• One of the best way of improving any crop is by the use of pure seed.
• It is also the cheapest way, particularly in a commercial crop like tobacco where the cost of production is quite high and the cost of seed required is comparatively negligible.
• Yet on this vital and cheapest input depends the returns the farmer obtains from other costly inputs from his land and labour.
• The cultivation of FCV tobacco was introduced into the Guntur area of Andhra Pradesh, seed used to be imported every year from U.S.A. on the mistaken belief that locally produced seed was of inferior quality.
• Seed produced indigenously is as good as imported one in maintaining the yield and quality of the crop and that the deterioration noticed in some cases was not owing to the indigenously produced seed but due to contamination.
• Subsequently, seed of FCV tobacco varieties used to be produced in the country itself and distributed to the growers first by M/s. I.L.T.D. Co. Ltd and subsequently by the State Agricultural Department also.
• The smallness of the seed and the large quantity of seed produced by a single plant pose special problems in maintaining the purity of a variety and one has to be extremely vigilant at all stages of seed production to prevent contamination.
• At the same they do have an advantage in that the rate of coverage is very high in tobacco. On an average, about 100 kg of seed is obtained per hectare from the crop raised for leaf purposes.
• This is sufficient to sow about 20 ha of nursery which in turn gives enough seedlings to plant about 2,000 ha of crop.
• Thus the seed obtained from one hectare is sufficient to cover about 2,000 ha. This is a great asset in seed production and very few cultivated crops have such a high rate of coverage.
• In tobacco, quality is more important than quantity and particularly so in an exportable type like FCV tobacco which has to withstand international competition.
• This high rate of seed coverage was taken advantage of in maintaining the quality and yield by distributing the foundation seed to growers unlike in other crops where only certified seed "produced through A, B and C class registered growers is supplied.
• Tobacco is a self-pollinated crop. The cross-pollination has been estimated to range from 4 to 20 per cent.
• It varies from variety to variety, location to location, season to season and depends to a good extent on pollinating agents like humming birds, hawk moths, bees, etc. Protection from cross pollination is necessary in pure seed production.

• For want of space in the farm, the foundation seed is multiplied in selected cultivators' field.
• In the past when all the seed plots were located in one village or in a few neighbouring villages, there was a total failure of crop in some years due to seasonal vagaries or incidence of pests and diseases in that area.
• To ensure against such failure the seed plots are now dispersed in different districts.
• As far as possible each variety is multiplied in a separate village. In the village all the seed plots are planted in one or more compact blocks of convenient size.
• Around each block about 10 guard rows are left out to prevent contamination due to chance cross pollination, even though it is reported to be very much less.
• Strict supervision is exercised at the time of planting and subsequent gap filling to prevent mechanical mixture of seedlings of different varieties.
• Subsequently three rounds of rouging, i.e. removal of foreign types found in a pure line, is done in all the seed plots.
• During these rounds, each plant is examined closely and any off-types, doubtful plants and diseased plants are eliminated.
• If the off-types are unwanted, i.e. a FCV tobacco plant in a Lanka tobacco seed plot or vice versa, they are pulled out and destroyed.
• The FCV tobacco off-types in FCV tobacco seed plot, the doubtful plants and the diseased plants are topped in the first round of rouging and suckered in the subsequent rounds of rouging.
• Plants, which differ slightly from the pure line in one or two minor characters, are listed as doubtful plants (biotypes).
• Normally the first round of rouging is done when the crop is about to flower, the second round when the crop is in peak flowering and the third round before the last priming of the leaves, i.e. a few days before the harvest of the capsules.
• The identification characters are normally growth habit, plant height, size and shape of the leaves and their angle of attachment to the stem, colour of the midrib and stem, size and shape of inflorescence, disposition of the flowers on the panicle, time of flowering, size, shape and colour of different floral organs etc.
• As the morphological characters are likely to be influenced by environment and cultural practices, one has to be very careful in identification of types and it needs an intimate acquaintance of the crop.
• A thorough knowledge of the characteristics of the variety, a trained eye and a good judgement are essential to detect the rouges, off-types and doubtful plants in a large crop at early stages of plant growth.
• Some of the diseases like mosaic and leaf-curl distort the plants and make its identification difficult. Further, there is a possibility of carrying mosaic diseases through the chaff of the seed capsules into the seed bed and it is a highly contagious disease.
• Hence, all such diseased plants are topped. During these rounds of rouging detailed records are kept regarding the number and nature of off types and doubtful and diseased plants encountered in each block of the seed plot.
• The occurrence of spontaneous mutations is very low in tobacco probably because of its polyploid constitution. Hence, the possibility of contamination on this account is negligible.

• When the capsules are dry, they are harvested and dried at a central place.
• As the tobacco seed is very small there is great scope for admixtures and to prevent this, each variety is handled at a separate place and this place is kept constant for that variety year after year.
• After a few days drying, the capsules are threshed and sieved through sieves of 10 and 20 mesh (i.e. 100 and 400 holes/sq inch respectively) which remove all the coarse foreign matter particles like, chaff of capsules, etc. and stored in drums till all the threshings are completed.
• When the threshings are over, the seed from each lot is dried in the sun for two or three days to bringdown the moisture in the seed to the desired level of less than 5 per cent.
• Experiments have shown that higher moisture content brings down the viability of the seed during storage.
• The seed is then cleaned either in a cleaning machine or by sieving with a 30 mesh sieve before a running fan.
• The sieve catches the small chaff particles and due to wind velocity all the immature and shrivelled seed along with fine particles of chaff are separated.
• Finally the seed is sieved with a 40 mesh sieve, all the seed is retained in the sieve and the fine dust comes down.
• Then the seed is packed into ½ kg packets in polythene bags, sealed at both ends and distributed.
• Recently polythene bottles of ½ kg capacity are being used instead of packets.
• On each packet or bottle are printed the name of the institute, the name of the variety and its code number.
• In case of complaints, if the name of the variety and code number are furnished, it will be possible to trace from records the entire history of the lot like its location, date of planting, dates of gap filling, dates of rouging, number and nature of off-types met with, date of harvesting of capsules, threshing, cleaning and packing of seed together with its purity, moisture content and viability along with the details of the personnel who supervised these operations.
• As no seed-borne diseases like wild-fire, black-fire etc. have so far been reported in India, the seed is not being treated at present with disinfectants like silver nitrate solution.

• The first step consists of raising a nucleus seed plot. It has an area of about 0.25 ha with a population of about 4,000 plants.
• In this plot the most typical plants, strictly confirming to the description of the variety in all respects are selected and selfed.
• Normally 100-200 plants are selfed depending on the quantity of nucleus (selfed) seed required.
• At the time of selfing all precautions like removing the capsules and opened flowers, if any, and dusting the panicle with a suitable insecticide to ward off caterpillars and capsule borers are taken.
• For selfing, white sulphide paper bags of 43 cm x 20 cm x 9 cm size with side folds are used.
• If the bags are not made of water proof, the gummed portions are waxed to prevent the gum giving way and the bags opening up on wetting due to dew and rain.
• To get the maximum quantity of seed the selected plants are normally selfed as soon as a few flowers on the panicles open.
• If selfing is done at a very early stage, i.e., as soon as the panicle emerges and even before any flowers open, then the peduncle will be too soft and it generally breaks during wind due to the weight of the bag.
• After selfing, the bags are to be lifted periodically as the panicle grows. Otherwise the growing panicle pierces the bag and comes out.
• In the selfed plants all the suckers in top leaf axils are periodically removed to prevent contamination.
• When the capsules are dry, all the selfed panicles from the nucleus seed plot are harvested, dried and threshed. The seed is cleaned and labelled as nucleus (selfed) seed of that particular variety of tobacco.
• The nucleus seed from all the selfed plants is bulked for maintaining the residual genetic variability in the crop population in order to retain its vigour as well as plasticity so that it can adopt itself to varying environmental conditions.
• It is now fairly well proved that a variety is at its best when maintained at the level of hybrids resulting from the amount of natural cross pollination prevailing in the crop.
• The purity to be aimed in crop production should be such as would result in produce of a commercially acceptable purity and uniformity.

• In the succeeding season this nucleus seed is sown in the nucleus nursery. Experimental results have shown that the tobacco seed that falls deep during sowing does not germinate and lies dormant.
• In the next season when such seed comes to top during preparatory cultivation it readily germinates.
• If the same variety is sown in the same nursery area year after year there is no harm.
• Otherwise there will be contamination, which is estimated to be about 50 seedlings per square metre of nursery bed area which is quite high.
• To avoid this nursery contamination, the same variety is to be sown in the same nursery area year after year. If the variety is to be changed, then the nursery area is first sterilised by rabbing, i.e., burning the area with paddy husk, brush wood or any other slow burning trash material.
• The seedlings from this nucleus seed plot, selfed seed is collected as described above.
• All the seed produced by the Institute is collected from the crop raised mainly for leaf purposes in black soils, as topping is still not widely practised in these soils.

• Random and representative samples of seeds are taken from all the lots in each variety for a check about its physical purity, varietal purity, moisture content and germination percentage. Seed from only such of the lots, which conform to the following minimum standards alone, is released for distribution.

At least 0.5 g sample from each lot is examined for this purpose.

• Pure seed 97-98%
• Other crop seed - Nil
• Weed Seed – Nil
• Inert matter 2-3%

• The size, shape and colour of the seed of different varieties of tobacco do not differ appreciably to facilitate their identification. Hence, it is necessary to grow the crop for varietal identification for which atleast 200 plants are raised in the field under ideal conditions so that the typical characteristics of the variety express themselves freely and fully.
• True type-Not less than 99%
• FCV off types – Not more than 0.4%
• Non-FCV off types – Not more than 0.02%
• Doubtful plants – Not more than 0.5%

• As the seed is packed for distribution during April-May when the atmospheric temperatures are high, the seed is tested for viability at the optimum temperature of 22° C in a low temperature incubator.
• These tests are conducted in covered glass Petri-dishes of 8-10 cm diameter and ½ cm height.
• Two discs of Whatman No.2 filter paper are kept in the bottom dish and one in the inside top of the upper dish and moistened daily to keep the moisture at the optimum level.
• One hundred squares are drawn with a lead pencil in the upper filter paper disc of the bottom dish and seeds are kept one in each square at about 0.5 cm apart.
• For each lot, 1,000 seeds are kept for viability test in 10 dishes. Germination counts are started on the 7th day and continued upto 14th day.
• If there is difference of 10% and above in the germination of seed between any two dishes in a lot the test is repeated. Only the seed from those lots which give more than 90% germination is released for distribution.
• As soon as the atmospheric temperatures come down, i.e. during July-August, all the seed lots are tested for viability at room temperature for confirmation.

• The moisture content of seeds is one of the most important factor influencing their retention of viability and general appearance. In tobacco the moisture content of the seed should not be more than 5%.

• Nucleus seed plot
• Nucleus nursery
• Foundation seed plots
• Foundation seed development