From tobacco sowing to grading

Tobacco cultivation techniques are as follows:

I. Environmental conditions for tobacco growth

1, Temperature: Tobacco is a thermophilic crop, which can grow in the range of 8-38℃ above the ground. The optimum temperature for growth and development is 25-28℃, and the tobacco plant will die at minus 2-3c. The underground part can grow at 7-43℃, but the optimum temperature is 365438 0℃. The optimum temperature for seed germination is 24-29℃, the lowest temperature is 7.5- 10℃, and the highest temperature is 35℃. When the temperature is lower than 7.5℃, the seed germination process stops; Above 30℃, the germination process is slow; If the temperature exceeds 35℃, the germinated seeds will gradually lose their vitality. Generally, the transplanting period of tobacco should be after late frost, the temperature should not be lower than 65438 00℃, and the ideal daily average temperature of leaf maturity should be around 24℃ for 30 days, so as to produce high-quality tobacco leaves.

2. Moisture: Generally, water is needed in the early stage of growth, most in the middle stage and less in the later stage. The soil moisture should be kept at about 70% of the field capacity in the seedbed stage, and the water supply should be stopped for seedling hardening 10- 15 days before transplanting. Transplanted to seedling stage, the leaf transpiration is small, the average daily water consumption is 3.5-6.4 mm, and the average daily water consumption from seedling returning to tree gathering stage is 6.6-7.9 mm, and the soil moisture should be kept at 60% of the field capacity. Below 40%, the growth will be hindered, and above 80%, the root growth will be poor, which is not good for the later growth. From clumping stage to budding stage, the average daily water consumption is 7. 1-8.5 mm, and it is appropriate to keep the soil moisture at 80% of the field capacity. At this stage, if there is a lack of water, the growth will be hindered, and if there is a long-term drought, there will be premature flowering or premature drying. From budding stage to mature stage, the average daily water consumption is 5.5-6. 1 mm, and the soil moisture should be kept at 60% of the field capacity, and the moisture is slightly less at this stage to improve the quality of tobacco leaves. If there is too much soil moisture, it is easy to delay maturity and reduce quality.

3. Sunshine: Tobacco always needs sufficient sunshine, but most varieties are not strict about the length of sunshine. Flue-cured tobacco needs sufficient sunshine in the growth period, but it is not very strong. The daily sunshine time is 8- 10 hour, especially in the mature period. Adequate sunshine is a necessary condition for producing high-quality tobacco leaves. Sunny days with short wave components are beneficial to improve the quality of tobacco leaves.

4. Soil: Although tobacco can grow on various types of soil, the requirements for planting high-quality tobacco are strict. Red soil is the best, followed by red loess, sandy soil and mixed soil, and tidal soil (black soil) is the worst.

5. Weather phenomenon: gale and hail weather do more harm to tobacco leaves than any other crops, which may cause serious losses in seedbeds or fields. Therefore, tobacco cannot be planted in areas where strong winds and hail often occur during the tobacco growing period.

Second, tobacco planting management

1. Seedling raising: Before accelerating germination, tobacco seeds should be exposed to sunlight at 15-20℃ for 2-3 days to improve germination potential and germination rate. To cultivate strong seedlings, one is to adopt the new technology of double-layer film paper tube seedling raising. The paper tube is not less than 4 cm in diameter and 6-7 cm in height. There are 625 seedlings per square meter, and a seedbed of 10 square meter can be planted in 4 mu of tobacco field. The second is to prepare nutrient soil, with 60% field soil and 40% decomposed pig manure as the matrix, which needs about 0.8- 1 m3 per border, and then add 3-4kg compound fertilizer after disinfection. Third, timely early sowing and early transplanting can increase yield by 20% and improve quality by 25%. Huanghuai tobacco-growing areas should be planted from spring to mid-February. Four, seedbed management, due to the low temperature when sowing, vulnerable to low temperature hazards, should be adjusted in time according to the requirements of tobacco seedling growth on temperature and humidity. Generally, it is carried out twice, the first time after the "delivery date", the seedling spacing is 1.5-2cm, and the second time the seedling spacing is 6-8cm.

2. Transplanting: timely and early planting is the key to producing high-quality tobacco leaves. The best transplanting period in Huanghuai tobacco-growing areas should be completed before Qingming to Grain Rain. The planting density should be controlled at per mu 1200- 1300 plants. Planting tobacco with plastic film mulching can not only increase temperature and preserve moisture, but also improve the drought and waterlogging resistance of tobacco plants and prevent tobacco black storm. If it rains thoroughly before transplanting, it can be covered with plastic film in time to keep warm after the rain. If it doesn't rain, you should bring water from the soles of your feet when planting cigarettes, and cover them tightly with plastic film after planting cigarettes (if you plant cigarettes before and after Qingming Festival, because the temperature is low, you can cover the seedlings with plastic film first, and then cut the plastic film after the temperature is stable, take out the tobacco seedlings and seal the film at the roots to prevent water loss).

3. Field management: The most prominent problem in flue-cured tobacco production is the contradiction between yield and quality. Generally speaking, the higher the output, the worse the quality, but not the lower the output, the better the quality. Therefore, management should strive to stabilize production and ensure quality. ① Suitable fertilization: base fertilizer is the main fertilizer, and new balanced fertilization technology is adopted. Before transplanting, the amount of pure nitrogen fertilizer per mu was 6 kg in low-fertilizer field, 5 kg in middle-fertilizer field and 3-4 kg in high-fertilizer field, and the suitable ratio of nitrogen, phosphorus and potassium fertilizer was 1: 2: 3. When fertilizer deficiency is found in the middle and late stage, foliar spraying is used for topdressing. ② Irrigation and drainage in time: When the tobacco field is dry during the critical period of tobacco water demand, sprinkling irrigation 1-2 times can increase the yield by 8. 1-43. 1% and improve the quality. The tobacco field was waterlogged for 1-2 days, and the yield was reduced by 47.8-65%. Pay attention to ditch cleaning and drainage in low-lying tobacco fields or rainy seasons. ③ Pay attention to intertillage and soil preparation: intertillage in time under drought conditions is of great significance for water conservation. Timely intertillage after rain can reduce soil moisture, increase soil permeability, increase ground temperature and promote root growth. Farming can also eliminate weeds and reduce pests and diseases. Combined with intertillage, timely soil cultivation can promote new roots, expand the ability to absorb water and fertilizer, be beneficial to drainage and waterlogging prevention, and enhance the ability to resist drought, wind and lodging. ④ timely topping and raking: topping and raking can not only increase the yield by 365,438+0-49%, but also be the main way to improve the quality of tobacco leaves. Topping should generally be done in two times according to the number of leaves left, so as to promote the orderly growth and uniform yellowing of tobacco plants and facilitate baking. The branches should be cleared in time. ⑤ Strengthen pest control: give priority to prevention, and combine chemical control with manual killing.

3. Mature harvesting is one of the important links of high-quality tobacco production. The characteristics of tobacco ripening are: the leaves change from green to yellow-green, the hairs on the leaves fall off, and the angle between leaves and stems increases (about 90 degrees). Only when the main veins of the lower leaves are white, the branches of the middle leaves are white, and the main branches of the upper leaves are white, and yellow spots appear on the leaves, can they be harvested and baked. The above contents are for reference only.

grade

The first is to pick wool samples, with a wide range. The selection and preparation of wool samples is the basis of making tobacco standard samples. Without sufficient, diversified and representative standard sample materials, it is difficult to make a set of tobacco standard samples that meet the requirements of "national standard". When selecting wool samples, the key is to select a wide range, sufficient tobacco leaves and sufficient representativeness, and tobacco leaves with different parts, colors, lengths and maturity should be selected into wool samples. This is convenient for making more complete tobacco standard samples. The second is to choose again and be cautious. Because the appearance quality of tobacco leaves is continuous, the color characteristics and other appearance characteristics of tobacco leaves with different cultivation and modulation levels sometimes show different regularity, so some appearance characteristics of tobacco leaves are specious and difficult to judge. If these tobacco leaves are selected into the sample, it is easy to confuse the position, color boundary and grade boundary, and finally make a set of unqualified samples. Therefore, after selecting wool samples, secondary sorting is needed. In the secondary sorting process, special tobacco leaves should be removed to lay the foundation for the next grouping.

The third is to set the position and compare the color. After secondary sorting, wool samples should be selected in groups first. According to the position and color of tobacco leaves and the main characteristics of tobacco leaves. The focus of grouping is parts and colors, among which grouping parts is the key, and parts are wrong, which are all mistakes. The parts are mainly divided into vein phase and leaf shape, and the lower, middle and upper leaves are distinguished according to color, thickness and leaf surface characteristics. Then according to the depth of color, it is easier to distinguish the color of the same part, and according to the characteristics of the part and color, the lower lemon yellow and orange groups are divided. Central lemon yellow and orange group; The upper layer is lemon yellow, orange yellow and the upper layer is reddish brown. In the case of high production level, it is necessary to separate mature leaf groups; According to the requirements of "national standard" and the characteristics of tobacco leaves in subgroups, they are divided into five subgroups: upper mottled, middle mottled, lower mottled, smooth leaves, slightly turquoise and bluish yellow.

Fourth, there are many factors and many grades. There are six quality factors of tobacco leaves, namely maturity, leaf structure, identity, oil content, chromaticity and length. How to correctly grasp and use these six quality factors in the scoring process, the author's experience is: maturity is divided into major categories. All mature leaves were placed in the positive group (except X4F and X4L), and vice versa. Leaf structure is closely related to maturity and can be ignored. Oil content and chroma are the most critical. Oil content and chromaticity are the most significant factors to distinguish the internal quality and external quality of tobacco leaves. Oil is divided into four grades: more, more, less and less, and chromaticity is divided into five grades: strong, strong, medium, weak and light. If different grades are separated, the general grades are separated. The leaf length is different, and it should be shortened from high to low. It should be noted that the leaf length of the minimum and maximum limited tobacco leaves of a grade should not be lower than the minimum standard requirements of that grade. Parts can also be graded. Part is the primary factor of grouping and sometimes the key factor of scoring, and some parts have a certain corresponding relationship with scoring.

Fifth, the border is clear and the number is sufficient. Among the graded tobacco leaves, the tobacco leaves with medium quality are selected first, and then the tobacco leaves with good quality (upper limit) and poor quality (lower limit) are selected. When synthesizing tobacco standard samples, the middle leaves of each grade should be the main ones, and the better and worse leaves of the same grade should be reasonably matched. There should be some differences in the quality of adjacent grades of tobacco leaves, and the boundaries should be clear. We often see that some grade standard samples formulated by individual units have only 4-7 leaves or even less, which is not representative. The national standard stipulates that the number of flue-cured tobacco leaves per stalk is 20-25. The number of blades of standard samples of each grade must meet this requirement, otherwise it is not representative.