Method and device for determining the vase-life of cut-flowers by plant acoustics

Abstract

The invention provides a method for estimating a vase-life of a cut plant product (1), wherein the cut plant product (1) is selected from the group comprising a cut flower and cut foliage, wherein the method comprises: (A) a cooling stage comprising subjecting the cut plant product (1) to a cooling temperature (TC) for a cooling duration (tC), wherein the cooling temperature (TC) is selected from the range of 0 – 10 ºC, and wherein the cooling duration (tC) is selected from the range of 0.5 – 4 weeks; (B) a detection stage comprising detecting acoustic emission radiation (2) from the cut plant product (1) and providing an emission-related signal (3); and (C) an analysis stage comprising determining a settling time (τS) based on the emission- related signal (3), and determining the vase-life based on the settling time (τS).

Description

[0001] Method and device for determining the vase-life of cut-flowers by plant acoustics

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a method for estimating a vase-life of a cut plant product. The invention further relates to a prediction method for providing a predicted vaselife of a plant prior to harvesting the plant. The invention further relates to a system for estimating a vase-life of a cut plant product.

[0004] BACKGROUND OF THE INVENTION

[0005] Methods for determining the vase-life of plant products are known in the art. For instance, DANESHMAND et al., “The water relation parameters are associated with the genotypic differences in the vase life of cut rose flowers”, Postharvest Biology and Technology, Volume 211, May 2024, describes an investigation of the role of xylem anatomy in the process related to the high / low or continuous / discontinuous water absorption during vase life, and the physiological responses of 11 commercial cut rose cultivars were determined to explore the relationship between cut flower vessel anatomy and transpirational water loss. The article describes that rose cultivars with a larger xylem diameter had the longest vase life, and that there was a positive association between these two variables.

[0006] DUTTA et al., “Ultrasound Pulse Emission Spectroscopy Method to Characterize Xylem Conduits in Plant Stems”, Research, September 2022, describes extraction of the xylem radii of xylem conduits in plants from the waveforms of ultrasound pulses using a model that relates the resonant vibrations of a vessel to its dimension and viscoelasticity.

[0007] US 2023363327 Al describes a method for determining a physical vessel parameter of a vascular tissue in a vascular plant, wherein the method comprises: a detection stage comprising detecting acoustic emission radiation from the vascular plant and providing an emission-related signal; and an analysis stage comprising determining the physical vessel parameter based on the emission-related signal, wherein the physical vessel parameter comprises an elasticity or a vessel dimension, and wherein the analysis stage comprises fitting at least part of the emission-related signal to a model of flexural modes of a cylindrical beam, and determining the physical vessel parameter based on the model.

[0008] SUMMARY OF THE INVENTION

[0009] Vase-life, defined as the duration cut plant products like flowers maintain aesthetic appeal post-harvest, is pivotal for assessing post-harvest longevity and market value. Water and nutrient transport in plants has attracted much attention in the last decades. In vascular plants, water and nutrient transport is handled by the vascular tissue. In particular, water transport may primarily be handled by xylem vessels, and nutrients produced from photosynthesis may primarily be transported by phloem vessels.

[0010] The deterioration of vase-life may be predominantly caused by embolisms and blockage in the xylem vessels after harvest, as xylem hydraulic conductance may be crucial for maintaining water balance in flower stalks.

[0011] Obtaining a better understanding of plant physiology as a function of age, genetic and environmental parameters is useful for growing and preserving crops, fruits, flowers and trees. In particular, xylem vessels are considered the life-supporting conduits for water and ionic nutrients in plants, and xylem dimensions may be indicative of water carrying capacity and stress resilience. If growers can measure in-plant parameters such as the xylem dimensions, this can be used to optimize growth, harvest and preservation conditions, which may facilitate a grower to improve vase-life of the plants after harvest.

[0012] However, prior art techniques for determining a plant's vascular anatomy, such as optical microscopy and electron microscopy, may generally be destructive and time consuming. For example, current techniques may obtain vessel dimensions and other related parameters using (i) optical microscopy, (ii) latex paint-infusion coupled to optical microscopy, (iii) scanning electron microscopy, and (iv) uniaxial tensile loading. For all these techniques, the plant may generally need to be cut into pieces to obtain data. Thereby, prior art methods may be wasteful as the plants may (at least partially) be damaged or even destroyed, such that their vascular tissue cannot be studied as a function of time.

[0013] Further, prior art methods may primarily involve monitoring water loss to detect the cessation of transpiration, which may be indicative of vessel cavitation saturation. Such monitoring may typically be achieved by periodically weighing cut flowers submerged in water, with the cessation of weight loss marking the end of vase-life. Such prior art methods for determining vase-life, involving visual inspection and physiological monitoring, may be costly and labor-intensive, often extending over several days to weeks. Hence, prior art methods may be time-consuming, e.g., requiring weeks of monitoring of the plant, labor-intensive, and may be incompatible with execution in a high throughput system.

[0014] Prior art methods may further involve exposing the cut plant material to conditions that differ from those conditions typically experienced by cut plant material, which may result in a mismatch between the predicted vase-life and practically observed vase-life. Hence, it is an aspect of the invention to provide an alternative method for estimating the vase-life of a cut plant product, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0015] In a first aspect, the invention may provide a method for estimating a vase-life of a cut plant product. In embodiments, the cut plant product may be selected from the group comprising a cut flower and cut foliage. The method may comprise a cooling stage comprising subjecting the cut plant product to a cooling temperature (Tc) for a cooling duration (tc). In embodiments, the cooling temperature (Tc) may be selected from the range of 0 - 10 °C. Further, in embodiments, the cooling duration (tc) may be selected from the range of 0.5 - 4 weeks. The method may further comprise a detection stage comprising detecting acoustic emission radiation from the (cooled) cut plant product and providing an emission-related signal. In further embodiments, the method may comprise an analysis stage comprising determining a settling time (is) based on the emission-related signal, and determining the vase-life based on the settling time (is). Hence, in specific embodiments, the invention may provide a method for estimating a vase-life of a cut plant product, wherein the cut plant product is selected from the group comprising a cut flower and cut foliage, wherein the method comprises: (A) a cooling stage comprising subjecting the cut plant product to a cooling temperature (Tc) for a cooling duration (tc), wherein the cooling temperature (Tc) is selected from the range of 0 - 10 °C, and wherein the cooling duration (tc) is selected from the range of 0.5 - 4 weeks; (B) a detection stage comprising detecting acoustic emission radiation from the (cooled) cut plant product and providing an emission-related signal; and (C) an analysis stage comprising determining a settling time (is) based on the emission-related signal, and determining the vase-life based on the settling time (is).

[0016] The method of the invention may provide the benefit that a physical vessel parameter of a vascular tissue may be obtained both quickly and non-invasively. Hence, the physical vessel parameter may be obtained without damaging the plant. The physical vessel parameter may be used in the method of the invention to estimate a vase-life of the cut plant product, which information may be used by breeders to enhance plant characteristics. In particular, an extended vase-life results in an increased product quality, increased customer satisfaction, and logistical efficiency (by reducing the likelihood of wilting during transit delays). The method may especially achieve relatively high accuracy through using ultrasound pulses to characterize vascular vessel distribution in the plant product. In particular, the invention may provide a new platform for determining the vase-life of a cut plant product by implementing a sonographic method. The invention may be based on the observation that remotely recorded ultrasound emissions are a signature of the xylem vessel dimensions and elasticity and represent its resonant modes of vibration. In particular, by recording (spontaneous or) induced acoustic emission radiation, especially ultrasound emission radiation, of the plant, especially from the vascular tissue, data related to the vessel dimensions and / or vessel elasticities may be obtained in a non-destructive way. The invention may facilitate rapid in- vivo and / or ex vivo plant phenotyping. The invention may particularly relate to sending an external radiation pulse, especially an ultrasound pulse, through the plant product and recording induced acoustic emission radiation.

[0017] The method of the invention may further facilitate accounting for stresses that cut plant products are typically exposed to during transit from a cultivation site to a final destination, e.g., to a display site. In particular, the inventors have noted that the low temperatures that cut plant products are typically exposed to during transit may substantially affect the vase-life of the cut plant product. Such low temperatures may especially play a vital role in maintaining freshness and reducing transpiration losses that can lead to wilting or discoloration (yellowing / browning) of flowers during transit. The cooling stage may comprise or simulate such cooled transit, thereby providing a more practically relevant vase-life estimate.

[0018] In particular, the invention may provide a non-destructive method for determining a vase-life of a cut plant product based on a vessel dimension and / or a settling time (TS). Hence, the invention may provide a method for estimating a vase-life of a cut plant product (also: “plant”). The method may facilitate a high-throughput analysis, such as by sequentially analyzing different plants arranged on a conveyor belt. The acoustic measurements of the method may further be more sensitive to small variations in xylem characteristics than state- of-the-art measurement methods, therewith providing a relatively more comprehensive and accurate reflection of water transport dynamics (and its impact on vase-life) of plants. Unlike optical microscopy methods, which are time-consuming and invasive, acoustic measurements capture the functional state over a broader scope of the xylem network in plants, offering a more holistic view of the cut plant.

[0019] Integrating acoustic measurements of the method into the cultivation and postharvest supply chain may improve the precision and speed of sorting plants and ensuring that only the highest-quality plants with desired vase-life reach the market. The method, i.e., the acoustic measurement approach combined with the cooling stage, may further support a continuous, automated monitoring and may create a scalable and data-driven system that may be aligned with precision agriculture and smart farming initiatives.

[0020] The term “vase-life” may herein especially refer to the duration cut plant products like flowers maintain aesthetic appeal post-harvest.

[0021] Further, the term “cut plant product” may especially refer to a plant product, such as a plant stem, a shoot, a flower, or foliage, that was harvested (e.g. “cut” or “physically separated”) from its root system.

[0022] The method of the invention may especially comprise estimating a vase-life of a cut plant product based on physical vessel parameters of the plant.

[0023] The term “physical vessel parameter” may herein especially refer to a vessel parameter such as or related to: a length, an area, a volume, a thickness, a viscosity and an elasticity. The term “physical vessel parameter” may also refer to a plurality of (different) physical vessel parameters. In embodiments, the physical vessel parameter may be a geometrical parameter.

[0024] In embodiments, the plant product may comprise a plant product harvested from a vascular plant. The term “vascular plant” may herein refer to any plant that has vascular tissue. Further, the term “vascular plant” may herein refer to any plant from the Clade Tracheophytes.

[0025] Vascular tissue may be a (specialized) tissue for distributing resources through the vascular plant. Vascular tissue may generally be subdivided into the xylem and phloem, which may be closely associated and may often be arranged directly adjacent to one another in a vascular plant, especially in a vascular bundle. In embodiments, the vascular tissue may especially be the xylem. In further embodiments, the vascular tissue may especially be the phloem.

[0026] In embodiments, the method may be a non-destructive method, i.e., the method may not damage, especially not destroy, the plant product.

[0027] The method may especially be an ex vivo method, i.e., the method may be executed on a plant product or a tissue extract from a plant as opposed to whole, living, vascular plant. The plant product may be freshly harvested or harvested and preserved over some time (e.g. hours to weeks, see also further below). For example, in embodiments, the method may be applied for estimating a vase-life of a cut plant product after harvest and (i) before transit, (ii) during transit (e.g. during transport in a vehicle designed to cool the plant products, such as cold sea containers), or (iii) after transit. Especially, in embodiments, the plant may be grown in a first location, a plant product may be harvested, and the plant product may be transported to be displayed in a second location. In such embodiments, the first location and the second location may be separated by at least 20 km, such as at least 50 km, like at least 100 km, especially at least 125 km.

[0028] The cut plant product may especially be a (fresh) cut flower. Further, in embodiments, the cut plant product may be (fresh) cut foliage. Hence, in embodiments, the cut plant product may be selected from the group comprising a cut flower and cut foliage.

[0029] In specific embodiments, the cut plant product may comprise a cut stem of a flower selected from the group comprising a cut Chrysanthemum flower, a Rosa flower, a Gerbera flower, a Hydrangea flower, a Carnation flower, an Anthurium flower, a Tulipa flower, an Orchid flower, a Gladiolus flower, a Lilium flower, a Heliconia flower, a Narcissus flower, a Strelitzia flower and an Alstroemeria flower. Especially, the cut plant product may comprise a (cut stem of a) Chrysanthemum flower. Yet, in specific embodiments, the cut plant product may comprise a cut stem of foliage selected from the group comprising an Acacia, a Dracaena, an Astragalus, a Trifolium, and a Mimosa. Especially, the cut plant product may comprise a (cut stem of a)n Acacia or a Dracaena. It will be clear to the person skilled in the art that relationships between acoustic properties and vase-life may vary for different plants. Hence, (slight) plant-specific or crop-specific adjustments may be made to tailor the method of the invention to specific plants, thereby improving the vase-life prediction for specific plants.

[0030] Additionally or alternatively, the method may be an in vivo method, i.e., the method may be executed on a whole, living, vascular plant as opposed to only on a tissue extract or a dead vascular plant. The vascular plant may be arranged in a substrate, such as soil. The vascular plant may especially be a whole vascular plant. The vascular plant may especially be a living vascular plant.

[0031] In embodiments, the method may comprise one or more of a cooling stage, a detection stage, and an analysis stage.

[0032] The cooling stage may especially comprise subjecting the cut plant product to a cooling temperature (Tc) for a cooling duration (tc). In embodiments, the cooling temperature (Tc) may be selected from the range of > -7 °C, such as from the range of > -4 °C, like from the range of > -2 °C, especially from the range of > 0 °C. Moreover, in embodiments, the cooling temperature (Tc) may be selected from the range of <20 °C, such as from the range of < 15 °C, like from the range of < 10 °C, especially from the range of < 8 °C. Especially, in embodiments, the cooling temperature (Tc) may be selected from the range of 0-8 °C, such as from the range of 1-6 °C, like from the range of 2-5 °C. In embodiments, the cooling duration (tc) may be at least 4 hours, such as at least 8 hours, like at least 12 hours, especially at least 24 hours. Especially, in embodiments, the cooling duration (tc) may be at least a day, such as at least two days, like at least three days, especially at least five days. Moreover, in embodiments, the cooling duration (tc) may be at most two months, such as at most one month, like at most four weeks, especially at most two weeks. In specific embodiments, the cooling duration (tc) may be selected from the range of 0.5-6 weeks, such as from the range of 0.5-4 weeks, like from the range of 1-3 weeks.

[0033] In specific embodiments, the cooling temperature (Tc) may be selected from the range of 1-6 °C, and the cooling duration (tc) may be selected from the range of 1-3 weeks. Such embodiments may provide the benefit that transpiration and the process of wilting of the cut plant product may be slowed down, therewith improving the quality and vase-life of the plant product. Furthermore, such cooling may be beneficial in preserving cut plant products during transit delays.

[0034] Subjecting the cut plant product to the cooling temperature (Tc) may for example be achieved through transport of the cut plant product in a cooling vehicle, such as a cooling truck or a cooled sea container. Additionally or alternatively, in embodiments, subjecting the cut plant product to the cooling temperature (Tc) may be achieved through static (rather than in-transit) cooling of the cut plant product, e.g. in a refrigerator or cooled storage space.

[0035] As described above, the method may further comprise a detection stage. In embodiments, the detection stage may be performed during (at least part of) the cooling stage. Alternatively, in embodiments, the detection stage may be performed after the cooling stage.

[0036] In embodiments, the detection stage may comprise detecting acoustic emission radiation from the (cooled) cut plant product. The detection stage may further comprise providing an emission-related signal. Especially, the detection stage may comprise detecting acoustic resonance emission radiation from a cut plant product, especially from the vascular tissue of the cut plant product, and providing an emission-related signal. It will be clear to the person skilled in the art that, strictly speaking, the measured (or “observed”) frequency of acoustic emission radiation may be slightly lower than the true resonant frequency due to nonzero damping.

[0037] The term “acoustic emission radiation” may herein refer to acoustic radiation emitted from the cut plant product (e.g. flower), especially from the vascular tissue of the cut plant product. In embodiments, the cut plant product, especially the vascular tissue of the cut plant product, may emit acoustic emission radiation without specifically being excited by external factors. For instance, if a plant experiences drought stress, gas bubbles can nucleate in these vessels, which may result in emission radiation, especially ultrasound emission radiation, being emitted from the plant. Additionally or alternatively, in embodiments, the cut plant product, especially from the vascular tissue of the cut plant product, may have been excited by external factors, such as with acoustic excitation radiation in an excitation stage (see also further below), and may subsequently emit acoustic emission radiation.

[0038] The term “resonance acoustic emission radiation” may herein especially refer to radiation emitted from the cut plant product, especially from the vascular tissue of the cut plant product, that matches an (internal) resonance frequency of the vascular tissue. In particular, the acoustic excitation radiation may comprise radiation having a resonance frequency of the vascular tissue, i.e., radiation having a frequency matching a natural frequency of vibration of the vascular tissue, which may cause the vascular tissue to vibrate and emit resonance acoustic emission radiation at the resonance frequency.

[0039] The acoustic emission radiation may comprise radiation having the same frequency as the acoustic excitation radiation. The term “frequency” may also refer to a plurality of different frequencies. In general, in embodiments, the acoustic emission radiation may be selected from the range of 1 - 250 kHz, such as from the range of 10 - 200 kHz.

[0040] In embodiments, the acoustic emission radiation may comprise radiation having a frequency of at least 1 kHz, such as at least 5 kHz, especially at least 10 kHz, such as at least 20 kHz, such as at least 30 kHz.

[0041] In further embodiments, the acoustic emission radiation may comprise radiation having a frequency of at most 500 kHz, especially at most 250 kHz, such as at most 200 kHz, especially at most 170 kHz, such as at most 150 kHz, especially at most 130 kHz.

[0042] In further embodiments, the emission radiation may be ultrasound emission radiation, i.e., the emission radiation may comprise radiation in the ultrasound range.

[0043] The term “emission-related signal” may herein refer to a signal that is related to the detected acoustic emission radiation. In particular, the emission-related signal may comprise raw and / or processed data related to the (detected) acoustic emission radiation.

[0044] In embodiments, the acoustic emission radiation may for example be detected using one or more of a microphone, a receptor, an acoustic emission sensor (such as resonant or wideband sensors), an amplifier, and a transducer.

[0045] The cut plant product may, in embodiments, be elongated along a longitudinal axis, such as along a stem. Further, in embodiments, the vascular tissue, especially the xylem, may have a longitudinal axis. In particular, in general, the longitudinal axis may be parallel to an axis of elongation of a plant stem and / or a plant branch (comprising the vascular tissue).

[0046] In embodiments, the detection stage may comprise detecting acoustic emission radiation from the vascular plant at a first location arranged axially with respect to the longitudinal axis, i.e., the first location may essentially be arranged on the longitudinal axis. Such an arrangement may facilitate identifying radiation, especially a sound wave, that resonates and propagates along the length of the vessels. The frequencies may be governed by the vessel length, while damping (of the sound) in the time-domain may relate to the vessel radii and / or the kinematic viscosity of the sap present in the vessels.

[0047] In further embodiments, the detection stage may comprise detecting acoustic emission radiation from the vascular plant at a second location arranged perpendicular (or “arranged radially”) with respect to the longitudinal axis, i.e., the second location may be arranged along the plant stem (or the plant branch) and perpendicular to the longitudinal axis. Such an arrangement may facilitate identifying radiation, especially a sound wave, that is generated by the flexural and / or radial vibration modes of a vessel-sap composite. The corresponding frequencies may be governed by one or more of the length, radius, and elastic modulus of the vessels.

[0048] In particular, in further embodiments, the detection stage may comprise detecting acoustic emission radiation from the cut plant product at both the first location and the second location.

[0049] Further, in embodiments, the method may comprise the analysis stage. In embodiments, the analysis stage may comprise determining a settling time (is) based on the emission-related signal, and determining the vase-life based on the setting time (TS).

[0050] In particular, especially with regards to xylem, the acoustic emission radiation measured from the first location may be informative with regards to one or more of a xylem vessel (element) length L, a xylem radius R, an elastic modulus E, a sap (water) density pi, a bulk compressibility of sap K, a xylem wall thickness h, and a dynamic viscosity qi. In particular, the acoustic emission radiation detected at the first location may comprise an observed mthorder (resonance) frequency fm, wherein fmmay (approximately) equal m / 2*veff / L, i.e.,: wherein m is the mode order, and wherein:

[0051] Further, the acoustic emission radiation detected at the first location may dampen (in the time domain), wherein the dampening may be characterized by an emission radiation settling time TS, wherein:

[0052] Hence, the acoustic emission radiation may have a settling time (TS). The setting time (TS) may herein be defined as the duration it takes for an emission signal strength to decrease to 5% or less of an excitation radiation signal strength. Hence, if, at the first location, the frequency of the observed acoustic emission radiation from a vascular tissue is higher than that of a reference vascular tissue, this may be indicative of the vascular tissue having a higher value for one or more of an elastic modulus E, a bulk compressibility of sap K, a xylem wall thickness h, or a lower value for one or more of a xylem vessel (element) length L, a xylem radius R or a sap (water) density pi. Similarly, if the settling time TS. of the observed acoustic emission radiation from a vascular tissue is higher than that of a reference vascular tissue, this may be indicative of the vascular tissue having a higher value for one or more of the xylem radius and the sap (water) density pi, or of a lower value of the dynamic viscosity qi.

[0053] Similarly, especially with regards to xylem, the acoustic emission radiation measured from the second location may be informative with regards to one or more of a xylem vessel (element) length L, a xylem radius R, an elastic modulus E, a xylem mass density pxyiem, and a solid viscoelasticity T|soiid. In particular, the acoustic emission radiation detected at the second location may comprise an observed nthorder (resonance) frequency fn, wherein: wherein k r is a mode constant, i.e., a pre-factor that occurs in the expression of the resonance frequency of a vibrating beam. The value may depend on the order “n”. In particular, in embodiments, for n = 1, 2, or 3, k r may be 4.73, 7.8532, or 10.996 respectively. For n >3, k r may be about (n+0.5)*7t. The correct mode constant may be known by identifying which set of theoretical characteristic frequencies is a close match with the observed set of characteristic frequencies. Further, the acoustic emission radiation detected at the first location may dampen (in the time domain), wherein the dampening may be characterized by a settling time TS, wherein:

[0054] Hence, if, at the second location, the frequency of the observed acoustic emission radiation from a vascular tissue is higher than that of a reference vascular tissue, this may be indicative of the vascular tissue having a higher value for one or more of the elastic modulus E and a xylem radius R, or a lower value for one or more of a xylem vessel (element) length L, and a xylem mass density pxyiem. Similarly, if the settling time TS. of the observed acoustic emission radiation from a vascular tissue is higher than that of a reference vascular tissue, this may be indicative of the vascular tissue having a higher value for the solid viscoelasticity T|soiid, or a lower value for the elastic modulus E.

[0055] It will be clear to the person skilled in the art that the physical vessel parameters may further vary as a function of other (measurable) features. For example, the elastic modulus and the xylem mass density may also depend on water / moisture content of the xylem tissue.

[0056] Hence, in embodiments, the analysis stage may comprise determining a settling time (TS) based on the emission-related signal, and determining the vase-life based on the settling time (TS). In such embodiments, a model may be provided using available or newly collected data to (substantially accurately) correlate the vase-life of the cut plant product to the settling time (TS). Especially, a model may be trained using available or newly collected data to (substantially accurately) correlate the vase-life of the cut plant to the settling time (TS) using machine learning.

[0057] Moreover, in embodiments, the analysis stage may comprise determining a (xylem) vessel dimension based on the settling time (TS), and determining the vase-life based on the vessel dimension.

[0058] In embodiments, the vessel dimension may be selected from one or more of: a (xylem) vessel radius, a (xylem) vessel length, a (xylem) vessel elasticity, and a (xylem) wall thickness. Hence, in embodiments the physical vessel parameter may comprise one or more of a (xylem) vessel radius, a (xylem) vessel length, a (xylem) vessel elasticity, and a (xylem) wall thickness.

[0059] The invention will herein, for explanatory purposes, primarily be described in the context of embodiments related to the determination of xylem vessel parameters. It will be clear to the person skilled in the art that the invention is not limited to such embodiments, and that the invention may further apply to the determination of phloem vessel parameters. The analysis stage may comprise determining the physical vessel parameter based on the emission-related signal. In particular, the detected acoustic emission radiation may represent one or more resonant modes of vibration of the dimensions and elasticity of the vascular tissue, such as of a xylem tissue. The resonant modes of vibration may relate to the dimensions and elasticity of the vascular tissue of the cut plant product. Hence, the detected acoustic emission radiation may be a signature of the vascular tissue dimensions and elasticity. The physical vessel parameter may especially comprise an elasticity or a vessel dimension, especially an elasticity, or especially a vessel dimension. In particular, the physical vessel parameter may comprise an elasticity or a vessel dimension of the vascular tissue, especially of a vessel (element) of the vascular tissue. In embodiments, the vessel dimension may especially comprise a vessel length or a vessel radius, especially a vessel length, or especially a vessel radius.

[0060] In embodiments, a decaying part of the detected acoustic emission radiation may especially be used to determine (i.e. calculating) the settling time (TS) using curve fitting. Subsequently, in embodiments, a model may be fit based on the determined settling time (TS) to describe the vase life of the cut plant product.

[0061] Especially, in embodiments, the analysis stage may comprise determining one or more parameters selected from the group comprising: a settling time (TS), a frequency (f) (of the acoustic emission radiation), a time of flight (tof) (of the acoustic emission radiation), a power spectrum (or “power spectral density”), phase shift ((|>), and an amplitude (A) (of the acoustic emission radiation), based on the emission-related signal. Herein, the time of flight may be assumed as the time it takes acoustic radiation (or ultrasound) to go through air and the cut plant product, starting from its respective source (e.g. the plant or a speaker, see also further below) up until it is detected by a sensor (or microphone).

[0062] The vessel dimension may subsequently, in embodiments, be determined by fitting the settling time (TS) and / or one or more of the parameters (as defined above) to a model. Especially, in embodiments, the model may be selected from the group comprising: (i) a model of flexural modes (or: “bending modes”), (iii) a model of breathing modes, and (iv) a model of radial modes. Moreover, in embodiments, more than one model may be applied. Hence, in such embodiments, the method may comprise fitting one or more of the settling time (TS) and (one or more of) the abovementioned parameter(s) to one or more models selected from the group comprising a flexural mode model (e.g. of a cylindrical beam), a breathing mode model, and a radial mode model. In particular, the analysis stage may comprise determining a parameters selected from the group comprising: a frequency (f), a time of flight (tof), a power spectrum (or “power spectral density”), phase shift ((|>), and an amplitude (A), based on the emission-related signal. In such embodiments, the method may further comprise fitting one or more of the settling time (TS) and the parameter to a model selected from the group comprising a flexural mode model (e.g. of a cylindrical beam), a breathing mode model, and a radial mode model, especially wherein the method comprises determining the vessel dimension based on the (fitted) model. The flexural mode model may, in further embodiments, especially be a model of the flexural mode(s) of a cylindrical beam.

[0063] Herein, the term “flexural modes” may refer to a type of acoustic propagation along a longitudinal direction of a three-dimensional object, such as the (cut stem of the) cut plant product, that is visualized as a shaking of the object across its diameter. Further, the term “breathing modes” my refer to a collective oscillation of a system, such as the (cut stem of the) cut plant product, that expands and contracts. Yet further, the term “radial modes” may refer to long-period oscillations that describe the radial expansion and contraction of the (cut stem of the) cut plant product.

[0064] The analysis stage may thus comprise fitting the detected parameters (and parameters directly derived therefrom i.e., the emission-related signal, a frequency, a time of flight, an amplitude, and a settling time) to a model to determine the vessel dimension (and therewith the vase-life).

[0065] Hence, in specific embodiments, the analysis stage further comprises determining one or more parameters selected from the group comprising: a frequency (f), a time of flight (tof), a power spectrum (or “power spectral density”), phase shift (4>),and an amplitude (A), based on the emission-related signal; fitting one or more of the settling time (TS) and the parameter to a model selected from the group comprising a flexural mode model, a breathing mode model, and a radial mode model; and determining the vessel dimension based on the model.

[0066] In further embodiments, the method may comprise an excitation stage. The excitation stage may comprise providing acoustic excitation radiation to the cut plant product, such as to a cut flower. In particular, the excitation stage may comprise exposing the cut plant product, especially the vascular tissue, to the acoustic excitation radiation. The term “acoustic excitation radiation” may herein refer to acoustic radiation having a frequency suitable to excite the cut plant product, especially to a vascular tissue of the cut plant product. In particular, the acoustic excitation radiation may comprise a frequency suitable to excite an (internal) resonance of the cut plant product, especially of the vascular tissue, such as of the xylem. In particular, following excitation by the acoustic excitation radiation, the cut plant product may emit acoustic emission radiation, which may be detected in the detection stage. Hence, the excitation stage may be temporally arranged prior to the detection stage. It will be clear to the person skilled in the art that the frequency suitable to excite an (internal) resonance of the cut plant product may depend on the type and / or size of the cut plant product. For example, relatively low frequencies may be selected for the acoustic excitation radiation when employing the method in relation to a relatively large plant product, such as a tree trunk, whereas relatively high frequencies may be selected when employing the method in relation to a relatively small plant product, such as a flower. In particular, in embodiments, the acoustic excitation radiation may especially comprise radiation having a frequency selected from the range of 0.5 - 1000 kHz, especially from the range of 1 - 500 kHz, such as from the range of 10 - 250 kHz.

[0067] In embodiments, the acoustic excitation radiation may comprise radiation having a frequency of at least 1 kHz, such as at least 5 kHz, especially at least 10 kHz, such as at least 20 kHz, especially at least 30 kHz.

[0068] In further embodiments, the acoustic excitation radiation may comprise radiation having an (acoustic excitation radiation) frequency of at most 1000 kHz, such as at most 750 kHz, like at most 500 kHz. Especially, in embodiments, the acoustic excitation radiation may comprise radiation having an (acoustic excitation radiation) frequency of at most 250 kHz, such as at most 200 kHz, especially at most 170 kHz, such as at most 150 kHz, especially at most 130 kHz.

[0069] Radiation above 20 kHz may generally be referred to as ultrasound radiation, i.e., radiation with frequencies higher than the upper audible limit of human hearing. In further embodiments, the excitation radiation may be ultrasound excitation radiation, i.e., the excitation radiation may comprise radiation having a frequency in the ultrasound range.

[0070] In further embodiments, the acoustic excitation radiation frequency and / or acoustic excitation radiation amplitude may be varied in time, especially while the emitted radiation spectra and variations therein are determined to infer properties of the cut plant product, especially of the vascular tissue, or to determine acoustic excitation radiation frequencies at which acoustic emission radiation emission is stimulated most by the acoustic excitation radiation. In embodiments, the acoustic excitation radiation may especially be provided via one of a pulse, a wavelet, and a continuous wave, so long as a settling time may be measurable. Using a continuous wave may be beneficial as more power may be used, which may be especially useful when a frequency of interest in already known. Conversely, using a pulse may provide a relatively simple protocol for testing a wide range of (or even all) potentially relevant frequencies. In further embodiments, excitation pulses (e.g. block pulses) of different duration and amplitudes may be applied, especially where the frequency content depends on the pulse width.

[0071] The acoustic excitation radiation may especially comprise broadband radiation. In embodiments, the acoustic excitation radiation may comprise broadband radiation having one or more frequencies in the range of 1 - 500 kHz, especially in the range of 10-150 kHz.

[0072] In embodiments, the excitation stage may comprise providing acoustic excitation radiation (e.g. via a pulse), especially wherein the acoustic excitation radiation has an excitation duration (te) that is larger than a characteristic settling time due to damping in the vascular tissue (of the cut plant product). Hence, in embodiments, the excitation stage may comprise providing the acoustic excitation radiation for an excitation duration (te), wherein the acoustic excitation radiation may have a characteristic settling time (due to damping) in (a vascular tissue of the) cut plant product, wherein the excitation duration (te) may be larger than the characteristic settling time.

[0073] In particular, the excitation duration (te) may be larger than 1 ps, such as larger than 4 ps, like larger than 10 ps, especially larger than 100 ps. In further embodiments, the excitation duration (te) may be selected from the range of 4 ps - 50 ms, such as from the range of 0.1-25 ms, like from the range of 0.5-15 ms. In further embodiments, the excitation duration (te) may be at least 0.5 ms, such as at least 1 ms, especially at least 1.1 ms, such as at least 1.2 ms, especially at least 1.5 ms, such as at least 2 ms. In further embodiments, the excitation duration (te) may be at most 50 ms, such as at most 20 ms, especially at least 10 ms, such as at most 5 ms, especially at most 3 ms, such as at most 2 ms. In further embodiments, the excitation stage may comprise providing the acoustic excitation radiation via a step excitation or a narrow rectangular pulse. The settling time may especially be determined by fitting an amplitudeenvelope to a time-domain signal with a single exponential function.

[0074] The characteristic settling time may especially be replicated using known frequencies and pulse durations of natural emissions.

[0075] In further embodiments, the acoustic excitation radiation may have a excitation duration (te) smaller than the time-of-fhght (propagation time) of the acoustic excitation radiation through the plant, such as through the plant stem, especially through the vascular tissue. Hence, in embodiments, the excitation stage may comprise providing the acoustic excitation radiation for an excitation duration (te), wherein the excitation duration (te) may be smaller than a time-of-flight of the acoustic excitation radiation through (a vascular tissue of) the cut plant product. Such an embodiment may be beneficial as it may prevent a temporal overlap between acoustic excitation radiation and acoustic emission radiation exiting the plant. In particular, such embodiments may be beneficial when the damping (over time) of the acoustic emission radiation is used to determine the physical vessel parameter.

[0076] In particular, the excitation stage may comprise providing acoustic excitation radiation via a pulse having a pulse duration TON, where only a single pulse may be provided during a delay time Tdeiay. The acoustic excitation radiation may have an acoustic excitation radiation settling time T, which may be determined by fitting an amplitude-envelope to an (observed) time-domain signal with a single exponential function. Similarly, the acoustic emission radiation may have an acoustic emission radiation settling time TS, which may be determined by fitting an amplitude-envelope to an (observed) time-domain signal with a single exponential function. In embodiments, Tdeiay > Ts, which may provide the benefit that the excitation of the vascular tissue due to a first pulse may be (mostly) settled down before the next pulse excites the vascular tissue. In further embodiments, T > TS, which may serve to prevent the settling time in the plant response to be limited by the settling time of the acoustic excitation radiation. In further embodiments, TON < 1 / fpiant, wherein fpiant is the highest resonance frequency of interest, such that a bandwidth of the acoustic excitation radiation extends above the highest resonance frequency of interest fpiant

[0077] Furthermore, in embodiments, the excitation stage may comprise an excitation frequency sweep from a first frequency to a second frequency. In other words, the excitation stage may comprise scanning a radio frequency band from a first frequency to a second frequency for detecting signals being transmitted therewithin. For example, in embodiments, the first frequency may be selected from the range of 1-100 kHz, such as from the range of 5- 75 kHz. In such embodiments, the second frequency may be selected from the range of 100- 500 kHz, such as from the range of 150-250 kHz.

[0078] Similarly, in embodiments, the detection stage may comprise an emission frequency sweep from the first frequency to the second frequency. In other words, the detection stage may comprise scanning a radio frequency band from a first frequency to a second frequency for detecting signals being transmitted therewithin. For example, in embodiments, the first frequency may be selected from the range of 1-100 kHz, such as from the range of 5- 75 kHz. In such embodiments, the second frequency may be selected from the range of 100- 500 kHz, such as from the range of 150-250 kHz.

[0079] In specific embodiments, the first frequency and the second frequency may both be selected from the range of 1-250 kHz, such as from the range of 2-200 kHz, like from the range of 3-175 kHz. Hence, in embodiments, one or more applies of: (A) the excitation stage comprises an excitation frequency sweep from a first frequency to a second frequency; and (B) the detection stage comprises an emission frequency sweep from the first frequency to the second frequency; wherein the first frequency and the second frequency are selected from the range of 1-250 kHz.

[0080] The prediction of vase-life of the cut plant product may be further improved by considering additional relevant parameters, such as (weather or lighting) conditions the (corresponding) plant has been exposed to. Hence, in embodiments, the method may comprise determining (or “predicting”) the vase life (also) on the basis of historical information. The term “historic information” may herein refer to information related to the history of the plant from which the cut plant product was obtained. For instance, the historic information may include information on (a) soil conditions, (b) weather conditions, (c) lighting conditions, (d) irrigation conditions, (e) pest exposure, (f) pesticide exposure, (g) harvesting date, (h) transport conditions, et cetera. In embodiments, the method may comprise obtaining the historic data from a (dedicated) database, such as from an online database.

[0081] In another aspect, the invention provides a prediction method for providing a predicted vase-life of a plant prior to harvesting the plant. In embodiments, the prediction method may comprise harvesting a reference plant product to provide a (reference) cut plant product. The plant and the reference plant product may, in embodiments, be grown under similar conditions. Furthermore, in embodiments, the prediction method may comprise subjecting the cut plant product to the method (for determining a vase-life) as described above to provide a vase-life estimate for the reference plant product. In embodiments, the prediction method may further comprise predicting the vase-life of the plant based on the vase-life estimate for the reference plant product. Hence, in specific embodiments, the invention may provide a prediction method for providing a predicted vase-life of a plant prior to harvesting the plant, wherein the prediction method comprises harvesting a reference plant product to provide a cut plant product, wherein the plant and the reference plant product are grown under similar conditions, wherein the prediction method comprises subjecting the cut plant product to the method according to any one of the preceding claims to provide a vase-life estimate for the reference plant product, and wherein the prediction method further comprises predicting the vase-life of the plant based on the vase-life estimate for the reference plant product. Such a method may provide the benefit that plant breeders may gather data and vase-life estimates of their plants and crops prior to harvesting, which may be used to determine at what time to harvest a plant in order to achieve optimized vase-life of the harvested (or cut) plant product. As such, breeders may be enabled to improve their growth and transport efficiency while reducing plant waste due to premature wilting. Additionally or alternatively, the prediction method may provide insights for the detection of diseases or pathogens, which may reduce the vase-life of the plant, in the xylem vessels. As such, the prediction method may assist breeders in determining plant quality post-harvest and / or in devising possible treatment methods of affected plants pre-harvest.

[0082] In embodiments, the method may thus comprise performing measurements according to the above described method on a first (reference) plant (especially a cut plant, i.e., after harvesting), and using the results to provide (prior to harvesting) an estimated vase-life of the plant products of a second (target) plant.

[0083] The reference plant and the (target) plant may especially be grown under similar conditions. The term “similar conditions” may herein refer to conditions suitable for considering one plant to be a reasonable reference for the other plant. In particular, the (reference) plant and the (target) plant may be grown in (essentially) the same soil and / or under (essentially) the same lighting conditions, such as e.g. in the same (flower) bed or (plant) pot. In embodiments, the (reference) plant and the (target) plant may belong to the same species, especially to the same cultivar. In further embodiments, the (reference) plant and the (target) plant may be cultivated in the same geographic location. In further embodiments, the (reference) plant and the (target) plant may have been exposed to (essentially) the same nutrient conditions, such as to (essentially) the same amount of water and / or manure. In further embodiments, the (reference) plant and the (target) plant may have been exposed to (essentially) the same temperature conditions. In further embodiments, the (reference) plant and the (target) plant may have been exposed to (essentially) the same humidity conditions.

[0084] Although the conditions the reference plant and the plant are exposed to may be (essentially) the same, there may be some deviations. Hence, in embodiments, the prediction method comprises predicting the vase-life of the plant based on the vase-life estimate for the reference plant product and based on historic data for the plant and the reference plant.

[0085] For instance, a database may be developed comprising one or more of: predicted vase-life, observed vase-life, (xylem) vessel parameters, growth conditions (such as lighting, moisture, temperature, and pesticide control), harvesting dates, weather conditions (such as drought, storm, and amount and type of precipitation), and transport conditions (such as transport duration, temperature, and mode of transportation) of the (reference) plant and the (target) plant. Such a database may facilitate improving a prediction model, through which the accuracy of the prediction method may be improved over time. Hence, in embodiments, the prediction method may comprise obtaining reference data from a database, wherein the database comprises one or more of predicted vase-life, observed vase-life, (xylem) vessel parameters, growth conditions, harvesting dates, weather conditions, transport conditions, and plant types, and predicting the vase-life of the plant based on the vase-life estimate for the reference plant product and based on the reference data.

[0086] In a yet further aspect, the invention may provide a system for estimating a vaselife of a cut plant product. In embodiments, the cut plant product may be selected from the group comprising a cut flower and cut foliage. In further embodiments, the system may comprise a cooling arrangement, an acoustic radiation device and a control system. The system may especially have an operational mode. In embodiments, the operational mode may comprise a cooling stage, a detection stage and an analysis stage. In the cooling stage, in embodiments, the cooling arrangement may be configured to subject the cut plant product to a cooling temperature (Tc) for a cooling duration (tc). The cooling temperature (Tc) may especially be selected from the range of 0 - 10 °C. Furthermore, in embodiments, the cooling duration (tc) may be selected from the range of 0.5 - 4 weeks. Further, in embodiments, in the detection stage the acoustic radiation device may be configured to detect acoustic emission radiation from the (cooled) cut plant product. Additionally, in embodiments, in the detection stage the acoustic radiation device may be configured to provide an emission-related signal to the control system. Further, in embodiments, in the analysis stage the control system may be configured to determine a settling time (TS) based on the emission-related signal, and to determine the vaselife based on the settling time (TS). Hence, in specific embodiments, the invention may provide a system for estimating a vase-life of a cut plant product, wherein the cut plant product is selected from the group comprising a cut flower and cut foliage, wherein the system comprises a cooling arrangement, an acoustic radiation device and a control system, wherein the system has an operational mode, wherein the operational mode comprises a cooling stage, a detection stage and an analysis stage, wherein: (A) in the cooling stage the cooling arrangement is configured to subject the cut plant product to a cooling temperature (Tc) for a cooling duration (tc), wherein the cooling temperature (Tc) is selected from the range of 0 - 10 °C, and wherein the cooling duration (tc) is selected from the range of 0.5 - 4 weeks; (B) in the detection stage the acoustic radiation device is configured to detect acoustic emission radiation from the cut plant product and to provide an emission-related signal to the control system; and (C) in the analysis stage the control system is configured to determine a settling time (TS) based on the emission-related signal, and to determine the vase-life based on the settling time (TS). The system may provide the benefit that it may be used to obtain a physical vessel parameter of a vascular tissue both quickly and non-invasively. Hence, the physical vessel parameter may be obtained without damaging the plant. The system may be configured to use the physical vessel parameter to estimate a vase-life of the cut plant product, which information may be used by breeders to enhance plant characteristics. In particular, an extended vase-life may result in an increased product quality, increased customer satisfaction, and logistical efficiency (by reducing the likelihood of wilting during transit delays).

[0087] The system may make use of the observation that ultrasound emissions from a plant may be a signature of the xylem vessel dimensions and elasticity and represent its resonant modes of vibration. In particular, by recording (spontaneous or induced) acoustic emission radiation, especially ultrasound emission radiation, of the plant, especially from the vascular tissue, data related to the vessel dimensions and / or vessel elasticities may be obtained in a nondestructive way. In embodiments, the system comprises a cooling arrangement. The cooling arrangement may especially be configured to cool a cut plant product, such as to cool a cut plant product to a cooling temperature (Tc). In embodiments, the cooling temperature may be selected from the range of > -7 °C, such as from the range of > -4 °C, like from the range of > -2 °C, especially from the range of > 0 °C. Moreover, in embodiments, the cooling temperature (Tc) may be selected from the range of < 20 °C, such as from the range of < 15 °C, like from the range of < 10 °C, especially from the range of < 8 °C. Especially, in embodiments, the cooling temperature (Tc) may be selected from the range of 0-10 °C, especially from the range of 0-8 °C, such as from the range of 1-6 °C, like from the range of 2-5 °C. In embodiments, the cooling arrangement may comprise a static cooling arrangement. For example, in embodiments, the cooling arrangement may comprise one of a refrigerator or a cooled storage space. In such embodiments, cooling may preferably be achieved through thermoelectric cooling, liquid cooling, evaporative cooling, or heat-exchange, rather than ventilation and / or air-conditioning. Such embodiments may be beneficial to prevent the cut plant products from desiccating prematurely.

[0088] Additionally or alternatively, in embodiments, the cooling arrangement may be comprised by a transport vehicle, such as a cooled truck or a cooled sea container.

[0089] The system may further comprise an acoustic radiation device, especially an ultrasound device. In embodiments, the acoustic radiation device may comprise a radiation generation device, especially an ultrasound generation device. In further embodiments, the acoustic radiation device may comprise a radiation detection device, especially an ultrasound detection device. In specific embodiments, the radiation generation device and the radiation detection device may be the same device. Further, in embodiments, the acoustic radiation device may comprise one or more of a microphone, a receptor, an acoustic emission sensor, an amplifier, a transducer, a transmitter, and a speaker.

[0090] In embodiments, the radiation generation device may especially be configured to provide acoustic excitation radiation comprising radiation having a frequency selected from the range of 1 - 500 k Hz, especially from the range of 1 - 250 kHz, such as from the range of 10 - 200 kHz. In further embodiments, the radiation generation device may be configured to provide acoustic excitation radiation comprising radiation having a frequency of at least 1 kHz, such as at least 5 kHz, especially at least 10 kHz, such as at least 20 kHz, such as at least 30 kHz. In further embodiments, the radiation generation device may be configured to provide acoustic excitation radiation comprising radiation having a frequency of at most 500 kHz, especially at most 250 kHz, such as at most 200 kHz, especially at most 170 kHz, such as at most 150 kHz, especially at most 130 kHz.

[0091] In specific embodiments, the acoustic radiation device may comprise a radiation detection device. In further embodiments, the acoustic radiation device may be a radiation detection device. In embodiments, the radiation detection device may especially be configured to detect acoustic emission radiation comprising radiation having a frequency selected from the range of 1 - 500 kHz, especially from the range of 1 - 250 kHz, such as from the range of 10 - 200 kHz. In further embodiments, the radiation detection device may be configured to detect acoustic emission radiation comprising radiation having a frequency of at least 1 kHz, such as at least 5 kHz, especially at least 10 kHz, such as at least 20 kHz, such as at least 30 kHz. In further embodiments, the radiation detection device may be configured to detect acoustic emission radiation comprising radiation having a frequency of at most 500 kHz, especially at most 250 kHz, such as at most 200 kHz, especially at most 170 kHz, such as at most 150 kHz, especially at most 130 kHz. The acoustic radiation device, especially the radiation detection device, may be configured to detect acoustic emission radiation and to provide an emission- related signal to the control system, such as during the operational mode.

[0092] Hence, in embodiments, the system may further comprise the control system. The control system may especially be configured to control (at least part of) the system, such as to control the cooling arrangement and / or the acoustic radiation device. The term “controlling” and similar terms herein may especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and the element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one master control system may be a control system and one or more others may be slave control systems.

[0093] Further, the system, especially the control system, may have an operational mode. The term “operational mode” may also be indicated as “controlling mode”. The system, or apparatus, or device (see further also below) may execute an action in a “mode” or “operational mode” or “mode of operation”. Likewise, in a method an action, stage, or step may be executed in a “mode” or “operation mode” or “mode of operation”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another operational mode, or a plurality of other operational modes. Likewise, this does not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed. However, in embodiments, a control system may be available, that is adapted to provide at least the operational mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operational mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operational mode (i.e. “on”, without further tunability).

[0094] Hence, in embodiments, the control system may be configured to (have the system) execute an operational mode. The operational mode may comprise one or more of a cooling stage, a detection stage, and an analysis stage.

[0095] In the cooling stage, the cooling arrangement may (be configured to) subject the cut plant product to a cooling temperature (Tc) (also see above) for a cooling duration (tc). In embodiments, the cooling duration (tc) may be at least 4 hours, such as at least 8 hours, like at least 12 hours, especially at least 24 hours. Especially, in embodiments, the cooling duration (tc) may be at least a day, such as at least two days, like at least three days, especially at least five days. Moreover, in embodiments, the cooling duration (tc) may be at most two months, such as at most one month, like at most four weeks, especially at most two weeks. In specific embodiments, the cooling duration (tc) may be selected from the range of 0.5-6 weeks, such as from the range of 0.5-4 weeks, like from the range of 1-3 weeks.

[0096] In the detection stage the acoustic radiation device may (be configured to) detect acoustic emission radiation from the cut plant product and to provide an emission-related signal to the control system.

[0097] In the analysis stage the control system may (be configured to) determine the vase-life of the cut plant product based on the emission-related signal. In particular, the control system may (be configured to) determine a settling time (TS) based on the emission-related signal, and especially to determine the vase-life based on the settling time (TS).

[0098] In embodiments, the operational mode may further comprise an excitation stage, especially (temporally) preceding the detection stage. In the excitation stage, the acoustic radiation device, especially the radiation generation device, may (be configured to) provide acoustic excitation radiation to the cut plant product. In particular, the acoustic excitation radiation may be selected to induce the subsequent emission of acoustic emission radiation by the cut plant product. Hence, in such embodiments, in the detection stage, the acoustic radiation device, especially the radiation detection device, may be configured to detect the (induced) acoustic emission radiation and to provide an emission-related signal to the control system.

[0099] Yet further, in embodiments, the control system may be configured to (have the system) execute the method for estimating a vase-life of a cut plant product as described above or the prediction method as described above.

[0100] Embodiments as described above in relation to the method for estimating a vaselife of a cut plant product may thus mutatis mutandis apply to the system. Especially, in embodiments, the operational mode may further comprise an excitation stage. Especially, in the excitation stage the acoustic radiation device may be configured to provide acoustic excitation radiation to the cut plant product. Further, in embodiments, the acoustic excitation radiation may comprise radiation having a frequency selected from the range of 1 - 500 kHz.

[0101] Furthermore, in embodiments, the system may comprise a stem mount configured for attaching the acoustic radiation device to a stem or branch of the cut plant product, especially to a stem, or especially to a branch. Especially, in embodiments, the operational mode may comprise providing acoustic excitation radiation to the stem and detecting acoustic emission radiation from the stem. The stem mount may for example comprise one or more of a clamp, a spring, a male-female type mount, a screw mount, etc... The stem mount may especially be configured to attach the acoustic radiation device to the stem of a cut plant product, such that the acoustic radiation device may be configured both upstream and downstream (with relation to ultrasound waves) of the stem.

[0102] The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of sound from a sound generating means (here especially the acoustic radiation device), wherein relative to a first position within a sound path from the sound generating means, a second position in the sound path closer to the sound generating means is “upstream”, and a third position within the sound path further away from the sound generating means is “downstream”.

[0103] In further embodiments, the system may further comprise a measurement site configured for hosting the cut plant product, wherein the acoustic radiation device comprises an axial radiation detection device arranged at a first location (in the measurement site) arranged axially along the longitudinal axis (of the cut plant product; see above); and / or wherein the acoustic radiation device comprises an axial radiation detection device arranged at a second location (in the measurement site) arranged perpendicular to the longitudinal axis (of the cut plant product).

[0104] In specific embodiments, (i) the cut plant product may comprise a cut Chrysanthemum flower, (ii) the cooling temperature (Tc) may be selected from the range of 1- 6 °C, and (iii) the cooling duration may be selected from the range of 1-3 weeks.

[0105] As mentioned above, the embodiments described herein are not limited to a single aspect of the invention. For example, an embodiment describing the method may, for example, further relate to the system, especially to an operational mode of the system, or especially to the control system. Similarly, an embodiment of the system describing an operation of the system may further relate to embodiments of the method. In particular, an embodiment of the method describing an operation (of the system) may indicate that the system may, in embodiments, be configured for and / or be suitable for the operation. Similarly, an embodiment of the system describing actions of (a stage in) an operational mode may indicate that the method may, in embodiments, comprise those actions.

[0106] BRIEF DESCRIPTION OF THE DRAWINGS

[0107] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: Fig. l schematically depicts embodiments of the method and system of the invention. Figs. 2A-B schematically depict experimental observations obtained using the method of the invention. The schematic drawings are not necessarily on scale.

[0108] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0109] Fig. 1 schematically depicts the method of the invention for estimating a vaselife of a cut plant product 1. In embodiments, the cut plant product 1 may be selected from the group comprising a cut flower and cut foliage. Especially, the cut plant product 1 may comprise a cut stem of a flower selected from the group comprising a Chrysanthemum flower, a Rosa flower, a Gerbera flower, a Hydrangea flower, a Carnation flower, an Anthurium flower, a Tulipa flower, an Orchid flower, a Gladiolus flower, a Lilium flower, a Heliconia flower, a Narcissus flower, a Strelitzia flower and an Alstroemeria flower. Alternatively, the cut plant product 1 may comprise a cut stem of foliage selected from the group comprising and Acacia and a Dracaena.

[0110] As depicted in subfigure I a plant 10 may be grown, which may be used as one of a (target) plant 11 and a reference plant 12. The plant 10 may be harvested (or cut) using a harvesting tool 20, as depicted in subfigure II, to obtain a cut plant product 1, as depicted in subfigure III.

[0111] Subfigure IV-VI schematically depict embodiments of the method for estimating a vase-life of a cut plant product 1. In embodiments, the method may comprise a cooling stage (subfigure IV) comprising subjecting the cut plant product 1 to a cooling temperature (Tc) for a cooling duration (tc). In further embodiments, the cooling temperature (Tc) may be selected from the range of 0 - 10 °C. Further, in embodiments, the cooling duration (tc) may be selected from the range of 0.5 - 4 weeks. In specific embodiments, the cooling temperature (Tc) may be selected from the range of 1-6 °C, whereas the cooling duration may be selected from the range of 1-3 weeks.

[0112] Furthermore, in embodiments, the method may comprise a detection stage (subfigure V) comprising detecting acoustic emission radiation 2 from the (cooled) cut plant product 1 and providing an emission-related signal 3. Moreover, in embodiments, the method may comprise an analysis stage (subfigure VI) comprising determining a settling time (is) based on the emission-related signal 3, and determining the vase-life based on the settling time (TS).

[0113] In embodiments, the analysis stage may comprise determining a (xylem) vessel dimension based on the settling time (TS), and determining the vase-life based on the vessel dimension. Furthermore, in embodiments, the analysis stage may further comprise determining one or more parameters selected from the group comprising: a frequency (f), a time of flight (tof), a power spectrum (or “power spectral density”), phase shift ((|>), and an amplitude (A), based on the emission-related signal 3; fitting one or more of the settling time (TS) and the parameter to a model selected from the group comprising a flexural mode model, a breathing mode model, and a radial mode model; and determining the vessel dimension based on the model.

[0114] As also depicted in subfigure V, in embodiments, the method may further comprise an excitation stage comprising providing acoustic excitation radiation 4 to the cut plant product 1. In embodiments, the acoustic excitation radiation 4 may comprise radiation having a frequency selected from the range of 1 - 500 kHz. Especially, in embodiments, the acoustic excitation radiation 4 may comprise broadband radiation having one or more frequencies in the range of 10 - 150 kHz.

[0115] Furthermore, in embodiments, the excitation stage may comprise providing the acoustic excitation radiation 4 for an excitation duration (te). Especially, in embodiments, the acoustic excitation radiation 4 may be provided via one of a pulse, a wavelet, and a continuous wave. In embodiments, the acoustic excitation radiation 4 may have a characteristic settling time (due to damping) in (a vascular tissue of the) cut plant product 1, wherein the excitation duration (te) may be larger than the characteristic settling time.

[0116] Alternatively, in embodiments, the excitation stage may comprise providing the acoustic excitation radiation 4 for an excitation duration (te). In further embodiments, the excitation duration (te) may be smaller than a time-of-flight of the acoustic excitation radiation 4 through (a vascular tissue of) the cut plant product 1.

[0117] Furthermore, in embodiments, the excitation duration (te) may be selected from the range of 4 ps - 50 ms.

[0118] In embodiments, the excitation stage may comprise an excitation frequency sweep from a first frequency to a second frequency. Additionally or alternatively, in embodiments, the detection stage may comprise an emission frequency sweep from the first frequency to the second frequency;

[0119] Further, in embodiments, the first frequency and the second frequency may be selected from the range of 1-250 kHz.

[0120] In reference to subfigure VII, the invention may further provide a prediction method for providing a predicted vase-life of a (target) plant 11 prior to harvesting the (target) plant 11. In further embodiments, the prediction method may comprise harvesting a reference plant product 12 to provide a cut plant product 1. Further, in embodiments, the plant 11 and the reference plant product 12 may be grown under similar conditions. The prediction method may especially comprise subjecting the cut plant product 1 to the method as described above to provide a vase-life estimate for the reference plant product 12. In embodiments, the prediction method may further comprise predicting the vase-life of the plant 11 based on the vase-life estimate for the reference plant product 12.

[0121] Subfigures IV-V schematically depict a system 100 for estimating a vase-life of a cut plant product 1. Especially, the cut plant product 1 may be selected from the group comprising a cut flower and cut foliage. Further, in embodiments, the system 100 may comprise a cooling arrangement 60, an acoustic radiation device 70 and a control system 30. Especially, the system 100 may have an operational mode. In embodiments, the operational mode may comprise a cooling stage, a detection stage and an analysis stage. Especially, in the cooling stage the cooling arrangement 60 (such as e.g. a cooling truck 50 as depicted in subfigure IV) may be configured to subject the cut plant product 1 to the cooling temperature (Tc) for the cooling duration (tc). Furthermore, in embodiments, in the detection stage the acoustic radiation device 70 may be configured to detect acoustic emission radiation 2 from the (cooled) cut plant product 1 and to provide an emission-related signal 3 to the control system 30.

[0122] Further, in embodiments, in the analysis stage the control system 30 may be configured to determine a settling time (TS) based on the emission-related signal 3, and to determine the vase-life based on the settling time (TS). In embodiments, the control system 30 may further be configured to (have the system 100) execute the method or the prediction method as described above.

[0123] Moreover, in embodiments, the operational mode may further comprise the excitation stage, as described above. Especially, in embodiments, in the excitation stage the acoustic radiation device 70 may be configured to provide acoustic excitation radiation 4 to the cut plant product 1.

[0124] In further embodiments, the system may comprise a stem mount configured for attaching the acoustic radiation device 70 to a stem 15 of the cut plant product 1. In further embodiments, the operational mode may comprise providing acoustic excitation radiation 4 to the stem 15 and detecting acoustic emission radiation 2 from the stem 15.

[0125] In a specific example, in embodiments, the cut plant product 1 may comprise a cut Chrysanthemum flower, the cooling temperature (Tc) may be selected from the range of 1- 6 °C, and the cooling duration may be selected from the range of 1-3 weeks.

[0126] Experiments Plant material and growth conditions - Rooted cuttings of six Chrysanthemum cultivars (Baltica, Fortune, Midnightsun, Radost, Serenity, and Zembla), each displaying six to seven leaves and an average height of 9-10 cm, were transplanted into a greenhouse at Deliflor Chrysanten in Maasdijk, Netherlands. Two distinct plant densities (54 plants / m2, i.e. standard winter conditions, and 74 plants / m2, i.e., summer conditions) and two lighting treatments (LED and Hybrid) were implemented, creating four unique environmental combinations, each replicated twice within the greenhouse setting. The irrigation regimen was maintained at intervals of 2 to 3 days, employing a nutrient solution with an electrical conductivity (EC) of 2.7 dS / m and a pH of 5.6. An overview of the used Chrysanthemum cultivars is provided in table 1 :

[0127] The external references correspond to VBN group codes (or ‘product codes’) as used by the association of flower auctions in the Netherlands (“Vereniging van Bloemenveilingen in Nederland”; www.vbn.nl).

[0128] To stimulate plant growth, carbon dioxide (CO2) supplementation was ranged from 800 to 1200 ppm, with set-points dynamically adjusted in response to ambient changes in growth conditions. During Long-day (LD) photoperiods (see below), air temperatures were maintained at an average of 20.7 °C ± 2.2 for the Hybrid lighting treatment and 20.3 °C ±2.1 for the LED lighting treatment. In contrast, during short-day (SD) photoperiods (see below), the temperatures were moderated to 18.60± 1.6 and 18.4 °C ± 1.6 for the Hybrid and LED lighting treatments, respectively. Relative humidity levels were consistently maintained within the range of 80-85% throughout the experimental period. Lighting conditions - The greenhouse, comprising bays each measuring 30 m in length and 10 m in width, was subjected to distinct lighting treatments (Hybrid lighting and LED lighting) alongside natural sunlight. These treatments were integrated to complement the sunlight, providing suitable light exposure for plant growth and development. One bay was subjected to a Hybrid lighting treatment, utilizing 12 lamps arranged above each planted bed. This set-up included six High-Pressure Sodium (HPS) lamps and six Light Emitting Diode (LED) Lamps, both supplied by Signify, the Netherlands. In contrast, another bay received exclusive LED treatment, featuring 12 identical LED lamps positioned similarly above each bed. The spectral range for the Hybrid lighting (HPS+LEDs) spanned from 400-800 nm, whereas the LED-only lighting covered a range from 400-700 nm. Precise light measurements were undertaken per experimental unit at the plant canopy level using a spectrometer (Specbos 1211, Jeti Technische Instrumente GmbH, Jena, Germany).

[0129] Alongside the natural sunlight in the greenhouse, lighting treatments were administered for 20 hours daily during a 15-day long-day (LD) period. Subsequently, during a short-day (SD) period, the lamps were activated for 12 hours daily. To compensate for a low Daily Light Integral (DLI) observed during the experiment, both lighting setups were kept continuously active to facilitate a suitable comparison of the light treatments in terms of their impact on plant growth and morphology. In addition to the natural sunlight intensity (measured in W / m2) in the greenhouse, the estimated average proportion of Photosynthetically Active Radiation (PAR) from supplemental lighting in relation to sunlight was approximately 40% (±12%) during the LD period and 45% (±9%) during the SD period for both lighting treatments. Opaque vertical screens were fully closed along the edges of each bay throughout the entire day for the initial seven days of the LD period. Subsequently, these screens were partially closed during the photoperiod (from 07.00 h to 16.00) and fully closed during the night (from 16.00 h to 07.00 h) to prevent light pollution from adjacent bays. During the SD period, the bays were completely darkened from the start of the night (following 12 hours of lighting) to prevent light leakage from bays cultivated under LD conditions.

[0130] Vase-life tests - The harvested Chrysanthemum cut flower stems, organized into bunches of five and enclosed in plastic sleeves, were subjected to cold storage at 3 °C for two weeks to simulate a cold chain transit. Following this period, the stems were divided into two groups: Group 1 for prior art vase life measurements and Group 2 for ultrasound pulse measurements as the non-destructive characterization method of the invention.

[0131] Prior art methods: Stems from Group 1 were carefully extracted from the plastic sleeves, uniformly trimmed to a standard length of 60 cm, and placed in glass vases (of 1.5 liter) filled with clean distilled water to maintain their hydration and vitality. Throughout the subsequent two-week monitoring period, the Chrysanthemum stems in the vases underwent systematic monitoring, which included visual inspections and measurements of relevant quality parameters such as transpiration rate, wilting, yellowing and browning of leaves, and flower components like ray and disc florets. These assessments were specifically designed to evaluate the overall post-harvest performance of the cut Chrysanthemum stems. Vase life was measured in days and was calculated based on the wilting, yellowing and browning, i.e., defined by the duration that the cut flowers maintained their aesthetic appeal post-harvest. The vase life evaluation period concluded when leaves began to yellow of when approximately 10% of the flowers exhibited wilting and petal drop.

[0132] Ultrasound stem characterization: Group 2 stems were carefully extracted from the plastic sleeves, uniformly trimmed to a standard length of 60 cm, and placed in glass vases filled with clean distilled water for 10 minutes to maintain their hydration and vitality. Immediately thereafter, a flower was removed from its vase, the cut-end dried using tissue paper, and placed on a bench for air drying, inducing accelerated drought stress. An M500- USB ultrasound microphone from Pettersson Elektronik AB (Uppsala, Sweden), with a detection window ranging from 10-250 kHz was employed. Positioned axially approximately 1 mm from the cut-face of the stem, perpendicular to the cross-section, the microphone recorded ultrasound bursts at a sampling rate of 500 kHz over a continuous duration of approximately 100 seconds at room temperature (20 °C). The influence of background noise and spurious signals was minimized by setting a pulse detection threshold of 0.005 a.u. at the microphone output. A time-domain signal was obtained, in which each individual ultrasound emission appeared as a distinct peak. For each individual peak the pulse envelope was obtained with the built-in “envelope ()”-function in MATLAB, which returns the upper and lower envelopes of the input sequence. The peak of the envelope curve was determined, and the decreasing part of the envelope curve was stored and subsequently fitted with the exponential function using the least squares method, where the variable t denotes time. This yielded the settling time (is). wherein Ao is the amplitude at the peak of the pulse (here at about T=0.3s).

[0133] Optical xylem vessel diameter - From all stems utilized in the ultrasound characterization, one representative from each set of five was selected. The stems were sliced with a razorblade to 5 mm and the cut stems were placed under a VHX digital microscope from Keyence. The xylem vessel diameter was determined from the obtained images by converting them to a grayscale image and utilizing the built-in “imfindcircles ()”-function in MATLAB with a lower radius threshold of 7 gm and an upper threshold of 100 pm. From the calculated radii, a histogram was generated and a log-normal distribution fit using the least squares method to identify the most probable radius (namely the peak of the log-normal probability density function) was applied.

[0134] Acoustic radius - In order to gain insight into the settling time (is), derived from the acoustic pulses under different growing conditions, the data was categorized by each cultivar and condition into respective histograms. By applying a log-normal distribution fit to the histogram data, it was determined that the most probable settling time for the lower planting density of 54 / m2was 24.2 ps, while for the higher density it was 28.6 ps. The obtained settling times were converted into acoustic radii (ra), utilizing the methodology outlined in DUTTA et al ., “ Ultrasound Pulse Emission Spectroscopy Method to Characterize Xylem Conduits in Plant Stems’", Research, Volume 2022, which is herein hereby incorporated by reference. In particular, the acoustic radii (ra) were determined according to: ra = 74?ITS / P wherein q is the viscosity of the water inside the xylem vessels determined at q =8.9* 10'4Pa*s and p is the density of the water inside the xylem vessels, which was determined to be 996 kg / m3, i.e., p = 996 kg / m3. The relationship between the acoustic radius and the density and viscosity as described in the above formula was derived by modelling the vessel element as a cylindrical acoustic resonator (organ pipe). The result indicated that for Baltica and hybrid lighting conditions, the acoustic radius for 54 / m2is 10.2 pm and for 74 / m2is 10.7 pm. Further analysis of other varieties also led to small differences in rafor high and low planting density. For Baltica and Zembla, rais lower for lower planting density, whereas it is higher for Fortune and Radost. Midnight and Serenity almost show no difference in rafor low and high planting density. Similar results were found for the LED lighting condition. These findings suggest that the relation between raand planting density varies depending on the specific Chrysanthemum cultivar.

[0135] Optical radius - To validate the acoustic radii obtained, optical microscopy was conducted on stem cross-sections. The data was fitted in histograms to a log-normal distribution to obtain the most probable r0. The histograms showed that the r0approximates 10 pm showing consistency across different cultivars.

[0136] Correlation of radii with vase-life - The relationship between the radii measurements, both optical (r0) and acoustic (ra) radii, and the vase-life outcomes across different Chrysanthemum cultivars under varied conditions was investigated. Figs. 2A-B indicate the vase-life V (in days), the determined acoustic radius ra(in pm), the determined optical radius r0(in pm). Specifically Fig. 2A indicates the vase-life V against the determined acoustic radius ra, whereas Fig. 2B indicates the vase-life V against the determined optical radius r0. Fig. 2 depicts the result from the following six cultivars: Baltica - (I) & (VII); Fortune - (II) & (VIII); Midnightsun (III) & (IX); Radost - (IV) & (X); Serenity - (V) & (XI); and Zembla - (VI) & (XII). The vase-life exhibited considerable variability, ranging from 9 to 14.5 days, and correlated significantly with both radii metrics. Specifically, the acoustic radius (ra) was observed to positively correlate with extended vase-life (up to 14.5 days) in the cultivars Fortune (R=0.74), Radost (R=0.53), and Zembla (R=0.56), see Fig. 2A subfigures II, IV, and VI, respectively. Conversely, a negative correlation of the acoustic radius rawith reduced vaselife (up to 12.5 days) was observed in the cultivars Baltica (R=-0.97), Midnightsun (R=-0.82) and Serenity (R=-0.42), see Fig. 2A subfigures I, III and V, respectively.

[0137] The optical radius (r0) also positively correlated with extended vase-life in the cultivars Fortune (R=0.90), Radost (R=0.57), and Zembla (R=0.78), see Fig. 2B subfigures VIII, X, and XII, respectively, mirroring the trends observed in acoustic measurements but with varying intensities and patterns among cultivars. However, no significant (i.e. |R[<0.5) correlations were found in cultivars for which a negative association between vase-life and acoustic radius rawas observed, suggesting a cultivar-specific response to physiological changes as measured by optical properties, see Fig. 2B subfigures VII and IX, respectively.

[0138] The data depicted in Figs. 2A and 2B correspond to experiments performed using the method of the invention, i.e., including a cooling step. The same experiments were performed without the use of a cooling step. Although similar correlations of vase-life V against acoustic radius rato the above described were observed for the cultivars Fortune and Radost, with respectively R=0.75 and R=0.65, no significant correlations (i.e. |R[<0.5) were observed for the other cultivars: R=0.20 (for Baltica), R=0.00 (for Midnightsun), R=0.07 (for Serenity), and R=0.26 (for Zembla). These results demonstrate that the cooling step substantially contributes to a consistent performance in vase life estimation of cut plant products.

[0139] In Figs. 2A and 2B, the data are visualized using linear regression models (indicated by the dashed lines), employed to calculate the Pearson correlation coefficients for each relationship. The different growing conditions are distinguished using: triangles for representing 54 / m2under LED lighting, diamonds for representing 54 / m2under hybrid lighting, squares for representing 74 / m2under LED lighting, and circles for representing 74 / m2under hybrid lighting. The findings, depicted in Figs. 2A and 2B, highlight the complex interplay between physical vessel attributes and floral longevity. Notably, the correlation of vase-life with acoustic radius (ra) highlights the potential of using the acoustic radii measurements as a novel, non-invasive method to predict the longevity of cut flowers postharvest.

[0140] The term “plurality” refers to two or more. Furthermore, the terms “a plurality of’ and “a number of’ may be used interchangeably.

[0141] The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. Moreover, the terms ’’about” and “approximately” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90% - 110%, such as 95%-105%, especially 99%-101% of the values(s) it refers to.

[0142] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

[0143] The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of' but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

[0144] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0145] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0146] The term “further embodiment” and similar terms may refer to an embodiment comprising the features of the previously discussed embodiment, but may also refer to an alternative embodiment. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0147] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0148] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, “include”, “including”, “contain”, “containing” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0149] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0150] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0151] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. Moreover, if a method or an embodiment of the method is described being executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suitable for or configured for (executing) the method or the embodiment of the method, respectively.

[0152] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A method for estimating a vase-life of a cut plant product (1), wherein the cut plant product (1) is selected from the group comprising a cut flower and cut foliage, wherein the method comprises: a cooling stage comprising subjecting the cut plant product (1) to a cooling temperature (Tc) for a cooling duration (tc), wherein the cooling temperature (Tc) is selected from the range of 0 - 10 °C, and wherein the cooling duration (tc) is selected from the range of 0.5 - 4 weeks; a detection stage comprising detecting acoustic emission radiation (2) from the cut plant product (1) and providing an emission-related signal (3); and an analysis stage comprising determining a settling time (is) based on the emission-related signal (3), and determining the vase-life based on the settling time (TS).

2. The method according to claim 1, wherein the analysis stage comprises determining a vessel dimension based on the settling time (TS), and determining the vase-life based on the vessel dimension.

3. The method according to claim 2, wherein the analysis stage further comprises determining a parameter selected from the group comprising: a frequency (f), a time of flight (tof), and an amplitude (A), based on the emission-related signal (3), and wherein the method further comprises: fitting one or more of the settling time (TS) and the parameter to a model selected from the group comprising a flexural mode model, a breathing mode model, and a radial mode model, and wherein the method comprises determining the vessel dimension based on the model.

4. The method according to any one of the preceding claims, wherein the method further comprises an excitation stage comprising providing acoustic excitation radiation (4) to the cut plant product (1), wherein the acoustic excitation radiation (4) comprises radiation having a frequency selected from the range of 1 - 500 kHz.

5. The method according to claim 4, wherein the acoustic excitation radiation (4) comprises broadband radiation having one or more frequencies in the range of 10 - 150 kHz.

6. The method according to any one of the preceding claims 4-5, wherein the excitation stage comprises providing the acoustic excitation radiation (4) for an excitation duration (te), wherein the acoustic excitation radiation (4) has a characteristic settling time in the cut plant product (1), wherein the excitation duration (te) is larger than the characteristic settling time (is).

7. The method according to any one of the preceding claims 4-5, wherein the excitation stage comprises providing the acoustic excitation radiation (4) for an excitation duration (te), wherein the excitation duration (te) is smaller than a time-of-flight of the acoustic excitation radiation (4) through the cut plant product (1).

8. The method according to any one of the preceding claims 4-7, wherein one or more applies of: the excitation stage comprises an excitation frequency sweep from a first frequency to a second frequency; and the detection stage comprises an emission frequency sweep from the first frequency to the second frequency; wherein the first frequency and the second frequency are selected from the range of 1-250 kHz.

9. The method according to any one of the preceding claims, wherein the cut plant product (1) comprises a cut stem of a flower or foliage selected from the group comprising a Chrysanthemum flower, a Rosa flower, a Gerbera flower, a Hydrangea flower, a Carnation flower, an Anthurium flower, a Tulipa flower, an Orchid flower, a Gladiolus flower, a Lilium flower, a Heliconia flower, a Narcissus flower, a Strelitzia flower, an Alstroemeria flower, an Acacia, and a Dracaena.

10. The method according to any one of the preceding claims, wherein the cooling temperature (Tc) is selected from the range of 1-6 °C, and wherein the cooling duration is selected from the range of 1-3 weeks.

11. A prediction method for providing a predicted vase-life of a plant (11) prior to harvesting the plant (11), wherein the prediction method comprises harvesting a reference plant product (12) to provide a cut plant product (1), wherein the plant (11) and the reference plant product (12) are grown under similar conditions, wherein the prediction method comprises subjecting the cut plant product (1) to the method according to any one of the preceding claims to provide a vase-life estimate for the reference plant product (12), and wherein the prediction method further comprises predicting the vase-life of the plant (11) based on the vase-life estimate for the reference plant product (12).

12. A system (100) for estimating a vase-life of a cut plant product (1), wherein the cut plant product (1) is selected from the group comprising a cut flower and cut foliage, wherein the system (100) comprises a cooling arrangement (60), an acoustic radiation device (70) and a control system (30), wherein the system (100) has an operational mode, wherein the operational mode comprises a cooling stage, a detection stage and an analysis stage, wherein: in the cooling stage the cooling arrangement (60) is configured to subject the cut plant product (1) to a cooling temperature (Tc) for a cooling duration (tc), wherein the cooling temperature (Tc) is selected from the range of 0 - 10 °C, and wherein the cooling duration (tc) is selected from the range of 0.5 - 4 weeks; in the detection stage the acoustic radiation device (70) is configured to detect acoustic emission radiation (2) from the cut plant product (1) and to provide an emission-related signal (3) to the control system (30); and in the analysis stage the control system (30) is configured to determine a settling time (TS) based on the emission-related signal (3), and to determine the vase-life based on the settling time (TS).

13. The system (100) according to claim 12, wherein the operational mode further comprises an excitation stage, wherein in the excitation stage the acoustic radiation device (70) is configured to provide acoustic excitation radiation (4) to the cut plant product (1), wherein the acoustic excitation radiation (4) comprises radiation having a frequency selected from the range of 1 - 500 kHz.

14. The system (100) according to claim 13, wherein the system comprises a stem mount configured for attaching the acoustic radiation device (70) to a stem (15) of the cut plantproduct (1), wherein the operational mode comprises providing acoustic excitation radiation (4) to the stem (15) and detecting acoustic emission radiation (2) from the stem (15).

15. The system (100) according to any one of the preceding claims 12-14, wherein the cut plant product (1) comprises a cut Chrysanthemum flower, and wherein the cooling temperature (Tc) is selected from the range of 1-6 °C, and wherein the cooling duration (tc) is selected from the range of 1-3 weeks.

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