Tobacco is an important cash crop which is grown for its leaves.

It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines.

It is most commonly used as a drug.

It is smoked as pipe, cigar, cigarette or hookah, used as snuff or chewed as a quid in many forms.

Tobacco belongs to Solanaceae family (nightshade family). It is herbaceous annual plant.

Tobacco is a tropical plant but can be grown in wide range of climates.

Introduction

The most tobacco growing countries are china, India, Brazil, Pakistan, Argentina, Bangladesh, Japan, and Germany.

In Nepal it is grown in eastern terai region namely Bara, Parsa, Rautahat, Sarlahi, Dhanusha, Mahottari, Saptari, Siraha districts.

Cultivated species are classified into 2 species. Nicotina tabcum Nicotina rustica

The NARC released variety of tobacco is Belachapi-1 and recommended region for this variety is terai.

Introduction contd…

Plant management is a system of managing all the conditions and criterions required for over all development and higher yield of crop/ plant.

It consists of soil structure maintenance for optimum air entry

(soil aeration), regulation of plant stand, optimum plant population, water management, nutrition regimes, weed control and pest control.

It is a series of practices for bringing up higher yield of any plant.

Tobacco needs suitable plant management practices that uplift the production. The plant management practices of tobacco includes soil loosening, water management, weed management, topping, de- suckering.

Plant management

Tobacco is quick growing crop, becomes ready to harvest in 90-120 days after transplanting. So it requires good aeration for growing roots.

The size of root mainly determines the yield of crop.

The smaller the size of root the less water it uptakes resulting comparatively low biomass. For this reason soil loosening are preferred immediately after seedling are rooted which is about a week after transplanting and are stopped before the tobacco plants cover the space between rows.

Seedlings are susceptible to poor aeration and water logging condition so there may be 3-8 soil loosening followed by weeding.

Loosening helps in better root growth, better canopy is established and increases the infiltration rate because loosening disturbs the crustation.

Soil loosening

It consists of removal of the terminal bud with or without some of the small top leaves just before or after the emergence of the flower head.

15-20 cm from upper most leaf removed.

This practice stimulates the development of the remaining leaves.

It gives a uniform quality product and prevents excessive coarseness in tobacco.

It prevents the plants from producing seeds and allows carbohydrates and other nutrients to go towards vegetative part instead of reproductive.

This practice cause thickening of leaves and increase their body.

It also helps in increasing nicotine content in upper leaves.

Topping causes uniform ripening of leaves and high quality leaves.

Topping

Stage of topping according to type of tobacco

Topping contd….

Type of tobacco Stage of topping

Flue-cured At flower head

Burley 12-24 leaves level

Cheroot 14-16 leaves level

Cigar filler 12-14 leaves level

Hookah and chewing 8 leaves level

Natu At flower head

When the plants are topped, apical dominance is broken and lateral buds, called sucker develop. The practice of removing these suckers is called de-suckering.

This practice can be done by manually, using chemicals such as maleic hydrazide.

Manual method is time consuming and cumbersome.

Removal of suckers should be done before they become large enough to restrict the development of leaves.

De-suckering is conducted 5-6 times at an interval of a week.

The main aim of topping and de-suckering operations is to divert the energy and nutrients of the plant from floral head to leaves which influence the yield and quality of tobacco.

De suckering

Irrigation is the artificial application of water to the field for the purpose of overcoming critical stages in plant and ultimately to increase the plant yield.

The irrigation requirement depends upon the type of tobacco, soil texture and environment.

The daily water demand varies from 0.15-0.625 cm depending upon crop stages and agro-ecological conditions.

Irrigation scheduling can be made depending upon the moisture depletion from soil, critical stages of plant and soil texture.

The critical stages in tobacco are knee high to bloom stage. During this period sufficient level of soil moisture should be maintained for achieving higher productivity.

In light soils 6-7 irrigations are required for flue cured tobacco.

Irrigation or water management

First irrigation is given at three weeks after planting.

Tobacco needs light but frequent irrigations. The maximum requirement of water is after one month of transplanting and low requirement after flower budding.

The optimum soil moisture to be maintained is 70% of field capacity before blossoming and 40% of field capacity after blossoming.

Use of quality water is very important in tobacco. High chloride containing water should be managed properly because it reduced the burning capacity of tobacco.

Excess chlorides in tobacco inhibits the leaf burn, reduce leaf storage capacity,

leads to two faced leaves which ultimately results in low pricing index.

Too much water in the field reduces the fertilizers efficiency, causes the leaching of nutrients from soil.

So drainage is equally important as irrigation.

Water management contd……

Weed control is an important production practice in tobacco since weed competition for moisture and nutrients may result in yield losses.

In addition to reduced yields, weeds may also be a serious source of foreign material in mechanically harvested tobacco.

Good weed control in tobacco is best achieved by utilizing all available methods of weed control in an integrated program.

Weed management

1.Sanitation

Many of the problem weeds in tobacco are the result of seed produced in the field during the preceding crops or seed blown into the field or onto plant beds.

Preventing weeds from producing seed in these areas may aid in reducing weed problems in succeeding tobacco crops.

Destroying weeds around the plant bed area as well as utilizing natural or artificial windbreaks will reduce weed problems.

Fumigation is done to prevent contamination of weeds in the bed.

Methods of controlling weeds

Orobanche which is a root parasite and is a menace to the tobacco crop is kept down by hand pulling.

This weed derives all nourishment from tobacco plant.

The only way to control this weed is to collect and destroy before seed formation.

2.Physical control

Crop rotation is important in handling weed problems in tobacco, and in disease and nematode management systems.

Large-seeded broadleaf weeds, including Cocklebur, Morningglory, Jimsonweed, and Sicklepod; and small-seeded broadleaf weeds such as ragweed and hairy galinsoga are not controlled by most tobacco herbicides.

Perennials are difficult to control in tobacco.

Rotations that include corn, cotton, sorghum or soyabeans will help to reduce weed pressure in tobacco field.

3.Crop Rotation

Crop competition can be an effective tool in tobacco weed management.

Tobacco is a rapidly growing crop and the large leaves shade weeds.

Use good cultural practices to promote rapid tobacco growth, and use as narrow rows as recommended to help shade weeds thus reducing weed infestation in the tobacco field.

5.Chemical method/ herbicide application

Soil application of ethylene di bromides @ 2.5ml per m2 is practiced to control severe parasitic weeds like Orobanche ramose and Orobanche minor.

Similarly herbicides like alchlor, diuron, simazine, atrazine, pendimethalin etc can be used as pre-plant or pre-emergence.

4.Crop competition

Harvest is the process of gathering the economic part of the plant.

The stage of maturity and the methods of harvesting differ with the type of tobacco.

The tobacco leaves do not ripe uniformly. Ripening starts from lower to upper leaves.

The ripening process of tobacco consists of deposition of starch and elimination of green matter. Change in color of leaf from green to slightly yellow color is the time for harvesting.

It starts 90-120 days of transplanting.

The number of days from transplanting to harvest will vary considerably by variety and growing season.

Harvesting

There are two methods of harvesting tobacco.

1. Priming The method of harvesting properly matured leaves leaving some leaves which are not

fully ripened for better quality is called priming.

Priming requires several picking and harvest period for prime leaves may last for 3-6 weeks.

Picking starts from lower most leaves which mature first and continue until the uppermost leaves are ripened.

Each time 2-3 leaves are harvested at weekly interval. The entire harvest is completed in about 5-6 priming.

Priming begins after 14-21 days of topping.

After harvesting the leaves are strung on bamboo stick of about 1.5 m length at the rate of 60-80 leaves per stick and taken to barn for curing.

Methods of harvesting

Hookah, bidi, cigar, cheroot and chewing tobaccos are harvested by cutting the entire plant close to the ground with sickle when middle leaves show the first tinge of yellow.

The time of cutting stalk depends upon the type of tobaccos.

Harvest bidi tobacco when majority of top leaves develop red rusty spots known as spangles.

cigar and cheroot tobacco are harvested when the leaves turn yellowish green and become brittle which breaks on folding.

Harvesting of chewing tobacco is done when the leaves develop pronounced puckering and hookah tobaccos are harvested when there is indication of yellowish brown spots of puckering on leaves.

The stalk is then hung upon a lath or stick. A lath or stick holds 6-8 stalks. Leaves are not removed from the stalk until curing is completed

2. Stalk cut method