DK158350B - PLANT GROWTH REGULATORY 2-PYRIDONES AND METHOD FOR REGULATING PLANT GROWTH - Google Patents

Description

in

DK 158350B

The present invention relates to novel plant growth regulating 2-pyridones, in particular for inducing male sterility in cereal plants and a method for regulating plant growth in a cereal plant.

The plant growth regulating 2-pyridones of the invention are inherently judgmental in that they have the general formula R3 10 e4V ^ Vr2 10 (I)

A N

R5 is wherein R 1 is C (14) alkyl R 1 is carboxy (or an agronomically acceptable salt thereof) or carb (C 14) alkoxy, R 3 is hydrogen or (C 1) alkyl, 4 R is hydrogen, (C 2 4) represents phenyl substituted with 1 or 2 identical or different substituents selected from halogen, (C 1-6 alkyl, (C 1-6 alkoxy and trifluoromethyl, or naphthyl substituted with up to two identical or different halogen atoms).

25

From the disclosure of U.S. Patent No. 3,761,240, compounds having gametocide action are known which, unlike the compounds of the invention, have a carboxy group or a derivative thereof in the 3-position, rather than in the 5-position. However, the known compounds have the effect of producing considerable shaft length inhibition. Surprisingly, it has been found that this side-effect inhibition side effect is practically avoided when the carboxy group or derivative thereof is moved from the 3-position of the compounds to their 5-position.

Among the 2-pyridones of formula I, the compounds wherein Rg represents phenyl substituted with 1 or 2 halogen atoms are preferred. Particularly preferred are those compounds in which R bet represents methyl, Reg represents carboxy or an alkali metal salt thereof, Rg represents hydrogen or methyl, R ^ represents hydrogen, and Rg represents phenyl substituted with 2

DK 158350B

chlorine or bromine, especially 4-bromophenyl.

The invention further relates to a process for regulating plant growth in a cereal plant which is characterized by adding to the growing plant, plant seeds or antioquality an effective amount of a compound of the general formula I. The compound is preferably fed to the growing plant. prior to meiosis and in an amount effective to induce male sterility in the plant.

When R represents a salt of a carboxy group, an alkali metal, a terrestrial potassium metal or a transition group metal can provide the cation.

The cation may also be ammonium or substituted ammonium. Representative metal salt cations include all potassium cations such as sodium, potassium, lithium or the like, terrestrial potassium cations such as calcium, magnesium, barium, strontium or the like, or heavy metal cations such as zinc, manganese, cupri, cupro, ferric, ferrous, titanium, aluminum or the like. Among the ammonium salts are those wherein the ammonium cation has the formula NZ * Z 2 Z 3 Z 2, wherein each Z 1, Z 2, Z 3 and Z 2 individually represents a hydrogen atom, a hydroxy group, a (C 14) alkoxy group, a (C 130) alkyl group, a (C 3 alkenyl group, a (C38) al cynyl group, a (C28) hydroxyalkyl group, a (C28) alkoxyalkyl group, a (C2 6) aminoalkyl group, a (C2-6) haloalkyl group, a substituted or unsubstituted phenyl group , a substituted or unsubstituted phenyl alkyl group having up to 4 carbon atoms in each coolant one, an amino or allkyl substituted amino group, or any two of the groups 1,1,1 and Z may together with the nitrogen atom form a 5- or 6-membered heterocyclic ring, optionally with up to a further heterooxygen, nitrogen or sulfur atom in the ring, and preferably a saturated ring such as a piperidine, morpholine, pyrrolidine or piperazine ring or the like. Or, any of the 12 3 4 groups 1,1,1 and Z may together with the nitrogen atom form a 5- or 6-membered aromatic heterocyclic ring, such as a pyrazole or pyridine ring. When the ammonium group contains a substituted alkyl, substituted phenyl or substituted phenyl alkyl group, the substituents will usually be selected from halogen atoms, (C 1-8) alkyl groups, (C 1-8) alkoxy groups, hydroxy groups, nitro groups, trifluoromethyl groups, amino groups, (Cj_4) alkyl groups and the like. Preferably, such substituted phenyl groups have up to 2 such substituents. Representative ammonium cations include ammonium, dimethylammonium, 2-ethyl hexyl ammonium, bis (2-hydroxyethyl) ammonium, tris (2-hydroxyethyl) ammonium, dicyclohexylammonium, t-octyl ammonium, 2-hydroxy

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3 ethyl ammonium, morpholinium, piperidium, 2-phenethylammonium, 2-methylbenzylammonium, n-hexyl ammonium, triethyl ammonium, trimethylammonium, tri (n-butyl) ammonium, methoxyethylammonium, di isopropyl ammonium, pyridinium, di allyl ammonium, pyrazolium, propargylammonium, dimethylhydrazonium, hydroxyammonium, methoxyammonium, dodecylammonium, octadecylammonium, 4-dichlorophenylammonium, 4-nitrobenzylammonium, benzyltrimethylammonium, 2-hydroxyethyl ethyl ammonium, 4-methylbenzyltrimethylammonium and the like.

Among the substituents which R may contain and which may be the same or different are alkyl groups of up to 4 carbon atoms, alkoxy groups of up to 4 carbon atoms, halogen atoms such as fluoro, chloro, bromo and in oatoms, and trifluoromethyl.

The most preferred substituents are halogen atoms, preferably with at least one at the 4-position, (Cj _) alkyl groups, preferably 4-methyl, (Cj _) alkoxy groups, preferably 4-methoxy and trifluoromethyl groups, preferably 4-trifluoromethyl.

Typical compounds of formula I include: N- (4-chlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (3-chlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one one, N- (4-bromophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (2-chlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (4 -i-Odphenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (2-fluorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (4-trifluoromethylphenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (4-methoxyphenyl) -5-carboxy-4,6-dimethylpyrid-2-one, N- (4-chlorophenyl) -5-carboxy-6 -methylpyrid d-2-one, N- (3-ethoxyphenyl) -5-carboxy-6-methylpyrid-2-one, N- (4-methylphenyl) -5-carboxy-6-methylpyrid-2-one, 30 N - (3,4-dichlorophenyl) -5-carboxy-6-methylpyrid-2-one, N- (4-methyl-3-chlorophenyl) -5-carboxy-6-methylpyrid-2-one, N- (4- chlorophenyl) -5-carboxy-3,4,6-trimethylpyrid-2-one, N- (4-bromophenyl) -5-carboxy-4,6-diethylpyrid-2-one, N- (4-chlorophenyl) -5 -carboxy-4,6-diethylpyrid-2-one, N- (4-bromophenyl) -5-carboxy-4,6-dipropylpyrid-2-one, N- (4-chlorophenyl) -5-carboxy-4-one ethyl-6-methylpyrid-2-one, N- (4-trifluoromethylphenyl) -5-carboxy-6-ethyl-4-methylpyrid-2-one, N- (4-chlorophenyl) -5-carboxy-6-ethylpyrid-2-one,

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4 N- (4-bromophenyl) -5-carboxy-6-propylpyrid-2-one, N- (4-chlorophenyl) -5-carboxy-3,6-dimethylpyrid-2-one, N- (4-tri fluoromethylphenyl) -5-carboxy-3,6-dimethylpyrid-2-one, N- (4-bromophenyl) -5-carboxy-6-methylpyrid-2-one, 5N- (3,4-dichlorophenyl) -5 -carboxy-4,6-dimethyl pyrid-2-one, N- (2-chloro-4-methylphenyl) -5-carboxy-4,6-dimethylpyrid-2-one, 3-bromo-N- (4-chlorophenyl) ) -5-carboxy-4,6-dimethylpyrid-2-one, 3-bromo-N- (4-fluorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, 3-chloro-N- (2) (4-Dichlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, 3-fluoro-N- (3-chlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one, 3-bromo -N- (4-trifluoromethylphenyl) -5-carboxy-6-methylpyrid-2-one, and agronomically acceptable salts of the above acids, N- (4-chlorophenyl) -5-carbomethoxy-4,6-dimethylpyrid-2-one , N- (4-fluorophenyl) -5-carbethoxy-4,6-dimethylpyrid-2-one, N- (3-methylphenyl) -5-carbobutoxy-4,6-dimethylpyrid-2-one, and N- (3 , 4-dichlorophenyl) -5-carbethoxy-6-methylpyrid-2-one.

Although the compounds of formula (I) can be prepared by a method known per se, e.g. As described in the literature 20 for the preparation of analogous compounds, convenient reaction pathways are set forth hereinafter.

In a first process, an acid chloride of the formula (Π) is condensed: R3 R6 25 / II (II) H COC1 fi n wherein R represents a hydrogen atom or an alkyl group and R has the meaning defined above, with an enamine with Formula (III): 30 ro2c r1 hK 5 (III) H NHR * 15 wherein R represents (C1-4) alkyl and R and R have the meaning defined above to produce a dihydropyridone of formula (IV): 5

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"S

r3 (IV)

5 ° XfV

R

1 o c g wherein R, R, R, R and R have the meaning defined above. This reaction is usually carried out in an inert solvent, such as ethyl ether, methylene chloride, benzene or toluene, at a temperature of 0-100 ° C. The dihydropyridone is then dehydrogenated in the presence of a dehydrogenating agent such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or a similar quinone, charcoal palladium or N-bromosuccinimide. The dehydrogenation reaction is usually carried out in an inert solvent such as benzene, xylene or chlorobenzene and at a temperature of 50 ° C - 250 ° C to form a pyridone of formula (V): R3 CO 2 R (V) R 5 13 5 6 25 wherein R, R, R, R and R have the meaning defined above. The ester can then be converted to the corresponding acid or salt by conventional hydrolysis, e.g. using an agent such as sodium or potassium hydroxide, potassium or the like, at ambient or elevated temperatures of up to 100 ° C.

In another reaction path leading to compounds of the invention, a pyrone of formula (VI) is reacted: R3 ^ Ν ^ ° 2Ε (VI)

35 XI

1 3

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6 wherein R, R and R are as defined above with an amine of formula (VII): NH 2 -R5 (VII) wherein R is as defined above. This reaction is usually carried out in the presence of an acid catalyst such as p-toluene sulfonic acid, methanesulfonic acid, hydrochloric acid or sulfuric acid, in an inert solvent such as chlorobenzene, toluene, xylene or cumene, or using 50% aqueous acetic acid as the reaction medium. formation of a pyridone of formula (VIII): wherein R, R, R and R have the meaning defined above. The reaction is usually carried out at a temperature of 50 ° C - 250 ° C. The free acid and its salts can then be prepared by conventional techniques.

4

The compounds of formula I wherein R represents a halogen atom can be prepared by reacting corresponding 4-pyridones wherein R represents 25 a hydrogen atom with a halogenating agent such as bromine, chlorine, sulfuryl bromide or sulfuryl chloride. This reaction is usually carried out in a suitably inert solvent such as ethylene chloride or methanol and at a temperature of 0-100 ° C.

Preparative illustrative compounds of formula I are set forth in Table I below, which also contains melting points and elemental analyzes. The exemplary embodiments listed in Table I show the preparation of some of the compounds in Table I. In these examples, all temperatures are in ° C and parts and percentages by weight, unless otherwise stated.

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7

TABLE I

9H3 5 | O CH CH δ 10 Elemental analysis (calculated

Connection values at the top, found value see below) _

No. X_Y R Mp._C Η N X

1 1 4-C1 H 358-9 60.55 4.36 5.06 12.77 60.85 4.42 4.99 13.07 2 4-C1 H Na> 300 56.10 3.70 4, 67 11.83 55.29 3.78 4.73 11.65 3 H HH 250-1 69.12 5.39 5.76 - 20 69.57 5.40 5.61 - 4 Η H Na> 300 63 , 39 4.56 5.28 - 61.54 4.78 5.18 - 5 4-CH3 Η H 238-40 70.02 5.88 5.45 - 70.14 6.02 5.29 - 25 6 4-CH 3 H Na> 300 64.51 5.05 5.02 - 63.45 5.18 5.09 - 7 3,4-diCl Η H 276-7 53.87 3.55 4.49 22.72 54.02 3.54 4.32 22.68 8 3,4-diCl H Na 296-7 50.32 3.02 4.19 21.22 30 45.25 3.17 4.05 21.40 9 4-F HH 260-1 64.36 4.63 5.36 7.27 63.89 4.59 5.53 7.07 10 4-FH Na> 300 59.36 3.92 4.95 6.71 58.83 3.88 5.03 4.95 35 11 3-C1 Η H 254-5 60.55 4.36 5.04 12.77 60.03 4.31 5.05 13.63

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δ TABLE I (continued)

Elemental analysis (calculated compound values at the top, found values see below) _

No. X_Y R Mp._C Η N X

12 3-C1 H Na> 300 56.10 3.70 4.67 11.83 53.57 3.75 4.46 11.45 10 13 4-CH3,3-Cl Η H 247-51 61.75 4 84 4.80 12.16 61.61 4.88 5.27 12.24 14 4-CH3,3-Cl H Na> 300 54.29 4.56 4.22 10.66 54.88 4.23 4.39 11.05 15 4-0CH3 Η H 219-21 65.92 5.53 5.13 - 15 65.52 5.39 5.18 - 16 4-0CH3 H Na 295-8 - 17 4-CF3 Η H 230-2 57.88 3.89 4.50 18.31 58.31 3.93 4.66 18.04 18 4-CF3 H Na> 300 ....

20 19 4-Br Η H 244-6 52.19 3.76 4.35 24.81 52.67 3.85 4.60 24.84 20 4-Br H Na> 300 - 21 4-C1 naph- Η H 264-6 65.96 4.31 4.27 10.82 thyl 65.68 4.27 4.41 11.03 25 22 4-C1 naph- H Na> 300 - thyl 23 4-C1 Br H 243- 6 47.14 3.11 3.93 - 47.65 3.13 4.29 - 24 4-C1 Br Na> 220 - 30 25 4-Br Br H 248-50 41.92 2.77 3.49 39 , 85 42.06 2.72 3.91 40.33 26 4-Br Br Na 290 - 35

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9 TABLE I (continued)

Elemental analysis (calculated compound values at the top, found values see below) _

No. X_Y R Mp._C_H_N_X

27 4-Br H CgHg 129-30 54.87 4.61 4.00 22.82 54.97 4.69 3.98 23.33 10

H

YVVC02E

XX

15

X

20 28 4-C1 Η H 271-73 59.21 3.82 5.31 13.45 59.17 3.76 5.71 13.49

Example 1 Preparation of N- (4-chlorophenyl) -5-carboxy-4,6-dimethylpyrid-2-one (Compound 1, Table I) - (a) 4-Chloroaniline (48.4 g), p-toluenesulfonic acid (4.7 g) and ethyl isodehydracetate (65 g) are suspended in cumene (260 ml). The reaction mixture is refluxed and water is collected in a Dean-Stark trap.

After 18 hours, the reaction mixture is cooled and washed with dilute hydrochloric acid to remove excess 4-chloroaniline. The cumen is then removed in vacuo leaving the crude 5-carbethoxy-N- (4-chlorophenyl) -4,6-dimethylpyrid-2-one as a dark brown oil.

(b) The crude ester prepared under (a) above is suspended in a solution prepared by mixing methanol (500 ml), water (500 ml) and 50% aqueous sodium hydroxide (50 g). The suspension is refluxed for 6 hours. The solvent is then removed in vacuo and replaced with water (1000 ml). Insoluble material is filtered and discarded. The clear,

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The aqueous layers are then acidified with hydrochloric acid and the resulting precipitate is filtered off and dried to give (after recrystallization from acetone) 55 g of product, N- (4-chlorophenyl) -4,6-dimethylpyrid-2-one-5-carboxylic acid , with a melting point of 258-9 ° (dec.).

5

Example 2

Preparation of N- (4-bromophenyl) -5-carboxy-4,6-dimethylpyrid-2-one (Compound 19, Table I)

Ethyl hydrate acetate (20 g, 0.102 mol) and 4-bromaniline (19.3 g, 0.112 10 mol) are dissolved in 50% aqueous acetic acid (100 ml). The mixture is refluxed for 12 hours, the solvent is removed and the crude ester is isolated as a brownish oil.

The crude ester isolated above is heated for 6 hours with 300 g of 5% NaOH in 1: 1 methanol / water. The mixture is cooled, diluted with water (100 ml) and filtered to remove insoluble material. Part of the methanol is removed in vacuo and an additional portion of water is added. The clear basic solution is then acidified and the resulting precipitate is filtered off and dried. Recrystallization from acetonitrile affords pure N- (4-bromo-phenyl) -5-carboxy-4,6-dimethylpyrid-2-one (5.3 g, 16.1% yield) with a melting point of 244-6 ° ( dec.).

Example 3

Preparation of N- (4-bromophenyl) -3-bromo-5-carboxy-4,6-dimethylpyrid-2-one (Compound 25, Table I) Sodium N- (4-bromophenyl) -4,6-dimethylpyride Dissolve -2-one-5-carboxylate (285 g 0.00828 mole) in dry methanol (50 ml). Bromine (1.59 g, 0.00994 mol, 1.2 equivalents) is dissolved in methanol (50 ml) and slowly added dropwise to the vigorously stirred saline solution over a period of 15 - 20 minutes. The solvent is then removed and the residue taken up in diluted base.

After free filtration of the insoluble material, the clear basic aqueous solution is acidified with hydrochloric acid. The resulting precipitate is filtered off and dried and recrystallized from acetonitrile to give N- (4-bromophenyl) -3-bromo-5-carboxy-4,6-dimethylpyrid-2-one 35 (2.25 g, 67; 8%) with a melting point of 248-250 °.

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11

Example 4

Preparation of N- (4-chlorophenyl) -5-carboxy-6-methylpyrid d-2-one (Compound 28, Table I) (a) Ethyl β-anilinocrotonate (23.9 g) is dissolved in dry benzene ( 200 ml) 5 and placed in a flask under a nitrogen atmosphere. Acryloyl chloride (10 g) is dissolved in additional dry benzene (200 ml) and added dropwise via a side-arm addition funnel over 1 1/2 hours. The reaction mixture is left at ca. 25 ° for 1 hour and then poured into water and extracted with methylene chloride. Evaporation of the solvent gives crude 5-carbethoxy-N-10 (4-chlorophenyl) -6-methyl-3,4-dihydropyrid-2-one (23.3 g), m.p. 124-6 ° (from hexane / ether ).

(b) The ester (15 g) prepared under (a) above is dissolved in chlorobenzene (500 ml). 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (23.2 g) is added and the mixture is refluxed for 3 hours. The reaction mixture is then cooled, filtered and diluted with an equal volume of methylene chloride and washed exhaustively with dilute aqueous sodium bicarbonate. The solvent is removed in vacuo and the crude product residue is recrystallized from hexane ether to give pure 5-carbethoxy-N- (4-chlorophenyl) -6-methylpyrid-2-one (8.3 g), mp 53-20 4 ° .

(c) The pyridone (7.0 g) prepared above (b) is suspended in 5% aqueous sodium hydroxide (200 ml). The mixture is heated on a steam bath for 1 hour, cooled and acidified with aqueous hydrochloric acid to give N- (4-chlorophenyl) -5-carboxy-6-methylpyrid-2-one (4.0 g), which is recrystallized from acetonitrile has a melting point of 271-3 ° with decomposition.

The compounds of formula I are particularly useful as chemical gametocides in cereal crops, such as wheat, barley, maize, rice, sorghum, millet, oats, rye and the like. Used as chemical gametocides, the compounds effectively induce a high degree of sterility in the treated plants without causing growth inhibition of significance in the treated plants. The compounds of formula I also produce other plant growth regulating reactions, such as e.g. in inhibition of seed formation in undesirable monocots for weed control, flowering regulation, fruiting and non-cereal seed inhibition regulation, maturation control and other related growth regulating responses.

The compounds of formula I, when used as plant growth regulators, are added in any amount which will be sufficient to

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12 to cause the desired plant reaction without causing any undesirable or phytotoxic reaction. Eg. the compounds, when used as chemical gametocides, are usually added to the plants to be treated in an amount of approx. 0.035 to approx. 22.4 kg / ha, and preferably approx.

0.14 to approx. 11.2 kg / ha. The amount supplied will vary depending on the plant species being treated, the compound used for the treatment and similar factors.

A preferred method of applying a compound of formula I as a plant growth regulator is by leaf feeding. When this method 10 is used, gametocid activity is most effectively produced when compounds are administered prior to meiosis and preferably after flower initiation. The compounds of formula I may also be applied in the form of a seed treatment by soaking the seeds in a liquid preparation containing the active compound or by coating the seeds with the compound. By seed treatment application, the compounds will usually be added in an amount of about 1/4 to approx. 10 kg per 112 kg of seeds. The compounds can also be applied to the soil or to rice crops the water surface.

The compounds of formula I can be used as plant growth regulators either individually or in admixture. For example, they can used in combination 20 with other plant growth regulators such as auxins, gibberellins, morphac- tines, ethylene-releasing agents such as ethephone, pyridones, cytokinins, maleic acid hydrazide, succinic 2,2-dimethylhydrazide, choline and its salts, (2-chloroethyl) - trimethylammonium chloride, triiodobenzoic acid, tributyl 2,4-dichlorobenzylphosphonium chloride d, polymeric N-vinyl 2-oxazoli di noner, tri (dimethylaminoethyl) phosphate and its salts and N-dimethylamino-1,2,3,6-tetrahydrophthalamic acid and its salts, 2,3-dichloro-butyric acid and its salts, and 3- (4-chlorophenyl) -6-methoxy-s-triazine-2,4- (1H, 3H) -dione.

Under certain conditions, the compounds of formula I can advantageously be used with other agricultural chemicals, such as herbicides, fungicides, insecticides and plant bactericides.

A compound of formula I may be added to the growth medium or plants to be treated, either on its own or as it usually occurs, as a component of a growth regulating composition or composition which also comprises an agronomically acceptable carrier. By "agronomically acceptable carrier" is meant any substance which can be used for dissolving, dispersing or dispersing a compound in the composition without impairing the effectiveness of the compound and which itself has no detrimental effect on the soil , the apparatus, the crops or that

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13 agronomic environment. Also, mixtures of compounds of formula I can be used in any of these compositions. The compositions may be of either solid or liquid composition or may be solutions. Eg. For example, the compounds may be formulated as wettable powders, emulsifiable concentrates, powders, granules, aerosols or light liquid emulsion concentrates. In such compositions, the compounds are stretched with a liquid or solid support and, if desired, suitable surfactants are incorporated.

Details of suitable compositions and other information relevant to the present invention can be found in Danish Patent Application No. 1060/78, corresponding to U.S.A. patent application no.

776,394 filed March 10, 1977.

The compounds of formula I may be applied as sprays by commonly used methods such as in the form of conventional hydraulic sprays, atomized sprays and powders. At low volume feeds, a solution of the compound is usually used. The dilution and feed volume will usually depend on such factors as the type of equipment used, the mode of application, the area to be treated, and the type and stage of development of the crop to be treated.

The data set forth in Table II below shows gametocide activity of typical compounds of formula I. These data were obtained by the following procedure.

One stack variety (Fielder) and one stack-free variety (Mayo-64) of spring wheat were planted in an amount of 6-8 seeds per day. 15.24 cm pot containing 25 a sterile medium of 3 parts by weight of soil and 1 part by weight of humus. The plants are grown under short-day conditions (9 hours) for the first 4 weeks to achieve good vegetative growth before flower initiation. The plants are then moved to long-term conditions (16 hours), which are produced by high-intensity light sources in the greenhouse. The plants are fertilized 2, 4 and 8 weeks 30 after planting with a water-soluble fertilizer (N 16%, P 25%, K 16%) in an amount of 1 teaspoon (about 5 ml) per day. 3.8 liters of water and is frequently sprayed with the insecticide sold under the trade mark "Isotox" for aphid control and powdered with sulfur for mildew control.

The compounds to be investigated are fed to the leaf growth of the 35-stacked female plants when these plants reach the flagship adsorption stage (stage 8 on Feekes' scale). All compounds are fed in a carrier volume of 468 l / ha containing a surfactant such as "Triton X-100" in an amount of 30 g / 100 l.

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After the axis of the marrow but before the anthesis, 4-6 axes per hour are enclosed. pot in a bag to prevent outcrossing. At the first sign of flower opening, two axes per cross-pollinated are crossed. pot with the stock-free male stem growth using the approximation method. As soon as the seeds become clearly visible, the shaft length is measured and small axes are counted in both enclosed and crossed axes. Male sterility can then be calculated as percent inhibition of seedling in the enclosed axis of treated plants. After full development, the seeds from crossed axes can be transplanted to determine the hybridization rate.

10 Percent sterility is calculated from the following formula:

Sc - St% sterility = -x 100

Sc 15

Sc = seed / small axis in enclosed axis on control plants.

St = seed / small axis in enclosed axis on treated plants.

Table II summarizes typical results obtained by examining 20 compounds of formula I. One means that no study was performed at the amount indicated.

Table II

25 ch3

T

Q <* s ^ NX (CH3 1 15

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TABLE II (continued) Quantity (lb / A) ~ _% sterility_ 5 X_ J_JL _8_ J_ _2_ J_ IZl 1/4 1/8 4-C1 Η H 100 100 100 96 4-C1 H Na 100 100 100 100 92 52 10 Η Η H 22 0 4 6 - Η H Na 46 0 13 8 - 4-CH3 Η H 21 0 0 14 13 12 2 4-CH3 H Na 0 0 0 14 11 2 3 3,4-diCl HH 98 93 80 12 20 16 12 15 3,4-diCl H Na 96 91 33 22 25 21 4 4-F Η H 0 0 0 9 0 24 13 4-FH Na 0 0 0 2 7 18 15 3-C1 HH 4000 3 3 2 3 - C1 H Na 0 2 0 - 20 4-CH3,3-Cl HH 64019 0 4- CH3,3-C1 H Na 0 2 1 0 1 6 - 4-OCH3 HH 56 18 2 9 4-0CH3 H Na 54 31 0 3 - 4-CF3 Η H 15 3 - 25 4-CF3 H Na 0 3 0 0 1 4-Br Η H 100 100 100 4-Br H Na 100 100 100 100 100 100 100 4-C1 naphthyl HH 2-- - 4-C1 naphthyl H Na 14 4 0 0 30 4-C1 Br H 9 7 9 16 13 4-Cl Br Na 15 13 13 20 13 - 4-Br Br H - - - - 4-Br Br Na 100 99 89 43 25 - 4-Br H C2H5 100 - 100 - 100 - 100 35

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16 TABLE II (continued)

VR

X

Quantity (1b / A) - _% sterility_ 15 X_ _Y__R__8__4 2 11/2 1/4 1/8 4-C1 Η H 100 88 49 19 4-C1 H Na 100 100 90 39 - 20 1 1b / A = 1 , 12 kg / ha.

Together! Igningsforsøg

Using the same procedure as described in Table II, the compound of Example 30 of U.S. Patent No. 25,761,240, i.e., the sodium salt of 1- (4-chlorophenyl) -3-carboxy-4,6-carboxylic acid, was tested. dimethylpyrid-2-one, on a typical grain plant, namely wheat with the following results: TABLE III 30

Dose% male gender% shaft length (kg / ha) sterility inhibition1 35 0.145 90 33 0.29 100 37 0.58 100 27 1.16 100 40

Claims (6)

1. Plant growth regulating 2-pyridones, in particular for inducing male sterility in plants of cereals, CHARACTERIZED in the fact that they have the general formula 35 r3 _4 I 2 XX! wherein R (Cj _) represents alkyl, represents carboxy (or an agronomically acceptable salt thereof) or carb (Cj_4) alkoxy, R3 represents hydrogen or (C · ^) alkyl, R ^ represents hydrogen, (Cj_4) alkyl or halogen, and R ^ represents phenyl substituted with 1 or 2 identical or different substituents selected from halogen, (C14)) alkyl, (Cj _) alkoxy and trifluoromethyl, or napthyl substituted with up to two identical or various halogen atoms. A compound according to claim 1, characterized in that 5 R represents phenyl substituted with 1 or 2 halogen atoms. 15 A compound according to claim 2 characterized in that R 1 represents methyl, 2 R represents carboxy or an alkali metal salt thereof, 3 R represents hydrogen or methyl, 4 20. represents hydrogen and 5 R represents phenyl substituted with chlorine or bromine. A compound according to claim 3 characterized in that c R represents 4-bromophenyl. 25 5. A process for regulating plant growth in a cereal plant CHARACTERISTICS by providing the growing plant, plant seeds or plant location with an effective amount of a compound according to any one of claims 1-4. 30 5 Hc where H = axis length of control plants, V and Ht = axis length of treated plants. 10 As can be seen from these results, far-reaching axis length inhibition occurs. By corresponding testing of compounds according to the invention, the following results are obtained (the figures in brackets are the corresponding results from Table III): TABLE IV Compound No. Dose% Male Gender% Shaft Length According to the Invention (kg / ha) Sterility Inhibition 2 0.58 92 (100) 3 (27) 20 1.16 100 (100) 0 (40) 20 0.145 90 ( 90) 3 (33) 0.29 99 (100) 5 (37) 0.58 100 (100) 10 (27) As can be seen from these results, the compounds of the invention provide good male sterility and virtually no shaft length inhibition. 30 6. A process according to claim 5, characterized in that the compound is applied to the growing plant prior to meiosis and in an amount effective to induce male sterility in the plant. 35