Method and device for measuring hydraulic conductivity and biomechanical parameters of fruits

Abstract

The application discloses a kind of fruit hydraulic conductivity and biomechanical parameter measurement method and device;The measurement method includes the following steps: step 1: sampling;Step 2: measure initial fruit water potential Ψ f0 With pressure chamber;Step 3: do fruit water absorption experiment;Step 4: measure fruit pressure-volume curve (P-V curve);Step 5: measure fruit stalk + calyx hydraulic resistance and fruit stalk hydraulic resistance, respectively Rc And Rs;Step 6: data processing.The fruit hydraulic conductivity and biomechanical parameter measurement method and device, the hydraulic conductivity affecting fruit water transport and the biomechanical parameters such as volume elastic modulus, cell wall coefficient of extension, critical point swelling pressure and other influencing factors affecting cell elastoplastic deformation are conveniently obtained, which is convenient for studying fruit swelling growth, and helps to deeply understand the physiological mechanism of fruit cell swelling and its response law to changes in different habitat elements.

Description

Technical Field

[0001] This invention relates to the field of plant analysis technology, specifically to a method and apparatus for measuring the hydraulic conductivity and biomechanical parameters of fruits. Background Technology

[0002] Fruit growth and development involves cell division and cell expansion. Rapid fruit volume growth primarily stems from cell expansion, which determines the final fruit volume and is a crucial factor limiting yield. Cell expansion is driven by turgor pressure generated by water input. This turgor pressure is partly due to elastic deformation caused by changes in turgor pressure and partly due to plastic deformation that occurs when the turgor pressure exceeds a critical point. Therefore, fruit expansion is influenced by the hydraulic conductivity of water transport and biomechanical parameters affecting cell elastic-plastic deformation, such as bulk modulus, cell wall elongation coefficient, and critical point turgor pressure. To gain a deeper understanding of the physiological mechanisms of fruit cell expansion and its response to changes in different habitat factors, it is necessary to develop a method for measuring fruit hydraulic conductivity and biomechanical parameters.

[0003] Currently, there is no method to quantify the hydraulic resistance and biomechanical parameters of fruits. Therefore, it is necessary to develop a method and device for measuring the hydraulic resistance and biomechanical parameters of fruits, which can quickly and accurately measure these parameters. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for measuring the hydraulic conductivity and biomechanical parameters of fruits, so as to solve the problem mentioned in the background art that it is not convenient to quickly and accurately measure the hydraulic resistance and biomechanical parameters of fruits.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method and apparatus for measuring the hydraulic conductivity and biomechanical parameters of a fruit;

[0006] The measurement method includes the following steps:

[0007] Step 1: Sampling;

[0008] Sampling was conducted between 7:00 and 8:00 in the morning. The fruit was cut off from the plant with scissors, with the stem attached. The stem length was selected to be 3-5 cm. After the fruit was removed from the plant, it was immediately placed into a self-sealing bag with a damp cloth and sealed. Then it was immediately placed into an insulated box with ice packs to prevent the fruit from evaporating.

[0009] Step 2: Measure the initial fruit water potential Ψ using a pressure chamber. f0 ;

[0010] Immediately after sampling, the sample was brought back to the laboratory and the initial fruit water potential Ψ was measured using a pressure chamber. f0The measurement is completed within 3 minutes;

[0011] Step 3: Conduct a fruit water absorption test;

[0012] After measuring the water potential of the fruit, the transverse and longitudinal diameters of the fruit were measured with vernier calipers, and the fresh weight of the fruit with stem was weighed with an analytical balance and recorded as FW. Then, the fruit water absorption test was carried out using the fruit water absorption test apparatus.

[0013] Step 4: Measure the pressure-volume curve (PV curve) of the fruit;

[0014] Step 5: Measure the hydraulic resistance of the fruit stalk + calyx and the hydraulic resistance of the fruit stalk, and record them as Rc and Rs respectively;

[0015] After the PV curve test was completed, the fruit part was cut off with a blade in deaerated ionized water, and the hydraulic resistance of the fruit stalk + calyx was measured using the 2m gravity water head method.

[0016] Step 6: Data Processing;

[0017] Data processing includes the following:

[0018] Calculation of hydraulic conductivity Lp for fruit, pedicel, and calyx;

[0019] Calculation of the hydraulic conductivity of the fruit stalk, calyx, and fruit stalk;

[0020] Calculation of hydraulic conductances Lr and Lf of calyx and fruit;

[0021] Calculation of fruit turgor pressure and elastic modulus ε;

[0022] Fruit cell wall stretching coefficient Φ and critical point pressure potential Ψ Y calculate.

[0023] A fruit water absorption experimental device, the fruit water absorption experimental device comprising a component to ensure 100% humidity and a component for fruit to absorb water;

[0024] The 100% humidity component includes a humidifier, a temperature and humidity sensor, a covered plastic box, a storage rack, a towel, and wet wipes. The storage rack is placed at the bottom of the plastic box, the humidifier and temperature and humidity sensor are placed on the storage rack, the wet wipes are attached to the inside of the plastic box, and the wet towel completely covers the top of the plastic box.

[0025] The component for supplying water to the fruit includes centrifuge tubes and deionized water that has undergone negative pressure degassing treatment. The centrifuge tubes are placed on a rack, and the deionized water is contained in the centrifuge tubes.

[0026] Preferably, the specific operating steps of the fruit water absorption experiment are as follows:

[0027] A1. Prepare a water absorption device in advance to ensure that the humidity of the water absorption environment reaches 100%;

[0028] A2. Wrap water-stop tape around the fruit stalk to ensure that the fruit absorbs water only from the cut surface of the stalk. Quickly trim the fruit stalk of the fruit to be tested with a blade in deionized water that has been degassed under negative pressure. After trimming, quickly wipe off the water with absorbent paper and weigh it with an analytical balance. Then quickly connect it to the component that supplies water to the fruit.

[0029] A3. Every so often, take out the water-absorbing fruit, weigh it and measure the fruit water potential. Before each weighing, wipe the fruit dry with absorbent paper. After weighing, put the fruit into the holding rack of the water-absorbing device and balance for 5 minutes. After balancing, use the pressure chamber to measure the fruit water potential within 3 minutes.

[0030] The water absorption test was conducted entirely in a laboratory environment with a constant temperature of 25°C.

[0031] Preferably, the specific operation steps for measuring the PV curve are as follows:

[0032] B1. Prepare 16 12mL glass sample bottles and fill them with cotton to absorb water. Weigh the bottles with the cotton using an analytical balance.

[0033] B2. Place a damp paper towel (6) inside the pressure chamber to maintain high humidity and prevent the fruit from evaporating and losing water;

[0034] B3. Connect the fruit that has undergone the water absorption test to the pressure chamber and pressurize it according to the pressure gradient. During the pressurization process, stabilize at a certain pressure, invert the bottle onto the fruit stem to absorb the water squeezed out, until no water is squeezed out from the fruit stem under this pressure. Immediately remove the bottle, close the cap, weigh it with an analytical balance, and then pressurize to another pressure and repeat the above operation.

[0035] The entire operation was carried out under constant temperature laboratory conditions at 25℃.

[0036] Preferably, the specific procedure for the 2m gravity head method measurement is as follows:

[0037] C1. The fruit stalk and calyx are connected to the gravity head assembly, and the automatic counting assembly automatically records the flushing flow rate F1 through the fruit stalk and calyx within 30 minutes;

[0038] C2. The calyx is then removed in deaerated and deionized water, while the fruit stalk is connected to the gravity head assembly. The automatic counting assembly automatically records the rinsing flow rate F2 through the fruit stalk within 30 minutes.

[0039] C3. After completing the hydraulic conductivity experiment of the fruit stalk, dry the fruit, fruit stalk and calyx to obtain the dry weight, denoted as DW.

[0040] Preferably, the hydraulic conductivity Lp of the fruit + pedicel + calyx is calculated as follows:

[0041] During the water absorption process, the increase in volume of the fruit is equal to the amount of water absorbed, that is:

[0042] dV / dt=Lp*A*(0-Ψ f )

[0043] Then Lp=-dV / dt / (A*Ψ) f )

[0044] in:

[0045] Ψ f —Fruit water potential, bar;

[0046] A – Surface area of ​​the fruit, cm² 2 ;

[0047] Lp – Hydraulic conductivity of pedicel + calyx + fruit, in cm 3 / (cm 2 .min.bar);

[0048] dV / dt — Rate of change of fruit volume, cm 3 / min, since the density of water is 1g / cm³ 3 Therefore, dV / dt is numerically equal to the rate of change of fruit weight, dW / dt, g / min.

[0049] Preferably, the hydraulic conductivity of the fruit stalk + calyx and the fruit stalk is calculated as follows:

[0050] Assume the hydraulic conductivities of the fruit stalk + calyx and the fruit stalk are Lc and Ls, respectively;

[0051] Calculate Lc and Ls using the following formula:

[0052] Lc=F1 / ΔP / A

[0053] Ls=F2 / ΔP / A

[0054] in:

[0055] Lc – Hydraulic conductivity of fruit pedicel + calyx, cm 3 / (cm 2 .min.bar);

[0056] Ls – Hydraulic conductivity of the fruit stalk, cm 3 / (cm 2 .min.bar);

[0057] ΔP — the water potential difference corresponding to a 2-meter water head, i.e., 0.2 bar.

[0058] Preferably, the hydraulic conductances Lr and Lf of the calyx and fruit portions are calculated as follows:

[0059] Lr = 1 / (1 / Lc - 1 / Ls)

[0060] Lf = 1 / (1 / Lp - 1 / Lc)

[0061] Preferably, the fruit turgor pressure and elastic modulus ε are calculated as follows:

[0062] Fully saturated fruit is placed in a pressure chamber, and the equilibrium pressure is gradually increased. Water is gradually forced out of the fruit tissue. The extracted water is collected and weighed. A graph is plotted between the reciprocal of the equilibrium pressure and the cumulative amount of water extracted, called a PV curve. The PV curve consists of a curved segment and a straight segment. The intersection point B of the curved and straight segments is called the turgor pressure loss point, where the turgor pressure is zero and the water potential equals the osmotic potential. On the AB curve segment, the fruit's water potential consists of both osmotic and pressure potentials, and the turgor pressure is greater than zero, representing the difference between the osmotic and equilibrium pressures. On the BC straight segment, the fruit's water potential consists only of osmotic potential, and the turgor pressure is zero. Extending the BC straight line to intersect the vertical axis, the vertical coordinate of the intersection point H is the reciprocal of the negative osmotic potential when the fruit is fully saturated.

[0063] The reciprocal of the negative value of the fruit's water potential at the time t=0 is P0 = -1 / Ψ. f0 Substituting the equation of segment AB in the PV curve above, we obtain the corresponding volume of extruded juice, ΔV0. Substituting ΔV0 into the equation of line BC, we obtain the reciprocal of the equilibrium pressure, P0', and thus calculate the initial osmotic potential Ψ of the fruit. π0 = -1 / P0', thus obtaining the initial fruit pressure potential Ψ. p0 =Ψ f0 -Ψ π0 The negative reciprocal of the total water potential at the time t = 0.5 of fruit water absorption is P1 = -1 / Ψ. f1 Substituting the equation of segment AB of the PV curve into the equation above, we obtain the corresponding volume of extruded juice, ΔV1. Substituting ΔV1 into the equation of line BC, we obtain the reciprocal of the equilibrium pressure, P1'. From this, we can calculate the osmotic potential Ψ of the fruit corresponding to the water absorption time t = 0.5. π1 =-1 / P1', corresponding to the fruit pressure potential Ψ p1 =Ψ π1 -Ψ f1 By analogy, the pressure potential of the fruit at other time points during the water absorption process can be obtained.

[0064] The bulk modulus (ε) of the fruit before turgor pressure dissipation can be calculated using the following formula:

[0065] ε=dΨ p / (dV / V)

[0066] in:

[0067] ε — bulk modulus of elasticity of fruit, (bar.cm) 3 ) / cm 3 ;

[0068] dΨp — Change in fruit pressure potential, in bar;

[0069] dV / V — Relative change in fruit water content, in cm 3 / cm 3 .

[0070] Preferably, the fruit cell wall stretching coefficient Φ and the critical point pressure potential Ψ Y The calculation is as follows:

[0071] The volume expansion of a fruit during water absorption originates from two parts: one part is elastic deformation caused by changes in turgor pressure, and the other part is plastic deformation that occurs when the turgor pressure exceeds the critical point.

[0072] dV / dt=V / ε*dΨ p / dt+Φ.V(Ψ p -Ψ Y )

[0073] In the formula, V / ε*dΨ p / dt is the elastic deformation caused by the change in pressure, Φ.V(Ψ) p -Ψ Y Turbination pressure (V / ε) is the plastic deformation that occurs when the turgor pressure exceeds the critical point pressure. By estimating the turgor pressure and bulk modulus during the fruit's water absorption process using the PV curve, the elastic deformation V / ε*dΨ caused by the change in turgor pressure can be calculated. p / dt, thus obtaining the plastic deformation of the fruit during water absorption (dV / dt-V / ε*dΨp / dt). Rearranging the formula, we get:

[0074] (dV / dt-V / ε*dΨp / dt) / V=Φ(Ψ p -Ψ Y )

[0075] That is, the relative plastic deformation of the fruit during water absorption is linearly related to the fruit turgor pressure. The slope of the line is the fruit cell wall extension coefficient Φ, and the intercept is the product of the fruit cell wall extension coefficient and the critical point pressure potential ΦΨY. Therefore, by performing linear regression on the relative plastic deformation of the fruit and the fruit turgor pressure during water absorption obtained above, the fruit cell wall extension coefficient and the critical point pressure potential can be obtained.

[0076] Compared with the prior art, the beneficial effects of the present invention are: by using a fruit water absorption experimental device to conduct fruit water absorption tests, and combining the fruit water potential measured in a pressure chamber, the PV curve of the fruit can be further plotted, which makes it convenient to obtain the hydraulic conductivity that affects the water transport of the fruit and the biomechanical parameters that affect the elastic-plastic deformation of cells, such as bulk elastic modulus, cell wall elongation coefficient, critical point turgor pressure, etc., which facilitates the study of fruit enlargement and growth, and helps to deeply understand the physiological mechanism of fruit cell enlargement and its response to changes in different habitat elements. Attached Figure Description

[0077] Figure 1 This is a PV curve of the fruit of the present invention;

[0078] Figure 2 This is a graph showing the change in the weight of the fruit after absorbing water over time.

[0079] Figure 3 This is a schematic diagram of the fruit water absorption experimental device of the present invention.

[0080] In the picture: 1. Humidifier; 2. Temperature and humidity sensor; 3. Plastic box with lid; 4. Container rack; 5. Wet towel; 6. Wet paper towel; 7. Centrifuge tube. Detailed Implementation

[0081] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] Please see Figure 1-3 The present invention provides a technical solution: a method for measuring the hydraulic conductivity and biomechanical parameters of fruit;

[0083] The measurement method includes the following steps:

[0084] Step 1: Sampling;

[0085] Sampling was conducted between 7:00 and 8:00 in the morning. The fruit was cut off from the plant with scissors, with the stem attached. The stem length was selected to be 3-5 cm. After the fruit was removed from the plant, it was immediately placed into a self-sealing bag with a damp cloth and sealed. Then it was immediately placed into an insulated box with ice packs to prevent the fruit from evaporating.

[0086] Step 2: Measure the initial fruit water potential Ψ using a pressure chamber. f0 ;

[0087] Immediately after sampling, the sample was brought back to the laboratory and the initial fruit water potential Ψ was measured using a pressure chamber. f0 The measurement is completed within 3 minutes;

[0088] Step 3: Conduct a fruit water absorption test;

[0089] After measuring the water potential of the fruit, the transverse and longitudinal diameters of the fruit were measured with vernier calipers, and the fresh weight of the fruit with stem was weighed with an analytical balance and recorded as FW. Then, the fruit water absorption test was carried out using the fruit water absorption test apparatus.

[0090] Step 4: Measure the pressure-volume curve (PV curve) of the fruit;

[0091] Step 5: Measure the hydraulic resistance of the fruit stalk + calyx and the hydraulic resistance of the fruit stalk, and record them as Rc and Rs respectively;

[0092] After the PV curve test was completed, the fruit part was cut off with a blade in deaerated ionized water, and the hydraulic resistance of the fruit stalk + calyx was measured using the 2m gravity water head method.

[0093] Step 6: Data Processing;

[0094] Data processing includes the following:

[0095] Calculation of hydraulic conductivity Lp for fruit, pedicel, and calyx;

[0096] Calculation of the hydraulic conductivity of the fruit stalk, calyx, and fruit stalk;

[0097] Calculation of hydraulic conductances Lr and Lf of calyx and fruit;

[0098] Calculation of fruit turgor pressure and elastic modulus ε;

[0099] Fruit cell wall stretching coefficient Φ and critical point pressure potential Ψ Y calculate.

[0100] A fruit water absorption experimental device, comprising a component to maintain 100% humidity and a component for the fruit to absorb water.

[0101] The 100% humidity component includes a humidifier 1, a temperature and humidity sensor 2, a covered plastic box 3, a rack 4, a towel 5, and wet wipes 6. The rack 4 is placed at the bottom of the plastic box, the humidifier 1 and the temperature and humidity sensor 2 are placed on the rack 4, the wet wipes 6 are attached to the inside of the plastic box, and the wet towel 5 completely covers the top of the plastic box.

[0102] The components for the fruit to absorb water include centrifuge tubes 7 and deionized water that has been degassed under negative pressure. Centrifuge tubes 7 are placed on a rack 4, and deionized water is contained in centrifuge tubes 7.

[0103] The specific steps for the fruit water absorption experiment are as follows:

[0104] A1. Prepare a water absorption device in advance to ensure that the humidity of the water absorption environment reaches 100%;

[0105] A2. Wrap water-stop tape around the fruit stalk to ensure that the fruit absorbs water only from the cut surface of the stalk. Quickly trim the fruit stalk of the fruit to be tested with a blade in deionized water that has been degassed under negative pressure. After trimming, quickly wipe off the water with absorbent paper and weigh it with an analytical balance. Then quickly connect it to the component that supplies water to the fruit.

[0106] A3. Every so often, remove the water-absorbing fruit, weigh it, and measure its water potential. The measurement time points are shown in Table 1. Before each weighing, wipe the fruit dry with absorbent paper. After weighing, place the fruit on the holding rack of the water-absorbing device to balance for 5 minutes. After balancing, measure the fruit water potential using the pressure chamber within 3 minutes.

[0107] Table 1 Time Nodes

[0108]

[0109]

[0110] The water absorption test was conducted entirely in a laboratory environment with a constant temperature of 25°C.

[0111] The specific steps for measuring the PV curve are as follows:

[0112] B1. Prepare 16 12mL glass sample bottles and fill them with cotton to absorb water. Weigh the bottles with the cotton using an analytical balance.

[0113] B2. Place a damp paper towel (6) inside the pressure chamber to maintain high humidity and prevent the fruit from evaporating and losing water;

[0114] B3. Connect the fruit that has undergone the water absorption test to the pressure chamber and pressurize it according to the pressure gradient in Table 2. During the pressurization process, stabilize at a certain pressure, invert the bottle onto the fruit stem to absorb the water squeezed out, until no water is squeezed out from the fruit stem under this pressure. Immediately remove the bottle, close the cap, weigh it with an analytical balance, and then pressurize to another pressure and repeat the above operation.

[0115] Table 2 Pressure Gradient Table

[0116]

[0117] The entire operation was carried out under constant temperature laboratory conditions at 25℃.

[0118] The specific procedure for measuring using the 2m gravity head method is as follows:

[0119] C1. The fruit stalk and calyx are connected to the gravity head assembly, and the automatic counting assembly automatically records the flushing flow rate F1 through the fruit stalk and calyx within 30 minutes;

[0120] C2. The calyx is then removed in deaerated and deionized water, while the fruit stalk is connected to the gravity head assembly. The automatic counting assembly automatically records the rinsing flow rate F2 through the fruit stalk within 30 minutes.

[0121] C3. After completing the hydraulic conductivity experiment of the fruit stalk, dry the fruit, fruit stalk and calyx to obtain the dry weight, denoted as DW.

[0122] The hydraulic conductance Lp of fruit + pedicel + calyx is calculated as follows:

[0123] During the water absorption process, the increase in volume of the fruit is equal to the amount of water absorbed, that is:

[0124] dV / dt=Lp*A*(0-Ψ f )

[0125] Then Lp=-dV / dt / (A*Ψ) f )

[0126] in:

[0127] Ψ f —Fruit water potential, bar;

[0128] A – Surface area of ​​the fruit, cm² 2 ;

[0129] Lp – Hydraulic conductivity of pedicel + calyx + fruit, in cm 3 / (cm 2 .min.bar);

[0130] dV / dt — Rate of change of fruit volume, cm 3 / min, since the density of water is 1g / cm³ 3 Therefore, dV / dt is numerically equal to the rate of change of fruit weight, dW / dt, g / min.

[0131] The hydraulic conductivity of the fruit stalk, calyx, and fruit stalk is calculated as follows:

[0132] Assume the hydraulic conductivities of the fruit stalk + calyx and the fruit stalk are Lc and Ls, respectively;

[0133] Calculate Lc and Ls using the following formula:

[0134] Lc=F1 / ΔP / A

[0135] Ls=F2 / ΔP / A

[0136] in:

[0137] Lc – Hydraulic conductivity of fruit pedicel + calyx, cm 3 / (cm 2 .min.bar);

[0138] Ls – Hydraulic conductivity of the fruit stalk, cm 3 / (cm 2 .min.bar);

[0139] ΔP — the water potential difference corresponding to a 2-meter water head, i.e., 0.2 bar.

[0140] The hydraulic conductances Lr and Lf of the calyx and fruit are calculated as follows:

[0141] Lr = 1 / (1 / Lc - 1 / Ls)

[0142] Lf = 1 / (1 / Lp - 1 / Lc)

[0143] The fruit turgor pressure and elastic modulus ε are calculated as follows:

[0144] Fully saturated fruit is placed in a pressure chamber, and the equilibrium pressure is gradually increased. Water is gradually forced out of the fruit tissue. The extracted water is collected and weighed. A graph is plotted between the reciprocal of the equilibrium pressure and the cumulative amount of water extracted. Figure 1 The diagram shown is called the PV curve. The PV curve consists of two parts: a curved segment and a straight segment. The intersection point B of the curved and straight segments is called the turgor pressure loss point, where the turgor pressure is zero and the water potential equals the osmotic potential. On the AB curve segment, the fruit's water potential is composed of osmotic potential and pressure potential; the turgor pressure is greater than zero, representing the difference between osmotic pressure and equilibrium pressure. On the BC straight segment, the fruit's water potential consists only of osmotic potential; the fruit's turgor pressure is zero. Extending the BC straight line to intersect the vertical axis, the vertical coordinate of the intersection point H is the reciprocal of the negative osmotic potential when the fruit is fully saturated.

[0145] The reciprocal of the negative value of the fruit's water potential at the time t=0 is P0 = -1 / Ψ. f0 Substituting the equation of segment AB in the PV curve above, we obtain the corresponding volume of extruded juice, ΔV0. Substituting ΔV0 into the equation of line BC, we obtain the reciprocal of the equilibrium pressure, P0', and thus calculate the initial osmotic potential Ψ of the fruit. π0 = -1 / P0', thus obtaining the initial fruit pressure potential Ψ. p0 =Ψ f0 -Ψ π0 The negative reciprocal of the total water potential at the time t = 0.5 of fruit water absorption is P1 = -1 / Ψ. f1 Substituting the equation of segment AB of the PV curve into the equation above, we obtain the corresponding volume of extruded juice, ΔV1. Substituting ΔV1 into the equation of line BC, we obtain the reciprocal of the equilibrium pressure, P1'. From this, we can calculate the osmotic potential Ψ of the fruit corresponding to the water absorption time t = 0.5. π1 =-1 / P1', corresponding to the fruit pressure potential Ψ p1 =Ψ π1 -Ψ f1Similarly, the pressure potential of the fruit at other time points during the water absorption process can be obtained.

[0146] The bulk modulus (ε) of the fruit before turgor pressure dissipation can be calculated using the following formula:

[0147] ε=dΨ p / (dV / V)

[0148] in:

[0149] ε — bulk modulus of elasticity of fruit, (bar.cm) 3 ) / cm 3 ;

[0150] dΨp — Change in fruit pressure potential, in bar;

[0151] dV / V — Relative change in fruit water content, in cm 3 / cm 3 .

[0152] Fruit cell wall stretching coefficient Φ and critical point pressure potential Ψ Y The calculation is as follows:

[0153] The volume expansion of a fruit during water absorption originates from two parts: one part is elastic deformation caused by changes in turgor pressure, and the other part is plastic deformation that occurs when the turgor pressure exceeds the critical point.

[0154] dV / dt=V / ε*dΨ p / dt+Φ.V(Ψ p -Ψ Y )

[0155] In the formula, V / ε*dΨ p / dt is the elastic deformation caused by the change in pressure, Φ.V(Ψ) p -Ψ Y Turbination pressure (V / ε) is the plastic deformation that occurs when the turgor pressure exceeds the critical point pressure. By estimating the turgor pressure and bulk modulus during the fruit's water absorption process using the PV curve, the elastic deformation V / ε*dΨ caused by the change in turgor pressure can be calculated. p / dt, thus obtaining the plastic deformation of the fruit during water absorption (dV / dt-V / ε*dΨp / dt). Rearranging the formula, we get:

[0156] (dV / dt-V / ε*dΨp / dt) / V=Φ(Ψ p -Ψ Y )

[0157] That is, the relative plastic deformation of the fruit during water absorption is linearly related to the fruit turgor pressure. The slope of the line is the fruit cell wall extension coefficient Φ, and the intercept is the product of the fruit cell wall extension coefficient and the critical point pressure potential ΦΨY. Therefore, by performing linear regression on the relative plastic deformation of the fruit and the fruit turgor pressure during water absorption obtained above, the fruit cell wall extension coefficient and the critical point pressure potential can be obtained.

[0158] The contents not described in detail in this specification are prior art known to those skilled in the art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring fruit hydraulic conductivity and biomechanical parameters, characterized in that: the method comprises the following steps: Step 1: sampling; the sampling time is between 7:00 and 8:00 in the morning, the fruit is cut from the plant with a fruit stalk using scissors, fruit stalks with a length of 3-5 cm are selected, the fruit is immediately placed in a self-sealing bag with a wet towel after being separated from the plant, and then immediately placed in an insulation box with an ice bag to prevent fruit transpiration; Step 3: fruit water absorption experiment; after measuring the fruit water potential, the fruit transverse and longitudinal diameters are measured using a vernier caliper, and the fresh weight of the fruit with the stalk is weighed using an analytical balance, which is recorded as FW, and then the fruit water absorption experiment is started through the fruit water absorption experiment device; Step 4: measuring the pressure-volume curve (P-V curve) of the fruit; Step 5: measuring the hydraulic resistance of the fruit stalk + calyx and the fruit stalk, which are recorded as Rc and Rs, respectively; the fruit after the P-V curve experiment is cut in deionized water using a blade, the hydraulic resistance of the fruit stalk + calyx is measured using a 2m gravity water head method, and the 2m gravity water head method measurement process is as follows: C1. The fruit stalk and calyx are connected to the gravity water head assembly, and the automatic recording assembly automatically records the flushing flow rate F1 through the fruit stalk and calyx within 30 minutes; C2. Then, the calyx part is cut in deionized water, the fruit stalk is connected to the gravity water head assembly, and the automatic recording assembly automatically records the flushing flow rate F2 through the fruit stalk within 30 minutes; C3. After the fruit stalk hydraulic conductivity experiment is completed, the fruit, fruit stalk and calyx are dried to obtain the dry weight, which is recorded as DW; Step 6: data processing; the data processing includes the following contents: the fruit + fruit stalk + calyx hydraulic conductivity Lp is calculated as follows: in the fruit water absorption process, the volume of the fruit increases, which is equal to the amount of water absorbed, that is: ΔV = Lp * ΔP * A wherein: ΔV is the volume of the fruit; Lp is the fruit + fruit stalk + calyx hydraulic conductivity; ΔP is the water potential difference corresponding to 2m water head, that is, 0.2bar; A is the cross-sectional area of the fruit; the fruit stalk + calyx and fruit stalk hydraulic conductivities are calculated as follows: assuming that the fruit stalk + calyx and fruit stalk hydraulic conductivities are Lc and Ls, respectively; Lc and Ls are calculated by the following formula: Lc = F1 / ΔP / A Ls = F2 / ΔP / A wherein: ΔP is the water potential difference corresponding to 2m water head, that is, 0.2bar; the fruit + calyx and fruit hydraulic conductivities Lr and Lf are calculated as follows: Lr = 1 / (1 / Lc - 1 / Ls) Lf = 1 / (1 / Lp - 1 / Lc); the fruit turgor pressure and elastic modulus ε are calculated as follows: the fully saturated fruit is placed in a pressure chamber, the equilibrium pressure is gradually increased, the water in the fruit tissue is gradually pressed out, the pressed water is collected and weighed, and the reciprocal of the equilibrium pressure is plotted with the cumulative amount of water pressed out, which is called a P-V curve graph, the P-V curve is divided into two parts, a curve segment and a straight line segment, the intersection point B of the curve segment and the straight line segment is called the turgor pressure loss point, at this time the turgor pressure is zero, the water potential is equal to the osmotic potential, the fruit water potential on the AB curve segment is composed of the osmotic potential and the pressure potential, the turgor pressure is greater than zero, which is the difference between the osmotic pressure and the equilibrium pressure, the fruit water potential on the BC straight line segment is only composed of the osmotic potential, the turgor pressure of the fruit is zero, the BC straight line is extended to intersect with the vertical coordinate axis, and the vertical coordinate value of the intersection point H is the reciprocal of the negative value of the fruit osmotic potential when it is fully saturated. ​ ​ ​ Step 2: Measure initial fruit water potential, Ψ, with pressure chamber f0 ; Immediately after sampling, the fruit was brought to the laboratory and the initial fruit water potential was measured in a pressure chamber f0 Measurements were completed within 3 minutes. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ dV / dt = Lp * A * (0 - Ψ f ) Lp = -dV / dt / (A*Ψ f ) ​ Ψ f - fruit water potential, bar; A - surface area of the fruit, cm 2 ; Lp - hydraulic conductance of the fruit stalk + calyx + fruit, cm 3 (cm 2 .min.bar) dV / dt - rate of change of fruit volume, cm 3 / min, since the density of water is 1 g / cm 3 , dV / dt is numerically equal to the rate of change of fruit weight, dW / dt, g / min; ​ ​ ​ ​ ​ ​ Lc - hydraulic conductance of fruit stalk + calyx, cm 3 (cm 2 .min.bar) Ls - hydraulic conductance of the fruit stalk, cm 3 (cm 2 .min.bar) ​ ​ ​ ​ ​ ​ The reciprocal of the negative value of fruit water potential at the fruit water absorption time t=0 is P0=-1 / Ψ f0 The AB segment curve equation in the above P-V curve is brought in to obtain the volume of pressed juice ΔV0 corresponding to it, ΔV0 is substituted into the linear equation BC to obtain the reciprocal P0' of the corresponding equilibrium pressure, and the initial fruit osmotic potential Ψ is obtained π0 = -1 / P0', so the initial fruit pressure potential Ψ is obtained p0 = Ψ f0 - Ψ π0 The reciprocal of the negative value of total water potential at the fruit water absorption time t=0.5 is P1=-1 / Ψ f1 The AB segment curve equation in the above P-V curve equation is brought in to obtain the volume of pressed juice ΔV1 corresponding to it, ΔV1 is substituted into the linear equation BC to obtain the reciprocal P1' of the corresponding equilibrium pressure, and the fruit osmotic potential Ψ corresponding to the water absorption time t=0.5 is obtained π1 = -1 / P1', the corresponding fruit pressure potential Ψ p1 = Ψ π1 - Ψ f1 , and the pressure potential of the fruit at other time points in the water absorption process is obtained in turn. The volume elastic modulus (ε) of the whole fruit before the turgor pressure dissipates can be calculated by the following formula: ε = dψ p (dV / V) Wherein: ε - fruit volume modulus of elasticity, (bar.cm 3 / cm 3 ; dΨp - the change of fruit pressure potential, bar; dV / V - relative change in fruit water content, cm 3 / cm 3 ; Fruit cell wall extensibility coefficient Φ and critical point pressure potential Ψ Y This is calculated as follows: The volume expansion during the fruit water absorption process is derived from two parts, one part is the elastic deformation caused by the change of turgor pressure, and the other part is the plastic deformation caused by the turgor pressure exceeding the critical point pressure, that is dV / dt = V / ε * dΨ p / dt + Φ.V(Ψ p -Ψ Y ) where V / ε*dΨp / dt is the elastic deformation due to the change of turgor pressure, Φ.V(Ψp) is the plastic deformation after the turgor pressure exceeds the critical point pressure, and V and ε are the volume and the elastic modulus of the fruit, respectively. p where V / ε*dΨp / dt is the elastic deformation due to the change of turgor pressure, Φ.V(Ψp) is the plastic deformation after the turgor pressure exceeds the critical point pressure, and V and ε are the volume and the elastic modulus of the fruit, respectively. p -Ψ Y ) is the plastic deformation after the turgor pressure exceeds the critical point pressure, and V and ε are the volume and the elastic modulus of the fruit, respectively. p where V / ε*dΨp / dt is the elastic deformation due to the change of turgor pressure, Φ.V(Ψp) is the plastic deformation after the turgor pressure exceeds the critical point pressure, and V and ε are the volume and the elastic modulus of the fruit, respectively. (dV / dt - V / ε * dΨp / dt) / V = Φ(Ψ p -Ψ Y ) That is, the relative plastic deformation of fruit during water absorption is linearly related to the turgor pressure of fruit, the slope of the straight line is the fruit cell wall extension coefficient Φ, and the intercept is the product of the fruit cell wall extension coefficient and the critical point pressure potential ΦΨ Y Therefore, by linearly regressing the relative plastic deformation of fruit during water absorption and the turgor pressure of fruit obtained by the above calculation, the fruit cell wall extension coefficient and the critical point pressure potential are obtained.

2. The method for measuring fruit hydraulic conductance and biomechanical parameters according to claim 1, characterized in that: The fruit water absorption experiment device comprises a 100% humidity component and a fruit water absorption component; The 100% humidity component comprises a humidifier (1), a temperature and humidity sensor (2), a plastic box with a cover (3), a storage rack (4), a wet towel (5) and a wet paper (6), the storage rack (4) is placed at the bottom of the plastic box, the humidifier (1) and the temperature and humidity sensor (2) are placed on the storage rack (4), the wet paper (6) is attached to the inside of the plastic box, and the wet towel (5) covers the top of the plastic box; The fruit water absorption component comprises a centrifugal tube (7) and deionized water treated by negative pressure degassing, the centrifugal tube (7) is placed on the storage rack (4), and the deionized water is placed in the centrifugal tube (7).

3. The method for measuring fruit hydraulic conductance and biomechanical parameters according to claim 1, characterized in that: The specific operation steps of the fruit water absorption experiment are as follows: A1. Prepare the water absorption device in advance, and make the water absorption environment humidity reach 100%; A2. Wrap the water stop tape around the fruit stem to ensure that the fruit only absorbs water from the fruit stem cut surface, quickly trim the fruit stem of the fruit to be tested in the deionized water treated by negative pressure degassing with a blade, and quickly wipe off the water with the water absorption paper after trimming, weigh and count with the analytical balance, and then quickly connect with the fruit water absorption component; A3. Every time interval, take out the water absorption fruit to weigh and measure the fruit water potential, wipe off the water on the fruit with the water absorption paper before weighing each time, place the fruit on the storage rack of the water absorption device after weighing, balance for 5 minutes, and measure the water potential with the pressure chamber within 3 minutes; The whole water absorption test is carried out in a laboratory environment with a constant temperature of 25℃.

4. The method for measuring fruit hydraulic conductance and biomechanical parameters according to claim 1, characterized in that: The specific operation steps of the P-V curve measurement are as follows: B1. Prepare 16 12mL glass sample bottles, and fill them with cotton for water absorption, and weigh the initial weight of the bottle with cotton with the analytical balance; B2. Put wet paper (6) in the inner cavity of the pressure chamber to keep the chamber cavity high humidity and prevent the fruit from losing water by transpiration; B3. Connect the fruit after the water absorption test with the pressure chamber, pressurize according to the pressure gradient, during the pressurizing process, stabilize a certain pressure, and place the bottle upside down on the fruit stem to absorb the water pressed out, until the fruit stem does not discharge water at this pressure, take the bottle immediately, cover it with the bottle cap, weigh it with the analytical balance, and then pressurize to another pressure to repeat the above operation; The whole operation is carried out in a constant temperature laboratory environment with a temperature of 25℃.

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