Method for comparing cold resistance of fruit tree dormant branches

Abstract

The application provides a fruit tree dormant branch cold resistance comparison method, relates to the technical field of fruit tree cultivation, and comprises the following steps: alternately performing polarization mode operation and impedance mode operation on the same detection site of the fruit tree dormant branch; when the polarization mode operation is performed, first wave band laser and second wave band laser are emitted to the detection site at a preset incident angle, and a transmitted light intensity data group is obtained; when the impedance mode operation is performed, a sweep frequency current is injected into the detection site, and an impedance component data group of a characteristic frequency point is collected; the intercellular ice crystal density is calculated according to the transmitted light intensity data group; the membrane lipid phase shift angle is calculated according to the impedance component data group; when the intercellular ice crystal density is greater than an activation threshold value, the ice crystal-membrane lipid synergy ratio is calculated based on the intercellular ice crystal density and the membrane lipid phase shift angle; the cold resistance synergy index is calculated according to the change rate of the intercellular ice crystal density and the membrane lipid phase shift angle; and the cold resistance grade is determined according to the cold resistance synergy index value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fruit tree cultivation, in particular to a method for comparing cold resistance of dormant branches of fruit trees. BACKGROUND

[0002] The cold resistance of fruit trees is a key trait affecting the distribution, yield and overwintering survival of fruit trees. Accurate evaluation of the cold resistance of dormant branches of fruit trees is of great significance for variety breeding, planting area planning and cold protection measures.

[0003] Current detection of the cold resistance of dormant branches of fruit trees mainly relies on the in vitro freezing method (such as the electrolyte exudation rate method), which requires cutting branches, resulting in three distortions: ① interruption of water / nutrient supply in pruning, imbalance of cell osmotic pressure; ② ABA surge and callose deposition induced by wound response; ③ hormone regulation network separated from the plant. Existing non-destructive techniques (such as near-infrared spectroscopy) can only indirectly evaluate the cold resistance through water content, and cannot quantify the synergistic process of ice crystal growth and membrane lipid damage.

[0004] Based on this, the present application provides a method for comparing the cold resistance of dormant branches of fruit trees. SUMMARY

[0005] The present application provides a method for comparing the cold resistance of dormant branches of fruit trees to solve the above technical problems.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A method for comparing the cold resistance of dormant branches of fruit trees, comprising the following steps:

[0008] Alternately performing polarization mode operation and impedance mode operation on the same detection site of the dormant branches of the fruit trees; wherein, when performing the polarization mode operation, emitting first waveband laser and second waveband laser at a preset incident angle to the detection site, and collecting a transmitted light intensity data set; when performing the impedance mode operation, injecting a sweep frequency current to the detection site, and collecting an impedance component data set of a characteristic frequency point;

[0009] Calculating the ice crystal density in the intercellular space according to the transmitted light intensity data set;

[0010] Calculating the membrane lipid phase shift angle according to the impedance component data set;

[0011] When the ice crystal density in the intercellular space is greater than an activation threshold, calculating the ice crystal-membrane lipid synergistic ratio based on the ice crystal density in the intercellular space and the membrane lipid phase shift angle;

[0012] Calculating the cold resistance synergistic index according to the change rate of the ice crystal density in the intercellular space and the membrane lipid phase shift angle;

[0013] Determining the cold resistance grade according to the cold resistance synergistic index value.

[0014] Further, the expression of the transmitted light intensity data set is: , wherein, represents the first waveband laser incident light intensity original value; represents the first waveband laser transmitted light intensity real-time value; represents the second waveband laser incident light intensity original value; represents the second waveband laser transmitted light intensity real-time value;

[0015] The calculation formula of the cell gap ice crystal density is:

[0016]

[0017] , wherein, represents the cell gap ice crystal density; represents the tree optical constant; represents the temperature compensation coefficient; represents the branch surface real-time temperature; represents the tissue freezing point temperature; represents the water correction factor.

[0018] Further, the expression of the impedance component data set is:

[0019] The calculation formula of the membrane lipid phase shift angle is:

[0020]

[0021] , wherein, represents the membrane lipid phase shift angle; represents the impedance real part; represents the impedance imaginary part.

[0022] Further, in the impedance mode operation, the selection method of the characteristic frequency point is:

[0023] The target fruit tree variety is swept from 10 kHz to 10 MHz full frequency band;

[0024] The frequency point with the maximum change rate of complex impedance phase angle is selected as the characteristic frequency point The expression of the characteristic frequency point is:

[0025]

[0026] , wherein, , represents the complex impedance phase angle; represents the change rate of the complex impedance phase angle with the sweep current frequency.

[0027] ​Further, the calculation formula of the ice crystal-membrane lipid synergistic ratio is:

[0028]

[0029] In the formula, represents the ice crystal-membrane lipid synergistic ratio; represents the ice crystal growth rate coefficient; represents the membrane lipid critical phase shift angle; represents the synergistic shape factor; represents the maximum tolerable intercellular ice crystal density of the tree species; represents the relative degree of ice crystal accumulation;

[0030] When , it is forced that =1.

[0031] Further, the calculation formula of the intercellular ice crystal density and the membrane lipid phase shift angle change rate is:

[0032]

[0033]

[0034] In the formula, and are two adjacent data acquisition time points; represents the intercellular ice crystal density change rate; and are the intercellular ice crystal densities at time points and , respectively;

[0035] represents the membrane lipid phase shift angle change rate; and are the membrane lipid phase shift angles at time points and , respectively, which are synchronously collected with and .

[0036] The calculation formula of the cold resistance synergistic index is:

[0037]

[0038] In the formula, represents the cold resistance synergistic index; represents the time difference attenuation coefficient; represents the switching time interval of the polarization mode operation and the impedance mode operation, wherein , is the ice crystal nucleation period.

[0039] Further, when , a high cold resistance identifier is outputted, wherein, represents a high cold resistance threshold value; when D2 , a medium cold resistance identifier is outputted; when , a low cold resistance identifier is outputted, wherein, represents a low cold resistance threshold value.

[0040] Advantages of the present application:

[0041] (1) Combining the polarization laser transmission technology (representing the ice crystal density of cell gap) and impedance spectrum analysis (representing the phase shift angle of membrane lipid), the cold resistance characteristics are quantified from the optical and electrical dimensions, avoiding the limitation of single index, and the detection result is more in line with the actual cold resistance physiological state of dormant branches.

[0042] (2) By alternately collecting real-time data in different modes, the change rate of ice crystal density and membrane lipid phase shift angle is calculated, the dynamic change of cold resistance characteristics in the process of low temperature stress is realized, and the static evaluation is not realized, which can better reflect the cold resistance response of fruit tree dormant branches in the real low temperature environment.

[0043] (3) The "ice crystal-membrane lipid synergistic ratio" and "cold resistance synergistic index" are introduced to quantify the synergistic mechanism of ice crystal growth and membrane lipid damage, break through the surface analysis of traditional method only through single physiological index (such as conductivity, survival rate) to determine the cold resistance, and reveal the essence of cold resistance from the molecular level.

[0044] (4) During the detection process, the structure of the dormant branch is not damaged, and only through laser transmission and current injection detection, the same sample can be continuously monitored, the data acquisition is efficient and the synchronization is strong. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The flow chart of the fruit tree dormant branch cold resistance comparison method of the embodiment of the present application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0047] As shown in Figure 1 , a fruit tree dormant branch cold resistance comparison method of the embodiment of the present application comprises the following steps:

[0048] S1: alternately performing a polarization mode operation and an impedance mode operation on the same detection site of the fruit tree dormant branch; wherein, when the polarization mode operation is performed, a first wave band laser and a second wave band laser are emitted to the detection site at a preset incident angle, and a transmission light intensity data set is obtained by collection; when the impedance mode operation is performed, a sweep frequency current is injected into the detection site, and an impedance component data set of a characteristic frequency point is collected.

[0049] The step synchronously acquires original data reflecting the ice crystal state of the cell gap and the characteristics of the cell membrane lipid by alternately performing the polarization mode operation and the impedance mode operation on the same detection site of the fruit tree dormant branch, so as to realize multi-dimensional and real-time monitoring of the cold resistance related physiological indexes of the dormant branch. Specifically, by synchronously collecting the multi-physical field (optical, electrical) signals, the real-time monitoring of the ice crystal state of the cell gap (optical signal) and the state of the cell membrane lipid (electrical signal) of the fruit tree dormant branch is realized, which provides original data for subsequent calculation of the cell gap ice crystal density, the membrane lipid phase shift angle and the cold resistance synergy index.

[0050] It should be noted that the selected fruit tree dormant branch is a fruit tree branch (such as 1-2 year old branches of apple, pear, peach and the like) in a natural dormancy or artificially induced dormancy state. For the detection site, a smooth part without damage and branch in the middle of the branch is selected to ensure that the same detection site remains consistent in the polarization mode and impedance mode operations (which can be realized by marking or fixing the detection probe), so as to avoid data deviation caused by site difference.

[0051] The polarization mode operation can obtain the optical characteristics of the ice crystal of the cell gap through laser transmission technology. For example, two specific wave band lasers are emitted to the detection site at a preset incident angle of 0°-45°, wherein the incident angle can be adjusted according to the diameter and surface curvature of the branch. In addition, the wavelength of the first wave band laser is 905±5nm (near-infrared wave band), which is sensitive to the scattering effect of ice crystal particles and can effectively reflect the number and distribution of ice crystals; and the wavelength of the second wave band laser is 1450±10nm (mid-infrared wave band), which has a significant water absorption effect and can be used to correct the interference of the water content in the cell on the ice crystal detection.

[0052] The ice crystal formed in the cell gap will cause scattering effect on the laser, resulting in weakening of the transmission light intensity, and the higher the ice crystal density, the stronger the scattering effect, and the more obvious the attenuation of the transmission light intensity. By comparing the transmission light intensity changes of the two wave bands, the influence of ice crystal scattering and water absorption can be distinguished, and the accuracy of the calculation of the ice crystal density can be improved.

[0053] In the present application, the incident light intensity original value and the transmission light intensity real-time value of the two wave band lasers are synchronously collected to form a transmission light intensity data set and an impedance component data set Specifically, the expression of the transmitted light intensity data set is: , wherein, represents the first waveband laser incident light intensity original value (i.e. the incident light intensity original value of the first waveband laser when the branch is not irradiated, which is the reference value); represents the first waveband laser transmitted light intensity real-time value (the transmitted light intensity real-time value of the first waveband laser after passing through the branch (light intensity after ice crystal scattering attenuation)); represents the second waveband laser incident light intensity original value (i.e. the incident light intensity original value of the second waveband laser when the branch is not irradiated, which is the reference value); represents the second waveband laser transmitted light intensity real-time value (the transmitted light intensity real-time value of the second waveband laser after passing through the branch (light intensity after water absorption attenuation)).

[0054] It should be understood that the electrical characteristics (resistance and capacitance) of the cell membrane depend on the arrangement state and integrity of the membrane lipid: when the membrane lipid is orderly arranged (cold resistance state), the capacitance is stable and the resistance is high; when the membrane lipid undergoes phase transition (frozen damage), the membrane structure is loose, and the capacitance and resistance change abruptly. By monitoring the impedance change of the characteristic frequency point, the state change of the membrane lipid can be captured in real time.

[0055] Therefore, in the present application, the impedance mode operation obtains the electrical characteristics of the cell membrane lipid by sweep current injection technology. For example, a sweep current (alternating current, the amplitude is usually 10-50 μA, which avoids damaging the cell) with a frequency range of 10 kHz-10 MHz is injected into the detection site, covering the sensitive frequency band of the cell membrane lipid capacitance characteristics and the cell liquid resistance characteristics.

[0056] Specifically, the expression of the impedance component data set is: , wherein, represents the impedance real part (resistance component), which reflects the resistance of ion conduction in the cell liquid, and is related to the integrity of the cell membrane (when the membrane is damaged, ion leakage leads to decrease). represents the impedance imaginary part (capacitance component), which reflects the capacitance characteristics of the double-layer structure of the cell membrane, and is related to the fluidity of the membrane lipid (when the membrane lipid undergoes phase transition, significant change).

[0057] In the impedance mode operation, in order to improve the sensitivity of the membrane lipid state detection, a characteristic frequency point needs to be selected from the 10 kHz-10 MHz frequency band. The selection method of the characteristic frequency point is:

[0058] S11: sweep frequency of 10 kHz-10 MHz for the target fruit tree variety;

[0059] S12: Select the frequency point with the largest phase angle change rate of complex impedance as the characteristic frequency point .

[0060] Characteristic frequency point The expression is:

[0061] , wherein ,

[0062] In the formula, represents the phase angle of complex impedance, which reflects the phase relationship between the imaginary part and the real part of impedance, and is directly related to the electrical properties of membrane lipids. represents the rate of change of the phase angle of complex impedance with the frequency of the sweep current, and the frequency corresponding to the maximum value is the frequency point at which the membrane lipid state changes most sensitively (at this frequency, membrane lipid phase transition or damage will cause significant changes in impedance signals).

[0063] S2: Calculate the ice crystal density in the intercellular space according to the transmitted light intensity data set The parameter directly reflects the degree of freeze damage to the dormant branches of fruit trees.

[0064] Ice crystals in the intercellular space will scatter and reflect incident laser light, causing attenuation of transmitted light intensity. Different wavebands of laser light have different sensitivities to ice crystals and water.

[0065] For example, the first waveband laser ( =905±5nm) is more sensitive to the scattering of ice crystal particles, and its transmitted light intensity attenuation is mainly determined by ice crystal density; the second waveband laser ( =1450±10nm) has more significant absorption of water, which can be used to correct the interference of water content in cells on ice crystal detection. By fusing the transmitted light intensity data of the two wavebands and introducing temperature compensation, the ice crystal density in the intercellular space can be accurately quantified.

[0066] Therefore, the calculation formula of the ice crystal density in the intercellular space is:

[0067]

[0068] The formula includes an ice crystal scattering term , a water correction term , and a temperature compensation term ; wherein the ice crystal scattering term is used to directly relate the scattering of ice crystals on the first waveband laser; the water correction term is used to offset the absorption interference of water in cells on the second waveband laser, to avoid misjudging water as ice crystals; the temperature compensation term is used to correct the influence of volume changes caused by shrinkage of branches at low temperatures or expansion at high temperatures on ice crystal density, to ensure consistency of measurements at different temperatures.

[0069] In the formula, The value represents the density of ice crystals in the intercellular spaces (g / cm³), reflecting the degree of frost damage. The higher the value, the more ice crystals accumulate in the intercellular spaces, and the more severe the frost damage.

[0070] This represents the attenuation coefficient of the first-band laser, reflecting the degree of light intensity attenuation caused by ice crystal scattering. A larger value indicates more ice crystals. This indicates the transmittance of the second-band laser, which mainly reflects the change in light intensity caused by water absorption. The absolute value of the difference between the real-time temperature and the freezing point temperature reflects the degree of low-temperature stress experienced by the branch. The larger the difference, the stronger the driving force for ice crystal formation.

[0071] Represents the optical constant of tree species ( Its properties are determined by the light transmittance of the waxy layer on the surface of the dormant branches of fruit trees, and different tree species... The values ​​are different; for example, apples are approximately 0.025, while peaches are approximately 0.031. Indicates the temperature compensation coefficient ( This is used to correct the error in ice crystal density measurement caused by the thermal expansion of branches due to temperature changes; It indicates the real-time temperature of the branch surface, which can be collected synchronously via a temperature sensor; This indicates the freezing point temperature of the tissue, which is the critical temperature at which the cells of the branch begin to freeze. It is determined by the physiological characteristics of the tree species. For example, apples ≈ -2.5℃ and grapes ≈ -4.3℃. This represents the moisture correction factor, used to correct the absorption interference of intracellular free water on the second-band laser. Its value range is usually 0.01-0.03, and it is adjusted according to the water content of the tree species. For example, for pear tree branches, c is 0.022.

[0072] S3: Calculate the membrane lipid phase shift angle based on the impedance component data set. This parameter is used to characterize the fluidity and phase transition state of cell membrane lipids and is a key indicator reflecting the cold resistance stability of the cell membrane.

[0073] It should be noted that the cell membrane is mainly composed of a lipid bilayer, and its electrical properties can be represented by a "resistance-capacitance" composite model. The ordered arrangement of membrane lipid molecules determines the membrane's capacitance (the imaginary part of the impedance). The conductivity of ions inside and outside the membrane determines the membrane's resistivity (real part of impedance). When the membrane lipid is in a stable state (strong cold resistance), the molecules are arranged in an orderly manner, and the ratio of capacitance to resistance is stable. When the membrane lipid is frozen and undergoes a phase transition (weak cold resistance), the molecular arrangement becomes disordered, and the ratio of capacitance to resistance changes significantly. The state of the membrane lipid can be quantified by calculating the phase relationship (phase shift angle) between the imaginary and real parts of the impedance.

[0074] Specifically, the membrane lipid phase shift angle calculation formula is:

[0075]

[0076] In the formula, represents the membrane lipid phase shift angle, and the value range is usually 0°-90°. The smaller the value (such as <30°), the more closely ordered the membrane lipid molecules, the lower the fluidity, and the more stable the cold resistance state. The larger the value (such as >60°), the more loosely ordered the membrane lipid molecules, the higher the fluidity, and the more damaged the phase change. The imaginary part of impedance reflects the capacitive characteristics (capacitance) of the cell membrane, which is related to the integrity of the membrane lipid bilayer. When the membrane lipid is ordered, the value is larger; when the membrane lipid is disordered, the value is significantly reduced. The real part of impedance reflects the resistive characteristics (resistance) of the cell membrane, which is related to the conduction resistance of ions inside and outside the membrane. When the membrane lipid is complete, it is difficult for ions to penetrate, the value is larger; when the membrane lipid is damaged, the value is significantly reduced. The ratio of the imaginary part to the real part of impedance reflects the balance between the capacitive and resistive properties of the membrane lipid, which is directly related to the order degree of the membrane lipid.

[0077] S4: When the density of ice crystals in the intercellular space is greater than the activation threshold, calculate the ice crystal-membrane lipid synergy ratio based on the density of ice crystals in the intercellular space and the membrane lipid phase shift angle. This parameter is used to quantify the degree of synergy between ice crystal growth and membrane lipid damage.

[0078] When the density of ice crystals is lower than the activation threshold, the number of ice crystals in the intercellular space is small, and the impact on the membrane lipid can be ignored (the membrane lipid is still in a stable state). When the density of ice crystals exceeds the activation threshold, ice crystals begin to exert mechanical pressure or osmotic stress on the cell membrane, and the interaction between the two needs to be evaluated through the synergy ratio. Therefore, the calculation of the ice crystal-membrane lipid synergy ratio is not performed in all cases, and it needs to meet the premise that the density of ice crystals in the intercellular space is greater than the activation threshold. For example, , the specific threshold of different tree species is slightly different (for example, the apple is 0.10 g / cm³, and the peach tree is 0.08 g / cm³).

[0079] Specifically, when the trigger condition is met, the calculation formula of the ice crystal-membrane lipid synergy ratio is:

[0080]

[0081] In the formula, represents the ice crystal-membrane lipid synergy ratio, and the value range is [0, 1]. tends to 0, indicating that there is no synergy between ice crystal growth and membrane lipid damage (the membrane lipid can resist the stress of ice crystals, and the cold resistance ability is strong); Tending to 1 indicates that ice crystal growth is highly synergistic with membrane lipid damage (ice crystals quickly destroy membrane structure, and cold resistance is weak).

[0082] represents the ice crystal growth rate coefficient, which is related to the activity of antifreeze protein, the higher the activity of antifreeze protein, the smaller the value; represents the critical phase shift angle of membrane lipid, the trigger threshold of phase transition of membrane lipid, when , the membrane lipid is in a stable state, and when , the membrane lipid undergoes irreversible phase transition.

[0083] is the difference between the phase shift angle of membrane lipid and the critical value, which represents the "safety margin" of membrane lipid from phase transition, the larger the difference, the more stable the membrane lipid (the stronger the cold resistance potential).

[0084] represents the synergistic shape factor, which reflects the degree of nonlinear coupling between ice crystal growth and membrane lipid damage, the value range is 1.5-3.0, for example, m=2.0 for apple, m=2.5 for pear, the larger the m value, the more intense the response of membrane lipid to ice crystal growth (small increase in ice crystal can cause rapid damage to membrane lipid). represents the maximum tolerable intercellular ice crystal density of the tree species, i.e. the critical value of cell rupture, characterizes the relative degree of ice crystal accumulation (0~1).

[0085] wherein when the phase shift angle of membrane lipid exceeds the critical value, i.e. , it is forced =1, indicating that the membrane system has completely collapsed (the synergistic effect of ice crystal and membrane lipid reaches the maximum, and the cold resistance is lost).

[0086] S5: Calculate the cold resistance synergistic index according to the change rate of intercellular ice crystal density and membrane lipid phase shift angle, which comprehensively reflects the dynamic response relationship between ice crystal growth and membrane lipid damage of the dormant branches of fruit trees under low temperature stress.

[0087] The calculation of the cold resistance synergistic index needs to obtain the change rate of intercellular ice crystal density and the change rate of membrane lipid phase shift angle, both of which are calculated by the difference between the measured data of adjacent time points.

[0088] Specifically, the change rate calculation formula of intercellular ice crystal density and membrane lipid phase shift angle is:

[0089]

[0090]

[0091] In the formula, and are two adjacent data collection time points. represents the rate of change of the ice crystal density in the intercellular space, which reflects the growth speed of the ice crystal in the intercellular space, and the greater the value, the faster the ice crystal accumulates at low temperature, and the higher the potential risk of frost damage to the branch; and are the intercellular ice crystal densities (calculated by step S2) at time points and respectively.

[0092] represents the rate of change of the membrane lipid phase shift angle, which reflects the change speed of the membrane lipid fluidity, and the greater the value, the more likely the membrane lipid undergoes phase transition (from order to disorder) at low temperature, and the poorer the stability of the membrane system; and are the membrane lipid phase shift angles (calculated by step S3) at time points and respectively, which are synchronously collected with and .

[0093] The formula for calculating the cold resistance synergy index is:

[0094]

[0095] In the formula, represents the cold resistance synergy index, the value of which directly reflects the strength of cold resistance, and in which, the greater the value, the slower the change rate of the membrane lipid phase shift angle relative to the change rate of the ice crystal density (the stronger the resistance of the membrane lipid to the growth of the ice crystal), and the higher the cold resistance; the smaller the value, the faster the deterioration of the membrane lipid state with the growth of the ice crystal (the more sensitive the membrane lipid to the stress of the ice crystal), and the lower the cold resistance. represents the time difference decay coefficient, which is used to correct the error caused by time asynchrony in the switching process between the polarization mode and the impedance mode; represents the switching time interval between the polarization mode operation and the impedance mode operation, and needs to satisfy , is the ice crystal nucleation period, and an exemplary value for an apple dormant branch is 50 ms, which is controlled by the FPGA controller.

[0096] is the time correction term, which is close to 1 because is usually very small, and exemplary values are = 0.03, = 0.05, , and its main function is to slightly correct the influence of the time difference on the ratio of the two change rates, ensure the time consistency of the data, eliminate the system error caused by mode switching, and make more accurately quantify the cold resistance.

[0097] S6: determining the cold resistance grade according to the cold resistance synergy index value, so as to intuitively present the difference in cold resistance ability of different samples or varieties.

[0098] When D2 , a high cold resistance identifier is output, wherein D2 represents a high cold resistance threshold value, indicating that the cell membrane lipid of the dormant branch can tolerate a higher density of ice crystal growth under low temperature stress, the change rate of the membrane lipid phase shift angle is much lower than the change rate of the ice crystal density, the risk of freeze damage is extremely low, and the dormant branch is suitable for planting or overwintering in cold regions.

[0099] When D2 , a medium cold resistance identifier is output, and the tolerance of the membrane lipid to the growth of ice crystals is moderate, and serious freeze damage is not easy to occur under moderate low temperature (such as short-term-5℃ to-10℃), but long-term extreme low temperature may cause a certain degree of membrane damage, and appropriate overwintering protection measures need to be taken.

[0100] When D2 , a low cold resistance identifier is output, wherein D2 represents a low cold resistance threshold value, and the membrane lipid is very sensitive to the growth of ice crystals, even a small amount of ice crystal formation can quickly trigger the phase transition of the membrane lipid, and freeze damage is prone to occur, and the dormant branch is only suitable for planting in warm regions or needs to take strict cold protection measures.

[0101] In the embodiments of the present application, and are threshold values of the cold resistance grade, which are determined by sample experiments and have tree species specificity. For example, the typical threshold value of the dormant branch of an apple tree can be set as D2 =5.2, =2.8; and the typical threshold value of the dormant branch of a peach tree can be set as D2 =4.5, =2.2.

[0102] According to the fruit tree dormant branch cold resistance comparison method in the embodiments of the present application, the polarization laser transmission technology (characterizing the ice crystal density of the cell gap) and the impedance spectrum analysis (characterizing the membrane lipid phase shift angle) are combined to quantitatively determine the cold resistance characteristics from the optical and electrical dimensions, avoiding the limitation of a single index, and the detection result is more in line with the actual cold resistance physiological state of the dormant branch. By alternately collecting real-time data in different modes, the change rates of the ice crystal density and the membrane lipid phase shift angle are calculated, the dynamic change of the cold resistance characteristics in the low temperature stress process is tracked, and the cold resistance response of the fruit tree dormant branch in the real low temperature environment is better reflected. At the same time, the present application introduces the “ice crystal-membrane lipid synergy ratio” and the “cold resistance synergy index” to quantitatively determine the synergy mechanism of the ice crystal growth and the membrane lipid damage, and breaks through the surface analysis of the traditional method which only determines the cold resistance through a single physiological index (such as electrical conductivity and survival rate), and reveals the essence of cold resistance from the molecular level.

[0103] In the description of the application, the terms "first", "second", "third", etc. are used only for the purpose of description, and are not to be interpreted as indicating or implying relative importance or a specific number of the technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. The meaning of "a plurality of" is two or more, unless specifically limited otherwise.

[0104] In the present application, unless specifically defined and limited otherwise, the terms "mounting", "connecting", "connecting", "fixing" and the like should be interpreted broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate media, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0105] In the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate media. Moreover, the first feature "above", "over" and "on" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0106] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present application and the features of different embodiments or examples, without contradiction.

[0107] Any processes or methods described in the flowcharts or otherwise described herein can be understood as representing modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions or steps, and alternate implementations are possible that include structure that is not shown or described herein, including implementations that use different terminology, structures, or approaches to achieve the same results. The scope of preferred embodiments of the present application includes any implementation that performs the functions described herein, whether explicitly discussed or not.

[0108] Logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be embodied in computer-readable instructions, such as software and / or firmware, which can be executed by a processing unit, such as a computer or like device. Computer readable instructions can be stored and / or transmitted using a variety of media and / or storage and / or transmission devices, which can include, for example, magnetic storage media (e.g., magnetic disks), optical storage media (e.g., optical disks), electronic storage media (e.g., solid state memory), and / or forms of propagated signals (e.g., carrier waves, acoustical waves, etc.). The computer readable instructions can be executed, for example, by a processing unit, such as a computer or like device, to cause the processing unit to perform the functions described herein.

[0109] It should be understood that aspects of the present application can be implemented in hardware, software, firmware, or combinations thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and in another embodiment, any of the following technologies, or combinations thereof, can be used: a discrete logic circuit having logic gates for implementing logic functions upon data signals, an application specific integrated circuit having appropriate combinational logic gates, a programmable gate array (PGA), a field programmable gate array (FPGA), and / or the like.

[0110] Those skilled in the art can understand that all or part of the steps of the method carried out by the above-mentioned embodiments can be instructed by a program to relevant hardware, and the program can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiments or a combination thereof.

[0111] In addition, each functional unit in each embodiment of the present application can be integrated into one processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The integrated module can be realized in the form of hardware or in the form of a software functional module. When the integrated module is realized in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0112] Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A method for comparing the cold resistance of dormant branches of fruit trees, characterized in that, The method comprises the following steps: Alternately performing polarization mode operation and impedance mode operation on the same detection site of the dormant branch of the fruit tree; wherein, when performing the polarization mode operation, transmitting first waveband laser and second waveband laser to the detection site at a preset incident angle, and collecting a transmission light intensity data set; when performing the impedance mode operation, injecting a sweep frequency current to the detection site, and collecting an impedance component data set of a characteristic frequency point; Calculating cell gap ice crystal density according to the transmission light intensity data set; Calculating membrane lipid phase shift angle according to the impedance component data set; When the cell gap ice crystal density is greater than an activation threshold value, calculating ice crystal-membrane lipid synergy ratio based on the cell gap ice crystal density and the membrane lipid phase shift angle; Calculating cold resistance synergy index according to the change rate of the cell gap ice crystal density and the membrane lipid phase shift angle; Determining cold resistance grade according to the cold resistance synergy index value; The expression of the transmitted light intensity data group is: , wherein, represents the first waveband laser incident light intensity original value; represents the first waveband laser transmitted light intensity real-time value; represents the second waveband laser incident light intensity original value; represents the second waveband laser transmitted light intensity real-time value; The calculation formula of the cell gap ice crystal density is: wherein, represents the intercellular ice crystal density; represents the optical constant of the tree species; represents the temperature compensation coefficient; represents the real-time temperature of the branch surface; represents the freezing point temperature of the tissue; represents the moisture correction factor; The expression of the impedance component data set is: ; The calculation formula of the membrane lipid phase shift angle is: wherein denotes the membrane lipid phase shift angle; denotes the impedance real part; denotes the impedance imaginary part; The calculation formula of the ice crystal-membrane lipid synergy ratio is: wherein, represents the ice crystal-membrane lipid synergy ratio; represents the ice crystal growth rate coefficient; represents the membrane lipid critical phase shift angle; represents the synergy shape factor; represents the maximum tolerated intercellular ice crystal density for the tree species; characterizes the relative degree of ice crystal accumulation; Among them, when At that time, forced =1; The calculation formula of the change rate of the cell gap ice crystal density and the membrane lipid phase shift angle is: wherein and are two adjacent data collection time points; represents the rate of change of intercellular ice crystal density; and are the intercellular ice crystal densities at time points and respectively. representing the rate of change of membrane lipid phase angle; with respectively the time point and membrane lipid phase angle, with and synchronous acquisition; The calculation formula of the cold resistance synergy index is: wherein represents the cold resistance synergy index; represents the time difference attenuation coefficient; represents the switching time interval between polarization mode operation and impedance mode operation, wherein , is the ice crystal nucleation period.

2. The method for comparing cold hardiness of dormant branches of fruit trees according to claim 1, characterized in that, In the impedance mode operation, the selection method of the characteristic frequency point is: Performing 10 kHz-10 MHz full frequency band sweep on the target fruit tree variety; The frequency point with the maximum change rate of the phase angle of the complex impedance is selected as the characteristic frequency point The expression of the characteristic frequency point is wherein , denotes the complex impedance phase angle; denotes the rate of change of the complex impedance phase angle with the frequency of the sweep current.

3. The method for comparing cold resistance of dormant branches of fruit trees according to claim 1, characterized in that, When a high cold resistance flag is output, where represents a high cold resistance threshold; when D2 a medium cold resistance flag is output; when a low cold resistance flag is output, where represents a low cold resistance threshold.

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