CN-121986624-A - Low-temperature corn seed germination rate improving method based on plasma

CN121986624ACN 121986624 ACN121986624 ACN 121986624ACN-121986624-A

Abstract

The application discloses a low-temperature corn seed germination rate improving method based on plasma, and aims to solve the problems of low germination rate and low uniformity of corn seeds in a low-temperature environment. The method is characterized by comprising the steps of placing seeds subjected to moisture regulation in a fluidized bed reaction cavity, filling argon-oxygen-nitrogen mixed gas with a specific proportion, treating the seeds by using non-thermal balance plasma generated by a DBD power supply according to three continuous gradient stages of surface etching, signal induction and energy steady state, and carrying out real-time feedback regulation by combining an emission spectrometry. By adopting the technical scheme, the application can effectively excite the endogenous cold stress resistance reaction of the seeds, remarkably improve the low-temperature germination rate, the germination potential and the later root growth potential, and has the advantages of high treatment efficiency, good consistency and environmental friendliness.

Inventors

YU TAO
SUN MINGHAO
ZHANG JIANGUO
LI WENYUE
YANG GENGBIN
MA XUENA
CAO SHILIANG
LI XIN
LI SINAN
LI YUNLONG

Assignees

黑龙江省农业科学院玉米研究所

Dates

Publication Date: 20260508
Application Date: 20260319

Claims (10)

1. The low-temperature corn seed germination rate improving method based on the plasmas is characterized by comprising the following steps of: Firstly, mechanically screening corn seeds to be treated, regulating and controlling the moisture of the screened corn seeds, and regulating the total moisture content of the corn seeds to a reference interval of 12-14% in a circulating hot air drying or ultrasonic atomization humidifying mode; Step two, placing the pretreated corn seeds in a reaction chamber (1) of a plasma reaction device, starting a rotary fluidized bed structure (2) integrated in the reaction chamber (1), and enabling the corn seeds to realize fluidization rolling under the coupling action of centrifugal force and gravity, so as to ensure that 360-degree omnibearing plasma exposure is realized on the surfaces of the seeds; Step three, reducing the background pressure in the reaction chamber (1) to be below 100 Pa by a dry rotary vane pump (7), and then introducing working gas into the reaction chamber (1) by a mass flow controller (8); Starting a DBD power supply (6), wherein the DBD power supply (6) adopts a bipolar high-frequency high-voltage pulse modulation mode, the output peak-to-peak voltage is set to be 15 kilovolts to 25 kilovolts, the pulse frequency is 8 kilohertz to 12 kilohertz, the duty ratio is 15 to 25 percent, and non-thermal balance plasma with the electron temperature of 1 to 10 electron volts and the heavy particle temperature close to the room temperature is generated; And fifthly, carrying out three continuous energy gradient stage treatments on the corn seeds through the DBD power supply (6), wherein the first stage is a surface etching stage, the high-energy particle bombardment is utilized to carry out micron-scale etching on the waxy layers on the surfaces of the seed coats, the second stage is a signal induction stage, the active oxygen nitrogen species are induced to diffuse into the seeds and activate stress-resistant signal transduction paths by optimizing the generation efficiency of the active oxygen nitrogen species, and the third stage is an energy steady-state stage, and the third stage is used for stabilizing polar groups on the surfaces of the seed coats.
2. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein in the step one, the complex dielectric constant imaginary part of the corn seed coats is matched with the subsequent high-frequency electric field of the plasma by adjusting the moisture content, so that the active particles generated by the plasma are guided to diffuse to the seed coats deeply by utilizing the distribution of moisture in the micropore structures of the seed coats on the premise of not causing thermal damage to the embryo parts of the corn seeds.
3. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein in the second step, the rotary fluidized bed structure (2) is controlled by a central PLC system (9) to drive a servo motor to perform constant rotation speed control, and the rotation speed is selected based on the average particle size and quality of corn seeds, so that centrifugal rolling state formed in the rotation process of seeds can eliminate discharge shadow effect generated by different seed loading capacity, and uniformity of seed treatment of each batch is ensured.
4. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein in the third step, water vapor with volume fraction of 0.5-1% is additionally added into the working gas, and hydroxyl free radicals generated by dissociation of water molecules under high-energy electron impact are utilized to accelerate degradation of lignin structures of seed coats and enhance hydrophilicity of seeds, so that swelling time of the seeds in low-temperature soil is shortened by more than 18%.
5. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein in the fourth step, the circuit topology structure of the DBD power supply (6) adopts a full-bridge inversion architecture based on insulated gate bipolar transistors, boosting is achieved through a high-frequency transformer, the power supply system integrates a multi-stage LC filter network and an active shielding layer to inhibit electromagnetic interference, and rising edge time of the pulse waveform is controlled within 50-100 nanoseconds to improve efficiency of energy coupling to an active species excitation channel.
6. The method of increasing germination rate of low temperature corn seeds based on plasma according to claim 1, wherein in the fifth step, the first stage is a surface etching stage, the duration is 60 to 90 seconds, the average discharge power density is controlled to be 0.8 to 1.2 watts/square centimeter, and the micro-grooves with the depth of 2 to 5 micrometers are formed on the surface of the seed coat by physical bombardment of argon ions and oxygen ions, so that the static contact angle of the seed coat is reduced to below 45 degrees.
7. The method of claim 1, wherein in the fifth step, the second step is a signal induction step with a duration of 120 to 180 seconds, and the process control logic is to control the central PLC system (9) to instruct the voltage amplitude to be reduced by 15% and to increase the pulse frequency to 12 kHz at the same time, thereby optimizing the efficiency of generating superoxide anions and nitric oxide to permeate into the plasma in the seed coat to activate the mitogen-activated protein kinase cascade pathway in the cytoplasm.
8. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein in the fifth step, the third stage is an energy steady-state stage, the duration is 30-60 seconds, and a weak discharge field is maintained by adopting an extremely low duty ratio pulse of less than 10%, so that oxygen-containing and nitrogen-containing polar groups newly generated on the surface of the seed coat in the first stage and the second stage are stabilized through chemical bonding, and the failure of active sites in the subsequent storage process is delayed.
9. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein, The method further comprises the step six of utilizing a real-time online monitoring system based on an emission spectrometry to carry out closed-loop control in the treatment process, capturing characteristic spectral lines of active species in a discharge area through an optical fiber probe (5), and automatically compensating input voltage according to spectral intensity feedback to ensure that the flux fluctuation rate of active particles is lower than 3%; In the sixth step, the real-time online monitoring system calculates the intensity of the reduced electric field in real time by monitoring the hydroxyl band with the wavelength of 309.1 nanometers and the oxygen atomic spectrum line with the wavelength of 777.4 nanometers by using an expert system based on the coupling of a Boltzmann equation and a chemical kinetics model, and dynamically adjusts the inversion frequency of the DBD power supply (6) by a PID algorithm.
10. The method for improving germination rate of low-temperature corn seeds based on plasma according to claim 1, wherein, After the treatment is finished, placing the seeds in a controlled environment with the temperature of 20 ℃ and the humidity of 40%, standing for 12 to 24 hours, and performing a post-treatment stabilization procedure to form a stable stress-resistant memory effect; The post-treatment stabilization procedure is characterized in that the post-treatment stabilization procedure is carried out by standing under a controlled temperature and humidity environment, the expression of heat shock protein chaperone molecules in the seeds is induced, and the cross protection mechanism is utilized to ensure that the metabolic key enzymes in the seeds keep the spatial conformational stability in a low-temperature environment below 10 ℃, so that the final germination rate of the corn seeds in the environment of 10 ℃ is improved by more than 15%.

Description

Low-temperature corn seed germination rate improving method based on plasma Technical Field The invention belongs to the field of seed treatment, and particularly relates to a low-temperature corn seed germination rate improving method based on plasma. Background Corn (Zea mays l.) is used as a core crop with both grain, feed and industrial raw material properties worldwide, and the stability of yield and quality are directly related to the robust operation of national grain safety and agricultural industry chains. In northern spring sowing areas and high-altitude planting zones in China, the development of climate characteristics and cultivation systems is limited, and corns are often subjected to severe low-temperature stress at the initial stage of sowing. Because corn belongs to warm-loving crops, the germination period of seeds can be obviously prolonged due to the lower soil temperature, and the phenomena of hindered conversion of nutrient substances in the seeds, damage of biological films, aggravation of pathogenic bacteria infection, low emergence rate, weak seedling vigor, poor uniformity of plants and the like are caused, so that the subsequent growth and development and the final yield are irreversibly and negatively influenced. To address this challenge, those skilled in the art have long sought to explore effective means of improving seed stress resistance. The traditional seed pretreatment scheme mainly comprises physical seed soaking, chemical agent induction, biological coating technology and the like, and aims to enhance the tolerance of seeds in a low-temperature environment through exogenous nutrition supplement or intervention of growth regulators. With the continuous evolution of physical agriculture technology, the non-thermal plasma treatment technology gradually becomes a research hot spot in the field of agricultural scientific research due to the remarkable advantages of green environmental protection, no chemical residue, short treatment time and the like. The technology utilizes high-energy electrons, ions, excited atoms and high-activity oxygen nitrogen free Radicals (RONS) generated in the gas discharge process to carry out complex physical and chemical interactions with the seed surface. Specifically, the effect can etch the seed coats in micro-nano scale, effectively increase the surface roughness and introduce polar groups, thereby obviously improving the hydrophilicity of the seeds and laying a physical foundation for the moisture adsorption and the start germination of the seeds in soil. However, by analyzing feedback from deep applications of the prior art in actual production conditions, it can be found that although the plasma-based surface modification technique can effectively shorten the seed swelling time under normal temperature or ideal environment, there are significant technical contradictions and limitations on principle level when dealing with extreme or continuous low-temperature germination scenarios. First, the inhibition of seed germination at low temperatures is a complex process involving physical, biochemical and molecular levels, and the core bottleneck is often not only the rate of moisture penetration of the seed coat, but also the deeper reason is that the activities of antioxidant enzyme systems (such as superoxide dismutase SOD, peroxidase POD, etc.) inside the seed are extremely inhibited in low temperature environments, resulting in retardation of energy metabolic pathways and imbalance in intracellular homeostasis caused by accumulation of Reactive Oxygen Species (ROS). Most of the existing plasma treatment methods focus on improvement of physical properties of seed coats, but lack of consideration on deep excitation of signal transmission channels and physiological metabolism networks in seeds, and it is difficult to construct endogenous barriers against low-temperature cold injury from the biological mechanism level. Second, there is an extremely severe "energy threshold" balance problem during plasma processing, which is particularly pronounced in low temperature stress environments. In order to achieve the effect of improving the low-temperature germination rate, high-dose plasma intervention is often required to generate enough physiological stimulus, but because the embryo tissue of the corn seed has high sensitivity to external physical stress, the high-density active particle flow breaks through the protection limit of the seed coat very easily under the special working condition that the self-repairing capability of the seed at low temperature is obviously weakened, and causes direct oxidation damage to embryo and radicle primordium, so-called 'over-treatment' phenomenon is generated, and the rotten seed rate at low temperature is aggravated. In addition, when the conventional plasma treatment device is used for treating corn seeds in a large quantity and irregular shape, the problems of uneven distribution of the electric discharge f