A method for measuring the leaf area of plants

Abstract

The present invention discloses a method for measuring the leaf area of plants. By measuring the leaf area of plant leaves and the weight of the water film adsorbed on the body surface, a regression model is established. When measuring the same type of leaves subsequently, the leaf area of the plant can be quickly obtained by substituting the measured water film weight into the regression equation. The measurement method of the present invention is convenient to operate and has low cost, and is applicable to all submerged plants. It effectively solves the problems existing in the measurement of the leaf area of submerged plants due to small leaves, irregular shapes, many heteromorphic leaves, high water content in the leaves and easy deformation due to water loss, etc.

Description

Technical Field

[0001] The present invention relates to a method for measuring the leaf area of plants, and particularly to a method suitable for measuring the leaf area of submerged plants. Background Art

[0002] Most of the reported methods for measuring the leaf area of plants are applicable to terrestrial plants, and there are few reports on the methods for measuring the leaf area of submerged plants. Since submerged plants live in water for a long time, their morphological structures are significantly different from those of terrestrial plants. For example, they have a high water content (higher than 90%), underdeveloped mechanical tissues, no cutin layer or underdeveloped cutin layer on the leaf surface, and usually have characteristics such as small leaves, thin leaves, and extremely divided leaves. The commonly used methods for measuring the leaf area of terrestrial plants often have certain limitations in measuring the leaf area of submerged plants. Measuring the leaf area is often required in the research on photosynthetic carbon fixation of submerged plants, the development and evaluation of aquatic biological resources, and the health management of aquatic ecosystems.

[0003] The existing methods for measuring the leaf area of plants include: portable laser leaf area meters, traditional grid counting methods, plant leaf area measurement methods based on image processing computer technology, etc. When measuring the leaf area of submerged plants, they mainly have the following defects: 1) Portable laser leaf area meters are expensive, have high maintenance costs, and have a long maintenance time when damaged. There is a phenomenon that there is no data when the leaves are too small. The instrument itself has limitations in use, such as it cannot be used in a humid environment and is not suitable for measuring the leaf area of submerged plant leaves; 2) The traditional grid counting method for measuring leaf area or the paper-cutting and weighing method requires drawing a large number of leaf contours on paper, and the work is relatively cumbersome and time-consuming; 3) Measuring the leaf area of plants based on image processing computer technology requires certain equipment and familiarity with relevant software. Moreover, aquatic plants have a high water content and are prone to water loss and deformation. Secondly, the leaf shapes are complex (linear, sheet-like, needle-like, etc.), and this method is not suitable for measurement. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a method that can be applicable to measuring the leaf area of submerged plants.

[0005] Technical Solution: A method for measuring the leaf area of plants according to the present invention includes the following steps:

[0006] (1) Collect a plurality of plant leaves of the same type as the leaves of the plant to be measured;

[0007] (2) Put the plant leaves into acetone or ethanol to fix their shapes, take them out after complete dehydration, and weigh them;

[0008] (3) Immerse the dehydrated plant leaves in water, take them out after a water film is formed, shake off the free water on the leaf surface, and weigh them;

[0009] (4) Calculate the weight x of the water film adsorbed on the leaf based on the difference between the two weighings;

[0010] (5) Determine the plant leaf area y;

[0011] (6) Establish a regression equation between the weight x of the water film adsorbed on the leaf and the leaf area y;

[0012] (7) Measure the weight x of the water film adsorbed on the leaves of the plant to be tested according to steps (2) to (4), substitute it into the regression equation, and obtain the leaf area of ​​the plant to be tested.

[0013] Plant leaves used to establish regression equations should be selected from leaves whose leaf area is easy to calculate.

[0014] Furthermore, the frequency of shaking off the free water on the blade surface in step (3) is 10-15 times / 10 seconds.

[0015] Furthermore, when measuring the plant leaf area y in step (5), if the plant leaf to be measured is a sheet leaf, the paper-cut weighing method is used for measurement.

[0016] Furthermore, the paper-cut weighing method comprises the following steps: tracing a fixed-shape plant leaf on sulfuric acid paper, cutting it according to the drawn pattern, and weighing the cut sulfuric acid paper to obtain g1; taking a piece of sulfuric acid paper with known length and width, calculating its area s2, and weighing it to obtain g2; calculating the area s1 of the cut paper, and calculating according to the formula s1=g1 / g2*s2, the obtained s1 is the plant leaf area y.

[0017] Furthermore, when measuring the plant leaf area y in step (5), if the cross-section of the plant leaf to be measured is circular, its radius / diameter d and length h are measured, and the plant leaf area y is calculated according to the formula y=πdh.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following outstanding advantages: the measurement method of the present invention measures the same type of leaves, combines the leaf area of ​​the plant leaves and the weight of the water film adsorbed on the surface of the plant leaves, establishes a regression model, and when the leaf area of ​​the same type of leaves is subsequently measured, the measured water film weight can be substituted into the regression equation to quickly obtain the plant leaf area. The measurement method of the present invention is easy to operate, low in cost, and applicable to all submerged plants, effectively solving the problem of difficult leaf area measurement and calculation for Elodea, Dermatophyte, etc., with small leaves, irregular shapes, many special-shaped leaves, high water content, and easy deformation due to water loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a regression equation relationship diagram between the weight of water film adsorbed by Vallisneria sinensis leaves and the leaf area measured by the method of the present invention;

[0020] Figure 2Regression equation relationship diagram of the adsorbed water film weight and surface area of Hydrilla verticillata measured by the method of the present invention;

[0021] Figure 3 Regression equation relationship diagram of the adsorbed water film weight and surface area of Myriophyllum verticillatum measured by the method of the present invention. Specific embodiments

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0023] Example 1

[0024] (1) Collect the submerged plant Potamogeton crispus leaves in the pond;

[0025] (2) Randomly select Potamogeton crispus plant leaves (2-5 cm long and 0.3-1 cm wide), rinse them and place them in a sealed acetone solution for 5 minutes for dehydration and shaping, then weigh them;

[0026] (3) Immerse the weighed plant leaves in water, take them out after a water film is formed, and shake the leaves 10 times at 1 time per second. During the experiment, the water film weight changes little when shaken 10-15 times / 10 seconds. Therefore, 10 times / 10 seconds is selected for weighing;

[0027] (4) Calculate the weight x of the water film adsorbed by the leaves according to the numerical difference between the two weighings;

[0028] (5) Measure the area y of the plant leaves. Fix the leaves with the adsorbed water film weight x calculated, trace the figure on the sulfuric acid paper, cut it with scissors, weigh the cut paper on an electronic balance and record it as g1, weigh the sulfuric acid paper with known length and width and record it as g2, calculate its area and record it as s2 (s2 = length * width), and calculate the area of the cut paper according to the formula s1 = g1 / g2 * s2, which is the area of the plant leaf;

[0029] (6) Establish a regression equation between the weight x of the water film adsorbed by the leaves and the area y of the leaves, y = 279.6x - 3.8666 (R 2 = 0.9861), where x is the water film weight (g) and y is the leaf area (cm 2 );

[0030] (7) Measure the weight x of the water film adsorbed by the leaves of the plant to be measured according to steps (2)-(4), and substitute it into the regression equation to obtain the leaf area of the plant leaves to be measured.

[0031] Compare the leaf areas measured by the two methods, and the relative error is less than 6%. The results are shown in Table 1.

[0032] Table 1: Leaf areas of plants measured by the water film weighing method and the paper cutting weighing method and relative errors

[0033]

[0034] Example 2

[0035] The Vallisneria natans used was a 20-cm-tall plant purchased online. The remaining steps were the same as in Example 1. A regression equation for the weight of the adsorbed water film and the body surface area was established: y = 218.2x + 0.1082 (R 2 = 0.963). It can be seen from the regression equation that the weight of the adsorbed water film on the leaf is significantly positively correlated with the leaf body surface area. The results are shown in Figure 1 .

[0036] Example 3

[0037] The Hydrilla verticillata used was a plant grown in a laboratory culture tank. The remaining steps were the same as in Example 1. A regression equation for the weight of the adsorbed water film and the body surface area was established: y = 141.18x + 0.02742 (R 2 = 0.9565). It can be seen from the regression equation that the weight of the adsorbed water film on the leaf is significantly positively correlated with the leaf body surface area. The results are shown in Figure 2 .

[0038] Example 4

[0039] The Myriophyllum verticillatum used was taken from a nearby pond. The radius / diameter d and length h of the plant leaves were measured, and the plant leaf area y was calculated according to the formula y = πdh. The remaining steps were the same as in Example 1. A regression equation for the weight of the adsorbed water film and the body surface area was established: y = 183.62x – 0.0045 (R 2 = 0.9518). It can be seen from the regression equation that the weight of the adsorbed water film on the leaf is significantly positively correlated with the leaf body surface area. The results are shown in Figure 3 .

[0040] The above examples all show that there is a significant linear regression relationship between the weight of the adsorbed water film by plants and the surface area (R 2 > 0.95). That is, once the regression equation is established, the plant body surface area can be obtained through the weight of the adsorbed water film by plants. The method for measuring the plant leaf area provided here has low cost, flexible operation, accurate measurement, time saving, and effectively solves the problems of measuring and calculating the areas of irregular and small leaves; due to the characteristics of submerged plants, especially the small and irregularly divided leaves of most plants such as Hydrilla verticillata and Myriophyllum verticillatum, it is difficult to obtain accurate data through other methods. However, the method adopted in the present invention can accurately measure the parameters of plant leaves of any area size as long as the regression equation between the weight of the adsorbed water film by plants and the area is established and the weight of the adsorbed water film by plants is measured.

Claims

1. A method for measuring the leaf area of submerged plants, characterized in that, It includes the following steps: (1) Collect several plant leaves of the same type as the leaves of the plant to be measured; (2) Put the plant leaves into acetone or ethanol to fix their shapes, take them out after complete dehydration, and weigh them; (3) Immerse the dehydrated plant leaves in water, take them out after a water film is formed, shake off the free water on the leaf surface, and weigh them; (4) Calculate the weight x of the water film adsorbed by the leaf based on the numerical difference between the two weighings; (5) Measure the area y of the plant leaf; (6) Establish a regression equation between the weight x of the water film adsorbed by the leaf and the area y of the leaf; (7) Measure the weight x of the water film adsorbed by the leaf of the plant to be measured according to steps (2)-(4), and substitute it into the regression equation to obtain the leaf area of the leaf of the plant to be measured.

2. The method for measuring the leaf area of submerged plants according to claim 1, wherein: In step (3), the frequency of shaking off the free water on the leaf surface is 10-15 times / 10 seconds.

3. A method for measuring the leaf area of submerged plants according to claim 1, characterized in that: When measuring the area y of the plant leaf in step (5), if the leaf of the plant to be measured is a flaky leaf, the paper-cutting weighing method is used for measurement.

4. The method for measuring the leaf area of submerged plants according to claim 3, characterized in that, The steps of the paper-cutting weighing method include: tracing the figure of the plant leaf after fixing its shape on the sulfuric acid paper, cutting it according to the drawn figure, weighing the cut sulfuric acid paper to obtain g1; taking a sulfuric acid paper with known length and width, calculating its area s2, and weighing it to obtain g2; calculating the area s1 of the cut paper, and calculating according to the formula s1 = g1 / g2 * s2 to obtain s1, which is the plant leaf area y.

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