Tobacco seed processing and attention points

Tobacco seed processing and processing is an indispensable technology for tobacco modern agriculture. It is the main technical means for further increasing the content of tobacco seed science and technology. Its popularization and application directly reflect the modernization level of tobacco seed work. Before the 1990s, due to technical limitations, traditional tobacco seed processing and processing generally used manual and common pesticides. In recent years, with the development of tobacco seed coating pilling technology and supporting nursery technology, tobacco seed processing and processing technology has entered a new era.

Treatment and processing of tobacco seeds are mainly through four methods to improve and improve seed quality. One is the separation of alien crops, weeds and inanimate impurities; the other is the removal of inferior seeds and the improvement of seed quality grades; the third is the application of plant growth agents, trace elements, and pesticides in the treatment of seeds to prevent disease transmission. And to improve the vitality of seeds; the fourth is to pack pills, improve the comprehensive resistance of tobacco seeds. In conclusion, the ultimate goal of processing and processing is to obtain tobacco seeds with high clarity, high vitality, high storability, and no pest infestation. The processing and processing of tobacco seeds mainly include: seed collection, threshing, drying, selection, grading, soaking, disinfection, re-drying, storage, coating pills, packaging, storage and transportation.

(I) Bare species treatment

1, the harvest and detachment of seeds

The seeds produced by the field's fine and colorful crops are brown in half of the twigs (50%), and the rest of the pods can also be turned brown to harvest the pods (seeds). After the harvest, the pods are air-dried in the drying area until the pods are completely dry. During this period, it is necessary to prevent the seeds from mildew due to moisture and poor ventilation, thereby affecting the quality of the seeds.

2, tobacco seed drying

Seed drying treatment is the premise of safe storage, and it is also an essential part of guaranteeing the quality of sowing. After fully dried seeds, their metabolism can be slowed, thereby prolonging the life of the seeds and maintaining a high germination rate. There is also the role of insecticidal and microbial inhibition.

(1) The basic principle of seed drying

Seeds are living hygroscopic materials and their structures are complex. Water is a ubiquitous basic component. Since the seed is a hygroscopic material, its water content depends on the relative humidity and temperature in the air, and the decisive factor in the relationship between the two is the water vapor pressure existing in the seeds and the surrounding environment. When the pressure of the steam in the seed is greater than the pressure in the surrounding environment, the moisture is emitted from the seed; when the steam pressure in the surrounding environment is greater than the pressure in the seed, the moisture enters the seed; when the steam pressure is equal, the seed The moisture content in the interior is basically in equilibrium with the moisture content in the surrounding atmosphere. According to this principle, to dry the seeds, the water in the seeds must be dispersed into the surrounding air. The rate of release of moisture from the seeds depends on the rate at which the seeds' moisture transfers from the body to the surface and into the surrounding air. The temperature of seeds, the temperature of the atmosphere, the physical structure and chemical composition of the seeds, and the permeability of the seed coats directly affect the rate of transfer of seed moisture from the center to the surface. At the same time, the saturation of the surface of the seed and the relative humidity and temperature of the air affect the rate of surface water dispersion.

Therefore, to reduce the seed moisture, there must be a certain temperature of flowing air through the seeds in order to receive good results.

(2) Factors influencing seed drying

a. Atmospheric pressure

The high pressure of the water evaporates slowly, the low pressure of the water evaporates quickly, and the evaporation of the water inside the seeds also occurs.

b, relative humidity

Under the condition of constant temperature, the relative humidity in the dry environment determines the seed drying speed and the water loss of the seed. If the relative humidity of air is small, for seeds with a certain moisture content, the driving force for drying is large, and the drying speed and water loss are large, and vice versa. However, the relative humidity in tobacco seed storage environment should be below 35%.

c, temperature

Temperature is one of the main factors that affect seed drying. The high temperature can, on the one hand, reduce the relative humidity of the air, and on the other hand it can promote the diffusion of moisture inside the seeds and evaporation of the surface moisture. However, under the storage conditions, the temperature of tobacco plants should not exceed 20 degrees Celsius, and the optimum temperature is less than 15 degrees.

d, air speed

During the seed drying process, adsorbed on the surface of the seed layer floating film, can prevent the surface of the seeds continue to evaporate water. With fast air flow, the seed dries quickly.

In the seed drying process, there is a certain relationship between temperature, humidity, and air flow rate. The higher the temperature, the lower the relative humidity, and the faster the air flow rate, the better the drying effect. However, for tobacco seeds, it must be ensured during the drying process that it does not affect seed vigor, otherwise it loses the significance of seed drying.

(3) Methods for Drying Tobacco Seeds

Tobacco seeds are naturally air-dried, sun-dried, and mechanically dried.

a, naturally dried

The natural air dryness of tobacco seeds mainly refers to the fact that after the harvest, the branches of fruits are naturally air-dried in a professional air-drying room, and the other function of natural air-drying is the ripening of seeds, which is conducive to further improving the quality of seeds. The natural drying time is generally 15-25 days.

b, drying

Drying is the easiest way to dry tobacco seed. Drying should be done on a sunny day. It requires high temperatures and sufficient light. It is usually dried for 2-3 days. Drying can not only reduce seed moisture but also kill some germs and activate enzymes in the seeds. Activity (see Table 1).

Table 1 Dead temperature of tobacco seed pathogens

Name of disease lethal temperature (C) Time (minutes)

Bacterial wilt 52 10

Anthrax wet 55 5

Bluestar Disease Wet 50 5

Wildfire 49 to 50 10

Black disease 47 10

c, mechanical drying

There are many equipments for seed drying, but the current practice experience is the use of mechanical baking equipment for flue-cured tobacco. For many years, Yunnan has used the “Baking” series roasting machines of Beijing Puzhao Company. The first is that the tobacco season is used to modulate the tobacco; the second is when the seeds are harvested and used for dry storage; and the third is when the coated seeds are used for drying the coated species during production. The drying temperature of tobacco naked seeds and coating seeds was controlled between 40-42C and the temperature difference was 4-6C. Do not open the vents. The time is 5-6 hours, the water content of naked seeds is below 7%, and the moisture content of the coating species is below 5%. 3. The selection of seed selection for tobacco seed is to use the physical characteristics of the seed to remove the different crops, weeds and inanimate impurities. The use of light, heat, electricity and other methods to inhibit pathogens, maintain seed health, improve Seed vigor and seed quality. The physical characteristics of seeds mainly refer to the size (width, thickness, and length), weight (thousand-grain weight), surface characteristics, color, and electrification properties of the seeds.

(1) Screening

After the tobacco seeds were harvested, they were screened first, 30 mesh copper sieves were used to separate large particles (tablets) of impurities, and 50-60 mesh copper was used to sieve over small particles (tablets) of impurities and fine dust.

(2) Wind selection

Due to the fineness of tobacco seeds, there are still some impurities with the same seed size after screening.

The difference is not so big, it is difficult to remove, because the generally sick seeds can not be fully matured or even matured to form pods, so it is lighter than the healthy (non-disease) seeds. At this time, the method of removing winds is used to remove impurities and pods. Small bellows and large bellows are generally used.

(3) Water selection

Water selection uses different specific gravity to separate impurities and pathogens from seeds. Tobacco seed water selection is generally soaked in a large basin or in a tank for 6-8 hours before or before sowing, wherein the seeds are soaked one or two times per hour. Water selection can generally be combined with soaking of medicinal products.

(4) Machine selection

Machine selection is a method of selecting seeds using specialized machinery. According to the actual conditions of each place, seed selection is performed using seed selection instruments that meet their own conditions.

4. Diseases and disinfection of tobacco seeds

Seeds are one of the most important pathways for the transmission of tobacco pathogens. Usually, seed diseases include the presence of pathogens on the surface or inside of seeds and the direct or indirect mixing of pathogens or pathogens of latent pathogens between seeds. The main hazards: one is to harm the seed itself, and the other is to spread the disease. The rate of seed flu disease is determined by the severity of the disease and the conditions of seed treatment and processing. The severity of disease transmission depends on the seed flu disease rate and the suitability of environmental conditions in the current year. One of the purposes of tobacco seed processing and processing is to reduce the occurrence of tobacco diseases through a series of operations control and disinfection of seeds. Therefore, the prevention and control of tobacco diseases must first establish the concept of "healthy" seeds and do a good job in the processing and processing of seeds.

(1) Seed diseased parts

Diseases infested by many tobacco systems have pathogens in all parts of the plant. Pathogens can invade from different parts of the seed in different ways, so any part of the seed can transmit pathogens.

a. Embryonic colonization

b. ovule carrier

c. Endosperm invasion

d, seed coat invaded

e. The skin is affected

f. Invasion of branches and stems

g. Contamination of seeds in seeds

Table 2 Investigation of Main Diseases of Tobacco Seed Production

Pathogenic pathogenic sites

1 tobacco wildfire disease with bacteria in seeds

2 tobacco anthracnose conidia adhere to the seed surface, dormant mycelium in the seed

3 tobacco brown spot spores, hyphae on capsules and seeds

4 Tobacco leaf spot pathogenic bacteria in seeds

5Tobacco mosaic disease (TMV) diseased leaves and stem fragments can be spread among seeds

6 Tobacco downy mildew oospores or mycelium mixed in seeds

7 Tobacco Rupture Virus Disease Mustard, Amaranth Seed Internal

8 Tobacco etch virus disease virus plasmid in tobacco seed coat

9 Tobacco ringworm virus virus in seeds

10 Tobacco Blight Pathogenic Bacteria Latent Seeds Internal

11 Tobacco seed black disease conidia attached to the species table, mycelium lurking inside the seeds

(2) Seed diseased species

Seeds are important sites for the wintering and summering of various pathogens. Generally speaking, they are the primary source of infection for tobacco diseases. With the transfer of seeds, pathogens can spread without any end. About 30,000 plant diseases are known to be caused by fungi. According to Richardsoh's “Inventory List of Disease-borne Diseases,” there are more than 100 genera and more than 1,000 species of species of faecal bacteria, and about 300 diseases are caused by bacteria. Twenty-nine species of seedlings were transmitted, of which 75 species were transmitted by seeds. The third type is virus transmission.

(3) Major diseases of tobacco propagation (see Table 2 for details)

5, seed packaging, storage and transportation

Refer to the relevant requirements of the "People's Republic of China Industry Standard" issued by the State Tobacco Monopoly Bureau:

(1) Packaging

The selected and sterilized naked species are cleaned, non-polluted, odor-free and moisture-proof materials and equipment (cotton bags, kraft paper bags, desiccators, refrigerated cabinets, etc.) and stored after being packaged.

Seed packaging should be printed, posted, or affixed with a label, indicating the name of the species, seed category (original or improved), grade, weight, origin, date of production, and the full name of the operating organization.

(2) Storage

a. Warehouse and equipment

To choose a high-rise, dry sunny place to build a warehouse, require solid security, no leakage, doors and windows can be closed, can ventilate, there are moisture-proof facilities, there are storage racks. It is forbidden to stack flammable and explosive materials, chemical fertilizers, pesticides, and other materials unrelated to seeds; warehouse equipment and instruments (ventilation and dehumidification equipment, temperature measurement, moisture meter, fire-fighting equipment, etc.) must be provided.

b. Manage special personnel management, regularly or irregularly check (storage library environmental condition inspection, seed quality inspection, etc.), and do a good job of registering seed storage and post-processing.

c. Diseases, pests and rodents control

(3) Transportation

a. Each batch of seeds must be accompanied by a “seed inspection certificate” indicating the full address and zip code of the shipment, receiving unit or individual;

b. Transport tools must be clean and dry, with rainproof equipment to prevent oil stains;

c, transport packaging requires bagging, marking layers, bags, boxes require strong and durable;

d. During the transportation process, prevent moisture, rain, chaos, and damage;

e. In the course of transportation, if problems (damp, damage, confusion, etc.) are found, they should be dealt with promptly;

f. The receiving unit checks the relevant documents to get the goods.

(B) Seed coating production

Tobacco seed factory processing process (Figure 5-3-3)

1. Coating Pill Technology of Tobacco Seeds

(1) Function and Function of Tobacco Seed Coating Agent

a, protection, repellent effect.

b. Internal absorption and conduction.

c, slow release effect.

After pilling the tobacco seeds (hereinafter referred to as coating), the resistance of the tobacco seeds is improved, and each tiny seed has its corresponding value.

The main functions are:

a. After coating, normalize, granulate, and commercialize fine varieties of tobacco, and perform precision seeding.

b. Comprehensive prevention and control of certain early stage seedling growth, insect pests, and disease deficiencies.

c, promote rooting, such as adding some hormones, can stimulate plant growth, make their seedlings robust.

The coated seeds are sowed in the soil and the seed coat forms a protective screen around the seeds. The pesticides and fertilizers are slowly released from the underground “small nutrient stores” and “small drug stores,” and are smoked by the tobacco plants and transmitted to the site of the ground for promotion and protection. effect.

2. Physical, chemical and biological properties of tobacco seed coating agent and its coating on tobacco seeds

(1) Appropriate pH (PH) This is based on the range of pH values ​​suitable for germination, growth, development, and storage of tobacco seeds and for their efficacy. The appropriate pH should be between 5.5-7.

(2) Appropriate viscosity and fastness

The viscosity and the degree of fastness of the binding agent binder to the tobacco product should not be too high or too low. The threshing rate of the coated seeds does not exceed 3%, and the pressure resistance of single seeds should not be less than 150g.

(3) A good film-forming seed agent can quickly solidify and form a film after being coated with tobacco seeds, so as to facilitate production, and seed particles and particles do not adhere to each other.

(4) Storage stability and safety

After the tobacco seeds are coated, they are required to have a room temperature of 300C. When they are insoluble, they will not freeze when they are insoluble in 00C. The active ingredients do not decrease. They are safe to seeds and do not affect seed vigor. They have the following two aspects:

a. The water content in the coating layer does not exceed 8%.

b. Proper proportion of active ingredients (fertilizers, pesticides, hormones, etc.) does not affect seed germination.

(5) Good sustained-release seed coats can breathe and have rewarming properties. Seeds coated in soil can only absorb and not dissolve in water.

(6) Effectiveness of coated seeds

The coated tobacco seed rate is not less than 98%, and the single grain rate is not less than 95%. That is, the effective seeds and the number of effective seeds of the tobacco seeds in the coated seeds.

(7) Appropriate degree of lysis and better lysis rate

Refers to the degree of lysis of a single coated seed within a certain period of time and the number of lysis of a certain number of coated seeds. The degree of cleavage is preferably 80-90% of the area of ​​the individual grains. The lysis rate is preferably 100%.

(8) High purity

Here is the meaning of two aspects: First, refers to the purity of the raw materials used in seed coating agent, the active ingredient used, that is, the active ingredient content of the raw material is higher. The second is that the purity requirements of tobacco seed varieties meet relevant standards. Generally the original coating should be used.

(9) Better germination power means that the difference in germination force between the coated seed and the uncoated seed at the same level and conditions should not reach a significant level.

(10) The higher biological activity of the control object is generally a higher control effect on the designated control object.

(11) Mechanized production means that seed coating agents can adapt to mechanized production and produce qualified coated seeds.

3, the tobacco seed itself should have the conditions The quality of tobacco seed coating products, including the quality of tobacco seeds itself (that is, the quality of uncoated species), you should have the following conditions:

(1) Must use the identification and promotion of fine varieties. If untested and promoted new varieties, good strains (strains), and seeds for heterosis use are applied as trials or demonstrations for application, professionals must be responsible for coating.

(2) The production of coating must be carried out according to the characteristics of good varieties to ensure the economic and utilization value of the coating.

(3) It must be used after inspection to confirm that the purity is high, after the processing of selected seeds, to avoid artificial mechanical mixing and the use of seeds with low vitality.

4. Tobacco seed mechanical coating

Tobacco seed machinery should have the conditions:

(1) The tobacco fine seed coating should be arranged in a centralized manner and be carried out in the seed base or seed processing and processing factory. The reason is that the first kind of coating is a complex of pesticides, chemical fertilizers, composite materials, and seed treatment, and it is safe and technical. Consider the need for specialized technical personnel to master. Secondly, it focuses on production, facilitates management, facilitates technology concentration, and facilitates the development of new products suitable for tobacco production. Once again, because dispersal production is limited to seasonality, it is easy to waste manpower and material resources, and product quality is difficult to guarantee.

(2) Mechanical coating process operation

The predetermined amount of tobacco seeds is poured into the coating machine, and then the rotary switch is activated. After the rotation is stabilized, the coating agent is applied after being sprayed with the binder having a certain concentration, and the molding is repeated several times to form the coating. Can add a predetermined amount of fungicide, when the coated seed diameter of 1.2mm, then add the specified proportion of fertilizer, insecticide and coating agent until the diameter of 1.5 - 1.8mm, then apply a certain coating agent shaping diameter is 1.8-2.0mm. Then package the seeds in the pan of the coating machine and rotate and polish it for 20 minutes. Add the colorant solution and the adhesive. Control the temperature to not exceed 300C, blow air to dry, and then remove the coated seeds for natural drying or mechanical drying. After inspection, packaging machines (polyester, aluminum foil or polyethylene composite film) are used to quantify the packaging according to the production needs of the packaging machine, and finally transferred to the finished product warehouse.

5. Safety precautions when using coated seeds

(1) Coated seeds As a means of production for tobacco production, attention should be paid to the use of propaganda to prevent ingestion, and do not use sprays to avoid poisoning.

(2) The coating seeds of various formulations are special for seeds and also used as styling products. It is not necessary to add other fertilizers and pesticides as additional coatings or to add alkaline fertilizers and pesticides to the seedbed during sowing so as to avoid the failure or cause of coating. Crop injury. No fertilizer is allowed to be applied before the general seedlings cross.

(3) Do not smoke or eat food when using coated seeds. Wash your face and hands with alkaline soap after work.

6, how to determine the precise seeding rate of coated seeds

(1) Seedling volume of conventional nutrition bag nursery

The precise seeding rate of coated seeds is based on several years of experimental data. Mainly based on the field emergence rate, seedling planting seedlings can be used seedlings, coated seeds 1000-grain weight basis, and refer to the final available seedlings on the net area of ​​4-5 square meters seedbed per acre field. The specific seeding rate (grams) should be calculated according to the 1000-grain weight of the coated seeds. The current grain-size multiples of the tobacco-coated seeds are 5 grams of 2 grams, 4 grams, 6 grams, 8 grams, and 10 grams. If the grain weight is 4 grams, , 16-20 grams per square meter, 1000 grams weight 8 grams, it takes 32-40 grams, and so on. For example, good field management, high seed quality, and a 70% emergence rate

Around, this can reduce the number of sowing, but generally the net area per square meter of seedbed should not be less than 900.

(2) Floating Seedling, Wet Seed Seeding Rate

The use of floating trays or wet tray seedlings, generally every hole (hole) sowing 1 to 2 kinds of coating to ensure the production of seedlings.

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