PLANT AND SEED TREATMENT METHOD AND COMPOSITION THEREFOR

Abstract: A method of treating plants and compositions for use in the method are provided and wherein the method is aimed at improving growth and/or flower and fruit retention and production and/or rendering a plant more susceptible to treatment by foliar sprays and/or for other purposes. The method utilises a treatment composition comprising either a tungsten compound, conveniently a tungstate, or a synergistic mixture of allopurinol and a molybdenum compound, conveniently a molybdate such as potassium molybdate.

Description: PLANT AND SEED TREATMENT METHOD AND COMPOSITION THEREFOR FIELD OF THE INVENTION This invention relates to a plant, propagule and seed treatment method whereby the growth of existing plants or plants resultant from germination of seeds or growth from other propagules can be regulated, at least to some extent, or alternatively such plants can be rendered more receptive to foliar applied agro-chemicals. It is to be understood that the term plant growth in this specification is used in its broadest context and includes such treatments as are aimed at earlier and more prolific flowering and at diminishing the occurrence of fertile flowers aborting prior to development of the relevant fruit. Similarly the term agro-chemical is used in o its broadest context and includes herbicides, insecticides, biocides, fungicides, plant growth regulators and fertilisers. The invention also relates to compositions particularly designed for use in a method according to the invention and also to certain pre-treated seeds and seeds obtained from treated plants, as well as other propagules originating from 5 plants treated with compositions according to the invention. BACKGROUND TO THE INVENTION It is believed that the endogenous plant growth regulator abscisic acid (hereinafter referred to as ABA) is largely responsible for the uptake and loss of water by the stomatal guard cells in plant foliage which, in turn, control the opening or closing of the stomates. o The production of ABA increases in plants which are subjected to stress whether the stress be caused by such factors as drought, cold, mineral deficiency or imbalance, excess soil alkalinity or acidity, disease or insect predation. In consequence of this agro-chemicals usually exhibit poor performance in plants which are subject to stress and the plants themselves naturally grow more slowly which has the effect of resulting in smaller, hardier, less productive plants which are less susceptible to stress factors such as agro-chemicals. Thus it has been shown that ABA can protect plants from the activity of several herbicides including the aryloxyphenoxypropionates as well as the cyclohexanediones. It still further appears that ABA production could be responsible for flowers, or the balance of ABA relative to other trees, aborting their flowers without developing into fruit. Still further, applicant believes that ABA generation could be responsible for shortening the lasting time of cut flowers and foliage and also the shelf life of fruit and vegetables. The relevant stress in this case may have been caused by the action of harvesting or cutting the flowers or fruit. OBJECT OF THE INVENTION It is an object of this invention to provide a method of treating plants, cuttings of plants, vegetative propagating organs such as tubers and seeds which is aimed at possibly limiting the amount of available ABA or changes the balance of ABA relative to other phytohormones in the plant etc, but, in any event, affecting the plant. It is another object of this invention to provide a composition particularly formulated for the purpose of carrying out these methods. SUMMARY OF THE INVENTION In accordance with this invention there is provided a method of treating plants in any form selected from the group consisting of established plants, plants being developed by propagation, and plants being developed by seed germination, the method comprising applying to the plant, or a plant habitat, an effective amount of a treatment composition selected from the group consisting of a compound containing tungsten, and a mixture of allopurinol (1H-Pyrazole [3,4-d] pyrimidin-4-ol) together with a suitable molybdenum compound. Further features of the invention provide for the treatment composition to be employed either simply as a plant growth regulating agent to provide the beneficial results apparently consequent on a diminished amount of ABA or a change in the balance of ABA relative to other phytohormones or, alternatively, for the treatment composition to be employed to enhance the receptiveness of plants to foliar applied agro-chemicals by increasing the opening of the plant stomates and increasing plant metabolic activity apparently following a reduction in, or a change of metabolism of, the endogenous ABA content of the plant. Initial investigation has indicated that the tungsten can be applied in many different forms such as, tungstic acid, H2WO4; sodium tungstate, Na2WO4; ammonium tungstate, (NH4)2WO_ι; tungsten suicide WSΪ2; or silicotungstic acid {H4[Si(W3θιo)4]26.H2θ)}. In the case of the mixture of allopurinol plus a molybdenum compound allopurinol is applied as such and molybdenum may be applied as potassium molybdate (K2 M0O4). The ratio between allopurinol and molybdenum in the mixture may be 1 :1 m/m although there is reason to believe that ratios of the two compounds may vary considerably and in particular from about 10:0 to 1 :10 or even more molybdate. The treatment composition may be applied on its own or together with another agrochemical as a composition in the form of a solution, emulsion or suspension, usually containing a surface wetting agent such as a surfactant, and may be applied directly to the plant foliage or, alternatively to the soil or other substrate in which the plants are grown. It is also within the scope of this invention to treat seeds with the treatment composition so that it will automatically be taken up by the plant upon germination with the consequential desirable effects thereof. Still further, seeds and other propagules formed on plants treated with the treatment composition may exhibit beneficial germination or growth characteristics. The invention still further provides seeds or vegetative propagules such as cuttings or tubers to which there has been applied a treatment composition according to the invention either directly or via a parent seed propagated during the formation of such seeds or other vegetative propagate. The application rate of the treatment composition to a plant will generally be determined by the method of application but in the case of foliar sprays, solutions containing from 0,1 microMoles/litre to 1 Mole/litre may all operate effectively depending upon the object to be achieved with effectiveness being optimal, as gauged at present, at about 0.25 to 1.0 milliMoles/litre at least in the absence of other functional ingredients. The application rate of the treatment composition will also depend on the method of application (e.g. foliar spray, injection, plant dip and soil drench). It is envisaged that the application of the invention may even result in the o extended shelf life of flowers and fruit, as indicated above, earlier flowering, as well as diminishing the self-abortion of fruit flowers, for example of avocado pear trees. It has also been shown that the inability to apply hormone type herbicides (eg 2.4-D and MCPA) together with aryloxphenoxypropionates ("FOPS") and the 5 cylcohexanediones ("DIMS") can be overcome by applying a treatment composition in accordance with this invention. BRIEF DESCRIPTION OF THE DRAWINGS In the following description reference will be made to the accompanying drawing which is a bar graph showing the effect of four compositions on the ABA and Xanthoxal contents of ripening avocado fruit. DETAILED DISCUSSION OF THE INVENTION In order to demonstrate the operation of the invention the following test results were initially obtained: 1. Results of an experiment to determine the optimum rate of tungsten to be added to Hoelon for wild oat control and to determine if the addition of ammonium sulphate would improve the effect of tungsten (Table 1). The wild oat biotype used in this experiment was a moderately resistant line from the United Kingdom. The tungsten was employed in the form of Sodium Tungstate in aqueous solution with standard surfactant addition. Table 1. Effect of tungsten and ammonium sulphate on the activity of 10 Hoelon on wild oats (UK biotype)*. Treatments Dry mass of surviving wild oat plants (9) 1. Control (no treatment) 4.1 2. Hoelon (2.5L/ha) 1.21 15 3. Hoelon (2.5L/ha) + 12mM (NH 4 ) 2 S0 2.17 4. Hoelon (2.5L/ha) + 0.1 OmM K2WO4 0.15 5. Hoelon (2.5L/ha) + 0.25mM K2WO4 0.11 6. Hoelon (2.5L/ha) + 0.50mM K2WO4 0.53 ., n 7. Hoelon (2.5L/ha) + 0.75mM K2WO4 0.21 Z 8. Hoelon (2.5L/ha) + 1.00mM K 2 WO 4 0.22 9. Hoelon (2.5L/ha) + 0.10mM K 2 W0 +15mM(NH 4 ) 2 SO4 1.56 10. Hoelon (2.5L/ha) + 0.25mM K 2 WO 4 + 15mM(NH 4 ) 2 SO4 1.60 11. Hoelon (2.5L/ha) + 0.50mM K2WO4 + 15mM(NH ) 2 SO4 1.64 12. Hoelon (2.5L/ha) + 0.75mM K 2 WO + 15mM(NH 4 ) 2 SO4 0.21 25 13. Hoelon (2.5L/ha) + 1.00mM K2WO4 +15mM(NH )2SO 4 0.03 Experiment conducted in acid washed sand Conclusion: Tungsten significantly improved the control of wild oats by Hoelon. The dosage rate response was very flat. The relatively high mass with 0.5mM tungsten was from one "curving-in" plant which was probably more resistant than the rest. Ammonium sulphate was antagonistic to the activity of Hoelon and negatively affected the effect of tungsten at the lower dosage rates. However, the best treatment was in fact tungsten at 1mM combined with 15mM ammonium sulphate. 2. Provisional results of an experiment to determine if a mixture of tungsten and allopurinol can overcome the antagonistic effect of MCPA on the control of wild oats by Hoelon. This experiment was conducted with a moderately susceptible ecotype of Avena fatua. The dosage rates of Hoelon was 1.25 L/ha and the tungsten and allopurinol 0.5mM. The o experiment was conducted in soil. Conclusion : This experiment clearly shows that tungsten can reduce the antagonistic effect of MCPA on the ability of Hoelon to control wild oats. 3. Provisional results of an experiment to determine if tungsten together with a mixture of allopurinol and molybdenum are synergistic or catalytic with 5 Hoelon and Topic in controlling an ecotype of Avena barbata which is resistant to both these products have shown that the three products (tungsten + allopurinol + molybdenum) are synergistic in the control of resistant Avena barbata by both Hoelon and Topic. Conclusion : Observations show clearly that the mixture of tungsten and 0 allopurinol plus molybdenum act synergistically to control wild oats that are otherwise resistant to the herbicides Hoelon and Topic. 4. Provisional results of an experiment to determine if the mixture of allopurinol plus molybdenum applied as a foliar spray can increase fruit set in avocados showed that there is a reduction in vegetative growth and a 5 concomitant increase in fruit retention in those inflorescence sprayed with the mixture. Conclusion : Mutual observations show clearly that the mixture of allopurinol plus molybdenum increase fruit retention in avocados. 5. An experiment was conducted to determine the effect of allopurinol, tungsten, molybdenum and the mixture of allopurinol plus molybdenum on the level of ABA and its precursor, mesocarp xanthoxal in avocado tissue (Fig. 1). Figure 1 shows the increase or decrease in the presence of mesocarp xanthoxal (black bars) and ABA (white bars) in ripening avocado fruit with different (increasing) concentrations of allopurinol, tungstate, molybdate, and the synergistic mixture of allopurinol plus molybdate. It will be noted that a decrease in ABA was only achieved with tungstate at the two lower concentrations of 0.75 and 1.5 and with the synergistic mixture allopurinol plus molybdate at all concentrations. The performance of pure allopurinol and molybdate can be regarded as comparative and furthermore indicative of the synergistic effect of the mixture of allopurinol and molybdate. Conclusion : This experiment proves that tungsten leads to a decrease in ABA content probably by preventing biosynthesis and that the mixture of allopurinol plus molybdenum also leads to a decrease in ABA synthesis probably by increasing breakdown of ABA to dihydrophaeseic acid (DPA) which has virtually no physiological method of modifying plant growth and can reasonably be expected to modify the effects of drought, heat, mineral (both deficiency and toxicity) and disease stress on plants. 6. Seed was produced from panicles excised from wild oats (A.fatua) by maintaining them in 100ml volumetric flasks containing 5% sucrose and various solutions of allopurinol and potassium molybdate. The flasks were kept on a laboratory bench at 20 degrees Centigrade and under natural daylight. The solutions were renewed every two days and at each renewal the tip of the peduncle was cut at an angle of 45 degrees, about 5mm from the base. Ripe seeds were harvested and stored at 4 degrees Centigrade until required for dormancy testing. Germination was tested by incubating three replicates of 25 seeds each per treatment and 15 degrees Centigrade in the dark with the seeds supported on filter paper wetted with distilled water or test solution. Germination was recorded daily over 10 days. The results are given in Table 2 below. Table 2 Treatment ABA PA DPA Germination ng g- 1 ng g 1 ng g- 1 % Control 437.2 105.5 401.1 0 Control I M 425.0 191.2 781.6 0 Control 10/<M 494.6 420.9 836.5 6.5 Control 10O&M ND* 43.9 103.2 13.0 Control IOOQΛM 105.3 82.1 358.5 2.6 # = Not detected The treatment composition was a one to one molar mixture of allopurinol and potassium molybdate and the concentrations are given in the table. Conclusion : This experiment showed that significant germination commenced at a concentration of 10 /M whilst the optimum was obtained at 100 tM. The percentage germination compares extremely well with zero percent of the control. 7. Tests were also conducted on wheat seed which was formed and germinated as described above except that the germination tests were carried out at 10 degrees Centigrade, 20 degrees Centigrade and 38 degrees Centigrade. The results are given in Table 3 below. The efficacy of the treatment composition according to the invention is clear at 10 degrees Centigrade and for high concentrations at 20 degrees Centigrade. Table 3 Treatment Germination Index Germination Temperatures 10°C 20°C 30°C 38°C Control 0.57 0.83 1.00 0.63 Control 10 M 0.81* 0.87 0.99 0.62 Control 50 rn 0.80* 0.88 1.00 0.62 Control 10O«M 0.77* 0.93* 1.00 0.62 Control 500 , 0.74* 0.85 0.99 0.68 Further tests have been conducted on a variety of plants and it has been found that the following effects can be achieved using the same type of treatment composition as indicated above. The effects achieved are as follows. Spraying avocado trees at a dosage rate of 0.5 to 1mM just after fertilisation of the flowers had taken place resulted in improved fruit retention compensated by a temporary inhibition of vegetative growth. Observation was visual and large scale trials have yet to take place. ii) A jointed cactus plant was was drenched with 0.5mM treatment composition and this resulted in the production of more than 20 flower buds, eight of which resulted in flowers and fruits. In the previous eight years only one plant had produced one flower. The relevant species was Opuntia aurantica. iii) When applied to calendulas as a foliar spray of 0.5mM a prostrate type of growth resulted with increased number of flowers produced much earlier than in the case of the controls. It appears that the treatment composition inhibits apical dominance which increased the number of flowers which originated as lateral buds. iv) Treatment of roses with the treatment composition resulted in a pom-pom type of flower with almost no stamens. It appeared that the antheas were converted into petals. A similar effect was achieved in fuschias. v) The treatment composition applied at 0.5mM at a rate of 20mm soil drench just before flower initiation in tomato plants lead to a substantial increase in flowering and fruiting. It is envisaged that the treatment compositions according to this invention may have considerably broad application and different effects depending upon the application rates and the particular species to which it is applied. It is even envisaged that suitable selected treatment compositions according to the invention may themselves exhibit fungicidal, antibiotic or herbicidal properties.

Claims: CLAIMS 1. A method of treating plants in any form selected from the group consisting of established plants, plants being developed by propagation, and plants being developed by seed germination, the method comprising applying to the plant, or a plant habitat, an effective amount of a treatment composition selected from the group consisting of a compound containing tungsten, and a mixture of allopurinol (1 H-Pyrazole [3,4-d] pyrimidin-4-ol) together with a suitable molybdenum compound. 2. A method as claimed in claim 1 in which the treatment composition o contains tungsten in a concentration of from 0,1 to 2,00 milliMoles/litre. 3. A method as claimed in claim 2 in which the said concentration is 0,25 to 0,5 milliMoles/litre. 4. A method as claimed in either of claims 2 or 3 in which the tungsten is applied as one or more of tungstic acid, H2WO4; sodium tungstate, 5 Na2WO4; ammonium tungstate, (NH4)2Wθ4; tungsten suicide WSi2; or silicotungstic acid {H4[Si(W3θιo)4]26.H2θ)}. 5. A method as claimed in claim 1 in which the treatment composition contains a mixture of allopurinol and a molybdenum compound. 6. A method as claimed in claim 5 in which the molybdenum compound is a 0 molybdate. 7. A method as claimed in either of claims 5 or 6 in which the molar ratio of allopurinol to molybdate ranges from about 10:1 to about 1 :10. 8. A method as claimed in any one of claims 5 to 7 in which the treatment solution contains from 0,1 tMoles/litre to 1 Mole/litre each of allopurinol 5 and molybdenum containing compound. 9. A method as claimed in any one of the preceding claims in which the treatment composition is applied as a foliar spray. 10. A method as claimed in any one of claims 1 to 8 in which the treatment composition is applied to the soil or other substrate in which a plant grows. 11. A treatment composition formulated for use in a method as claimed in any one of the claims 1 to 10 and containing a tungsten compound or a mixture of allopurinol and a molybdenum compound, or both. 12. A treatment composition as claimed in claim 11 and containing o additionally at least one other agrochemical. 13. A treatment composition as claimed in either of claims 11 or 12 in which the composition is adapted to be used as a foliar spray. 14. Seed and other propagules treated with a treatment composition according to any one of claims 11 to 13. 5 15. Seed and other propagules whenever formed as a product of a plant treated by a method as claimed in any one of claims 1 to 10.

Inventors: CAIRNS ANDREW LAWRENCE PATRICK, CAIRNS, ANDREW, LAWRENCE, PATRICK
Applicants: BRIGHTON BARRY DAVID, CAIRNS ANDREW LAWRENCE PATRICK, BRIGHTON, BARRY, DAVID, CAIRNS, ANDREW, LAWRENCE, PATRICK
Application year: 1998
Main classification: A01N59
IPC codes: A01N59