Method for evaluating waterlogging tolerance of eggplant rootstock

Abstract

The present application relates to the field of plant cultivation and stress resistance identification technology, in particular to a method for evaluating the waterlogging tolerance of eggplant rootstock, which comprises the following steps: sowing and seedling raising, removing the top of the seedlings at the 4-5 leaf stage, retaining the lower rootstock and 2-3 true leaves; waterlogging treatment, the water surface being higher than the top of the seedlings during the waterlogging treatment; taking out the seedlings after the waterlogging treatment, and recovering growth; and evaluating the waterlogging tolerance of the eggplant rootstock according to the recovery growth. The method can solve the problems of serious dependence on experience, large deviation, complicated operation and high cost in the evaluation of the waterlogging tolerance of eggplant rootstock.

Description

Technical Field

[0001] This invention relates to the field of plant cultivation and stress resistance identification technology, specifically a method for evaluating the waterlogging tolerance of eggplant rootstock. Background Technology

[0002] Eggplant (Solanum melongena L.) is a plant belonging to the genus Solanum in the family Solanaceae. It is widely cultivated throughout my country. Due to the increasing severity of soil-borne diseases and continuous cropping obstacles, the area of ​​grafted eggplant cultivation has exceeded that of traditional seedling cultivation, leading to the development of multi-resistant rootstock eggplant varieties. In the Yangtze River basin and areas south of it in my country, seasonal rainfall makes eggplant highly susceptible to waterlogging stress, severely impacting its growth, yield, and quality.

[0003] Chinese Patent Publication No. CN107155666A discloses a method for rapid identification of waterlogging tolerance in eggplant, comprising the following steps: Step 1: Waterlogging treatment is applied to four-leaf, one-heart eggplant seedlings, with the water level 2 cm above the soil surface, for 14 days; Step 2: After 14 days of waterlogging, waterlogging recovery treatment is performed. After 7 days of recovery, the phenotypic characteristics of the eggplant seedlings are observed, using two evaluation indicators: leaf color and abscission rate, and stem morphology; Step 3: The two evaluation indicators of leaf color and abscission rate and stem morphology are used for further evaluation. The process involves several steps: First, quantitative grading is performed, and a grading scoring standard is established. Second, the grading score of each eggplant seedling is determined using the standard, and the average score for each seedling is calculated. Third, the waterlogging tolerance membership function is calculated using the average score. The average membership function value is obtained by summing the two membership function values ​​for each seedling. This average membership function value is then used to compare the waterlogging tolerance of different eggplant seedlings; a higher overall membership function value indicates stronger waterlogging tolerance. However, this method relies heavily on subjective judgment by operators based on the color and morphology of roots, stems, and leaves. The results from different operators can vary significantly, making it ineffective in assessing waterlogging tolerance. Current technologies evaluate waterlogging tolerance more effectively by examining changes in the ultrastructure of leaf cells under waterlogging stress. However, this method is highly specialized, complex, and costly, making it unsuitable for evaluation in complex and variable field environments. Summary of the Invention

[0004] The purpose of this invention is to provide a method for evaluating the flood tolerance of eggplant rootstock, which can solve the problems of heavy reliance on experience, large deviations, complex operation, and high cost in evaluating the flood tolerance of eggplant rootstock.

[0005] This application provides the following technical solution:

[0006] A method for evaluating the waterlogging tolerance of eggplant rootstock includes sowing and raising seedlings. When the seedlings have 4-5 leaves, the top is cut off, leaving the lower rhizome and 2-3 true leaves. The seedlings are then subjected to waterlogging treatment, with the water level above the top of the seedlings. After the waterlogging treatment is completed, the seedlings are removed and allowed to recover. The waterlogging tolerance of the eggplant rootstock is evaluated based on the recovery of growth.

[0007] Beneficial Effects: This technical solution, based on the rootstock characteristics of eggplant, is performed at the 4-5 leaf stage of seedlings. At this stage, the root system and above-ground parts of the seedlings grow in coordination and sensitively exhibit adaptability to waterlogging, highlighting the rootstock's inherent waterlogging tolerance potential. Removing the apical dominance avoids interference from differences in the growth height of the main stem at the apex of different germplasms in the evaluation of waterlogging tolerance. Compared to existing techniques that retain the apex when evaluating seedling waterlogging tolerance, where some seedlings, after stress treatment, show signs of root and stem rot or other damage while the apex remains upright and the leaves are relatively intact, thus affecting the overall waterlogging tolerance evaluation, this method uses the underground part of the eggplant rootstock as the grafted seedling. After grafting, only the roots are retained, and the apex is removed, simulating the actual application of eggplant rootstock in production, making the evaluation results more accurate. During the flooding treatment, the water level is higher than the top of the seedlings, simulating severe waterlogging and deep flooding conditions that may occur in the field. This allows for a comprehensive evaluation of the tolerance limits of eggplant rootstocks under extremely hypoxic and prolonged deep flooding conditions, increasing the damage to the plants and visually distinguishing the flood tolerance of different eggplant rootstocks. Even if severely damaged in floods, if the rootstock can quickly recover, regrow branches and leaves, and restore root function, it can ensure the growth and yield of subsequent eggplant scions. From a long-term production benefit perspective, selecting rootstocks with strong recovery capabilities can reduce the risk of yield reduction and crop failure caused by flooding, stabilizing the economic benefits of the eggplant planting industry.

[0008] Furthermore, the flood treatment temperature is 20-30℃, and the flood treatment time is 7-10 days.

[0009] Beneficial effects: Flooding treatment at 20-30℃ for 7-10 days achieves a level of damage to eggplant germplasm that meets evaluation criteria. If the flooding treatment time is less than 7 days, the damage to eggplant germplasm is insufficient and cannot accurately reflect true flood tolerance. If the flooding treatment time is greater than 10 days, excessive damage to eggplant germplasm occurs, leading to blurred individual differences and large errors in the evaluation results.

[0010] Furthermore, in the flooding treatment, a flood-sensitive control group is set up. The leaf drop rate of the flood-sensitive control group is ≥90%, and the flooding treatment is completed.

[0011] Beneficial effects: By setting up a waterlogging-sensitive control group and using a leaf drop rate of ≥90% in the control group as the end of the treatment, the stress intensity of waterlogging was objectively quantified. Relying on the clear response (leaf drop) of the waterlogging-sensitive control group rather than a fixed time setting reduced human judgment errors and improved the objectivity of the experimental results.

[0012] Furthermore, for the sowing and seedling raising, select plump seeds, soak them in 0.5g / L gibberellic acid at a temperature of 10-35℃ for 16-24 hours, dry them, sow them in seedling trays, and manage them normally in the field until the seedlings have 4-5 leaves.

[0013] Beneficial effects: Gibberellic acid breaks eggplant seed dormancy, ensuring rapid and uniform emergence after sowing. Normal field management refers to suitable temperature, light, and water and fertilizer management measures for eggplant seed germination and emergence. Seedlings at the 4-5 leaf stage have relatively robust rootstocks, possessing a certain capacity for absorbing and transporting water and nutrients, and are more sensitive to environmental stress, thus more accurately reflecting differences in waterlogging tolerance of eggplant rootstocks. Seedlings that are too small have weak growth vigor and limited growth and adaptability, failing to accurately reflect the waterlogging tolerance characteristics of eggplant rootstocks. Seedlings that are too large have high field management and time costs, increasing the cost of waterlogging tolerance evaluation.

[0014] Furthermore, after sowing and seedling cultivation, the seedlings are screened, and those that are normal, healthy, and have similar growth status are retained.

[0015] Beneficial effects: It ensures that the seedlings undergoing flood tolerance evaluation are in a basically consistent state of growth and health, thus ensuring the accuracy of the flood tolerance evaluation.

[0016] Furthermore, in the aforementioned flooding treatment, the water level is 10-15cm higher than the top of the seedlings.

[0017] Beneficial effects: Maintaining a certain water depth can realistically simulate such severe flooding scenarios, ensuring that the environment around the seedlings is in a relatively stable hypoxic state, and guaranteeing the accuracy of flood tolerance evaluation.

[0018] Furthermore, the recovery and growth period is 15-20 days.

[0019] Beneficial effects: 15-20 days is a relatively ample time, allowing eggplant rootstock seedlings that have experienced flooding stress to fully demonstrate their ability to recover and grow.

[0020] Furthermore, the method for evaluating the waterlogging tolerance of eggplant rootstock based on its recovery growth is as follows:

[0021] Calculate the survival rate of plants after waterlogging: Survival rate of plants after waterlogging = Number of plants that have recovered growth / Total number of plants treated with waterlogging.

[0022] Waterlogging tolerance was evaluated based on the survival rate of plants after waterlogging: Strong: P ≥ 65%; Medium: 35% ≤ P < 65%; Weak: P < 35%.

[0023] Beneficial effects: By simulating flood stress, the judgment of flood resistance is based solely on the survival rate after recovery and growth, which greatly reduces the difficulty of judging different levels and has the advantages of simple operation, good repeatability and high reliability. Detailed Implementation

[0024] The following detailed description illustrates the specific implementation method:

[0025] Example 1

[0026] A method for evaluating the waterlogging tolerance of eggplant for rootstocks includes the following steps:

[0027] (1) Sowing and seedling raising: Select plump seeds, soak them in 0.5g / L gibberellic acid at a temperature of 10-35℃ for 16-24 hours, dry them, sow them in seedling trays, and manage them normally in the field until the seedlings have 4-5 leaves.

[0028] (2) Head removal treatment: Select seedlings and remove those with signs of death, leaf drop, yellowing and wilting, and retain normal and healthy seedlings; and make a comprehensive judgment based on the number of leaves, stem thickness and plant height of the seedlings, select seedlings with basically the same growth status, cut off the top with a blade, and retain the lower rhizome, 2-3 true leaves and 2 cotyledons.

[0029] (3) Flooding Treatment: Spread a layer of gravelly soil on the surface of the seedling substrate in the seedling trays. The gravelly soil is used to ensure the stability of the seedlings after watering. Place the seedling trays with the tops removed in the flooding pond or basket, and add water until the water level is 10-15 cm above the top of the seedlings. Keep the water level stable, and the water level should always be above the top of the seedlings during the flooding treatment. Flooding treatment should be carried out for 7-10 days at an air temperature of 20-30℃. A flood-sensitive control group can be set up simultaneously. When the leaf drop rate of the flood-sensitive control group is ≥90% after 7-10 days of flooding treatment, the time when the leaf drop rate of the flood-sensitive control group is ≥90% is taken as the end time of flooding treatment. When the flooding treatment time is ≤6 days and the leaf drop rate of the flood-sensitive control group is ≥90%, the flooding treatment is ended when the leaf drop rate of the flood-sensitive control group is ≥90%. Check whether any abnormalities occur during the flooding treatment, such as large temperature fluctuations. If so, repeat the experiment; if not, proceed to the next step and replace the flood-sensitive control group to repeat the experiment for verification. If the leaf drop rate of the flood-sensitive control group is not ≥90% after ≥11 days of flooding treatment, check whether any abnormalities occurred during the flooding treatment process. If so, repeat the experiment. If not, continue the flooding treatment until the leaf drop rate of the flood-sensitive control group is ≥90%. Then, end the flooding treatment and proceed to the next step, and replace the flood-sensitive control group to repeat the experiment for verification.

[0030] The flood-sensitive control group consisted of eggplant varieties with low flood tolerance, such as "March Eggplant," which is recognized by experts as having extremely low flood tolerance. The sowing, seedling raising, topping, and flooding treatment processes for the flood-sensitive control group were the same as those for the group to be evaluated. Leaf drop rates in the flood-sensitive control group could be obtained through direct observation, including leaves that naturally fell off due to decay after prolonged deep flooding, and leaves that easily fell off during manual removal of residual leaves and debris.

[0031] (4) Resumption of growth management: After the flooding is resolved, remove the seedling trays from the flooded pond or basket and resume normal field management for 15-20 days.

[0032] (5) Recovery status survey: When new buds or leaves grow on the main stem of the seedling, it is determined that the seedling has resumed growth.

[0033] The survival rate (P) of plants after waterlogging was calculated as: number of plants that recovered growth / number of plants treated with waterlogging tolerance. Waterlogging tolerance was evaluated based on the survival rate: Strong: P ≥ 65%; Moderate: 35% ≤ P < 65%; Weak: P < 35%.

[0034] Experiment 1

[0035] Experimental methods: Using "March Eggplant" as a flood-sensitive control group for eggplant rootstock germplasm, the flood tolerance of 6 eggplant rootstock germplasm samples was evaluated.

[0036] Using the sowing and seedling raising method described in Example 1, six eggplant rootstock germplasm samples and a flood-sensitive control group were sown and raised. Each eggplant germplasm sample was cultivated into 150 seedlings. When the seedlings reached the 4-5 leaf stage, 90 seedlings with similar growth were selected and divided into three groups of 30 seedlings each. The first group was managed according to the method described in Example 1. During flooding treatment, the *March eggplant* variety served as the flood-sensitive control group. After 8 days of flooding treatment, the leaf drop rate in the flood-sensitive control group reached 100%. The second group was managed according to the method described in Example 1, except that no topping treatment was performed. During flooding treatment, the *March eggplant* variety served as the flood-sensitive control group. After 13 days of flooding treatment, the leaf drop rate in the flood-sensitive control group reached 100%. The third group was managed according to the method described in Example 1, except that during flooding treatment, the water level was 2-3 cm above the seedling tip. The *March eggplant* variety served as the flood-sensitive control group. After 20 days of flooding treatment, the leaf drop rate in the flood-sensitive control group reached 100%. The results of the flood tolerance evaluation of the six eggplant rootstock germplasms and the flood-sensitive control group are shown in Table 1.

[0037] Experiment 2

[0038] The waterlogging tolerance of seven eggplant germplasms, including the 'March Eggplant' variety, was evaluated using existing methods. Experimental methods: During seedling cultivation, normal watering was maintained to keep the soil moist; at the 4-leaf stage, a water layer of 1–2 cm was maintained on the soil surface, and plant growth was observed. When 40% of the plants in all tested germplasms wilted and recovered slowly, all seedlings were subjected to normal field management. Five days later, the recovery status of all tested germplasms was investigated, and the recovery level was divided into five grades based on the recovery and mortality status of the plants.

[0039] Grade 0: The leaves have mostly recovered, or only the leaf tips are slightly withered and yellow;

[0040] Grade 1: No dead leaves, no more than 3 yellow leaves;

[0041] Level 2: Basic recovery of growth, with no more than 2 dead leaves;

[0042] Level 3: 3-4 completely dead leaves, with new leaves growing.

[0043] Level 4: Plants are basically dead.

[0044] The recovery index is calculated based on the recovery level, using the following formula:

[0045]

[0046] Where: RI is the recovery index, x i n represents the number of plants affected by waterlogging at each level. i The values ​​represent the flood damage levels, and N represents the total number of plants surveyed.

[0047] Based on the waterlogging index, seedling waterlogging tolerance was divided into three levels: strong (recovery index < 35%), medium (35% ≤ recovery index < 65%), and weak (recovery index ≥ 65%). The evaluation results of waterlogging tolerance of seven eggplant germplasms are shown in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] Table 1 shows that for the seedlings in the third group of each germplasm in Experiment 1, the water level during the flooding treatment was 2-3 cm higher than the top of the seedlings. During the flooding treatment, some seedlings continued to grow, and after the flooding treatment, some seedlings had grown above the water surface. The flooding tolerance evaluation results of the third group were closest to those of Experiment 2. This indicates that the evaluation method of the third group did not sufficiently subject the seedlings to flooding damage and could not accurately reflect the true flood tolerance of the germplasm. For the seedlings in the second group of each germplasm in Experiment 1, the water level was increased compared to the third group. During the flooding, the seedlings remained below the water surface, increasing the damage to the seedlings. After recovery and management, the survival rate was low, and it still could not accurately reflect the true flood tolerance of the germplasm. Compared to the first group of seedlings, because the top was not removed, the leaf drop of the flood-sensitive control group took longer, increasing the damage to the seedlings. After recovery and management, the survival rate was low, and it still could not accurately reflect the true flood tolerance of the germplasm. Compared to the second group, the seedlings in the first group of each germplasm in Experiment 1 showed faster leaf drop and shorter flooding treatment time in the flood-sensitive control group. After recovery and management, the survival rate was improved, highlighting the differences between different germplasms. This indicates that removing the top stem can eliminate the interference of differences in the growth of the main stem at the top of the seedling on the flood tolerance of eggplant germplasms, and can more accurately evaluate the true flood tolerance of eggplant rootstocks.

[0052] Compared to existing technologies, this invention causes greater damage to eggplant rootstocks under simulated flood stress, making it easier to differentiate the flood resistance of different materials. Furthermore, the assessment of flood resistance is based on the survival rate after recovery management, significantly reducing the difficulty of determining different levels. This method for evaluating the flood resistance of eggplant rootstocks offers advantages such as ease of operation, good repeatability, and high reliability.

[0053] The above are merely embodiments of the present invention, and the invention is not limited to the fields covered by these embodiments. Commonly known structures and characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for evaluating the waterlogging tolerance of eggplant rootstock, characterized in that, The process includes sowing and seedling raising until the seedlings have 4-5 leaves. The top of the seedling is then removed, leaving the lower rhizome and 2-3 true leaves. The seedlings are then subjected to flooding treatment, with the water level 10-15 cm above the top of the seedlings. A flood-sensitive control group is established, with a leaf drop rate ≥90% before the flooding treatment is completed. After the flooding treatment, the seedlings are removed and allowed to recover. The recovery period is 15-20 days. The flood tolerance of the eggplant rootstock is evaluated based on the recovery progress, using the following method: Calculate the survival rate of plants after waterlogging: Survival rate of plants after waterlogging = Number of plants that have recovered / Total number of plants treated for waterlogging. Waterlogging tolerance was evaluated based on the survival rate of plants after waterlogging: Strong: P≥65%; In China: 35% ≤ P < 65%; Weak: P < 35%.

2. The method for evaluating the waterlogging tolerance of eggplant rootstock according to claim 1, characterized in that: The flood treatment temperature is 20-30℃.

3. The method for evaluating the waterlogging tolerance of eggplant rootstock according to claim 1, characterized in that: For sowing and seedling raising, select plump seeds, soak them in 0.5g / L gibberellic acid at a temperature of 10-35℃ for 16-24 hours, dry them, sow them in seedling trays, and manage them normally in the field until the seedlings have 4-5 leaves.

4. The method for evaluating the waterlogging tolerance of eggplant rootstock according to claim 1, characterized in that: After sowing and seedling raising, the seedlings are screened, and those that are normal, healthy and have similar growth status are retained.

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