Method for enhancing stress tolerance of pakchoi to selenium-rich and high-cadmium soil

Abstract

The invention belongs to the technical field of selenium enrichment of pakchoi, and particularly relates to a method for enhancing tolerance of pakchoi to stress of selenium-rich and high-cadmium soil, which comprises the following steps: in a 4-5-leaf period of pakchoi, diluting a jasmonic acid solution by 50 times with water, and uniformly spraying the diluted solution on the front and back surfaces of pakchoi leaves until the leaf surfaces are completely wet and water drops can be seen to flow down on the leaf surfaces; the spraying is continuously performed for three times, and the interval between two adjacent times is 5 days. The jasmonic acid is selected as a growth regulating substance, the problems of pollution introduction, ecological damage and the like do not exist, the tolerance of crops to selenium-rich and high-cadmium stress can be effectively enhanced, the selenium content of edible parts of the crops on the ground is increased, the cadmium content of the edible parts is reduced, the purposes of achieving multiple effects and multiple purposes through one method are achieved, the production efficiency of the selenium-rich crops is integrally improved, and the production cost is reduced. Technical support is provided for efficient and safe utilization of selenium-rich and high-cadmium soil, and meanwhile development of agricultural measures based on crop physiological regulation and control is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of selenium-enriched pakchoi, and particularly relates to a method for enhancing the tolerance of pakchoi to stress of selenium-enriched and high-cadmium soil. Background Art

[0002] Selenium (Se) is one of the essential trace elements for humans and animals, and plays an important role in maintaining the health of the body. Studies have shown that organic selenium is superior to inorganic selenium in terms of safety, bioavailability, antioxidant effect, and improving the body's immunity and fertility. So far, no human or animal has been found to have symptoms of selenium poisoning due to excessive intake of organic selenium. However, at this stage, organic selenium is still a "scarce resource", and crops have the ability to absorb and transform inorganic selenium. Generally, organic selenium in plants accounts for more than 80% of the total selenium. At this stage, increasing the selenium content of crops is one of the most important and direct methods to provide organic selenium nutrition. On the other hand, cadmium is one of the most important heavy metals that affect the safety and growth of agricultural products. Cadmium (Cd) in the soil enters the human body through the soil-crop absorption and transport system and then through the food chain, thus threatening human health.

[0003] Selenium-rich soil (Se≥0.4mg / kg) is an important material basis and valuable resource for the development of selenium-rich agriculture. However, Se and Cd are geochemical co-existing elements, so they co-exist in the soil during migration and transformation. Selenium-rich soil has a great risk of cadmium pollution. The selenium-rich areas in Jinhua, Zhejiang, Shitai County, Chizhou, Anhui, the selenium-rich soil areas in Hainan, and the selenium-rich areas in southern Shaanxi have all been found to have cadmium content exceeding the standard to varying degrees. The 1:250,000 surface soil geochemical survey data from Enshi Prefecture, Hubei Province showed that the selenium-rich and high-cadmium soil areas (Se≥0.4mg / kg; Cd≥0.3mg / kg) accounted for 45.14% of the area of ​​Enshi Prefecture, covering an area of ​​approximately 10,878.74km 2 . The cadmium exceeding standard rate in fish ponds in high-selenium areas is as high as 100%, and the cadmium exceeding standard multiples are as high as 8 to 800 times. Guangxi's selenium-rich soil also has a high cadmium background value. The cadmium content of a typical selenium-rich and high-cadmium area is 0.30-244.1 mg / kg. Although agricultural products in selenium-rich and high-cadmium soils are rich in selenium, their cadmium content is also generally exceeded, seriously endangering the quality and safety of agricultural products. In addition, cadmium is a heavy metal element that is not essential for plant growth and development. High-cadmium soil is one of the important stress factors that endanger the healthy growth of crops; at the same time, selenium has no special metabolic channels in crops and can only rely on replacing the position of sulfur to bind to proteins. Therefore, increasing the selenium content of crops is likely to cause protein structure and function disorders and produce toxic effects. Selenium-rich and high-cadmium soils have the dual stress factor conditions of high selenium and high cadmium at the same time, which is an important factor leading to crop yield reduction. It can be seen that enhancing the tolerance of crops to the stress of selenium-rich and high-cadmium soils and reducing the cadmium content of crops in selenium-rich and high-cadmium areas are important bottlenecks that need to be overcome in order to safely produce selenium-rich crops and improve production efficiency in selenium-rich areas.

[0004] At present, in addition to the relevant mechanisms of plants themselves to cope with Cd and Se stress (antioxidant regulation, hormone regulation, etc.). The technical measures to reduce the Cd content and Cd stress hazards of crops have become relatively mature and diverse, and can be roughly divided into three aspects: chemical fortification, biological fortification, and agronomic regulation. The technology to reduce the harm of single Se stress is mainly found in agronomic regulation measures of exogenous plant hormones. Among them, applying exogenous selenium (nanoselenium, organic selenium, inorganic selenium, selenium fertilizer) through leaves or soil is still the most important technical method to increase crop selenium content, reduce cadmium content, and improve crop stress resistance under selenium-rich and high-cadmium soil conditions. However, this not only fails to give full play to the advantages of selenium-rich soil resources, but may also bring a series of new environmental problems (selenium pollution in water bodies, etc.). In order to better utilize selenium-rich soil resources and deal with the problem of soil selenium-cadmium co-existence stress, it is still necessary to develop simpler, more practical, efficient, and environmentally friendly methods to enhance the tolerance of pakchoi to selenium-rich and high-cadmium stress.

[0005] Applying exogenous selenium (nanoselenium, organic selenium, inorganic selenium, selenium fertilizer) through leaves or soil is still the most important technical method in the process of utilizing selenium-rich and high-cadmium soil, because this technology can well increase the selenium content of crops, thereby increasing the added value of crops, and at the same time it is also helpful to reduce the cadmium content of plants and alleviate the stress and toxicity of plants. However, the effect of exogenous selenium on cadmium absorption is interfered by many factors such as exogenous selenium concentration, type (form), use method / frequency, crop variety, environmental conditions, etc., and it may even promote the enrichment of cadmium in crops. On the other hand, the use of exogenous selenium may further aggravate plant toxicity, and there are problems such as seedling burning, residue (41.82%-82.64%), low utilization rate (soil-applied selenium fertilizer utilization rate 5%-30%, soil-applied sodium selenite utilization rate 0.89%-3.25%), environmental pollution and selenium resource shortage, and it is not conducive to giving full play to the advantages of selenium-rich soil resources. In addition, methods such as adding conditioners and microbial preparations to the soil to change the activity of selenium and cadmium in the soil also have good effects in some selenium-rich areas, but this method changes the chemical properties of the original soil to a certain extent, is difficult to operate, has high costs, and has the potential to damage the structure of the soil itself. In serious cases, it will also cause the loss of beneficial elements, weakening of soil fertility, and pollution of water bodies. In addition, the method of using traditional breeding methods or transgenic technology to breed selenium-rich, low-cadmium varieties with high tolerance to selenium and cadmium may be more economical in the long run, but the difficulty lies in the lack of research on the genetic mechanism of selenium / cadmium in crops and the breeding of selenium-rich, low-cadmium germplasm. The research cycle is long, the cost is high, and the stability and safety are unknown, making it difficult to promote and apply.

[0006] Overall, the current response measures for the utilization of selenium-rich and high-cadmium soils still simply focus on the technology for coping with single cadmium stress, ignoring the problems of aggravated plant toxicity and seedling burning caused by the continued application of exogenous selenium. It is necessary to develop a "one method, multiple effects, one stone, multiple benefits" technology that can simultaneously cope with selenium and cadmium stress, reduce the cadmium content of crops, and not affect the crop's absorption of soil selenium. Plant hormones have an important influence on the absorption and transport of plant ions, and are also the main growth regulators for enhancing crop resistance. Jasmonic acid is a plant hormone related to plant resistance. It is closely related to the stress response under biological / abiotic stress such as pests and diseases, salt stress, and drought stress. Jasmonic acid substances in plants can be rapidly upregulated when plants suffer external damage, thereby triggering related signal reactions to resist. In existing technical methods, under single high-selenium stress conditions, exogenous jasmonic acid can effectively improve the tolerance of plants to selenium, thereby promoting the healthy growth of crops and the accumulation of selenium. However, the situation of dual stress factors of selenium and cadmium is more complicated. Whether jasmonic acid can reduce the toxicity of dual stress of selenium and cadmium and reduce the cadmium content of crops at the same time still needs further exploration. The concentration of jasmonic acid suitable for selenium-rich and high-cadmium soil conditions also needs further testing.

[0007] So far, there is no report on the use of jasmonic acid in improving the tolerance of pakchoi to selenium-rich and high-cadmium stress.

[0008] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0009] The object of the present invention is to provide a method for enhancing the tolerance of pakchoi to the stress of selenium-rich and high-cadmium soil.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress, comprising: when the Chinese cabbage is in the 4-5 leaf stage, diluting a jasmonic acid solution 50 times with water and spraying it evenly on the front and back sides of the Chinese cabbage leaves until the leaf surface is completely wet and water droplets can be seen flowing down the leaf surface; spraying continuously for 3 times, with an interval of 5 days between two adjacent times.

[0012] More specifically, the selenium-rich and high-cadmium soil is neutral or alkaline soil.

[0013] More specifically, in the selenium-rich and high-cadmium soil, the cadmium content is 0.8 mg / kg≤<3 mg / kg, and the selenium content is ≥2.0 mg / kg.

[0014] More specifically, the concentration of the jasmonic acid solution is 1 mmol / L.

[0015] More specifically, the preparation method of the jasmonic acid solution is: dissolve 0.2103g of jasmonic acid in a beaker with 10mL of anhydrous ethanol, add 400-600mL of pure water, add 2mL of Tween-20, stir and mix, transfer to a 1L volumetric flask, make up to volume, shake well, and obtain a 1mmol / L jasmonic acid solution.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The invention is based on the problem of coexistence of selenium and cadmium commonly faced by selenium-rich soils across the country. It starts from a technology that is different from the current most important technology that relies on the application of exogenous selenium, takes crop response as the center, selects growth regulating substances that can not only help plants enhance their tolerance to selenium and cadmium stress, but also regulate the absorption and distribution of selenium and cadmium, namely jasmonic acid as the main raw material, does not have the problems of introducing pollution, destroying the ecology, and determines the optimal use concentration through experiments, can effectively enhance the tolerance of crops to selenium-rich and high-cadmium stress, and increase the selenium content in the aboveground edible part of the crops, and reduce the cadmium content in the edible part, so as to achieve the purpose of "one method with multiple effects, and achieving multiple goals with one stone", improve the production efficiency of selenium-rich crops as a whole, provide technical support for the efficient and safe utilization of selenium-rich and high-cadmium soils, and at the same time be conducive to promoting the development of agronomic measures based on crop physiological regulation. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is described clearly and completely below.

[0019] Example 1

[0020] A method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress, comprising: when the Chinese cabbage is in the 4-5 leaf stage, diluting a jasmonic acid solution 50 times with water and spraying it evenly on the front and back sides of the Chinese cabbage leaves until the leaf surface is completely wet and water droplets can be seen flowing down the leaf surface; spraying continuously for 3 times, with an interval of 5 days between two adjacent times.

[0021] The selenium-rich and high-cadmium soil is neutral or alkaline soil; in the selenium-rich and high-cadmium soil, the cadmium content is 0.8 mg / kg≤<3 mg / kg, and the selenium content is ≥2.0 mg / kg. In addition, the concentration of the jasmonic acid solution is 1 mmol / L.

[0022] In this embodiment, the preparation method of the jasmonic acid solution is as follows: 0.2103g of jasmonic acid is dissolved in 10mL of anhydrous ethanol in a beaker, 400-600mL of pure water is added, and 2mL of Tween-20 is added at the same time, and the mixture is stirred and mixed, and the mixture is transferred to a 1L volumetric flask, fixed to volume, and shaken to obtain a 1mmol / L jasmonic acid solution.

[0023] Example 2

[0024] Neutral soil (pH = 7.0) was selected. Before planting Chinese cabbage, sodium selenate and cadmium chloride were dissolved in water and sprayed into the soil. After mixing and aging for 6 months, the soil selenium content was measured to be 2.18 mg / kg and the soil cadmium content was 1.58 mg / kg, thus obtaining selenium-rich and high-cadmium soil.

[0025] On October 25, 2023, Chinese cabbage was sown in the prepared selenium-rich and high-cadmium soil. When the Chinese cabbage was 4-5 leaves (November 24), the method of Example 1 was followed. Other daily management was carried out in a conventional manner, and a control of spraying an equal amount of clean water was set. After implementation, samples were collected on December 14, 2023 and relevant indicators were tested. The results are shown in Tables 1 to 4.

[0026] Table 1 Effect of the planting method of the present invention on the malondialdehyde content and antioxidant enzyme activity of Chinese cabbage in selenium-rich and high-cadmium soil

[0027]

[0028] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0029] Malondialdehyde is an indicator of the degree of cell membrane lipid peroxidation, and its content will increase significantly when plants are subjected to adverse stress. As shown in Table 1, after being treated according to the method of the present invention, the malondialdehyde content of the leaves of Chinese cabbage is significantly reduced, and the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the leaves are significantly increased. It is shown that the method of the present invention reduces the level of cell membrane lipid peroxidation caused by selenium-rich and high-cadmium soil stress by improving the antioxidant enzyme activity of Chinese cabbage, thereby alleviating the cell toxicity caused by selenium-rich and high-cadmium soil stress.

[0030] Table 2 Effect of the planting method of the present invention on non-enzyme resistance substances of Chinese cabbage in selenium-rich and high-cadmium soil

[0031]

[0032] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0033] As can be seen from Table 2, in addition to enhancing enzyme antioxidant substances, the method of the present invention significantly enhances non-enzyme resistance substances such as metallothionein and root phytochelatin in Pakchoi roots. Both metallothionein and phytochelatin have the function of removing free radicals and reactive oxygen caused by abiotic stress factors, and play an important role in reducing the toxicity of free heavy metal / metalloid ions to cells and improving plant resistance.

[0034] Table 3 Effect of the method of the present invention on photosynthetic pigments and fresh weight of Chinese cabbage in selenium-rich and cadmium-rich soil

[0035]

[0036] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0037] The enhancement of plant tolerance to selenium-rich and high-cadmium soil stress is also reflected in the improvement of photosynthetic pigments. As shown in Table 3, compared with the control, after treatment according to the method of the present invention, the content of green pigment a, chlorophyll b, total chlorophyll content and carotenoid content of Chinese cabbage were significantly increased. The increase of chlorophyll and carotenoid is very important for enhancing plant photosynthesis and increasing yield. It can be seen that the method of the present invention can significantly improve the photosynthetic potential of Chinese cabbage under selenium-rich and high-cadmium stress. Based on the enhancement of physiological tolerance, the implementation of this method also significantly increased the fresh weight of the aboveground part of Chinese cabbage, and the promotion effect on the growth of Chinese cabbage under selenium-rich and high-cadmium stress was obvious.

[0038] Table 4 Effect of the method of the present invention on the selenium and cadmium content of Chinese cabbage in selenium-rich and high-cadmium soil

[0039]

[0040] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0041] As can be seen from Table 4, the method of the present invention significantly increases the content of selenium, a beneficial element, in the aerial part of Chinese cabbage, while reducing the content of cadmium, a harmful element, in the aerial part, which can both alleviate the problem of excessive cadmium in crops and help improve the production efficiency of selenium in crops.

[0042] As a whole, it can be seen that the method of the present invention reduces the cellular peroxidation toxicity caused by selenium-rich and high-cadmium soil stress by increasing the activity of antioxidant enzymes and the content of non-enzyme resistance substances, promotes the synthesis of photosynthetic pigments and the increase of the fresh weight of the aboveground part, and at the same time increases the content of the beneficial element selenium in the edible part and reduces the content of the harmful element cadmium, achieving "one method with multiple effects and achieving multiple goals with one stone", and can effectively alleviate the problems of crop yield reduction and cadmium excess in the utilization process of selenium-rich and high-cadmium soil, providing technical support for the safe utilization of selenium-rich and high-cadmium soil.

[0043] Example 3

[0044] Alkaline soil (pH = 7.6) was selected. Before planting Chinese cabbage, more sodium selenate and cadmium chloride were dissolved in water and sprayed into the soil. After mixing and aging for 6 months, the soil selenium content was measured to be 2.85 mg / kg and the soil cadmium content was 1.92 mg / kg. Both the soil selenium content and the soil cadmium content were higher than those in Example 2.

[0045] On March 7, 2024, Chinese cabbage was sown in the prepared selenium-rich and high-cadmium soil. When the Chinese cabbage was 4-5 leaves (April 5), the method of Example 1 was followed. Other daily management was carried out in a conventional manner, and a control of spraying an equal amount of clean water was set. After implementation, samples were collected and tested on April 24, 2024, and the results are shown in Tables 5 to 8.

[0046] Table 5 Effect of the planting method of the present invention on the malondialdehyde content and antioxidant enzyme activity of Chinese cabbage in selenium-rich and high-cadmium soil

[0047]

[0048] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0049] As shown in Table 5, the method of the present invention significantly reduces the malondialdehyde content in leaves, indicating that the present technology reduces the level of cell membrane lipid peroxidation caused by selenium-rich high-cadmium soil stress (Table 5). The main reason for this is that the implementation of the present technology significantly increases the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in leaves, which plays an important role in scavenging oxygen free radicals and reducing cell peroxidation levels.

[0050] Table 6 Effect of the planting method of the present invention on non-enzyme resistance substances of Chinese cabbage in selenium-rich and high-cadmium soil

[0051]

[0052] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0053] As shown in Table 6, the method of the present invention also significantly improves non-enzyme resistant substances, namely leaf non-protein thiol groups, root metallothionein, root phytochelatin, etc. Non-protein thiol groups have similar functions to metallothionein and phytochelatin, both of which have abundant thiol groups and are easy to bind to metal ions, reducing free metal ions in cells, thereby achieving the purpose of enhancing tolerance.

[0054] Table 7 Effect of the method of the present invention on photosynthetic pigments and fresh weight of Chinese cabbage in selenium-rich and cadmium-rich soil

[0055]

[0056] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0057] As shown in Table 7, compared with the control, after treatment according to the method of the present invention, the content of green pigment a and total chlorophyll in Chinese cabbage also increased significantly (Table 7), which is also conducive to improving the photosynthesis potential of Chinese cabbage under selenium-rich and high-cadmium stress. Based on the enhancement of physiological tolerance, the implementation of this method also significantly increased the aboveground fresh weight and root fresh weight of Chinese cabbage (Table 7). It can be seen that the technical method has a significant promoting effect on the growth physiology of Chinese cabbage under selenium-rich and high-cadmium soil stress.

[0058] Table 8 Effect of the method of the present invention on the selenium and cadmium content of Chinese cabbage in selenium-rich and high-cadmium soil

[0059]

[0060] Note: The values ​​in the table are mean ± standard deviation (n = 3). Different lowercase letters indicate significant differences between the technology group and the control group (P < 0.05).

[0061] As shown in Table 8, the method of the present invention also has a certain promoting effect on the selenium content of the aboveground edible part. At the same time, the cadmium content of the aboveground part of Chinese cabbage is significantly reduced (Table 8), which is beneficial to increase the selenium content of the crop and reduce the content of the harmful cadmium element.

[0062] In summary, the method of the present invention reduces the cellular peroxidation toxicity caused by selenium-rich and high-cadmium soil stress by increasing the activity of antioxidant enzymes and the content of non-enzyme resistance substances, promotes the synthesis of photosynthetic pigments and the increase of the fresh weight of the aboveground part, and at the same time increases the content of the beneficial element selenium in the edible part and reduces the content of the harmful element cadmium, thereby achieving "one method with multiple effects and achieving multiple goals with one stone", and can effectively alleviate the problems of crop yield reduction and excessive cadmium in the process of utilizing selenium-rich and high-cadmium soil, thus providing technical support for the safe utilization of selenium-rich and high-cadmium soil.

[0063] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress, characterized in that: include: When the cabbage is in the 4-5 leaf stage, dilute the jasmonic acid solution 50 times with water and spray it evenly on the front and back of the cabbage leaves until the leaf surface is completely wet and water droplets can be seen flowing down the leaf surface; spray continuously for 3 times, with an interval of 5 days between each 2 times.

2. The method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress according to claim 1, characterized in that: The selenium-rich and high-cadmium soil is neutral or alkaline soil.

3. The method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress according to claim 1, characterized in that: In the selenium-rich and high-cadmium soil, the cadmium content is 0.8mg / kg≤<3mg / kg, and the selenium content is ≥2.0mg / kg.

4. The method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress according to claim 1, characterized in that: The concentration of the jasmonic acid solution is 1 mmol / L.

5. The method for enhancing the tolerance of Chinese cabbage to selenium-rich and high-cadmium soil stress according to claim 1, characterized in that: The preparation method of the jasmonic acid solution is as follows: 0.2103g of jasmonic acid is dissolved in 10mL of anhydrous ethanol in a beaker, 400-600mL of pure water is added, and 2mL of Tween-20 is added at the same time, and the mixture is stirred and mixed, and the mixture is transferred to a 1L volumetric flask, fixed to volume, and shaken to obtain a 1mmol / L jasmonic acid solution.

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