Tobacco (Nicotiana tabacum) is an alkaloid crop, also considered one of the most labor-intensive industrial crops.
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Economic importance
Tobacco is grown for its leaves, which are used as a raw material in the manufacture of cigarettes, cigars and pipe tobacco.
Tobacco leaves contain:
- nicotine 1-3%;
- essential oils – about 1%;
- resins – 4-7%;
- proteins – 7-10%;
- carbohydrates – 4-13%;
- ash – 13-15%.
The smell and aromaticity of tobacco are due to resins and essential oils.
Nicotine is synthesized by the root system of tobacco plants. This was proven by Academician A.A. Shmuk in 1941 together with employees. If tobacco is grafted onto a tomato , then nicotine is practically not found in tobacco leaves, and, conversely, up to 3-4% of nicotine accumulates in tomato leaves grafted onto tobacco.
Tobacco also serves as a raw material in the pharmaceutical industry.
Crop history
Tobacco is native to America. The Indians of South and Central America used tobacco leaves for smoking long before Europeans discovered the continent.
Cultivation areas and yield
Tobacco is currently grown in many countries around the world. The sown area of tobacco is more than 4 million hectares. More than half of the world’s production is in China, the United States, India and Brazil.
In the USSR, over 170 thousand hectares were occupied under tobacco crops. The main regions of cultivation are Moldova, the south and south-west of Ukraine, the countries of Central Asia and the Caucasus, in Russia – the North Caucasus. The average yield of tobacco is 1.5-2.0 t/ha. The maximum yields that could be obtained were 3.0-3.5 t/ha. For example, in the collective farm named after Krupskaya, Urgut district, Samarkand region of Uzbekistan, on an area of 1027 hectares, the yield reached 3.6 t per hectare with an output of 87% of the highest grades.
Botanical description
Tobacco (Nicotiana tabacum L.), or cultivated tobacco, is an annual plant belonging to the Solanaceae family. The genus includes about 70 species.
The root is taproot, penetrates the soil to a depth of 1.5-2 m. The stem is erect, pubescent. Plants reach 100-180 cm in height.
The leaves are large, petiolate or sessile, entire, oval, ovate or elliptical, pointed, with a smooth or wrinkled surface. The number of leaves on one plant reaches 25-50 pieces. Their number and size depend on the variety type and growing conditions. The leaves and stem are covered with short sticky hairs.
Inflorescence paniculate, corymbose. Flowers bisexual, pedicel, pentate, with bracts. The calyx is bell-shaped. The corolla is longer than the calyx, covered with hairs on the outside. The corolla tube is white, the limb is pink or red. The ovary is superior, often bilocular. The stigma is bilobed. Stamens five.
Tobacco is a self-pollinator, but cross-pollination is possible.
The fruit is a two-celled, multi-seeded, oval capsule, 1.5-2.0 cm long, brown, cracking when ripe. In one box, up to 5000 thousand seeds can be formed.
Seeds are oval, dark brown, very small. Weight of 1000 seeds (0.05) 0.06-0.08 (0.12) g.
In tobacco growing, two groups of tobacco are distinguished – cigarette and cigar. Cigarette tobacco is divided into Oriental and American. In the USSR, oriental cigarette tobacco was most widely used, the varieties of which, according to smoking qualities, are divided into aromatic (flavoring, added to tobacco raw materials in small quantities) and skeletal, which form the basis of smoking products.
Biological features
Temperature requirements
Tobacco seeds begin to germinate at a temperature of 10-12 °C. The optimum temperature is 25-30 °C. At temperatures above 35 °C, tobacco growth stops.
Frosts -2 … -3 °С are detrimental to young plants. However, in autumn, tobacco tolerates short-term low temperatures well.
Moisture requirements
The optimum soil moisture for tobacco is 65-70% from the lowest soil moisture capacity.
The greatest need for water falls on planting and rooting seedlings, as well as during the formation of leaves and intensive plant growth. The lack of moisture at this time leads to a decrease in leaf size and premature ripening, which causes a decrease in yield and quality of tobacco.
Excess moisture, especially on heavy clay soils, leads to wetting of plants.
Transpiration coefficient 500-600.
Soil requirements
Light textured soils with a low humus content are considered optimal for tobacco. An excess of organic matter in the soil leads to a deterioration in the smoking qualities of tobacco.
Tabakh is a chlorophobic culture. Sodium and calcium chloride compounds in the soil reduce its combustibility.
Heavy clay, saline and waterlogged soils are unsuitable for cultivation.
Light requirements
Tobacco belongs to light-loving plants.
The lack of illumination leads to a delay in the development of plants and a decrease in the quality of raw materials.
Vegetation
There are two periods in tobacco culture:
- growing seedlings from seeds in greenhouses or soil ridges;
- growing tobacco from seedlings in the field.
The seedling formation period usually lasts 45-50 days, but depends on the variety and usually ends by the time 5-6 true leaves appear.
The period from planting seedlings in the field to the onset of technical ripeness of the leaves of the upper tier lasts 80-120 days. Rooting of seedlings after its transplantation in the field is 10-15 days, after which the phases of stemming, budding, flowering, seed formation and maturation begin.
The formation of leaves in tobacco occurs in tiers.
Technological properties of leaves are determined by varietal characteristics, layering, growing conditions.
Crop rotation
The best forerunners of tobacco in a crop rotation are considered to be winter crops, sugar beets, corn, annual legumes and grasses. On less fertile soils, tobacco is recommended to be placed after leguminous crops and along the reservoir turnover.
With a high saturation of the crop rotation with tobacco, it is allowed to re-plant it in a year, after which it is returned to this field only after 3-4 years. However, the scientifically substantiated inclusion of tobacco in the crop rotation allows increasing its yield by 1.5-2 times compared to permanent and repeated crops.
According to the All-Russian Research Institute of Tobacco and Shag, tobacco is recommended to be placed on light sandy, coarsely skeletal and low-humus podzolized piedmont soils along a layer of perennial grasses; on rich fertile soils – according to the turnover of the layer, in some cases in the third year after perennial grasses.
Tobacco crop rotation
Plantings of tobacco are usually placed near water sources and drying facilities. For this reason, this crop is cultivated in special tobacco crop rotations with a narrow set of crops.
Tobacco crop rotations are tilled, grass-rowed, fruit-shifting. They are built on the placement of tobacco according to the best predecessors for it – winter wheat, perennial grasses, sugar beets, corn, annual legumes and cereal grasses.
Undesirable predecessors are hemp, sunflower, gourds, nightshade crops, as they have pests and diseases in common with tobacco.
In the foothill regions of the Krasnodar Territory, the following tobacco crop rotation is used: 1-2 – alfalfa of the 1st-2nd year of use, 3 – tobacco, 4 – corn, 5 – tobacco, 6 – annual grasses, 7 – tobacco, 8 – spring barley with oversowing perennial herbs. The share of tobacco is 37.5% of the total area.
On poor podzolized soils of the Krasnodar Territory, tobacco is cultivated according to the layer of perennial grasses, as well as in the third year after them in crop rotation: 1-2 – perennial grasses of the 1-2nd year of use, 3 – tobacco, 4 – corn or Sudanese grass, 5 – tobacco, 6 – spring barley with overseeding of perennial grasses. The share of tobacco is 33% of the area.
In a number of farms in the Krasnodar Territory, crop rotation is used: 1-2 – perennial grasses of the 1st-2nd year of use, 3 – winter wheat, 4 – tobacco, 5 – winter wheat, 6 – tobacco, 7 – Sudanese grass, 8 – tobacco.
In the foothill regions of the Kuban, the following 8-field grain-grass row (fruit shift) crop rotation is used: 1-2 – perennial grasses, 3 – winter wheat, 4-5 – tobacco, 6 – winter wheat + intermediate crop, 7 – tobacco, 8 – corn.
In the humid zone of the subtropics of the Krasnodar Territory, the following tobacco crop rotation was introduced: 1 – two-cut clover, 2 – tobacco + intermediate crop, 3 – corn + intermediate crop, 4 – tobacco, 5 – cereals with clover oversowing.
Fertilizer system
Tobacco places high demands on nutrient availability. On average, for the formation of 100 kg of leaves, it absorbs from the soil 6 kg of nitrogen, 1.7 kg of phosphorus, 4.6 kg of potassium and 6.7 kg of calcium. Therefore, this crop responds well to the application of organic and mineral fertilizers.
In turn, nitrogen fertilizers should be used in moderation, since excess nitrogen in the soil degrades the quality of tobacco raw materials. The combined application of nitrogen and phosphorus-potassium fertilizers weakens the negative effect of excess nitrogen.
Since tobacco is a chlorophobic crop, it is not recommended to use chlorine-containing fertilizers.
To obtain 15-20 kg/ha of tobacco leaf yield, it is recommended to apply 10-15 t/ha of manure, 30-60 kg/ha of nitrogen, 80-120 kg/ha of phosphorus, 70-100 kg/ha of potassium (Vavilov; according to others data, from N15-20P50-60K70-75 to N45-60P90-100K120-150, Kolomeichenko). Manure and 2/3 of the entire norm of phosphorus and potash fertilizers are applied in the fall for deep plowing, nitrogen and the rest of the phosphorus and potash fertilizers are applied in the spring during cultivation and for top dressing. When cultivating tobacco under irrigation or excessive moisture, mineral fertilizers are applied in the spring under plowing.
Top dressing is carried out at the beginning of intensive growth of tobacco, that is, 10-12 days after planting seedlings. With weak growth, a second top dressing is carried out 8-10 days after the first.
The lack of boron in the soil can cause the tops of tobacco plants to dry out.
Tobacco responds positively to zinc and lithium fertilizers. For foliar top dressing, a solution containing up to 0.1% lithium is used.
Tillage system
Autumn tillage provides for:
- double stubble peeling to a depth of 5-7 cm and 10-13 cm;
- autumn tillage to a depth of 25-30 cm (Vavilov; according to other sources, 20-22 cm, Kolomeychenko), which should be carried out in a timely manner.
Spring tillage includes:
- fallow harrowing;
- 2-3 cultivations with simultaneous harrowing.
The number of cultivations depends on the weediness of the fields and the timing of planting seedlings.
Growing seedlings
Tobacco is grown only in seedlings. Seedlings are grown in heated and solar greenhouses (nurseries), in film greenhouses or on soil ridges.
Nurseries should be placed on level ground with a slight slope to the south or southwest. They should be well lit and located away from tobacco fields, dryers and tobacco storage facilities in order to prevent infection of seedlings with grouse, mosaic and other diseases.
Nurseries for tobacco are prepared in the same way as for vegetable crops.
Sowing
The timing of sowing tobacco seeds in nurseries is determined by the timing of planting seedlings in the field. Depending on the type of nursery and weather conditions, it takes 35-65 days to get ready seedlings. For example, in the North Caucasus, seedlings in heated greenhouses are obtained on the 45th day, in sunny – on the 55th, in soil beds – on the 60th day after sowing.
The seeding rate for greenhouses is 0.6 g/m2, warm ridges – 0.8 g/m2, cold ridges – 1 g/m2.
Seedling care
Tobacco seedling care includes:
- irrigation;
- ventilation;
- top dressing;
- weeding;
- pest and disease control.
Watering the seedlings is done in small portions of water, but often, preventing the surface of the nutrient mixture from drying out.
The optimum temperature from sowing to germination is 22-28 °C, after germination – 18-25 °C. In greenhouses with technical heating, the temperature is regulated by heating, in greenhouses of another type – by ventilation and covering them with insulation mats.
3-4 times the seedlings are fertilized with mineral and organic fertilizers. The rate of application of mineral fertilizers in top dressing in the form of a solution: nitrogen 2 g/m2, phosphorus 2 g/m2, potassium 5 g/m2. The consumption of the solution is 200 l per 100 m2.
For fertilizing with organic fertilizers, fermented infusion of chicken manure, diluted 1:20 or 1:30, is usually used.
Weed control on seedling crops is carried out as they appear.
Thickened seedlings are thinned out.
Before weeding and thinning, if the nurseries are dry, watering is carried out.
By the time of planting, the seedlings should have a well-developed root system, a flexible, dense stem with 5-6 true leaves.
Seedlings are hardened before sampling. To do this, for 8-10 days it is watered after 1-2 days, stopping it 2-3 days before transplantation.
The output of seedlings is 2500 pcs/m2 on greenhouses with a warming layer, 2000 pcs/m 2 on solar greenhouses, 1500 pcs/m2 on soil ridges. There are 40-60 m 2 of nurseries per hectare of plantings, depending on the variety.
NPO “Tabak” and the Moldavian Research Institute of Tobacco developed a technology for growing seedlings on a nutrient mixture that has not been replaced for 4-5 years. The technology provides for the annual disinfection of greenhouse or greenhouse soil.
Transplanting
Planting seedlings in the field is started when the temperature of the topsoil reaches 10-12 °C and the danger of frost has passed. For most tobacco-growing areas, these conditions fall on the third decade of April. Planting seedlings should be completed before the third decade of May.
Early planting dates are advantageous, especially in the Crimea, where spring is often dry.
The density of standing tobacco plants depends on the area of cultivation and varietal characteristics:
- small-leaved varieties are planted according to the scheme 50 × 12 cm at a plant density of 150-200 thousand pieces/ha;
- medium-leaved – 60 × 20-24 cm with a density of 80-90 thousand pieces/ha;
- large-leaved – 70 × 30 and 90 × 20 cm with a density of 45-55 thousand pieces/ha.
Tobacco planting is carried out by transplanters. For row planting, the МПР-4 transplanter can be used.
Landing care
An important technique for caring for tobacco plantings is considered to be inter-row tillage, which is usually 3-4 with an interval of 8-12 days.
The first treatment is carried out to a depth of 6-8 cm, the subsequent – 10-12 cm. If the soil moisture is insufficient, the treatment is done to a depth of 6-8 cm.
When growing tobacco under irrigation conditions, plantations are watered 2-6 times. Irrigation rate 500-800 m3/ha.
Special methods of planting care are cleaning, topping and pinching tobacco.
Erasure – removal of the lower seedling leaves, followed by their destruction. This technique contributes to a better development of the leaves of the following tiers.
Topping – removal of inflorescences. It is carried out from the beginning of flowering 3-4 times.
Pasynkovanie – removal of side shoots. Carried out simultaneously with topping.
Topping and stepping help to increase the yield, due to the fact that plastic substances are not spent on the further development of inflorescences and side shoots, but are used by the leaves.
Tobacco is considered a medium competitive crop. Parasitic weeds (broomrape (Orobanche) and dodder (Cuscuta)) can appear in tobacco plantations. In the fight against parasitic weeds, crop rotation is of great importance, which should include crops resistant to these weeds: barley, wheat, rice, oats, millet or perennial cereal grasses.
The main pests of tobacco include: slugs, bear, tobacco thrips, wireworm, meadow moth, black weevil. Main diseases: black root rot, bacterial grouse, powdery mildew, mosaic, ring spot, etc.
Harvest
Tobacco leaves ripen unevenly. The oldest lower leaves ripen first, then the middle and last the upper leaves. Most varieties have five tiers of ripening.
Tobacco leaves are harvested by hand. For this, 5-10 breaks are made within 1.5-2 months. The number of breaks, as a rule, coincides with the number of maturation tiers. For one break, 3-7 leaves are removed from one plant.
The harvested leaves are stacked in packs and immediately sent to drying sheds, where they are sorted, strung on cords 5-6 m long and dried.
Drying tobacco
Tobacco drying is carried out in two phases: languor and fixation (drying itself).
Languishing is carried out in drying sheds on special frames – wagons on which cords with strung leaves are hung. The optimal languishing temperature is 25-30 °C, while breathing and evaporation of moisture by plants continues. When languishing in the tissues of the leaf, the breakdown of proteins occurs, the conversion of starch into sugar and the destruction of chlorophyll. The content of nicotine in the leaves decreases, but the amount of aromatic substances increases. Moisture loss during languishing is 6-7%, dry matter – 10-16%. As a result of languishing, the leaves turn yellow, their quality increases. The duration of languor is usually 3-4 days.
After languishing, fixation is carried out, that is, the final drying of tobacco in the sun for 15-20 days or in special fire dryers at a temperature of 40-42 °C at the beginning of drying and 48-50 °C at the end.
For tobacco drying, СТГ-1.5 production lines can be used, which can reduce labor costs by 35-40% compared to pipe-fired drying. The production line СТГ-1.5 for drying tobacco, fixed on cords in vertical garlands, allows the use of a continuous technology of languishing, drying and moistening the leaves.
A relatively newer way of drying large-leaf tobacco – in bulk – is to place the leaves in cassettes equipped with metal needles. For this method, the СТМ-60, УСТП-10, 801-ТУ installations are used.
After drying, the leaves are sorted according to the established standard into five grades, tied into bales and handed over to procurement points. Humidity of commercial raw materials in bales (20-25 kg each) should not exceed 19%. From the procurement points, tobacco is sent to fermentation plants to improve quality and impart resistance to mold, from where it is already delivered to tobacco factories.
Sources
Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher educational institutions).
V.V. Kolomeichenko. Crop production / Textbook. — M.: Agrobusinesscenter, 2007. — 600 p. ISBN 978-5-902792-11-6.