Method for identifying leaf chlorophyll spad value of pear germplasm

Abstract

The application discloses a method for identifying leaf chlorophyll SPAD value of pear germplasm, which comprises the following steps: A, investigating time step; B, investigating method step; C, determining leaf chlorophyll SPAD value of pear germplasm step; D, dividing leaf chlorophyll SPAD value identification grading standard step of pear germplasm; E, determining and grading leaf chlorophyll SPAD value of pear germplasm to be determined. The application has the following advantages and effects: after the steps of determining the investigation time and the investigation method, the determination of the leaf chlorophyll SPAD value of the pear germplasm, according to the normal distribution diagram of the measured leaf chlorophyll SPAD value of the pear germplasm, the leaf chlorophyll content identification grading standard of the pear germplasm is formulated, and the leaf chlorophyll SPAD value of the pear germplasm to be determined is determined and graded. Finally, the leaf chlorophyll content grading standard of the pear germplasm is formulated, the leaf chlorophyll content grade of the pear germplasm resource can be quickly determined through the measured leaf chlorophyll SPAD value, a scientific basis is provided for pear excellent germplasm resource excavation and pear tree production management.

Description

Technical Field

[0001] This invention relates to the field of fruit tree research technology, and in particular to a method for identifying the SPAD value of chlorophyll in pear germplasm leaves. Background Technology

[0002] Pears, as one of my country's main fruits, are rich in nutrients and characterized by their sweetness, crispness, and juiciness, making them popular among the general public. Pears belong to the subfamily Maloideae of the family Rosaceae in the class Dicotyledonous of the phylum Angiosperms. There are many varieties, and their size varies depending on the cultivar. Currently, the mainstream varieties cultivated in China include 'Cuiguan', 'Huangguan', 'Golden Pear', 'Crispy Pear', 'Korla Fragrant Pear', 'Duck Pear', 'Snowflake Pear', and 'Qiuyue Pear'. According to statistics from the Ministry of Agriculture and Rural Affairs of the People's Republic of China, my country's pear production reached 19.2653 million tons in 2022, a year-on-year increase of 2.06%, ranking first in the world. Pear production has always been an important pillar industry for increasing farmers' income and wealth in my country, and it is also one of my country's main agricultural products for export earnings.

[0003] In recent years, the detection of chlorophyll content in pear tree leaves has become increasingly important in pear tree cultivation. Measuring the chlorophyll content of pear tree leaves using a leaf chlorophyll content meter can predict pear yield and nitrogen content. Knowing the nitrogen content of pear trees allows for accurate application of nitrogen fertilizers, preventing waste and improving the profitability of pear tree cultivation to some extent. The chlorophyll content of pear tree leaves determines the efficiency of photosynthesis and has a direct or indirect relationship with the number of fruiting branches each year, the size of the fruit, and the sugar and acid content and aroma intensity of the fruit.

[0004] While chlorophyll content in pear leaves can currently be measured using instruments, effective identification and statistical methods have not been developed. This makes it impossible to effectively address the rapid identification of SPAD values ​​for pear varietal resources in pear research, breeding, and production. Furthermore, the lack of standards prevents the rapid determination of the chlorophyll content grade of pear germplasm resources by measuring SPAD values, thus hindering the provision of a scientific basis for the discovery of superior pear germplasm resources and pear tree production management. Summary of the Invention

[0005] The purpose of this invention is to provide a method for identifying the SPAD value of chlorophyll in pear germplasm leaves. By establishing standards and then measuring the SPAD value of chlorophyll in pear tree leaves, the grade of chlorophyll content in pear germplasm resources can be quickly determined, thus providing a scientific basis for the discovery of superior pear germplasm resources and the production management of pear trees.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for identifying the SPAD value of chlorophyll in pear germplasm leaves, comprising the following steps:

[0007] A: Investigation timeline steps, determine the specific time for measuring chlorophyll content in pear leaves;

[0008] B: Investigation methods and procedures, determining the sampling location and quantity of pear leaves for chlorophyll content determination;

[0009] C: Procedure for determining the SPAD value of chlorophyll in pear germplasm leaves;

[0010] D: Steps for classifying and grading the SPAD values ​​of pear germplasm leaves: Based on the normal distribution of the measured SPAD values ​​of pear germplasm leaves, classify and grade the SPAD values ​​of pear germplasm leaves according to the standards.

[0011] E: Grading of the SPAD value of chlorophyll in the leaves of the pear germplasm to be tested.

[0012] A further provision of the present invention is that step A is: after the new shoots of pear trees stop growing in early July, the chlorophyll content of mature leaves is measured.

[0013] A further provision of the present invention is as follows: Step B is as follows: 3 trees are selected for each pear germplasm sample; samples are taken from each pear tree in five directions: east, west, south, north, and center; 2 one-year-old shoots are randomly selected from the periphery of the pear tree in each direction; the 6th mature leaf from the base is selected; the leaves are required to be free from damage and disease; 2 leaves are taken from each direction; a total of 10 leaves are taken from the 5 directions; a total of 30 leaves meeting the requirements are taken from each pear germplasm sample.

[0014] A further setting of the present invention is as follows: Step C is: measuring the relative chlorophyll content of leaves using a plant nutrient analyzer, measuring 30 leaves selected from each pear germplasm once, and the average chlorophyll SPAD value of the 30 leaves is the chlorophyll SPAD value of the leaves of the pear germplasm.

[0015] A further provision of the present invention is that step D is: based on the normal distribution diagram of the chlorophyll SPAD values ​​of 1170 pear germplasm leaves measured, the chlorophyll SPAD values ​​are divided into five levels of standards: extremely low content, low content, medium content, high content, and extremely high content, using an arithmetic progression method.

[0016] Extremely low content (EL) (chlorophyll SPAD value < 43)

[0017] Low content (L) (43≤chlorophyll SPAD value<48)

[0018] Medium content (M) (48 ≤ chlorophyll SPAD value < 53)

[0019] High content (H) (53≤Chlorophyll SPAD value<58)

[0020] Extremely high content (EH) (chlorophyll SPAD value ≥58).

[0021] A further arrangement of the present invention is that: step E is as follows: according to the aforementioned steps A, B, and C, use a plant nutrient analyzer to measure the chlorophyll SPAD value of the leaves of the pear germplasm to be measured, and determine the chlorophyll SPAD value level of the leaves of this pear germplasm based on the chlorophyll SPAD value of the leaves of the pear germplasm to be measured.

[0022] A further arrangement of the present invention is that: in step C, when measuring the leaves of the 3 trees selected for each pear germplasm, first use a leaf clamping device to classify and clamp the leaves of the 3 trees, so that more than two-thirds of the leaves protrude from the clamping device, and then it is convenient to insert the leaves into the measuring part of the plant nutrient analyzer and close the measuring probe to complete the measurement during measurement;

[0023] The leaf clamping device includes a base (1), a rotating plate (2) rotatably connected to one side of the base (1) and in a horizontal state in the initial state, an angle adjustment mechanism (3) provided between the base (1) and the rotating plate (2) to realize the angle adjustment of the rotating plate (2), three fixed clamping strips (4) provided on the rotating plate (2), three moving clamping strips (5) slidably arranged on the rotating plate (2) and forming a clamping cavity with the fixed clamping strips (4) respectively, an elastic component (6) provided between the rotating plate (2) and the moving clamping strips (5) to drive the moving clamping strips (5) to move towards the direction close to the fixed clamping strips (4), and an unlocking component (7) provided between the rotating plate (2) and the three moving clamping strips (5) to simultaneously overcome the elastic force of the three elastic components (6) when the rotating plate (2) is in the initial state. Ten leaves of each tree are sequentially clamped between the same fixed clamping strip (4) and the moving clamping strip (5).

[0024] A further arrangement of the present invention is that: the angle adjustment mechanism (3) includes a plurality of limiting strips (31) arranged in a row on the base (1), and an adjusting support rod (32) rotatably connected to the back of the rotating plate (2) and in a "U" shape. The bottom of the adjusting support rod (32) abuts against one of the limiting strips (31) to realize the angle adjustment of the rotating plate (2);

[0025] The elastic component (6) includes two limiting seats (61) provided on the rotating plate (2), a limiting shaft (62) provided on the moving clamping strip (5) and passing through the limiting seat (61), and a compression spring (63) sleeved on the limiting shaft (62) and abutted between the limiting seat (61) and the moving clamping strip (5);

[0026] The moving clamping bar (5) is above the corresponding fixed clamping bar (4), and the rotating plate (2) is provided with a through hole (21) near the upper end of the limiting shaft (62); the unlocking component (7) includes a first wedge block (71) slidably connected to the back of the rotating plate (2), a plurality of steel cables (72) with one end set on the first wedge block (71) and the other end passing through the through hole (21) and connected to the upper end of the limiting shaft (62), and a second wedge block (73) set on the base (1). In the final stage of the process of the rotating plate (2) rotating to the initial state, the first wedge block (71) and the second wedge block (73) gradually press against each other to overcome the elastic force of the plurality of compression springs (63).

[0027] The beneficial effects of this invention are:

[0028] 1. After determining the investigation time and adjustment methods, the SPAD value of chlorophyll in the leaves of each pear germplasm was measured. Based on the normal distribution of the measured SPAD values, a grading standard for the SPAD value of pear germplasm leaves was established to achieve the grading of the SPAD value of the pear germplasm leaves to be measured. Ultimately, by establishing the standard, the measurement of the SPAD value of pear leaves can quickly determine the grade of chlorophyll content in pear germplasm resources, thus providing a scientific basis for the discovery of superior pear germplasm resources and the management of pear tree production.

[0029] 2. Based on the normal distribution of the measured SPAD values ​​of pear germplasm leaves, the content is divided into five levels: extremely low, low, medium, high, and extremely high, using the arithmetic progression method. In step E, following steps A, B, and C, the leaves of the pear germplasm to be tested are taken, and the SPAD values ​​of the leaves are measured using a plant nutrient analyzer. The measured SPAD values ​​of the leaves can quickly determine the level of chlorophyll content in the leaves of the pear germplasm resource.

[0030] 3. When measuring the mature leaves of 3 selected pear trees for each sample, the leaves of the 3 trees are first classified and clamped using a leaf clamping device, so that more than two-thirds of the leaf protrudes from the clamping device. Then, during measurement, the leaf can be easily inserted into the measuring part of the plant nutrient analyzer and the measuring probe can be closed to complete the measurement. At the same time, when using the leaf clamping device, the unlocking component in the initial state can overcome the elastic force of the elastic component, so that the moving clamping bar and the fixed clamping bar can be separated, making it easy for the leaf to be partially embedded in the clamping cavity between the fixed clamping bar and the moving clamping bar. When the rotating plate is rotated, the rotating plate is disengaged from the initial state. At this time, the elastic component quickly drives the moving clamping bar to move to clamp the leaf. Finally, after the rotating plate rotates upward, it is convenient for the plant nutrient analyzer to perform the measurement. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a normal distribution diagram of the SPAD values ​​of chlorophyll in pear germplasm leaves in step D of Example 1;

[0033] Figure 2 This is a scatter plot of chlorophyll SPAD values ​​in leaves of different pear varieties in Example 1, Demonstration 2;

[0034] Figure 3 This is a bar chart showing the number of pear germplasms with different leaf chlorophyll SPAD values ​​for identification grades in Example 1, Certificate 2.

[0035] Figure 4 This is a side view of the blade clamping device in Embodiment 2.

[0036] In the diagram: 1. Base; 2. Rotating plate; 21. Through hole; 3. Angle adjustment mechanism; 31. Limiting strip; 32. Adjusting support rod; 4. Fixed clamping strip; 5. Moving clamping strip; 6. Elastic component; 61. Limiting seat; 62. Limiting shaft; 63. Compression spring; 7. Unlocking component; 71. First wedge block; 72. Steel cable; 73. Second wedge block. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] Example 1: A method for identifying the SPAD value of chlorophyll in pear germplasm leaves, the steps of which are as follows:

[0039] A: Investigation timeline and steps

[0040] The specific time for measuring the chlorophyll content of pear leaves was determined. Specifically, the chlorophyll content of leaves from pear germplasm resources preserved at the National Sand Pear Germplasm Resource Nursery (Wuhan) was measured in early July, after the new shoots of pear trees had stopped growing.

[0041] B: Survey Methods and Procedures

[0042] Determine the sampling location and quantity of pear leaves for chlorophyll content determination. Select 3 trees for each pear germplasm. For each pear tree, samples are taken from five directions: east, west, south, north, and center. For each direction, randomly select 2 one-year-old shoots from the outer periphery of the pear tree and select the 6th mature leaf from the base. The leaves should be free of damage and disease. Take 2 leaves from each direction, for a total of 10 leaves from the 5 directions. A total of 30 leaves meeting the requirements are collected for each pear germplasm.

[0043] C: Procedure for determining the SPAD value of chlorophyll in pear germplasm leaves

[0044] The relative chlorophyll content of leaves was measured using a TYS-3N plant nutrient analyzer produced by Zhejiang Top Cloud Agriculture Technology Co., Ltd. 30 leaves were selected from each pear germplasm and measured once. The average chlorophyll SPAD value of the 30 leaves was the chlorophyll SPAD value of the pear germplasm.

[0045] D: Steps for classifying and grading pear germplasm leaf chlorophyll SPAD values ​​according to standards.

[0046] Based on the normal distribution diagram of chlorophyll SPAD values ​​in leaves of 1170 pear germplasms (as shown in the figure) Figure 1 As shown in the figure, the classification and grading standards for SPAD values ​​of pear germplasm leaves are as follows. Specifically, they are divided into five levels using an arithmetic progression method: extremely low content, low content, medium content, high content, and extremely high content.

[0047] Extremely low content (EL) (chlorophyll SPAD value < 43)

[0048] Low content (L) (43≤chlorophyll SPAD value<48)

[0049] Medium content (M) (48 ≤ chlorophyll SPAD value < 53)

[0050] High content (H) (53≤Chlorophyll SPAD value<58)

[0051] Extremely high content (EH) (chlorophyll SPAD value ≥58).

[0052] E: Grading of chlorophyll SPAD values ​​in leaves of pear germplasm to be tested

[0053] Following steps A, B, and C as described above, the SPAD value of chlorophyll in the leaves of the pear germplasm to be tested was measured using a TYS-3N plant nutrient analyzer manufactured by Zhejiang Top Cloud Agriculture Technology Co., Ltd. The SPAD value level of the pear germplasm leaves was determined based on the SPAD value of the leaves.

[0054] Example 1: Specifically, taking the leaves of the 'Jinmi' pear as an example, the steps for identifying the chlorophyll content of the 'Jinmi' pear leaves are as follows:

[0055] A: Leaf sampling

[0056] On July 8, 2023, at around 10:00 AM, three 'Jinmi' pear trees were selected. Samples were taken from five directions: east, west, south, north, and center. Two one-year-old shoots were randomly selected from the outer periphery of the pear tree from each direction. The sixth mature leaf from the base of the shoot was selected. The leaves were required to be free from damage and disease. Two leaves were taken from each direction, for a total of 10 leaves from the five directions. A total of 30 leaves meeting the requirements were taken from each pear germplasm.

[0057] B: Measuring the SPAD value of chlorophyll in 'Golden Honey' pear leaves

[0058] The relative chlorophyll content of leaves was measured using a TYS-3N plant nutrient analyzer produced by Zhejiang Top Cloud Agriculture Technology Co., Ltd. Thirty leaves of the 'Jinmi' pear variety were selected and measured once each. The average chlorophyll SPAD value of the 30 leaves of the 'Jinmi' pear variety was calculated to be 49.9.

[0059] C: Determining the grade of chlorophyll content in pear germplasm leaves

[0060] According to the identification and grading standard of chlorophyll SPAD value of pear germplasm leaves, the average chlorophyll SPAD value of 'Jinmi' pear leaves is between 48 and 53, and the chlorophyll content of 'Jinmi' pear leaves is judged to be of medium content.

[0061] Implementation results: The chlorophyll content level of 'Jinmi' pear leaves can be quickly determined based on the SPAD value of chlorophyll, thus providing a scientific basis for the discovery of superior pear germplasm resources and the production management of pear trees.

[0062] Example 2: The chlorophyll SPAD value identification data of leaves from other germplasms (a total of 585 samples) in the National Sand Pear Germplasm Resource Garden (Wuhan) were used to evaluate the chlorophyll content level of the leaves.

[0063] like Figure 2 and Figure 3 It can be seen that by using this method to identify the SPAD values ​​of chlorophyll in leaves of other germplasm resources (a total of 585) in the National Sand Pear Germplasm Resource Nursery (Wuhan), 42 varieties with extremely low chlorophyll content, 136 varieties with low content, 233 varieties with medium content, 153 varieties with high content, and 21 varieties with extremely high content were screened out, thus achieving the goal of providing a scientific basis for the discovery of superior pear germplasm resources and the production management of pear trees.

[0064] Example 2: Figure 4As shown, the leaf clamping device includes a base 1, a rotating plate 2 rotatably connected to the base 1 on one side and initially horizontal, an angle adjustment mechanism 3 disposed between the base 1 and the rotating plate 2 to adjust the angle of the rotating plate 2, three fixed clamping bars 4 disposed on the rotating plate 2, three movable clamping bars 5 slidably disposed on the rotating plate 2 and forming clamping cavities with the fixed clamping bars 4 respectively, an elastic component 6 disposed between the rotating plate 2 and the movable clamping bars 5 to drive the movable clamping bars 5 to move toward the fixed clamping bars 4, and an unlocking component 7 disposed between the rotating plate 2 and the three movable clamping bars 5 to simultaneously overcome the elastic force of the three elastic components 6 when the rotating plate 2 is in the initial state. Ten leaves of each tree are sequentially clamped between the same fixed clamping bar 4 and the movable clamping bar 5.

[0065] like Figure 2 As shown, the angle adjustment mechanism 3 includes multiple limiting bars 31 arranged on the base 1, and an adjustment support rod 32 rotatably connected to the back of the rotating plate 2 in a U-shape. The bottom of the adjustment support rod 32 abuts against one of the limiting bars 31 to adjust the angle of the rotating plate 2. The elastic component 6 includes two limiting seats 61 arranged on the rotating plate 2, a limiting shaft 62 arranged on the movable clamping bar 5 and passing through the limiting seats 61, and a compression spring 63 sleeved on the limiting shaft 62 and pressed between the limiting seats 61 and the movable clamping bar 5. The movable clamping bar 5 is above the corresponding fixed clamping bar 4. The rotating plate 2 is provided with a through hole 21 near the upper end of the limiting shaft 62. The unlocking component 7 includes a first wedge block 71 slidably connected to the back of the rotating plate 2, a plurality of steel cables 72 with one end set on the first wedge block 71 and the other end passing through the through hole 21 and connected to the upper end of the limiting shaft 62, and a second wedge block 73 set on the base 1. In the final stage of the process of the rotating plate 2 rotating to the initial state, the first wedge block 71 and the second wedge block 73 gradually press against each other to overcome the elastic force of the plurality of compression springs 63.

[0066] Implementation Results: When measuring the leaves of three randomly selected pear trees from each pear germplasm sample, a leaf clamping device was first used to classify and clamp the leaves of the three trees, ensuring that more than two-thirds of the leaf protruded from the clamping device. This allowed for easy insertion of the leaf into the measuring section of the plant nutrient analyzer, followed by closing the measuring probe to complete the measurement. Simultaneously, when using the leaf clamping device, the unlocking component 7 in the initial state overcomes the elastic force of the elastic component 6, allowing the moving clamping strip 5 and the fixed clamping strip 4 to separate. This facilitates partial embedding of the leaf into the clamping cavity between the fixed clamping strip 4 and the moving clamping strip 5. When the rotating plate 2 is rotated, it disengages from its initial state, causing the elastic component 6 to quickly drive the moving clamping strip 5 to move and clamp the leaf. Finally, after the rotating plate 2 rotates upwards, the plant nutrient analyzer can easily perform the measurement.

Claims

1. A method for identifying the SPAD value of chlorophyll in pear germplasm leaves, characterized in that: Includes the following steps: A: Investigation timeline steps, determine the specific time for measuring chlorophyll content in pear leaves; B: Investigation methods and procedures, determining the sampling location and quantity of pear leaves for chlorophyll content determination; C: Procedure for determining the SPAD value of chlorophyll in pear germplasm leaves; D: Steps for classifying and grading the SPAD values ​​of pear germplasm leaves: Based on the normal distribution of the measured SPAD values ​​of pear germplasm leaves, classify and grade the SPAD values ​​of pear germplasm leaves according to the standards. E: Grading of SPAD values ​​of chlorophyll in leaves of pear germplasm to be tested; Step C is as follows: The relative chlorophyll content of the leaves is measured using a plant nutrient analyzer. Each of the 30 leaves selected from each pear germplasm is measured once, and the average chlorophyll SPAD value of the 30 leaves is the chlorophyll SPAD value of the leaves of the pear germplasm. In step C, when measuring the leaves of the three trees selected for each pear germplasm, the leaves of the three trees are first classified and clamped using a leaf clamping device, so that more than two-thirds of the leaves protrude from the clamping device. Then, during measurement, the leaves are easily inserted into the measuring part of the plant nutrient analyzer, and the measuring probe is closed to complete the measurement. The leaf clamping device includes a base (1), a rotating plate (2) rotatably connected to the base (1) on one side and initially in a horizontal state, an angle adjustment mechanism (3) set between the base (1) and the rotating plate (2) to adjust the angle of the rotating plate (2), and three angle adjustment mechanisms (3) set on the rotating plate (1). 2) The fixed clamping bar (4) on the rotating plate (2), three movable clamping bars (5) which are slidably arranged on the rotating plate (2) and form clamping cavities with the fixed clamping bar (4) respectively, the elastic component (6) which is arranged between the rotating plate (2) and the movable clamping bar (5) and drives the movable clamping bar (5) to move toward the fixed clamping bar (4), and the unlocking component (7) which is arranged between the rotating plate (2) and the three movable clamping bars (5) and realizes the simultaneous overcoming of the elastic force of the three elastic components (6) when the rotating plate (2) is in the initial state, and the 10 leaves of each tree are clamped between the same fixed clamping bar (4) and the movable clamping bar (5) in sequence; The angle adjustment mechanism (3) includes multiple limiting strips (31) arranged on the base (1), and an adjustment support rod (32) rotatably connected to the back of the rotating plate (2) and in the shape of a "U". The bottom of the adjustment support rod (32) abuts against one of the limiting strips (31) to adjust the angle of the rotating plate (2). The elastic component (6) includes two limiting seats (61) arranged on the rotating plate (2), a limiting shaft (62) arranged on the moving clamping strip (5) and passing through the limiting seat (61), and a compression spring (63) sleeved on the limiting shaft (62) and pressed against the limiting seat (61) and the moving clamping strip (5). The moving clamping strip ( 5) Above the corresponding fixed clamping bar (4), the rotating plate (2) is provided with a through hole (21) near the upper end of the limiting shaft (62); the unlocking component (7) includes a first wedge block (71) slidably connected to the back of the rotating plate (2), a plurality of steel cables (72) with one end set on the first wedge block (71) and the other end passing through the through hole (21) and connected to the upper end of the limiting shaft (62), and a second wedge block (73) set on the base (1). In the final stage of the process of the rotating plate (2) rotating to the initial state, the first wedge block (71) and the second wedge block (73) gradually press against each other to overcome the elastic force of the plurality of compression springs (63).

2. The method for identifying the SPAD value of chlorophyll in pear germplasm leaves according to claim 1, characterized in that: Step A is as follows: After the new shoots of pear trees stop growing in early July, the chlorophyll content of mature leaves is measured.

3. The method for identifying the SPAD value of chlorophyll in pear germplasm leaves according to claim 1, characterized in that: Step B is as follows: Select 3 trees for each pear germplasm sample; take samples from each pear tree in five directions: east, west, south, north, and center; randomly select 2 one-year-old shoots from the outer periphery of the pear tree in each direction; select the 6th mature leaf from the base of the shoot; the leaves should be free of damage and disease; take 2 leaves from each direction, and take a total of 10 leaves from the 5 directions; take a total of 30 leaves that meet the requirements for each pear germplasm sample.

4. The method for identifying the SPAD value of chlorophyll in pear germplasm leaves according to claim 1, characterized in that: Step D involves: 1170 pear germplasm leaf samples are tested. Based on the normal distribution of the measured SPAD values ​​of the 1170 pear germplasm leaf samples, they are divided into five levels of standards using an arithmetic progression method: extremely low content, low content, medium content, high content, and extremely high content. Extremely low chlorophyll content (EL) SPAD value < 43 Low content (L) 43 ≤ chlorophyll SPAD value < 48 Medium content (M) 48 ≤ chlorophyll SPAD value < 53 High content (H) 53 ≤ chlorophyll SPAD value < 58 Extremely high chlorophyll content (EH) SPAD value ≥58.

5. The method for identifying the SPAD value of chlorophyll in pear germplasm leaves according to claim 4, characterized in that: Step E is as follows: following the steps A, B, and C above, the chlorophyll SPAD value of the leaves of the pear germplasm to be tested is measured using a plant nutrient analyzer, and the chlorophyll SPAD value level of the leaves of the pear germplasm to be tested is determined based on the chlorophyll SPAD value of the leaves of the pear germplasm to be tested.

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