GB2448593A - Method of controlling bud burst - Google Patents

Abstract

Methods of controlling of bud burst in plants using carbohydrates. The methods involve both the delay of bud burst in a plant or promotion of bud burst comprising the use of a carbohydrate selected from a sugar and a sugar alcohol and combinations thereof. The sugar or sugar alcohol can be applied directly to the buds of a plant and repeated applications can be made. Whole or part crops can be treated. The preferred sugar is trehalose and the preferred sugar alcohol is sorbitol. An applicator having a nozzle for applying the carbohydrate in solution is claimed.

Description

1 2448593

CONTROL OF BUD BURST IN PLANTS

The present disclosure relates to the control of budburst in plants. Included in the present invention are methods and apparatus for controlling budburst, methods of producing plants and plant material and compositions for controlling budburst as well as other subject matter.

BACKGROUND

The rate of global warming since 1976 has been greater than at anytime in at last the past 100 years (IPCC, 2001 Climate change 2001. Third assessment report of Intergovernmental Panel on Climate Change") and ongoing changes in temperature have already contributed to a precocious 16 day shift in bud flushing for Mediterranean deciduous trees as compared to 50 years ago (Penuelas and Filella, 2001 Science 294(5543): 793). Surveys conducted in temperate European gardens also indicate that over the past 30 years leaf unfolding occurs 6 days earlier (Penuelas and Filella, 2001).

In contrast to past climatic changes, future changes are expected to occur at much faster rates, and extant forest tree populations will have to acclimate or adapt to the environmental modifications within a brief period of time.

Earlier bud burst may extend the growing season, but new leaves also become highly susceptible to freezing (Dormling, 1982, Silva Fenn. 16: 167-177). The timing of bud burst therefore determines the probability of spring frost damage, and the selection of genetic varieties with late bud burst is widely suggested as a tool to reduce the risk of spring frost damage for forest plantations (Hannerz, 1994 (Rep. No. 5)). Several studies concerning the effects of an increase in temperature depict an increased risk of spring frost injury if bud burst date is advanced (e.g. Murray et al., 1989, New Phytologist 113(3): 307-311). At present very little is known about the mechanisms that switch on' buds awakening them from their dormant phase.

The uncertainty of the timing of spring and the occurrence of late inclement weather causes significant losses of fruit, flowers and leaves in trees and shrubs, with newly developing tissues being prone to frost and cold damage. One of the prior art methods used to protect plants from such weather is physical protection by insulation; a practice too expensive and time consuming in the majority of circumstances. Other methods of controlling bud burst have been considered, but none have proved to be particularly satisfactory.

BRIEF SUMMARY OF THE DISCLOSURE

The invention relates to inter a/ia methods which control bud burst in plants. The methods of the present invention may be useful, for example, in that they allow growers to control the timing of bud burst to avoid poor climatic conditions e.g. frost, sleet and snow or to take advantage of forecasted good weather. Particularly, the invention relates to the use of certain carbohydrates to control (i.e. delay or accelerate) bud burst in plants.

The present invention is predicated on a finding that the timing of budburst may be modified (accelerated or delayed) by applying one or more selected carbohydrates to the plant, as described in more detail below. Thus, in one aspect of the present invention there is provided a method for controlling budburst in a plant, comprising causing a change in the content or distribution of soluble carbohydrate in the plant. In particular, in one embodiment, the soluble carbohydrate is for example a sugar or a sugar alcohol, or a combination thereof. The change may be effected directly by applying the soluble carbohydrate to the plant or, for example, by elevating the level of a precursor thereof in the plant. In any event, the invention, in this respect, lies in taking action to effect such a change and that the particular activities undertaken to achieve such action.

In one aspect of the present invention, there is provided a method of controlling bud burst in a plant comprising: applying a carbohydrate selected from a sugar and a sugar alcohol to the plant, or part thereof, when the plant is dormant.

In one aspect of the present invention, there is provided a method of cultivating a plant comprising applying a carbohydrate selected from a sugar and a sugar alcohol to the plant or part thereof prior to an expected bud burst.

In one embodiment, the method comprises applying the carbohydrate at a time before dehardening of the bud or buds of the plant has occurred. In an embodiment, the method comprises applying a first application of the carbohydrate from about 0 to 60 days before a time at which bud burst is expected to occur.

In one embodiment, the method is for delaying or retarding budburst in the plant, and comprises applying a sugar to the plant. In one embodiment, the sugar is selected from sucrose, maltose, raffinose and trehalose and combinations thereof. In one embodiment, the sugar is trehalose.

In one embodiment, the method is for stimulating budburst in the plant, wherein the method comprises applying a sugar alcohol to the plant. The sugar alcohol may be selected from sorbitol, isomers of sorbitol e.g. mannitol and galactitol, and combinations thereof. In one embodiment, the sugar alcohol is sorbitol.

The invention also relates to methods of staggering bud burst in an area of individual plants for example in an orchard and/or a forest. Thus, in a further aspect of the present invention, there is provided a method for staggering the bud burst within a single plant or within a crop of plants, which comprises selective application of the method to only portions of the total crop contemplated.

In one aspect of the present invention, there is provided a method of producing a plant product comprising carrying Out the method of controlling bud burst as described herein on a plant from which the plant product is to be harvested.

In one aspect of the present invention there is provided a plant product obtainable from the methods described herein.

In a further aspect of the present invention, there is provided a device for use in controlling bud burst in a plant which comprises a reservoir containing a carbohydrate selected from a sugar and a sugar alcohol in solution and at least one nozzle in liquid connection with the reservoir.

Also contemplated by the present invention is the use of a composition which comprises a carbohydrate selected from a sugar and a sugar alcohol to manipulate bud burst in a plant. In one embodiment, the composition may further comprise an agent which facilitates penetration of the plant e.g. the bud, by the sugar and/or the sugar alcohol. In one embodiment, the composition further comprises a wetting agent. Examples of suitable wetting agents include, for example, a surfactant. In one embodiment, the surf actant is a non-ionic surf actant e.g. Tween 20.

The present invention therefore aims to provide means for controlling or manipulating onset of bud burst in a plant. In one embodiment, the plant is a tree or shrub.

Embodiments of the present invention may be of relevance to the agricultural and forestry communities and provides new methods for regulation of bud burst. Methods and products of the present invention may be used to promote early vigour in a plant and more uniform bloom.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described by way of example only with reference to the following figures: Figure 1 is a graph detailing the forking and branching severity and spring frost (T C<0) for UK (diamond), Czech (triangle), German (square) and French (circle) provenances of Fraxinus excelsior at two field sites, Bangor (black symbols) (R2 = 0.97) and Oxford (open symbols) R2 = 0.94), where forking and branching severity is a summation of branching, forking and stem form all measured on a continuous scale from 0-15, wherein 0 is best and 15 is worst.

Figure 2 is a graph showing accumulated temperature above 10 C and flushing time for UK (diamond), Czech (triangle), German (square) and French (circle) provenances of Fraxinus excelsior at two field sites, Bangor (black symbols) R2= 0.99) and Oxford (open symbols) R2= 0.99) (Pearson's correlation: R2= 0.698 P0.05.) Figure 3 is a graph representing the effect of varying trehalose and sorbitol concentrations on bud burst where. = 100mM sorbitol, A = 5OmMol sorbitol, . = 20mM sorbitol and n lOmMol sorbitol, A = 5mMol sorbitol and a = 1 mMol sorbitol.

Figure 4 is a graph representing the effects of external application of trehalose and sorbitol and water on flushing time of Fraxinus excelsior in vivo, where A = sorbitol, A = control, o = trehalose (March application) and. = trehalose (February application).

Figure 5 represents the effect of external application of 0.1 M trehalose and sorbitol on flushing time in Fraxinus excelsior.

Figure 6 shows the effect of various sugar and sugar alcohols on bud burst.

Figure 7 is a graph representing accumulated temperature above 9.3CC against the day number at which bud swell occurs for Fraxinus excelsior.

Figure 8 is a graph showing the effect on tree architecture (comprising of forking severity, branching, stern form and height) of the timing of bud swell, where the lower the score, the higher the quality of timber produced.

Figure 9 is a graph showing the percentage of excised ash twigs with buds that burst during 40 days feeding.

Figure 10 is a photograph of experiments being carried out on twigs taken from apple, pear and plum. The twigs are being ted trehalose, sorbitol or water in a controlled environment cabinet at 15CC, supplied with 400pMol m2 s1 light during a 10 hour photo period.

Figure 11: Bud progress data from apple trees in the greenhouse. In this case, "bud burst" refers to the parting of bud scales allowing green tissue to be seen within, rather than blossom opening. The graph on the left shows the percentage of trees with at least one burst bud. The graph on the right shows the total number of buds burst on all trees of each treatment.

Figure 12: Example plot of air temperature outside and inside the greenhouse in which the experiments shown in Figure 11 are being carried out.

Figure 13: Example of photographic record of bud burst/leaf development; greenhouse raspberry. One branch per plant photographed once per week.

DETAILED DESCRIPTION

In one aspect. the present invention includes a method for controlling bud burst in plants comprising applying a carbohydrate selected from a sugar, a sugar alcohol and combinations thereof to the plant or part thereof when the plant is dormant. In one aspect of the present invention, there is provided a method of cultivating a plant comprising applying a carbohydrate selected from a sugar and a sugar alcohol to the plant or part thereof prior to an expected bud burst. As is shown herein, the methods of the present invention can be considered as methods of manipulating bud burst in plants.

In one embodiment, the method comprises applying the carbohydrate to a bud or plurality of buds of the plant. In one embodiment, the method comprises applying the carbohydrate at a time before dehardening of the bud or buds of the plant has occurred.

In one embodiment, the carbohydrate is applied before the waxy layer of the bud disappears. In an embodiment, the methods comprise applying a first application of the carbohydrate from about 0 to 60 days before a time at which bud burst is expected to occur. In an embodiment, the carbohydrate is applied as a solution. In one embodiment, the carbohydrate is applied as a solid or gel e.g. in the form of a powder.

In one embodiment, the method comprises applying a first application of the carbohydrate from about 10 to about 50 days before expected bud burst of the plant, optionally about 15 to about 45 days before expected bud burst of the plant, and optionally comprises applying a first application of the carbohydrate 20 to 40 days before expected bud burst.

In one embodiment, a first application of carbohydrate to the plant is on from about 25 to about 35 days before expected onset of bud burst, optionally 20 to 45 days, 15 to 30 days, 15 to 25 days before onset of bud burst.

In one embodiment, the method comprises applying more than one application of the carbohydrate(s) to the plant. In an embodiment, up to about twenty applications of the carbohydrate is applied to the plant at spaced apart intervals. The method may comprise repeating the application of the carbohydrate to the plant every 1 to 5 days, optionally approximately every 3 days. In one embodiment, the method comprises repeating the application of the carbohydrate until bud burst has occurred in the plant.

In one aspect of the present invention, there is provided a method of producing a plant product comprising carrying out the method of controlling bud burst in plant as defined herein, allowing the plant to develop and harvesting the plant product.

As used herein, the term "bud" refers to the protective structure which contains miniature leave, branches or flowers of a plant. The term "bud burst" (also referred to as "bud break" or "bud flush") relates to the opening of plant buds which signify the end of plant dormancy. In some embodiments, the term "bud burst" refers to the opening of buds on trees and other woody plants e.g. shrubs.

The present invention relates to the control of the process of bud burst either by delaying the onset of bud burst or by bringing forward the onset of bud burst as compared to the usual time for bud burst to occur.

Included in the present invention are methods which, at different times, both delay and bring forward budburst, e.g. in which action is first taken to delay budburst and later taken to bring it forward, or vice-versa.

The time at which bud burst occurs differs from species to species and between different locations where the same species is planted. The usual timing of bud burst is believed to be reliant on a number of conditions, not all of which have been identified. Factors which are considered to influence timing of bud burst include, for example, accumulated temperature. Accumulated temperature can be calculated as an accumulation of daily mean temperatures (T) above 5, 6, 7, 8, 9 and 10 C using the following equation (Diaz & Fernandez-Lopez 2005, Canadian Journal of Forest Research 35(2): 235-243): AT (accumulated temperature) = > (T-X) from 1st January to Bud Burst, wherein X is the temperature threshold being tested.

In one embodiment, the usual timing of the bud burst (i.e. the method of the present invention has not been carried out) occurs when the accumulated temperature is greater than about 4.5 C e.g. over about 5 C. The accumulated temperature at which bud burst may usually occur may be greater than 6 C, 7 C, 8 C or 9 C. In one embodiment, the accumulated temperature at which bud burst usually occurs may be about 9.3 C. The accumulated temperature may vary from species to species and between plants at different locations.

The terms "delay of bud burst" and "retardation of bud burst" each refer to delay of occurrence and/or onset of bud burst as compared to the occurrence of bud burst that would have occurred in that plant without performing a method of the invention. As described herein, a method of the present invention may include applying a carbohydrate as defined herein or modifying the physical amount of a metabolic precursor thereof. The expected bud burst timing may be determined for example by consulting historical records detailing the timing of bud bursts in previous years of the plant or plants at a particular site. An average date of bud burst occurrence can then be determined which can be used as a reference date for the initiation of the methods of the present invention. In one embodiment, the method may delay bud burst of a plant by up to three weeks (up to and including 21 days). In one embodiment, bud burst can be delayed for up to and including fourteen days, e.g. 2,3,4, 5, 6, 7, 8,9, 10, 11, 12, 13 or 14 days.

The terms "early bud burst," "promotion of bud burst" and "stimulation of bud burst" all refer to the bringing forward in time of the occurrence of bud burst in a plant when compared to the timing of bud burst occurrence that would have occurred in that plant without administration of a carbohydrate, e.g. a sugar alcohol, as defined herein.

Thus, a method of the present invention involves application of a carbohydrate to a plant. In one embodiment, carbohydrate is suitably applied in an amount which is effective to control bud burst.

In one embodiment, the method is for delaying bud burst e.g. to avoid a forecasted frost or cold period of weather. Suitably, the embodiment comprises taking an action to increase the physiological level of a sugar at a bud. In one embodiment in which the method is to delay bud burst, the method may comprise applying a sugar to the plant e.g. the buds of the plant. The sugar may be a disaccharide. In one embodiment, the sugar is selected from trehalose, sucrose, maltose, raffinose and combinations thereof.

In one embodiment, the sugar is applied in an amount sufficient to delay bud burst as compared to the usual timing of bud burst, which is described above. In one embodiment, the sugar is applied in quantities of from about 0.05m1 to about 3m1 per bud. In one embodiment, approximately 0.75ml to about 1.5m1 of sugar per bud per application is applied. In one embodiment, approximately 1 ml of sugar is applied to each bud per application. In one embodiment, the sugar is applied in a solution in a concentration of about 0.005M, 0.O1M, 0.015M, 0.02M, 0.025M, 0.03M, 0.035M, 0.04M, 0.045M, 0.05M, 0.055M, 0.06M, 0.065M, 0.07M. 0.075M, 0.08M, 0.085M, 0.09M, 0.1M, 0.15M, 0.2M, 0.25M, 0.3M, 0.35M, 0.4M, 0.45M or 0.5M.

In one embodiment, the sugar is trehalose. Trehalose is a non-toxic sugar cryoprotectant, which displaces bound water and protects cell membranes by hydrogen bonding to proteins and phospholipid polar ends more strongly than bound water (Rudolph et al 1986). It is considered to have an important role in stabilising membranes and proteins (Crowe et al, 1996, Biochimica Et Biophysica Acta-Biomembranes 1280(2); 187-196). It is also reported to be capable of modulating enzyme activity (Sola-penna, 1994a,b, Z. Naturforch 49C: 327-330; Naturforch 49C: 141-146.) Such modulation and protection of enzymes by trehalose may be explained by its ability to preferentially solubilise in the bulk water, being excluded from the solvation layer of proteins.

Benaroudj et al, ((2001) JBC 276(26): 24261 -24267)) found that trehalose protects cells and cellular proteins from damage by oxygen radicals. Without being bound by theory, it is suggested that trehalose may inhibit bud burst by regulating gene expression, deactivating' enzymes and binding free water in dormant buds, preventing damage by ice formation, until conditions are favourable in the spring. In one embodiment, the trehalose is extracted from yeast. In an alternative embodiment, the trehalose is obtained from starch e.g. cornstarch. Trehalose obtained from starch is commercialised by e.g. Hayashibara Shoji Inc., Okayama, Japan and Cargill.

In one embodiment, the method comprises increasing the physiological level of sugar at the bud, for example applying a sugar in addition to a sugar alcohol, wherein the ratio of sugar: sugar alcohol is such that the inhibitory effect of the sugar is dominant, thus delaying the bud burst. In one embodiment, the ratio of sugar: sugar alcohol is greater than 1:1 e.g. 1.2:1, 1.5:1 or 2:1.

In one embodiment, the method is for promotion of bud burst in a plant. The method may comprise acting to increase the physiological level of a sugar alcohol at a bud. In one embodiment, the method comprises applying a sugar alcohol to the plant e.g. to the buds or buds of a plant so as to promote bud burst. In one embodiment, the sugar alcohol is a monosaccharide and is selected from sorbitol, isomers of sorbitol and combinations thereof. In one embodiment, the sugar alcohol is suitably selected from sorbitol, galactitol, mannitol and combinations thereof. In one embodiment, the sugar alcohol is applied in a bud burst promoting amount. In one embodiment, the sugar alcohol is applied in quantities of from about 0.05m1 to about 3m1 per bud. In one embodiment, approximately O.75m1 to about 1.5ml of sugar alcohol per bud per application is applied. In one embodiment, approximately imI of sugar alcohol is applied to each bud per application. In one embodiment, the sugar alcohol is applied in a solution in a concentration of about 0.005M, 0.O1M, 0.015M, 0.02M, 0.025M, 0.03M, 0.035M, 0.04M, 0.045M, 0.05M, 0.055M, 0.06M, 0.065M, 0.07M. 0.075M, 0.08M, 0.085M, 0.09M, 0.1M, O.15M, 0.2M, 0.25M, 0.3M, 0.35M, 0.4M, 0.45M oro.5M.

In one embodiment, bud burst can be brought forward by up to three weeks. In one embodiment, bud burst can occur one to two weeks earlier e.g. 7, 8, 9, 10, 11, 12, 13 or 14 days early. In one embodiment, bud burst occurs less than one week early e.g. 1, 2, 3, 4, 5 or 6 days early.

In one embodiment, the sugar alcohol is sorbitol. Without being bound by theory, it is suggested that, in the context of the present invention, sorbitol and other sugar alcohols may be playing a role as an osmolyte at bud burst or regulating gene and enzyme activity, increasing the water content of buds, and aiding the rehydration of cells and activation of enzymes.

In one embodiment, the method comprises modulating the physiological content of both a sugar alcohol and a sugar at a bud, e.g. applying both a sugar alcohol and a sugar, in such a ratio that the stimulatory effect of the sugar alcohol is dominant. In one embodiment, the ratio of sugar alcohol: sugar is greater than 1:1 e.g. 1.2:1, 1.5:1 or 2:1.

Thus, the present invention encompasses methods which control bud burst in plants in which it would be advantageous to control and! or manipulate bud burst, whether by delaying onset of bud burst or by bringing forward onset of bud burst. In one embodiment, the method comprises application to the same plant of at least one sugar and at least one sugar alcohol, whether simultaneously or sequentially, optionally sequentially on different days, so as to manipulate the timing of bud burst in the plant.

Other methods involve application of either a sugar or sugar alcohol, to the exclusion of the other. Manipulation of the bud burst of a plant in this way may be useful in the case of, for example, unexpected changes in weather. For example, if the weather forecast shows that a period of good weather is likely, a quantity of sugar alcohol may be applied to the plant so as to promote bud burst. If the weather forecast changes unexpectedly so that a cold period of weather is forecast, a quantity of sugar may be applied to the plant e.g. the plant bud, in sufficient quantities to retard bud burst. This manipulation may be carried out up to when the buds burst or shortly before. Conversely, a sugar alcohol can be applied to the plant after a sugar has been applied in the event that good weather is forecast.

When both a sugar and a sugar alcohol are applied at the same time to the same plant, the effect on the bud burst of the plant will depend on a ratio of sugar: sugar alcohol. If the ratio of sugar: sugar alcohol is above a transitional threshold, delay of the bud burst will occur. Conversely, if the ratio of sugar: sugar alcohol is below a transitional threshold, promotion of early bud burst will occur. Transitional threshold levels may vary between different plants, plants at different locations and different species and can be determined empirically.

In one embodiment, the method is for controlling bud burst in a tree or shrub or plurality of trees or shrubs. The tree or shrub can be selected from, for example, fruit bearing trees, fruit bearing shrubs and trees species to be harvested for timber.

In one embodiment, the tree is selected from a deciduous tree and shrub. Deciduous trees and shrubs are typically trees and shrubs which lose their leaves for part of the year. In one embodiment, the plant is a tree which is destined for use in the timber industry. Examples of such trees include, but are not limited to, members of the ash family (Oleaceae family). In one embodiment, the plant is a tree from the Fraxinus genus. In one embodiment, the plant is a tree from the Fraxinus excelsior species. In one embodiment, the present invention may prevent bud burst in a member of Oleaceae family by up to 2 weeks so as to avoid damage caused by late spring frosts, wherein the method comprises the external application of a sugar e.g. trehalose, before bud dehardening.

Other examples of trees to which the invention may be applied include orchard trees and trees which bear fruit. In one embodiment, the invention relates to control of bud burst in deciduous trees. Examples of fruit bearing fruit to which the invention may be applied include for example, although in no way limited to, blueberry plants (Vaccirivim genus, sect. Gyanococcus), strawberry plants (Fragaria e.g. family Rosaceae), blackberry plants (Rubus genus, subgenus Eubatus), raspberry (Rubus, rubus idaeus), apple trees (Ma/us genus, for example sp. M. domestica), pear trees (Pyrus genus), fig trees (Ficus genus), peach trees and plum trees (both Prurius genus) and the numerous varieties and specie of fruit-bearing tree within each genus (e.g. P. domestica and P. spinosa within the Prunus genus). It will be clear to the skilled person that the invention is not limited to the list of trees above and other trees shrubs and flowering plants may be included in the present invention. In one embodiment, the plants are frost-resistant, i.e. can survive exposure to frost, particularly the plants may be deciduous plants which are frost-resistant when dormant.

Aspects of the present invention, therefore, reside inter a/ia in the regulation of bud dormancy by particular carbohydrates selected from a sugar and a sugar alcohol.

Particularly, the present specification shows that different carbohydrates may have opposing effects on dormancy. For example, in one embodiment of the invention, sugars, e.g. trehalose, can be used to maintain dormancy. In an alternative embodiment, sugar alcohols, e.g. sorbitol, can be used to promote bud burst. External misting of trees with dilute solutions of these sugars and! or sugar alcohols may be sufficient to allow the timing of budburst to be controlled, particularly in a period in springtime. In one embodiment, the method can be carried out in a two to four week period in springtime.

Thus, methods of the present invention may be used to avoid bud burst during late inclement weather (when forecasted) and! or utilise early warm weather. It is contemplated that the methods of the invention will be useful also for bringing forward the start of, or delaying the end of, a growing or fruiting season.

In those embodiments where carbohydrate is applied, the carbohydrate may be applied in any form which enables its effect on the bud burst to occur. In one embodiment, the carbohydrate is applied in a form which permits penetration of the plant e.g. the bud by the carbohydrate. The form of carbohydrate may also allow absorption of the carbohydrate by thebud. In one embodiment, the carbohydrate can be applied as an aqueous solution; in one embodiment, the method comprises making the solution. In one embodiment, the solution further comprises a wetting agent which facilitates the penetration of the plant e.g. the bud, by the carbohydrate. The wetting agent may be for example a surf actant e.g. Tween 20. Use of other wetting agents is envisaged by the present invention. In one embodiment, the solution comprises a wetting agent at a concentration of from about 0.005% to about 1% v!w e.g. 0.005, 0.01, 0.015, 0.02, 0.03, 0.04, 0.05, 0.075, 0.1, 0.5, 0.75 and 1% v/w. In one embodiment, the wetting agent e.g. Tween 20 is at a concentration of about 0.1% v/w.

In one embodiment, the method comprises applying the carbohydrate as a solid e.g. in powder or gel-like form.

In one embodiment, the method comprises applying the carbohydrate at a concentration of from about 1mM to about 110mM in aqueous solution, and optionally from about 10mM to about 100mM.

In one embodiment, the method comprises, prior to application of the carbohydrate, placing a dried form of the carbohydrate in solution. In one embodiment, the carbohydrate is mixed with water to form an aqueous carbohydrate solution e.g. a sugar solution and/or a sugar alcohol solution. In one embodiment, the solution may further comprise other agents e.g. insecticides, pesticides and fertilizers.

In one embodiment, there is applied to the plant a solution which consists essentially of the sugar or the sugar alcohol and water. In one embodiment, the solution may contain a sugar, a sugar alcohol and water. In one embodiment, the solution comprises trehalose and water. In one embodiment. the solution comprises sorbitol and water. In one embodiment, the solution further comprises a wetting agent. The wetting agent can be a surf actant e.g. Tween 20.

In one embodiment, the carbohydrate is applied as an aerosol. In one embodiment, the carbohydrate as defined above may be applied as a solid, e.g. a powder.

As stated above, the carbohydrate can be applied as a solution e.g. an aqueous solution. The concentration of the carbohydrate in solution can vary. For example, the carbohydrate concentration may be from about 1 mM to about 100mM. Thus, the carbohydrate may in a concentration of about 1mM, 5mM, 10mM, 15mM, 20mM, 25mM, 30mM, 40mM, 45mM, 50mM, 55mM, 60mM, 65mM, 70mM, 75mM, 80mM, 85mM, 90mM, 95mM or 100mM or greater.

For each plant to be sprayed, the concentration of the carbohydrate solution may vary between applications. For example, a lower concentration may be used in a first application and then a higher concentration may be used for a second or additional application. Alternatively, the reverse sequence is used. For example, although in no way limiting, a first application of the carbohydrate may comprise applying to the plant the carbohydrate in solution at a concentration of about 5OmMol. The method may then comprise a second application of the carbohydrate in solution ri a concentration of about lOOmMol.

Furthermore, the concentration of carbohydrate may depend on the plant variety or species. The concentration of carbohydrate applied may vary according to, for example, the timing of the application of the carbohydrate, the type of plant(s) to which the carbohydrate is to be sprayed and the location of the plant(s).

In one embodiment, the method of the invention may comprise a single application of the carbohydrate to the plant. In one embodiment, the method comprises repeated applications of the carbohydrate to the plant. For example, the carbohydrate may be applied to the plant on two, three, four, five, six, seven, eight, nine, ten, fifteen, twenty or more occasions to the same plant. In one embodiment, the method comprises repeated application of the carbohydrate until bud burst has occurred in the plant.

The first and subsequent applications may, for example, be spaced one day apart or longer. In one embodiment, the applications may be two days apart, three days apart or more. In one embodiment, the applications may be twenty hours apart, twenty five, thirty, thirty five hours, seventy hours, eighty hours, ninety hours or more.

In one embodiment, the carbohydrate solution may be mixed with other agents prior to application to the plant. For example, the carbohydrate solution may be mixed with e.g. insecticides, pesticides, anti-f ungal agents, bactericidal agents and fertilizers.

In an alternative to application as a solution or other liquid formulation, the carbohydrate may be applied as a solid, e.g. as a powder. In one embodiment, the carbohydrate may be applied as an aerosol. The carbohydrate may be mixed with agents, e.g. a fertilizer, an insecticide and a pesticide before being applied to the plant.

The carbohydrates used in the present invention may conveniently be transported and sold in packages. In one aspect of the present invention, there is provided a package for use in controlling bud burst in plants, wherein the package comprises a carbohydrate and instructions for using the kit to control bud burst in a plant. The package can comprise the carbohydrate in a powdered form and comprise instructions e.g. for reconstituting the carbohydrate into an aqueous solution. In one embodiment, the package further comprises a wetting agent. In one embodiment, the wetting agent is Tween 20. In one embodiment, the package comprises a sachet of wetting agent in liquid form. The package may comprise instructions for application of the carbohydrate to a plant. Alternatively, the package can comprise the carbohydrate in an aqueous solution. Optionally, the package may be sold as a kit comprising at least one of an applicator, a measuring device, or other suitable means for making, applying or diluting an aqueous carbohydrate solution to an appropriate final concentration.

In one aspect of the present invention, there is provided a device for use in controlling bud burst in a plant which comprises a reservoir containing a carbohydrate selected from a sugar and a sugar alcohol in solution and at least one nozzle in liquid connection with the reservoir.

The device may be a portable device which is suitably a hand held device. In this instance, the user may spray or mist each plant individually. The device may have a reservoir for storing the carbohydrate solution prior to and during application to the plant.

In one embodiment, the device may have a nozzle or plurality of nozzles for producing a spray of the carbohydrate solution and a conduit between the reservoir and the nozzle.

The nozzle may have at least one orifice for generating a spray of droplets of the carbohydrate solution. In use, the user directs the nozzle so as to provide a spray or plurality of sprays toward the plant. In one embodiment, the sprays are directed at a bud or plurality of buds on the plants. Application of the carbohydrate may be repeated once or more, optionally over a period of two to four weeks or longer.

In one embodiment, for example if a large number of plants are to be sprayed, the device may be mountable on a user's back. In this instance, the reservoir may be of a greater capacity (e.g. 5 litres, 10 litres, 15 litres, 20 litres or 25 litres). The device may comprise a nozzle which is attached to the reservoir via a hose. The hose can be flexible e.g. a hose formed from a flexible plastic or synthetic rubber. In one embodiment, the device may comprise a pump assembly activated with a trigger which is actuated to pump the carbohydrate solution from the reservoir to the nozzle. In one embodiment, the device may be automated so as to apply the carbohydrate solution to the plant at predetermined time intervals without intervention from a user.

In one embodiment, the device is in combination with a vehicle. Thus, in one embodiment, the method comprises applying the carbohydrate to the plant from a vehicle. In one embodiment, the vehicle can be an aircraft e.g. an aeroplane or helicopter.

In one aspect of the present invention, there is provided a plant obtainable from the methods of the present invention. In one aspect of the present invention, there is provided a plant, e.g. a tree, which experiences bud burst earlier as a result of having a sugar alcohol e.g. sorbitol applied to it, than a plant which has not had a sugar alcohol applied thereto. In one aspect of the present invention, there is provided a plant, e.g. a tree, which experiences bud burst later as a result of having a sugar e.g. trehalose applied to it, than a plant which has not had a sugar applied thereto. In one embodiment, a plant to which a sugar and/or a sugar alcohol is applied may comprise a residue e.g. a white powdered residue, on the treated part of the plant e.g. the bud. A plant to which sugar and/or sugar alcohol has not been applied typically does not have a residue thereon.

EXAMPLES

EXAMPLE 1

The effect of flushing time (bud burst) and late spring frosts was investigated for four provenances of F.exelsior (Ash) (German, Czech Republic, UK and French origin, Table 1) planted at two Forest Research field sites (Oxford, UK 1995 and Bangor, UK 1994).

At both sites, French trees always commence bud burst earliest in the spring, are most susceptible to spring frosts, and have the worst growth form, being severely forked. By contrast, German trees have the best architecture, being the tallest and straightest and commence bud burst last (3 weeks after the French trees). Czech trees flush second every year (H week after French trees), with poor form, and UK trees consistently flush third (2 weeks after French trees) having average form. Both field sites show that the forking of saplings increases with the frequency of frost events (Figure 1). The greater sensitivity at Bangor is correlated with the warmer earlier spring at this site.

The relationship between flushing date and temperature was quantified for the provenances in spring of 2006. The timing of flushing is known to be temperature dependent, above a threshold temperature. The threshold temperature was calculated by correlating the flushing date with accumulated temperatures above thresholds of 5, 6, 7, 8, 9 and 10 C. The only significant correlation (Pearson's correlation: R2= 0.698, P=0.05) between accumulated temperature and flushing for all provenances at both field sites is seen when 10 C is taken to be the threshold temperature (Figure 2). Different provenances appear to require different accumulated temperatures for the initiation of bud burst. At both sites French trees commence bud burst when an accumulated temperature above 10 C of H7.5 day degrees is reached. Czech trees require 20 day degrees for bud burst, UK trees -22 day degrees and German trees 26 day degrees.

The accumulated temperature required for the initiation of bud burst does not seem to be linked to the climate of origin (Table 1), for example one would expect Czech trees, having colder springs, to burst last and UK trees having milder springs to commence bud burst first. Daylight hours, latitude and longitude of provenance origin and flushing did not show a significant correlation. However, overwintering levels of trehalose were lowest in the French trees and highest in the German trees and there is a strong positive correlation between trehalose concentrations and flushing dates.

Average monthly temperature ( C) Provenance Sept Oct -Nov Dec Jan Feb Mar Apr [May Aver Lat( N) Long( E) age France 47.40 7.00 13.88 9.63 4.00 1.73 0.60 1.63 5.08 7.88 12.38 8.96 Czech 50.05 14.25 14.07 9. 13 2.81 --0.04 4.04 8.40 13.54 8.59 0.46 1.48 UK 53.48 -0.27 13.87 10.30 6. 72 4.42 3.62 4.26 6.07 7.96 10.97 9.54 Germany 49.51 8.30 15.46 10.47 5.27 2.46 1.58 2.41 6.63 10.10 14.66 10.4

HHHW

Table 1 Provenance origin and average monthly temperature from bud set to bud burst (From CRU IS 2.1, wwwcru.uea.acuk)

EXAMPLE 2

The effects of trehalose and effects of sorbitol on bud burst were investigated on excised twigs of F.exe/sior twigs. in vitro, 15cm excised twigs of F.excelsior were fed with different concentrations of sorbitol and trehalose and in different ratios from 1 mMol sorbitol and trehalose to 1 OOmMol in a growth cabinet at 15 C and 400umoL light.

Three weeks after the onset of the treatments, buds in water and sorbitol had all burst.

No buds on twigs in sorbitol plus trehalose had burst, and no twigs in trehalose had burst. Twigs initially treated in trehalose solution were then moved into either a sorbitol solution or water and these buds then proceeded to burst. The same experiments were then carried out using sugar solutions of varying trehalose and sorbitol ratio concentrations (Figure 3). When the trehalose is higher than the sorbitol, at any concentration, then more buds remain dormant then burst. Therefore the ratio of trehalose to sorbitol concentration controls the occurrence of bud burst.

EXAMPLE 3

The impacts of exogenous applications of trehalose and sorbitol were tested in the field (Western Park, Sheffield GA SK341 873), in vivo. In vivo, buds were sprayed with 0.1M solutions of sugars, with 1% v!w tween-20 solution, every 3 days. Spraying commenced in February and March for trehalose and February for sorbitol and the control. Trehalose application had two start dates (mid February and late March). The results repeated the observations shown in Example 2 that trehalose inhibits bud burst and sorbitol stimulates it. Furthermore the results showed that the timing of application is important, with a window of opportunity around mid-February, presumably before dehardening of buds occurs in early spring. Application of trehalose from mid February onwards delayed bud burst by 2 weeks and application of sorbitol promoted bud burst by -one week (Figure 3). No harmful effects of promoting or inhibiting bud burst by sugar spray application were seen as buds developed.

EXAMPLE 4

The effect on bud burst of a number of different sugars and sugar alcohols was tested by placing tree twigs n solutions comprising the sugars and sugar alcohols. The effects of the sugars and sugar alcohols are shown in Figure 4 and Table 2 below which show the percentage of bud burst on various dates.

Table 2

Treatment No. of Date Date Date Date Date Date (O.1M Twigs 25.02.07 13.03.07 15.03.07 19.03.07 20.03.07 22.03.07 unless stated otherwise) sorbitol 12 0 8.33333 33.33333 83.33333 100 100 trehalose 12 0 0 0 0 0 0 sucrose 12 0 0 16.66667 16.66667 16.66667 33.33333 raffinose 12 0 8.33333 8.33333 8.333333 8.33333 8.33333 mannose 12 0 8.33333 16.666667 33.333333 33.33333 33.33333 mannitol 12 0 0 41.66666667 75 75 75 maltose 12 0 0 16.666667 16.666667 16.66667 16.66667 Validamyc 12 0 8.33333333 16.666667 33.33333 33.33333 41.66667 in aiM 12 0 8.333333 8.333333 8.333333 8.333333 8.333333 trehalose: sorbitol Water 21 0 66.6666667 71.42857143 100 100 100 Treatment Date Date Date Date Date Date 23.03.07 26.03.07 29.03.07 02.04.07 05.04.07 10.04.07 sorbitol 100 100 100 100 100 100 Trehalose 0 0 0 0 0 0 Sucrose 33.3333 41.666667 50 66.666667 66. 666667 100 Raftinose 8.33333 8.3333333 8.3333333 33.333333 66.666667 100 Mannose 33.3333 41.66667 58.333333 66.666667 66.666667 100 Mannitot 75 75 83.3333333 91.666667 91.666667 100 maltose 16.6667 33.33333 41.6666667 75 75 100 Validamyc 50 58.33333 66.6666667 75 75 100 in 0.1 M T:S 8.33333 8.333333 8.3333333 16.666667 16.666667 33.3333 water 100 100 100 100 100 100 Example 5: Twig experiments to determine whether trehalose produced enzymically from cornstarch can inhibit bud burst to the same extent as trehalose purified from yeast.

Trehalose purified from yeast is expensive and so experiments are being carried out to determine whether trehalose obtained from cornstarch has a similar effect on inhibition of bud burst as that purified from yeast.

0.1 M trehalose from yeast and from cornstarch are applied to detached ash twigs when buds were still dormant. In addition, 0.1 M sorbitol from two different sources, SAFC and Aldrich, is also supplied to detached ash twigs. The experiments are carried out in a warm greenhouse (12CC -20 C). 15cm twigs are individually fed with lOmL of solution in a l5ml tube.

Results: As shown in Figure 9, both trehalose treatments produced similar results, suggesting that tretialose produced enzymically from corn starch can inhibit bud burst to the same extent as trehalose purified from yeast. Sorbitol from both sources has not yet had a noticeable effect on the acceleration of bud burst in this experiment. This was expected and believed to be due to the timing of the experiments which were too early for bud burst to occur, even if accelerated.

In the graph on the left of Figure 9, values are expressed as a percentage of the total number of twigs. In the graph on the right of Figure 9, values are expressed as a percentage of the twigs of which buds burst within the 40 days of the experiment i.e. buds that never burst are excluded.

Example 6. In addition to the experiment with ash, twig feeding experiments are being conducted with apple, pear arid plum. Twigs from two different varieties per fruit species were collected from a commercial orchard. Bud/blossom burst is being monitored in these twigs whilst they are fed with 0.1mM trehalose, sorbitol or water (see figure 10).

Results Thus far no differences between treatments have been observed for blueberry, strawberry, blackberry or raspberry plants. These species are now largely in leaf in the greenhouse, and blossom buds are just beginning to form. Date of blossoming will be monitored. Apples buds will be counted at two different stages: firstly, when green tissue is first visible emerging from the bud scales, and secondly, when blossom buds open. Data for green tissue emergence suggests that trehalose is having an effect (Figure 11).

Example 7

Inside and outside trials are also being carried out on apples, raspberries, blackcurrants, strawberries and blueberries. The trial is carried out in which spray treatments are applied to entire containerised plants three times a week. The trials are carried out on two sites, a greenhouse and an outside plot. Four treatments are used, 0.1 M trehalose, 0.1M sorbitol, water and a control in which plants were not sprayed at all. Deionised water is used for the spray solutions and 0.1% Tween is included to assist penetration of the treatment compounds into the buds.

Plant species used in the trail are; pear (conference), apple (cox, self-fertile), raspberry (glen ample), blackcurrant (ben connan), strawberry (darselect) and blueberry (nul).

Pear trees are not in the greenhouse. On both sites, there are ten replicate plants for each of the four treatments. Results are taken using photography (See Figure 13) and in the case of apple buds, the number of buds at each stage of development is recorded.

Claims (39)

1. A method of controlling bud burst in a plant comprising, applying a carbohydrate selected from a sugar and a sugar alcohol to the plant or part thereof when the plant is dormant.

2. A method of cultivating a plant comprising applying a carbohydrate selected from a sugar and a sugar alcohol to the plant or part thereof prior to an expected bud burst.

3. The method of claim 1 or claim 2, which comprises applying the carbohydrate at a time before dehardening of the bud or buds of the plant has occurred.

4. The method of any preceding claim, which comprises applying a first application of the carbohydrate from about 0 to about 60 days before a time at which bud burst is expected to occur.

5. The method of claim 4, which comprises applying a first application of the carbohydrate from 10 to 50 days before expected bud burst of the plant.

6. The method of claim 4 or claim 5, which comprises applying a first application of the carbohydrate 15 to 45 days before expected bud burst of the plant, and optionally comprises applying a first application of the carbohydrate 20 to 40 days before expected bud burst.

7. The method of any preceding claim, which comprises applying the carbohydrate to a bud or buds of the plant.

8. The method of any preceding claim, wherein the carbohydrate is applied as an aqueous solution, wherein optionally the method comprises making the solution.

9. The method of claim 8, wherein the aqueous solution further comprises a wetting agent.

10. The method of claim 8 or claim 9, which comprises applying the carbohydrate in a concentration of from about 1 mM to about 110mM, and optionally from about 10mM to about 100mM.

11. The method of any preceding claim, which is for delaying or retarding budburst in the plant, wherein the method comprises applying a sugar to the plant.

12. The method of claim 11, wherein the sugar is selected from sucrose, maltose, raffinose and trehalose and combinations thereof.

13. The method of claim 12, wherein the sugar is trehalose.

14. The method of any of claims 11 to 13, which comprises applying a sugar alcohol in addition to the sugar, wherein the ratio of sugar: sugar alcohol is such that the inhibitory effect of the sugar is dominant, thus delaying the bud burst.

15. The method of any of claims 1 to 10, which is for the stimulation of budburst in the plant, wherein the method comprises applying a sugar alcohol to the plant.

16. The method of claim 15, which comprises applying both a sugar alcohol and a sugar in such a ratio that the stimulatory effect of the sugar alcohol is dominant.

17. The method of claim 15 or claim 16, wherein the sugar alcohol is selected from sorbitol, isomers of sorbitol e.g. mannitol, galactitol and combinations thereof.

18. The method of claim 17, wherein the carbohydrate is sorbitol.

19. The method. of any preceding claim comprising applying more than one application of the carbohydrate(s) to the plant.

20. The method of claim 19, which comprises applying up to about twenty applications of the carbohydrate to the plant at spaced apart intervals.

21. The method of claim 19 or claim 20, comprising repeating the application of the carbohydrate to the plant every 1 to 5 days, optionally approximately every 3 days.

22. The method of claim 21, which comprises repeating application of the carbohydrate until bud burst has occurred in the plant.

23. The method of any preceding claim, wherein the plant is selected from a tree and a shrub.

24. The method of claim 23, wherein the tree or shrub is deciduous.

25. The method of claim 23 or claim 24, wherein the tree or shrub is selected from fruit bearing trees, fruit bearing shrubs and trees species to be harvested for timber.

26. The method of claim 25, wherein the tree is a member of the Oleaceae genus.

27. A method for staggering the bud burst within a single plant or within a crop of plants comprises selective application of the method described in any of claims 1 to 26 to only portions of the total crop contemplated.

28. A method of producing a plant product comprising carrying out the method of any of claims 1 to 26 on a plant from which the plant is to be harvested.

29. The method of claim 28 wherein the plant is a fruit bearing tree or shrub and the product is a fruit.

30. The method of claim 28, wherein the plant is a tree designated for use as timber, and the plant product is timber obtained from felling of said tree.

31. A plant product obtainable from the method of any of claims 28 to 30.

32. A device for use in controlling bud burst in a plant which comprises; a reservoir containing a carbohydrate selected from a sugar and a sugar alcohol in solution; at least one nozzle in liquid connection with the reservoir.

33. The device of claim 32, further comprising means for pumping the carbohydrate solution from the reservoir to the nozzle.

34. The device of claim 32 or claim 33, which is in combination with a vehicle.

35. Use of a composition comprising a carbohydrate selected from a sugar and a sugar alcohol to manipulate bud burst in a plant.

36. The use of claim 35, which is to retard bud burst in a plant, wherein the composition comprises a sugar selected from trehalose, maltose, sucrose and raffinose and combinations thereof.

37. The use of claim 35 or claim 36, which is to promote bud burst in a plant, wherein the composition comprises a sugar alcohol selected from sorbitol, isomers thereof and combinations thereof.

38. A method of reducing sapling forking in a tree comprising applying a carbohydrate selected from a sugar and a sugar alcohol to at least one bud on the tree prior to bud burst occurring in the tree.

39. The method of claim 38, which further comprises any one or more of the features disclosed in claims 3 to 26 or a permissible combination thereof.