Method for evaluating leaf removal of sugarcane by using stem sheath allometry and the content of propylendial in leaf sheath

Abstract

The application discloses a method for evaluating sugarcane leaf shedding by using stem sheath allometric growth and exodermis malondialdehyde content, and relates to the technical field of sugarcane leaf shedding evaluation. The specific steps are as follows: (1) taking the leaf sheath diameter, the internode diameter, the leaf sheath inclination angle and the exodermis malondialdehyde as evaluation indexes; (2) observing the evaluation indexes; and (3) according to the observation results of the evaluation indexes, the sugarcane is divided into an automatic leaf shedding type variety, a difficult leaf peeling type variety and an easy leaf shedding type variety. According to the characteristics that the looseness of the leaf sheath wrapped stem, the inclination angle of the leaf sheath and the deformation growth degree of the exodermis make great contributions to the leaf shedding of the sugarcane, the leaf sheath diameter, the internode diameter, the leaf sheath inclination angle and the exodermis malondialdehyde are innovatively used as the evaluation indexes to comprehensively evaluate the leaf shedding of the sugarcane, the evaluation indexes are scientific and reasonable, and the evaluation result is accurate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of evaluation of sugarcane leaf-shedding, and particularly relates to a method for evaluating leaf-shedding of sugarcane by using stem sheath heteroauxetic growth and abscission layer malondialdehyde content. BACKGROUND

[0002] Sugarcane is a natural leaf-shedding grass sugar crop. China is a large sugarcane producer, but the cost of sugarcane production is relatively high, especially the two factors of large amount of leaf stripping labor and poor quality of raw sugarcane caused by the difficulty of leaf shedding of existing sugarcane varieties, which have become important limiting factors for the efficient and sustainable development of the sugarcane industry. Sugarcane leaf stripping has always been a problem affecting the production of sugarcane in China. According to estimates, the amount of labor for leaf stripping accounts for more than 60% of the total amount of labor for harvesting. China has always been through artificial or mechanical leaf shedding of raw sugarcane before being pulled into the sugar factory for pressing processing. This approach does indeed improve the quality of raw sugarcane and reduce sugar loss during processing, but it also reduces the enthusiasm of sugarcane farmers to some extent and poses a serious obstacle to the sustainable development of the sugar industry. Therefore, whether it is manual harvesting or mechanized harvesting, improving and utilizing sugarcane varieties with good leaf-shedding performance or developing simple leaf-shedding technical measures are of great significance in reducing the cost of sugarcane harvesting and improving the quality of sugar production.

[0003] Current research mainly uses natural leaf fall rate, leaf angle and leaf shedding force to quantitatively evaluate the leaf-shedding type of sugarcane. Patent application No. 201510727814.X discloses an evaluation index screening and evaluation method for leaf-shedding of sugarcane. This method uses total node number, automatic leaf shedding node number, leaf shedding rate, stem diameter, split length, split angle, leaf shedding force and average leaf shedding force per leaf as index traits related to leaf-shedding of sugarcane, uses case ranking and factor analysis to finally determine that split length, split angle, leaf shedding force or average leaf shedding force per leaf are the rapid evaluation index traits of leaf-shedding of sugarcane, and evaluates the leaf-shedding of sugarcane varieties by establishing a discriminant function. This evaluation method can quantitatively evaluate the leaf-shedding of sugarcane, but the evaluation method is relatively complex, and the measurement of leaf shedding force is easily affected by external factors, the measurement results are unstable, and the evaluation results are easily affected. Therefore, there is an urgent need to provide a simple and accurate evaluation method.

[0004] The applicant takes the difference of sugarcane leaf shedding form and main senescence product between different genotypes as the research focus, and finds through years of research that: the base of some sugarcane varieties has been separated from the sheath, but the sheath still wraps the cane stalk, and it needs certain external force to make it separate, so the sugarcane can only fall off after completing the two links of sheath-stalk separation and abscission layer fracture under the condition of sheath wrapping the cane stalk, that is, the leaf shedding appearance of sugarcane is mainly related to the looseness of sheath wrapping cane stalk, the inclination angle of sheath and the deformation growth degree of abscission zone, therefore, the application proposes to take the looseness of sheath wrapping cane stalk, the inclination angle of sheath and the deformation growth degree of abscission zone as evaluation indexes for comprehensive evaluation, which can best reflect the leaf shedding of different sugarcane, and the evaluation method is simple and the evaluation result is accurate. SUMMARY

[0005] In view of the above problems, the technical problem to be solved by the present application is to provide a method for evaluating sugarcane leaf shedding by using stem-sheath differential growth and abscission layer malondialdehyde content, which innovatively uses sheath diameter, internode diameter, sheath inclination angle and abscission layer malondialdehyde as evaluation indexes to comprehensively evaluate the leaf shedding of sugarcane, and the evaluation indexes are scientific and reasonable, and the evaluation result is accurate. The specific technical scheme is as follows:

[0006] The method for evaluating sugarcane leaf shedding by using stem-sheath differential growth and abscission layer malondialdehyde content comprises the following steps:

[0007] (1) taking sheath diameter, internode diameter, sheath inclination angle and abscission layer malondialdehyde as evaluation indexes;

[0008] (2) observing the evaluation indexes;

[0009] (3) according to the observation results of the evaluation indexes, the sugarcane is divided into automatic leaf shedding type varieties, difficult leaf stripping type varieties and easy leaf shedding type varieties; wherein,

[0010] the automatic leaf shedding type varieties are: sheath diameter < internode diameter, and the sheath does not wrap the cane stalk; the sheath inclination angle > 0°, that is, the upper sheath separates from the cane stalk to form an open angle; the abscission layer malondialdehyde content > 17 nmol / g, and the sheath base has open-chain dissolution, which can automatically fall off;

[0011] the easy leaf shedding type varieties are: sheath diameter > internode diameter, and the sheath wraps but does not tightly adhere to the cane stalk; the sheath inclination angle = 0°, that is, the upper sheath does not separate from the cane stalk, and does not form an open angle; the abscission layer malondialdehyde content is 10-17 nmol / g, and the sheath base has open-chain dissolution, but will not automatically fall off, and the whole sheath hangs on the cane stalk after dissolution;

[0012] the difficult leaf stripping type varieties are: sheath diameter = internode diameter, and the sheath wraps and tightly adheres to the cane stalk; the sheath inclination angle = 0°, that is, the upper sheath does not separate from the cane stalk, and does not form an open angle; the abscission layer malondialdehyde content < 10 nmol / g, and the sheath base has no open-chain dissolution.

[0013] Preferably, the observation period of the evaluation index is the mature period.

[0014] Preferably, the leaf for measuring the sheath diameter and the internode diameter is any one of +7 leaves to +10 leaves.

[0015] Preferably, the leaf for measuring the sheath inclination angle is +9 leaves or +10 leaves.

[0016] Preferably, the leaf for measuring the leaf abscission layer malondialdehyde is +9 leaves or +10 leaves.

[0017] Preferably, the leaf for observing the sheath base solubility break is +9 leaves or +10 leaves.

[0018] Preferably, the leaf position is that the leaf at the connection between the sheath and the leaf at the tail of the sugarcane is +1 leaf, and the leaf position is sequentially set as +2 leaves, +3 leaves, +4 leaves, +5 leaves to +10 leaves from the base of the sugarcane.

[0019] Preferably, the leaf abscission layer malondialdehyde is the average of the malondialdehyde content of the edge, the side and the central axis of the sheath base.

[0020] Preferably, the sheath base open-chain solubility break time of the easy-to-detach leaf type variety is later than that of the automatic leaf detachment type variety.

[0021] Compared with the prior art, the beneficial effects of the present application are:

[0022] 1. The looseness of the sheath wrapped stem, the inclination angle of the sheath and the deformation growth degree of the abscission zone have the largest contribution rate to the leaf detachment of sugarcane, and they are collectively used to evaluate the leaf detachment of sugarcane. Among them, the sheath diameter and the internode diameter directly reflect the looseness of the sheath wrapped stem. When the sheath diameter is less than the internode diameter, the sheath does not wrap the cane stem; when the sheath diameter is equal to the internode diameter, the sheath wraps and closely adheres to the cane stem; and when the sheath diameter is greater than the internode diameter, the sheath wraps but does not closely adhere to the cane stem. The malondialdehyde content of the abscission layer directly reflects the deformation growth degree of the sheath base abscission zone. When the malondialdehyde content of the abscission layer is high, the sheath base has an open-chain solubility break and can automatically fall off. When the malondialdehyde content of the abscission layer is low, the sheath base has no open-chain solubility break and needs a large external force to detach the leaf. When the malondialdehyde content of the abscission layer is between the two, the sheath base has an open-chain solubility break but does not automatically fall off and still needs a certain external force to assist in detaching the leaf. Therefore, the present application innovatively uses the sheath diameter, the internode diameter, the sheath inclination angle and the malondialdehyde of the abscission layer as evaluation indexes to comprehensively evaluate the leaf detachment of sugarcane. Compared with the prior art, the evaluation indexes are more scientific and reasonable, and the accuracy of the evaluation results can be effectively improved.

[0023] 2. The method has high chemical stability of the interlayer malondialdehyde, good reproducibility between detection samples, low test cost, high efficiency, and avoids the problem that the evaluation result is not accurate due to that the index measurement is easily affected by the external environment. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are the orientations or positional relationships shown for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0026] In the description of the present application, the meaning of "several" is one or more, and the meaning of "multiple" is two or more. Greater than, less than, more than, etc. are understood as not including the number itself. Above, below, within, etc. are understood as including the number itself. If the terms "first", "second", "third" are described, they are only for the purpose of description and distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0027] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] Embodiment 1

[0029] The method for evaluating the leaf removal of sugarcane by using stem sheath allometric growth and interlayer malondialdehyde content comprises the following steps:

[0030] (1) Taking the leaf sheath diameter, internode diameter, leaf sheath inclination angle and interlayer malondialdehyde as evaluation indexes.

[0031] (2) Evaluation indicators were observed at maturity. The leaves used for measuring leaf sheath diameter and internode diameter were designated as +7 leaves; the leaves used for measuring leaf sheath tilt angle were designated as +9 leaves; the leaves used for measuring malondialdehyde (MDA) abscission layer were designated as +9 leaves; and the leaves used for observing leaf sheath base disintegration were designated as +9 leaves. The leaf positions were as follows: the leaf at the junction of the leaf sheath and leaf at the sugarcane tip was designated as +1 leaf, and towards the sugarcane base, each node was designated as +2, +3, +4, +5, up to +10 leaves. MDA abscission layer was measured as the average MDA content in the edge, side, and central axis of the leaf sheath base. Thirty individual plants of each variety were randomly selected to measure each indicator, and the average value was taken.

[0032] (3) Based on the observation results of the evaluation indicators, sugarcane was divided into three types: automatic leaf-removing varieties, difficult-to-remove-leaf varieties, and easy-to-remove-leaf varieties; among them,

[0033] Automatic leaf-shedding varieties are characterized by: leaf sheath diameter < internode diameter, leaf sheath not wrapping the sugarcane stalk; leaf sheath tilt angle > 0°, i.e., the upper leaf sheath detaches from the sugarcane stalk, forming an open angle; abscission layer malondialdehyde content > 17 nmol / g, and leaf sheath base with open-chain dissolution, enabling automatic detachment;

[0034] Easy-leaf-shedding varieties: leaf sheath diameter > internode diameter, leaf sheath wraps around but does not tightly adhere to the sugarcane stalk; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stalk and does not form an open angle; abscission layer malondialdehyde content is 10 nmol / g, leaf sheath base has open-chain dissolution, but does not fall off automatically, after dissolution, the entire leaf sheath hangs on the sugarcane stalk, the open-chain dissolution time of the leaf sheath base is later than that of the automatic-leaf-shedding varieties.

[0035] The difficult-to-peel leaf type varieties are characterized by: leaf sheath diameter = internode diameter, leaf sheath wrapping and tightly adhering to the sugarcane stem; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stem and does not form an open angle; malondialdehyde content of the abscission layer <10 nmol / g, and no open-chain melting at the leaf sheath base.

[0036] Example 2

[0037] A method for evaluating sugarcane defoliation using allometric growth of the stem sheath and malondialdehyde (MDA) content in the abscission layer includes the following steps:

[0038] (1) Leaf sheath diameter, internode diameter, leaf sheath tilt angle and malondialdehyde in the abscission layer are used as evaluation indicators.

[0039] (2) Evaluation indicators were observed at maturity. The leaves used for leaf sheath diameter and internode diameter measurements were designated as +10 leaves; the leaves used for leaf sheath tilt angle measurements were designated as +10 leaves; the leaves used for abscission malondialdehyde (MDA) measurements were designated as +10 leaves; and the leaves used for leaf sheath base disintegration measurements were designated as +10 leaves. The leaf positions were as follows: the leaf at the junction of the leaf sheath and leaf at the sugarcane tip was designated as +1 leaf, and towards the sugarcane base, each node was designated as +2, +3, +4, +5, up to +10 leaves. Abscission malondialdehyde (MDA) was the average value of MDA content measured at the edge, side, and central axis of the leaf sheath base. Thirty individual plants of each variety were randomly selected to measure each indicator, and the average value was taken.

[0040] (3) Based on the observation results of the evaluation indicators, sugarcane was divided into three types: automatic leaf-removing varieties, difficult-to-remove-leaf varieties, and easy-to-remove-leaf varieties; among them,

[0041] Automatic leaf-shedding varieties are characterized by: leaf sheath diameter < internode diameter, leaf sheath not wrapping the sugarcane stalk; leaf sheath tilt angle > 0°, i.e., the upper leaf sheath detaches from the sugarcane stalk, forming an open angle; abscission layer malondialdehyde content > 17 nmol / g, and leaf sheath base with open-chain dissolution, enabling automatic detachment;

[0042] Easy-leaf-shedding varieties: leaf sheath diameter > internode diameter, leaf sheath wraps around but does not tightly adhere to the sugarcane stalk; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stalk and does not form an open angle; abscission layer malondialdehyde content is 17 nmol / g, leaf sheath base has open-chain dissolution, but does not fall off automatically, after dissolution, the entire leaf sheath hangs on the sugarcane stalk, the open-chain dissolution time of the leaf sheath base is later than that of the automatic leaf-shedding varieties.

[0043] The difficult-to-peel leaf type varieties are characterized by: leaf sheath diameter = internode diameter, leaf sheath wrapping and tightly adhering to the sugarcane stem; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stem and does not form an open angle; malondialdehyde content of the abscission layer <10 nmol / g, and no open-chain melting at the leaf sheath base.

[0044] Example 3

[0045] A method for evaluating sugarcane defoliation using allometric growth of the stem sheath and malondialdehyde (MDA) content in the abscission layer includes the following steps:

[0046] (1) Leaf sheath diameter, internode diameter, leaf sheath tilt angle and malondialdehyde in the abscission layer are used as evaluation indicators.

[0047] (2) Evaluation indicators were observed at maturity. The leaves used for measuring leaf sheath diameter and internode diameter were designated as +9 leaves; the leaves used for measuring leaf sheath tilt angle were designated as +10 leaves; the leaves used for measuring malondialdehyde (MDA) abscission layer were designated as +10 leaves; and the leaves used for observing leaf sheath base disintegration were designated as +10 leaves. The leaf positions were as follows: the leaf at the junction of the leaf sheath and leaf at the sugarcane tip was designated as +1 leaf, and towards the sugarcane base, each node was designated as +2, +3, +4, +5, up to +10 leaves. MDA abscission layer was measured as the average MDA content in the edge, side, and central axis of the leaf sheath base. Thirty individual plants of each variety were randomly selected to measure each indicator, and the average value was taken.

[0048] (3) Based on the observation results of the evaluation indicators, sugarcane was divided into three types: automatic leaf-removing varieties, difficult-to-remove-leaf varieties, and easy-to-remove-leaf varieties; among them,

[0049] Automatic leaf-shedding varieties are characterized by: leaf sheath diameter < internode diameter, leaf sheath not wrapping the sugarcane stalk; leaf sheath tilt angle > 0°, i.e., the upper leaf sheath detaches from the sugarcane stalk, forming an open angle; abscission layer malondialdehyde content > 17 nmol / g, and leaf sheath base with open-chain dissolution, enabling automatic detachment;

[0050] Easy-leaf-shedding varieties: leaf sheath diameter > internode diameter, leaf sheath wraps around but does not tightly adhere to the sugarcane stalk; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stalk and does not form an open angle; abscission layer malondialdehyde content is 15 nmol / g, leaf sheath base has open-chain dissolution, but does not fall off automatically, after dissolution, the entire leaf sheath hangs on the sugarcane stalk, the leaf sheath base open-chain dissolution time is later than that of automatic-leaf-shedding varieties.

[0051] The difficult-to-peel leaf type varieties are characterized by: leaf sheath diameter = internode diameter, leaf sheath wrapping and tightly adhering to the sugarcane stem; leaf sheath tilt angle = 0°, that is, the upper leaf sheath does not detach from the sugarcane stem and does not form an open angle; malondialdehyde content of the abscission layer <10 nmol / g, and no open-chain melting at the leaf sheath base.

[0052] The applicant selected leaf sheath diameter, internode diameter, leaf sheath tilt angle, and malondialdehyde (MDA) abscission layer as evaluation indicators for the following reasons:

[0053] Sugarcane varieties GT47, GT60, and ROC22, which exhibit significant differences in defoliation characteristics, were used as research materials. GT47 is characterized by extremely difficult defoliation; mature leaves tightly wrap around the stalk, making them difficult to detach even with considerable external force. ROC22 is characterized by easy defoliation; mature leaves form a clear angle with the stalk, requiring considerable external force to detach completely. GT60 is characterized by extremely easy defoliation; mature green leaves form a large angle with the stalk, allowing for complete leaf detachment with relatively little external force. The sugarcane varieties were planted in February 2021 at the experimental base of the Sugarcane Research Institute of the Guangxi Academy of Agricultural Sciences (Xixiangtang District, Nanning City). The experiment followed a completely randomized block design with single-factor treatment, three replicates, and a plot area of ​​42 m². 2 Rows are 7m long and 1.2m wide, with 5 rows per area. The seeding rate is 8000 buds / 667m².2 , conventional field management. In October 2021 and 2022, phenotypic observation was conducted on the leaves and stalks of the test sugarcane varieties. The indicators included in vitro phenotypic observation of leaf sheath base, and the observation items included: leaf length, leaf width, leaf sheath length, leaf sheath width, leaf sheath length, leaf sheath thickness, leaf weight, leaf sheath weight, leaf sheath inclination, green leaf weight, dead leaf weight, total number of stalk nodes, number of dead leaf nodes, etc. The microstructure of the leaf sheath was observed under 40x optical microscope, and the Image-Pro Plus 6.0 analysis software was used to measure the air cavity area, leaf sheath thickness, red staining area and corresponding tissue area in the picture. Metabolic products and physiological substances indicators include: cellulose, hemicellulose, lignin, peroxidase (POD), malondialdehyde (MDA), 4-glucanase activity. The test data was processed by Excel 2010, and the results of metabolic product and physiological substance detection and analysis at the base of the leaf sheath were comprehensively analyzed by DPS statistical analysis software, as follows:

[0054] (1) In terms of leaf and stem morphology, the mature leaf sheath of GT47 tightly wrapped the stalk, with no stalk exposed, the separation zone was flat and regular, the upper edge and lower edge were parallel, the separation zone edge had been fused, but the fusion area was short, and the brown area of +3 to +7 leaves was small. The mature leaf sheath of ROC22 wrapped the stalk slightly looser than GT47, with part of the stalk exposed, the separation zone had a longer fusion opening area, the mature fusion separation zone edge and lower edge formed a relatively obvious angle, the immature fusion separation zone upper edge and lower edge were basically parallel, and the brown area of +3 to +7 leaves was slightly larger. The mature leaf sheath of GT60 wrapped the stalk very loosely, with most of the stalk exposed, the separation zone had a longer fusion opening than GT47 and ROC22, the edge and lateral separation zone grew deformed, the upper edge and lower edge were not parallel and formed a larger opening angle, and the brown area of +3 to +7 leaves was larger.

[0055] (2) In terms of main metabolic products, ROC22 had the highest sheath cellulose and lignin contents, followed by GT60, and GT47 had the lowest content. There was no significant difference in hemicellulose content among the three varieties. The peroxidase (POD) activity of ROC22 was higher than that of the other two varieties at the edge and side of the leaf sheath. GT47 had the lowest enzyme activity, and GT60 was between ROC22 and GT47. GT60 had the highest malondialdehyde (MDA) content, followed by ROC22, and GT47 had the lowest content. The endo-β-1, 4-glucanase activity of GT47 was slightly different at the edge and side, but significantly increased at the central axis. ROC22 had little difference in content at the edge, side, and central axis. GT60 had a higher edge content, lower side and central axis content. The exo-β-1, 4-glucanase / cellobiohydrolase (CBH) activity of GT47 was higher than that of ROC22 and GT60 at the edge, side, and central axis. GT60 had the lowest content at the edge, and the activity at the side and central axis increased by several times. ROC22 gradually decreased from the edge to the central axis, and the side and central axis were lower than GT47 and GT60.

[0056] Conclusion: The natural defoliation of plants is controlled by its own genes. Sugarcane defoliation is different from woody defoliation plants. The leaf sheath of woody defoliation plants does not wrap around the stem, and after the abscission layer breaks, it directly falls off under the action of external force. However, the leaf sheath of sugarcane tightly wraps around the cane, and only after completing the two processes of sheath-stem separation and abscission layer breakage can it fall off. Therefore, in addition to considering the abscission layer tissue senescence and separation in the study of sugarcane defoliation, the factor of leaf sheath wrapping around the cane should also be considered. In a sugarcane population, mature leaf blades of different genotypes have different growth states, such as leaf sheath tightly wrapping around the cane without exposing the cane, leaf sheath tightly wrapping around the cane exposing the cane, leaf sheath loosely wrapping around the cane without exposing the cane, and leaf sheath loosely wrapping around the cane exposing the cane. Some genotypes tightly wrap around the cane throughout the growth period, while some genotypes begin to separate the sheath and stem after the booting stage, causing leaf abscission. There are also significant differences in defoliation characteristics among different genotypes. Therefore, sugarcane defoliation has special characteristics and is closely related to the development of leaf sheath morphology, abscission layer tissue development, and physiological function senescence.

[0057] Based on the above research, the applicant believes that the looseness of the leaf sheath wrapping around the cane, the inclination angle of the leaf sheath, and the degree of deformation of the abscission zone have the greatest contribution rate to the defoliation of sugarcane. They are collectively used to evaluate the defoliation of sugarcane.

[0058] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer, characterized in that, Includes the following steps: (1) Leaf sheath diameter, internode diameter, leaf sheath tilt angle and malondialdehyde in abscission layer are used as evaluation indicators; (2) Observe the evaluation indicators; (3) Based on the observation results of the evaluation indicators, sugarcane was divided into three types: automatic leaf-removing varieties, difficult-to-remove-leaf varieties, and easy-to-remove-leaf varieties; among them, The automatically defoliating variety is characterized by: leaf sheath diameter < internode diameter, leaf sheath tilt angle > 0°, malondialdehyde content in the abscission layer > 17 nmol / g, and open-chain dissolution at the leaf sheath base, enabling it to detach automatically. The easily detachable leaf type variety has the following characteristics: leaf sheath diameter > internode diameter, leaf sheath tilt angle = 0°, malondialdehyde content of abscission layer is 10-17 nmol / g, leaf sheath base has open chain dissolution but does not fall off automatically, and after dissolution, the entire leaf sheath hangs on the sugarcane stalk. The difficult-to-peel leaf type variety is characterized by: leaf sheath diameter = internode diameter, leaf sheath tilt angle = 0°, malondialdehyde content in the abscission layer < 10 nmol / g, and no open-chain dissolution at the leaf sheath base.

2. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The observation period for all evaluation indicators is the mature stage.

3. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The leaf sheath diameter and internode diameter are measured for any leaf from +7 to +10.

4. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The leaf blade for which the leaf sheath tilt angle is measured is either +9 or +10.

5. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The leaves for which malondialdehyde (MDA) was measured were either +9 leaves or +10 leaves.

6. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The leaf sheath base dissolution observation leaf is +9 leaf or +10 leaf.

7. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 3, 4, 5, or 6, characterized in that, The position of the leaves is as follows: the leaf at the junction of the leaf sheath and the leaf at the sugarcane tip is +1 leaf, and towards the base of the sugarcane, each node is sequentially set to +2 leaves, +3 leaves, +4 leaves, +5 leaves, up to +10 leaves.

8. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The malondialdehyde (MDA) content in the leaf sheath base is the average value measured in the edge, side, and central axis.

9. The method for evaluating sugarcane defoliation using allometric growth of stems and sheaths and malondialdehyde content in the abscission layer according to claim 1, characterized in that, The leaf sheath base open-chain dissolution time of the easily defoliated variety is later than that of the automatically defoliated variety.