CS211385B2 - A method of sterilizing male anthers - Google Patents

Abstract

A method for selective sterilization of male anthers of plants, especially small-grain cereals, in which the plants are treated with a heterocyclic compound of the formula where R represents a hydrogen atom, an alkali metal or an alkaline earth metal, ammonium, an alkylammonium, the alkyl or alkyls of which contain at most 6 carbon atoms, or an alkyl with at most 10 carbon atoms, or with a composition containing this compound as an active ingredient. The plants are treated in the growth stage between late tillering and the appearance of the ear. Doses of 0.05 to 2.0 kg/ha are used for treatment. The mixtures used, if applicable, contain 50 to 1500 ppm of active ingredients.

Description

The invention relates to a method for sterilizing male anthers of plants, in particular cereal plants.

In order to obtain high-yielding hybrid seeds, breeders cross-pollinate the seeds of carefully selected parent plants, an operation which is time-consuming and requires highly specialized personnel, especially in the case of small-grain cereals, which have hermaphroditic flowers and are usually self-pollinating. Generally speaking, small-grain cereal hybrids can only be obtained if self-pollination is completely prevented, and in practice this is* achieved by manually removing the male anthers from the cereal flowers. Accordingly, if the flowers could be treated in such a way that the male anthers would be sterilized without affecting female fertility, this would represent a considerable advance in seed breeding.

A group of heterocyclic compounds has now been found that selectively sterilize male anthers when applied to plants, especially small-grain cereals.

The invention provides a method for sterilizing male anthers of plants, which consists in treating the plants with a heterocyclic compound of the general formula I,

Sr^cooR

AND

Η (I) in which

R represents hydrogen, alkali metal, alkaline earth metal, ammonium, alkylammonium, the alkyl group or groups of which preferably contain at most 6 carbon atoms, or alkyl of 10 carbon atoms, preferably up to 4 carbon atoms, in their growth stage between late tillering and ear emergence, either with a dose of the compound of the above-mentioned general formula I of 0.05 to 2.0 kg/ha, or with a preparation (mixture) containing 50 to 1500 ppm of the compound of the above-mentioned general formula I.

Where R represents a metal ion, it is preferably a sodium or potassium ion, but other metal ions may be used if desired.

The method according to the invention preferably treats small-grain cereals with a compound of the general formula: I, in which R represents hydrogen, an alkali metal, an alkaline earth metal, ammonium, an alkylammonium with an alkyl or alkyls with up to 6 carbon atoms, or an alkyl with up to 10 carbon atoms, preferably with up to 4 carbon atoms.

Cereal plants are treated in particular with 2-carboxy-3,4-methane-pyrrolidine or 2-methoxycarbonyl-3,4-methane-pyrrolidine.

Heterocyclic compounds can be applied to plants at various stages of their development, suitably during the period between the second tiller stage of the plant and just before ear emergence, i.e. during the period of plant stem growth. Application at this time results in essentially complete sterilization of the male anthers.

The compounds are preferably applied to small grain cereals such as wheat, barley, oats, rye, rice and millet, but can also be applied to large grain cereals such as maize and sorghum.

The compounds may be applied to plants as such, but, as is common practice in the application of chemicals to plants, it is preferred to apply the compound in the form of a mixture which includes, in addition to the compound, a carrier or a surfactant, or both a carrier and a surfactant.

It has also been found that when a heterocyclic compound of the general formula I is applied as a sterilizing agent, it can also cause suppression of the vegetative growth of the plants treated in this way. For example, a clear reduction in the elongation of the stems of wheat plants was observed after treatment of wheat plants with the compounds of the invention of the general formula I. This phenomenon was also observed in other cereals, as well as in legumes, such as linseed, mustard, sugar beet and soybean. It is clear that suppression of the vegetative growth of cereals at the right stage of their development can be very advantageous. For example, when cereals are exposed to different climatic conditions and changes, they become less sensitive to them.

Achieving sterilization of male anthers, as well as vegetative growth, by applying only one chemical compound can be very useful.

The dosage of the heterocyclic compound applied to plants to induce male sterility can vary over a wide range, but effective results in cereals have been obtained using doses ranging from 0.05 kg/ha to 2.00 kg/ha. Mixtures containing 50 to 1500 ppm of the heterocyclic compound are very suitable for this purpose. Growth suppression can be suitably achieved by applying doses ranging from 0.05 kg/ha to 8.00 kg/ha; successful results have been obtained with doses ranging from 0.1 kg/ha to 2 kg/ha.

The term "carrier" as used herein refers to a material, which may be of inorganic, organic, synthetic or natural origin, with which the active compound is mixed or converted into a form to facilitate application to the plant, seed, soil and other object to be treated, or for its storage, transportation or handling. The carrier may be in solid or liquid form. Any of the materials commonly used in the manufacture of herbicide application forms may be used as the carrier.

Suitable solid carriers are natural and synthetic clays and silicates, for example natural silicas, such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminum silicates, for example attapulgites and vermiculites; aluminum silicates, for example kaolinites, montmorillonites and micas; calcium carbonates, calcium sulfate; synthetic hydrated silicon oxides and synthetic calcium or aluminum silicates; elements, for example carbon and sulfur; natural and synthetic resins, such as coumarone resins, polyvinyl chloride and styrene polymers with copolymers; solid polychlorinated phenols; bitumens, waxes, for example beeswax, paraffin wax and chlorinated mineral waxes; and solid fertilizers, for example superphosphates.

Examples of suitable liquid carriers are water, alcohols, for example isopropyl alcohol, glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers, aromatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosene, light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene, trichloroethane, including liquefied gaseous compounds. Mixtures of different liquids are often suitable.

The surfactant may be an emulsifier, dispersant or wetting agent; it may be nonionic; or ionic in nature. Any of the surfactants commonly used in the manufacture of herbicide or insecticide application forms may be used. Examples of suitable surfactants are sodium or calcium salts of polyacrylic acids and ligninsulfonic acids; condensation products of fatty acids or aliphatic amines or amides having at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; sulfates or sulfonates of these; condensation products, alkali metal or alkaline earth metal salts, preferably sodium salts, sulfuric or sulfonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulfate, sodium secondary alkyl sulfates, sodium salts of sulfonated castor oil and sodium alkylarylsulfonates, such as sodium dodecylbenzenesulfonate and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention can be formulated as wettable powders, dusts, granules, solutions, emulsified concentrates and aerosols. Wettable powders typically contain 25, 50 or 70% by weight of the toxic component and typically also contain a solid carrier, 3 to 10% of a dispersing agent and optionally 0 to 10 _{% of} a stabilizer(s) and/or other additives such as penetrating agents and adhesives. Dusts are typically in the form of concentrates of similar composition to wettable powders but without a dispersing agent and are diluted in the field with another solid carrier to a composition containing typically 0.5 to 10% by weight of the toxic component. Granules are typically prepared in sizes of 10 and 100 BS mesh and can be produced by agglomeration or impregnation technology. Granules usually contain 0.5 to 25% by weight of the toxic component, 0 to 10% by weight of additives such as stabilizers, slow release regulators and binders. Emulsified concentrates usually contain in addition solvent ¹ and, if necessary, another solvent, 10 to 50% by weight of the toxic component, 2 to 20% by weight of emulsifiers and 0 to 20% by weight of appropriate additives such as stabilizers, penetration agents and corrosion inhibitors. Suspension concentrates are prepared to contain a stable, non-sedimenting flowable product and usually contain 10 to 75% by weight of the toxic component, 0 to 15% by weight of dispersants, 0.1 to 10% by weight of suspension-forming agents such as protective colloids and thixotropic agents, 0 to 10% by weight of suitable additives such as; defoamers, corrosion inhibitors, stabilizers, penetrants and adhesives and as a carrier water or an organic liquid in which the toxic substance is practically insoluble; some organic solids or inorganic salts may be dissolved in the carrier to prevent sedimentation or as agents to prevent water freezing.

The composition according to the invention may also contain other components, for example protective colloids, such as gelatin, glue, casein, gums, cellulose ethers and polyvinyl alcohol; thixotropic agents, for example bentonites, sodium polyphosphoric acid; stabilizers, such as ethylenediaminetetraacetic acid, urea, triphenyl phosphate, other herbicides or pesticides; binders, for example fixed oils.

Aqueous dispersions and emulsions, for example mixtures obtained by diluting a wettable powder or emulsified concentrate with water, are also within the scope of the present invention. Said emulsions may be of the water-in-oil or oil-in-water type and have a thick "mayonnaise" consistency.

The invention is further explained in the following examples, the terminology of which describing the growth stages during the development of cereal plants corresponds to "Plant Pathology", volume 3, 1954. Ex.

Tests were carried out with 2-methoxycarbonyl-3,4-methanepyrrolidine, referred to hereinafter as the sterilizing agent, on spring wheat plants of the variety "Calibri".

The sterilizing agent was applied at two stages of plant development, namely:

stage 7: second cob stage, i.e. just before the ear becomes recognizable as a separate organ;

Stage 10: mid-coil stage, i.e. the stage where the ear is formed and is visible as a bulge in the surrounding leaf sheath.

Groups of plants (20 pots, 3 plants per pot) at developmental stages 7 and 10 were sprayed with solutions of the sterilizing agent at 100 ppm or 500 ppm in water with the addition of a wetting agent (Triton C-155, concentration 0.1%). Control experiments were also carried out with plants treated with water and wetting agent alone. When an ear appears, a transparent bag is placed over the ear to prevent cross-pollination from untreated ears. The wheat plants are allowed to develop grains; the average number of wheat grains per ear is evaluated, the results of these evaluations are given in Table I.

Attempt number

Table I

Sterilizing agent concentration (ppm)

Average number of grains/ear after treatment of wheat plants at stage 7 and stage 10

Untreated control plants 1 2 3

— 36.3 36.3 0 34.3 32.8 100 3.4 0.5 500 0 0

From the experiments it can be seen that the sterilizing agent induces almost complete sterility at 100 ppm and perfect sterility at 500 ppm. Comparable results were observed in field trials.

In order to demonstrate that female fertility was not significantly impaired, male sterile plants were cross-pollinated with viable pollen. The seeds obtained from this cross-pollination were allowed to germinate and from the germination results it was determined that the seed was 100% viable.

Example 2

Tests with 2-carboxy-3,4-methanepyrrolidine were performed on wheat plants of the "Dove" variety.

The compound was applied to plants at 2 stages of plant development during the period of plant stem elongation before ear emergence, namely in:

stage 8: when the last leaf is just visible;

stage 9: when the tab (11gula) of the last leaf is just visible.

Groups of plants (20 pots, 3 plants per pot) at developmental stages 8 and 9 were sprayed with solutions of the compound at 72 ppm and 144 ppm in water and a wetting agent (Nonidet P-40; concentration 0.1%). Control trials were also conducted in which the plants were treated with water and wetting agent alone. When the ear appeared, a transparent bag was placed over the ears to prevent cross-pollination from untreated ears. The wheat plants were allowed to develop seeds; the average number of wheat grains per ear was evaluated; the results of this evaluation are shown in Table II below.

Attempt number

TABLE II

Sterilizing agent concentration (ppm)

Average number of grains per ear after treatment of wheat plants at stage 7 stage 10

Untreated control plants —

0

72

144

These results clearly demonstrate the sterility of male anthers, and in subsequent cross-pollination tests, female viability was confirmed to be intact.

Example 3

Tests were performed with 2-carboxy-3,4-me36.3 36.3

34.3 32.8

0

0 thanpyrrolidine on spring barley of the Imber variety.

The sterilizing agent was applied to plants at developmental stages 8 and 9 as described in the previous examples, except that the sterilizing agent was applied as a 100 and 200 ppm solution in water. The results are given in Table III below.

Attempt number

TABLE III

Sterilizing agent concentration (ppm)

Average number of grains per ear after treatment of wheat plants at stage 8 stage 9

Untreated control 1 2 — 21.2 21.2

100 0.25 16.25

200 0 7.95

The results clearly demonstrate the sterilizing effect of 2-carboxy-3,4-methane-pyrrolidine on barley.

Example 4

Tests were carried out with 2-carboxy-3,5-methanepyrrolidine on spring wheat of the Sappo variety.

Groups of plants (10 pots and 2 plants per pot) at developmental stages 8 and 9/10 were sprayed with the sterilant as a 50 or 100 ppm solution in water with added wetting agent (Nonidet P-40; concentration 0.1%). Control tests were also performed by treating the plants with water or wetting agent alone. When the ear appeared, a transparent bag was placed on the ear to prevent cross-pollination with untreated plants. The wheat plants were allowed to develop seeds and the average number of wheat grains was scored; the results of these assessments are shown in Table IV below.

Attempt number

TABLE IV

Sterilizing agent concentration (ppm)

Average number of grains per ear after treatment of wheat plants at stage 8 stage 9/10

Untreated control plants 1 2

100

41.6

4.1

0.1

41.6

38.9

22.1

Example 5

Before harvesting the ears of wheat plants used in the experiment in Example 1, the height of randomly selected main stems of wheat plants treated at stage 7 was compared with the height of 10 control stems of untreated plants by measuring the distance between the ear node and the base of the ear. The results are given in the following Table V.

TABLE V

Sterilizing agent concentration Average stem length (cm.) Length reduction in % (ppm)

Check 50 33.4 26.0 22.0 100 25.4 24.0 200 23.8 28.7

The results clearly show that the stem length of wheat plants treated with 2-methoxycarbonyl-3,4-methanopyrrolidine is noticeably reduced compared to untreated plants.

Example 6

Vegetative growth suppression was also observed when larger quantities of cereal and non-cereal plants were treated with 2-carboxy-3,4-methane-pyrrolidine at a dose of 0.2 and 1 kg/ha, respectively. Vegetative growth suppression was assessed visually on a scale of 0 to 8, with 0 indicating no growth suppression and 8 indicating significant growth suppression without killing the plants. The results of the foliar spray applications are given in the following Table VI.

TABLE VI

Corn rate (kg/ha)

Rice Hedgehog Oats Leather Leg

Flax Mustard Diabetes Soybean seed

15 5

0.2 0 2 2

5 7 8

3 5 8

Example 7 with boxy-3,4-methane-pyrrolidine (treated after

10 plants), as the following table shows- Effect on suppressing the growth of perennial ryegrass bulk VII. was evaluated using foliar sprays of 2-car- TABLE VII Rate (kg/ha) Root growth Height (cm) Fresh matter (gj 0 check 18 31 14 0.5 15 30 15 2.0 20 23 12 5.0 17 19 10 The results clearly demonstrate clear suppression- Example 8 low altitude and no adverse effect on the cutting, which is useful in influencing Experiments similar to those were conducted the growth of grass. described in example 7 with soybeans of the variety "Amsoy, formerly before the flowers appeared. After- the dose used and the stem heights determined are given in the following table VIII. TABLE VIII Dose Height (cm) after spraying (weeks) Height increase (cm) (kg/ha) 1 2 3 for the test period 0 (check) 51 87 90 54 0.5 39 39 39 2 1.0 36 36 37 3 Recurrence was observed clear reduction the heights of plant stems. During the test- period not observed flowering. OBJECT INVENTION

1. Method of sterilizing male anthers in

Claims (3)

A method for sterilizing male anthers in plants, characterized in that the plants are treated with a heterocyclic compound of formula I, wherein: R stands for hydrogen, alkali metal, alkaline earth metal, ammonium, alkylammonium, whose alkyl or alkyl alkyls contain no more than 6 carbon atoms, or alkyls of no more than 10 carbon atoms, in their growth stage between late offshoot and spike, either dose of a compound of the above formula I 0.05 to 2.0 kg / ha, or mixtures containing 50 to 1500 ppm of a compound of the above formula I. 2. A process according to claim 1, wherein the small grain cereal is treated with a compound of formula (I) wherein R is hydrogen, an alkali metal, an alkaline earth metal, ammonium, alkyl ammonium of alkyl or alkyl having at most 6 carbon atoms, or 10 carbon atoms, preferably up to 4 carbon atoms. 3. A process according to claim 1, wherein the cereal plants are treated with 2-carboxy-3,4-methano-pyrrolidine or 2-methoxycarbonyl-3,4-methano-pyrrolidine.