Method of sowing the seed in nursery:
Usually treated or water-soaked seeds are broadcast on the surface of the beds and mixed in the soil up to a depth of 1.5 to 2.0 cm with the help of a rake. Before sowing, the seeds are mixed with ash or fine sand in 1:15 or 1:20 ratio for their proper or uniform distribution on the beds. Sometimes the seeds are sown in shallow furrows prepared at 5.0 cm distance from each other. Later the seeds are covered with leaf mould and sand mixture and are pressed.
Care of seedlings in nursery:
The following points needs attention in nursery.
- To minimize damage to the seedlings from scorching sun or beating rains, it is necessary to shade the nursery by a thatch prepared out of grass or sugarcane leaves. The thatch should be removed soon after the seeds have emerged and seedlings have 2 leaves.
- In order to keep the beds moist they should be irrigated by watering cane every evening. There should not be water accumulation at any spot of the bed. Later the beds are flooded with controlled flow of water.
- Seedlings must be thinned out 10-15 days after sowing in order to protect them from damping off.
- Resetting of 3-4 week old seedlings at a distance of 5 x 5 cm in new beds may be done for hardening of the seedlings.
- A spray of dithane M 78 @ 11-12 litres of 0.03% solution for every 40 m2 area prevents spread of fungal diseases.
- For control of insect-pests, a spraying of carbaryl 50 WP (Sevin 50 g in 22 liters of water) is useful.
- Transplanting age of seedlings is 7-9 weeks for tabacum and 5-6 weeks for rustica. Transplanting of younger seedlings causes a higher percentage of gaps while aged or woody seedlings result in a poor growth of plants.
- Irrigation of the bed should be stopped about 10-15 days before transplanting so that they may become drought-resistant and may resist the setback. However, in the evening of the preceding day of pulling the seedlings, the beds must be watered copiously to facilitate the pulling of the seedlings without injury to the root system.
Manure and Fertilizers
In tobacco crop, the economic returns are largely dependent on the right combination of yield and quality rather than the yield alone. The quality in tobacco, particularly in the smoking types, depends on the balance of the nutrients in the leaf. Heavy application of N increases the yield, but has an adverse effect on the quality. With greater of N supply, the carbohydrate-nitrogen (C:N) ratio gets reduced. On the other hand, better quality in chewing, bidi and hookah tobaccos is generally associated with higher yields that may be obtained with heavy dose of N together with other nutrients. In flue cured tobaccos for cigarette and cigar better quality leaves are obtained from partially N starved plants. Therefore, nutrient requirements of different tobaccos are different.
Phosphorus requirement of tobacco is comparatively low. Potash is an important element, particularly for smoking tobacco. Potash also improves the physical qualities of the leaf like elasticity and low prominence of veins.
In addition to inorganic fertilizers, application of organic matter in the form of well rotten FYM or compost is also recommended @ 7-8 tonnes/ha for heavy soils and 10-12 tonnes/ha for light soils to improve the physical condition of the soil. It may be applied 1 month in advance and ploughed in the soil. In Gujarat, green manuring with sunnhemp or castor cake was recommended for bidi tobacco grown in light soils. Phosphorus should be supplied through single superphosphate and potash through potassium sulphate. Through these fertilizers, sulphur requirement of tobacco is also fulfilled. Potash should never be supplied through potassium chloride. The leaf quality decreases due to chloride as thickness of leaf increases. Humus containing soils are best for cigar tobacco. Calcium decreases the thickness of leaves, and increases crop yield. Due to magnesium deficiency, a special type of chlorosis is developed in leaves which is known as Sand drown. Due to boron deficiency, lower leaves may become thick.
The field for tobacco transplanting should be well prepared. Seedlings of 15 cm height with 5-7 leaves are good for cigarette tobacco, but bidi tobacco requires smaller seedlings. Transplanting should be done in the late afternoon to avoid the heat of the sun.
Optimum time of planting and spacing vary with the type of tobacco. Transplanting is usually done in October-November in case of winter crop, while at the end of March or in the beginning of April for the second or summer crop. Immediately after transplanting, light irrigation should be given for establishment of seedlings. Seedlings not established well should be replaced with fresh seedlings within a week of transplanting.
FCV and natu in black soils, and FCV in light soils in A.P. are planted at 80 x 80 cm and 100 x 60 cm respectively. In Tamil Nadu, cigar and cheroot tobacco are spaced at 75 x 50 cm, where as chewing tobacco at 75 x 75 cm. In Bihar, chewing tobacco is planted at 90 x 60 cm. Bidi tobacco in Gujarat and Karnataka is planted at 75 x 75 cm and 105 x 45 cm respectively. In West Bengal, tabacum is planted in wider spacing of 90 x 90 cm than rustica (60 x 45 cm). The hookah tobacco (rustica) in U.P. is grown at 45 x 45 cm, while the tabacum at 50 x 45 cm.
Water management of tobacco crop depends upon the type of tobacco and the region where it is raised. In order to raise a successful crop on light soils, it is necessary that watering be done timely through light irrigation. Too much irrigation causes leaching of the nutrients from the soil and produces slick leaf with dirty colour. Insufficient irrigation, on the other hand, restricts crop growth, and the curing of leaf becomes difficult. Tobacco can not tolerate waterlogging at any stage of growth, and also can not withstand drought.
In northern light soils of Andhra Pradesh, altogether 6-7 irrigations are required by flue- cured tobacco, starting 3 weeks after transplanting, at 18 mm each for first 2 irrigations, 25 mm each for next 2 irrigations and 37 mm at topping stage and 25 mm each for the last 2 irrigations.
In case of the flue-cured tobacco, water quality is important. The quality of tobacco leaf gets adversely affected if crop is irrigated with water having a chloride content in excess of 50 ppm. Excess chlorides in tobacco inhibit the leaf burn; reduce leaf storage quality, leads to 2- faced leaf, which ultimately results in low pricing index.
The flue-cured Virginia tobacco grown on black cotton soils is rarely irrigated, whereas the one grown on light soils is given 5-7 irrigations. The cigar, cheroot and chewing tobacco in Tamil Nadu and chewing tobacco in Bihar are normally irrigated and about 15-18 irrigations are applied. The bidi tobacco in Karnetaka, Maharashtra and the hookah and chewing tobaccos of West Bengal are raised as rainfed, but under drought 1 or 2 irrigations are desirable under drought conditions.The hookah and chewing tobacco raised in Uttar Pradesh are irrigated and generally 12-15 irrigations are applied.