Method and device for measuring photosynthetic rate of plant leaf based on C13 isotope labeling

Abstract

The invention provides a method and device for measuring the photosynthetic rate of plant leaves based on C13 isotope labeling, and belongs to the technical field of biology. The method comprises the following steps: putting a to-be-detected leaf into an assimilation leaf chamber, marking the to-be-detected leaf with 13CO2, measuring the change of 13C content of a specific leaf part before and after marking through an element analyzer and a stable isotope proportion mass spectrometer, and calculating the assimilation 13C amount of the leaf part in unit area and unit time, namely the photosynthetic rate. According to the method and the device, the photosynthetic rates of a plurality of parts on the blade can be measured at the same time, and the measurement efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and particularly relates to a method and a device for measuring the photosynthetic rate of plant leaves based on carbon 13 isotope labeling. Background Art

[0002] The growth of green plants depends on the photosynthesis of leaves, so the photosynthetic rate is one of the most important traits reflecting the growth status of plants. However, the photosynthetic rate of plants varies greatly in different parts of the same leaf. In practice, researchers usually only measure the photosynthetic rate of a certain part of the leaf to represent the whole, but this single-point measurement will inevitably lead to errors. In-depth research on the spatial heterogeneity of photosynthetic rate within leaves is of great significance for accurately evaluating the photosynthetic capacity of plants and accurate modeling at the plant level.

[0003] At present, several methods have been developed at home and abroad to measure the heterogeneity of photosynthetic rate in different parts of leaves, but they all have their own limitations. The leaf dry weight method and iodine staining method have large errors due to the transport of assimilates; the chlorophyll fluorescence method and carbon 14 isotope (radioactive) labeling method can only perform qualitative characterization but not quantitative measurement; portable photosynthetic meters can only measure the photosynthetic rate of a single point each time, and the stabilization time before measurement is long, which is inefficient. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a 13 The method and device for measuring the photosynthetic rate of plant leaves by using C isotope labeling can accurately and efficiently measure the photosynthetic rate of different parts of the leaves.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a method for determining the photosynthetic rate of plant leaves based on carbon 13 isotope labeling, wherein the plant leaves are photosynthetically induced and the photosynthetic rate is measured by using a carbon 13 isotope-labeled plant leaf. 13 CO 2 The mixed gas is used to assimilate the leaves after photosynthesis induction; the leaf mass per unit area LMA, the carbon content in the dry matter and the carbon content in the dry matter of the leaves after assimilation marking are measured. 13 The ratio of C to total C is used to calculate the local photosynthetic rate of leaves according to the following formula:

[0007]

[0008] Where C% is the carbon content in dry matter, R label Is the labeled sample 13 The ratio of C to total C, R ref In the unlabeled sample 13 The ratio of C to total C, t is the assimilation labeling time, m c yes13 The molecular weight of the C atom.

[0009] As an implementation method, the assimilated leaf is divided into several leaf tissues, and the area a of the leaf tissue is measured. leaf The leaf mass per unit area (LMA) was calculated from the dry weight (DW).

[0010] As an embodiment, the leaf tissue is dried and ground into powder, and the carbon content in the leaf dry matter is measured using an element analyzer, and the carbon content in the leaf dry matter is measured using a stable isotope ratio mass spectrometer. 13 The ratio of C to total C.

[0011] As an embodiment, the mixed gas includes a concentration of 400-410 ppm 13 CO 2 and nitrogen and oxygen, the 13 CO 2 The volume ratio of nitrogen to oxygen is 1:2500, and the volume ratio of nitrogen to oxygen in the nitrogen to oxygen is 4:1. The relative humidity of the mixed gas is 50-70%.

[0012] As an embodiment, the flow rate of the nitrogen and oxygen is adjusted to not less than 40 L·min -1 , 13 CO 2 The flow rate is adjusted according to the nitrogen and oxygen flow rates.

[0013] As an embodiment, the photosynthetic induction time is 20-40 minutes, and the assimilation labeling time is 2-3 minutes.

[0014] The present invention also provides a device for measuring the photosynthetic rate of plant leaves based on the above method, the device comprising an air source, a gas mixing box (3) and an assimilation leaf chamber (4), wherein the air source is 13 CO 2 Device (1) and nitrogen oxygen device (2), the 13 CO 2 The device (1) and the nitrogen and oxygen device (2) are connected to the gas mixing box (3) via a pipeline provided with a flow control meter (8), and the gas mixing box (3) is connected to the assimilation leaf chamber (4) via a pipeline; one end of the assimilation leaf chamber (4) is connected to a tail gas absorption device (5); a light source (6) is provided above the assimilation leaf chamber (4), and a fan (7) is provided inside.

[0015] As an implementation mode, the assimilation leaf chamber (4) is made of a transparent material, a plurality of which are provided and are all connected to the gas mixing box (3) and the tail gas absorption device (5) through pipelines.

[0016] As an implementation mode, the assimilation leaf chamber (4) is divided into an upper cover and a lower box body, and the lower box body is provided with a flange and a gasket to seal with the upper cover; one end of the assimilation leaf chamber is a movable opening for placing the leaf to be tested.

[0017] As an embodiment, the tail gas absorption device (5) is filled with NaOH solution, which can absorb CO in the tail gas. 2 .

[0018] Beneficial effects:

[0019] Based on the principle of isotope labeling, the present invention proposes a new method for measuring the photosynthetic rate of plant leaves. The leaves to be tested are first placed in an assimilation leaf chamber and used 13 CO 2 Mark them and then measure the leaf mass per unit area LMA, carbon content in leaf dry matter, 13 The ratio of C to total C is used to calculate the local photosynthetic rate of the leaf according to the formula. The present invention also provides a device for measuring the photosynthetic rate of plant leaves based on the above method. The method and device of the present invention can simultaneously measure the photosynthetic rate of multiple parts on the same leaf, greatly improving the measurement efficiency and achieving high accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The structure diagram of the device for measuring photosynthetic rate of plant leaves of the present invention; wherein 1 is 13 CO 2 Device, 2 is a nitrogen and oxygen device, 3 is a gas mixing box, 4 is an assimilation leaf chamber, 5 is an exhaust gas absorption device, 6 is a light source, 7 is a fan, 8 is a flow control meter, and 9 is a blade.

[0021] Figure 2 is the photosynthetic rate (A 13C )Distribution pattern results in the same leaf of corn.

[0022] Figure 3 for 13 C marks newly assimilated 2 minutes later 13 The transport situation of C.

[0023] Figure 4 The photosynthetic rate (P n ) and this patent 13 CO 2 The photosynthetic rate (A) measured by the labeling method 13C ). The solid line is the 1:1 line; the dotted line is the regression fitting line. DETAILED DESCRIPTION

[0024] Carbon 13 isotope is an important tool in the field of plant physiology and ecology and is usually used for tracing. The present invention provides a method for measuring the photosynthetic rate of plant leaves based on carbon 13 isotope labeling. 13 CO 2 The leaves were marked and the specific leaf parts were measured before and after marking. 13 The change in the ratio of 100% C to total C can accurately and efficiently measure the photosynthetic rate of different parts of the leaves.

[0025] The method of the present invention comprises: inducing photosynthesis in plant leaves, using 400ppm 13 CO 2 The mixed gas is used to assimilate the leaves after photosynthesis induction; the leaf mass per unit area LMA, the carbon content in the dry matter and the carbon content in the dry matter of the leaves after assimilation marking are measured. 13 The ratio of C to total C is used to calculate the local photosynthetic rate of leaves according to the following formula:

[0026]

[0027] Where C% is the carbon content in dry matter, R label Is the labeled sample 13 The ratio of C to total C, R ref In the unlabeled sample 13 The ratio of C to total C, t is the assimilation labeling time, m c yes 13 The molecular weight of the C atom.

[0028] The present invention performs photosynthetic induction on plant leaves so that the leaves reach a relatively stable photosynthetic state. As an embodiment, the leaves are placed in a photosynthetic induction chamber for photosynthetic induction. Operably, one end of the photosynthetic assimilation chamber is opened, and the leaves to be tested are placed, and the connection between the leaves and the leaf chamber is sealed, such as using a foaming glue for sealing. A light source is placed above the photosynthetic assimilation chamber, and the upper cover of the photosynthetic assimilation chamber is opened to perform photosynthetic induction on the leaves, and the light source provides sufficient light for the photosynthesis of the plant. As an embodiment, the light source is an LED light source. As an embodiment, the photosynthetic induction time of the present invention is 20-40 minutes, and more preferably 25-35 minutes, to ensure that the photosynthetic induction of the leaves is complete.

[0029] The present invention conducts photosynthetic induction on the leaves. 13 CO 2 Assimilation marker. 13 CO 2 The mixed gas of the present invention includes a gas having a concentration of 400-410 ppm. 13 CO 2 In addition, it also includes nitrogen and oxygen. 13 CO2 The volume ratio of nitrogen to oxygen is 1:2500, and the volume ratio of nitrogen to oxygen in the nitrogen oxygen is 4:1. As an embodiment, the nitrogen oxygen is 80% by volume N 2 and 20% O 2 , which is close to the current atmospheric environment. 13 CO 2 The gas is mixed with the nitrogen and oxygen to obtain the above mixed gas. 13 CO 2 The ratio of the flow rate of the nitrogen and oxygen to the flow rate of the nitrogen and oxygen is 1:2500. As an embodiment, the flow rate of the injected nitrogen and oxygen is adjusted to not less than 40L·min -1 When the flow rate of nitrogen and oxygen is adjusted to 40L·min -1 When 13 CO 2 The flow rate was adjusted to 16 mL min -1 . The ratio of the mixed gas injected by the present invention is close to that of the gas in the current environment, and the photosynthesis state of the plant leaves is not changed. The temperature and humidity of the mixed gas injected by the present invention are as close as possible to the current environment, reducing the measurement error during marking caused by drastic fluctuations in temperature and humidity. As an embodiment, the relative humidity of the mixed gas described in the present invention is 50-70%, and further 55-65%; the temperature of the mixed gas is 25-30°C, and further 27-29°C. The assimilation marking time of the present invention is preferably 2-3 minutes, which can ensure sufficient marking on the leaves 13 C isotopes can meet the measurement requirements; it can also prevent the labeling time from being too long, which may lead to the transport of assimilates in different parts of the leaves and cause errors.

[0030] The present invention takes out the assimilation-marked leaves and divides the assimilation-marked leaves into several leaf tissues according to the detection purpose, and the leaf tissues avoid the main veins of the leaves when dividing. As an embodiment, the assimilation-marked leaves are evenly cut into several sections from the top to the bottom. The leaf mass per unit area LMA, the carbon content in the dry matter and the carbon content in the dry matter of each leaf tissue are measured. 13 The ratio of C to total C.

[0031] As an embodiment, the method for measuring the leaf mass per unit area LMA is as follows: measuring the leaf area (a leaf , cm 2 ) and then dried to obtain the dry weight (DW, g) and leaf mass per unit area (LMA, g·cm -2 ) is equal to the leaf tissue dry weight divided by the leaf tissue leaf area.

[0032] As an embodiment, the leaf tissue is dried and ground into powder, and the carbon content in the leaf dry matter is measured using an element analyzer, and the carbon content in the leaf dry matter is measured using a stable isotope ratio mass spectrometer. 13 The ratio of C to total C. The specific determination method is carried out according to the instrument instruction manual and conventional operations in the field.

[0033] The local photosynthetic rate of leaves was calculated according to the following formula:

[0034]

[0035] Where C% is the carbon content in dry matter (dimensionless); R label Is the labeled sample 13 Ratio of C to total C (dimensionless); R ref In the unlabeled sample 13 The ratio of C to total C (dimensionless); t is the assimilation labeling time (s); m c yes 13 The molecular weight of C atoms (13 g·mol -1 ).

[0036] The above method of the present invention can simultaneously measure the photosynthetic rates of multiple parts on the same leaf, greatly improving the measurement efficiency and achieving high accuracy of the measurement results.

[0037] The present invention also provides a device for measuring the photosynthetic rate of plant leaves based on the above method, the device comprising an air source, a gas mixing box 3 and an assimilation leaf chamber 4, the air source is 13 CO 2 Device 1 and nitrogen oxygen device 2, the 13 CO 2 The device 1 and the nitrogen and oxygen device 2 are connected to the gas mixing box 3 through a pipeline provided with a flow control meter 8, and the gas mixing box 3 is connected to the assimilation leaf chamber 4 through a pipeline; one end of the assimilation leaf chamber 4 is connected to a tail gas absorption device 5; a light source 6 is provided above the assimilation leaf chamber 4, and a fan 7 is provided inside.

[0038] The assimilation leaf chamber 4 of the present invention is to carry out 13 CO 2 The main container for marking is preferably made of transparent material, such as acrylic plate. As an embodiment, the assimilation leaf chamber 4 is divided into an upper cover and a lower box body, the lower box body is provided with a flange and a gasket to seal with the upper cover; one end of the assimilation leaf chamber is a movable opening for placing the leaf to be tested.

[0039] As an implementation manner, the light source 6 of the present invention is preferably an LED light source, which is arranged directly above the assimilation leaf chamber 4.

[0040] The assimilation chamber 4 of the present invention is provided with a fan 7 for mixing the indoor gas. As an embodiment, the fan 7 is preferably located near the air inlet of the assimilation chamber 4.

[0041] As an embodiment, one end of the assimilation leaf chamber 4 of the present invention is connected to the gas mixing box 3, and the other end is connected to the tail gas absorption device 5. The mixed gas in the gas mixing box 3 is injected into the assimilation leaf chamber 4 and flows out from the pipeline connected to the tail gas absorption device 5. As an embodiment, the tail gas absorption device 5 is filled with NaOH solution to absorb the remaining 13 CO 2 To prevent pollution. The concentration of the NaOH solution can be selected to be 0.1-0.2 mol·L -1 .

[0042] As an implementation mode, the 13 CO 2 Device 1 and nitrogen and oxygen device 2 are high-pressure gas cylinders, which are pressurized to 13 CO 2 Gas and nitrogen and oxygen are injected into the gas mixing box 3. As an embodiment, in the 13 CO 2 A flow control meter 8 is provided in the gas output pipeline of the device 1 and the nitrogen and oxygen device 2 to control 13 CO 2 The outflow rate of the gas and nitrogen and oxygen is adjusted so that the gas in the gas mixing box 3 meets the gas requirements of the assimilation mark.

[0043] As an embodiment, a plurality of assimilation leaf chambers 4 of the present invention may be provided, all of which are connected to the gas mixing box 3 and the tail gas absorption device 5 through pipelines, so as to allow the photosynthetic rates of different leaves to be measured simultaneously, thereby improving the measurement efficiency.

[0044] As an implementation mode, the pipeline is a PVC transparent hose, which connects various devices to form a gas flow path.

[0045] The technical solutions of the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0046] Example 1

[0047] A device for measuring the photosynthetic rate of plant leaves, the device comprising a PVC transparent hose connected to 13 CO 2Device 1, nitrogen and oxygen device 2, gas mixing box 3 and assimilation leaf chamber 4. The assimilation leaf chamber 4 is made of a highly transparent acrylic plate, each of which has a length of 100 cm, a width of 15 cm, a height of 5 cm, and a wall thickness of 0.5 cm. The assimilation leaf chamber is divided into an upper cover and a lower box body, and the lower box body has a flange and a rubber gasket for sealing with the upper cover. One end of the assimilation leaf chamber is open for placing the leaves to be tested.

[0048] Gas connection sequence is as follows Figure 1 As shown. 13 CO 2 The device 1 and the nitrogen and oxygen device 2 are connected to the gas mixing box 3 through a hose provided with a flow control meter 8, and the gas mixing box 3 is connected to the assimilation leaf chamber 4 through a hose; the other end of the assimilation leaf chamber 4 is connected to the tail gas absorption device 5, and the tail gas absorption device 5 is filled with 0.1 mol·L -1 NaOH solution. An LED light source 6 is arranged directly above the assimilation leaf chamber 4, and a fan 7 is arranged at the internal air inlet.

[0049] Example 2

[0050] This example is to measure the photosynthetic rate of different parts of a leaf at an ear position in potted corn at the R2 stage.

[0051] (1) According to Figure 1 The device for measuring the photosynthetic rate of plant leaves is connected as shown. Prepare 4 assimilation leaf chambers, and connect the mixed gas box and the tail gas absorption device with PVC transparent hoses at both ends. Inject the mixed gas into the assimilation leaf chamber through a high-pressure gas cylinder. The mixed gas contains 400ppm 13 CO 2 and 80%-20% nitrogen and oxygen, 13 CO 2 The volume ratio of nitrogen and oxygen is 1:2500. The relative humidity (RH) of the mixed gas is 60-70%. The nitrogen and oxygen high-pressure gas cylinder (80% N 2 and 20% O 2 ) was adjusted to 40 L min -1 ;pure 13 CO 2 The flow rate of the high-pressure gas cylinder was adjusted to 16 mL min by another flow meter (IKFD0-10 SCCM; Beijing Aino). -1 Place an appropriate amount of wet paper towels in the gas mixing box to increase the humidity. Place a gas mixing box near the air inlet with a wind speed of about 0.5 m·s -1 Mixing fan to ensure uniform gas composition in the leaf chamber. -1 The NaOH solution is filtered out of the airflow of the assimilation chamber to absorb the remaining13 CO 2 Prevent contamination. Use air conditioning to control the room temperature to about 29°C and use a humidifier to keep the relative humidity at about 60%.

[0052] (2) Fully extend a corn ear leaf into the assimilation chamber. Use foam glue (gslime; Deli) to seal the connection between the leaf and the assimilation chamber to prevent air leakage. Place the chamber under light, open the upper lid and conduct photosynthetic induction for 30 minutes. The effective photosynthetic light flux density of the leaf part is about 1300 μmol·m -2 ·s -1 , close to the photosynthetic saturation point of corn leaves. The device has four assimilation leaf chambers, so it can accommodate four plants for photosynthetic induction at the same time.

[0053] (3) Cover the assimilation leaf chamber with the upper cover, seal the leaf chamber, and introduce 400ppm 13 CO 2 、80%N 2 and 20% O 2 , RH is 60-70% of the mixed gas. After ventilation for 2 minutes, stop ventilation.

[0054] (4) Cut the marked leaves evenly into eight sections from top to bottom. Cut about 4 cm from each section. 2 When measuring the leaf tissue area (a leaf , cm 2 ) and then dried to obtain the dry weight (DW, g). Leaf mass per unit area (LMA, g·cm -2 ) is equal to DW divided by a leaf .

[0055] (5) The dried leaf tissue was ground into powder, and the carbon content in the leaf dry matter was measured using an elemental analyzer, and the carbon content in the leaf dry matter was measured using a stable isotope ratio mass spectrometer. 13 The ratio of C to total C.

[0056] (6) Samples were also taken from the leaves of corn ears that were not isotopically labeled to determine the carbon content and 13 The ratio of C to total C was used as a control to calculate the local photosynthetic rate of leaves.

[0057] The local photosynthetic rate of leaves (A 13C , μmol·m -2 ·s -1 ) is calculated by the following formula:

[0058]

[0059] Where C% is the carbon content in dry matter (dimensionless); Rlabel Is the labeled sample 13 Ratio of C to total C (dimensionless); R ref In the unlabeled sample 13 The ratio of C to total C (dimensionless); t is the assimilation labeling time (s); m c yes 13 The molecular weight of C atoms (13 g·mol -1 ).

[0060] Figure 2 The results show that the photosynthetic rate of corn leaves increases significantly from the base to the tip, with a value of 13.8-19.3 μmol·m -2 ·s -1 .

[0061] Example 3

[0062] Same as Example 3, except that an assimilation chamber is used according to Figure 1 After stopping ventilation in step 3, take out the leaves from the first assimilation leaf chamber, switch the airway to the next assimilation leaf chamber, and repeat the above operation for assimilation marking.

[0063] Example 4

[0064] To verify the present invention 13 CO 2 The reliability of the labeling method in the quantitative measurement of photosynthetic rate was tested in the following two tests. The operation steps are as follows:

[0065] 1) Assessment of assimilate transport during labeling

[0066] After 2 minutes of assimilation, the marked area and nearby areas are measured 13 The ratio of C to total C was used to evaluate the transport of assimilates. 13 If C is transferred to other parts of the blade, it will cause measurement errors.

[0067] Ten potted corn plants were used: five plants were used to evaluate the transport of assimilates at the tip of the leaf (70% of the leaf length from the ligule), and the other five plants were used to evaluate the transport of assimilates at the base of the leaf (30% of the leaf length from the ligule). The assimilation labeling operation was the same as in Example 2. After 2 minutes of assimilation labeling, leaf tissue samples were collected from the labeled area and 0-2 cm and 2-4 cm above and below it, and their 13 Before marking, five control samples should be collected from the tip and base of the leaves to determine the ratio of the control. 13 The ratio of C to total C assimilated at the labeled site 13 C quality (M label, g) and its proportion in the total amount (P label , %) were calculated by the following formulas:

[0068] M label =DW×C%×(R label -R ref ) (2)

[0069]

[0070] Where M -2 、M -1 、M 1 and M 2 The assimilation of leaf tissue at 2-4cm, 0-2cm below the marked part and 0-2cm, 2-4cm above the marked part respectively. 13 C quality. M -2 、M -1 、M 1 and M 2 It is also calculated based on formula (2).

[0071] Results Figure 3 When the distance from the ligule to 1 / 3 of the leaf length 13 CO 2 After 2 minutes of labeling, 99.3% of the newly assimilated 13 C remained at the labeled site, while less than 0.7% of the newly assimilated 13C was transported to adjacent leaf tissues. Similar results were found when labeling was performed at a distance of 2 / 3 of the leaf length from the ligule.

[0072] 2) Portable photosynthetic instrument and the present invention 13 CO 2 Comparison of photosynthetic measurement results using labeling methods

[0073] Thirteen leaves from five potted maize plants were used for this comparison. The plants were dehydrated to different drought levels, and gas exchange in the mid-region of each leaf was measured using a portable photosynthetic meter (Licor-6800; LI-COR, USA). The photon density in the leaf chamber of the portable photosynthetic meter was set to 1300 μmol·m -2 ·s -1 , air temperature, relative humidity and CO 2 The concentrations were set at 27°C, 60%, and 400 ppm. n , μmol·m -2 ·s -1 ) and stomatal conductance were stable and the results were recorded. Then, the gas supply channel of the portable photosynthetic instrument was immediately switched from ambient air to the adjusted mixed gas (400ppm 13 CO 2, 80%-20% nitrogen and oxygen), the temperature, light quantum density and relative humidity of the leaf chamber of the portable photosynthetic instrument remained unchanged. After 2.5 minutes of ventilation marking, the leaf samples in the leaf chamber were cut and their leaf mass per unit area LMA, carbon content in dry matter and 13 The ratio of C to total C, the photosynthesis rate A obtained by the calculation method of Example 2 13C .

[0074] Using Licor-6800 portable photosynthetic instrument and the present invention 13 CO 2 The photosynthetic rate of the middle part of the same leaf was compared and analyzed by the marking method. The results showed that there was a strong correlation between the photosynthetic rate values ​​measured by the two methods ( Figure 4 ; R 2 =0.95, P<0.0001), and the slope was close to 1.

[0075] The above test results show that the method for measuring the photosynthetic rate of plant leaves of the present invention is reliable.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining the photosynthetic rate of plant leaves based on carbon 13 isotope labeling, characterized in that: The plant leaves were photosynthetically induced with 13 The mixed gas of CO2 was used to assimilate the leaves after photosynthesis induction; the leaf mass per unit area LMA, the carbon content in the dry matter and the carbon content in the dry matter of the leaves after assimilation marking were measured. 13 The ratio of C to total C is used to calculate the local photosynthetic rate of leaves according to the following formula: Where C% is the carbon content in dry matter, R label Is the labeled sample 13 The ratio of C to total C, R ref In the unlabeled sample 13 The ratio of C to total C, t is the assimilation labeling time, m c yes 13 The molecular weight of the C atom.

2. The method according to claim 1, characterized in that Divide the assimilated labeled leaves into several leaf tissues and measure the area a of the leaf tissues leaf The leaf mass per unit area (LMA) was calculated from the dry weight (DW).

3. The method according to claim 1, characterized in that The leaf tissue was dried and ground into powder, and the carbon content in the leaf dry matter was measured using an elemental analyzer, and the 13 The ratio of C to total C.

4. The method according to claim 1, characterized in that: The mixed gas includes a concentration of 400-410 ppm 13 CO2 and nitrogen and oxygen, 13 The volume ratio of CO2 to nitrogen and oxygen is 1:2500, and the volume ratio of nitrogen and oxygen in the nitrogen and oxygen is 4:

1.

5. The method according to claim 4, characterized in that The flow rate of the nitrogen and oxygen is adjusted to not less than 40 L min -1 , 13 The flow rate of CO2 is adjusted according to the flow rate of nitrogen and oxygen.

6. The method according to claim 1, characterized in that The photosynthetic induction time is 20-40 minutes, and the assimilation labeling time is 2-3 minutes.

7. A device for measuring the photosynthetic rate of plant leaves based on the method according to any one of claims 1 to 6, characterized in that: It includes a gas source, a gas mixing box and an assimilation leaf chamber, wherein the gas source is 13 CO2 device and nitrogen oxygen device, the 13 The CO2 device and the nitrogen and oxygen device are connected to the gas mixing box through a pipeline equipped with a flow controller, and the gas mixing box is connected to the assimilation leaf chamber through a pipeline; one end of the assimilation leaf chamber is connected to a tail gas absorption device; a light source is arranged above the assimilation leaf chamber, and a fan is arranged inside.

8. The device according to claim 7, characterized in that The assimilation leaf chambers are made of transparent material, and are provided in plurality, all of which are connected with the gas mixing box and the tail gas absorption device through pipelines.

9. The device according to claim 7, characterized in that The assimilation leaf chamber is divided into an upper cover and a lower box body, and the lower box body is provided with a flange and a gasket to seal with the upper cover; one end of the assimilation leaf chamber is a movable opening for placing the leaf to be tested.

10. The device according to claim 7, characterized in that The tail gas absorption device is filled with NaOH solution.

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