the invention provides a method 
of regulating the growth of a plant, which method comprises applying to 
the plant, or to the locus of the plant, a composition as defined above at 
a rate of 0.5 to 50 liters of solution per hectare. 
The amine can be a primary, secondary or tertiary amine in which the 
nitrogen atom may be attached to an aliphatic, alicyclic, aromatic or 
heterocyclic residue and may itself form part of a heterocyclic ring. The 
amine can be an alkylamine or arylamine. Preferred amines have 16 to 36 
carbon atoms; conveniently they are secondary or tertiary alkylamines, for 
example trinonylamine, disoyaamine, dicocoamine and dimethylcocoamine. 
Dicocoamine is a commercially available mixture of secondary alkylamines 
manufactured from the mixed fatty acids of coconut oil, the bulk of the 
mixed alkylamines having C.sub.12, C.sub.14 or C.sub.16 alkyl moieties. 
Examples of suitable arylamines are diphenylamine, m-toluidine, aniline 
and N-methylaniline. 
The gibberellin is suitably gibberellin A.sub.1, gibberellin A.sub.3, 
gibberellin A.sub.9, gibberellin A.sub.4, gibberellin A.sub.7 or a mixture 
of gibberellin A.sub.4 and gibberellin A.sub.7. 
The salts may be prepared by reacting (for example at room temperature 
(17.degree. C. to 70.degree. C. and for up to 1 hour) the gibberellin with 
the amine, for example (a) by dissolving the gibberellin in a suitable 
solvent, e.g. methanol, with gentle heating if required, separately 
dissolving the amine in a suitable solvent (e.g. methanol or chloroform), 
mixing the two solutions, and evaporating the mixture to dryness, or (b) 
by dissolving the amine in a solvent such as methylene chloride, mixing 
with stirring the gibberellin in solid form with the solution and 
evaporating the mixture to dryness. The evaporation is preferably 
performed under relatively low pressure (by about 0.1 Torr) since 
otherwise the salt is obtained in a rather waxy and sticky form. 
The compositions can be of two kinds: concentrates suitable for sale to the 
user, and more dilute formulations which are generally prepared by the 
user shortly before he applies them to the plants. The concentrates 
conveniently comprise a solution of 0.1 to 30%, for example 1 to 30% and 
preferably 5 to 20%, of a salt of the invention in an organic solvent, for 
example an optionally substituted cyclohexanone (e.g. cyclohexanone itself 
and the monomethylcyclohexanones), isophorone, butanol, vegetable oils 
(e.g. cotton seed oil) and Aromasol H (a mixture of trimethylbenzenes), 
and mixtures thereof with polyethylene glycol, and optionally a surface 
active agent. All solvents are not equally suitable for all salts of the 
invention; some salt/solvent combinations (e.g. those illustrated in the 
Examples hereafter) are better than others. 
The concentrates may be diluted prior to use, e.g. with water and/or a 
non-phytotoxic organic solvent. The resulting diluate may be in the form 
of a solution or an emulsion. If they are to be diluted with water, they 
should contain a surface-active agent to assist in the formation of a 
homogeneous and stable emulsion. They may be diluted with non-phytotoxic 
organic solvents, whether or not they contain surface-active agents, to 
form solutions. The preferred solvents are the vegetable oils, for example 
olive oil, corn oil, cotton seed oil, castor oil, soya-bean oil and 
especially groundnut oil, also known as arachis or peanut oil. 
Examples of suitable surface-active agents are a condensate of 
p-nonylphenol with 7 to 8 moles of ethylene oxide (sold as Lissapol NX), a 
condensate of ethylene oxide with octyl phenol (sold as Lubrol E) and a 
condensate of ethylene oxide with propylene oxide polymer (sold as 
Pluronic L61). 
It is preferred to apply the compositions to the plants at a rate of 1 to 
50, particularly 2 to 10, liters of solution per hectare. This method is 
an adaptation of the so called ULV (ultra-low volume) application 
technique. This is a known method of applying insecticides, but has not 
hitherto found frequent application in the regulation of plant growth. 
Previously, plants have usually been sprayed for growth regulation purposes 
at volumes of 200 to 5,000 liters per hectare, two orders of magnitude 
greater than the volumes used in the method of the present invention. 
Advantages of the use of lower spray volumes include lower water use, with 
less bulky and sometimes less complex spraying apparatus. Spraying can be 
carried out faster and more economically. Because the volume of spray to 
be applied is so much lower, it becomes a practical possibility to spray 
some crops from the air. In some cases, plant uptake of the gibberellins 
from concentrated solutions is better than from dilute solutions, and 
sometimes penetration of plant tissue may also be improved; such 
improvement may be due both to the use of the more concentrated solution 
and to the liquid solubility of the salts. 
The compositions can if desired be sprayed on to plants using the so-called 
electrodynamic spraying technique. A suitable apparatus for this technique 
is disclosed in British Patent Application No. 29539/76, the disclosure of 
which document is incorporated herein by reference. 
Rates of application of the gibberellin vary according to the plants being 
treated and the effect sought thereby. Suitable rates are 5 to 200 grams, 
for example 10 to 200 grams, of gibberellin salt per hectare, though 
sometimes amounts as low as 1 gram per hectare may give useful results. 
The compositions may additionally comprise other plant growth regulating 
substances, particularly the auxins (e.g. indol-3-yl-acetic acid, 
indol-3-yl-butyric acid, 1-naphthylacetic acid and 2-naphthoxyacetic 
acid), the hormone herbicide such as 2,4-D and 2,4,5-TP, and the 
cytokinins e.g. kinetin (furfurylaminopurine), benzimidazole, 
benzyladenine (6-benzylaminopurine) and N,N'-diphenylurea. 
The uses of gibberellins in agriculture are numerous and diverse. Both 
monoctyledenous and dicotyledenous plants may be treated. The following 
are among the crops which have been treated with gibberellins to obtain a 
variety of useful effects: pears, grapes, rhubarb, oil-palm, oranges, 
watercress, artichokes, bananas, tea, coffee, sugar-cane and pasture grass 
(e.g. Pangola grass or Kikuyu grass). Attention is drawn to the review by 
Turner, Outlook on Agriculture, 1972, Volume 7, Number 1, pages 14 to 20, 
and various papers in Outlook on Agriculture, 1976, Volume 9, Number 2, 
the disclosures of which documents are incorporated herein by reference. 
There now follows a list of examples of the effects that gibberellins can 
have on plants. 
(1) Increasing vegetative growth particularly on plants under low 
temperature constraint (examples of plants where this effect can be 
noticed are the pasture grasses), 
(2) Breaking of vegetative dormancy (tea, pasture grasses), 
(3) Modifying flowering and fruiting patterns (coffee, citrus fruits, 
conifer seed production), 
(4) Improving fruit setting, e.g. increasing parthenocarpic setting (citrus 
fruits, pears, apples, grapes), 
(5) Delaying ripening and senescence (citrus fruits, bananas, tomatoes), 
and 
(6) Improving fruit development (seedless grapes).

The following Examples illustrate the invention. All parts and percentages 
are by weight and all temperatures degrees Centigrade, except where 
otherwise stated. 
EXAMPLE 1 
Gibberellin A.sub.3 (1 mole) was dissolved in warm methanol. Trinonylamine 
(1 mole) was dissolved in chloroform. The solutions were mixed. The 
solvents were evaporated from the resulting mixture and the residue dried 
to give the trinonylamine salt (yield 95%), m.p. 102.degree.-106.degree.. 
EXAMPLE 2 
Example 1 was repeated, substituting Armeen 2HT for trinonylamine. Armeen 
2HT is a commercially available mixture of secondary amines derived from 
hydrogenated tallow fats, containing principally the alkyl radicals 
C.sub.16 H.sub.33 and C.sub.18 H.sub.37. The Armeen 2HT salt, m.p. 
60.degree.-75.degree., was prepared in 95% yield. 
EXAMPLE 3 
This Example illustrates the preparation of the Armeen 2C salt of 
gibberellin A.sub.3. Armeen 2C is a commercially available mixture of 
secondary alkyl amines derived from coconut oil, containing principally 
C.sub.12 H.sub.25, lesser amounts of C.sub.14 H.sub.29 and minor amounts 
of higher alkyl moieties up to C.sub.18. 
Gibberellin A.sub.3 (1 mole) was dissolved in warm methanol to give a 5% 
solution. Armeen 2C (1 mole based on its quoted average molecular weight 
of 390) was dissolved in methanol to give a 5% solution. The solutions 
were combined and the methanol removed by evaporation to give the salt 
(yield 95%), m.p. 80.degree.-85.degree.. 
EXAMPLE 4 
The following concentrate was prepared. 
______________________________________ 
Salt of Example 1 21.5% 
Lissapol NX 10.0% 
Sextone B (mixture of monomethylcyclo 
hexanones, technical grade) 
68.5% 
______________________________________ 
EXAMPLE 5 
The following emulsifiable concentrate was prepared. 
______________________________________ 
Salt mixture of Example 2 
12.2% 
Lubrol E 5.0% 
Aromasol H 82.8% 
______________________________________ 
EXAMPLE 6 
This Example illustrates a concentrate suitable for use, after dilution 
with vegetable oil for spraying on plants. 
______________________________________ 
Salt of Example 3 10.48% 
Cyclohexanone 44.76% 
Polyethylene glycol (mean molecular 
weight 200) 44.76% 
______________________________________ 
The specific gravity of the concentrate is 1.038. 
EXAMPLE 7 
This Example illustrates a composition suitable for use by the 
electrodynamic spraying technique. 
The following concentrate was prepared. 
______________________________________ 
Salt of Example 3 0.214% 
Cyclohexanone 20% 
N-methylpyrrolidone 20% 
Cotton seed oil up to 100% 
______________________________________ 
This concentrate was diluted with a mixture of N-methylpyrrolidone (20%), 
Isopar L (an isoparaffin solvent; 17.4%) and cotton seed oil (to 100%) to 
give a composition containing varying amounts (0.1 to 100 p.p.m.) of 
gibberellin. 
Examples 8 and 9 illustrate the method of the invention applied to oranges. 
Growers frequently spray Navel orange fruits with gibberellin A.sub.3 
(GA.sub.3) to improve skin quality and delay ripening. Such treatment 
results in a firmer rind which is less liable to mechanical damage and 
causes a delay both in rind colouring and the onset of rind puffiness and 
other physiological degenerative conditions. This results in improved 
quality in fruits picked late in the harvesting season. 
EXAMPLE 8 
Trees of a variety of early Navel orange (Thompsons Navel) in Valencia, 
Spain, bearing fruits at an early stage of ripening (the rinds were just 
turning from green to yellow) were sprayed with GA.sub.3 at a rate 
equivalent to 100 g/ha. The compound was formulated in two ways: 
Formulation A for purposes of comparison and Formulation B according to 
the invention. 
Formulation A 
Solid pure GA.sub.3 was dissolved in a little acetone/ethanol, adding water 
to form an aqueous solution. Alkylphenol/polyoxyethylene condensate wetter 
was added to the water so that when the GA.sub.3 solution was made up to 
final volume the concentration of wetter was 0.1%. 
Formulation B 
An appropriate quantity of the emulsifiable concentrate of Example 5 was 
diluted with olive oil to make up the volume to the quantity required for 
spraying. 
Both formulations were each applied to six separate orange trees with a low 
volume spray applicator at a volume equivalent to 20 liters/ha and in a 
manner which ensured dispersion of the fine spray droplets over the 
foliage and fruits on the full circumference of each tree. The fruits on 
12 other trees were retained untreated as controls. Treatments and 
controls were sprayed onto trees in a randomised block experimental 
design. 
99 Days after spraying, fruits were picked from treated and control trees. 
A measure of the skin hardness of 10 fruits taken at random from each 
replicate tree was obtained by a penetrometer test which measures the 
force in grams needed to push a standard needle at constant speed through 
the rind of each orange at one spot on the equator. The results in Table I 
show that the rinds of oranges treated with each Formulation were 
significantly harder than the rinds of control fruits, but that the fruits 
treated with Formulation B had significantly harder skins than the skins 
of fruits treated with Formulation A. 
TABLE 1 
______________________________________ 
PENETROMETER 
TREATMENT READING (g) 
______________________________________ 
Formulation A (100 g/l of 
GA.sub.3) 312 
Formulation B (100 g/l of 
GA.sub.3) 361 
Control, untreated fruits 
269 
______________________________________ 
EXAMPLE 9 
In another experiment conducted in Spain, Washington Navel Orange trees 
were sprayed with GA.sub.3 formulations just before the fruits were 
expected to ripen and change colour from green to orange. The GA.sub.3 was 
applied at rates equivalent to 40 and 80 g/ha. Three GA.sub.3 formulations 
were used. Formulations A and B of Example 8 and 
Formulation C 
an appropriate quantity of the 10% emulsifiable concentrate formulation 
described in Example 4 was treated with olive oil to make up the volume to 
the quantity required for spraying. 
Formulation A was sprayed on 6 trees at 40 g/ha and at 80 g/ha of GA.sub.3 
in a volume equivalent to 2000 liters/ha. High volume sprays of aqueous 
preparations of GA.sub.3 such as this are normally used by citrus growers 
for treating Navel orange fruits. 
Sprays of GA.sub.3 were also applied at 20 liters/ha. For these 
applications, Formulations A and B (sprayed at 40 g/ha and 80 g/ha) and 
Formulation C (sprayed at 80 g/ha) were used. Each treatment was applied 
to the foliage and fruits on 6 separate orange trees. 
Both high and low volume applications, together with the other treatments, 
were arranged in a randomised block design in which there were 12 
untreated control trees. 
48 Days and 103 days after the trees were sprayed, 40 fruits were picked at 
random from each of the treated control trees. The colour of each fruit 
was assessed and recorded on the following scale. 
1=orange 
2=orange-yellow 
3=yellow 
4=yellow with a green tinge 
5=midway between yellow and green 
The average colour grades of each of the experimental treatments is given 
in Table 2 below. 
These results show that at both harvest dates, Formulation B sprayed at 40 
g/ha and 20 l/ha caused the rinds of Navel orange fruits to be 
significantly yellower in colour (indicating delayed skin ripening) than 
the rinds of fruits treated with Formulation A at 40 or 80 g/ha and at 
2000 l/ha. 
At the second harvest, Formulations B and C gave significantly paler 
coloured fruits than equivalent rates of aqueous GA.sub.3 applied at 20 
g/ha or 2000 l/ha. 
Formulation B applied at 40 g/ha and 20 l/ha gave results at both harvests 
equivalent or significantly superior to the results obtained by 
applications of aqueous GA.sub.3 at double the rate per hectare applied at 
20 or 2000 l/ha. 
TABLE 2 
______________________________________ 
MEAN 
RATES COLOUR GRADES 
g/ha After After 
FORMULATION 1/ha OF GA.sub.3 
48 DAYS 103 DAYS 
______________________________________ 
Formulation A 
2000 40 3.25 2.11 
Formulation A 
2000 80 3.18 2.14 
Formulation A 
20 40 3.38 2.10 
Formulation A 
20 80 3.55 2.21 
Formulation B 
20 40 3.75 2.28 
Formulation B 
20 80 3.83 2.46 
Formulation C 
20 80 3.90 2.47 
Untreated controls 
-- -- 2.16 1.89 
______________________________________ 
EXAMPLE 10 
This Example illustrates the treatment of monocotyledonous plants to 
increase rate of growth, and the increased effects obtainable with the 
compositions of the invention as compared with known compositions. 
Dwarf maize (Zea mays; variety D5, an F1 hybrid) was grown in pots in the 
glasshouse. There were two treatments, D and E, and an untreated control, 
each with five replicate plants. For treatment D, GA.sub.3 tablets were 
dissolved in water with the addition of 0.025% w/v 
alkylphenol/polyoxyethylene condensate wetter, to give a solution 
containing 10 p.p.m. GA.sub.3. This was applied to the maize through a 
standard spraying nozzle at a rate equivalent to 500 l/ha, giving a 
calculated application rate per plant of 0.5 .mu.g GA.sub.3. For treatment 
E, the formulation of Example 6 was dissolved in groundnut oil to give a 
solution containing 1000 p.p.m. GA.sub.3. This was applied to the maize by 
a spinning disc applicator at 10 l/ha giving a calculated application rate 
per plant of 0.51 .mu.g GA.sub.3. The gibberellin response of the maize 
plants was assessed by measuring the first internode (distance between 
first and second ligule) 6, 8 and 13 days after spraying. The results in 
Table 3 show notably greater activity for treatment E according to the 
invention than treatment D according to the prior art. At 6 days, plants 
treated by treatment E also showed the second internode. This did not 
appear in the other plants until 8 days. No treatment showed any 
phytotoxicity or other abnormality. 
TABLE 3 
______________________________________ 
Mean Internode Length (mm) 
Treatment Treatment 
Days After Treatment 
Control D E 
______________________________________ 
6 7.2 9.2 23.6 
8 8.0 11.6 25.6 
13 11.4 15.8 29.2 
______________________________________ 
EXAMPLE 11 
This Example illustrates the increased effects obtained with the salts of 
the invention on a monocotyledonous plant growing under field conditions. 
It is well known that the growth of some tropical pasture grasses is 
greatly reduced by low night temperatures and that such reductions can be 
partly overcome by the application of gibberellic acid (Whitney, Agronomy 
J., 1976, 68, 365-370, the disclosure of which document is incorporated 
herein by reference). 
Comparative tests were conducted on farm pastures of pangola grass 
(Digitaria decumbens) at two locations in Florida, USA. Treatments were 
performed in November when growth was retarded. Gibberellic acid was 
formulated in two ways. Formulation A for purposes of comparison and 
Formulation B according to the invention. 
Formulation A 
GA.sub.3 as the water soluble commercial formulation `Berelex` was 
dissolved in water to give solutions of the required concentrations. 
Alkylphenol/polyoxyethylene condensate wetter was added to the water to 
give a concentration of 0.1% in the final volume. 
Formulation B 
Appropriate quantities of the concentrate of Example 6 was diluted with 
corn oil to give solutions of the required concentrations. 
Both formulations were applied at three different concentrations. In all 
cases, Formulation A was applied in a volume equivalent to 500 
liters/hectare while Formulation B was applied in a volume equivalent of 5 
liters/hectare. Each treatment was applied to six replicate plots each 39 
m.sup.2 in area. Treatment and control plots were distributed in a random 
block experimental design. Before treatment, all the plots were mowed to a 
uniform height and dressed with ammonium nitrate fertiliser at a rate 
equivalent to 56 kg/hectare. 
36 Days after spraying the plots were mowed and the fresh weight of the 
clippings determined. 
The results in Table 4 show that on site 1 Formulation B was at least three 
times as effective as Formulation A. On site 2 Formulation B was about 1.5 
times as effective as Formulation A. 
TABLE 4 
______________________________________ 
FRESH WEIGHT YIELD OF PANGOLA GRASS 
SITE 1 SITE 2 
TREATMENT kg/m.sup.2 
% kg/m.sup.2 
% 
______________________________________ 
Formulation A 24 g/ha 
0.246 120 0.610 147 
Formulation A 48 g/ha 
0.327 159 0.688 165 
Formulation A 96 g/ha 
0.359 175 0.852 205 
Formulation B 12 g/ha 
0.307 150 0.636 153 
Formulation B 24 g/ha 
0.344 167 0.665 160 
Formulation B 48 g/ha 
0.455 221 0.770 185 
Control 0.206 100 0.416 100 
______________________________________ 
EXAMPLE 12 
This Example illustrates the application to tomatoes of the diphenylamine 
and trinonylamine salts of gibberellic acid as low volume sprays in 
groundnut oil. 
The diphenylamine and trinonylamine salts of GA.sub.3 were prepared as 
solutions in propylene glycol containing 5% w/v GA.sub.3 equivalent. These 
solutions were formulated in groundnut oil as secondary carrier to give 
solutions containing active ingredient at the equivalent of 150 and 350 
.mu.g/ml of GA.sub.3. They were sprayed onto tomato plants at a volume 
equivalent to 10 l/ha, using an Aerograph Super 63 air brush, model E-504, 
at 2.0 atmospheres. This is equivalent to 15 and 35 g/ha of GA.sub.3. 
These treatments were compared with treatments using solutions of GA.sub.3 
prepared by dissolving the requisite amounts of GA.sub.3 in a few drops of 
ethanol and then further diluting the solution with larger volumes of 
water to give preparations containing 1.5 and 3.5 .mu.g/ml of GA.sub.3. 
These aqueous formulations were sprayed at 1000 l/ha using an Aerograph 
DeVilbiss Type MPS spray gun at 1.4 atmospheres. 
The tomatoes (variety Sutton's "Best of All") used for the experiment were 
propagated in 10 cm diameter plastic pots using a peat/sand compost. Ten 
such plants were used per treatment; 10 untreated plants were used as 
controls. They were sprayed at 35 days after sowing. Plants were arranged 
randomly within blocks, one replicate of each treatment per block. The 
stem length of each plant was measured from the cotyledons to the growing 
point immediately prior to spraying and again 7 days afterwards. The 
results in Table 5 show increases in stem length over this 7 day period 
for treated and untreated plants. Greater increases in stem length were 
obtained by spraying GA.sub.3 in the form of the amine salts in oil, 
rather than as the free acid in water. 
TABLE 5 
______________________________________ 
Height 
Increase 
(mm)At 
15 35 
g/ha g/ha 
______________________________________ 
Diphenylamine salt in propylene glycol + 
55 66 
groundnut oil 
Trinonylamine salt in propylene glycol + 
62 72 
groundnut oil 
GA.sub.3 free acid in dilute aqueous ethanol* 
47 53 
Untreated control 40 
______________________________________ 
Least significant difference between treatment means: 
P = 0.05 : 6.0? 
P = 0.01 : 7.9 
*The addition of a wetter to this composition could improve the height 
increase figures.