Method for improving flowering of Rubiaceae plants

Abstract

The present invention relates to a method for shortening the time until flowering of plants and / or increasing the amount of flowers and / or fruits produced by plants of the Rubiaceae family. The method includes the steps of preparing a renewable plant seed or plant part, cultivating the plant seed or plant part until a cultivated shoot is obtained, wherein the cultivated shoot includes a branched part where an upright shoot and at least two inclined branches have developed, pruning at the branched part of the cultivated shoot by removing at least the upright shoot and leaving at least one inclined branch to obtain a pruned shoot, and cultivating the pruned shoot until flowers are formed on at least one inclined branch to obtain a flowering shoot.

Description

Technical Field

[0001] The present invention relates to a method for improving flowering, in particular for shortening the time to flowering of plants of the Rubiaceae family and / or increasing the number of flowers and / or fruits produced by plants of the Rubiaceae family, and to flowering plants obtained by said method.

[0002] [Background Art] Plants of the genus Coffea, also called coffee trees, are counted among the most valuable and widely traded commodity crops in the world. Under natural conditions, it takes 2 to 3 years after seed germination for a coffee tree to first produce flowers, and subsequent flower production occurs only about once a year. For breeders, it is necessary to go through this vegetative growth period so that controlled crosses can be made to obtain new genetic resources. Furthermore, agronomic evaluations are usually based on data collected from three subsequent crops of the same coffee tree. Therefore, overall, it takes about 5 to 6 years to complete one breeding cycle. In some cases, for example, in the case of inbred parental lines, several breeding cycles must be completed before obtaining offspring with satisfactory attributes.

[0003] To produce coffee seeds using controlled crosses, it is necessary to plant the parent plants in a seed garden and cultivate these plants for 2 to 3 years until flowers are formed. Pollen is manually collected from the parent plants and applied to the pistils of other plants serving as female plants.

[0004] The hybrid seeds produced by the seed garden require geographical or physical isolation from other coffee farms to ensure the genetic purity of the seeds obtained. Once planted, the trees in the seed garden remain planted in the same plot for several years, and the plot can supply a limited amount of coffee hybrid varieties. Furthermore, synchronization of the flowering events between parents is important to enable the acquisition of fruits and seeds. In some cases, synchronization does not occur under natural conditions, and thus crossing is hindered.

[0005] Considering the long breeding cycles of coffee trees and other plants in general of the Rubiaceae family, methods for promoting flowering have been proposed. These proposals require the treatment of plants with hormones and / or gene introduction.

[0006] European Patent Application Publication No. 0190885 (A2) describes treating woody angiosperms with gibberellins that can be rapidly metabolized to promote early flowering, and in some cases treating with the natural cytokinin zeatin to reduce the severity of biennial bearing.

[0007] International Publication No. 2004 / 010767 (A2) describes overexpressing PtM3 or PtM4 in the reproductive tissues of plants to promote flowering.

[0008] International Publication No. 2014 / 007400 (A1) describes introducing a recombinant geranyl pyrophosphate synthase large subunit protein (derived from goldfish) to produce plants that flower at an early stage.

[0009] However, these methods are limited by several drawbacks. Hormonal treatment of plants may have unpredictable side effects, thus impairing the reliability of breeding programs. Genetically modified plants face strict regulations and may be avoided by consumers and farmers. Furthermore, breeding genetically modified plants requires special precautions to comply with the containment official conditions, and many methods for introducing recombinant genes into plants require a lot of time and effort.

[0010] [Summary of the Invention] Against this background, the object underlying the present invention was to provide a reliable and easily implementable method for promoting flowering in plants and / or for increasing the number of flowers and / or fruits produced by said plants. Preferably, the method should not involve the use of hormones or introduced genes.

[0011] The present invention achieves this object by the features recited in the claims and further in the scope of this specification. In particular, the present invention provides a method for shortening the time to flowering of a plant and / or increasing the number of flowers and / or fruits produced by said plant, preferably at the first flowering of the plant, the plant being a plant of the Rubiaceae family. The method comprises a. providing a renewable plant seed or plant part; b. cultivating the plant seed or plant part until a cultivated shoot is obtained, the process including a fork with an upright shoot and at least one oblique branch having developed; c. pruning at the fork of the cultivated shoot by removing at least the upright shoot and leaving at least one oblique branch to obtain a pruned shoot; d. cultivating the pruned shoot until flowers are formed on the at least one oblique branch to obtain a flowered shoot; and includes.

[0012] The present invention also provides an advantageous use, in particular the use of a flowered plant obtained by being promoted according to the present invention for producing fruits and / or seeds or in a breeding program, and the use of pruning for advancing the flowering time of a plant of the Rubiaceae family and / or for increasing the number of flowers and / or fruits produced by said plant. In the method of the present invention, pruning is carried out on the cultivated shoot of the plant at the growth stage when the cultivated shoot has branched into an upright shoot and at least one oblique branch, and includes removing at least the upright shoot and leaving at least one oblique branch.

[0013] This method enables reliable induction of early flowering of Rubiaceae plants without performing genetic manipulation and without requiring hormonal treatment of the plants.

[0014] [Mode for Carrying Out the Invention] The method of the present invention is applicable to Rubiaceae plants in general. Rubiaceae is a family of angiosperms, commonly known as coffee, madder, or bedstraw. Economically important genera include Coffea (source of coffee), Cinchona (source of the anti-malarial alkaloid quinine), several dye plants (e.g., Rubia), and ornamental cultivars (e.g., Gardenia, Ixora, Pentas). Preferably, the Rubiaceae plant is a terrestrial woody plant, particularly characterized by opposite leaves with interpetiolar stipules and radially symmetric flowers. More preferably, the plant is a Coffea plant, including but not limited to Coffea arabica, Coffea benghalensis, Coffea canephora, Coffea liberica, Coffea racemosa, and any species derived therefrom.

[0015] In a preferred embodiment, the plant is a variant of Coffea arabica, particularly a variant showing male sterility. In this embodiment, the plant and method offer the advantage that crossbred progeny can be created more easily, in larger quantities, and more rapidly, for example, by crossing the flowers of pruned shoots according to the present invention with pollen from male donor plants, thereby avoiding unwanted self-pollination or unwanted cross-pollination. Crossbred plants created from pure-line Coffea arabica are on average more vigorous and robust than plants generated by self-pollination. The present invention enables increasing the number of flowers obtained, increasing the amount of beans, and creating more vigorous and robust plants. In one embodiment, the plant can be an allopolyploid variant.

[0016] The development of plants of the Rubiaceae family involves the elongation growth of their stems. When the stem reaches a specific length, a branching part is formed where the stem branches into an upright shoot and at least one inclined branch. With further development, especially when the original upright shoot of the plant is pruned, the inclined branch can form additional branching parts, and such branching parts can branch into additional branches and / or shoots. As used herein, the term "branching part" means the structure at the branch point of the stem formed during the elongation of at least one inclined branch.

[0017] Along the inclined branch, buds, which are undeveloped shoots, can be formed. Buds can be classified as vegetative buds, i.e., buds that develop into leaves, or floral buds, i.e., buds that develop into flowers. Buds are formed at the sprouting structure called a "node" of the inclined branch.

[0018] The method of the present invention and the plants obtained thereby can be used directly for producing fruits. However, special advantages can be obtained when the plants are used to promote the production of seeds and / or pollen in a breeding program. Therefore, when the plants are used in a breeding program, following the completion of the method, the produced pollen and / or pistils, and / or seeds can be used to propagate plants in a conventional manner, for example, using manual cross-breeding. In this regard, the advantage of the method of the present invention is that the number of floral buds per inclined branch, and more importantly, the number of pollinable flowers per inclined branch, preferably per plant, can be significantly increased.

[0019] Alternatively or in addition, for agricultural purposes or for phenotypic evaluation in the area of a breeding program, if plant fruits are desired, the plants can be further cultivated until the fruits develop, and after the completion of the method steps of the present invention, the fruits can be collected and further studied or processed. In this regard, the special advantage of the method of the present invention is that the number of fruits per plant that can be obtained after a short period of cultivation can be significantly and surely increased.

[0020] In the context of the present method, the term "plant" can refer to plant seeds or plant seedlings or plant parts that are capable of regeneration, i.e., capable of growth. The term "plant part" can in particular refer to rooted cuttings or cultivated shoots.

[0021] Generally, the method according to the invention starts with step a of providing a plant seed, seedling or plant part that is capable of regeneration. Preferably, the plant seed or plant part is provided in soil or hydroponics, or under other conditions that enable the cultivation of the plant seed or plant part in step b, for example, under soil-free conditions.

[0022] As used herein, "cultivation" means any conditions that enable the germination of plant seeds and the growth of the plant into a cultivated shoot, or the further growth of a plant part to produce a cultivated shoot. These conditions are well known to those skilled in the art of horticulture of Rubiaceae plants, particularly coffee. Plant seeds or plant parts are generally cultivated in horticulture, preferably not in the field or garden, but under more controlled conditions such as roofed and / or indoor, and / or within a greenhouse facility.

[0023] The general object of the method of the present invention is to shorten the time to flowering. Pruning in step c is extremely important in particular for inducing early flowering, but when the cultivation in step b and / or step d of the method of the present invention is carried out under optimal conditions, the object of accelerating the whole process is supported. In particular, such horticultural conditions should be selected to enable the rapid elongation of shoots and branches by optimized temperature, humidity, light, irrigation, CO2 concentration, and fertilization.

[0024] The cultivation in step b and / or step d of the method of the present invention generally involves growing under conditions beneficial to the plant. The cultivation may include growing at a temperature of 16 to 35 °C, preferably at least 18 °C, or at least 20 °C. Preferably, the temperature averages up to 32 °C, up to 30 °C, up to 28 °C, up to 26 °C, up to 25 °C, or up to 22 °C. In particular, in the research leading to the present invention, it has been revealed that the optimum temperature can vary depending on the plant species. For example, for plants of the Coffea arabica species, the temperature can be 16 to 28 °C; in the case of the Coffea canephora genus, the temperature can be 24 to 35 °C.

[0025] The cultivation in step b and / or step d of the method of the present invention can further include growing at a relative humidity (RH) of 60 to 95%, preferably at least 65% RH or at least 70% RH, and up to 90% RH, up to 85% RH, up to 80% RH, or up to 75% RH, for example 70 to 80% RH, for example 72% RH.

[0026] The cultivation in step b and / or step d of the method of the present invention usually includes irrigation, preferably providing fertigation, i.e., irrigation with a fertigation medium comprising or consisting of water with added fertilizer. The fertilizer is preferably water-soluble. The irrigation or fertigation can be carried out particularly advantageously by a sprinkler, by drip irrigation, or, for example, in a hydroponic system. The water or fertigation medium can be applied to the plants continuously or, for example, at intervals of once a day, preferably twice a day, or, for example, every about 8 hours, every 6 hours, every 4 hours, every 2 hours, every 1 hour, or every 30 minutes.

[0027] Preferably, the fertigation medium contains a fertilizer that contains all three essential nutrients, namely, an N-containing compound, a P-containing compound, and a K-containing compound. One skilled in the art can readily understand that the fertilizer can further contain additional nutrients such as Mg, S, Ca, etc., as well as micronutrients such as Cu, Mn, Ni, Zn, Fe, etc. The fertilizer can be in the form of, for example, powder or liquid. Preferably, the fertilizer contains 5 to 60% by weight of N, 5 to 60% by weight of P, and 5 to 60% by weight of K, where the percentages are understood as the weights of the elements N, P, and K as a proportion of the total weight of the fertilizer. Good results were achieved with a powdered fertilizer containing 20% by weight of N, 20% by weight of P, and 20% by weight of K in step b. During step d of the method of the present invention, the fertigation medium can contain, for example, a fertilizer containing more K, for example, 8 to 15% of N, 16 to 25% of P, and 28 to 40% of K. It has been found that a fertilizer with an increased amount of K can improve fruit formation in plants. Generally, the fertilizer can be contained in the fertigation medium at a concentration of 0.1 to 10 g / L. The fertigation medium can have a conductivity of 0.1 to 5 mS, preferably 0.2 to 2 mS, more preferably 0.5 to 1 mS, for example 0.8 mS.

[0028] Preferably, the cultivation in step b and / or step d of the method of the present invention is carried out in the form of vertical gardening and in a facility capable of vertical gardening. As used herein, "vertical gardening" means gardening in layers of vertically stacked cultivation containers, such as flower pots, and / or gardening under soilless growing conditions, for example using hydroponic techniques.

[0029] Optionally, during the cultivation in step b and / or step d of the method, the lighting is controlled. The light applied to the plants can include natural light and / or artificial light.

[0030] The artificial light useful in the method of the present invention is generally generated by a light source that emits light in the spectral range of 400 to 750 nm, for example, by a sodium lamp, preferably by an LED plant growth lamp that emits light having a wavelength corresponding to the absorption maximum of plant chlorophyll, particularly by one that emits a spectrum rich in the wavelengths of blue, red, and far red.

[0031] Preferably, the lighting during cultivation in step b and / or step d is, for example, by arranging the light source at an appropriate distance from the plant, for example, a maximum of 50 cm, preferably a maximum of 30 cm, or a maximum of 20 cm, for example, 2 to 50 cm or 2 to 40 cm, so that the plant receives natural light and / or artificial light having a photosynthetic photon flux density of 80 to 1500 μmol m -2 s -1 . In step d, this distance is preferably measured between the light source and at least one inclined branch. The cultivation in step d particularly preferably includes specifically stimulating the at least one inclined branch by exposure to a light source that illuminates the remaining at least one inclined branch. In contrast, the conventional horticultural method for coffee plants usually uses a light source arranged at a distance of 1 to 3 m from the inclined branches. This arrangement is due to, for example, conventional overhead light sources and / or the fact that upright shoots or further branching along the upright shoots block access to the inclined branches. This is because the research underlying the present invention has shown that during cultivation in step d, by directing particularly optimized lighting towards the inclined branches, the time to flowering can be further shortened and / or the number of flowers and / or fruits produced by the plant can be increased.

[0032] In a preferred embodiment, the lighting during cultivation is controlled by controlling the photoperiod, that is, the amount of time per day that the plant is exposed to light during cultivation in step b and / or step d. It is considered that the photoperiod plays an important role in determining the flowering time every year under outdoor natural growth conditions, and it has been found that by controlling the length of the photoperiod during cultivation step b and cultivation step d of the method of the present invention, the time to flowering of the Rubiaceae plants can be further shortened.

[0033] When the length of the photoperiod is controlled independently of each other or identically for each of steps b and d to be 8 to 14 hours per day, for example, 8 to 10 hours per day, 10 to 12 hours per day, 12 to 14 hours per day, 8 to 12 hours per day, or 10 to 14 hours per day, good results were achieved. In one embodiment, the length of the photoperiod during cultivation in step b is longer than the photoperiod during cultivation in step d. For example, in step b of the method of the present invention, it is 10 to 14 hours, and in step d, it is 8 to 12 hours.

[0034] In a further embodiment, the cultivation in step d may include changing the length of the photoperiod. Here, in the first period, the photoperiod can have a first length, and in the second period, it can have a second length different from the first length, for example, at least 2 hours different. For example, during the first period, the photoperiod can be 8 to 9 hours per day, and during the second period, the photoperiod can be 11 to 12 hours per day. The above first period and second period can each have a period of 1 to 5 months, particularly 2 to 4 months, for example, 3 months, independently of each other or identically. Here, the length of the photoperiod can be changed repeatedly, for example, periodically, for example, every 3 months, between the first period and the second period. It has been found that by changing the photoperiod in the second period of the cultivation in step d, earlier flowering of the plant can be induced.

[0035] In one embodiment, the light applied to the plant in step b and / or step d is only artificial light, and steps b and / or d completely or partially block natural light at all times or only during the time outside the photoperiod, that is, only while the artificial light source is turned off. For example, by covering the plant with a light-shielding housing or foil, or by implementing the method of the present invention under indoor conditions that effectively prevent the plant's exposure to natural light. This can be achieved, for example, by horticulture in a container or room with artificial lighting but no windows.

[0036] In an alternative embodiment, the light applied to the plant in step b and / or step d comprises only natural light or is only natural light. Also in this embodiment, lighting can be controlled by blocking natural light at times outside the photoperiod, for example, by covering the plant with a light-shielding housing or foil.

[0037] By controlling lighting, the method has the particular advantage that it can control more precisely, and in particular much more precisely than conventional methods, the induction of flowering in plants, i.e., the exact time at which flowers are formed.

[0038] A further advantage of the method according to the invention is that it enables the induction of flowering outside the natural flowering period in the field, and in the case of the coffee tree plant, flowering is related to the rainy season and / or the natural photoperiod. The advantage of being able to control the induction of flowering by the method according to the invention is that the induction of flowering can be synchronized between different plants. This is particularly advantageous in breeding applications as it enables easier propagation or crossing of plants.

[0039] Generally, the cultivation in step b is carried out until a stage is reached where a cultivated shoot is obtained which comprises a branching part from which an upright shoot and at least two oblique branches have developed. This growth stage corresponds to the first natural branching event and is thus well distinguishable for plants of the Rubiaceae family. For example, when grown from seeds, plants of the Rubiaceae family first grow into upright branches and then form a branching part from which one or two oblique branches grow outwards. In the natural environment, the upright shoot continues to grow and subsequently further oblique branches grow from new branching parts formed further above the upright shoot. In this way, the plant ultimately becomes a fully grown tree.

[0040] Generally, particularly from experience with the genus Cinchona, the time required for cultivation in step b, i.e., from the seed or shoot stage to the formation of the first two diagonal branches, is 2 to 6 months or 3 to 4 months of cultivation in step b. However, the cultivation period in step b will of course vary depending on the type and growth stage of the starting material prepared in step a, as well as the cultivation conditions selected in step b.

[0041] The cultivated shoots obtained in step b and pruned in step c generally contain a branching part, preferably exactly one branching part, from which an upright shoot and at least one diagonal branch have developed. In a preferred embodiment, the branching part used for pruning in step c is the first branching part that developed in the cultivated shoot during cultivation in step b. During the growth of Rubiaceae plants, particularly Cinchona plants, the first branching part develops one or two diagonal branches and one upright branch.

[0042] Pruning according to step c of the method involves cutting off the upright shoot and all diagonal branches except for at least one, preferably all diagonal branches except for exactly one. The cutting position varies depending on the size of the plant. In the case of Cinchona plants, good results were obtained when cutting was performed at a distance of up to 5 cm, preferably up to 2 cm, more preferably up to 1 cm, or up to 0.5 cm or 0.2 cm from the branching part. The cutting should not be too close to the branching part so as to damage the branching part itself. Such cutting can usually be achieved by keeping the cut at least 0.2 cm away from the branching part.

[0043] Generally, pruning according to step c of the method is carried out at the latest 1 month, preferably at the latest 3 weeks, at the latest 2 weeks, or at the latest 1 week after the branching part is formed, and even more preferably less than 1 week after the branching part is formed.

[0044] Optionally, the method further comprises, in step d, continuously removing any newly formed upright or lateral outgrowths from the pruned shoots, optionally involving the removal of leaves and / or vegetative buds formed on the inclined shoots. The research underlying the present invention has shown that the remaining inclined shoots develop at least one additional branching part after a specific cultivation period, and this branching part contains new upright shoots. By continuously pruning these additional shoots, the time to flowering can be further shortened and / or the number of flowers and / or fruits generated per inclined shoot can be further increased. The continuous removal can be carried out at least once every two months, preferably at least once a month, more preferably at least once every two weeks, or at least once a week to ensure optimal conditions.

[0045] An advantage of the present invention is that the time to flowering of the plant can be shortened without hormone treatment and / or genetic manipulation. Thus, in a preferred embodiment, the method does not include hormone treatment and / or genetic manipulation. Those skilled in the art will of course understand that, if desired, the method of the present invention can also include plants that have been hormone-treated and / or genetically manipulated, but this is not necessary for the method of the present invention to function.

[0046] The method of the present invention may involve, for example, applying drought stress to the plant during cultivation in step d. Drought stress can be induced, for example, by reducing the applied amount of the fertilized irrigation medium by at least 50%. The volume of the fertilized irrigation medium can be reduced until the first symptoms of drought stress in the plant, such as drooping, wilted leaves, loss of turgidity, etc., are observed. Drought stress can be applied to the plant, for example, over a period of 4 to 20 days. The inventors have found that applying drought stress as part of the present invention can further shorten the time to flowering. Furthermore, timely application of drought stress can be used to synchronize flowering among different plants.

[0047] Although not required, the method can include the step of applying at least one plant hormone to the plant during cultivation, and such plant hormone can be gibberellic acid, auxin, ethylene or any other plant hormone. The plant hormone can be applied to the plant continuously or at intervals ranging from once a week to once a year. For example, for gibberellic acid, a dose of 0.1 to 200 mg per application per tree has been proven useful. Preferably, at least one plant hormone is applied by contacting a fluid containing at least one plant hormone with the leaves of the plant, for example, by spraying a hormone-containing solution on the leaves of the plant.

[0048] The method according to the present invention has the advantage of enabling rapid flowering of plants. The time from completion of steps b to d of the method of the present invention, i.e., until flowering, can be 15 months or less, preferably 14 months or less, more preferably 13 months or less, 12 months or less, 11 months or less, or even 10 months or less. Therefore, the total time required from the Rubiaceae plant seeds or plant parts until flowers capable of propagating on the pruned shoots appear is considerably shortened compared to the flowering time required in nature. For example, the time required to obtain flowering (from b to d) is about 345 days for both the treated plants and the control plants.

[0049] A further advantage of the method according to the invention is that it is particularly suitable for vertical cultivation since it depends only or mainly on the elongation of one or more first inclined branches. According to one embodiment, the cultivation in step b and / or step d is carried out in a system in which the plants are arranged and cultivated in vertically stacked layers of cultivation containers, for example flower pots, and / or under soil-less growing conditions, for example using hydroponics technology. By pruning, it is necessary to cultivate only at least one branch that flowers and produces fruits and seeds according to the method of the invention. This is particularly effective since it requires less space and allows for the vertical arrangement of the cultivation containers. In contrast, unpruned plants of the same species occupy a much larger area, for example 3.5 times larger, and a larger volume, for example 8 times larger, than plants pruned according to the invention, and on average have fewer flowers per inclined branch after 11 to 15 months of cultivation.

[0050] Surprisingly, the method according to the invention not only results in promoted and better controlled flowering, but also in an increase in cultivation time and the number of flowers per plant mass. Furthermore, surprisingly, the method according to the invention has been found to enable more than one flowering event per plant over a period of one year. At present, it is considered that controlled lighting and / or continuous pruning are involved in this remarkable and very useful effect. Thus, the method according to the invention can optionally include at least a further step e following step d. The method according to the invention includes a step e of budding that takes place 250 days, preferably 220 days, after seed germination or from a cutting for further rooting, and the flowering shoots are cultivated for up to 8 months until flowers are formed again on the flowering shoots. Furthermore, it is preferred that the method according to the invention optionally includes a step e of budding that occurs 380 days, preferably 340 days, after sowing, following step d.

[0051] In particular, the cultivation in step e is carried out until new flowers are formed on the inclined branches. Regarding cultivation, all that has been described for steps b and d equally applies to step e. Using the method of the present invention, the period of step e, i.e., the time between the end of the first flowering in the inclined branches and the second flowering, can be shortened to a period of at most 8 months, preferably at most 6 months, or at most 4 months. Further cultivation in step e can be carried out using, for example, controlled lighting as in step d, and / or further continuous pruning with natural light completely or partially blocked. Good results were obtained by horticulture in a greenhouse at 16 - 35°C, 60 - 95% RH, and fertilizing irrigation.

[0052] Due to the special pruning during cultivation and the very early flowering, the flowering plants obtained by the method of the present invention differ greatly in many respects from the plants of the Rubiaceae family at the flowering stage known in the prior art. The plants obtained by the method of the present invention not only differ in appearance from leaving only or mainly one or more inclined branches pruned. The plants of the present invention also flower at a much younger age compared to the flowering plants of the Rubiaceae family at the flowering stage known in the prior art.

[0053] Therefore, the plants provided by the present invention can be characterized by including at least one flower, and preferably at least one flower per inclined branch is a flower at most 30 months old, at most 29 months old, at most 28 months old, at most 27 months old, at most 26 months old, or at most 25 months old. The term "age" refers to the period between the preparation of a renewable plant seed or plant part and the time when the first flower is formed on the plant. Preferably, the term "age" refers to the time between the planting of the seed or seedling and the time when the first flower is formed on the plant.

[0054] Pruning and / or controlled lighting according to the present invention is believed to be greatly involved in promoting flowering in plants. Therefore, the pruning according to the present invention can be used to advance the flowering time of plants of the Rubiaceae family, and the pruning is carried out on the cultivation shoot at a growth stage in which the cultivation shoot of the plant branches into an upright shoot and at least one oblique branch, and the pruning includes removing at least the upright shoot and leaving at least one oblique branch. Regarding the type of controlled lighting, the features described in connection with the cultivation in steps b and d of the method of the present invention are equally applicable to the use of the controlled lighting according to the present invention for advancing the flowering time of plants of the Rubiaceae family, particularly plants of the genus Coffea.

[0055] Hereinafter, the present invention will be described with reference to the drawings, which should not be construed as limiting the scope or intention of the present invention. The figures show an overview of the method according to the present invention.

Brief Description of the Drawings

[0056]

Figure 1

Figure 2

[0057] Example: Cultivation of plants of the genus Coffea Fifteen cuttings of the genotype / variety GPFA107 of Coffea arabica seedlings were prepared as plantable parts renewable at the start of implementing the method according to the present invention. The day on which the cuttings were carried out was designated as t0, indicating the start for determining the plant age. All cuttings were cultivated in small potted plants with soil in a greenhouse compartment at 17 - 25 °C and 72% RH. Ten of the cuttings were cultivated on a vertical shelf. These seedlings are also referred to as "Group 1". Here, the lighting was provided by LED plant growing lamps (Philips Green Power Module Production 120 cm - Deep Red / White - 50 μmol s -1 ) respectively, and the light was arranged at a distance of up to 50 cm from the plants with a photoperiod of 14 hours per day. Lighting by four 400 W high - pressure sodium lamps each was used at a distance of about 2.5 m from the soil surface with a photoperiod of 12 hours / day, and the remaining five cuttings were cultivated on a cultivation bench. These cuttings are also referred to as "Group 2". During cultivation, the plant parts were fertilized and irrigated twice a day with a dripper.

[0058] The plants were inspected about once a month for the development of the branching part. The branching part indicates the occurrence of a cultivation shoot as defined herein. About 17 - 19 months after t0, a branching part that branches into an upright shoot and at least one inclined branch appeared in each of the plants. The cultivation shoots of Group 1 were pruned by removing the upright shoot and all inclined branches except one. The cut was made at a distance of about 2 - 3 mm distal to the branching part. The cultivation shoots of Group 2 were not pruned.

[0059] After pruning the plants in Group 1, the plants in both groups were further cultivated until 30 months after t0. Starting from 25 months after t0, the number of flower buds, flowers, and visible fruits was counted for each plant once a month. The first flower appeared on the plants in Group 1 after an approximately 25 - 26 month cultivation period.

[0060] Immediately after flowering, all the flowers were hand - self - pollinated. The number of pollinated flowers per inclined branch was counted by determining whether seeds were formed. Further, the number of visible fruits for each plant was counted. The numbers were averaged within each group, that is, Group 1 consisting of pruned coffee trees; and Group 2 consisting of un - pruned coffee trees.

[0061] Table 1 shows the data for Group 1 and Group 2. "pp" means per plant; "pb" means per inclined branch.

[0062]

Table 1

[0063] This example shows that pruning and / or controlled lighting according to the present invention resulted in an increase in the total number of buds per inclined branch. In particular, the number of nodes with flower buds showed a first maximum after 26 months, then decreased and then increased again, which indicates that second - generation flowers began to form in the pruned plants 2 - 3 months after the cultivation of the flowering shoots. This effect was not observed in the un - pruned plants.

[0064] Furthermore, pruning resulted in an increase in the number of nodes with flower buds per inclined branch, and more importantly, an increase in the number of pollinated flowers and visible fruits per inclined branch. Only by the method according to the present invention, plants with more than one flower per inclined branch occurred after 26 months of cultivation.

[0065] The examples show that the method according to the invention can significantly and surely increase the number of fruits that can be obtained after a short cultivation period.

[0066] Finally, 296 seeds were taken from the cherries collected from the pruned trees and placed under germination conditions to evaluate the viability. A total of 225 seeds germinated properly (76%) and changed into plants, indicating that this method is suitable for use in coffee seed production.

[0067] [Examples] Twenty-three GPFA70 (Arabica) seedlings and twenty-three GPFA107 (also Arabica) cuttings were planted and grown until they reached the first diagonal branch. For both varieties, 20 out of 23 plants were pruned according to this method and placed in a growth chamber with a controlled photoperiod (20 pruned trees, 10 - 14 hours of sunshine duration, average LED lighting 105 μmol m -2 s -1 ), and the remaining 3 plants were allowed to grow freely under greenhouse conditions (control: natural light cycle with light compensation using HPS lamps delivering 50 μmol.m -2 .s -1 , 3 unpruned trees).

[0068] The plants were regularly inspected for bud development at the node level, and the number of nodes showing bud development was recorded to measure the effect of pruning combined with LED lighting treatment. To evaluate the effect of pruning on this parameter, the bud density per diagonal branch was also calculated.

[0069] The development of the first diagonal branch appeared on the 135th day after cutting for the cuttings, while for the GPFA70 seedlings, it became observable on the 273rd day after planting. It was confirmed that when pruned and grown under LED light, there was earlier bud induction for both varieties compared to the control plants. As a result, for GPFA70 and GPFA107, buds appeared 153 days and 197 days earlier in the treated plants compared to the control plants respectively (Figure 2).

[0070] In the GPFA107 pruned plants derived from cuttings, earlier bud development was observed compared to the GPFA70 pruned plants derived from seedlings. This early development could not be observed in the control plants.

[0071] Even when higher variability can be observed, it was confirmed that in the pruned plants, the bud density per inclined branch was always higher compared to the control.

Claims

1. A method for shortening the time until flowering of a flower formed by a plant of the Rubiaceae family and / or increasing the number of flowers, comprising: a. preparing a renewable plant seed or plant part; b. cultivating the plant seed or plant part until a cultivation shoot is obtained, the cultivation shoot including a branched part where an upright shoot and at least two oblique branches have developed; c. pruning at the branched part of the cultivation shoot by removing at least the upright shoot and leaving at least one oblique branch to obtain a pruned shoot; d. cultivating the pruned shoot until a flower is formed on at least one of the oblique branches to obtain a flowering shoot; A method comprising the above steps.

2. The cultivation shoot obtained in step b and pruned in step c includes only one branched part, and / or the branched part described in step b and used for pruning in step c is the first branched part developed in the cultivation shoot. The method according to claim 1.

3. The method according to claim 1 or 2, wherein the cultivation in step d further includes continuously removing any newly formed upright shoots.

4. The method according to any one of claims 1 to 3, characterized in that it includes a step e of bud formation occurring 250 days later, preferably 220 days later, from a further rooting cutting following step d.

5. The method according to any one of claims 1 to 4, characterized in that it includes a step e of bud formation occurring 380 days later, preferably 340 days later, from sowing following step d.

6. The cultivation in step d includes specifically stimulating the remaining at least one oblique branch by exposure to a light source that illuminates the at least one oblique branch, the light source being arranged at a distance of 2 to 50 cm from the surface of the at least one oblique branch and emitting light in a spectral range of 400 to 750 nm. The method according to any one of claims 1 to 5.

7. The method according to any one of claims 1 to 6, characterized in that the cultivation in step b is carried out indoors and includes illumination with a photoperiod of 8 to 14 hours per day.

8. During said cultivation in step b and / or step d, the illumination is set such that the plant receives natural light and / or artificial light having a photosynthetic photon flux density of 80 to 1500 μmol m －２ s －１ The method according to any one of claims 1 to 7, characterized in that.

9. The method according to any one of claims 1 to 8, characterized in that the cultivation in step b and / or step d is carried out while completely or partially blocking natural light.

10. The method according to claim 9, characterized in that the blocking of the natural light is carried out only in step d, preferably only during the photoperiod outside.

11. The method according to any one of claims 1 to 10, characterized in that the cultivation in step b and / or step d includes growth at 16 to 35 °C, 60 to 95% RH, and fertilization irrigation.

12. The method according to any one of claims 1 to 11, characterized by not including hormone treatment and genetic manipulation.

13. The method according to any one of claims 1 to 12, characterized in that the plant is of the genus Coffea.

14. A plant of the Rubiaceae family containing at least one flower per obliquely branched shoot, obtained by the method according to any one of claims 1 to 13, characterized in that the plant is at most 30 months old.

15. The plant according to claim 14, characterized in that it is a variant showing male sterility.

16. Use of the plant according to claim 14 or 15 for producing fruits and / or seeds or in a breeding program.

17. Use of controlled lighting and / or pruning to shorten the time to flowering of the flowers formed by a plant of the Rubiaceae family and / or to increase the number of flowers, wherein the pruning is carried out on the cultivated shoot at a growth stage where the cultivated shoot of the plant has branched into an upright shoot and at least two obliquely branched shoots, and the pruning includes removing at least the upright shoot and leaving at least one obliquely branched shoot.

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