A method for screening a salt-tolerant and stress-resistant wheat variety

Abstract

The application belongs to the technical field of salt-tolerant and stress-resistant wheat screening, and particularly relates to a screening method for salt-tolerant and stress-resistant wheat varieties, which comprises the following steps: S1: a plurality of layers of transparent culture mediums are arranged in a vertical direction from bottom to top in a transparent device according to the order of decreasing salinity, and a plurality of gas permeation channels are arranged in each layer of the transparent culture mediums; S2: wheat seeds of a to-be-tested variety are sowed in the uppermost layer of the transparent culture mediums, and culture is performed; S3: salt-tolerant data of the maximum penetration depth and growth morphology of the wheat root system are observed and recorded through the transparent device; and S4: as the wheat grows, the wheat roots penetrate through the culture mediums with different salinities layer by layer downwards; the salinity of the transparent culture medium layer in which the root system stops downward penetration or obvious salt damage symptoms appear is determined as the salt-tolerance threshold of the wheat variety, and the salt-tolerant wheat variety is screened out. The application is a wheat salt-tolerant and stress-resistant variety screening method which can intuitively observe the growth dynamics of the wheat root system, simultaneously simulates the vertical stratified distribution of salt in the field, and ensures sufficient oxygen supply for the root system.

Description

Technical Field

[0001] This invention belongs to the field of salt-tolerant and stress-resistant wheat screening technology, specifically relating to a screening method for salt-alkali tolerant and stress-resistant wheat varieties. Background Technology

[0002] There are many varieties of wheat, and varieties that can tolerate different salinity should be planted to suit different soils. However, there are significant differences in the salt tolerance and stress resistance of different wheat varieties. Therefore, further research is needed to explore the salt tolerance of different wheat varieties.

[0003] Existing methods for screening wheat salt tolerance mainly include hydroponics and soil culture. While roots are visible in hydroponics, the uniform salinity of the nutrient solution fails to simulate the stratified distribution of salt in field soil, making it difficult to test differences in root growth under different salinity gradients. Soil culture more closely resembles field conditions, but the roots are obscured by the soil, making it impossible to directly observe morphological changes and penetration depth during the experiment. Measurements can only be taken after the experiment, failing to obtain dynamic information on root growth.

[0004] In addition, when using solid culture media for stratified salinity tests, the poor permeability of the solid substrate can easily lead to abnormal root growth due to insufficient oxygen supply, resulting in distorted salt tolerance evaluation results. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for screening salt-alkali tolerant and stress-resistant wheat varieties. This method allows for both direct observation of wheat root growth dynamics and simulation of vertical stratification of salt distribution in the field, while ensuring sufficient oxygen supply to the roots.

[0006] The specific technical solution adopted in this invention is as follows: A method for screening salt-tolerant wheat varieties includes the following steps: S1: In a transparent device, multiple layers of transparent culture medium are arranged vertically from bottom to top according to the salinity from high to low, and each layer of transparent culture medium is provided with multiple through-breathing channels; S2: Sow wheat seeds of the test variety in the top transparent culture medium and culture them. S3: Salt tolerance data of wheat root system's maximum penetration depth and growth morphology are observed and recorded through a transparent device; S4: As wheat grows, its roots penetrate downwards through different layers of culture medium with varying salinity. The salinity of the transparent culture medium layer where the roots stop growing or show obvious salt damage symptoms is located is determined as the salt tolerance threshold of the wheat variety, and salt-tolerant wheat varieties are screened out.

[0007] The total salt content in the transparent culture medium, from bottom to top, by mass percentage, is 1%, 0.8%, 0.6%, 0.4%, 0.2%, and 0.1%.

[0008] The total salt content includes sodium chloride: magnesium chloride: sodium sulfate = 8:1:1 by weight, or sodium chloride: sodium sulfate: sodium bicarbonate = 5:4:1, and one of the two ratios is selected.

[0009] The ventilation channel is equipped with a ventilation pipe.

[0010] A gasket is also provided between the adjacent transparent culture medium layers. The gasket is located at the air venting channel, and the air venting tube passes through the transparent culture medium layer and the gasket.

[0011] The gasket has a ring structure, with the inner ring of the gasket wrapping around the vent tube and the outer ring of the gasket covering the gap between the vent channel and the vent tube; the vent tube has multiple vent holes on its wall and a non-woven fabric on its outer wall.

[0012] The transparent device also includes a lighting assembly, which includes a lamp and an L-shaped lamp post. One end of the lamp post is connected to the lamp, and the other end is connected to the top of the side wall of the transparent device, so that the lamp is directly above the transparent device.

[0013] The transparent device also includes a light-blocking cloth, which covers the transparent device and is fixed at the connection between the lamp post and the transparent device. The light-blocking cloth can be lifted or restored to observe the growth status of wheat roots.

[0014] The beneficial effects of this invention are: This invention simulates the stratified distribution of soil salinity with depth in the field by setting up a multi-layered transparent culture medium with decreasing salinity from bottom to top within a transparent device. This overcomes the shortcomings of traditional hydroponics, which results in uniform salinity and fails to reflect differences in root growth under different salinity gradients, making the screening results closer to actual field conditions. Simultaneously, the transparent culture medium keeps wheat roots visible throughout the entire cultivation process, allowing for real-time and dynamic observation and recording of maximum root penetration depth, growth morphology, and salt damage symptoms. This overcomes the limitations of soil-based cultivation, where roots are obscured by soil and measurements can only be taken after the experiment, significantly improving the efficiency and accuracy of obtaining root growth information.

[0015] This invention incorporates permeable air channels in each layer of transparent culture medium, with air vents installed within these channels. The outer walls of the air vents are wrapped with non-woven fabric. This design ensures that air can penetrate the culture medium to supply oxygen to the roots, avoiding the root suffocation caused by insufficient oxygen in traditional culture. It also prevents root tips from penetrating the air vents, effectively solving the problems of poor air permeability in solid culture media and abnormal root growth due to hypoxia, thus ensuring the reliability of salt tolerance evaluation results.

[0016] This invention improves the stability and repeatability of the device during long-term culture by setting an annular gasket between adjacent transparent culture media layers to seal the gap between the air vent and the air vent tube, preventing the culture medium from entering the air vent tube and causing blockage, while ensuring the structural stability of the air vent tube when passing through multiple layers of culture media. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a cross-sectional view of the transparent device. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: Example 1 S1: Prepare a cylindrical transparent device and a transparent culture medium. After heating and dissolving the agar, add nutrient solution and a predetermined proportion of salt, mix thoroughly, cool and solidify, and cut into 5cm thick cylindrical agar blocks. These cylindrical agar blocks are adapted to the transparent device. Multiple ventilation channels are carved axially at the same location on each cylindrical agar block. Then, a needle is inserted laterally into the agar block, ensuring that the holes created by the needle communicate with the ventilation channels.

[0019] Six layers of cylindrical agar blocks were vertically filled from bottom to top inside a transparent device, with the air channels of each layer interconnected. The total salt content of each layer of cylindrical agar blocks, by mass percentage, was 1%, 0.8%, 0.6%, 0.4%, 0.2%, and 0.1%, respectively. The salt content simulated the salt content of coastal saline-alkali land in the following proportions by weight: NaCl:MgCl2:Na2SO4 = 8:1:1.

[0020] A ring-shaped gasket is placed at the air passage between two adjacent agar blocks. Then, an air passage tube is inserted through the air passage and through the gasket. The inner ring of the gasket wraps around the air passage tube, and the outer ring of the gasket covers the gap between the air passage and the air passage tube. The outer ring of the gasket is compressed by the weight of the upper and lower agar blocks to form an airtight structure, which prevents the roots from deviating from the position of the gasket due to the tendency of air permeability between the agar blocks, thus minimizing the error.

[0021] The ventilation tube has multiple ventilation holes on its wall, with a diameter of 0.5–2 mm, evenly distributed along the axial and circumferential directions. The outer wall of the ventilation tube is wrapped with non-woven fabric. In use, air enters from the top or bottom of the ventilation tube, escapes through the ventilation holes, passes through the non-woven fabric, and permeates into the transparent culture medium, supplying oxygen to the wheat roots. Because the fiber gaps in the non-woven fabric are much smaller than the diameter of the wheat root tip, the wheat root tip cannot pass through the non-woven fabric into the ventilation tube, thus preventing root blockage of the ventilation channels.

[0022] S2: After the top layer of transparent culture medium has solidified, sow the wheat seeds of the variety to be tested. Before sowing, the seeds are disinfected and pre-germinated, and the sowing depth is 1-2 cm.

[0023] The transparent device also includes a lighting assembly. The lighting assembly includes a lamp and an L-shaped lamp post. One end of the lamp post is connected to the lamp, and the other end is connected to the top of the side wall of the transparent device, so that the lamp is suspended directly above the transparent device to provide light to the above-ground parts of the wheat. -2 ·s -1 .

[0024] The culture temperature is controlled at 15-25℃, the light cycle is 16h light / 8h dark, and the relative humidity is maintained at 60%-70%.

[0025] The transparent device also includes a light-blocking cloth. The light-blocking cloth covers the transparent device and is fixed to the connection point between the lamp post and the transparent device. The light-blocking cloth can be made of black opaque cotton cloth or a light-blocking material with a light-blocking rate of ≥95%. Normally, the light-blocking cloth is closed; it is only opened when it is necessary to observe the growth of the wheat roots, and then closed again after observation.

[0026] Since transparent culture media and transparent devices are prone to algae growth or light inhibition of the root system under light, setting up a shading cloth can effectively prevent external light from entering the substrate, ensuring that the root system grows normally in the dark environment, while also ensuring the convenience of observation.

[0027] S3: During the cultivation process, observe and record the growth of wheat roots through a transparent device. Recorded indicators include the maximum penetration depth of the roots and the root growth morphology. The maximum penetration depth is the depth of the transparent culture medium layer at the tip of the root. Growth morphology includes root thickness, number of branches, root tip color, and whether symptoms of salt damage such as blackening, rotting, and root hair loss appear. Observations are conducted once daily.

[0028] S4: As wheat grows, the roots penetrate downwards from the uppermost culture medium layer, passing through transparent culture medium layers of different salinities in sequence. When the roots stop growing downwards, or when obvious salt damage symptoms appear at the root tips, the transparent culture medium layer where the roots are located and its corresponding salinity are recorded. This salinity is determined as the salt tolerance threshold for this wheat variety.

[0029] Therefore, wheat varieties with higher salt tolerance thresholds can be screened out.

[0030] Taking a certain wheat variety as an example, on the 3rd day after sowing, the roots penetrated the transparent culture medium layer with a salinity of 0.1%, on the 5th day they penetrated the 0.2% layer, on the 8th day they penetrated the 0.4% layer, and on the 12th day the root tips reached the 0.6% layer. Continued cultivation until the 15th day showed that the roots had not penetrated the 0.6% layer, and obvious symptoms of salt damage, such as blackening of the root tips and loss of root hairs, appeared in that layer, while the roots in the 0.4% layer continued to grow normally and branched normally.

[0031] Therefore, the salt tolerance threshold of the transparent culture medium layer where the wheat root system stopped growing was determined to be 0.6%.

[0032] Example 2 The only difference between Example 2 and Example 1 is that the salt content required to prepare the transparent culture medium simulates the salt-alkali combined stress of inland low-lying saline-alkali land: by weight, NaCl:Na2SO4:NaCO3=5:4:1.

[0033] Taking a certain wheat variety as an example, after sowing, the root system stopped growing after reaching a depth of 0.8% transparent culture medium. Root tips in the 0.8% layer showed browning and root hair loss, while root growth in the 0.6% layer was basically normal. Therefore, the salt tolerance threshold of this wheat variety under simulated inland saline-alkali stress conditions is 0.8%.

[0034] As can be seen from the above embodiments, the present invention can simulate the corresponding salt stress environment for different types of saline-alkali areas by adjusting the salt composition in the transparent culture medium.

[0035] For coastal saline-alkali land, where the soil salinity is mainly chloride, the salt distribution ratio described in Example 1, i.e., NaCl:MgCl2:Na2SO4 = 8:1:1 by weight, can be used to evaluate the salt tolerance performance of wheat varieties under coastal saline conditions.

[0036] For inland low-lying saline-alkali land, where the proportion of sulfate in soil salt is high and often accompanied by alkaline stress caused by bicarbonate, the salt distribution ratio described in Example 2, i.e., NaCl:Na2SO4:NaHCO3 = 5:4:1 by weight, can be used to evaluate the salt tolerance performance of wheat varieties under combined salt and alkali stress.

[0037] Therefore, this invention is not limited to a single salt type, but can flexibly adjust the culture medium formula according to the salinity characteristics of the target planting area, thereby achieving precise screening of suitable wheat varieties for different ecological zones, and has strong versatility and practical application value.

Claims

1. A method for screening salt-tolerant wheat varieties, characterized in that: Includes the following steps, S1: In a transparent device, multiple layers of transparent culture medium are arranged vertically from bottom to top according to the salinity from high to low, and each layer of transparent culture medium is provided with multiple through-breathing channels; S2: Sow wheat seeds of the test variety in the top transparent culture medium and culture them. S3: Salt tolerance data of wheat root system's maximum penetration depth and growth morphology are observed and recorded through a transparent device; S4: As wheat grows, its roots penetrate downwards through different layers of culture medium with varying salinity. The salinity of the transparent culture medium layer where the roots stop growing or show obvious salt damage symptoms is located is determined as the salt tolerance threshold of the wheat variety, and salt-tolerant wheat varieties are screened out.

2. The screening method according to claim 1, characterized in that: The total salt content in the transparent culture medium, from bottom to top, by mass percentage, is 1%, 0.8%, 0.6%, 0.4%, 0.2%, and 0.1%.

3. The screening method according to claim 2, characterized in that: The total salt content includes sodium chloride: magnesium chloride: sodium sulfate = 8:1:1 by weight, or sodium chloride: sodium sulfate: sodium bicarbonate = 5:4:1, and one of the two ratios is selected.

4. The screening method according to claim 1, characterized in that: The ventilation channel is equipped with a ventilation pipe.

5. The screening method according to claim 4, characterized in that: A gasket is also provided between the adjacent transparent culture medium layers. The gasket is located at the air venting channel, and the air venting tube passes through the transparent culture medium layer and the gasket.

6. The screening method according to claim 5, characterized in that: The gasket has a ring structure, with the inner ring of the gasket wrapping around the vent tube and the outer ring of the gasket covering the gap between the vent channel and the vent tube; the vent tube has multiple vent holes on its wall and a non-woven fabric on its outer wall.

7. The screening method according to claim 1, characterized in that: The transparent device also includes a lighting assembly, which includes a lamp and an L-shaped lamp post. One end of the lamp post is connected to the lamp, and the other end is connected to the top of the side wall of the transparent device, so that the lamp is directly above the transparent device.

8. The screening method according to claim 1, characterized in that: The transparent device also includes a light-blocking cloth, which covers the transparent device and is fixed at the connection between the lamp post and the transparent device. The light-blocking cloth can be lifted or restored to observe the growth status of wheat roots.

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